Dissertations / Theses on the topic 'LiBH4'
To see the other types of publications on this topic, follow the link: LiBH4.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 21 dissertations / theses for your research on the topic 'LiBH4.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Bösenberg, Ulrike Verfasser], and Rüdiger [Akademischer Betreuer] [Bormann. "LiBH4-MgH2 Composites for Hydrogen Storage : LiBH4-MgH2 Komposite für die Wasserstoffspeicherung / Ulrike Bösenberg ; Betreuer: Rüdiger Bormann." Hamburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2009. http://d-nb.info/1175884405/34.
Full text
2
Rivera, Luis A. "Destabilization and characterization of LiBH4/MgH2 complex hydride for hydrogen storage." [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0001984.
Full text
3
Morin, François. "Effet de la pression et de l'addition de fer sur la désorption du système LIBH4 + MgH2." Thèse, Université du Québec à Trois-Rivières, 2012. http://depot-e.uqtr.ca/4464/1/030300172.pdf.
Full text
4
Marizy, Adrien. "Super-hydrures sous pression pour le stockage de l’hydrogène et la supraconductivité : développement d’outils et résultats sur H3S, CrHx, LiBH4 et NaBHx." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX115/document.
Full textAbstract:
Récemment, sous des pressions de plusieurs gigapascals, de nouveaux hydrures ont été synthétisés avec des propriétés étonnantes potentiellement porteuses de ruptures technologiques pour le stockage de l’hydrogène ou la supraconductivité. Plusieurs superhydrures sont étudiés expérimentalement et simulés par DFT dans cette thèse. Les diagrammes de phases en pression de LiBH4 et NaBH4, deux composés d’intérêt pour le stockage de l’hydrogène, sont explorés par diffraction de rayons X, spectroscopie Raman et infrarouge jusqu’à des pressions de 300 GPa sans observer de décomposition. L’insertion d’hydrogène dans NaBH4 donne le super-hydrure NaBH4(H2)0.5. Pour éclaircir l’interprétation de la supraconductivité record à 200 K trouvée dans H2S sous pression, le super-hydrure H3S a été synthétisé à partir des éléments S et H. Les résultats de diffraction semblent en désaccord avec l’interprétation communément admise qu’H3S en phase Im-3m est responsable de cette supraconductivité et laisse la porte ouverte à d’autres interprétations. Enfin, les super-hydrures CrHx avec x=1, 1.5 et 2 ont également été synthétisés à partir des éléments et caractérisés par diffraction de rayons X. Si ces hydrures correspondent bien àceux qui avaient été prédits numériquement, l’absence des stoechiométries plus élevées est discutée. Pour mesurer les températures de supraconductivité calculées dans les superhydrures MHx, une cellule à enclumes de diamant miniature permettant une détection de l’effet Meissner a été développéeRecently, under pressures of several gigapascals, new hydrides have been synthesised with striking properties that may herald technological breakthroughs for hydrogen storage and superconductivity. In this PhD thesis, several superhydrides have been studied experimentally and simulated by DFT. The pressure phase diagrams of LiBH4 and NaBH4, two compounds of interest for hydrogen storage, have been explored thanks to X-ray diffraction and Raman and infrared spectroscopy up to pressures of 300 GPa without observing any decomposition. The insertion of hydrogen inside NaBH4 generates the superhydride NaBH4(H2)0.5. To refine the interpretation of the record superconductivity found in H2S under pressure at 200 K, the superhydride H3S has been synthesised from S and H elements. The results of the diffraction study seem to be at odds with the commonly accepted interpretation that Im-3m H3S is responsible for the superconductivity observed and leaves the door open to other interpretations. Finally, CrHx hydrides with x = 1, 1.5 and 2 have also been synthesised from the elements and characterised by X-ray diffraction. Although these hydrides do correspond to the ones that had been numerically predicted, the absence of the expected higher stoichiometries is discussed. To measure the superconductivity temperatures calculated for MHx hydrides, a miniature diamond anvil cell which allows the detection of a Meissner effect has been developed
5
GHAANI, MOHAMMAD REZA. "Study of new materials and their functionality for hydrogen storage and other energy applications." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2014. http://hdl.handle.net/10281/49808.
