Search

Your search keyword '"Kondo, Yasuhito"' showing total 48 results
Start Over Author "Kondo, Yasuhito"
48 results on '"Kondo, Yasuhito"'

16. Effects of Lithium Bis(oxalate)borate Electrolyte Additive on the Formation of a Solid Electrolyte Interphase on Amorphous Carbon Electrodes by OperandoTime-Slicing Neutron Reflectometry

Author

Kawaura, Hiroyuki, Harada, Masashi, Kondo, Yasuhito, Mizutani, Mamoru, Takahashi, Naoko, and Yamada, Norifumi L.

Abstract

Comprehensive analyses were performed using neutron reflectivity and hard X-ray photoelectron spectroscopy to understand the structure and composition of the solid electrolyte interphase (SEI) layer during charge–discharge processes and because of the addition of lithium bis(oxalate)borate (LiBOB) to improve the battery performance. The chemical composition of the SEI was assessed using these methods, and the amount of Li+intercalated in the anode during the electrochemical reaction was evaluated. The results demonstrated that Li2C2O4was produced initially but later decomposed to Li2CO3on the first charge cycle. Presumably, the SEI layer formed by the decomposition of LiBOB was a single dense layer and chemically stable during the further charge–discharge processes owing to the difference in the reaction process. Therefore, the reduced Li+transfer resistance and charging capacity accounted for the substantial improvement contributed by adding LiBOB. Moreover, the charges used for the intercalation of Li+and SEI formation during the two-cycle processes were analyzed. The addition of LiBOB increased the discharge capacity of the anode and provided an additional charge used for SEI formation, presumably for decomposing Li2C2O4, which could reflect the durability of the Li-ion batteries. The electrode, electrolyte, and charge–discharge reactions affect the SEI properties and consequently the electrochemical reactions. Therefore, additional investigations under different charge–discharge conditions would reveal important characteristics such as the charge and discharge efficiency, output performance, and safety.

Published
2022
Full Text
View/download PDF

19. Battery Materials Research with Muon Beam

Author

Umegaki, Izumi, primary, Higuchi, Yuki, additional, Nozaki, Hiroshi, additional, Kondo, Yasuhito, additional, Oka, Hideaki, additional, Makimura, Yoshinari, additional, Forslund, Ola K., additional, Månsson, Martin, additional, Cottrell, Stephen P., additional, and Sugiyama, Jun, additional

Published
2019
Full Text
View/download PDF

20. Battery Materials Research with Muon Beam

Author

Umegaki, Izumi, Higuchi, Yuki, Nozaki, Hiroshi, Kondo, Yasuhito, Oka, Hideaki, Makimura, Yoshinari, Forslund, Ola Kenji, Månsson, Martin, Cottrell, Stephen P., Sugiyama, Jun, Umegaki, Izumi, Higuchi, Yuki, Nozaki, Hiroshi, Kondo, Yasuhito, Oka, Hideaki, Makimura, Yoshinari, Forslund, Ola Kenji, Månsson, Martin, Cottrell, Stephen P., and Sugiyama, Jun

Abstract

We applied a positive muon spin rotation and relaxation (μ+SR) technique to battery materials research by investigating Li diffusion in cathode and electrolyte materials. Recently, we have found that Li diffusion in graphite, which is commonly used as an anode material in Li-ion batteries, is detectable with μ+SR. Following upon the initial μ+SR measurements on the Li intercalated graphites, C6Li and C12Li, μ+SR spectra were also measured for C12Li0.92 and C18Li0.90 posing a slightly different occupancy in the same stage structure as those of C6Li and C12Li. The temperature dependence of diffusive nature in C12Li0.92 and C18Li0.90 was found to be similar in nature to those in C6Li and C12Li. Such a diffusion was found to start to occur approximately by 50 K lower than those of C6Li and C12Li. This suggests that Li starts to diffuse at lower temperatures in the nonstoichiometric Li intercalated graphite samples than that in the stoichiometric samples., QC 20200205

Published
2019
Full Text
View/download PDF

21. Capacity-Fading Mechanisms of LiNiO2-Based Lithium-Ion Batteries : I. Analysis by Electrochemical and Spectroscopic Examination

