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Hernandez, Alvarez Erick Ivan. "Electrolyte selection for cobalt-free solid-state batteries." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119602.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (page 30).
Lithium-ion batteries are widespread in use due to their thermal stability and high energy density. The most common design uses an organic electrolyte and lithium-cobalt electrode. While safe under typical operating conditions, the use of an organic electrolyte subjects the battery user to certain risks; in particular, Li-ion liquid batteries are explosive when exposed to air and subject to thermal runoff, making them highly sensitive to any physical damage. The use of cobalt also poses a moral concern, as the mining and sourcing of cobalt is geographically restricted and most commonly sourced from countries that have a history of foreign exploitation and child labor. An all solid state battery is suggested as a possible alternative battery that reduces operation risks and maintains similar performance characteristics. Lithium-lanthanum-zirconium oxide is presented as a suitable electrolyte replacement. Coupled with cobalt-free electrodes, this battery design would provide a safer, more responsible battery.
by Erick Ivan Hernandez Alvarez.
S.B.
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Yada, Chihiro. "Studies on electrode/solid electrolyte interface of all-solid-state rechargeable lithium batteries." 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/144024.
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Kyoto University (京都大学)0048
新制・課程博士
博士(工学)
甲第12338号
工博第2667号
新制||工||1377(附属図書館)
24174
UT51-2006-J330
京都大学大学院工学研究科物質エネルギー化学専攻
(主査)教授 小久見 善八, 教授 江口 浩一, 教授 田中 功
学位規則第4条第1項該当
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Howell, Ian. "The structure of some simple aqueous electrolyte solutions." Thesis, University of Bristol, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386083.
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Shao, Yunfan. "Highly electrochemical stable quaternary solid polymer electrolyte for all-solid-state lithium metal batteries." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1522332577785545.
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Li, Si. "HIGHLY CONDUCTIVE SOLID POLYMER ELECTROLYTE CONTAINING LiBOB AT ROOM TEMPERATURE FOR ALL SOLID STATE BATTERY." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1490481514905008.
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Chen, Kezheng. "Origin of Polarization Behavior in All-Solid-State Lithium-Ion Battery Using Sulfide Solid Electrolyte." Kyoto University, 2018. http://hdl.handle.net/2433/235998.
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Yin, Yijing. "An Experimental Study on PEO Polymer Electrolyte Based All-Solid-State Supercapacitor." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/440.
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Supercapacitors are one of the most important electrochemical energy storage and conversion devices, however low ionic conductivity of solid state polymer electrolytes and the poor accessibility of the ions to the active sites in the porous electrode will cause low performance for all-solid-state supercapacitors and will limit their application. The objective of the dissertation is to improve the performance of all-solid-state supercapactor by improving electrolyte conductivity and solving accessibility problem of the ions to the active sites. The low ionic conductivity (10-8 S/cm) of poly(ethylene oxide) (PEO) limits its application as an electrolyte. Since PEO is a semicrystal polymer and the ion conduction take place mainly in the amorphous regions of the PEO/Lithium salt complex, improvements in the percentage of amorphous phase in PEO or increasing the charge carrier concentration and mobility could increase the ionic conductivity of PEO electrolyte. Hot pressing along with the additions of different lithium salts, inorganic fillers and plasticizers were applied to improve the ionic conductivity of PEO polymer electrolytes. Four electrode methods were used to evaluate the conductivity of PEO based polymer electrolytes. Results show that adding certain lithium salts, inorganic fillers, and plasticizers could improve the ionic conductivity of PEO electrolytes up 10-4 S/cm. Further hot pressing treatment could improve the ionic conductivity of PEO electrolytes up to 10-3 S/cm. The conductivity improvement after hot pressing treatment is elucidated as that the spherulite crystal phase is convert into the fringed micelle crystal phase or the amorphous phase of PEO electrolytes. PEO electrolytes were added into active carbon as a binder and an ion conductor, so as to provide electrodes with not only ion conduction, but also the accessibility of ion to the active sites of electrodes. The NaI/I2 mediator was added to improve the conductivity of PEO electrolyte and provide pseudocapacitance for all-solid-state supercapacitors. Impedance, cyclic voltammetry, and gavalnostatic charge/discharge measurements were conducted to evaluate the electrochemical performance of PEO polymer electrolytes based all-solid-state supercapacitors. Results demonstrate that the conductivity of PEO electrolyte could be improved to 0.1 S/cm with a mediator concentration of 50wt%. A high conductivity in the PEO electrolyte with mediator is an indication of a high electron exchange rate between the mediator and mediator. The high electron exchange rates at mediator carbon interface and between mediator and mediator are essential in order to obtain a high response rate and high power. This automatically solves the accessibility problem. With the addition of NaI/I2 mediator, the specific capacitance increased more than 30 folds, specific power increased almost 20 folds, and specific energy increased around 10 folds. Further addition of filler to the electrodes along with the mediator could double the specific capacitor and specific power of the all-solid-state supercapacitor. The stability of the corresponded supercapacitor is good within 2000 cycles.
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Zhao, Fangtong. "A SOLID-STATE COMPOSITE ELECTROLYTE FOR LITHIUM-ION BATTERIES WITH 3D-PRINTING FABRICATION." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1619814091802231.
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Sun, Bing. "Functional Polymer Electrolytes for Multidimensional All-Solid-State Lithium Batteries." Doctoral thesis, Uppsala universitet, Strukturkemi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-248084.
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Pressing demands for high power and high energy densities in novel electrical energy storage units have caused reconsiderations regarding both the choice of battery chemistry and design. Practical concerns originating in the conventional use of flammable liquid electrolytes have renewed the interests of using solvent-free polymer electrolytes (SPEs) as solid ionic conductors for safer batteries. In this thesis work, SPEs developed from two polymer host structures, polyethers and polycarbonates, have been investigated for all-solid-state Li- and Li-ion battery applications. In the first part, functional polyether-based polymer electrolytes, such as poly(propylene glycol) triamine based oligomer and poly(propylene oxide)-based acrylates, were investigated for 3D-microbattery applications. The amine end-groups were favorable for forming conformal electrolyte coatings onto 3D electrodes via self-assembly. In-situ polymerization methods such as UV-initiated and electro-initiated polymerization techniques also showed potential to deposit uniform and conformal polymer coatings with thicknesses down to nano-dimensions. Moreover, poly(trimethylene carbonate) (PTMC), an alternative to the commonly investigated polyether host materials, was synthesized for SPE applications and showed promising functionality as battery electrolyte. High-molecular-weight PTMC was first applied in LiFePO4-based batteries. By incorporating an oligomeric PTMC as an interfacial mediator, enhanced surface contacts at the electrode/SPE interfaces and obvious improvements in initial capacities were realized. In addition, room-temperature functionality of PTMC-based SPEs was explored through copolymerization of ε-caprolactone (CL) with TMC. Stable cycling performance at ambient temperatures was confirmed in P(TMC/CL)-based LiFePO4 half cells (e.g., around 80 and 150 mAh g-1 at 22 °C and 40 °C under C/20 rate, respectively). Through functionalization, hydroxyl-capped PTMC demonstrated good surface adhesion to metal oxides and was applied on non-planar electrodes. Ionic transport behavior in polycarbonate-SPEs was examined by both experimental and computational approaches. A coupling of Li ion transport with the polymer chain motions was demonstrated. The final part of this work has been focused on exploring the key characteristics of the electrode/SPE interfacial chemistry using PEO and PTMC host materials, respectively. X-ray photoelectron spectroscopy (XPS) was used to get insights on the compositions of the interphase layers in both graphite and LiFePO4 half cells.
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Yang, Run. "A Superionic Conductive Solid Polymer Electrolyte Based Solid Sodium Metal Batteries with Stable Cycling Performance at Room Temperature." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1619741453185762.
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Grenier, Antonin. "Development of solid-state Fluoride-ion Batteries : cell design, electrolyte characterization and electrochemical mechanisms." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066128/document.
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Les batteries tout-solides à ions fluorures reposent sur l'échange réversible d'ions F- entre un métal et un fluorure métallique au travers d'un électrolyte solide. Ces dispositifs électrochimiques peuvent théoriquement permettre l'obtention de fortes densités énergétiques, bien supérieures à celles des batteries conventionnelles Li-ion commerciales. En conséquence, les batteries à ions F- suscitent un fort engouement. Dans ce contexte, une partie de nos travaux ont portés sur le développement d'une cellule permettant d'évaluer leurs performances. De plus, les propriétés électrochimiques de l'électrolyte solide LaF3 dopé BaF2, La1-xBaxF3-x, ont fait l'objet d'une attention particulière. Finalement, les changements structuraux s'effectuant au sein des électrodes lors des cycles de charge/décharge ont été étudiés afin de mieux comprendre les mécanismes électrochimiques mis en jeuSolid-state fluoride-ion batteries rely on the reversible exchange of the F- ion between a metal and a metal fluoride through a solid electrolyte. These electrochemical devices can theoretically reach energy densities superior to conventional Li-ion commercial batteries. Consequently, fluoride-ion batteries can be seen as a new promising chemistry generating a growing interest. In this context, a part of our work has been dedicated to the development of a cell allowing the evaluation of their electrochemical performance. Moreover, particular attention was given to the electrochemical properties of the solid electrolyte, BaF2-doped LaF3, La1-xBaxF3-x. Finally, the structural changes taking place at the electrodes upon charge/discharge were studied in order to gain insight into the electrochemical mechanisms involved in these devices
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Dodd, Andrew J. "Solid state NMR investigation of a novel Li ion ceramic electrolyte : Li doped BPOâ‚„." Thesis, University of Kent, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269079.