Full textAbstract:
The first part of this thesis deals with hydrogen storage materials, in view of their applications as promising energy carriers. One of the main open problems with these materials is: how can their decomposition temperature be lowered, when hydrogen is wanted to be released, so as to improve the energy efficiency of the process. A possible answer is given by joint decomposition of two or more hydrides, if very stable mixed compounds are formed (‘hydride destabilization’). Aiming at this result, the new hydride composite 2LiBH4-Mg2FeH6 was considered, it was synthesized, and its thermodynamic and kinetic properties were investigated.
In the second part of this thesis work lithium oxide materials, of relevant interest for applications to batteries, were investigated. The chemical lithiation reaction of niobium oxide was considered, as equivalent to the electrochemical process of lithium insertion on discharging a Nb2O5 cathode vs. a metal Li anode. Thus, the Li2Nb2O5 compound was synthesized by reaction of monoclinic a-Nb2O5 with n-butyllithium.This material was investigated by neutron powder diffraction (D2B equipment at ILL, France) and its structure was Rietveld refined in space group P2 to wRp=0.045, locating the Li atoms inserted in the a-Nb2O5 framework.
6
Šašek, Martin. "Charakterizace elektrolytů na bázi směsi iontová kapalina a aprotické rozpouštědlo." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-318870.
Full textAbstract:
The thesis deals with liquid aprotic electrolytes based on mixtures of ionic liquid and solvent. EmimBF4, namely 1-ethyl-3-ethylimidazolium tetrafluoroborate, was used as the starting ionic liquid. A mixture of propylene carbonate, ethylene carbonate and dimethyl carbonate was used as solvents. Electrolytes were enriched with two electrolyte salts LiBF4 and NaBF4 from the resulting mixtures selected the most suitable electrolytes for Li-ion and Na-ion accumulators. Electrolytes were selected taking into account the required properties: the width of the potential window, the measured electrical conductivity and, last but not least, the safety.
7
Третьяков, Дмитро Олегович. "Фізико-хімічні властивості систем сіль літію (LiBF4, LiCIO4, LiNO3, LiSO3CF3, LiN(SO2CF3)2) - апротонний диполярний розчинник ((CH3)2SO2, (C2H5)2SO2,(CH3)2SO, C3H4O3, C8H18O4)." Diss. of Candidate of Chemical Sciences, Міжвідомче відділ. електрохім. енергетики Нац. акад. наук України, 2012.
Find full text
8
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.
Full text
9
Cheng, Yi-Ting, and 鄭宜庭. "The Effect of Pd and Co Additives on the Enhancement of the Dehydrogenation Characteristics for LiBH4 and LiBH4+2LiNH2 systems." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/87727432772319427866.
