Elucidation of Reaction Mechanism of Silicon-Based Negative Electrode for Next-Generation Lithium-Ion Batteries

2018 Fiscal Year Final Research Report

• Project/Area Number: 17K17888
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Inorganic industrial materials; Device related chemistry
• Research Institution: Tottori University
• Principal Investigator: DOMI Yasuhiro 鳥取大学, 工学研究科, 助教 (50576717)
• Research Collaborator: SAKAGUCHI Hiroki ; USUI Hiroyuki
• Project Period (FY): 2017-04-01 – 2019-03-31
• Keywords: リチウム二次電池 / ケイ素系負極 / 電極ー電解質界面 / 反応挙動 / イオン液体電解液 / ガスデポジション法

Outline of Final Research Achievements

Elemental Si has a high theoretical capacity and has attracted attention as an anode material for high energy density lithium-ion batteries. Rapid capacity fading is the main problem with Si-based electrodes; this is mainly because of a massive volume change in Si during lithiation－delithiation. Here, we report that combining an ionic-liquid electrolyte with a charge capacity limit significantly suppresses Si volume expansion, improving the cycle life. We also establish a method of analysis to Li concentration in Si phase using soft-X-ray emission spectroscopy.
Some silicide electrodes maintain a high discharge capacity in an ionic-liquid electrolyte, whereas they show poor cycling performance in an organic electrolyte. The superior performance results from the high affinity for the transition metal that composes the silicide with Li. The obtained results will provide significant insights into novel alloy-based active materials for negative-electrode in lithium-ion batteries.

Free Research Field

電気化学

Academic Significance and Societal Importance of the Research Achievements

本研究においてリチウム二次電池用Si系負極の大きな課題であった体積膨張の抑制方法を見出し，そのメカニズムを明らかにした点は学術的に大変意義深いことである．このような研究成果によりSi系負極を実装した高エネルギー密度，長寿命および高安全性を兼ね備えたリチウム二次電池の実用化が近づいた．高性能な蓄電池は電気自動車の駆動用電源や再生可能エネルギーを貯蔵するための定地用電源として利用されることから，持続可能な社会の構築に向けて大きく貢献する．