Control of electrode interface and investigation of ion conductivity in Si negative electrodes with high energy densities for lithium-ion batteries

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H04649
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Energy engineering
• Research Institution: Doshisha University
• Principal Investigator: Haruta Masakazu 同志社大学, 研究開発推進機構, 准教授 (90580605)
• Research Collaborator: INABA Minoru ; DOI Takayuki
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 蓄電池 / リチウムイオン電池 / シリコン負極 / 表面被膜

Outline of Final Research Achievements

Improvement of cycle life of Si negative electrodes is necessary to apply to practical lithium-ion batteries with large capacities. An artificial surface layer was formed on Si film electrodes to inhibit reductive decomposition of an electrolyte, and its effects on electrochemical properties were investigated. The charge/discharge efficiency of the Si electrode was improved by coating with lithium fluoride (LiF). Changes in the surface morphology of the Si electrode with potential sweeping were investigated using in-situ AFM. Although large amount of surface deposits originating from electrolyte decomposition emerged on the bare-Si electrode, few surface deposits were observed on the LiF-coated Si electrode. It is clear that LiF is one important component of the surface layer to inhibit electrolyte decomposition on Si negative electrodes.

Free Research Field

エネルギー材料

Academic Significance and Societal Importance of the Research Achievements

従来の研究において、負極表面に自然形成した被膜が様々な手法により調べられてきたが、電池特性改善に有効な被膜成分についてはよく分かっていなかった。そこで、薄膜技術を用いて組成を制御した人工被膜を形成し、電気化学特性に与える影響を調べた。電解液分解を抑制する被膜成分の一つとしてフッ化リチウムが有効であることが明らかになり、Si負極の長寿命化につながると考えられる。人工被膜形成に関する知見を実用プロセスにフィードバックすることにより大容量蓄電池を実現し、省エネルギー社会の構築に貢献することが期待される。