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Goel, Ekta. "A lithium-ion test cell for characterization of electrode materials and solid electrolyte interphase." Master's thesis, Mississippi State : Mississippi State University, 2008. http://library.msstate.edu/etd/show.asp?etd=etd-03062008-081546.
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Su, Zhongyi. "Performance enhancement of all-solid-state batteries by optimizing the electrolyte through advanced microscopy and tomography techniques." Thesis, The University of Sydney, 2020. https://hdl.handle.net/2123/22112.
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NASICON-structured electrolytes of Li1+xAlxGe2−x(PO4)3, abbreviated as LAGP, are relatively stable in ambient air, also show good performance regarding Li+ conductivity (up to10-3 S·cm-1 at room temperature), thus are promising applications in ASSLIBs. To understand the ion transport mechanism of LAGP and the Al/Ge exchange system, a detailed study of SEM, Nano-SIMS, TEM and APT characterization applied for LGP and LAGP(X=0.1,0.3,0.5).It was confirmed that, by doping aluminum, the substitution: LiGe2(PO4)3 → Li1+xAlxGe2−x(PO4)3, can be accomplished. Al3+ ions partially substitute Ge4+ ions, introducing extra Li+ ions inside the grain. Moreover, an amorphous phase forms along the grain boundaries as LiAlPO4, which contributes to the increase of the density and the improvement of the lithium ion mobility along the grain boundary. Doping extra aluminum enhances the electrochemical performance of the lithium battery by providing more lithium ion channels both inside the grain and along the grain boundaries. We also proved the feasibility of applying atom probe tomography for the ceramic solid electrolyte to study their atomic scale chemical composition.
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Lee, Myongjai. "Ionic conductivity measurement in magnesium aluminate spinel and solid state galvanic cell with magnesium aluminate electrolyte." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3273742.
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LINGUA, GABRIELE. "Newly designed single-ion conducting polymer electrolytes enabling advanced Li-metal solid-state batteries." Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2969103.
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Cui, Yuantao [Verfasser], and H. J. [Akademischer Betreuer] Seifert. "Phosphate based ceramic as solid-state electrolyte for lithium ion batteries / Yuantao Cui ; Betreuer: H. J. Seifert." Karlsruhe : KIT-Bibliothek, 2018. http://d-nb.info/1170230482/34.
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Paulus, Marc Christoffer Verfasser], Josef [Akademischer Betreuer] Granwehr, and Bernhard [Akademischer Betreuer] [Blümich. "NMR-investigations on the lithium solid state electrolyte Li10GeP2S12 (LGPS) / Marc Christoffer Paulus ; Josef Granwehr, Bernhard Blümich." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/1216040818/34.
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Wiemhöfer, Hans-Dieter. "Lithium Ion Transport in Polymer Electrolyte Films for Solid State Batteries – An Overview on Concepts, Techniques and Results." Diffusion fundamentals 21 (2014) 7, S.1, 2014. https://ul.qucosa.de/id/qucosa%3A32399.
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Fu, Guopeng. "INVESTIGATION ON THE STRUCTURE-PROPERTY RELATIONSHIPS IN HIGHLY ION-CONDUCTIVE POLYMER ELECTROLYTE MEMBRANES FOR ALL-SOLID-STATE LITHIUM ION BATTERIES." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1508508844968127.
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Ray, Brian M. "A STUDY OF THE LITHIUM IONIC CONDUCTOR Li5La3Ta2O12: FROM SYNTHESIS THROUGH MATERIALS AND TRANSPORT CHARACTERIZATION." UKnowledge, 2014. http://uknowledge.uky.edu/physastron_etds/18.
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The ionic conductivity of the lithium ionic conductor, Li5La3Ta2O12, is studied in an attempt to better understand the intrinsic bulk ionic conductivity and extrinsic sample dependent contributions to the ionic conductivity, such as grain boundary effects and the electrode-electrolyte interface. To characterize the material, traditional AC impedance spectroscopy studies were performed as well novel in-situ nanoscale transport measurements. To perform the nanoscale measurements, higher quality samples were required and new synthesis techniques developed. The results of these new synthesis techniques was samples with higher densities, up to 96% of theoretical, and slightly higher room temperature ionic conductivity, 2x10^−5 S/cm. By combining the AC impedance spectroscopy results and in-situ nanoscale transport measurements from this study and prior reported results, as well as introducing models traditionally used to analyze supercapacitor systems, a new interpretation of the features seen in the AC impedance spectroscopy studies is presented. This new interpretation challenges the presence of Warburg Diffusion at low frequencies and the offers a new interpretation for the features that have been traditionally associated with grain boundary effects.
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He, Ruixuan. "Studies on Ionic Conductivity and Electrochemical Stability of Plasticized Photopolymerized Polymer Electrolyte Membranes for Solid State Lithium Ion Batteries." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1478969519588062.
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Rendon, Piedrahita Camilo. "Study of highly conductive, flexible polymer electrolyte membranes and their novel flexoelectric effect." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1541440496157425.
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Lee, Jeremy J. "Fabrication and Characterizations of LAGP/PEO Composite Electrolytes for All Solid-State Lithium-Ion Batteries." Wright State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=wright1527273235003087.
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Auvergniot, Jérémie. "Étude des mécanismes aux interfaces électrode/électrolyte d’accumulateurs « bulk tout-solide »." Thesis, Pau, 2017. http://www.theses.fr/2017PAUU3044/document.
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Les deux décennies écoulées ont connu le formidable essor de l'électronique portable qui a bouleversé notre société, essor rendu possible par l'invention des batteries Li-ion, qui fournissent une densité d'énergie élevée pour un poids et un volume réduits. Nous assistons aujourd'hui à une diversification des besoins en termes de stockage électrochimique de l'énergie, avec le développement de nouvelles applications (énergies renouvelables, transport) dont les contraintes ne sont pas les mêmes. Pour certaines applications, les exigences en termes de sécurité des personnes seront aussi importantes que celles en termes de densité d’énergie et de coût. Par ailleurs, la recherche se tourne de plus en plus vers les batteries Na-ion dont le coût de dépend pas du prix du lithium. En résumé, tel ou tel système de stockage électrochimique sera adapté à telle ou telle application.Le remplacement des électrolytes organiques liquides par des électrolytes solides inorganiques est une solution intéressante pour améliorer la sûreté des batteries, les conducteurs ioniques inorganiques étant non-inflammables, stables à haute température, et supposés plus stables chimiquement et électrochimiquement. L’emploi de ces matériaux dans des batteries « bulk tout-solide » s'accompagne néanmoins de problèmes interfaciaux limitant leurs performances, tels que la perte de contact entre particules aux interfaces, ou encore des problèmes de compatibilité chimique et électrochimique entre les matériaux. L’un des problèmes affectant ce type de batteries est l’interdiffusion d’espèces aux interfaces, accompagnée d'une augmentation d'impédance des batteries au cours du cyclage. Bien que des solutions aient déjà été proposées, comme le revêtement des particules de matière active par une couche de matériau moins réactif, il y a un manque de connaissance des espèces chimiques formées aux interfaces par réaction entre les matériaux, connaissance nécessaire afin d’améliorer les performances de tels systèmes. C'est là que se situait l'objectif de cette thèse: étudier les interactions se produisant aux interfaces électrode-électrolyte au sein de batteries «bulk tout-solide», et identifier les espèces chimiques formées. Le travail a été réalisé entre l’IPREM de Pau et le LRCS de l'Université d'Amiens. Deux électrolytes solides ont été étudiés: l’argyrodite Li6PS5Cl et le NaSICON Na3Zr2Si2PO12. Les matériaux été synthétisés, puis intégrés dans des batteries «bulk tout-solide». Les interfaces ont été caractérisées par spectroscopie photoélectronique à rayonnement X (XPS) et par spectroscopie d’électrons Auger (AES), deux techniques complémentaires, la première permettant l'identification et la quantification des espèces chimiques en extrême surface, la seconde permettant d’obtenir des informations sur leur répartition à l'échelle nanométrique.L’analyse de batteries «bulk tout-solide» basées sur l’électrolyte Na3Zr2Si2PO12 et utilisant le matériau actif Na3V2(PO4)3 a permis mettre en évidence des modifications micromorphologiques au cours du cyclage, accompagnées de phénomènes d’interdiffusion des éléments entre les particules. Les analyses AES conduites sur ce type de batteries nous ont permis de mieux décrire les phénomènes d’autodécharge.Les analyses conduites sur les batteries basées sur l’électrolyte Li6PS5Cl nous ont permis de montrer que cet électrolyte solide présente une bonne stabilité vis à vis du matériau d'électrode négative LTO. En revanche, il présente une réactivité interfaciale avec des matériaux d'électrode positive tels que LCO, NMC, LMO, LFP, ou LiV3O8. Cette réactivité se traduit par la formation d'espèces aux interfaces incluant LiCl, P2Sx , Li2Sn , S0 et des phosphates. En dépit des problèmes de réactivité interfaciale constatés, nous avons pu au cours de cette thèse mettre au point des batteries « tout-solide » basées sur l’électrolyte Li6PS5Cl présentant une bonne rétention de capacité sur 300 cycles lorsqu'elles sont cyclées entre 2,8 et 3,4VThe last two decades have shown a tremendous spreading of portable electronics, changing our society. This change was made possible by the invention of Li-ion batteries, which provide a high energy density for a low weight and volume. More recently the development of new applications, such as electric vehicles or renewable energies, has led to new needs in terms of