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5 results on '"Shimooka Toshiharu"'

1. Temperature‐Inert Interface Enables Safe and Practical Energy‐Dense LiNi0.91Co0.07Mn0.02O2 Pouch Cells.

Author

Hou, Junxian, Shi, Qinyu, Feng, Xuning, Terada, Junpei, Wang, Li, Zhao, Liqi, Cao, Daihua, Yamazaki, Shigeaki, Xu, Chengshan, Qiu, Yue, Feng, Jing, Shimooka, Toshiharu, Peng, Yong, Xie, Yingchen, Zhu, Gaolong, Lu, Languang, Bao, Cheng, and Ouyang, Minggao

Subjects
PHASE transitions, PHOTOELECTRON spectroscopy, SOLID electrolytes, SILICA, THERMAL batteries
Abstract

Safety concerns significantly hinder the practical implementation of ultrahigh‐nickel cathodes in lithium‐ion batteries. The solid electrolyte interphase (SEI) derived from conventional ester‐based electrolyte is susceptible to thermal decomposition, resulting in battery safety degradation. Herein, a temperature‐inert and inorganic‐rich SEI is developed for the ultrahigh‐nickel LiNi0.91Co0.07Mn0.02O2|graphite (NCM91|Gr) battery by employing a flame‐retardant diluted weakly solvated electrolyte. Temperature‐dependent X‐ray photoelectron spectroscopy reveals that SEI's inorganic components of LiF, Li2SO3, Li2SO4, and Li3N exhibit exceptional thermotolerance under thermal attack. Further evidence from temperature‐dependent X‐ray diffraction indicates that this thermally stable interface effectively mitigates the anode phase transition from the original LiC6 to LiC12 state, resulting in a remarkable improvement in intrinsic safety and a 32% reduction in gas emission for battery. The 1.2 Ah NCM91|Gr pouch cell exhibits a thermal failure onset temperature as high as 183.1 °C and maintains stability at 180 °C for 60 min. Furthermore, a 360 Wh kg−1 12.3 Ah LiNi0.92Co0.06Mn0.02O2|graphite@20% silicon dioxide cell experiences no thermal runaway even at 200 °C. The 1.2 Ah NCM91|Gr pouch cell also delivers outstanding capacity retention of 90.5% after 1200 cycles with enhanced electrochemical performance. This study provides a promising approach for developing safer energy‐dense batteries through electrolyte and interface design. [ABSTRACT FROM AUTHOR]

Published
2024
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3. Hybrid capacitors utilizing halogen-based redox reactions at interface between carbon positive electrode and aqueous electrolytes

Author

Yuka Murakumo, Masashi Ishikawa, Masashi Naitou, Masaki Yamagata, Shigeaki Yamazaki, Tatsuya Ito, and Shimooka Toshiharu

Subjects
Working electrode, Standard hydrogen electrode, Renewable Energy, Sustainability and the Environment, Chemistry, Inorganic chemistry, Energy Engineering and Power Technology, 02 engineering and technology, Electrolyte, 010402 general chemistry, 021001 nanoscience & nanotechnology, Electrochemistry, 01 natural sciences, Reference electrode, Redox, Half-cell, 0104 chemical sciences, Electrode, Electrical and Electronic Engineering, Physical and Theoretical Chemistry, 0210 nano-technology
Abstract

We propose novel hybrid capacitors (HCs) with electrolyte-involved redox reactions of bromide or iodide species by pretreatment of an activated carbon positive electrode. The treatment is simple; impregnation of pores at an activated carbon fiber cloth (ACFC) as a positive electrode with bromine- or iodine-containing water before cell assembly. The treated positive electrode is applied to a HC cell with a non-treated negative electrode of ACFC and its electrochemical performance is investigated by galvanostatic cycling and leakage current tests. Few studies on such “electrolytic” charge storage systems have provided acceptable capacitor performance because of inevitable self-discharge caused by diffusion of charged species form an electrode to the other one through an electrolyte. Nevertheless, our electrolyte-redox-based HCs show excellent performance without undesirable diffusion of charged species. Moreover, the present HC utilizing a bromide redox system fulfills a practical cell voltage of 1.8 V in spite of an aqueous electrolyte system. This high voltage provides excellent energy density, which is 5 times higher than that in a conventional aqueous electric double-layer capacitor (EDLC), and 1.2 times higher even than that in a 2.7 V-class non-aqueous EDLC, while keeping high charge–discharge rate capability.

Published
2016
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4. Capacitance Enhancement of Aqueous EDLC Systems by Electrochemical Treatment

Author

Yoshiharu Matsuda, Hisao Teraishi, Masashi Ishikawa, Shigeaki Yamazaki, Tatsuya Sugimoto, Shimooka Toshiharu, Yasutaka Nagao, Tetsuya Jyozuka, and Hirokazu Oda

Subjects
Materials science, Aqueous solution, Electrode, Inorganic chemistry, Electrochemistry, Electrolyte, Electric double-layer capacitor, Capacitance, Low voltage, Voltage
Abstract

The electrochemical treatment of activated carbon electrodes has been investigated as a novel method enhancing the capacitance of electric double layer capacitor (EDLC) electrodes. The treatment at 0.7 V floating in a week at 70°C can be applied to EDLC with aqueous electrolytes. In 30 wt% H2SO4/H2O electrolyte, the treatment causes a capacitance increase in a low voltage region: 0–0.4 V. On the other hand, in 3.5 M NaBr/H2O electrolyte, it results in a remarkable capacitance increase of 2.4 times in a high voltage region: 0.4–1.0 V. These results suggest that the treatment mechanisms in the above electrolyte systems should be different. We report herein the origins and mechanisms of these capacitance increases.

Published
2007
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