Dissertationen: „Anode Li“

1

Cen, Yinjie. „Si/C Nanocomposites for Li-ion Battery Anode“. Digital WPI, 2017. https://digitalcommons.wpi.edu/etd-dissertations/468.

Der volle Inhalt der Quelle

Annotation:

The demand for high performance Lithium-ion batteries (LIBs) is increasing due to widespread use of portable devices and electric vehicles. Silicon (Si) is one of the most attractive candidate anode materials for the next generation LIBs because of its high theoretical capacity (3,578 mAh/g) and low operation potential (~0.4 V vs Li+/Li). However, the high volume change (>300%) during Lithium ion insertion/extraction leads to poor cycle life. The goal of this work is to improve the electrochemical performance of Si/C composite anode in LIBs. Two strategies have been employed: to explore spatial arrangement in micro-sized Si and to use Si/graphene nanocomposites. A unique branched microsized Si with carbon coating was made and demonstrated promising electrochemical performance with a high active material loading ratio of 2 mg/cm2, large initial discharge capacity of 3,153 mAh/g and good capacity retention of 1,133 mAh/g at the 100th cycle at 1/4C current rate. Exploring the spatial structure of microsized Si with its advantages of low cost, easy dispersion, and immediate compatibility with the prevailing electrode manufacturing technology, may indicate a practical approach for high energy density, large-scale Si anode manufacturing. For Si/Graphene nanocomposites, the impact of particle size, surface treatment and graphene quality were investigated. It was found that the electrochemical performance of Si/Graphene anode was improved by surface treatment and use of graphene with large surface area and high defect density. The 100 nm Si/Graphene nanocomposites presented the initial capacity of 2,737 mAh/g and good cycling performance with a capacity of 1,563 mAh/g after 100 cycles at 1/2C current rate. The findings provided helpful insights for design of different types of graphene nanocomposite anodes.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

2

Gullbrekken, Øystein. „Thermal characterisation of anode materials for Li-ion batteries“. Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19224.

Der volle Inhalt der Quelle

Annotation:

Coin cells with lithium and graphite electrodes were assembled using different combinations of graphite material and electrolyte. Specifically, three commercially available graphite materials and five electrolyte compositions were studied. The cells were discharge-charge cycled with varying parameters in order to determine the performance of the graphite materials and electrolytes. Particularly, a temperature chamber was employed to cycle some cells at temperatures between 0 and 40°C to find the significance of the electrolyte composition and graphite material on the cell performance at these temperatures. The cycled cells were disassembled and samples from the graphite electrode soaked with electrolyte were prepared for thermal analysis, specifically differential scanning calorimetry (DSC). The thermal stability of the graphite electrodes and the influence from the graphite and electrolyte properties and the cycling parameters were analysed. In order to facilitate the interpretation of the results from discharge-charge cycling at different temperatures, DSC analysis from -80 to +50°C was performed on the pure electrolytes.Confirming previous studies, it was found that both the thermal stability and cycling performance were highly influenced by the properties of a solid electrolyte interphase (SEI), situated between the graphite surface and the electrolyte and formed during cycling. The three graphites were good substrates for stable SEI formation, exhibited by high thermal stability after being cycled at room temperature. After cycling with a temperature program, subjecting the cells to temperatures between 0 and 40°C, the thermal stability was generally reduced. This was attributed to increased SEI formation. The properties of both the electrolyte and graphite influenced the SEI and consequent thermal stability, though in different ways.The cell capacity was considerably reduced upon cycling at lower temperatures, such as 10 and 0°C. The results indicate that the electrolyte properties, particularly the viscosity and resulting conductivity, played the most important role in determining the cell performance. Low viscosity electrolyte components should be utilised, maintaining the electrolyte conductivity even at reduced temperatures. The graphite properties did not influence the cell performance at the temperatures studied. Advice is given on which electrolyte components should be avoided to build Li-ion cells performing acceptably at temperatures from 0 to 40°C.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

3

FUGATTINI, Silvio. „Binder-free porous germanium anode for Li-ion batteries“. Doctoral thesis, Università degli studi di Ferrara, 2019. http://hdl.handle.net/11392/2488081.

Der volle Inhalt der Quelle

Annotation:

To develop high energy density lithium ion batteries, the use of new electrode materials is required. Germanium is among the possible alternatives to the most commonly used anode, graphite (372 mAh/g), thanks to its four-times higher theoretical gravimetric capacity (1600 mAh/g). Here is presented a two-step method to produce a binder-free porous germanium anode, depositing the semiconductor on metallic substrates by means of Plasma Enhanced Chemical Vapour Deposition (PECVD) and subsequently performing an electrochemical etching with hydrofluoric acid to create a porous structure. The Ge-based electrode attained a capacity of 1250 mAh/g at a current rate of 1C (1C=1600 mA/g) and retained a stable capacity above 1100 mAh/g for more than 1000 cycles tested at different C-rates up to 5C. Both deposition and etching techniques are scalable for industrial production, whose fields of application could be aerospace or medical applications, due to the high cost of germanium as a raw material.
Per sviluppare batterie agli ioni di litio ad alta densità energetica, è necessario l’utilizzo di nuovi materiali elettrodici. Il germanio è una delle possibili alternative all’anodo più comunemente impiegato, la grafite (372 mAh/g), grazie alla sua capacità gravimetrica teorica quattro volte maggiore (1600 mAh/g). In questo lavoro viene presentato un processo in due fasi per realizzare un anodo in germanio poroso privo di legante (binder), realizzando film di semiconduttore su substrati metallici mediante deposizione chimica da fase vapore assisitita da plasma (PECVD) ed effettuando successivamente un attacco elettrochimico con acido fluoridrico per creare una struttura porosa. L’elettrodo in germanio poroso ha raggiunto una capacità di 1250 mAh/g ad una velocità di carica/scarica pari ad 1C (1C = 1600 mA/g) mantenendo, inoltre, una capacità stabilmente superiore a 1100 mAh/g per più di 1000 cicli a diversi C-rate fino a 5C. Sia la tecnica di deposizione che quella di attacco chimico sono scalabili per la produzione industriale, i cui possibili campi di applicazione sono il settore aerospaziale o medico, a causa dell’elevato costo del germanio come materia prima.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

4

Janíček, Zdeněk. „Stabilita katodového materiálu pro LI-ion akumulátory“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220974.

Der volle Inhalt der Quelle

Annotation:

This diploma thesis focuses on study of positive electrode materials for Li-Ion batteries. Our aim are intercalation materials whose are really perspective materials whose are widely used in this case. The theoretical part of my thesis focus on basic study of Li-ion batteries and their parameters. We studied charging and discharging processes. AFM and SEM were used as additional techniques for study LiCoO2 a Li0,975K0,025CoO2. We tested lifetime and stability of electrode as a perspective material for electrode for Li-ion batteries.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

5

Buiel, Edward. „Lithium insertion in hard carbon anode materials for Li-ion batteries“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0013/NQ36573.pdf.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

6

Mayo, Martin. „Ab initio anode materials discovery for Li- and Na-ion batteries“. Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/270545.

Der volle Inhalt der Quelle

Annotation:

This thesis uses first principles techniques, mainly the ab initio random structure searching method (AIRSS), to study anode materials for lithium- and sodium- ion batteries (LIBs and NIBs, respectively). Initial work relates to a theoretical structure prediction study of the lithium and sodium phosphide systems in the context of phosphorus anodes as candidates for LIBs and NIBs. The work reveals new Li-P and Na-P phases, some of which can be used to better interpret previous experimental results. By combining AIRSS searches with a high-throughput screening search from structures in the Inorganic Crystal Structure Database (ICSD), regions in the phase diagram are correlated to different ionic motifs and NMR chemical shielding is predicted from first principles. An electronic structure analysis of the Li-P and Na-P compounds is performed and its implication on the anode performance is discussed. The study is concluded by exploring the addition of aluminium dopants to the Li-P compounds to improve the electronic conductivity of the system. The following work deals with a study of tin anodes for NIBs. The structure prediction study yields a variety of new phases; of particular interest is a new NaSn$_2$ phase predicted by AIRSS. This phase plays a crucial role in understanding the alloying mechanism of high-capacity tin anodes, work which was done in collaboration with experimental colleagues. Our predicted theoretical voltages give excellent agreement with the experimental electrochemical cycling curve. First principles molecular dynamics is used to propose an amorphous Na$_1$Sn$_1$ model which, in addition to the newly derived NaSn$_2$ phase, provides help in revealing the electrochemical processes. In the subsequent work, we study Li-Sn and Li-Sb intermetallics in the context of alloy anodes for LIBs. A rich phase diagram of Li-Sn is present, exhibiting a variety of new phases. The calculated voltages show excellent agreement with previously reported cycling measurements and a consistent structural evolution of Li-Sn phases as Li concentration increases is revealed. The study concluded by calculating NMR parameters on the hexagonal- and cubic-Li$_3$Sb phases which shed light on the interpretation of reported experimental data. We conclude with a structure prediction study of the pseudobinary Li-FeS$_2$ system, where FeS$_2$ is considered as a potential high-capacity electrochemical energy storage system. Our first principles calculations of intermediate structures help to elucidate the mechanism of charge storage observed by our experimental collaborators via $\textit{in operando}$ studies.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

7

Hapuarachchi, Sashini Neushika Sue. „Fabrication and characterization of silicon based electrodes for Li-ion batteries“. Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/207430/1/Sashini_Hapuarachchi_Thesis.pdf.

Der volle Inhalt der Quelle

Annotation:

This thesis presents the synthesis and characterization of silicon electrodes to address critical challenges in development of high capacity Li-ion batteries. Failure mechanisms of silicon electrodes are investigated at different material length scales and effective strategies are proposed to overcome them, which will benefit in developing high performance next-generation rechargeable Li-ion batteries.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

8

Vallachira, Warriam Sasikumar Pradeep. „Study of Silicon Oxycarbide(SiOC) as Anode Materials for Li-ion Batteries“. Doctoral thesis, Università degli studi di Trento, 2013. https://hdl.handle.net/11572/368129.

Der volle Inhalt der Quelle

Annotation:

The principal object of this thesis is the investigation of silicon oxycarbide (SiOC) ceramics as anode material for Li-ion batteries. The investigated materials are prepared by cross linking commercial polymer siloxanes via hydrosylilation reactions or hybrid alkoxide precursors via sol-gel. The cross linked polymer networks are then converted in to ceramic materials by a pyrolysis process in controlled argon atmosphere at 800-1300 Â°C. In details the influence of carbon content on lithium storage properties is addressed for SiOC with the same O/Si atomic ratio of about 1. Detailed structural characterization studies are performed using complementary techniques which aim correlating the electrochemical behavior with the microstructure of the SiOC anodes. Results suggest that SiOC anodes behave as a composite material consisting of a disordered silicon oxycarbide phase having a very high first insertion capacity of ca 1300 mAh g-1 and a free C phase. However, the charge irreversibly trapped into the amorphous silicon oxycarbide network is also high. In consequence the maximum reversible lithium storage capacity of 650 mAh g-1 is measured on high-C content SiOCs with the ratio between amorphous silicon oxycarbide and the free C phase of ï ¾ 1:1. The high carbon content SiOC shows also an excellent cycling stability and performance at high charging/discharging rate with the stable capacity at 2C rate being around 200 mAh g-1. Increasing the pyrolysis temperature has an opposite effect on the low-C and high-C materials: for the latter one the reversible capacity decreases following a known trend while the former shows an increase of xi the reversible capacity which has never been observed before for similar materials. The influence of pyrolysis atmosphere on lithium storage capacity is investigated as well. It is found that pyrolysis in Ar/H2 mixtures, compared to the treatment under pure Ar, results into a decrease of the concentration of C dangling bonds as revealed by electron spin resonance (ESR) measurements. The sample prepared under Ar/H2 mixture shows an excellent cycling stability with an increase in the specific capacity of about 150 mAh g-1 compared to its analogues pyrolysed in pure argon atmosphere. In order to study the role of porosity towards the lithium storage properties, a comparison of dense and porous materials obtained using same starting precursors is made. Porous SiOC ceramics are prepared by HF etching of the SiOC ceramics. HF etching removes a part of the amorphous silica phase from SiOC nanostructure leaving a porous structure. Porous ceramics with surface areas up to 640 m2 g-1 is obtained. The electrochemical charging/discharging results indicate that the porosity can help to increase the lithium storage capacity and it also leads to an enhanced cycling stability. This work demonstrates clearly that silicon oxycarbide (SiOC) ceramics present excellent electrochemical properties to be applied as a promising anode material for lithium storage applications.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

9

Vallachira, Warriam Sasikumar Pradeep Pradeep. „Study of Silicon Oxycarbide(SiOC) as Anode Materials for Li-ion Batteries“. Doctoral thesis, University of Trento, 2013. http://eprints-phd.biblio.unitn.it/1112/1/PhD_Thesis_Vallachira_Pradeep.pdf.