electrochemical storage. For some applications, user safety will be as important as cost and energy density. On the other hand, research around Na-ion batteries focuses an increased interest, because they do not depend on lithium cost. Replacing organic liquid electrolytes with inorganic solid electrolytes is an interesting solution to improve the safety of batteries, because inorganic ionic conductors are nonflammable, stable at high temperature, and supposed to be chemically and electrochemically more stable. Using those materials in all-solid-state batteries has however several limiting factors, such as loss of contact between particle at the interfaces during cycling, and also chemical/electrochemical compatibility issues between materials. Another issue with this type of batteries is the interdiffusion of species at interfaces leading to an impedance increase during cycling. Several solutions exist to mitigate those issues, such coating the active material particles with a less reactive inorganic material. However there is a lack of knowledge on the species forming at those interfaces, knowledge which is needed to improve the performances of such systems. Studying those interfacial interactions and characterizing the species formed as those interfaces was the main topic of this Ph.D thesis.This work has been done in collaboration between two laboratories : IPREM (University of Pau - CNRS, France) and LRCS (University of Amiens - CNRS, France). Two solid electrolytes have been studied: the argyrodite Li6PS5Cl and the NaSICON Na3Zr2Si2PO12. Those materials have been synthetized, then integrated in bulk all-solid-state batteries and their interfaces were characterized by X-Ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). Those two techniques provide us very complementary information, the first allowing identification and quantification of surface species, the second one giving access to the spatial repartition of elements at a nanometric level.The analysis of bulk all-solid-state batteries based on the electrolyte Na3Zr2Si2PO12 using the active material Na3V2(PO4)3 showed micromorphologic changes during cycling, as well as interdiffusion phenomena between particles. AES analysis also allowed us to describe self-discharge issues.The study of Li6PS5Cl-based batteries highlighted that this solid electrolyte is stable towards the negative electrode active material LTO. It however has interfacial reactivity towards positive electrode active materials such as LCO, NMC, LMO, LFP and LiV3O8. This reactivity leads to the formation of several species such as LiCl, P2Sx , Li2Sn , S0 and phosphates at the interface with Li6PS5Cl. In spite of the encountered interfacial reactivity issues, we managed to build all-solid-state batteries based on Li6PS5Cl showing a good capacity retention over 300 cycles when cycled between 2.8 and 3.4V
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Castillo, Adriana. "Structure et mobilité ionique dans les matériaux d’électrolytes solides pour batteries tout-solide : cas du grenat Li7-3xAlxLa3Zr2O12 et des Nasicon Li1.15-2xMgxZr1.85Y0.15(PO4)3." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLX107/document.
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L’un des enjeux pour le développement des batteries tout-solide est d’augmenter la conductivité ionique des électrolytes solides. Le sujet de la thèse porte sur l’étude de deux types de matériaux d’électrolytes solides inorganiques cristallins: les Grenat Li7- 3xAlxLa3Zr2O12 (LLAZO) et les Nasicon Li1.15- 2xMgxZr1.85Y0.15(PO4)3 (LMZYPO). L’objectif de cette étude est de comprendre dans quelle mesure les propriétés conductrices des matériaux étudiés sont impactées par des modifications structurales générées soit par un procédé de traitement particulier, soit par une modification de la composition chimique, et ce grâce au croisement des données structurales acquises par diffraction des rayons X (DRX) et Résonance Magnétique Nucléaire (RMN) MAS avec des données de dynamique des ions déduites de mesures de RMN en température et de spectroscopie d’impédance électrochimique (SIE).Les poudres ont été synthétisées après optimisation des traitements thermiques par méthode solide-solide ou solgel. La densification des pastilles utilisées pour les mesures de conductivité ionique par SIE a été réalisée par la technique de frittage Spark Plasma Sintering (SPS).Dans le cas des grenats LLAZO, l’originalité de notre travail est d’avoir montré qu’un traitement de frittage par SPS, au-delà de la densification attendue des pastilles, engendre également des modifications structurales qui ont des conséquences directes sur la mobilité des ions lithium dans le matériau et par conséquent sur la conductivité ionique. Une augmentation franche de la dynamique microscopique des ions lithium après frittage par SPS a en effet été observée par des mesures en température de RMN de 7Li et le suivi des constantes de relaxation.La deuxième partie de l’étude constitue un travail exploratoire sur la substitution de Li+ par Mg2+ dans LMZYPO. Nous avons ainsi étudié les propriétés de conduction ionique de ces composés mixtes Li/Mg, en parallèle d’un examen minutieux des phases cristallines formées. Nous avons notamment montré que la présence de Mg2+ favorise la formation des phases β’ (P21/n) et β (Pbna) moins conductrices ce qui explique la diminution de la conductivité ionique avec le taux de substitution de Li+ par Mg2+ observée dans ces matériaux de type Nasicon.Nos travaux soulignent donc l’importance primordiale des effets de structure sur les propriétés de matériaux d’électrolytes solides de type céramiqueOne of the issues for the development of all-solid-state batteries is to increase the ionic conductivity of solid electrolytes. The thesis work focuses on two types of materials as crystalline inorganic solid electrolytes: a Garnet Li7-3xAlxLa3Zr2O12 (LLAZO) and a Nasicon Li1.15-2xMgxZr1.85Y0.15(PO4)3 (LMZYPO). The objective of this study is to understand to what extent the conduction properties of the studied materials are impacted by structural modifications generated either by a particular treatment process, or by a modification of the chemical composition. Structural data acquired by X-ray diffraction (XRD) and Magic Angle Spinning (MAS) Nuclear Magnetic Resonance (NMR) were then crossed with ions dynamics data deduced from NMR measurements at variable temperature and electrochemical impedance spectroscopy (EIS).The powders were synthesized after optimizing thermal treatments using solid-solid or sol-gel methods. Spark Plasma Sintering (SPS) technique was used for the densification of the pellets used for ionic conductivity measurements by EIS.In the case of garnets LLAZO, the originality of our work is to have shown that a SPS sintering treatment, beyond the expected pellets densification, also generates structural modifications having direct consequences on the lithium ions mobility in the material and therefore on the ionic conductivity. A clear increase of the lithium ions microscopic dynamics after SPS sintering was indeed observed by variable temperature 7Li NMR measurements and the monitoring of the relaxation times.The second part of the study provides an exploratory work on the substitution of Li+ by Mg2+ in LMZYPO. We studied the ionic conduction properties of these mixed Li/Mg compounds, in parallel with a fine examination of the crystalline phases formed. We have showed in particular that the presence of Mg2+ favors the formation of the less conductive β’ (P21/n) and β (Pbna) phases, which explains the decrease of the ionic conductivity with the substitution level of Li+ by Mg2+ observed in these Nasicon type materials.Our work therefore highlights the crucial importance of structural effects on the conduction properties of ceramic solid electrolyte materials
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Yang, Xiangwen, Zhixing Lin, Jingxu Zheng, Yingjuan Huang, Bin Chen, Yiyong Mai, and Xinliang Feng. "Facile template-free synthesis of vertically aligned polypyrrole nanosheets on nickel foams for flexible all-solid-state asymmetric supercapacitors." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-224947.
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This paper reports a novel and remarkably facile approach towards vertically aligned nanosheets on three-dimensional (3D) Ni foams. Conducting polypyrrole (PPy) sheets were grown on Ni foam through the volatilization of the environmentally friendly solvent from an ethanol–water solution of pyrrole (Py), followed by the polymerization of the coated Py in ammonium persulfate (APS) solution. The PPy-decorated Ni foams and commercial activated carbon (AC) modified Ni foams were employed as the two electrodes for the assembly of flexible all-solid-state asymmetric supercapacitors. The sheet-like structure of PPy and the macroporous feature of the Ni foam, which render large electrode–electrolyte interfaces, resulted in good capacitive performance of the supercapacitors. Moreover, a high energy density of ca. 14 Wh kg−1 and a high power density of 6.2 kW kg−1 were achieved for the all-solid-state asymmetric supercapacitors due to the wide cell voltage window.
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Yang, Xiangwen, Zhixing Lin, Jingxu Zheng, Yingjuan Huang, Bin Chen, Yiyong Mai, and Xinliang Feng. "Facile template-free synthesis of vertically aligned polypyrrole nanosheets on nickel foams for flexible all-solid-state asymmetric supercapacitors." Royal Society of Chemistry, 2016. https://tud.qucosa.de/id/qucosa%3A30332.
Full textAbstract:
This paper reports a novel and remarkably facile approach towards vertically aligned nanosheets on three-dimensional (3D) Ni foams. Conducting polypyrrole (PPy) sheets were grown on Ni foam through the volatilization of the environmentally friendly solvent from an ethanol–water solution of pyrrole (Py), followed by the polymerization of the coated Py in ammonium persulfate (APS) solution. The PPy-decorated Ni foams and commercial activated carbon (AC) modified Ni foams were employed as the two electrodes for the assembly of flexible all-solid-state asymmetric supercapacitors. The sheet-like structure of PPy and the macroporous feature of the Ni foam, which render large electrode–electrolyte interfaces, resulted in good capacitive performance of the supercapacitors. Moreover, a high energy density of ca. 14 Wh kg−1 and a high power density of 6.2 kW kg−1 were achieved for the all-solid-state asymmetric supercapacitors due to the wide cell voltage window.