Full textAbstract:
碩士國立中央大學
材料科學與工程研究所
99
LiBH4 is a potential hydrogen storage material and gains lots of interests recently due to the extremely high hydrogen capacity (18.4 wt%). However, the initial decomposition temperature (Ti) and main dehydrogenation temperature (Tm) of LiBH4 are as high as 567 and 754 K, respectively. In order to overcome the drawbacks, there are several approaches developed to modify the system thermodynamically or kinetically. In this study, LiBH4 is modified by various additives or mixing with LiNH2 to form a new Li-B-N-H quaternary hydride by ball-milling process. Besides, their dehydrogenation properties are analyzed through temperature programmed reduction (TPR) and temperature programmed dehydrogenation-mass spectrometers (TPD-MS), and the phase structures of the systems are characterized by the X-ray powder diffraction (XRD) method. Based on the results, it can be observed that the dehydrogenation properties of the LiBH4 can be successfully improved by doping 33 wt% of Pd-Co/C additives, and among the three different samples, Pd25Co75/C doped sample shows the optimal enhancement in promoting the dehydrogenation properties of LiBH4¬ by reducing the Ti to 523 K with the capacity as 10.5 wt%. Besides, it is found out that when the Co content in the additives increases, the Tis gradually decrease and capacities gently increase. Moreover, for the system modified by various amounts of Pd-Co/C, the results reveal that when the system is modified by 50 wt% of Pd-Co/C, Pd50Co50/C doped sample has better performance than Pd75Co25/C and Pd25Co75/C doped samples, which Ti and Tm can decrease to 533 and 639 K with 10 wt% of hydrogen desorbed. On the other hand, for 33 wt% of Pd-Co/C modified LiBH4+2LiNH2 binary system, the sample doped with Pd50Co50/C shows the effective modification, and the Ti is dramatically reduced from 523 K of the pristine binary system to 396 K and the capacity is 9.5 wt%. In terms of various metal (Pd and Co) chlorides and hydroxides modified LiBH4 and binary systems, the improvement of the dehydrogenation properties can both be observed. However, the reasons of the enhancements by metal chlorides and hydroxides may be different. For LiBH4 systems, the metal chlorides modified samples may have some ion exchange reactions and then form the unstable transition metal borohydrides during the heating process, thus the dehydrogenation properties can be enhanced. However, for metal hydroxides doped samples, the enhancement may be ascribed as the combinational effects of hydrolysis and redox reactions during the decomposition processes. On the other hand, for the metal (Pd and Co) chlorides and hydroxides modified binary systems, although the Tis and Tms can both significantly decrease to lower temperature ranges, the capacities of the samples modified by metal hydroxides also conspicuously reduce. Therefore, metal chlorides modified binary samples shows the better performance in improving the dehydrogenation properties than metal hydroxides.
10
CHAN, CHEN-WEI, and 詹鎮瑋. "Computational Study on the Structuresof (LiBH4)n，n=1~12 Clusters forHydrogen Storage." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/41085857259458507073.
Full textAbstract:
碩士中原大學
化學研究所
102
In the present study, we used density functional theory with B3LYP/6-311g++(d, p) method to calculate the structures, frequencies and energies of (LiBH4)n, n=1~12 clusters which has been known as a candidate hydrogen storage materials. We found that each cluster has several isomers. In order to enhance the hydrogen storage capacity of (LiBH4)n clusters, we added excess electrons to(LiBH4)n clusters. Our calculations show that the hydrogen storage capacity as well as the weight percent is improved with the existence of excess electrons. In addition, we also analyzed the distribution of the charge.
11
Ciou, Jheng-ci, and 邱鉦琪. "Promotion of Dehydrogenation Characteristics for LiBH4 by Addition of PdNi(OH)x Catalysts." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/56590732064824469153.
Full textAbstract:
碩士國立中央大學
材料科學與工程研究所
98
H2 is viewed as one of the promising clean fuels of the future. The H2 economy involves three important areas: production, storage, and use.Among them, developing effective H2 storage methods and materials for transportation is a key challenge for basic research and a crucial factor in achieving the H2 economy. LiBH4 is a potential H2 storage material owing to its high theoretical H2 capacity (18.5 wt% H2). In this study, the as-received LiBH4 is modified by Pd-Ni(OH)x additives and their dehydrogenation properties are investigated by a technique of temperature programmed reduction (TPR), thermogravimetric analyzer (TGA), and temperature programmed dehydrogenation-mass spectrometers (TPD-MS). The phase structures of the modified LiBH4 before and after dehydrogenation are analyzed by the X-ray powder diffraction (XRD) method. For the Pd-Ni(OH)x modified LiBH4, it presents superior dehydrogenation kinetics, and its Tm (the main dehydrogenation peak) is changed from 740 to 370 K, suggesting that the Pd-Ni(OH)x additive can effectively reduce LiBH4 dehydrogenation temperature. Addition of Pd-Ni(OH)x into LiBH4 changes their dehydrogenation properties and reaction kinetics. When the amount of LiBH4 in the mixture increases from 0.33 to 0.67 (LiBH4: Pd-Ni(OH)x = 1:2 to 2:1 for C2 and C0.5), their desorption capacity increases and Tm decreases from 1.5 to 6.5 wt% and 740 to nearby 340 K, respectively. Among them, the C0.5 sample presents the superior dehydrogenation kinetics, and after dehydrogenation, LiBH4, Pd, Ni and Ni(OH)2 in the C0.5 sample transfer to Li6B4O9, PdB2, and Ni, respectively. For the dehydrogenation of various samples measured at 373 K for 1 h, the desorption capacity of modified LiBH4 is larger than that of un-modified one, implying that the modified sample displays good desorption kinetics at low temperatures. Moreover, in order to investigate the [OH]- group effect on their dehydrogenation, Pd-Ni(OH)x is heat treated at 473 K for 1 h, and Ni(OH)2 phase transfers to NiO. For the dehydrogenation of C0.5 and C0.5-H (LiBH4 modified by heated catalysts), the onset temperature of C0.5-H is higher than that of C0.5 while their desorption capacities are almost the same. This indicates that the [OH]- group does not influence the H2 capacities, but strongly affect the dehydrogenation kinetics of the mixtures. As a result, the Pd-Ni(OH)x-modified LiBH4 is a promising material for H2 storage materials.