Author

Sasaki, Tsuyoshi, Nonaka, Takamasa, Oka, Hideaki, Okuda, Chikaaki, Itou, Yuichi, Kondo, Yasuhito, Takeuchi, Yoji, Ukyo, Yoshio, Tatsumi, Kazuyoshi, and Muto, Shunsuke

Subjects
genetic structures, sense organs, behavioral disciplines and activities, eye diseases, psychological phenomena and processes
Abstract

The mechanism for capacity fade of lithium-ion batteries with LiNi0.8Co0.15Al0.05O2 as a positive electrode material associated with cycling at elevated temperatures was investigated by the combination of electrochemical and spectroscopic methods. The total capacity fade of the battery after charge/discharge cycle test at 80°C was found to be almost explained by the capacity fade of the positive electrode, which indicates that the degradation of the positive electrode is mainly responsible for capacity fade of the battery at this temperature. Quantitative analyses revealed a strong positive correlation between the capacity fade of the positive electrode and the amount of inactive Ni ions in the active material after the cycling test. It is concluded that the capacity fade is mainly caused by the formation of inactive Ni(II) and Ni(III), presumably associated with oxygen loss in the active materials, which act as obstacles to Li intercalation/deintercalation.

Published
2009

22. OperandoTime-Slicing Neutron Reflectometry Measurements of Solid Electrolyte Interphase Formation on Amorphous Carbon Surfaces of a Li-Ion Battery

Author

Kawaura, Hiroyuki, Harada, Masashi, Kondo, Yasuhito, Mizutani, Mamoru, Takahashi, Naoko, and Yamada, Norifumi L

Abstract

A solid-electrolyte interphase (SEI) is widely recognized to improve the safety and durability of lithium ion batteries. In this work, we investigate the structure and chemistry of the carbon electrode and SEI in operandoduring two-cycle battery operation for further understanding of the electrochemical reactions, and the effect of the hysteresis using in situneutron reflectivity (NR) and ex situhard X-ray photoelectron spectroscopy (HAXPES). The results revealed the structural evolution of the electrode and SEI layer, such as the change in the thickness and scattering length density (SLD) in connection with the chemical composition during the lithiation/delithiation processes. Next, the HAXPES results at the point before and after the charging/discharging process revealed the change in the chemical composition of the SEI layer due to the chemical reactions on the formation/degradation. Based on the combination of these analyses, the results showed that the SLDs of the SEI layer evaluated by NR analysis were consistent with those determined by HAXPES. Concerning the difference in the first and second cycles, the structure of the amorphous carbon electrode exhibited hysteresis due to lithiation/delithiation, whereas the chemical composition of the SEI layer after charge/discharge was almost independent of the number of cycles.We report operando measurements of solid-electrolyte interphase (SEI) formation on a carbon electrode using operandoneutron reflectivity and ex situhard X-ray photoelectron spectroscopy. The results indicate that, for both SEI and the electrode, the thickness and composition change during a lithiation and delithiation reaction. Such an operando technique clearly provides a new insight for the formation of SEIs.

Published
2020
Full Text
View/download PDF

23. Li-ion diffusion in Li intercalated graphite C6Li and C12Li probed by mu+SR

Author

Umegaki, Izumi, Kawauchi, Shigehiro, Sawada, Hiroshi, Nozaki, Hiroshi, Higuchi, Yuki, Miwa, Kazutoshi, Kondo, Yasuhito, Månsson, Martin, Telling, Mark, Coomer, Fiona C., Cottrell, Stephen P., Sasaki, Tsuyoshi, Kobayashi, Tetsuro, Sugiyama, Jun, Umegaki, Izumi, Kawauchi, Shigehiro, Sawada, Hiroshi, Nozaki, Hiroshi, Higuchi, Yuki, Miwa, Kazutoshi, Kondo, Yasuhito, Månsson, Martin, Telling, Mark, Coomer, Fiona C., Cottrell, Stephen P., Sasaki, Tsuyoshi, Kobayashi, Tetsuro, and Sugiyama, Jun