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Bu, Junfu. "Advanced BaZrO3-BaCeO3 Based Proton Conductors Used for Intermediate Temperature Solid Oxide Fuel Cells (ITSOFCs)." Doctoral thesis, KTH, Tillämpad processmetallurgi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-165073.
Full textAbstract:
In this thesis, the focus is on studying BaZrO3-BaCeO3 based proton conductors due to that they represent very promising proton conductors to be used for Intermediate Temperature Solid Oxide Fuel Cells (ITSOFCs). Here, dense BaZr0.5Ce0.3Y0.2O3-δ (BZCY532) ceramics were selected as the major studied materials. These ceramics were prepared by different sintering methods and doping strategies. Based on achieved results, the thesis work can simply be divided into the following parts: 1) An improved synthesis method, which included a water-based milling procedure followed by a freeze-drying post-processing, was presented. A lowered calcination and sintering temperature for a Hf0.7Y0.3O2-δ (YSH) compound was achieved. The value of the relative density in this work was higher than previously reported data. It is also concluded that this improved method can be used for mass-production of ceramics. 2) As the solid-state reactive sintering (SSRS) represent a cost-effective sintering method, the sintering behaviors of proton conductors BaZrxCe0.8-xLn0.2O3-δ (x = 0.8, 0.5, 0.1; Ln = Y, Sm, Gd, Dy) during the SSRS process were investigated. According to the obtained results, it was found that the sintering temperature will decrease, when the Ce content increases from 0 (BZCLn802) to 0.3 (BZCLn532) and 0.7 (BZCLn172). Moreover, the radii of the dopant ions similar to the radii of Zr4+ or Ce4+ ions show a better sinterability. This means that it is possible to obtain dense ceramics at a lower temperature. Moreover, the conductivities of dense BZCLn532 ceramics were determined. The conductivity data indicate that dense BZCY532 ceramics are good candidates as either oxygen ion conductors or proton conductors used for ITSOFCs. 3) The effect of NiO on the sintering behaviors, morphologies and conductivities of BZCY532 based electrolytes were systematically investigated. According to the achieved results, it can be concluded that the dense BZCY532B ceramics (NiO was added during ball-milling before a powder mixture calcination) show an enhanced oxygen and proton conductivity. Also, that BZCY532A (NiO was added after a powder mixture calcination) and BZCY532N (No NiO was added in the whole preparation procedures) showed lower values. In addition, dense BZCY532B and BZCY532N ceramics showed only small electronic conductivities, when the testing temperature was lower than 800 ℃. However, the BZCY532A ceramics revealed an obvious electronic conduction, when they were tested in the range of 600 ℃ to 800 ℃. Therefore, it is preferable to add the NiO powder during the BZCY532 powder preparation, which can lower the sintering temperature and also increase the conductivity. 4) Dense BZCY532 ceramics were successfully prepared by using the Spark Plasma Sintering (SPS) method at a temperature of 1350 ℃ with a holding time of 5 min. It was found that a lower sintering temperature (< 1400 ℃) and a very fast cooling rate (> 200 ℃/min) are two key parameters to prepare dense BZCY532 ceramics. These results confirm that the SPS technique represents a feasible and cost-effective sintering method to prepare dense Ce-containing BaZrO3-BaCeO3 based proton conductors. 5) Finally, a preliminary study for preparation of Ce0.8Sm0.2O2-δ (SDC) and BZCY532 basedcomposite electrolytes was carried out. The novel SDC-BZCY532 based composite electrolytes were prepared by using the powder mixing and co-sintering method. The sintering behaviors, morphologies and ionic conductivities of the composite electrolytes were investigated. The obtained results show that the composite electrolyte with a composition of 60SDC-40BZCY532 has the highest conductivity. In contrast, the composite electrolyte with a composition of 40SDC-60BZCY532 shows the lowest conductivity. In summary, the results show that BaZrO3-BaCeO3 based proton-conducting ceramic materials represent very promising materials for future ITSOFCs electrolyte applications.QC 20150423
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Takahashi, Masakuni. "Elucidation of the Dominant Factor in Electrochemical Materials Using Pair Distribution Function Analysis." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263748.
Full textAbstract:
京都大学新制・課程博士
博士(人間・環境学)
甲第23287号
人博第1002号
京都大学大学院人間・環境学研究科相関環境学専攻
(主査)教授 内本 喜晴, 教授 田部 勢津久, 准教授 戸﨑 充男
学位規則第4条第1項該当
Doctor of Human and Environmental Studies
Kyoto University
DFAM
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Castro, Alexandre. "Développement de batteries tout solide sodium ion à base d’électrolyte en verre de chalcogénures." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1S126/document.
Full textAbstract:
L'évolution des consommations énergétiques au cours des dernières décennies entraîne des modifications majeures dans la conception des systèmes électriques autonomes à fournir, que ce soit pour des applications électriques ou électroniques. La nécessité présente de réaliser des générateurs capables de délivrer l'énergie suffisante, avec une garantie de sûreté maximale, impose à la recherche l'exploration de nouvelles voies de stockage. Les voies actuelles par accumulateurs au lithium tendent à montrer leurs limites, tant stratégiques qu'environnementales. Dans ce cadre, la construction de nouveaux systèmes électrochimiques mettant en œuvre le sodium ouvre une possibilité de réalisation d'accumulateurs sans lithium. Le besoin de batteries toujours plus performantes oblige à des conceptions innovantes, abandonnant la voie liquide au profit de systèmes tout solide plus sécuritaires. De plus, la miniaturisation de l'électronique conduit à revoir le dimensionnement des batteries, vers des batteries de type micro, pour lesquelles l'intérêt d'un empilement tout solide n'est plus à démontrer. Aujourd'hui, des verres de chalcogénures au soufre permettent l'accès à des conductivités ioniques qui laissent entrevoir la possibilité d'une réalisation de batteries tout solide, à la fois sous forme de micro batteries ou de batteries massives. Un effort de recherche a été porté à la formulation de ces verres de chalcogénures afin d'obtenir des conductivités ioniques maximales et des propriétés autorisant leur utilisation comme électrolyte. La modification de ces verres met alors en lumière l'intérêt des différents éléments les composant. L'étude de la mise en forme de l'électrolyte par dépôts de type couches minces (obtenues par Radio Fréquence Magnétron Sputering, RFMS) prouve la faisabilité de ces micro batteries tout solide au sodium. Par la suite, la réalisation de batteries massives tout solide a demandé la synthèse de deux matériaux de cathode (NaCrO2 et Na[Ni0,25Fe0,5Mn0,25]O2) et de deux matériaux d'anode (Na15Sn4 et Na) permettant ainsi la mise en œuvre de quatre empilements électrochimiques, tous caractérisés comme accumulateurs. Enfin, l'amélioration des interfaces grâce à un gel-polymère a permis de perfectionner les propriétés des assemblages avec notamment une augmentation des vitesses de charge/décharge et une mobilisation accrue des matériaux actifs de cathodeThe evolution of energy consumption in recent decades has led to major changes in the design of autonomous electrical systems dedicated to either electrical or electronic applications. The present demand to build generators capable of delivering sufficient energy, with a guarantee of maximum safety, requires to explore new storage routes. The current lithium battery routes tend to show their limits, both strategic and environmental. In this context, the construction of new electrochemical systems implementing sodium opens the way of the lithium-free accumulators production. The need for ever more efficient batteries requires innovative designs, giving up the liquid path in favor of stronger solid systems. In addition, the miniaturization of electronics leads to a review of the size of the batteries, to micro-type batteries, for which the interest of a solid stack is no longer to demonstrate. Today, sulfur chalcogenide glasses allow access to ionic conductivities that suggest the possibility of a realization of all solid batteries, both in the form of micro batteries or massive batteries. A research effort has been made to formulate these chalcogenide glasses in order to obtain a maximum of ionic conductivity and properties allowing their use as electrolytes. The composition of these glasses highlights the interest of the different elements for such properties. The study of the electrolyte shaping by thin-film deposition (obtained by Radio Frequency Magnetron Sputering, RFMS) proves the feasibility of these all-solid sodium micro-batteries. Subsequently, the realization of massive all solid batteries required the synthesis of two cathode materials (NaCrO2 and Na [Ni0.25Fe0.5Mn0.25]O2) and two anode materials (Na15Sn4 and Na) thus allowing the implementation of four electrochemical stacks, all characterized as accumulators. Finally, the improvement of the interfaces thanks to a gel-polymer made it possible to improve the properties of the assemblies with notably an increase of the speeds of charge / discharge and an enhanced mobilization of the cathode active materials
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Grothe, Dorian C. "Entwicklung und Synthese von Materialien für Polyelektrolytmembranen mit ionischen Flüssigkeiten zum Einsatz in Lithium-Ionen-Batterien." Phd thesis, Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2013/6369/.
Full textAbstract:
Für den Einsatz in Autobatterien gibt es besondere Anforderungen an den Elektrolyten im Bereich der Energie- und Leistungsdichten, um beispielsweise thermische Verluste gering zu halten. Hochleitfähige Elektrolyte mit Leitfähigkeiten im Millisiemensbereich sind hier ebenso notwendig wie auch sichere, d.h. möglichst nicht brennbare und einen niedrigen Dampfdruck besitzende Materialien.