Der volle Inhalt der Quelle

Annotation:

The principal object of this thesis is the investigation of silicon oxycarbide (SiOC) ceramics as anode material for Li-ion batteries. The investigated materials are prepared by cross linking commercial polymer siloxanes via hydrosylilation reactions or hybrid alkoxide precursors via sol-gel. The cross linked polymer networks are then converted in to ceramic materials by a pyrolysis process in controlled argon atmosphere at 800-1300 °C. In details the influence of carbon content on lithium storage properties is addressed for SiOC with the same O/Si atomic ratio of about 1. Detailed structural characterization studies are performed using complementary techniques which aim correlating the electrochemical behavior with the microstructure of the SiOC anodes. Results suggest that SiOC anodes behave as a composite material consisting of a disordered silicon oxycarbide phase having a very high first insertion capacity of ca 1300 mAh g-1 and a free C phase. However, the charge irreversibly trapped into the amorphous silicon oxycarbide network is also high. In consequence the maximum reversible lithium storage capacity of 650 mAh g-1 is measured on high-C content SiOCs with the ratio between amorphous silicon oxycarbide and the free C phase of  1:1. The high carbon content SiOC shows also an excellent cycling stability and performance at high charging/discharging rate with the stable capacity at 2C rate being around 200 mAh g-1. Increasing the pyrolysis temperature has an opposite effect on the low-C and high-C materials: for the latter one the reversible capacity decreases following a known trend while the former shows an increase of xi the reversible capacity which has never been observed before for similar materials. The influence of pyrolysis atmosphere on lithium storage capacity is investigated as well. It is found that pyrolysis in Ar/H2 mixtures, compared to the treatment under pure Ar, results into a decrease of the concentration of C dangling bonds as revealed by electron spin resonance (ESR) measurements. The sample prepared under Ar/H2 mixture shows an excellent cycling stability with an increase in the specific capacity of about 150 mAh g-1 compared to its analogues pyrolysed in pure argon atmosphere. In order to study the role of porosity towards the lithium storage properties, a comparison of dense and porous materials obtained using same starting precursors is made. Porous SiOC ceramics are prepared by HF etching of the SiOC ceramics. HF etching removes a part of the amorphous silica phase from SiOC nanostructure leaving a porous structure. Porous ceramics with surface areas up to 640 m2 g-1 is obtained. The electrochemical charging/discharging results indicate that the porosity can help to increase the lithium storage capacity and it also leads to an enhanced cycling stability. This work demonstrates clearly that silicon oxycarbide (SiOC) ceramics present excellent electrochemical properties to be applied as a promising anode material for lithium storage applications.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

10

VERSACI, DANIELE. „Materials for high energy Li-ion and post Li-ion batteries“. Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2896992.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

11

Thoss, Franziska. „Amorphe, Al-basierte Anodenmaterialien für Li-Ionen-Batterien“. Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-119680.

Der volle Inhalt der Quelle

Annotation:

Hochleistungsfähige Lithium-Ionen-Batterien sind insbesondere von der hohen spezifischen Kapazität ihrer Elektrodenmaterialien abhängig. Intermetallische Phasen sind vielversprechende Kandidaten für alternative Anodenmaterialien mit verbesserten spezifischen Kapazitäten (LiAl: 993 Ah/kg; Li22Si5: 4191 Ah/kg) gegenüber den derzeit vielfach verwendeten Kohlenstoff-Materialien (LiC6: 372 Ah/kg). Nachteilig ist jedoch, dass die kristallinen Phasenumwandlungen während der Lade-Entlade-Prozesse Volumenänderungen von 100-300% verursachen. Durch die Sprödigkeit der intermetallischen Phasen führt dies zum Zerbrechen des Elektrodenmaterials und damit zum Kontaktverlust. Um Lithiierungs- und Delithiierunsprozesse ohne kristalline Phasenumwandlungen zu realisieren und somit große Volumenänderungen zu vermeiden, wurden amorphe Al-Legierungen untersucht. In amorphe, mittels Schmelzspinnen hergestellte Legierungen (Al86Ni8La6 und Al86Ni8Y6) kann beim galvanostatischen Zyklieren nur sehr wenig Li eingelagert werden. Da kristalline Phasenumwandlungen im amorphen Zustand nicht möglich sind, wird für die Diffusion und Einlagerung von Li-Ionen ein ausreichendes freies Volumen im amorphen Atomgerüst benötigt. Die Dichtemessung der Legierungen zeigt, dass dieses freie Volumen für eine signifikante Lithiierung nicht ausreichend ist. Wird Li bereits in die amorphe Ausgangslegierung integriert, können Li-Ionen auf elektrochemischem Wege aus ihr entfernt und auch wieder eingebaut werden. Die neuartige Legierung Al43Li43Ni8Y6, die Li bereits im Ausgangszustand enthält, konnte mittels Hochenergiemahlung als amorphes Pulver hergestellt werden. Verglichen mit den Li-freien amorphen Legierungen Al86Ni8La6 bzw. Al86Ni8Y6 und ihren kristallisierten Pendants zeigt diese neu entwickelte, amorphe Legierung eine signifikant höhere Lithiierungsfähigkeit und erreicht damit eine spezifische Kapazität von ca. 800 Ah/kg bezogen auf den Al-Anteil. Durch den Abrieb des Stahlmahlbechers enthält das Pulver Al43Li43Ni8Y6 einen Fe-Anteil von ca. 15 Masse%. Dieses mit Fe verunreinigte Material zeigt besonders bei niedrigen Laderaten eine bessere Zyklenstabilität als ein im abriebfesten Siliziumnitrid-Becher gemahlenes Pulver der gleichen Zusammensetzung. Mittels Mössbauerspektroskopie wurde nachgewiesen, dass das Pulver z.T. oxidisches Fe enthält. Dieses kann über Konversionsmechanismen einen Beitrag zur spezifischen Kapazität leisten
High-energy Li-ion batteries exceedingly depend on the high specific capacity of electrode materials. Intermetallic alloys are promising candidates to be alternative anode materials with enhanced specific capacities (LiAl: 993 Ah/kg; Li22Si5: 4191 Ah/kg) in contrast to state-of-the-art techniques, dominated by carbon materials (LiC6: 372 Ah/kg). Disadvantageously the phase transitions during the charge-discharge processes, induced by the lithiation process, cause volume changes of 100-300 %. Due to the brittleness of intermetallic phases, the fracturing of the electrode material leads to the loss of the electrical contact. In order to overcome the huge volume changes amorphous Al-based alloys were investigated with the intension to realize the lithiation process without a phase transformation. Amorphous powders (Al86Ni8La6 and Al86Ni8Y6) produced via melt spinning and subsequent ball milling only show a minor lithiation during the electrochemical cycling process. This is mainly caused by the insufficient free volume, which is necessary to transfer and store Li-ions, since phase transitions are impossible in the amorphous state. If Li is already integrated into the amorphous alloy, Li-ions can easily be removed and inserted electrochemically. The new alloy Al43Li43Ni8Y6 contains Li already in its initial state and could be prepared by high energy milling as an amorphous powder. Compared with the Li-free amorphous alloys Al86Ni8La6 or Al86Ni8Y6 and their crystalline counterparts, this newly developed amorphous alloy achieves a significantly higher lithiation and therefore reaches a specific capacity of 800 Ah/kg, based on the Al-content. By the abrasion of the steel milling vials the powder contains a wear debris of 15 mass% Fe. This contaminated material shows a better cycling stability than a powder of the same composition, milled in a non-abrasive silicon nitride vial. By means of Mössbauer spectroscopy has been shown that the wear debris contains Fe oxides. This may contribute to the enhancement of the specific capacity about conversion mechanisms

APA, Harvard, Vancouver, ISO und andere Zitierweisen

12

Petr, Jakub. „Nové materiály pro Li-iontové baterie pracující na principu konverze“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220927.

Der volle Inhalt der Quelle

Annotation:

This thesis is interested in new materials for lithium – ion batteries. Two different samples were investigated, one intercalation and one conversion cathode material. The theoretical part is focused to the structure of cells, their advantages and disadvantages compared to other secondary batteries. Also other materials used in batteries are described. The practical part describes the preparation of cathode materials for subsequent testing by scanning elektron microscopy and thermogravimetric analysis. In conclusions two different materials were evaluated and compared with each other.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

13

Uitz, M., P. Bottke, W. Schmidt, M. Wark, I. Hanzu und M. Wilkening. „Li Insertion Behaviour of Rutile TiO2 Nanorods as Anode Material in Lithium-Ion Batteries“. Diffusion fundamentals 21 (2014) 23, S.1-2, 2014. https://ul.qucosa.de/id/qucosa%3A32433.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

14

Meireles, Natalia. „Separation of anode from cathode material from End of Life Li-ion batteries (LIBs)“. Thesis, Luleå tekniska universitet, Mineralteknik och metallurgi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-81356.

Der volle Inhalt der Quelle

Annotation:

With the increasing usage of electronics powered by lithium ion batteries, it is more and more importantto improve the recycling process. The current study is focused on reducing graphite content of disposedlithium batteries to aid the further treatment of the batteries. In larger picture, an increase of efficiencyleads to a less cost and less loss of material in recycling process. The approach used is to reduce graphitecontent by the agglomerated flotation, using the natural hydrophobicity of graphite. This approach candecrease the percentage of this mineral in the further recycling process of LIBs where the actual focus arethe valuable metals as lithium, cobalt, nickel and manganese. The results and conditions of flotation arecompared in cases where flotation feed material is the bulk material or thermally treated one.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

15

SPADA, DANIELE. „The key role of high-performance anode materials in Li- and Na-ion batteries“. Doctoral thesis, Università degli studi di Pavia, 2022. http://hdl.handle.net/11571/1450824.

Der volle Inhalt der Quelle

Annotation:

In questa tesi di dottorato, diversi materiali anodici per batterie agli ioni Li e Na con caratteristiche complementari sono stati studiati per avere una gamma di possibili candidati come materiali per batterie di nuova generazione. L’ossido ternario ZnFe2O4 ad alta densità di energia ha una reazione complessa e irreversibile con il Li, che è stata studiata con tecniche elettrochimiche e diffrazione operando, per comprenderne la ciclabilità. Alligazione e conversione-alligazione di Sn e SnOx sono altre reazioni elettrochimiche ad alta densità di energia, che possono essere sfruttate sia in batterie al Li che al Na. Sono stati ottenuti risultati promettenti (anche a correnti elevate) da un elettrodo composito self-standing elettrospinnato. Alte densità di potenza sono la caratteristica prevalente di FeNb11O29, le cui sorprendenti caratteristiche cinetiche sono state studiate insieme al meccanismo di reazione, grazie a diffrazione operando e spettroscopia Raman in situ.
In this PhD thesis, different anode materials for Li- and Na-ion batteries with complementary features were investigated to obtain a wide spectrum of candidate materials for next-generation batteries. The ternary transition metal oxide ZnFe2O4 offers high energy density, and its complex and irreversible reaction with Li was studied with electrochemical techniques and operando X-ray diffraction in order to understand the cycling behaviour of the material. Alloying and conversion-alloying of tin and tin oxides are also high energy density electrochemical reactions, that can be exploited in both Li- and Na-ion batteries. Promising results were obtained from an electrospun self-standing tin/carbon composite with enhanced rate capability. Higher power densities are shown by complex niobium oxides such as FeNb11O29, whose enhanced kinetic features were studied alongside the reaction mechanism, that was unravelled with operando X-ray diffraction and in situ Raman spectroscopy.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

16

Kyeremateng, Nana Amponsah. „Advanced materials based on titania nanotubes for the fabrication of high performance 3D li-ion microbatteries“. Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4772/document.