12
Gulino, Valerio. "LiBH4 as Solid-state Electrolyte for Li-ion Batteries: Modelling, Synthesis, Characterization and Application." Doctoral thesis, 2020. http://hdl.handle.net/2318/1788797.
Full text
13
Chen, Wei-Chih, and 陳韋誌. "First-Principles Studies of Thermodynamic Properties and Dehydrogenation Processes of Hydrogen Storage Material (LiBH4)n Nanoclusters." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/93570751375375047601.
Full textAbstract:
碩士國立中山大學
物理學系研究所
102
Several experimental studies have found improved thermodynamic, kinetic, and reversibility properties when LiBH4 is confined in nano-porous materials. In this study, we used Monte Carlo method and genetic algorithm to search the conformations of reactant (LiBH4)n and one of products (LiB)n. Other products, Lin, Bn, and Li2BnHn, were obtained from literatures. We used the density functional theory to calculate the total energies of reactants and all possible products, and found that the stability of LiBH4 nanoclusters have only little difference compared with that of bulk-LiBH4. However, for the products, the stabilities decrease with reducing sizes. This phenomenon indicates nano-LiBH4 would have higher reaction temperatures. We also investigated the reaction paths of nano-LiBH4, and the results show that the reaction path change from bulk-phase reaction (LiBH4 → LiH + B + 3/2H2) to ((LiBH4)n → (LiB)n + 2nH2) after reducing size. We also found intermediate compound Li2BnHn might appear dehydrogenation. The possible intermediate compounds of (LiBH4)m(m=2,3,4,6) were further included in the calculations to understand the hydrogenation releasing processes. Our results show that different (LiBH4)m have different hydrogen release properties. When m=3 and 6, under 1 bar, both of them release hydrogen rapidly in small temperature interval near their starting points of hydrogen release. When m=2 and 4, we found the amount of releasing hydrogen has a linear relation with temperature near their starting points. However, our results do not replicate experimental results due to the exclusion of the substrate effects i.e. to the nano-porous materials used in experiments which improve the thermodynamic properties of nano-LiBH4.
14
Hu, Zhe-yuan, and 胡哲源. "The Effects of Metal (Ce, Co and Sn) Chlorides and Oxides Additives on the Enhancement of the Dehydrogenation Characteristics for LiBH4." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/21242421357135946550.