Um diese Vorgaben zu erreichen, ist es notwendig, einen polymeren Separator zu entwickeln, welcher auf brennbare organische Lösungsmittel verzichtet und damit eine drastische Steigerung der Sicherheit gewährleistet. Gleichzeitig müssen hierbei die Leistungsvorgaben bezüglich der Leitfähigkeit erfüllt werden.
Zu diesem Zweck wurde ein Konzept basierend auf der Kombination von einer polymeren sauerstoffreichen Matrix und einer ionischen Flüssigkeit entwickelt und verifiziert. Dabei wurden folgende Erkenntnisse gewonnen:
1. Es wurden neuartige diacrylierte sauerstoffreiche Matrixkomponenten mit vielen Carbonylfunktionen, für eine gute Lithiumleitfähigkeit, synthetisiert.
2. Es wurden mehrere neue ionische Flüssigkeiten sowohl auf Imidazolbasis als auch auf Ammoniumbasis synthetisiert und charakterisiert.
3. Die Einflüsse der Kationenstruktur und der Einfluss der Gegenionen im Bezug auf Schmelzpunkte und Leitfähigkeiten wurden untersucht.
4. Aus den entwickelten Materialien wurden Blendsysteme hergestellt und mittels Impedanzspektrometrie untersucht: Leitfähigkeiten von 10-4S/cm bei Raumtemperatur sind realisierbar.
5. Die Blendsysteme wurden auf ihre thermische Stabilität hin untersucht: Stabilitäten bis 250°C sind erreichbar. Dabei wird keine kristalline Struktur beobachtet.Within the field of energy storage and charge transfer, the lithium polymer batteries are one of the leading technologies, due to their low manufacture cost and their possible variety of packaging shapes. Despite their good thermal stability and very good weight to energy ratio, lithium ion batteries use as a electrolyte system a mixture of ethylene carbonate and diethyl carbonate as solvent which have a high risk of deflagration when they come in contact with water. Thus the developement of new materials for lithium-ion-batteries are necessary. For the electrolyte there are special requirements in terms of energy- and power density e.g. in order to minimize thermal loss. High conductivity electrolytes with conductivities in the range of milisiemens are as essential as safe materials, like non flammable non-volatile materials. To fulfill these requirements it is important to develop a polymeric lithium ion conductor, which is free of flammable organic solvents in order to ensure safety. Simultaneously it is also ,mandatory to achieve high performances in terms of ion-conductivity. Therefore a concept based on a combination of an oxygen rich polymeric matrix and ionic liquids was developed and verified. Following results were achieved . 1. Synthesis of new diacryalted oxygen rich matrix components with many carbonylfunctions for a good lithium ion transport. 2. Synthesis and characterization of new ionic liquids based on imidazol or ammonium compounds. 3. Investigation of the influences of the cation structure and counter ions for melting points and ion conductivity. 4. Creation of Blendsystems with the developed materials 5. Thermal investigations of these solid-state-electrolytes with DSC and TGA measurements, resulting in thermal stabilities up to 250°C.No crystallization were observed. 6. investigation of these solid-state-electrolytes via AC-impedance spectrometry, resulting in conductivities of 10-4S/cm at room temperature.
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Tarhouchi, Ilyas. "Etude des phases Li10MP2S12 (M=Sn, Si) comme électrolyte pour batteries tout-solide massives." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0220/document.
Full textAbstract:
En remplaçant l’électrolyte liquide par un solide, les batteries tout-solide massivessont souvent considérées comme une solution aux problèmes de sécurité desbatteries Li-ion actuelles. La récente découverte du matériau Li10GeP2S12 destructure dite LGPS présentant une conductivité ionique équivalente à celles desélectrolytes liquides a réactivé ce domaine de recherche.Dans cette optique, nous avons étudié les matériaux Li10MP2S12 (M=Sn, Si) destructure LGPS, au moyen de diverses caractérisations structurales (DRX,RMN du 31P, spectroscopie Mössbauer …), de propriétés de mobilité/conductionionique (RMN du 7Li, spectroscopie d’impédance) et de propriétés électrochimiques(voltammétrie cyclique, cyclage galvanostatique).Les échantillons commerciaux de Li10SnP2S12 contiennent des impuretés et uneincertitude subsiste sur la composition de la phase de structure LGPS. Lamodélisation des déplacements de RMN du 31P a notamment permis de mettre enévidence l’influence des lithium en site octaédrique adjacents. Les mesuresd’impédance suggèrent une réactivité avec le Li métallique et la voltammétrieconfirme que cette phase est très instable à bas potentiel, excluant son utilisation entant que simple électrolyte dans une batterie tout-solide. Nous proposons qu’il puisseêtre utilisé à la fois comme électrolyte et comme matériau de négative.L’étude préliminaire des matériaux au silicium souligne la difficulté d’obtention dematériau pur de structure LGPS, et conduit à la mise en cause du modèle structuraldit thio-LiSICON. Par ailleurs, elle montre là encore l’instabilité de ces matériauxface au lithium métalBy replacing the liquid electrolyte by a solid one, solid state batteries are oftenconsidered as a solution to safety issues in current Li-ion batteries. The recentdiscovery of Li10GeP2S12 with so-called LGPS structure, which exhibits an ionicconductivity equivalent to that of liquid electrolytes, has boosted related researchactivities.In this perspective, we studied the Li10MP2S12 (M=Sn, Si) materials with LGPSstructure, using various methods to characterize the structure (XRD, 31P NMR,Mössbauer spectroscopy …), the ionic mobility/conductivity (7Li NMR, Impedancespectroscopy), and the electrochemical properties (cycling voltammetry,galvanostatic cycling) of the material.Commercially available Li10SnP2S12 batches contain impurities and there remains anambiguity in the actual composition of the LGPS type phase. Modelling of the 31PNMR shifts reveals the effect of lithium in neighboring octahedral sites. Impedencemeasurements suggest reactivity with Li metal, and cyclic voltammetry confirms thatthe material is highly unstable at low potential, which excludes its use as a simpleelectrolyte in solid state batteries. We propose that it might be used both as anelectrolyte and as a negative electrode.The preliminary study on silicon based materials highlights difficulties in obtaining apure LGPS-type compound and questions the real nature of the so-calledthio-LiSICON structural model. Besides, it also shows the instability of thesematerials versus lithium metal
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aoxiang, Xiaoxiang. "Development of new proton conducting materials for intermediate temperature fuel cells." Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/887.
Full textAbstract:
The work in this thesis mainly focuses on the preparation and characterization of several phosphates and solid oxide systems with the aim of developing new proton conducting materials for intermediate temperature fuel cells (ITFCs). Soft chemical methods such as sol-gel methods and conventional solid state methods were applied for the synthesis of these materials. Aluminum phosphate obtained by a solution method is single phase and belongs to one of the Al(H₂PO₄)₃ allotropies with hexagonal symmetry. The material is stable up to 200°C and decomposes into Al(PO₃)₃ at a higher temperature. The electrical conductivity of pure Al(H₂PO₄)₃ is on the order of 10⁻⁶-10⁻⁷ S/cm, very close to the value for the known proton conductors AlH₃(PO₄)₂•3H₂O and AlH₂P₃O₁₀•2H₂O. Much higher conductivity is observed for samples containing even a trace amount of excess H₃PO₄. It is likely that the conduction path gradually changes from grain interior to the surface as the acid content increases. The conductivity of Al(H₂PO₄)₃-0.5H₃PO₄ exhibited a good stability over the measured 110 hours. Although tin pyrophosphate (SnP₂O₇) has been reported to show a significantly high conductivity (~10⁻² S/cm) at 250°C in various atmospheres, we observed large discrepancies in the electrical properties of SnP₂O₇ prepared by different methods. Using an excess amount of phosphorous in the synthetic procedure generally produces SnP₂O₇ with much higher conductivity (several orders of magnitude higher) than samples with stoichiometric Sn:P ratios in their synthetic procedure. Solid state ³¹P NMR confirmed the presence of residual phosphoric acid for samples with excess starting phosphorous. Transmission Electron Microscope (TEM) confirmed an amorphous layer covered the SnP₂O₇ granules which was probably phosphoric acid or condensed phases. Thereby, it is quite likely that the high conductivity of SnP₂O₇ results mainly from the contribution of the residual acid. The conductivity of these samples exhibited a good stability over the measured 80 hours. Based on the observations for SnP₂O₇, we developed a nano core-shell structure based on BPO₄ and P₂O₅ synthesised by solid state methods. The particle size of BPO₄ using this method varied between 10-20 nm depending on the content of P₂O₅. TEM confirmed the existence of an amorphous layer that is homogeneously distributed. The composite exhibits the highest conductivity of 8.8×10⁻² S/cm at 300°C in air for 20% extra P₂O₅ and demonstrates a good stability during the whole measured 110 hours. Polytetrafluoroethylene (PTFE) was introduced into the composites in order to increase malleability for fabrication. The conductivity and mechanical strength were optimized by adjusting the PTFE and P₂O₅ content. These organic-inorganic composites demonstrate much better stability at elevated temperature (250°C) over conventional SiC-H₃PO₄-PTFE composites which are common electrolytes for phosphoric acid fuel cells (PAFCs). Fuel cells based on BPO₄-H₃PO₄-PTFE composite as the electrolyte were investigated using pure H₂ and methanol as fuels. A maximum power density of 320 mW/cm² at a voltage of 0.31 V and a maximum current density of 1.9 A/cm² at 200°C were observed for H₂/O₂ fuel cells. A maximum power density of 40 mW/cm² and maximum current of 300 mA/cm² 275°C were observed when 3M methanol was used in the cell. Phosphoric acid was also introduced into materials with internal open structures such as phosphotungstic acid (H₃PW₁₂O₄₀) and heteropolyacid salt ((NH₄)₃PW₁₂O₄₀), for the purpose of acquiring additional connections. The hybrids obtained have a cubic symmetry with enlarged unit cell volume, probably due to the incorporation of phosphoric acid into the internal structures. Solid state ³¹P NMR performed on H₃PW₁₂O₄₀-xH₃PO₄ (x = 0-3) showed additional peaks at high acid content which could not assigned to phosphorus from the starting materials, suggesting a strong interaction between H₃PW₁₂O₄₀ and H₃PO₄. The conductivity of hybrids was improved significantly compared with samples without phosphoric acid. Fourier transform infrared spectra (FT-IR) suggest the existence of large amount of hydrogen bonds (OH••••O) that may responsible for the high conductivity. A H₂/O₂ fuel cell based on H₃PW₁₂O₄₀-H₃PO₄-PTFE exhibited a peak power density of 2.7 mW/cm² at 0.3 V in ambient temperature. Solid oxide proton conductors based on yttrium doped BaZrO₃ were investigated by introducing potassium or lanthanum at the A-sites. The materials were prepared by different methods and were obtained as a single phase with space group Pm-3m (221). The unit cell of these samples is slightly smaller than the undoped one. The upper limit of solid solution formation on the A-sites for potassium is between 5 ~ 10% as introducing more K results in the occurrence of a second phase or impurities such as YSZ (yttrium stabilized zirconium). K doped Barium zirconates showed an improved water uptake capability even with 5% K doping, whereas for La doped ones, water uptake is strongly dependent on particle size and synthetic history. The conductivity of K doped BaZrO₃ was improved by a factor of two (2×10⁻³ S/cm) at 600°C compared with undoped material. Fuel cells based on Pt/Ba₀₋₉₅K₀₋₀₅Zr₀₋₈₅Y₀₋₁₁Zn₀₋₀₄O[subscript(3-δ)]/Pt under humidified 5% H₂/air conditions gave a maximum power density 7.7 mWcm⁻² at 718°C and an interfacial resistance 4 Ωcm⁻². While for La doped samples, the conductivity was comparable with undoped ones; the benefits of introducing lanthanum at A-sites may not be so obvious as deficiency of barium is one factor that leads to the diminishing conductivity.