Der volle Inhalt der Quelle

Annotation:

Le développement des dispositifs microélectroniques a dopé la recherche dans le domaine des microbatteries tout solide rechargeables. Mais actuellement, les performances de ces microbatteries élaborées par des technologies couche mince (2D) sont limitées et le passage à une géométrie 3D adoptant le concept “Li-ion” ou“rocking chair” est incontournable. Cette dernière condition implique de combiner des matériaux de cathode comme LiCoO2, LiMn2O4 or LiFePO4 avec des anodes pouvant réagir de manière réversible avec les ions lithium. Parmi tous les matériaux pouvant servir potentiellement d'anode, les nanotubes de TiO2 révèlent des propriétés intéressantes pour concevoir des microbatteries Li-ion 3D. Facilement réalisable, la nano-architecture auto-organisée a montré des résultats très prometteurs en termes de capacités à des cinétiques relativement modérées. L'utilisation des nanotubes de TiO2 en tant qu'anode conduit à des cellules présentant de faible autodéchargeet élimine le risque de surcharge grâce au haut potentiel de fonctionnement (1.72 V vs. Li+/Li). Dans ce travail de thèse, nous avons étudié la substitution des ions Ti4+ par Sn4+ et Fe2+ dans les nanotubes de TiO2. Bien que la présence d'ions Fe2+ n'ait pas amélioré les performances électrochimiques des nanotubes, nous avons pu mettre en évidence l'effet bénéfique des ions Sn4+. Nous avons aussi pu montré que la fabrication de matériaux composites à base de nanotubes de TiO2 et d'oxyde de métaux de transition électrodéposés se présentant sous forme de particules (NiO et Co3O4 ) augmentait les capacités d'un facteur 4
The advent of modern microelectronic devices has necessitated the search for high-performance all-solid-state (rechargeable) microbatteries. So far, only lithium-based systems fulfill the voltage and energy density requirements of microbatteries. Presently, there is a need to move from 2D to 3D configurations, and also a necessity to adopt the “Li-ion” or the “rocking-chair” concept in designing these lithium-based (thin-film) microbatteries. This implies the combination of cathode materials such as LiCoO2, LiMn2O4 or LiFePO4 with the wide range of possible anode materials that can react reversibly with lithium. Among all the potential anode materials, TiO2 nanotubes possess a spectacular characteristic for designing 3D Li-ion microbatteries. Besides the self-organized nano-architecture, TiO2 is non-toxic and inexpensive, and the nanotubes have been demonstrated to exhibit very good capacity retention particularly at moderate kinetic rates. The use of TiO2 as anode provides cells with low self-discharge and eliminates the risk of overcharging due to its higher operating voltage (ca. 1.72 V vs. Li+/Li). Moreover, their overall performance can be improved. Hence, TiO2 nanotubes and their derivatives were synthesized and characterized, and their electrochemical behaviour versus lithium was evaluated in lithium test cells. As a first step towards the fabrication of a 3D microbattery based on TiO2 nanotubes, electrodeposition of polymer electrolytes into the synthesized TiO2 nanotubes was also studied; the inter-phase morphology and the electrochemical behaviour of the resulting material were studied

APA, Harvard, Vancouver, ISO und andere Zitierweisen

17

Yalamanchili, Anurag. „Insights into the morphological changes undergone by the anode in the lithium sulphur battery system“. Thesis, Uppsala universitet, Strukturkemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-236378.

Der volle Inhalt der Quelle

Annotation:

In this thesis, the morphological changes of the anode surface in lithium sulphur cell, during early cycling, were simulated using symmetrical lithium electrode cells with dissolved polysulphides (PS) in the electrolyte. Electron microscopy (SEM) was used as the principal investigation technique to study and record the morphological changes. The resulting images from the SEM were analysed and discussed. The initial surface structure of the lithium anode largely influenced the ensuing morphological changes taking place through lithium dissolution (pits) and lithium deposition (dendrites) during discharge and charge respectively. The rate of lithium dissolution and deposition was found to be linearly proportional to the current density applied to the cell and the effect of cycling on the anode was proportional to the total charge of the cell in general in agreement with the expected reaction. The effect of self-discharge on the anode was also studied using photoelectron spectroscopy (XPS) in tandem with SEM. The results indicated that self-discharge, occurring in the form of corrosion of the anode SEI by PS reduction, was influenced by the altered morphology of the cell after cycling. The findings presented in this project can be understood as a preliminary description for the morphological changes in the anode and their influence in the performance of lithium sulphur battery, which can be further investigated by more advanced methods.

Joint collaboration project between Scania CV AB and Uppsala University.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

18

Tranchot, Alix. „Etude par émission acoustique et dilatométrie d'électrodes à base de silicium pour batteries Li-ion“. Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI101/document.

Der volle Inhalt der Quelle

Annotation:

Afin d’augmenter la densité d’énergie des batteries Li-ion, en particulier pour le marché des véhicules électriques, il est nécessaire de développer des matériaux d’électrode plus performants. Le silicium, dont la capacité spécifique (3579mAh/g) est dix fois supérieure à celle du graphite, est un matériau particulièrement prometteur. Néanmoins, lors de sa lithiation, il subit une forte expansion volumique (280% contre 10% pour le graphite) conduisant à la décrépitation des particules de Si et à la fissuration/décohésion de l’électrode. Il en résulte une diminution notable de la durée de vie de l’anode. Pour améliorer la tenue au cyclage des électrodes, il est nécessaire de bien comprendre/quantifier leur dégradation morphologique, ce que permettent difficilement des analyses post mortem conventionnelles. Notre objectif est d’utiliser et de développer des outils permettant d'étudier in operando la dégradation de ces électrodes. Nous avons mis en œuvre des protocoles de caractérisation in operando couplant des mesures électrochimiques à l’émission acoustique d’une part et à la dilatométrie d’autre part. Le suivi de l’activité acoustique au cours du cyclage de l’électrode a montré que les particules de Si micrométrique constituant cette électrode se fracturent dès le début de la lithiation, et que la fissuration de l’électrode se produit progressivement tout au long de la 1ère lithiation. Peu d’activité acoustique est détectée par la suite. Par l’analyse des signaux acoustiques, trois types de signaux ont été identifiés, se différenciant principalement selon leur fréquence de pic. Les signaux de hautes fréquences sont associés principalement aux micro-fractures des particules en début de lithiation, et les signaux à moyennes et basses fréquences sont respectivement attribuées à la fissuration de l’électrode et aux macro-fractures des particules de Si en fin de lithiation. L’étude dilatométrique a montré une expansion volumique maximale de ~170% avec une encre tamponnée à pH3 versus 300% si l’électrode est préparée à pH7. Cette différence s’explique par la formation de liaisons cohésives entre le liant CMC et les particules de Si lorsque l’électrode est préparée à pH 3, améliorant sa résistance mécanique. Ce qui a été confirmé par des mesures d’indentation. Ainsi, l’électrode formulée à pH 3 montre une meilleure cyclabilité. Enfin, nous avons démontré qu’une diminution notable de la durée de vie de l’électrode est observée lorsque la taille initiale des particules de Si est réduite de 230 à 85nm. Nous expliquons ce résultat inattendu par une quantité insuffisante de CMC par rapport à la surface spécifique plus élevée des particules de taille plus faible. De fait, sa résistance mécanique est insuffisante et conduit à une fissuration et une exfoliation importantes de l’électrode. Ceci est appuyé par les mesures de dilatométrie, d’émission acoustique et des observations MEB
To increase the energy density of Li-ion batteries, especially for the electric vehicle market, the development of new electrode materials is required. Silicon is a particularly interesting material, thanks to its high specific capacity (3579mAh/g, ten times higher than the capacity of graphite). Nevertheless, upon lithiation, silicon undergoes an important expansion (300% vs 10% for graphite). This leads to the cracking of the Si particles and fracturing of the electrode film. These induces electrical disconnections upon cycling, resulting in a poor cycle life. To improve the cyclability of the Si based electrodes, it is important to better understand/quantify their mechanical degradation. Conventional post mortem analyses are insufficient for that purpose. The objective of this work is to develop and use in operando analyses techniques. Therefore, we established protocols to characterize composite electrodes by electrochemical measurements coupled with either acoustic emission (AE) or dilatometry measurements. The evolution of the acoustic activity upon cycling showed that the cracking of the micrometric Si particles and of the composite film mainly occurs during the first cycle and is initiated in the early stage of the lithiation. Very few AE signals are detected in the following cycles. The signal analysis leads to the identification of three types of signals depending to their peak frequency. High frequency signals were associated with surface micro-cracking of the Si particles at the beginning of lithiation. Medium and low frequency signals were respectively attributed to the fracturing of the electrode film and bulk macro-cracking of the Si particles at the end of lithiation. An electrode thickness expansion of 170% was measured by electrochemical dilatometry for our electrodes prepared at pH3 versus 300% for electrodes prepared at pH7. The different mechanical behavior is explained by the formation of covalent bonds between the CMC binder and Si particles at pH3, which increases the mechanical stability of electrodes. This was confirmed by the measurement of their hardness and Young’s modulus. Therefore, pH3 electrodes display a higher capacity retention. It was also demonstrated that a decrease of the Si particle size does not necessarily lead to an improvement of the electrode cycle life. Indeed, we observed a significant decrease of the electrode cycle life when the Si particle size is decreased from 230 to 85 nm. This can be explained by a lack of CMC binder in relation with the higher surface area of the smaller Si particles, leading to a lower mechanical resistance of the electrode film. Within the first cycles, Si 85 nm based electrodes suffer from important cracking and exfoliation. This was confirmed by in operando dilatometry and acoustic measurements, and post mortem SEM observations

APA, Harvard, Vancouver, ISO und andere Zitierweisen

19

Bordes, Arnaud. „Etude de l'insertion du lithium dans des électrodes à base de silicium. Apports de l'analyse de surface (XPS, AES, ToF-SIMS)“. Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066530/document.

Der volle Inhalt der Quelle

Annotation:

Le silicium est un matériau étudié depuis plusieurs années comme une sérieuse alternative au graphite dans les batteries Li-ion. Ce travail de thèse vise à développer des approches alternatives et complémentaires à celles déjà existantes afin de mieux comprendre les mécanismes de lithiation et de dégradation. L'analyse croisée entre plusieurs techniques, principalement FIB-ToF-SIMS, Auger, XPS et FIB-MEB, point central de l'étude, nécessite la mise en place de protocoles spécifiques prenant en compte la forte réactivité des échantillons lithiés. En premier lieu, un couplage entre ToF-SIMS et XPS sur des couches minces de silicium, permet de mettre en évidence la présence d'une phase riche en lithium ségrégée à l'interface entre la couche de matériau actif et le collecteur de courant en cuivre. Un mécanisme particulier de lithiation du silicium, basé sur l'existence de chemins de diffusion rapide pour le lithium, est suggéré. La réalisation de coupes FIB effectuées in situ dans la chambre d'analyse du ToF-SIMS sur des électrodes à base de poudre micrométrique de Si permet ensuite de proposer un mécanisme de lithiation analogue à celui mis en évidence précédemment. En outre, la présence de grains déconnectés du réseau percolant de l'électrode au cours du cyclage et piégeant le lithium est mise en évidence et contribue à la défaillance rapide de la batterie. Enfin, la méthodologie développée est appliquée à l'étude d'électrodes composées de Si nanométrique et de composite Si/C. Elle participe à l'établissement d'un modèle de croissance de SEI à la surface de grains de silicium nanométriques et permet d'identifier les raisons de la défaillance de ces électrodes
Silicon is a serious option to replace graphite in anodes for Li-ion batteries since it offers a specific capacity almost ten times higher. However, silicon anodes suffer from a drastic capacity fading, making it unusable after a few cycles. The work presented here aims at the development of new alternative and complementary approaches to those currently used, in order to better understand lithiation and degradation mechanisms. These methods are based on cross-analysis between several surface characterizations techniques, including FIB-ToF-SIMS, AES, XPS and FIB-MEB, which require specific procedures to deal with the extreme sensitivity of lithiated materials. Coupling XPS and ToF-SIMS on silicon thin films revealed the presence of a Li-rich phase segregated at the interface between silicon and Cu current collector. A mechanism based on fast diffusion paths for lithium is suggested. In situ FIB milling, performed in the analysis chamber of the ToF-SIMS on anodes using micrometer-sized silicon particles, revealed a similar mechanism involving fast diffusion paths for lithium. Additional TEM observations suggest that, in the case of micrometer-sized particles, these paths result from sub-grain boundaries. Additionally, the presence of Li trapped in Si particles which are disconnected from the conductive grid along cycling is shown, contributing to the poor battery lifespan. Finally, the developed method has been applied to electrodes based on nanometer-sized Si particles and Si/C composite. Despite of the small size of the involved particles, it is possible to get information about SEI growth on the surface of nano-sized silicon particles and to identify causes of failure

APA, Harvard, Vancouver, ISO und andere Zitierweisen

20

Nordh, Tim. „Li4Ti5O12 as an anode material for Li ion batteries in situ XRD and XPS studies“. Thesis, Uppsala universitet, Strukturkemi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-196056.