Full textAbstract:
碩士國立中央大學
材料科學與工程研究所
100
LiBH4 is a potential hydrogen storage material and gains lots of interests recently due to its extremely high hydrogen capacity (18.4 wt%). However, the initial decomposition (Ti) and main dehydrogenation temperatures (Tm) of LiBH4 are as high as 560 and 750 K, respectively. In order to overcome the drawbacks, several approaches have been developed to modify the system thermodynamically or kinetically. In this study, the effects of metal chlorides (CeCl3, CoCl2 and SnCl2), metal oxides (CeO2, CoO and SnO2), and carbon supported metal oxides (CeO2/C, CoO/C and SnO2/C) additions on promoting the dehydrogenation properties of LiBH4 have been investigated. The structures and metal oxides loadings of as-prepared CeO2/C, CoO/C and SnO2/C additives are measured by X-ray diffraction (XRD) and thermal gravimetric analysis (TGA), respectively. Furthermore, the dehydrogenation behavior of the fresh and modified LiBH4 is analyzed by temperature programmed reduction (TPR) and temperature programmed desorption–mass spectrometer (TPD-MS). Besides, X-ray absorption near-edge structure (XANES) is applied to detect the oxidation states of additives before and after dehydrogenation. Based on the results, it can be observed that the dehydrogenation properties of the LiBH4 can be successfully improved by doping 33 wt% of metal chlorides, metal oxides and carbon supported metal oxides. Among the three different systems, the metal Co shows the best performance in reducing the reaction kinetic barrier of LiBH4 whether it is in chloride or oxide forms. CoCl2 and CoO doped samples have the Tm to 564 and 486 K with the capacity as 14.5 and 15.5 wt%, respectively. In terms of various metal (Ce, Co and Sn) chlorides and oxides modified LiBH4, the improvement of the dehydrogenation properties can both be observed. For the metal chlorides modified samples, the enhancement may be due to some ion exchange reactions and then formation of the unstable transition metal borohydrides during the heating process. On the other hand, for metal oxides doped samples, the promotion may be ascribed as the effects of reduction reactions during the decomposition processes. In terms of the LiBH4 modified by carbon supported metal oxides, although the Ti can dramatically reduce except LiBH4/CeO2(C)-2, their capacities also conspicuously reduce. It is speculated that the promotion effect is owing to the increased contact area and formation of composite material between metal oxides and LiBH4 during the ball-milling process. Moreover, the XANES results show the reduction reaction between metal chlorides and LiBH4 during the dehydrogenation process occurs, which promotes the dehydrogenation reaction.
15
Tsai, Jih-Wei, and 蔡日偉. "Molecular Simulations of the Conductivities for LiBF4、LiPF6 and LiBF4/ Trimethyl Phosphate in Propylene Carbonate." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/05525140194548522221.
Full textAbstract:
碩士國立成功大學
化學系碩博士班
93
Molecular dynamics simulations have been used to study the diffusivity, conductivity, coordination and association properties for LiBF4 in Propylene carbonate (PC) and PC/Trimethyl phosphate (TMP) at 298 K. The results were compared with those of LiPF6-PC system. The simulated diffusion coefficients of Li+、F and H atoms agree with the NMR measurements. In addition, the computed specific conductivities have the same trend with experiment. It was shown that the high salt concentration facilitates the ion pair formation, but decreases the solvent coordination. At high salt concentrations, the association between Li+ and anion are serve which increases the average cluster size and reduces the fraction of free ions.As fire-resistant agent TMP, a Lewis base,is added,it binds strongly with Li+ ion, therefore suppressing the ion-pair formation and improving the conductivity. Since the partial charge of fluorine atom in BF4- is higher than that of PF6-, BF4- arrarcts Li+ more favorably to form ion-pair, leading a superior conductivity to LiPF6-PC system,which is in accord with experiment.
16
Lin, Cheng-hsing, and 林政興. "Ionic conductivity of Poly(vinyl alcohol-co-ethylene glycol)/LiBF4." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/32143685278595413624.
Full textAbstract:
碩士義守大學
生物技術與化學工程研究所碩士班
98
The ionic conductivity of poly(vinyl alcohol-co-ethylene glycol) (PVAEG) doped with lithium tetrafluoroborate (LiBF4) was studied. Experimental techniques such as X-ray diffraction (XRD) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy and optical microscopy were employed to characterize the film structure, while techniques such as dielectric spectroscopy and four point probe were used to study the ionic conductivity. The intensity of XRD peak decreased with increasing LiBF4 content. The optical microscopy study revealed that LIBF4 began to precipitate when the EG/Li molar ratio was greater than 6. There was an optimal LiBF4 concentration, EG/Li = 8, at which the ionic conductivity reached the maximum value of 2.34×10-7 S/cm. With LiBF4 concentrations higher than EG/Li=8, ion aggregation was favored and the conductivity began to decrease thereafter. The ionic conduction behaviors investigated using the dielectric spectroscopy technique also gave a result similar to that given by the 4-point probe method.