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Schmidt, Marek Wojciech, and Marek Schmidt@rl ac uk. "Phase formation and structural transformation of strontium ferrite SrFeOx." The Australian National University. Research School of Physical Sciences and Engineering, 2001. http://thesis.anu.edu.au./public/adt-ANU20020708.190055.
Full textAbstract:
Non-stoichiometric strontium iron oxide is described by an abbreviated formula SrFeOx (2.5 ≤ x ≤ 3.0) exhibits a variety of interesting physical and chemical properties over a broad range of temperatures and in different
gaseous environments. The oxide contains a mixture of iron in the trivalent and the rare tetravalent state. The material at elevated temperature is a mixed oxygen conductor and it, or its derivatives,can have practical
applications in oxygen conducting devices such as pressure driven oxygen
generators, partial oxidation reactors in electrodes for solid oxide fuel cells
(SOFC).
¶
This thesis examines the behaviour of the material at ambient and elevated temperatures using a broad spectrum of solid state experimental
techniques such as: x-ray and neutron powder diffraction,thermogravimetric and calorimetric methods,scanning electron microscopy and Mossbauer
spectroscopy. Changes in the oxide were induced using conventional thermal
treatment in various atmospheres as well as mechanical energy (ball milling).
The first experimental chapter examines the formation of the ferrite from
a mixture of reactants.It describes the chemical reactions and phase transitions that lead to the formation of the oxide. Ball milling of the reactants prior to annealing was found to eliminate transient phases from the reaction route and to increase the kinetics of
the reaction at lower temperatures.
Examination of the thermodynamics of iron oxide (hematite) used for the
reactions led to a new route of synthesis of the ferrite frommagnetite and
strontium carbonate.This chapter also explores the possibility of synthesis
of the material at room temperature using ball milling.
¶
The ferrite strongly interacts with the gas phase so its behaviour was studied under different pressures of oxygen and in carbon dioxide.The changes in ferrite composition have an equilibrium character and depend on temperature and oxygen concentration in the
atmosphere. Variations of the oxygen
content x were described as a function of temperature and oxygen partial
pressure, the results were used to plot an equilibrium composition diagram.
The heat of oxidation was also measured as a function of temperature and oxygen partial pressure.
¶
Interaction of the ferrite with carbon dioxide below a critical temperature
causes decomposition of the material to strontium carbonate and SrFe12O19 .
The critical temperature depends on the partial pressure of CO2 and above
the critical temperature the carbonate and SrFe12O19 are converted back into
the ferrite.The resulting SrFe12O19 is very resistant towards carbonation and
the thermal carbonation reaction does not lead to a complete decomposition
of SrFeOx to hematite and strontium carbonate.
¶
The thermally induced oxidation and carbonation reactions cease at room
temperature due to sluggish kinetics however,they can be carried out at ambient temperature using ball milling.The reaction routes for these processes are different from the thermal routes.The mechanical oxidation induces two
or more concurrent reactions which lead to samples containing two or more
phases. The mechanical carbonation on the other hand produces an unknown
metastable iron carbonate and leads a complete decomposition of the ferrite
to strontiumcarbonate and hematite.
¶
Thermally and mechanically oxidized samples were studied using Mossbauer
spectroscopy. The author proposes a new interpretation of the Sr4Fe4O11
(x=2.75) and Sr8Fe8O23 (x=2.875)spectra.The interpretation is based
on the chemistry of the compounds and provides a simpler explanation of
the observed absorption lines.The Mossbauer results froma range of compositions
revealed the roomtemperature phase behaviour of the ferrite also
examined using x-ray diffraction.
¶
The high-temperature crystal structure of the ferrite was examined using
neutron powder diffraction.The measurements were done at temperatures
up to 1273K in argon and air atmospheres.The former atmosphere protects
Sr2Fe2O5 (x=2.5) against oxidation and the measurements in air allowed
variation of the composition of the oxide in the range 2.56 ≤ x ≤ 2.81.
Sr2Fe2O5 is an antiferromagnet and undergoes phase transitions to the paramagnetic
state at 692K and from the orthorhombic to the cubic structure
around 1140K.The oxidized formof the ferrite also undergoes a transition
to the high-temperature cubic form.The author proposes a new structural
model for the cubic phase based on a unit cell with the Fm3c symmetry.
The new model allows a description of the high-temperature cubic form of
the ferrite as a solid solution of the composition end members.The results
were used to draw a phase diagramfor the SrFeOx system.
¶
The last chapter summarizes the findings and suggests directions for further research.
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Cozic, Solenn. "Étude des propriétés électriques et structurales de verres de sulfures au lithium pour électrolytes de batteries tout-solide." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S054/document.
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Le marché du stockage de l'énergie est en perpétuelle expansion, tant pour les applications nomades que fixes. Afin de répondre aux exigences requises pour les diverses applications (appareils électroniques, véhicules hybrides et électriques, stockage des énergies renouvelables…), des batteries toujours plus performantes, compactes et légères doivent être développées. Pour cela, les batteries utilisant du lithium métallique en tant qu'anode sont les plus attractives en termes de densités d'énergies. Néanmoins, l'utilisation d'électrolytes liquides conventionnels, généralement des solvants organiques inflammables, dans de tels dispositifs soulève des problématiques de sécurité. Les travaux de recherche présentés dans ce manuscrit concernent l'étude de matériaux vitreux pouvant être utilisés en tant qu'électrolyte solide afin de permettre le développement de batteries tout-solide sûres et performantes. Des verres de sulfures au lithium, attractifs pour leurs propriétés de conduction ionique, sont étudiés et caractérisés. Les propriétés de conduction ionique dans les verres étant toujours mal comprises et sujettes à controverses, l'analyse structurale des verres présente ici un réel intérêt pour une meilleure compréhension des corrélations entre structure et propriétés. Un effort de recherche a donc été porté sur l'étude de l'ordre local dans les verres préparés via différentes techniques d'analyse structurale complémentaires. Enfin, les matériaux vitreux, sont de manière générale relativement faciles à mettre en forme. Les verres étudiés dans ce manuscrit peuvent alors également être utilisés en tant qu'électrolytes sous forme de couches minces dans les micro-batteries. Des premiers essais de dépôts par pulvérisation cathodique RF magnétron de couches minces conductrices ont donc été effectués et constituent la première brique à la fabrication de micro-batteriesThe energy storage market is in constant growth for both portable and stationary applications. To satisfy the requirements of various applications (electronic devices, hybrid-electric vehicles, renewable energy storage…), always more efficient, more compact and lightweight batteries have to be developed. Then, thanks to their high energy densities, batteries using Li metal anodes are the most promising to complete this challenge. However, the use of conventional liquid electrolytes raises safety issues, mainly related to the flammability of the organic liquid. In this thesis, glassy materials, exhibiting great interest towards developing solid electrolytes are considered and might enable the development of safe and efficient all-solid-state batteries. Here, Li-sulfide glasses, attractive for their ionic conduction properties, have been studied and characterized. The ionic conduction properties of glasses are still misunderstood and controversial, the structural investigation of glasses is of great interest in order to get a better understanding of structure-properties relationship. Then, the short and intermediate range order of prepared glasses have been investigated by the mean of various complementary structural analysis techniques. Finally, glassy materials are usually quite easy to shape. Thus, studied glasses in this thesis can also be used as thin-film electrolytes in microbatteries. First tests of sputtering of conducting thin-films have been performed by RF magnetron sputtering and constitute a first step in order to design microbatteries
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Biswas, Tanujit. "Investigation of Switching mechanism, Thermal, Electrochemical and Structural properties of Solid Electrolytic, Superionic α-AgI based Silver Molybdate glass for Resistive Memory (RRAM) Applications." Thesis, 2019. https://etd.iisc.ac.in/handle/2005/4346.