Der volle Inhalt der Quelle

Annotation:

This thesis examines parts of the kinetics and performance in Li-battery cells using lithium titanate anodes and lithium manganese oxide cathodes. Lithium titanate (Li4Ti5O12) is a candidate for battery applications in automotive vehicles due to its long lifetime and its suggested zero-strain ability. The zero-strain ability, meaning no volume changes in the material during cycling, would allow for the high charge/discharge rates required in electric vehicles. Two approaches of analysis have been performed. In situ XRD-analysis was used to verify the zero-strain ability of lithium titanate and XPS studies were used to analyze the surface chemistry of lithium titanate after cycling. It is known that lithium titanate/lithium manganeseoxide battery cells suffer from abnormal gas evolution and power degradation, and it is therefore of interest to find ways to prevent this. To be able to find methods of preventing the performance degradation deeper understanding of the kinetics are needed, since the mechanism behind this is not fully understood. The results in this thesis strengthen the understanding of lithium titanate as a zero-strain material. Furthermore, it is seen that the performance degradation possibly can be avoided or postponed by ALD deposition of aluminium oxide on the surface of the lithium manganese oxide electrode.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

21

Vanpeene, Victor. „Étude par tomographie RX d'anodes à base de silicium pour batteries Li-ion“. Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI023/document.

Der volle Inhalt der Quelle

Annotation:

De par sa capacité spécifique théorique dix fois plus élevée que celle du graphite actuellement utilisé comme matériau actif d'anode pour les batteries Li-ion, le silicium peut jouer un rôle important dans l'augmentation de la densité d'énergie de ces systèmes. La réaction d'alliage mise en place lors de sa lithiation se traduit cependant par une forte expansion volumique du silicium (~300 % contre seulement ~10 % pour le graphite), conduisant à la dégradation structurale de l'électrode, affectant notablement sa tenue au cyclage. Comprendre en détail ces phénomènes de dégradation et développer des stratégies pour limiter leur impact sur le fonctionnement de l'électrode présentent un intérêt indéniable pour la communauté scientifique du domaine. L'objectif de ces travaux de thèse était en premier lieu de développer une technique de caractérisation adaptée à l'observation de ces phénomènes de dégradation et d'en tirer les informations nécessaires pour optimiser la formulation des anodes à base de silicium. Dans ce contexte, nous avons utilisé la tomographie aux rayons X qui présente l'avantage d'être une technique analytique non-destructive permettant le suivi in situ et en 3D des variations morphologiques s'opérant au sein de l'électrode lors de son fonctionnement. Cette technique a pu être adaptée à l'étude de cas du silicium en ajustant les volumes d'électrodes analysés, la résolution spatiale et la résolution temporelle aux phénomènes à observer. Des procédures de traitement d'images adéquates ont été appliquées afin d'extraire de ces analyses tomographiques un maximum d'informations qualitatives et quantitatives pertinentes sur leur variation morphologique. De plus, cette technique a pu être couplée à la diffraction des rayons X afin de compléter la compréhension de ces phénomènes. Nous avons ainsi montré que l'utilisation d'un collecteur de courant 3D structurant en papier carbone permet d'atténuer les déformations morphologiques d'une anode de Si et d'augmenter leur réversibilité en comparaison avec un collecteur de courant conventionnel de géométrie plane en cuivre. Nous avons aussi montré que l'utilisation de nanoplaquettes de graphène comme additif conducteur en remplacement du noir de carbone permet de former un réseau conducteur plus à même de supporter les variations volumiques importantes du silicium. Enfin, la tomographie RX a permis d'étudier de façon dynamique et quantitative la fissuration et la délamination d'une électrode de Si déposée sur un collecteur de cuivre. Nous avons ainsi mis en évidence l'impact notable d'un procédé de "maturation" de l'électrode pour minimiser ces phénomènes délétères de fissuration-délamination de l'électrode
Because of its theoretical specific capacity ten times higher than that of graphite currently used as active anode material for Li-ion batteries, silicon can play an important role in increasing the energy density of these systems. However, the alloying reaction set up during its lithiation results in a high volume expansion of silicon (~300% compared with only ~10% for graphite) leading to the structural degradation of the electrode, which is significantly affecting its cycling behavior. Understanding in detail these phenomena of degradation and developing strategies to limit their impact on the functioning of the electrode are of undeniable interest for the scientific community of the field. The objective of this thesis work was first to develop a characterization technique adapted to the observation of these degradation phenomena and to draw the necessary information to optimize the formulation of silicon-based anodes. In this context, we have used X-ray tomography which has the advantage of being a non-destructive analytical technique allowing in situ and 3D monitoring of the morphological variations occurring within the electrode during its operation. This technique has been adapted to the case study of silicon by adjusting the analyzed electrode volumes, the spatial resolution and the temporal resolution to the phenomena to be observed. Appropriate image processing procedures were applied to extract from these tomographic analyzes as much qualitative and quantitative information as possible on their morphological variation. In addition, this technique could be coupled to X-ray diffraction to complete the understanding of these phenomena. We have shown that the use of a carbon paper structuring 3D current collector makes it possible to attenuate the morphological deformations of an Si anode and to increase their reversibility in comparison with a conventional copper current collector of plane geometry. We have also shown that the use of graphene nanoplatelets as a conductive additive to replace carbon black can form a conductive network more able to withstand the large volume variations of silicon. Finally, the X-ray tomography allowed studying dynamically and quantitatively the cracking and delamination of an Si electrode deposited on a copper collector. We have thus demonstrated the significant impact of a process of "maturation" of the electrode to minimize these deleterious phenomena of cracking-delamination of the electrode

APA, Harvard, Vancouver, ISO und andere Zitierweisen

22

Ezzedine, Mariam. „Fabrication of hierarchical hybrid nanostructured electrodes based on nanoparticles decorated carbon nanotubes for Li-Ion batteries“. Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX105/document.

Der volle Inhalt der Quelle

Annotation:

Cette thèse est consacrée à la fabrication ascendante (bottom-up) de matériaux nanostructurés hybrides hiérarchisés à base de nanotubes de carbone alignés verticalement (VACNTs) décorés par des nanoparticules (NPs). En fonction de leur utilisation comme cathode ou anode, des nanoparticules de soufre (S) ou silicium (Si) ont été déposées. En raison de leur structure unique et de leurs propriétés électroniques, les VACNTs agissent comme une matrice de support et un excellent collecteur de courant, améliorant ainsi les voies de transport électroniques et ioniques. La nanostructuration et le contact du S avec un matériau hôte conducteur améliore sa conductivité, tandis que la nanostructuration du Si permet d'accommoder plus facilement les variations de volume pendant les réactions électrochimiques. Dans la première partie de la thèse, nous avons synthétisé des VACNTs par une méthode de dépôt chimique en phase vapeur (HF-CVD) directement sur des fines feuilles commerciales d'aluminium et de cuivre sans aucun prétraitement des substrats. Dans la deuxième partie, nous avons décoré les parois latérales des VACNTs avec différents matériaux d'électrode, dont des nanoparticules de S et de Si. Nous avons également déposé et caractérisé des nanoparticules de nickel (Ni) sur les VACNTs en tant que matériaux alternatifs pour l'électrode positive. Aucun additif conducteur ou aucun liant polymère n'a été ajouté à la composition d'électrode. La décoration des nanotubes de carbone a été effectuée par deux méthodes différentes: méthode humide par électrodéposition et méthode sèche (par dépôt physique en phase vapeur (PVD) ou par CVD). Les structures hybrides obtenues ont été testées électrochimiquement séparément dans une pile bouton contre une contre-électrode de lithium. A notre connaissance, il s'agit de la première étude de l'évaporation du soufre sur les VACNTs et de la structure résultante (appelée ici S@VACNTs). Des essais préliminaires sur les cathodes nanostructurées obtenues (S@VACNTs revêtus d'alumine ou de polyaniline) ont montré qu'il est possible d'atteindre une capacité spécifique proche de la capacité théorique du soufre. La capacité surfacique de S@VACNTs, avec une masse de S de 0.76 mg cm-2, à un régime C/20 atteint une capacité de 1.15 mAh cm-2 au premier cycle. Pour les anodes nanostructurées au silicium (Si@VACNTs), avec une masse de Si de 4.11 mg cm-2, on montre une excellente capacité surfacique de 12.6 mAh cm-2, valeur la plus élevée pour les anodes à base de silicium nanostructurées obtenues jusqu'à présent. Dans la dernière partie de la thèse, les électrodes nanostructurées fabriquées ont été assemblées afin de réaliser la batterie complète (Li2S/Si) et sa performance électrochimique a été testée. Les capacités surfaciques obtenues pour les électrodes nanostructurées de S et de Si ouvrent la voie à la réalisation d'une LIB à haute densité d'énergie, entièrement nanostructurée, et démontrent le grand potentiel du concept proposé à base d'électrodes nanostructurées hybrides hiérarchisées
This thesis is devoted to the bottom-up fabrication of hierarchical hybrid nanostructured materials based on active vertically aligned carbon nanotubes (VACNTs) decorated with nanoparticles (NPs). Owing to their unique structure and electronic properties, VACNTs act as a support matrix and an excellent current collector, and thus enhance the electronic and ionic transport pathways. The nanostructuration and the confinement of sulfur (S) in a conductive host material improve its conductivity, while the nanostructuration of silicon (Si) accommodates better the volume change during the electrochemical reactions. In the first part of the thesis, we have synthesized VACNTs by a hot filament chemical vapor deposition (HF-CVD) method directly over aluminum and copper commercial foils without any pretreatment of the substrates. In the second part, we have decorated the sidewalls and the surface of the VACNT carpets with various LIB's active electrode materials, including S and Si NPs. We have also deposited and characterized nickel (Ni) NPs on CNTs as alternative materials for the cathode electrode. No conductive additives or any polymer binder have been added to the electrode composition. The CNTs decoration has been done systematically through two different methods: wet method by electrodeposition and dry method by physical vapor deposition (PVD). The obtained hybrid structures have been electrochemically tested separately in a coin cell against a lithium counter-electrode. Regarding the S evaporationon VACNTs, and the S@VACNTs structure, these topics are investigated for the first time to the best of our knowledge.Preliminary tests on the obtained nanostructured cathodes (S@VACNTs coated with alumina or polyaniline) have shown that it is possible to attain a specific capacity close to S theoretical storage capacity. The surface capacity of S@VACNTs, with 0.76 mg cm-2 of S, at C/20 rate reaches 1.15 mAh cm-2 at the first cycle. For the nanostructured anodes Si@VACNTs, with 4.11 mg cm-2 of Si showed an excellent surface capacity of 12.6 mAh cm-2, the highest value for nanostructured silicon anodes obtained so far. In the last part of the thesis, the fabricated nanostructured electrodes have been assembled in a full battery (Li2S/Si) and its electrochemical performances experimentally tested. The high and well-balanced surface capacities obtained for S and Si nanostructured electrodes pave the way for realization of high energy density, all-nanostructured LIBs and demonstrate the large potentialities of the proposed hierarchical hybrid nanostructures' concept

APA, Harvard, Vancouver, ISO und andere Zitierweisen

23

Bryngelsson, Hanna. „Insights into Stability Aspects of Novel Negative Electrodes for Li-ion Batteries“. Doctoral thesis, Uppsala universitet, Institutionen för materialkemi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8537.