Abstract

In order to study a diffusive behavior of Li+ in Li intercalated graphites, we have measured muon spin relaxation (mu+SR) spectra for C6Li and C12Li synthesized with an electrochemical reaction between Li and graphite in a Li-ion battery. For both compounds, it was found that Li+ ions start to diffuse above 230 K and the diffusive behavior obeys a thermal activation process. The activation energy (E-a) for C6Li is obtained as 270(5) meV, while E-a = 170(20) meV for C12Li. Assuming a jump diffusion of Li+ in the Li layer of C6Li and C12Li, a self-diffusion coefficient D-Li at 310 K was estimated as 7.6(3) x 10(-11) (cm(2) s(-1)) in C6Li and 14.6(4) x 10(-11) (cm(2) s(-1)) in C12Li., QC 20170816

Published
2017
Full Text
View/download PDF

24. Improvement of the Specific Power of Paste-Type Positive Electrodes for Ni-MH Batteries

Author

Towata Shinichi, Kondo Yasuhito, and Shinya Morishita

Subjects
Materials science, Electrode, General Chemistry, Composite material, Power density
Abstract

ニッケル-水素(Ni–MH)電池で用いられるペースト式正極を高出力化するため，反応晶析法にて合成した種々の大きさの正極活物質粒子を用いて粒径と正極特性との関係を検討した．正極活物質の粒径を最適化することにより正極の出力密度を約3倍向上させることができた．得られたペースト式正極の出力密度は焼結式正極と同等で，放電容量は約20%増加した．

Published
2002
Full Text
View/download PDF

25. Quantitative Analysis of Corrosion Layer on LaNi5 Based Hydrogen Storage Alloys

Author

Towata Shinichi, Shinya Morishita, Yutaka Ohya, and Kondo Yasuhito

Subjects
Hydrogen storage, Materials science, Metallurgy, General Chemistry, Quantitative analysis (chemistry), Corrosion
Abstract

希土類系水素吸蔵合金とその腐食生成物(希土類系水酸化物 + ニッケル，コバルトの金属微粒子)のクロム酸水溶液への溶解特性を検討した．合金表面の水酸化物層は，合金素地を溶解することなく5質量%のクロム酸水溶液に溶解した．溶液中の各合金元素量を高周波プラズマ発光分光分析法(ICP-AES)にて測定することにより，水酸化物層の組成が求められた．ニッケル，コバルトの金属微粒子の生成量は磁気測定によって見積もられ，合金の腐食層の組成を定量的に分析できた．

Published
2001
Full Text
View/download PDF

26. Analysis of the Activation Mechanism of Hydrogen Storage Alloy Negative Electrodes Modified by Nickel Particles

Author

Katsushi Abe, Towata Shinichi, Kondo Yasuhito, Hiroshi Fukasaku, Yutaka Ohya, and Shinya Morishita

Subjects
Mechanism (engineering), Hydrogen storage, Nickel, Materials science, chemistry, Cryo-adsorption, Alloy, Inorganic chemistry, Electrode, engineering, chemistry.chemical_element, General Chemistry, engineering.material
Abstract

ニッケル微粒子が添加された水素吸蔵合金負極を使用したNi-MH電池では,負極の初期活性化が促進された。負極の複素インピーダンス解析ならびに添加されたニッケル微粒子の比表面積と酸素含有量の測定より,ニッケル微粒子表面の微細な凹凸部が充放電反応の活性点として作用し,生成した水素の吸蔵によって合金に割れが生じて新たな活性点が生成されるため負極の初期活性化が促進されると推定された。

Published
2000
Full Text
View/download PDF

27. Li-ion diffusion in Li intercalated graphite C6Li and C12Li probed by μ+SR

Author

Umegaki, Izumi, primary, Kawauchi, Shigehiro, additional, Sawada, Hiroshi, additional, Nozaki, Hiroshi, additional, Higuchi, Yuki, additional, Miwa, Kazutoshi, additional, Kondo, Yasuhito, additional, Månsson, Martin, additional, Telling, Mark, additional, Coomer, Fiona C., additional, Cottrell, Stephen P., additional, Sasaki, Tsuyoshi, additional, Kobayashi, Tetsuro, additional, and Sugiyama, Jun, additional