17
Yeh, Ze-Yi, and 葉則易. "Molecular Simulations of the Conductivities in EMIBF4 / LiBF4 Binary System." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/89145736211026513852.
Full textAbstract:
碩士國立成功大學
化學系碩博士班
94
Molecular dynamic simulation method has been employed to study the influences of the temperature（313, 343 K）and LiBF4 concentration（0, 1.0, 1.5, 2.0 M）on the ionic conductivity, coordination and association of the EMIBF4/LiBF4 binary system. The diffusion coefficients of the species H, F, Li＋ were computed firstly from the plot of the mean-squared displacement. With the aid of Nernst-Einstein equation and the calculated free ion probability, the specific conductivity of the system was estimated. The radial distribution functions were then analyzed to understand the ionic interaction, coordination and aggregation within the system. It’s known from the simulation that the diffusion coefficient and specific conductivity decreases with the increasing LiBF4 concentration and decreasing temperature, which is in accord with experiment. The number of the hydrogen-bond forming F atoms of BF4－ around the acidic hydrogen atom of EMI＋ is between 2.23 and 2.36 at 313 K, depending on concentration. The number decreases with the increasing temperature. At 313 K and 1.0 M, the number of coordinating BF4－ anions around Li＋and EMI＋ cation is 2.77 and 8.27, respectively. The coordination number increases with the increment of LiBF4 concentration. The increase of temperature facilitates the coordination of BF4－ around Li＋, but has virturally no effect for EMI＋. Various forms of ionic clusters were found in the solution, such as monomer（Li＋, EMI＋, BF4－）, dimmer（LiBF4, EMIBF4）, trimer（[Li(BF4)2]－, [EMI(BF4)2]－, [Li(EMI)(BF4)]＋, [Li2BF4]＋ or [(EMI)2BF4]＋）, etc. The variations of their fractions with LiBF4 concentration and temperature were obtained from the present simulation.
18
Chen, Hui-Lung, and 陳輝龍. "Molecular dynamics simulations of the conductivity for LiBF4 in mixed organic solvent." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/86850097524014310366.
Full textAbstract:
碩士國立成功大學
化學系
89
Molecular dynamic simulation method has been used to study the conducting behavior of LiBF4 in diethyl carbonate(DEC)、propylene carbonate(PC) and their mixing solvent. The diffusion coefficient of lithium ion in the solution was computed firstly from its mean-square displacement. Utilizations were then made of the Nernst-Einstein equation to estimate the conductivity. The probability of finding free lithium ion was also calculated to revise the computed conductivity. The average numbers of solvent and anion around the lithium ion were also calculated from the plot of radial distribution function. Finally, the stress autocorrelation function vs. time was plotted to estimate the viscosity of systems. The computed conductivity increases initially, and then decreases with the increase of the salt concentration for DEC/PC mixed system(mass ratio 1:1). The trend is consistent with that obtained by Moumouzias. At a constant salt concentration of 0.5m, the computed conductivity is found to decrease monotonically with the increase of DEC content. The plot of radial distribution function reveals that solvent molecules lie more closely to lithium ion than anions. That is, the positive and negative ions of the lithium salts are separated by solvent molecules. Moreover, the number of molecules in the first solvation shell is close to 4, whatever the salt concentration and solvent composition are. The result is consistent with the tetrahedral arrangement conjectured by Soetens. But it is known from the time evolution of the distance between lithium ion and nearby PC molecules that the exchange of solvent molecules between the first and the second solvation shells of the lithium ion is frequent. Our result differs from that reported by Soetens where four solvent molecules are found to be bounded strongly with lithium ion during the whole simulation. The discrepancy is ascribed to the relatively high salt concentration used in the present work, which facilitate the attraction of solvent shell molecules by other positive and negative ions. The simulation also shows that the viscosity of salt solution is higher than that of pure solvent and that the viscosity increases further as more salts are added.
