その場プローブ顕微鏡を用いたリチウムイオン電池用黒鉛負極に関する研究

京都大学0048新制・課程博士博士(工学)甲第20000号工博第4244号新制||工||1657(附属図書館)33096京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 安部 武志, 教授 作花 哲夫, 教授 阿部 竜学位規則第4条第1項該当Doctor of Philosophy (Engineering)Kyoto UniversityDFA

Electrochemical Solvent Cointercalation into Graphite in Propylene Carbonate-Based Electrolytes: A Chronopotentiometric Characterization

Interfacial reactions strongly influence the performance of lithium-ion batteries, with the main interfacial reaction between graphite and propylene carbonate- (PC-) based electrolytes corresponding to solvent cointercalation. Herein, the redox reactions of solvated lithium ions occurring at the graphite interface in 1 M·LiClO4/PC were probed by chronopotentiometry, in situ atomic force microscopy (AFM), and in situ Raman spectroscopy. The obtained results revealed that high coulombic efficiency (97.5%) can be achieved at high current density, additionally showing the strong influence of charge capacity on the above redox reactions. Moreover, AFM imaging indicated the occurrence of solvent cointercalation during the first reduction, as reflected by the presence of hills and blisters on the basal plane of highly oriented pyrolytic graphite subjected to the above process

Determination of Cyclability of Li/FeS2 Batteries Based on Measurement of Coulombic Efficiency

The electrochemical performance of negative electrodes based on different FeS2 samples was investigated. The study demonstrated a correlation between the coulombic efficiency obtained over 60 cycles and the capacity loss rate evaluated over 15 cycles. The accuracy of the coulombic efficiency and capacity loss rate measurements was advantageous for predicting the aging behavior of half-cells over a short-term test. A suggested classification of the coulombic efficiency and verification via a numerical analysis were proposed to determine the fading rate of batteries during the galvanostatic test

Improvement in the Electrochemical Properties of Lithium Metal by Heat Treatment: Changes in the Chemical Composition of Native and Solid Electrolyte Interphase Films

This study aims to improve the electrochemical properties of lithium metal for application as a negative electrode in high-energy-density batteries. Lithium metal was heat-treated at varying temperatures to modify the native and solid electrolyte interphase (SEI) films, which decreased the interfacial resistance between the lithium electrode and electrolyte, thereby improving the cycling performance. Moreover, the influence of the native and SEI films on lithium metals depended on the heat-treatment temperature. Accordingly, X-ray photoelectron spectroscopy (XPS) was performed to investigate the chemical composition of the native and SEI films on the heat-treated lithium metals before and after immersion in an organic electrolyte solution. The XPS results revealed the high dependence of the chemical composition of the outer layer of the native and SEI films on the heat-treatment temperature, implying that the native and SEI films can be effectively modified by heat treatment

Improvement in the Electrochemical Properties of Lithium Metal by Heat Treatment: Changes in the Chemical Composition of Native and Solid Electrolyte Interphase Films

This study aims to improve the electrochemical properties of lithium metal for application as a negative electrode in high-energy-density batteries. Lithium metal was heat-treated at varying temperatures to modify the native and solid electrolyte interphase (SEI) films, which decreased the interfacial resistance between the lithium electrode and electrolyte, thereby improving the cycling performance. Moreover, the influence of the native and SEI films on lithium metals depended on the heat-treatment temperature. Accordingly, X-ray photoelectron spectroscopy (XPS) was performed to investigate the chemical composition of the native and SEI films on the heat-treated lithium metals before and after immersion in an organic electrolyte solution. The XPS results revealed the high dependence of the chemical composition of the outer layer of the native and SEI films on the heat-treatment temperature, implying that the native and SEI films can be effectively modified by heat treatment

Electrochemical intercalation of Ca2+ ions into TiS2 in organic electrolytes at room temperature

This work investigates the electrochemical intercalation of Ca2+ ions into TiS2 in organic electrolytes at room temperature and demonstrates that successful intercalation/de-intercalation can be achieved using a 0.1 M solution of Ca(CF3SO3)2 in propylene carbonate (PC) as an electrolyte. Additionally, further performance (charge/discharge capacity, reversibility, and hysteresis) enhancement is observed when a 0.1 M solution of Ca(CF3SO3)2 in a 1:10 (mol/mol) mixture of PC and dimethyl carbonate (DMC) is employed, which is ascribed to the modulation of the solvation environment of Ca2+ ions by the use of the relatively low-polar DMC. Finally, the structural changes in TiS2 caused by Ca2+ intercalation/de-intercalation during charge/discharge are probed by in situ X-ray diffraction analysis. Keywords: Calcium-ion batteries, TiS2 electrode, Organic electrolyte, In situ X-ray diffraction analysi

Acute Pancreatitis and Rhabdomyolysis with Acute Kidney Injury following Multiple Wasp Stings

Multiple wasp stings can induce multiple organ dysfunction by toxic reactions. However, acute pancreatitis is a rare manifestation in wasp sting injury. A 74-year-old woman visited the emergency department by anaphylactic shock because of multiple wasp stings. Acute kidney injury, rhabdomyolysis, hepatotoxicity, and coagulopathy were developed next day. Serum amylase and lipase were elevated and an abdominal computed tomography revealed an acute pancreatitis. Urine output was recovered after 16 days of oliguria (below 500 ml/day). Her kidney, liver, and pancreas injury gradually improved after sessions of renal replacement therapy

Human 8-oxoguanine DNA glycosylase suppresses the oxidative stress induced apoptosis through a p53-mediated signaling pathway in human fibroblasts

Human 8-oxoguanine DNA glycosylase (hOGG1) is the main defense enzyme against mutagenic effects of cellular 7,8-dihydro-8-oxoguanine. In this study, we investigated the biological role of hOGG1 in DNA damage-related apoptosis induced by hydrogen peroxide (H(2)O(2))-derived oxidative stress. The down-regulated expression of hOGG1 by its small interfering RNA prominently triggers the H(2)O(2)-induced apoptosis in human fibroblasts GM00637 and human lung carcinoma H1299 cells via the p53-mediated apoptotic pathway. However, the apoptotic responses were specifically inhibited by hOGG1 overexpression. The p53-small interfering RNA transfection into the hOGG1-deficient GM00637 markedly inhibited the H(2)O(2)-induced activation of p53-downstream target proteins such as p21, Noxa, and caspase-3/7, which eventually resulted in the increased cell viability. Although the cell viability of hOGG1-knockdown H1299 p53 null cells was similar to that of the hOGG1 wild-type H1299, after the overexpression of p53 the hOGG1-knockdown H1299 showed the significantly decreased cell viability compared with that of the hOGG1 wild-type H1299 at the same experimental condition. Moreover, the array comparative genome hybridization analyses revealed that the hOGG1-deficient GM00637 showed more significant changes in the copy number of large regions of their chromosomes in response to H(2)O(2) treatment. Therefore, we suggest that although p53 is a major modulator of apoptosis, hOGG1 also plays a pivotal role in protecting cells against the H(2)O(2)-induced apoptosis at the upstream of the p53-dependent pathway to confer a survival advantage to human fibroblasts and human lung carcinomas through maintaining their genomic stability