Der volle Inhalt der Quelle

Annotation:

Demands for high energy-density batteries have sharpened with the increased use of portable electronic devices, as has the focus global warming is now placing on the need for electric and electric-hybrid vehicles. Li-ion battery technology is superior to other rechargeable battery technologies in both energy- and power-density. A remaining challenge, however, is to find an alternative candidate to graphite as the commercial anode. Several metals can store more lithium than graphite, e.g., Al, Sn, Si and Sb. The main problem is the large volume changes that these metals undergo during the lithiation process, leading to degradation and pulverization of the anode with resulting limitations in cycle-life. The Li-ion battery is studied in this thesis with the goal of better understanding the critical parameters determining high and stable electrochemical performance when using a metal or a metal-alloy anode. Various antimony-containing systems will be presented. These represent different routes to circumvent the problems caused by volume change. Sb-compounds exhibit a high lithium storage capability. At most, three Li-ions can be stored per Sb atom, leading to a theoretical gravimetric capacity of 660 mAh/g. Model systems with stepwise increasing complexity have been designed to better understand the factors influencing lithium insertion/extraction. It is demonstrated that the microstructure of the anode material is crucial to stable cycling performance and high reversibility. The relative importance of the various factors controlling stability, such as particle-size, oxide content and morphology, varies strongly with the type of system studied. The cycling performance of pure Sb is improved dramatically by incorporating a second component, Sb2O3. With a critical oxide concentration of ~25%, a stable capacity close to the theoretical value of 770 mAh/g is obtained for over 50 cycles. Cu2Sb shows stable cycling performance in the absence of oxide. Cu9Sb2 has been presented for the first time as an anode material in a Li-ion battery context. Studies of the Solid Electrolyte Interphase (SEI) formed on AlSb composite electrodes show an SEI layer thinner than graphite, and with a clearly dynamic character.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

24

Zhang, Panpan. „First-Principles Study on the Mechanical Properties of Lithiated Sn Anode Materials for Li-Ion Batteries“. Thesis, Curtin University, 2019. http://hdl.handle.net/20.500.11937/76114.

Der volle Inhalt der Quelle

Annotation:

To deeply understand macroscopic failure behaviour of Sn anode materials for Li-ion batteries and make an optimization to electrode materials, based on first-principles calculation, this thesis systematically investigates evolution of mechanical properties of active materials and interfacial mechanical properties of electrode-collector interfaces during lithiation processes. The micromechanical failure mechanism of Sn anodes is given. Based on obtained interface failure mechanism, an optimization to interface properties of electrode-collector interface is further conducted by using dopants.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

25

Dorotík, David. „Deponované vrstvy na bázi olova a kobaltu pro Li-ion akumulátory“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442525.

Der volle Inhalt der Quelle

Annotation:

The diploma thesis deals with the principles of operation of lithium ion batteries and their properties when using deposited thin films. The thesis is mainly focused on the formation of thin films using the electrolytic method and subsequently testing the properties of the thin film in an electrochemical cell. The test criteria are mainly the value of the capacity of the prepared electrode and the impact of cycling on the electrode layer itself, where the deposited layer is assessed before cycling and after cycling on an SEM microscope..

APA, Harvard, Vancouver, ISO und andere Zitierweisen

26

Fransson, Linda. „Design and Characterisation of new Anode Materials for Lithium-Ion Batteries“. Doctoral thesis, Uppsala University, Department of Materials Chemistry, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-2632.

Der volle Inhalt der Quelle

Annotation:

Reliable ways of storing energy are crucial to support our modern way of life; lithium-ion batteries provide an attractive solution. The constant demand for higher energy density, thinner, lighter and even more mechanically flexible batteries has motivated research into new battery materials. Some of these will be explored in this thesis.

The main focus is placed on the development of new anode materials for lithium-ion batteries and the assessment of their electrochemical and structural characteristics. The materials investigated are: natural Swedish graphite, SnB₂O₄ glass and intermetallics such as: Cu₆Sn₅, InSb, Cu₂Sb, MnSb and Mn₂Sb. Their performances are investigated by a combination of electrochemical, in situ X-ray diffraction and Mössbauer spectroscopy techniques, with an emphasis on the structural transformations that occur during lithiation.

The intermetallic materials exhibit a lithium insertion/metal extrusion mechanism. The reversibility of these reactions is facilitated by the strong structural relationships between the parent compounds and their lithiated counterparts. Lithiation of a majority of the intermetallics in this work proceeds via an intermediate ternary phase. The intermetallic electrodes provide high volumetric capacities and operate at slightly higher voltages vs. Li/Li⁺ than graphite. This latter feature forms the basis for a safer system.

Jet-milling of natural Swedish graphite results in decreased particle and crystallite size, leading to improved performance; the capacity is close to the theoretical capacity of graphite. Jet-milled graphite also shows an enhanced ability to withstand high charging rates.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

27

Deng, Haokun. „Nanostructured Si and Sn-Based Anodes for Lithium-Ion Batteries“. Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/612405.

Der volle Inhalt der Quelle

Annotation:

Lithium-ion batteries (LIBs) are receiving significant attention from both academia and industry as one of the most promising energy storage and conservation devices due to their high energy density and excellent safety. Graphite, the most widely used anode material, with limitations on energy density, can no longer satisfy the requirements proposed by new applications. Therefore, further improvement on the electrochemical performance of anodes has been long pursued, along with the development of new anode materials. Among potential candidates, Si and Sn based anodes are believed to be the most promising. However, the dramatic volume expansion upon Li-intercalation and contraction upon Li de-intercalation cause mechanical instability, and thus cracking of the electrodes. To overcome this issue, many strategies have been explored. Among them the most efficient strategies include introduction of a nanostructure, coupled with a buffering matrix and coating with a protective film. However, although cycling life has been significantly increased using these three strategies, the capacity retention still needs improvement, especially over extensive charge-discharge cycles. In addition, more efforts are still needed to develop new fabrication methods with low costs and high efficiency. To further improve mechanical stability of electrodes, understanding of the failure mechanisms, particularly, the failure mechanisms of Si and Sn nanomaterials is essential. Therefore, some of the key factors including materials fabrication and microstructural changes during cycling are studied in this work. Hollow Si nanospheres have proved to be have a superior electrochemical performance when applied as anode materials. However, most of fabrication methods either involve use of processing methods with low throughput, or expensive temporary templates, which severely prohibits large-scale use of hollow Si spheres. This work designed a new template-free chemical synthesis method with high throughput and simple procedures to fabricate Si hollow spheres with a nanoporous surface. The characterization results showed good crystallinity and a uniform hollow sphere structure. The substructure of pores on the surface provides pathways for electrolyte diffusion and can alleviate the damage by the volume expansion during lithiation. The success of this synthesis method provides valuable inspiration for developing industrial manufacturing method of hollow Si spheres.3D graphene is the most promising matrix that can provide the necessary mechanical support to Sn and Si nanoparticles during lithiation. 2D graphene, however, results in Sn/graphene nanocomposites with a continuous capacity fade during cycling. It is anticipated that this is due to microstructural changes of Sn, however, no studies have been performed to examine the morphology of such cycled anodes. Hence, a new Sn/2D graphene nanocomposite was fabricated via a simple chemical synthesis, in which Sn nanoparticles (20-200 nm) were attached onto the graphene surface. The content of Sn was 10 wt.% and 20 wt.%. These nanopowders were cycled against pure Li-metal and, as in previous studies, a significant capacity decrease occurred during the first several cycles. Transmission and scanning electron microscopy revealed that during long term cycling electrochemical coarsening took place, which resulted in an increased Sn particle size of over 200 nm, which could form clusters that were 1 m. Such clusters result in a poor electrochemical performance since it is difficult for complete lithiation of the Sn to occur. It is hence concluded that the inability of Sn/2D graphene anodes to retain high capacities is due to coarsening that occurs during cycling. In addition to using forms of carbon to buffer the Sn expansion, it has been proposed to alloy Sn with S, which has a low redox potential vs Li⁰/Li⁺. Therefore, another new anode proposed here is that of SnS attached to graphite. The as prepared powders had a flower-like structure of the SnS alloy. Electrochemical cycling and subsequent microstructural analysis showed that after electrochemical cycling this pattern was destroyed and replaced by Sn and SnS nanoparticles. Based on the electron microscopy and XRD analysis, it was concluded that selective leaching of S occurs during lithiation of SnS particles, which results into nano SnS and Sn particles to be distributed throughout the electrolyte or SEI layer, without being able to take part in the electrochemical reactions. This mechanism has not been noted before for SnS anodes and indicates that it may not be possible to retain the initial morphology of SnS alloy during cycling, or the ability of SnS to be active throughout long term cycling. To conclude it should be stated that the goal and novelty of this thesis was (i) the fabrication of new Si, Sn/graphene and SnS/C nanostructures that can be used as anodes in Li-ion batteries and (ii) the documentation of the mechanisms that disrupt the initial structural stability of Sn/2D graphene and SnS/C anodes and result in severe capacity loss during long term cycling (over 100 cycles). These systems are of high interest to the electrochemistry community and battery developers.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

28

Luchkin, Sergey Yurevich. „Local probing of Li+ diffusion and concentration in Li-ion battery materials by scanning probe microscopy“. Doctoral thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/14825.

Der volle Inhalt der Quelle

Annotation:

Doutoramento em Ciência e Engenharia de Materiais
This thesis presents the results of Scanning Probe Microscopy (SPM) study of Li-ion battery active materials. The measurements have been performed on LiMn2O4 cathodes and graphite anodes extracted from commercial Li batteries at different states of charge and health. The study has been focused on measurements of Li spatial distribution and transport properties in the active electrode materials. Special attention has been paid to influence of fatigue caused by high C rate cycling on Li spatial distribution and local diffusion coefficient. Electrochemical Strain Microscopy (ESM) has been used to access Li transport properties at the nanoscale in LiMn2O4 cathodes. Kelvin Probe Force Microscopy (KPFM) has been used to examine Li spatial distribution in graphite anodes. ESM has been implemented and used in a single frequency mode out of the contact resonance for the first time. Signal-to-noise ratio analysis has been performed for a number of single- and multi-frequency modes used in ESM. The analysis allowed to establish criteria for a proper cantilever choice and an experimental setup for the optimized detection of surface displacements via lock-in amplifier. Transport properties of Li+ mobile ions in fresh and fatigued LiMn2O4 battery cathodes have been studied at the nanoscale via ESM using time-and voltage spectroscopies. Both Vegard and non-Vegard contributions to ESM signal have been identified in electrochemical hysteresis loops obtained on the fresh and fatigued samples. In fresh cathodes the Vegard contribution dominates the signal, while in fatigued samples different shape of hysteresis loops indicates additional contributions. Non-uniform spatial distribution of the electrochemical loop opening in LiMn2O4 particles studied in the fatigued samples indicates stronger variation of Li diffusion coefficients in fatigued samples’ as compared to the fresh one. Time spectroscopy measurements have revealed suppressed local Li diffusivity in fatigued samples by more than two orders of magnitude as compared to the fresh one. We attributed such reduction of the diffusion coefficient to the accumulation of point defects induced by high C-rate cycling and accompanied structural instability. This mechanism can be specifically important for high C-rate cycling. Li spatial distribution in fresh and fatigued graphite cathodes has been accessed via KPFM using a 2-pass amplitude modulation mode. Core-shell and mosaic surface potential structures have been observed on the fatigued and fresh anodes, respectively. The observed surface potential distributions have been attributed to the apparent Li concentration profiles in graphite. The core-shell potential distribution has been attributed to the remnant Li ions stacked in graphite particles causing irreversible capacity loss. The mosaic potential distribution has been attributed to inactive Li inside graphite at the starting stage of cycling. The results corroborate the “radial” model used to explain the specific capacity fading mechanism at high C rate cycling in Li-ion batteries.
Esta tese apresenta os resultados do estudo de Scanning Probe Microscopia (SPM) de materiais de baterias de ions de litio. As medidas foram executadas na cátodos de LiMn2O4 e ânodos de grafite extraidos de bateriais de litio comerciais em diferentes estados de carga e fadiga. O estudo concentrou-se na medição da distribuição de Li e propriedades de transporte dos materiais de eletrodo ativo. Especial atencao tem sido dada a influencia do ciclo de fadiga da elevada taxa C na distribuicao especial dos ions de Li e coeficiente de difusao. Microscopia de tensão eletroquímica (ESM) tem sido usada para acessar Li transporte propriedades em nanoescala em cátodos de LiMn2O4. Microscopia de força de sonda Kelvin (KPFM) tem sido usada para acessar a distribuição espacial de Li em anodos de grafite. ESM foi implementada e usada em um modo de única freqüência de ressonância o contato pela primeira vez. Análise de relação sinal-ruído foi feito para um número de monomodo e multimodo usados no ESM. A análise permite estabelecer critérios para um cantilever e uma instalação experimental para a detecção mais sensível de deslocamentos superficiais. Propriedades da mobilidade dos ions de lition em catodos de bateria LiMn2O4 frescos e fatigados foram estudados em nanoescala via ESM, espectroscopia de tempo e espectroscopia de tensão de transporte. Contribuições como sinal Vegard e non-Vegard ESM foram identificadas em ciclos de histerese eletroquímica obtidos em amostras frescas e fatigadas. Em cátodos frescos o sinal Vegard dominante, enquanto em amostras envelhecidas, a diferente ciclo de histerese indica contribuições adicionais. Distribuição espacial não-uniforme do ciclo aberto eletroquímico em partículas de LiMn2O4 foram estudadas nas amostras fatigadas indicando mais forte variação do coeficiente de difusão de Li das amostras fatigadas em microescala em comparação com a outra amostra. Medições de espectroscopia de tempo revelaram a ausencia de difusidade local em amostras fatigadas por mais de duas ordens de magnitude em comparação com a outra. Atribui-se tal redução do coeficiente de difusão o acúmulo de defeitos de ponto induzida pelo Ciclo de elevada taxa C e acompanhadas de instabilidade estrutural. Este mecanismo pode ser especialmente importante para ciclo de elevada taxa C. Distribuição espacial de Li em cátodos amostras fresca e fatigada grafite foi analisaa via KPFM no modo de modulação de amplitude 2-pass. Estruturas de superfícies potenciais core-shell e mosaico têm sido observadas em ânodos fatigados e frescos, respectivamente. As distribuições de superfícies potenciais observadas foram atribuídas para os perfis de concentração Li aparentes em grafite. Distribuição potencial core-shell tem sido atribuída para o ions remanescentes de Li empilhados em partículas de grafite, causando perda irreversível de capacidade. A distribuição de potencial de mosaico tem sido atribuída a Li inativo dentro do grafite na fase inicial do ciclo. Os resultados corroboram o modelo "radial" usado para explicar o mecanismo de desvanecimento de capacidade específica a alta taxa de C em baterias de íon-lítio.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