19
Chen, Meng-Kai, and 陳孟概. "The study of lithium ion battery prepared by LiBF4 added polyacrylonitrile polymer electrolyte." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/81778943488267433974.
Full textAbstract:
碩士國立中興大學
物理學系所
100
A battery is prepared using lithium as an anode electrode and lithium iron phosphate as a chathode electrode. The gelled polymer electrolyte is prepared by mixing LiBF4 lithium salts, polyacrylonitrile and ethylene carbonate. Ac impedance is employed to elucidate the lithium ion transport between the interfaces of electrolyte and electrodes. Cyclic voltammetry is used to study the electrochemical reaction of the battery. The charge/discharge property of the battery is explored by a multi-cell battery charger/discharger. The results indicate that, as the content of LiBF4 lithium salt increases, charge capacity of the battery increases, while, both the resistance of the solid electrolyte interface (SEI) and the irreversible capacity decrease. However, it is harmful to the battery properties as the content of LiBF4 lithium salt exceeding the solubility of the polymer. It is helpful to the electrical properties of the battery by increasing polyacrylonitrile content. However, this will increase the assembling difficulty of the battery.
20
Hsueh, Wen-Kai, and 薛文凱. "The study of lithium ion battery prepared by LiBF4 added Polyvinylidene fluoride polymer electrolyte." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/37011497771778616628.
Full textAbstract:
碩士國立中興大學
物理學系所
100
In a lithium ion battery, suitable electrolyte can optimize the performance of the battery system. Using LiFePO4 as cathode material and lithium as the anode material, gel electrolyte samples, made of different ratios of PVDF、LiBF4、EC、PC mixtures, were investigated by conductingAC impedance and cyclic voltammetry. AC impedance results indicated that the conductivity of gel electrolytes increase with the rise of PVDF content ratio. Cyclic voltammetry(CV) diagrams showed both oxidation peak and reduction peak are single peaks and the peak voltages didn’t vary with the electrolyte composition. Also, oxidation-reduction peak area and charge/discharge tests measurements revealed that the irreversible effect is less than 10% in this battery system. Furthermore, the charge/discharge tests demonstrated a stable charge platform at 3.6V and a discharge platform at 3.3V in this battery system. In the charge/discharge cycles, the battery capacity decreased with the charge rate rise.
21
Shen, Zheng-Xun, and 沈政勳. "Molecular dynamics simulations of the conductivities for LiN(SO2CF3)2 and LiBF4 in γ-butyrolactone." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/65693656362001602151.
Full textAbstract:
碩士國立成功大學
化學系碩博士班
91
Molecular dynamics simulation has been applied to investigate the conducting behavior and salt-solvent interactions for LiBF4 and LiN(CF3SO2)2 (LiTFSI) in γ-butyrolactone (GBL). Simulations were performed at salt concentrations of 0.5, 1.0, and 1.5 M at 295 K, to mimic the experiment at conditions of the previous research conducted by Aihara et al. The simulated diffusion coefficients for Li+, anion, and solvent decrease with the increase of concentration, but the conductivities increases, due to the increasing number of conducting species. After revision with the probability of free lithium ion, the computed conductivities are close to the experiment as values. At high salt concentrations, the association between Li+ and anions becomes more sever, resulting in the formation of large cluster and reduction of the number of free ions. At 1.5 M LiBF4 concentration, there are 6.3 solvent molecules and 1.7 anions within the first coordination sphere (about 6.35 Å) of Li+. The corresponding values are 6.1 and 1.8 for LiTFSI, respectively. Moreover, the probability to find free Li+ ion is 11.0 ﹪for the former and 7.2 ﹪for the latter, indicating a stronger tendency for Li+─TFSI- association. As the concentration is reduced to 0.5 M, the number of coordinating solvent molecules increases in contrast to the reduction of anions.