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Developing efficient, fast performing and thermally stable AgI-Ag2O-MoO3glasses are of great interest for Resistive Random Access Memory (RRAM) applications; however there many challenges such as metallization in bulk, behavior of Vth profile over composition and corrosion reactions. In this thesis work, fast ion conducting (FIC) AgI-Ag2O-MoO3 glasses have been investigated with an idea to solve some technical challenges such as thermal stability, corrosion etc. with the help of deep understanding of the material. Employing various experimental and characterization techniques, this research work aims to identify the links between various material and technical aspects and how to tune these aspects to solve the challenges envisaged.
Bulk AgI-Ag2O-MoO3 (50:25:25) glasses have been prepared by melt quenching method (Microwave heating and quenched between two heavy steel plates). The electrical switching experiments have been carried out using a Keithley Source Meter (model 2410) controlled by Lab VIEW 6i, on samples of thicknesses (d) 0.1, 0.2 and 0.3 mm at different ON state currents (Imax) (3 mA, 2 mA, 1 mA, 0.6 mA, 0.4 mA and 0.25 mA); It has been found that these samples exhibit fast near ideal memory switching. The power dissipation (P) increases with both d and Imax. It is also found that the threshold voltage (Vth) increases with d; and for a given thickness, the Vth decreases with increasing Imax. A sample of d = 0.1 mm exhibits near ideal memory switching with the least P for Imax = 0.25 mA. These samples can be used for fast switching applications with minimum power dissipation. Further, the electrical switching behavior of bulk, FIC (AgI)50+x-(Ag2O)25-(MoO3)25-x, for 10 ≤ x ≤ -10 glasses has been investigated, in order to understand the switching mechanism of bulk samples with the inert electrodes. It is found that by using inert electrodes, the switching becomes irreversible, memory type. In these samples, the switching mechanism is an electrochemical metallization process. The inert electrodes restrain ionic mass transfer; however exhibit a low barrier to electron transfer allowing the cathodic metallization reaction to reach Nernst equilibrium faster. The cations involved in this process transport thorough the free volume within the glass structure and follows Mott-Gurney (MG) model for electric field driven thermally activated ion hopping conductivity. This model along with the thermal stability profile provide a narrow region within composition with better switching performance based on swiftness to reach Vth and less power loss. It is found that traces of anionic contribution to metallization are absent. Moreover, anodic oxidation involves reactions that cause bubble formation and corrosion which becomes evident from SEM (Scanning electron Microscope) micrographs of the switched and un-switched parts of the sample.
Rigidity percolation phenomena in (AgI)50+x-(Ag2O)25-(MoO3)25-x, for 5 ≤ x ≤ -12.5 has been observed by performing calorimetry (ADSC) and photoelectron spectroscopy experiments (XPS). The temperature dependence of heat capacity (normalized Cp) at glass transition temperature (Tg), exhibits fluctuations for samples with higher AgI concentration indicating the fragile nature of the glass. The composition range chosen in the present study, accommodates both the fragile and strong glasses, and the fragility threshold. Cp (absolute) values, at Tg, exhibits abrupt sign shift at this threshold. The negative Cp is identified as a thermodynamic behavior of nanoclusters. The XPS study shows the formation of covalent structural units, [‒Mo‒O‒Ag‒O‒] and complex molybdenum oxides in the positive Cp region. Finally, the non-reversing enthalpy profile, exhibits square well minima, sandwiched between floppy and stress rigid region, which has been identified to be the intermediate phase, within the range 32.25 ≤ MoO3 concentration ≤ 35.
Electrochemical Impedance Spectroscopy (EIS) and Raman studies have been performed on this glass, over a wide range of composition ((AgI)50+x-(Ag2O)25-(MoO3)25-x, for 3.75 ≤ x ≤ -10.5) to understand the features of structure, ion migration and their correlation. These features essentially involve diffusion and relaxation. The coefficients associated with diffusion process, especially, the diffusion coefficient, diffusion length and relaxation time has been determined by applying Nguyen-Breitkopf method. Besides, by tuning the concentration of the constituents, it is possible to obtain samples which exhibit two important structural characteristics, namely fragility and polymeric phase formation. The present study essentially addresses these issues and endeavors to figure out the corroboration among them. The relaxation behavior, when scrutinized in the light of Diffusion Controlled Relaxation (DCR) model, ascertains the fragility threshold which is also identified as the margin between the two types of polymeric phases. Simultaneously, it fathoms into the equivalent circuitry, its elements and their behavioral changes with above mentioned features. The power law behavior of A.C. conductivity exhibits three different non-Jonscher type dispersive regimes along with a high frequency plateau. The sub-linearity and super-linearity remain significantly below and above the Jonscher’s carrier transport limit, 0.5 ≤ n ≤ 0.9. Finally, by observing the behavior of the crossover between these sun-linear and super-linear (SLPL) regime, an intuitive suggestion has been proposed for the appearance of SLPL: oxygen vacancy formation.
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Lee, Andrew Campbell Mitchell Reginald Bowman Craig T. Gür Turgut M. "Analysis of solid state, solid oxide electrolyte based direct carbon fuel cells." 2010. http://purl.stanford.edu/jy917qh3163.
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Li, Shu-Tuan, and 李淑端. "Preparation of All-Solid-State Polymeric Electrolyte Electrochromic Device." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/56834843526330927035.
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碩士逢甲大學
材料與製造工程所
91
Abstract The rapid development of electrochromic materials has draw much attention to the evaluation of the performance of its devices. To understand the dynamic performance is necessary for the sake of making a reliable electrochromic device in commercial purpose, which in term mostly is all-solid-state electrochromic devices. The key to the success of these products reflects strongly on various electrochromic performance of such a device. These include response time, memory effect, transmittance, optical density change and color-bleach cyclic lifetime. In this study, a thin electrochromic WO3 layer which is deposited by magnetron sputtering. The representation of organic-solid-state electrolyte electrochromic device was performed with different thickness of organic electrolyte layers at different working voltages. The cyclic V-I curve, response time and UV-Vis. transmittance during coloring and bleaching state were measured to understand the effect of electrochromic properties. The memory effect and cyclic lifetime of these devices were also estimated. The result of this study shows the electrochromic devices with thicker organic electrolyte layer response faster, A threashold voltage of ±1.5 V is needed to drive the device. The cyclic lifetime is about 40 cycles when operated at ±2.5 V. Electrochromic device has a good memory effect and the transmittance of colored and bleached state go to a steady state gradually after several cycles. Higher transmittance and higher optical density change is also obtained. Light transmittance of colored and bleached state of the device can be adjusted by working voltage. The change of light transmittance and optical density change give rise to a maximum value when operated at a higher working voltage of ±3.0 V, over which the device becomes damaged. Working voltage also affects the device cyclic lifetime. Key words：tungsten oxide、electrochromic、all-solid-state polymeric electrolyte
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Tseng, Jian-Wei, and 曾建瑋. "Preparation of Doped Ceria by Tape for Solid State Electrolyte." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/7ayh6r.
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碩士國立東華大學
材料科學與工程學系
95
The structure, microstructure, ionic conductivity and mechanical properties of 20mole% Ce0.8M0.2O1.9(M=La、Sm、Gd、Y)nanopowder, prepared by chemical coprecipitation were investigated. According to X-ray diffraction analysis, the diffraction peak cause shift depend on size of dopant radii. All of the dopant were solid solution in ceria with the cubic fluorite structure. The powders were pressed into pellets by uniaxially. All sample were sintered at 1500℃ for 5hr.The density of ceramices were over 90% of the theoretical density. The maximum ionic conductivity, σ800℃= 6.54 x 10-2S/cm with minimum activation energy, Ea=0.688eV was found for the Ce0.8Sm0.2O1.9 result in measure of ionic conductivity. The average grain size proportion to size of dopant radii. The maximum fracture toughness, KIC=6.73MPa.m1/2 was found for the Ce0.8La0.2O1.9 has the most large grain, it indicated could resists the mircocrack to pass. From the Zeta potential measure, we find the Poly(acrylic acid),PAA in the gadolinium doped-ceria(GDC) is 1wt%, the PAA in the samarium doped-ceria(SDC) is 2wt%, the PAA in the yttrium doped-ceria(YDC) is 2wt% and the PAA in the lanthanum doped-ceria(LDC) is 1.5wt%, respectively and well-dispersed ability between the particle. All have the pseudo-plastic fluid properties after to make slurries. The tape were sintered at 1500℃ for 5hr. The maximum viscosity value, η =4000~8500mPa.s was found for the Ce0.8La0.2O1.9 has poor densification, it exhibited bad dispersed of the slurry has great effect with regard to later sintering property.