29

Si, Wenping. „Designing Electrochemical Energy Storage Microdevices: Li-Ion Batteries and Flexible Supercapacitors“. Doctoral thesis, Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-160049.

Der volle Inhalt der Quelle

Annotation:

Die Menschheit steht vor der großen Herausforderung der Energieversorgung des 21. Jahrhundert. Nirgendwo ist diese noch dringlicher geworden als im Bereich der Energiespeicherung und Umwandlung. Konventionelle Energie kommt hauptsächlich aus fossilen Brennstoffen, die auf der Erde nur begrenzt vorhanden sind, und hat zu einer starken Belastung der Umwelt geführt. Zusätzlich nimmt der Energieverbrauch weiter zu, insbesondere durch die rasante Verbreitung von Fahrzeugen und verschiedener Kundenelektronik wie PCs und Mobiltelefone. Alternative Energiequellen sollten vor einer Energiekrise entwickelt werden. Die Gewinnung erneuerbarer Energie aus Sonne und Wind sind auf jeden Fall sehr wichtig, aber diese Energien sind oft nicht gleichmäßig und andauernd vorhanden. Energiespeichervorrichtungen sind daher von großer Bedeutung, weil sie für eine Stabilisierung der umgewandelten Energie sorgen. Darüber hinaus ist es eine enttäuschende Tatsache, dass der Akku eines Smartphones jeglichen Herstellers heute gerade einen Tag lang ausreicht, und die Nutzer einen zusätzlichen Akku zur Hand haben müssen. Die tragbare Elektronik benötigt dringend Hochleistungsenergiespeicher mit höherer Energiedichte. Der erste Teil der vorliegenden Arbeit beinhaltet Lithium-Ionen-Batterien unter Verwendung von einzelnen aufgerollten Siliziumstrukturen als Anoden, die durch nanotechnologische Methoden hergestellt werden. Eine Lab-on-Chip-Plattform wird für die Untersuchung der elektrochemischen Kinetik, der elektrischen Eigenschaften und die von dem Lithium verursachten strukturellen Veränderungen von einzelnen Siliziumrohrchen als Anoden in einer Lithium-Ionen-Batterie vorgestellt. In dem zweiten Teil wird ein neues Design und die Herstellung von flexiblen on-Chip, Festkörper Mikrosuperkondensatoren auf Basis von MnOx/Au-Multischichten vorgestellt, die mit aktueller Mikroelektronik kompatibel sind. Der Mikrosuperkondensator erzielt eine maximale Energiedichte von 1,75 mW h cm-3 und eine maximale Leistungsdichte von 3,44 W cm-3. Weiterhin wird ein flexibler und faserartig verwebter Superkondensator mit einem Cu-Draht als Substrat vorgestellt. Diese Dissertation wurde im Rahmen des Forschungsprojekts GRK 1215 "Rolled-up Nanotechnologie für on-Chip Energiespeicherung" 2010-2013, finanziell unterstützt von der International Research Training Group (IRTG), und dem PAKT Projekt "Elektrochemische Energiespeicherung in autonomen Systemen, no. 49004401" 2013-2014, angefertigt. Das Ziel der Projekte war die Entwicklung von fortschrittlichen Energiespeichermaterialien für die nächste Generation von Akkus und von flexiblen Superkondensatoren, um das Problem der Energiespeicherung zu addressieren. Hier bedanke ich mich sehr, dass IRTG mir die Möglichkeit angebotet hat, die Forschung in Deutschland stattzufinden
Human beings are facing the grand energy challenge in the 21st century. Nowhere has this become more urgent than in the area of energy storage and conversion. Conventional energy is based on fossil fuels which are limited on the earth, and has caused extensive environmental pollutions. Additionally, the consumptions of energy are still increasing, especially with the rapid proliferation of vehicles and various consumer electronics like PCs and cell phones. We cannot rely on the earth’s limited legacy forever. Alternative energy resources should be developed before an energy crisis. The developments of renewable conversion energy from solar and wind are very important but these energies are often not even and continuous. Therefore, energy storage devices are of significant importance since they are the one stabilizing the converted energy. In addition, it is a disappointing fact that nowadays a smart phone, no matter of which brand, runs out of power in one day, and users have to carry an extra mobile power pack. Portable electronics demands urgently high-performance energy storage devices with higher energy density. The first part of this work involves lithium-ion micro-batteries utilizing single silicon rolled-up tubes as anodes, which are fabricated by the rolled-up nanotechnology approach. A lab-on-chip electrochemical device platform is presented for probing the electrochemical kinetics, electrical properties and lithium-driven structural changes of a single silicon rolled-up tube as an anode in lithium ion batteries. The second part introduces the new design and fabrication of on chip, all solid-state and flexible micro-supercapacitors based on MnOx/Au multilayers, which are compatible with current microelectronics. The micro-supercapacitor exhibits a maximum energy density of 1.75 mW h cm-3 and a maximum power density of 3.44 W cm-3. Furthermore, a flexible and weavable fiber-like supercapacitor is also demonstrated using Cu wire as substrate. This dissertation was written based on the research project supported by the International Research Training Group (IRTG) GRK 1215 "Rolled-up nanotech for on-chip energy storage" from the year 2010 to 2013 and PAKT project "Electrochemical energy storage in autonomous systems, no. 49004401" from 2013 to 2014. The aim of the projects was to design advanced energy storage materials for next-generation rechargeable batteries and flexible supercapacitors in order to address the energy issue. Here, I am deeply indebted to IRTG for giving me an opportunity to carry out the research project in Germany. September 2014, IFW Dresden, Germany Wenping Si

APA, Harvard, Vancouver, ISO und andere Zitierweisen

30

FATHI, REZA. „Investigation of Alkaline Ion Rocking Chair Batteries“. Doctoral thesis, Università degli Studi di Milano-Bicocca, 2015. http://hdl.handle.net/10281/77623.

Der volle Inhalt der Quelle

Annotation:

The work was devoted to the improvement of rechargeable batteries. Two different strategies were applied: i) investigation of new electrode materials to increase the battery performance, and ii) studies on failure mechanism of commercial rechargeable batteries. Both Li-ion and Na-ion systems were explored. In the former case, carbon based materials were investigated as high capacity anode (chapter 2), while the cell failure of commercial cells (chapter 3) and pouch cells (chapter 4) were investigated by Ultra High Precision Coulometry (UHPC) and dQ/dV analysis. Moreover, Na-ion systems, a low cost alternative to the Li-ion batteries, were investigated. Sn films were characterized as negative electrode (chapter 5), while Na0.44MnO2 cathode material was investigated by electrochemical techniques (chapter 6). A brief description of the aforementioned chapters is here reported. Chapter 2. Carbon films were prepared by DC magnetron sputtering at argon pressures ranging from 1 to 30 mTorr. The film sputtered at the lowest pressure was fully amorphous, and showed a density of 1.9±0.3 g/cc indicating little porosity. The film sputtered at the highest pressure showed a broad (002) Bragg peak and had a density of 1.35 ± 0.15 g/cc, indicating significant porosity. Electrochemical testing showed that the low pressure sputtered carbon had a reversible specific capacity of about 800 mAh/g, and an average delithiation potential of about 1 V vs. Li/Li+. Heating the same film to 900oC in argon decreased the reversible capacity and the average voltage to 600 mAh/g and 0.75V, respectively. Chapter 3. Commercial aged LiCoO2/Graphite cells having different cycling histories were studied. Even after 12 years of operation at 37oC, the cells still retained 80% of their initial capacity with coulombic efficiency of 0.99985 when measured at C/20 and 40oC. The capacity loss of these cells could be explained by loss of lithium inventory through growth of the solid electrolyte interphase (SEI) at the anode. There is no evidence of active material loss due to electrical disconnect in these cells. A low upper cut-off voltage (4.075 V) is crucial to the long lifetime of these cells due to electrolyte oxidation reactions at the positive electrode, revealed by the UHPC experiments. Chapter 4. Li[Ni1/3Mn1/3Co1/3]O2/graphite pouch cells were cycled at various discharge rates of C/2, C, 2C, and 4C at 30.oC. According to dV/dQ analysis there is very small, if any, active mass loss in any of these cells up to 540 cycles. All the lost capacity is due to loss of active lithium atoms in the negative electrode SEI as relative electrode slippage, derived from dV/dQ analysis, and capacity loss are nicely correlated. Scanning electron microscopy images show clear evidence of particle or/and SEI layer cracking at the negative electrode for the cells discharged at 4C, while the NMC particles were unaffected. Chapter 5. Sn films, obtained by electrodeposition, were structural and electrochemical characterized. Electrochemical potential spectroscopy (EPS) and galvanostatic cycling of the electrodes were investigated in organic electrolyte. Three crystalline and one amorphous phases were identified as well as high discharge capacity (738 mAh/g) was obtained after 4 cycles. Unfortunately material fading, due to the internal stress during cycling, causes poor cyclability. Chapter 6. Na0.44MnO2 compound was prepared by a modified Pechini method and characterized. The material exhibits a discharge capacity (about 110 mAh/g) at low current (11 mA/g) which decreases to 65 mAh/g at high current (275 mA/g). The electrochemistry was investigated by electrochemical impedance spectroscopy. It was observed that the kinetic limitations are mainly due to the low diffusion coefficient of Na+ in the structure and to the high values of the surface resistance which is the sum of two contributes attributed to the charge transfer process and the presence of a passive layer.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

31

Kang, Chi Won. „Enhanced 3-Dimensional Carbon Nanotube Based Anodes for Li-ion Battery Applications“. FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/955.

Der volle Inhalt der Quelle

Annotation:

A prototype 3-dimensional (3D) anode, based on multiwall carbon nanotubes (MWCNTs), for Li-ion batteries (LIBs), with potential use in Electric Vehicles (EVs) was investigated. The unique 3D design of the anode allowed much higher areal mass density of MWCNTs as active materials, resulting in more amount of Li+ ion intake, compared to that of a conventional 2D counterpart. Furthermore, 3D amorphous Si/MWCNTs hybrid structure offered enhancement in electrochemical response (specific capacity 549 mAhg-1). Also, an anode stack was fabricated to further increase the areal or volumetric mass density of MWCNTs. An areal mass density of the anode stack 34.9 mg/cm2 was attained, which is 1,342% higher than the value for a single layer 2.6 mg/cm2. Furthermore, the binder-assisted and hot-pressed anode stack yielded the average reversible, stable gravimetric and volumetric specific capacities of 213 mAhg-1 and 265 mAh/cm3, respectively (at 0.5C). Moreover, a large-scale patterned novel flexible 3D MWCNTs-graphene-polyethylene terephthalate (PET) anode structure was prepared. It generated a reversible specific capacity of 153 mAhg-1 at 0.17C and cycling stability of 130 mAhg-1 up to 50 cycles at 1.7C.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

32

Denoyelle, Elise. „Développement d’une microbatterie Li-ion 3D & Étude d’une anode de silicium amorphe déposée par LPCVD sur substrat 3D“. Caen, 2010. http://www.theses.fr/2010CAEN2005.

