In-depth understanding of the silicon lithiation process for next-generation lithium secondary batteries

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K05649
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 36010:Inorganic compounds and inorganic materials chemistry-related
• Research Institution: Tottori University
• Principal Investigator: Domi Yasuhiro 鳥取大学, 工学研究科, 准教授 (50576717)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: リチウム二次電池 / 負極 / ケイ素 / リンドープ / シリサイド / コンポジット化 / イオン液体

Outline of Final Research Achievements

We thoroughly investigated the mechanism of performance improvement or degradation of Si-based negative electrodes by various analytical methods. In the P-doped Si electrode, which showed good performance, the Li concentration distribution in the Si layer was homogeneous, whereas the Li-Si alloy phase with a large expansion rate was heterogeneously distributed in the Si-alone electrode that deteriorated early. Heterogeneous distribution of the phase caused a local accumulation of high strain and a drastic increment in the thickness of the Si layer, which led to capacity decay. The above results were obtained based on a Si-specific analysis method originally developed in this study. Additionally, the reaction behavior of the silicide electrode and silicide/Si composite electrode was clarified, and based on the obtained knowledge, materials were successfully fabricated to obtain good performance.

Free Research Field

無機材料化学

Academic Significance and Societal Importance of the Research Achievements

本研究ではリチウム二次電池用Si系負極の反応挙動を徹底解明した．得られた成果に基づき新たな材料設計指針も得られており，一部については実証した．これまで推測の域を超えなかったことを実験事実に基づいて立証した点は学術的に大変意義深い．本研究成果は高エネルギー密度，長寿命，高い安全性および高速充放電性能を兼ね備えた高性能リチウム二次電池を構築するうえで大変重要であり，脱炭素社会の実現に向けて大きく貢献する．