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劉柏柔. "A Study for Solid State Electrolyte in the Lithium Ionic Batteries." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/16690946020948188138.
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碩士義守大學
材料科學與工程研究所
87
LiTi2 (PO4)3 with the NASICON-type crystal structure is one of the promissing Lithium-ion conductive solid electrolytes. Without any cation substitution, LiTi2(PO4)3 has been reported to have a very low ionic conductivity at room temperature. However, if Al+3 and Si+4 partially replace Ti+4 and P+5 into this Lithium-containing crystal structure, its ionic conductivity is significantly increased. The system (Li,R)1+x (Ti,M)2 (SixP3x)O12 (R=Mg,Ca,and rare earth metai; M=Al, and transition metal) was studied, Through substitution of different ions, the ionic conductivity of this Lithium-containing battery was systematically measured at various (-20℃
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Brandão, José Paulo Leal. "Study of Na2.99Ba0.005ClO solid-state electrolyte properties with temperature and radiation." Master's thesis, 2019. https://hdl.handle.net/10216/125678.
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Brandão, José Paulo Leal. "Study of Na2.99Ba0.005ClO solid-state electrolyte properties with temperature and radiation." Dissertação, 2019. https://hdl.handle.net/10216/125678.
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Raj, Vikalp. "Enabling Lithium Metal Anode for Garnet Electrolyte based Solid State Batteries." Thesis, 2022. https://etd.iisc.ac.in/handle/2005/5920.
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Solid-state lithium metal batteries (SSLMB) employing inorganic solid electrolytes (ISE) in conjunction with lithium metal anode and intercalation cathode are considered among the most promising alternatives for Li-ion batteries1. Li-metal is an optimal choice of anode because of its high gravimetric and volumetric energy density. ISE, along with being flame-retardant, has a superior tolerance for a wide operating temperature range (−30 to 100 °C) while delivering a reliable performance2. The high shear modulus of ISE is also expected to mechanically suppress lithium dendrite growth3, thus enabling high energy density batteries. However, lithium dendrite penetration at current densities as low as 50 µA/cm2 was observed in SSLMBs4, while current densities of ≥1mA/cm2 are desired for practical use. The microscopic mechanisms that lead to lithium dendrite growth in SSLMBs are still unclear. Furthermore, the poor electrode/electrolyte interface coupled with processing challenges of ISEs have thwarted their realization as a practical battery system5.
In the present work, we investigate dendrite growth through ISE, one of the most fundamental challenges with SSLMBs. First, for the choice of ISE, we synthesized Li6.4La3Zr1.4Ta0.4O12 (LLZTO), a garnet-type fast Li-ion conducting oxide. We interface lithium metal to this ISE via a well-known approach of employing a lithium alloying interlayer in between lithium metal and ISE. However, cells fabricated using aluminium interlayer show signs of dendrite growth at a current density of <300 µA/cm2. Through a set of electrochemical and scanning electron microscopy (SEM) techniques, we observed that interfacial voids at Li/LLZTO interface precede dendrite nucleation and growth. We believe that the edges of these voids can act as a favourable nucleation site for dendrites. Using a simple electrostatic model, we show that current density at the edges of the voids could be amplified by as much as four orders of magnitude, making the cells highly susceptible to dendrite growth after void formation. By employing standard pattering to induce controlled discontinuities, we further confirm our hypothesis by showing selective dendrite growth along the edges of discontinuities6.
Based on the above observations, we developed strategies to increase the tolerance for dendrite growth in these battery systems. We note that the aluminium interlayer will dissolve with lithium metal over time, making the interface susceptible to discontinuities, as observed in cells without interlayers. Hence, if a material that doesn’t alloy with lithium while also fulfilling the criteria of an interlayer is used, it can enhance the current densities for dendrite nucleation. Based on this, we employed tungsten (W) as an interlayer material. We observed that current densities for dendrite nucleation in W interlayer cells were ≥ 530 µA/cm2, nearly twice that of Al-interlayer cells. Computational calculations showed that lithium vacancy migration energies, which is the first step for void formation, were 2-5 times higher for W surface than for Al surface, further confirming our observation6.
Increasing the structural density of LLZTO ISE further improved the current density to 1 mA/cm2. Finally, we explored the anode-free battery configuration, which employs in-situ generated metallic lithium anode without a need for lithium handling, a significant processing advantage for wide-scale production of SSLMBs. Our work is an essential step in realizing a practical SSLMB whilst gaining mechanistic insights into dendrite growth in these energy storage systems.
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Chu, Chen-Te, and 祝陳德. "Investigation of β"-Al2O3 for Composite Solid Electrolyte and All-Solid-State Sodium Ion Batteries." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/cnpqrc.
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Liou, Jiann-Hwa, and 劉建華. "Research and Development of High-Temperature Solid-State Electrolyte Ceramic Fuel Cell." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/66068661988091697005.
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碩士義守大學
材料科學與工程學系
87
Bismuth-oxide-containing materials have been extensively studied because of their excellent ionic conductivity at high temperatures. For obtaining a wide temperature and composition range forδ- Bi2O3 , several oxides such as rare earth oxides and transition metal oxides are used to stabilize this phase at low temperatures. In this study, a hot-pressing technique is used to fabricate these materials at different temperatures. Several analytical methods such as XRD, DTA, SEM, Dilatometric, and LCR meter method are also used to determine the relationships among dopant’s composition, phase, microstructure, and ionic conductivity. The hot-pressing method is found to be a powerful fabrication method for fully densifying bismuth-oxide-containing materials at 700℃~830℃in a short period of time 30 min . The stabilization effect ofδ- Bi2O3 is closely related to dopant’s composition. Among these oxide dopants, Y2O3 and Nb2O5 have better stabilization effects for high-temperature cubic phases. Fractographs of sintered specimens change with the phase and phase content. With the monoclinic, cubic phase, or rhombohedral phase, the corresponding fractograph is layered, intergranular, or twin-related morphology respectivity. Furthermore, the correlations between the high-temperature phase and the phase in the quenched specimen are explained from DTA curves. In these Bi2O3-MxOy binary systems, dopants Y2O3 and Nb2O5 show excellent ionic conductivities at 700℃, which are 0.049 S㎝-1 for 25 mol% Y2O3 and 0.047 S㎝-1 for 12 mol% Nb2O5.
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Chang, Chein Ping, and 張建平. "The Preparation and Properties of Polymer Electrolyte for Solid State Lithium Battery." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/21279126983981855592.
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Lai, Y. J., and 賴永俊. "The study of electrochemical behavior of solid state electrolyte for lithium battery." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/62795773410382944774.
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碩士國立清華大學
材料科學工程學系
88
TiO6 octahedra and PO4 tetrahedra are linked by the corners oxygen atoms to form a Lithium titanium phosphate , LiTi2(PO4)3 , which is a 3D network with space group R3C . The are two different types of lithium ion sites exist in the LiTi2(PO4)3 , N(1) and N(2) . In this study , Al2O3 and Fe2O3 are introduced to LiTi2(PO4)3 structure to observe its effects to the conductivity and chemical stability . It is found that the ionic conductivity of Li1.3Al0.09Fe0.21Ti1.7(PO4)3 would approach to 10-3 S/cm because the porosities is decreased and the densification of the pellet sample . Besides, the chemical stability of this system is excellent. Conseqently, the Li1.3FeyAl0.3-yTi1.7(PO4)3 (y=0~0.3) is a good material for solid state electrolyte .
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Su, Shih-Hsuan, and 蘇世軒. "Fabrication and characterization of ionic SPEEK electrolyte for All-Solid-State supercapacitor." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/34523745941550383064.
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Liang, Yun-yuan, and 梁雲淵. "Synthesis of apatite-type lanthanum silicate as a solid oxide fuel cell electrolyte via solid state reaction." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/g8zr94.
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碩士國立臺灣科技大學
機械工程系
99
Lanthanum silicate structural with formula La10-x(SiO4)6O2+δ (LSO) are potential candidates for IT-SOFC and LT-SOFC because of its high ionic conductivity and low activation energy. Rather than fluorite and perovskite structure with high symmetric structure, lanthanum silicate with apatite-type structure is belong to hexagonal structure and believed to migrate via an interstitial conduction mechanism. Studies have indicated that LSO synthesized via solid state reactions have to be sintered at high temperature (＞1600 ℃) to achieve the desired densities. According to phase equilibrium diagram of La2O3/SiO2, the composition of La9.33(SiO4)6O2 is a intermediate phase , and La2SiO5 or La2Si2O7 are easily formed as secondary phases. In addition, it’s difficult to control the stoichiometry of LSO due to the hygroscopicity of its staring materials La2O3. In this study, apatite-type lanthanum silicates La10(SiO4)6O3 were prepared by solid state reaction using powders of La(OH)3 and SiO2 as starting materials. The calcined samples are characterized by XRD and the results indicate that LSO have been obtained after calcination at 1200 ℃, but the La2Si2O7 impurity is formed after sintered at 1550 and 1600 ℃. TGA of the LSO powders were performed under hydrogen atmosphere, and the results indicates that LSO is a stable SOFC electrolyte materials. The effect of microstructure on the conductivity was also investigated, and the results show that the sintered ceramic with coarse grain size exhibits higher conductivity than fine one at low temperature. In addition, the aging test of LSO indicates that the sintered ceramic with La2Si2O7 impurity maintains a conductive stability.