Der volle Inhalt der Quelle

Annotation:

Depuis l’avènement des premiers circuits intégrés, l’industrie du semiconducteur s’efforce sans cesse de miniaturiser la taille des composants électroniques. La société NXP conçoît depuis plusieurs années des systèmes "sb-SiP" (silicon-based System in Package) qui permettent d’intégrer les composants passifs sur une puce passive sur laquelle est montée une ou plusieurs puces actives. Ce concept repose principalement sur la technologie PICS (Passive Integration Connective Substrate) qui permet d’intégrer sur silicium des condensateurs de valeurs élevées. Devant le succès et le potentiel de ce procédé, NXP entrevoit de nouvelles applications comme les microbatteries 3D lithium-ion. Dans un premier temps, nous avons effectué une recherche de partenariat afin d’acquérir l’expertise nécessaire dans la technologie lithium-ion. Les différentes démarches investies nous ont permis de définir plus précisément les briques technologique intervenant dans le développement d’une microbatterie 3D sur substrat silicium et d’aborder le second axe de ces travaux: l’étude d’une anode de silicium amorphe déposée par LPCVD (Low Pressure Chemical Vapor Deposition). L’objectif de l’étude est d’évaluer les performances d’une anode en silicium amorphe en configuration planaire (2D) et tridimensionnelle (3D)
Since the first Integrated Circuits, the Semiconductors industry has innovated in the field of miniaturization at the device level. For several years, NXP company has designed sb-SiP systems (silicon-based System in Package) which allow the insertion of passive components into passive devices on which an active device is mounted. The concept depends upon the PICS technology (Passive Integration Connective Substrate) which allows the integration of capacitors of high values. Considering the achievement of this process, NXP wishes to develop new products as 3D Li-ion microbatteries. At first, we developed a partnership approach in order to acquire competences in lithium-ion technology. The different contacts allow us to define more precisely the technological components needed in order to create a 3D-microbattery on silicon substrate. In a second part, we adress the study of an amorphous silicon thin film anode deposited by LPCVD (Low Pressure Chemical Vapor Deposition). The objective of the study is to measure the electrochemical performances of the amorphous silicon anode on 2D and 3D silicon substrate

APA, Harvard, Vancouver, ISO und andere Zitierweisen

33

Fan, Jui Chin. „The Impact of Nanostructured Templates and Additives on the Performance of Si Electrodes and Solid Polymer Electrolytes for Advanced Battery Applications“. BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7568.

Der volle Inhalt der Quelle

Annotation:

The primary objectives of this research are: (1) use a hierarchical structure to study electrode materials for next-generation lithium-ion batteries (LIBs) and (2) understand the fundamentals and utility of solid polymer electrolytes (SPEs) with the addition of halloysite nanotubes (HNTs) for battery applications. Understanding the fundamental principles of electrode and electrolyte materials allows for the development of high-performance LIBs. The contributions of this dissertation are described below. Encapsulated Si-VACNT Electrodes. Two hurdles prevent Si-based electrodes from mass production. First, bulk Si undergoes volume expansion up to 300%. Second, a solid-electrolyte interphase (SEI) forms between the interface of the electrolyte and electrode, which consumes battery capacity and creates more resistance at the interface. Si volume changes were overcome by depositing silicon on vertically-aligned carbon nanotubes (VACNTs). Encapsulating the entire Si-VACNT electrode surface with carbon was used to mitigate SEI formation. Although SEI formation was reduced by the encapsulation layer, capacity fade was still observed for encapsulated electrodes, indicating that SEI formation was not the primary factor affecting capacity fade. Additionally, the impact of the encapsulation layer on Li transport was examined. Two different transport directions and length scales were relevant””(1) radial transport of Li in/out of each Si-coated nanotube (~40 nm diameter) and (2) Li transport along the length of the nanotubes (~10 µm height). Experimental results indicated that the height of the Si-VACNT electrodes did not limit Li transport, even though that height was orders of magnitude greater than the diameter of the tubes. Simulation and experimental data indicated that time constant for Li diffusion into silicon was slow, even though the diffusion distance was short relative to the tube height. Other factors such as diffusion-induced stress likely had a significant impact on diffusion through the thin silicon layer. Solid Polymer Electrolytes. A thorough understanding of the relationships between physical, transport, and electrochemical properties was studied. HNT addition to polyethylene oxide (PEO) electrolytes not only improved the physical properties, such as reduction of the crystallinity of PEO, but also enhanced transport properties like the salt diffusivity. The processing steps were important for achieving enhanced properties. Moreover, HNTs were found to stabilize the interfacial properties of the SPE films during cycling. Specifically, HNT-containing SPE films were successfully cycled at room temperature, which may have important implications for SPE-based batteries.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

34

Anitha, Sukkurji Parvathy [Verfasser], und W. G. [Akademischer Betreuer] Bessler. „Advanced Anode and Cathode Materials for Li-ion Batteries: Application to Printing Methodology / Parvathy Anitha Sukkurji ; Betreuer: W. G. Bessler“. Karlsruhe : KIT-Bibliothek, 2021. http://d-nb.info/1241189269/34.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

35

Lepoivre, Florent. „Study and improvement of non-aqueous Lithium-Air batteries via the development of a silicon-based anode“. Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066326/document.

Der volle Inhalt der Quelle

Annotation:

Face aux défis du XXIème siècle concernant l'approvisionnement mondial en énergie et le réchauffement climatique, il est capital de développer des systèmes de stockage d'énergie efficaces et compétitifs. Parmi eux, la technologie Lithium-Air fait l'objet de nombreuses recherches car elle présente une densité d'énergie théorique dix fois supérieure à celle des batteries Li-ion actuellement utilisées, mais la complexité des réactions chimiques mises en jeu la cantonne au stade de la recherche. Afin d'étudier de manière fiable et reproductible les batteries Li-Air, une nouvelle cellule de test électrochimique intégrant un capteur de pression a été développée. Elle permet d'estimer la quantité de réactions parasites associées à une configuration de batterie lors du cyclage à court et long terme (> 1000 h). Une étude comparative des différents électrolytes les plus utilisés a été réalisée, révélant la différence de comportement entre ces différentes espèces ainsi que l'instabilité de l'anode composée de lithium métallique. Nous avons donc abordé le remplacement de l'anode de lithium par une électrode de silicium pré-lithié. En étudiant l'influence de différentes techniques de pré-lithiation sur des électrodes contenant des particules de Si oxydées en surface, un phénomène de réduction de SiO2 en Si a été mis en évidence, apportant ainsi un gain substantiel en capacité. Les électrodes " activées " ont ensuite été utilisées en tant qu'anode dans les cellules complètes LixSi-O2. Après optimisation, la durée de vie obtenue est supérieure à 400 h (> 30 cycles), ce qui est comparable à la littérature actuelle mais toutefois limité par la présence de réactions parasites
Supplying the world energy demand while reducing the greenhouse gases emissions is one of the biggest challenges of the 21st century; this requires the development of efficient energy storage devices enabling the utilization of renewable energies. Among them, Lithium-Air batteries are very attractive due to their high theoretical energy density – 10 times that of the current Li-ion batteries – but their development is hindered by the complexity of the chemistry at play. In order to understand such chemistry, we designed a new electrochemical test cell that integrates a pressure sensor, thereby enabling an accurate in operando monitoring of the pressure changes during charge/discharge with high reproducibility and sensitivity. Its use is demonstrated by quantifying the parasitic reactions in Li-O2 cells for various electrolytes frequently encountered in the literature. Through this comparative study, we are able to observe the phenomena currently limiting the performances of Li-O2 batteries after a long cycling (> 1000 h), such as parasitic reactions and the instability of the Li anode. To address the later issue, Li was replaced by a prelithiated silicon electrode made of Si particles oxidized in surface. We demonstrated the feasibility of enhancing both their capacity and cycle life via a pre-formatting treatment that triggers the reduction of their SiO2 coating by liberating pure Si metal. The full LixSi-O2 cells using such treated electrodes exhibit performances competing with the best analogous systems reported in the literature (> 30 cycles; more than 400 h of cycling), but the development of practical prototypes still requires to improve the cycle-life

APA, Harvard, Vancouver, ISO und andere Zitierweisen

36

Sitinamaluwa, Hansinee Sakunthala. „Characterization of mechanical and electrochemical properties of silicon based electrodes for Li-ion batteries“. Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/107551/1/Hansinee%20Sakunthala_Sitinamaluwa_Thesis.pdf.

Der volle Inhalt der Quelle

Annotation:

This work aims to understand the electrochemical and mechanical behaviour of silicon thin film electrodes in Lithium-ion batteries. The evolution of microstructures, mechanical stresses and material damage have been investigated via combined experimental and molecular modelling approaches. Possible mechanisms responsible for electrochemical behaviour, volume change and material failure during charging/discharging processes have been proposed. The outcome of this work will benefit the development of novel electrode materials for high-capacity Lithium-ion batteries.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

37

Gauthier, Nicolas. „Caractérisation physico-chimique des interfaces électrode/électrolyte dans les accumulateurs lithium-ion constitués d'une anode Li4Ti5O12, de leurs vieillissements et de leurs interactions : Analyse complémentaire par XPS, ToF-SIMS et AES“. Thesis, Pau, 2019. http://www.theses.fr/2019PAUU3033.

Der volle Inhalt der Quelle

Annotation:

Le développement de l’accumulateur Li-ion et les solutions technologiques apportées pour son amélioration en matière de cyclabilité et de sécurité permettront dans le futur de généraliser son utilisation dans les véhicules électriques et de pérenniser l’approvisionnement énergétique de ces derniers. L’intégration de titanate de lithium (Li4Ti5O12), comme électrode négative alternative au graphite (électrode le plus couramment utilisé dans les systèmes commerciaux) dans les batteries Li-ion peut répondre à ces exigences. Néanmoins, des réactions parasites survenant à l’interface électrode LTO/électrolyte, au cours du cyclage de l’accumulateur, sont responsables d’une production de gaz importante et de la formation d’une couche interfaciale (appelée SEI), dont l’impact sur le fonctionnement de l’accumulateur représente un frein à son utilisation. La SEI formée sur les électrodes de LTO, est d’épaisseur de l’ordre de quelques nanomètres. De fait, les travaux réalisés ont mis à contribution la sensibilité d’extrême surface de trois techniques appropriées pour l’étude des interfaces électrode/électrolyte et de leurs interactions : la Spectroscopie Photoélectronique à rayonnement X (XPS), la microscopie Auger à balayage (SAM) et la spectrométrie de masse d’ions secondaires à temps de vol (ToF-SIMS). Les résultats présentés dans ce manuscrit sont ainsi issus de l’étude physico-chimique des interfaces électrodes/électrolyte dans les accumulateurs lithium-ion constitués d'une anode de Li4Ti5O12, de leurs vieillissements et de leurs interactions. Les électrodes positives utilisées au cours de ces travaux, composées d’oxydes tels que le LiFePO4, le LiNi3/5Mn1/5Co1/5O2 et le LiMn2O4, sont ceux habituellement intégrés dans les systèmes commerciaux. Différents paramètres susceptibles d'avoir une influence sur les performances électrochimiques de l’accumulateur et sur les propriétés de la SEI (épaisseur, composition chimique, dissolution) et notamment celle formée à l'interface électrodes LTO/électrolyte ont donc été étudiés. En particulier, la nature de l'électrode positive a été modifiée, la température de cyclage, les régimes de fonctionnement et les tensions de coupure à haut (4,6 V) et bas (0,0 V) potentiels ont été variés ainsi que la composition de l'électrolyte (d'une part le sel de lithium et d'autre part le solvant) et la composition de l’électrode de LTO elle-même
The development of the Li-ion batteries and the adapted technological solutions for their improvement in terms of cyclability and safety will allow to generalize their use in electric vehicles in the future and to perpetuate their energy supply. The use of lithium titanate (Li4Ti5O12) as an alternative negative electrode to graphite (the most commonly used electrode in commercial systems) in Li-ion batteries can complete these requirements. Nevertheless, parasitic reactions occurring at the LTO electrode/electrolyte interface, during cells cycling, are responsible for a significant gas production and the formation of a solid electrolyte interface (SEI), which highly impacts the batteries operation and performance. The SEI formed at the LTO electrodes, is of the order of a few nanometers thick. In fact, the work carried out involved the extreme surface sensitivity of three techniques suitable for the study of electrode/electrolyte interfaces and their interactions: X-ray Photoelectron Spectroscopy (XPS), scanning Auger microscopy (SAM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results, presented in this manuscript, thus come from the physicochemical study of electrode/electrolyte interfaces in lithium-ion cells consisting of a Li4Ti5O12 anode, their aging and their interactions. The positive electrodes used in this work, composed of oxides such as LiFePO4, LiNi3/5Mn1/5Co1/5O2 and LiMn2O4, are those usually incorporated into commercial systems. Various parameters that have an influence on the electrochemical performances of the accumulator and on the properties of the SEI (thickness, chemical composition, dissolution) and in particular that formed at the LTO electrode/electrolyte interface have therefore been studied. In particular, the nature of the positive electrode has been modified, the cycling temperature, the operating regimes and the high (4.6 V) and low (0.0 V) potential cut-off voltages have been varied as well as the composition of the electrolyte (on the one hand the lithium salt and on the other hand the solvent) and the composition of the LTO electrode