Published
2017
Full Text
View/download PDF

31. Li-ion diffusion in Li intercalated graphite C6Li and C12Li probed by μ+SR.

Author

Umegaki, Izumi, Kawauchi, Shigehiro, Sawada, Hiroshi, Nozaki, Hiroshi, Higuchi, Yuki, Miwa, Kazutoshi, Kondo, Yasuhito, Månsson, Martin, Telling, Mark, Coomer, Fiona C., Cottrell, Stephen P., Sasaki, Tsuyoshi, Kobayashi, Tetsuro, and Sugiyama, Jun

Abstract

In order to study a diffusive behavior of Li+ in Li intercalated graphites, we have measured muon spin relaxation (μ+SR) spectra for C6Li and C12Li synthesized with an electrochemical reaction between Li and graphite in a Li-ion battery. For both compounds, it was found that Li+ ions start to diffuse above 230 K and the diffusive behavior obeys a thermal activation process. The activation energy (Ea) for C6Li is obtained as 270(5) meV, while Ea = 170(20) meV for C12Li. Assuming a jump diffusion of Li+ in the Li layer of C6Li and C12Li, a self-diffusion coefficient DLi at 310 K was estimated as 7.6(3) × 10−11 (cm2 s−1) in C6Li and 14.6(4) × 10−11 (cm2 s−1) in C12Li. [ABSTRACT FROM AUTHOR]

Published
2017
Full Text
View/download PDF

47. Quantification of side reactions in lithium-ion batteries during overcharging at elevated temperatures.

Author

Oka, Hideaki, Nonaka, Takamasa, Kondo, Yasuhito, and Makimura, Yoshinari

Subjects
*HIGH temperatures, *TEMPERATURE control, *NEGATIVE electrode, *ELECTRIC batteries, *EXOTHERMIC reactions, *LITHIUM-ion batteries
Abstract

Lithium-ion batteries experience complex reactions between the electrodes and the electrolyte under non-standard conditions. Investigating these reactions is crucial for ensuring battery durability and safety. In this study, we develop an electrochemical cell capable of controlled overcharging and temperature regulation between 30 and 100 °C. The charge-discharge performance of the cell is evaluated after overcharging. By utilizing synchrotron radiation for X-ray diffraction and absorption fine structure analysis, we track the electronic state of the positive electrode and the crystal structure of the negative electrode during heated overcharging. Our results reveal increased side reactions in the positive electrode at higher temperatures during overcharging, while the negative electrode displays a gradual increase in side reactions in the normal charge-discharge region with increasing temperature. Specifically, at 100 °C, side reactions in the overcharging regions consume 86.5% and 66.1% of the current at the positive and negative electrodes, respectively. These side reactions are induced by the electrolyte oxidative decomposition at the positive electrode. Moreover, they initiate Joule heating during battery overcharging, promoting side reactions and leading to exothermic reactions between the electrodes and electrolyte. [Display omitted] • Side reactions in LIBs during overcharging at elevated temperatures were investigated. • Operando X-ray analysis and electrochemical evaluation were conducted. • Side reactions were quantitatively identified at normal and overcharging regions. • Side reactions at positive electrode induced those at negative electrodes. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

48. Li-ion diffusion in Li intercalated graphite C 6 Li and C 12 Li probed by μ + SR.

Author

Umegaki I, Kawauchi S, Sawada H, Nozaki H, Higuchi Y, Miwa K, Kondo Y, Månsson M, Telling M, Coomer FC, Cottrell SP, Sasaki T, Kobayashi T, and Sugiyama J

Abstract

In order to study a diffusive behavior of Li + in Li intercalated graphites, we have measured muon spin relaxation (μ + SR) spectra for C 6 Li and C 12 Li synthesized with an electrochemical reaction between Li and graphite in a Li-ion battery. For both compounds, it was found that Li + ions start to diffuse above 230 K and the diffusive behavior obeys a thermal activation process. The activation energy (E a ) for C 6 Li is obtained as 270(5) meV, while E a = 170(20) meV for C 12 Li. Assuming a jump diffusion of Li + in the Li layer of C 6 Li and C 12 Li, a self-diffusion coefficient D Li at 310 K was estimated as 7.6(3) × 10 -11 (cm 2 s -1 ) in C 6 Li and 14.6(4) × 10 -11 (cm 2 s -1 ) in C 12 Li.

Published
2017
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results