APA, Harvard, Vancouver, ISO und andere Zitierweisen

38

Sun, Yuandong. „REDUCED SILICA GEL FOR SILICON ANODE BASED LI-ION BATTERY AND GOLD NANOPARTICLE AT MOLYBDENUM DISULFIDE PHOTO CATALYST FOR SELECTIVE OXIDATION REACTION“. University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1490479937863989.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

39

PALUMBO, STEFANO. „Study of an off-grid wireless sensors with Li-Ion battery and Giant Magnetostrisctive Material“. Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2827717.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

40

Johnston, Matthew Gerard. „Applications of Surface Analysis Techniques to the Study of Electrochemical Systems“. Case Western Reserve University School of Graduate Studies / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=case1089811353.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

41

Kim, Il Tae. „Carbon-based magnetic nanohybrid materials for polymer composites and electrochemical energy storage and conversion“. Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45876.

Der volle Inhalt der Quelle

Annotation:

The role of nanohybrid materials in the fields of polymer composites and electrochemical energy systems is significant since they affect the enhanced physical properties and improved electrochemical performance, respectively. As basic nanomaterials, carbon nanotubes and graphene were utilized due to their outstanding physical properties. With these materials, hybrid nanostructures were generated through a novel synthesis method, modified sol-gel process; namely, carbon nanotubes (CNTs)-maghemite and reduced graphene oxide (rGO)-maghemite nanohybrid materials were developed. In the study on polymer composities, developed CNTs-maghemite (magnetic carbon nanotbues (m-CNTs)) were readily aligned under an externally applied magnetic field, and due to the aligned features of m-CNTs in polymer matrices, it showed much enhanced anisotropic electrical and mechanical properties. In the study on electrochemical energy system (Li-ion batteries), rGO-maghemite were used as anode materials; as a result, they showed improved electrochemical performance for Li-ion batteries due to their specific morphology and characteristics.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

42

Kaplenko, Oleksii. „Studium elektrodových materiálů pro Li-Ion akumulátory pomocí elektronové mikroskopie“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377024.

Der volle Inhalt der Quelle

Annotation:

The aim of this work is to describe the influence of temperature on the structure and chemical composition of electrode materials for Li-ion accumulators. Theoretical part of this thesis contains described terminology and general issues of batteries and their division. Every kind of battery is provided with a closer description of a specific battery type. A separate chapter is dedicated to lithium cells, mainly Li-ion batteries. Considering various composition of Li-ion batteries, the next subchapters deeply analyzes the most used cathode (with an emphasis on the LiFePO4, LiMn1/3Ni1/3Co1/3O2) and anode materials (with an emphasis on the Li4Ti5O12). The next chapters describe the used analytical methods: electron microscopy, energy dispersion spectroscopy and thermomechanical analysis. The practical part is devoted to the description of the individual experiments and the achieved results.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

43

Bečan, Jan. „Pokročilé uhlíkové struktury jako materiál pro Na-ion akumulátory“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442445.

Der volle Inhalt der Quelle

Annotation:

This diploma thesis deals with the description of individual types of batteries. The first part is focused to primary and secondary batteries, materials for their positive and negative electrodes with a focus on lithium-ion batteries and their changes over time. The next section focuses on a more detailed description of sodium-ion batteries, used electrode materials and to their problems. Practical part is focesed to preparing of electrode materials and to completing of measuring electrochemical cell and to discribing of measuring methodes and to evaluation of measured data.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

44

Kaspar, Jan [Verfasser], Ralf [Akademischer Betreuer] Riedel und Gian Domenico [Akademischer Betreuer] Sorarù. „Carbon-Rich Silicon Oxycarbide (SiOC) and Silicon Oxycarbide/Element (SiOC/X, X= Si, Sn) Nano-Composites as New Anode Materials for Li-Ion Battery Application / Jan Kaspar. Betreuer: Ralf Riedel ; Gian Domenico Soraru“. Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2014. http://d-nb.info/1110902336/34.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

45

Permien, Stefan [Verfasser]. „Investigation of the reaction mechanisms during Li uptake and release of spinel oxide nanoparticles MIIMIIIFeO4 (MII = Mn, Mg, Co, Ni; MIII = Mn, Fe) for application as anode materials in Lithium ion batteries / Stefan Permien“. Kiel : Universitätsbibliothek Kiel, 2017. http://d-nb.info/1123572127/34.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

46

Brumbarov, Jassen [Verfasser], Julia [Akademischer Betreuer] Kunze-Liebhäuser, Peter [Gutachter] Müller-Buschbaum und Julia [Gutachter] Kunze-Liebhäuser. „Si on conductive self-organized TiO2 nanotubes – A safe high capacity anode material for Li-ion batteries : Synthesis, physical and electrochemical characterization / Jassen Brumbarov ; Gutachter: Peter Müller-Buschbaum, Julia Kunze-Liebhäuser ; Betreuer: Julia Kunze-Liebhäuser“. München : Universitätsbibliothek der TU München, 2021. http://d-nb.info/1232406198/34.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

47

Bazin, Laurent. „Anodes nanostructurées pour microbatteries 3D Li-ion“. Toulouse 3, 2009. http://thesesups.ups-tlse.fr/815/.

Der volle Inhalt der Quelle

Annotation:

Cette thèse a pour sujet l'élaboration et la caractérisation d'anodes nano-architecturées pour des applications en microbatteries Li-ion 3D. Ces électrodes sont basées sur un collecteur de courant nano-structuré, constitué d'un tapis de nano-piliers de cuivre (Ø200nm, L=2µm) alignés verticalement. L'objectif de ce travail a été de montrer les avantages d'une électrode tridimensionnelle en revêtant ce substrat avec différents matériaux actifs en utilisant différentes techniques. De l'étain métallique Sn a pu être déposé par voie électrochimique et forme une couche conforme sur la nanostructure de cuivre. L'électrode obtenue cycle à une capacité de 0,02 mAh. Cm-2 durant plus de 500 cycles, ainsi que 75% de rétention de capacité entre 0,05 et 6C. L'alliage Cu6Sn5 formé à l'interface cuivre/étain a été identifié comme responsable de cette bonne tenue en cyclage. Suite à ce résultat, on a tenté de réaliser un dépôt conforme de matériau actif par électrophorèse (EPD). Dans un premier temps, la faisabilité de ce dépôt a été prouvée en utilisant des nanoparticules de silice SiO2. Ces expériences ont permis de mettre en lumière l'importance de la qualité de la dispersion lors d'un dépôt électrophorétique sur un substrat nanométrique de géométrie complexe. Le dépôt EPD de nanoparticules d'oxyde d'étain SnO2 a ensuite été réalisé. Les tests électrochimiques de l'anode obtenue ont montrés un comportement identique à celui de l'anode de Sn. Ceci confirme l'intérêt de la technique d'EPD pour l'élaboration d'électrodes nanostructurées
The aim of this thesis is to elaborate and characterise nano-architectured anodes for Li-ion 3D microbatteries. These electrodes are based on a nanostructured current collector, consisting in vertically-aligned arrays of copper nanopillars (Ø200nm, L=2µm). The goal of this work is to highlight the merits of a 3D electrode prepared by coating this substrate using different techniques and active materials. Tin metal has been deposited by ELD and formed a conformal layer onto the Cu current collectors. The obtained electrode showed a capacity of 0,02 mAh. Cm-2 during more than 500 cycles and a retention capacity of 75 % between 0,05 and 6C. Cu6Sn5 alloy, formed at the Cu/Sn interface was identified as responsible of this good cycling behaviour. Then, we attempted to realise a conformal coating using the electrophoretic deposition technique. In a first step, the feasibility of this deposition was proved using silica nanoparticules. These experiments enlighted the importance of the quality of the dispersion during EPD onto a nanostructured substrate. After this, an EPD depositin of SnO2 nanoparticle has been realised. Electrochemical charactyerisations of the obtained SnO2 anodes show similar behavior as Sn anodes. This confirms the interest of EPD techniques for elaboration nanostructured electrodes

APA, Harvard, Vancouver, ISO und andere Zitierweisen

48

Bascaran, Julen. „Amorphous Materials as Fast Charging Li-ion Battery Anodes“. The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1565192878407804.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

49

Beaulieu, Luc Yvon. „Mechanically alloyed Sn-Mn-C anodes for Li-ion batteries“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0016/MQ57272.pdf.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

50

KUO, YU-FAN, und 郭怡汎. „SnS-Sb2S3 as Anode Materials for Li Ion Battery“. Thesis, 2015. http://ndltd.ncl.edu.tw/handle/85993913871456952861.

Der volle Inhalt der Quelle

Annotation:

碩士
國立中央大學
化學工程與材料工程學系
103
Lithium-ion batteries (LIBs) are the most widely used rechargeable batteries for powering electronic devices such as electric vehicles (EV), laptop computers and cellular phones due to their high energy density. We proposed to use ternary Sn-Sb-S metal sulfide as the active materials for LIBs. Specifically, Sn(1)-Sb(2)-S(4) and Sn(3)-Sb(2)-S(6) were first prepared and tested as anode. It is expected that the stepwise lithium insertion mechanism can alleviate volume changes and improve the mechanical stability of the electrode. In this study, the Sn(1)-Sb(2)-S(4) and the Sn(3)-Sb(2)-S(6) powders are synthesized using solvothermal and physical mixture method. The as-prepared powders and annealed (500 oC) ones were tested. Noted that the as-prepared samples exhibited mixtures of SnS and Sb2S3. Depending on the preparation conditions, annealed samples show a major phase of SnSb2S4 and Sn3Sb2S6. Compare the Sn(1)-Sb(2)-S(4) and the Sn(3)-Sb(2)-S(6) with Sb2S3 and SnS, annealed Sn(3)-Sb(2)-S(6) powder provides the highest capacity of 829 mAh/g. However, anneaned Sn(1)-Sb(2)-S(4) powder has the best cycle stability with the reversible capacity of 164 mAh/g after 150 cycles at a constant current of 300 mA/g, corresponding to 28 % retention. In a parallel experiment, binder and electrolyte were changed to improve the capacity and retention. Here, the binder, PVdF was replaced by polyimide DB100. The electrolyte was switched from commercial electrolyte (1 M LiPF6 in EC/DEC) to 1 M LiPF6 in FEC/DEC. The capacities of ternary metal sulfide (Sn-Sb-S) were significantly enhanced, even better than that of the Sb2S3 and SnS binary metal sulfide. At a constant current of 250 mA/g, Sn(3)-Sb(2)-S(6) powder exhibits a reversible capacity of 963 mAh/g after 50 cycles with the retention of 92 %.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

Dissertationen zum Thema „Anode Li“

Geben Sie eine Quelle nach APA, MLA, Chicago, Harvard und anderen Zitierweisen an