Asymmetry and optimization of charge-discharge reaction for rechargeable Li ion battery

2019 Fiscal Year Final Research Report

• Project/Area Number: 18K19129
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 36:Inorganic materials chemistry, energy-related chemistry, and related fields
• Research Institution: Nagoya Institute of Technology
• Principal Investigator: Nakayama Masanobu 名古屋工業大学, 工学(系)研究科(研究院), 教授 (10401530)
• Project Period (FY): 2018-06-29 – 2020-03-31
• Keywords: ラプラス変換インピーダンス法 / 充放電非対称性 / リチウムイオン電池 / Li金属電極 / 抵抗解析 / 脱溶媒和抵抗

Outline of Final Research Achievements

In this research, we suggest design principles for the optimization of electrode reaction by separating charge/discharge polarization using Laplace transform impedance (LTI). In particular, the desolvation resistance of the Li metal electrode, which is strongly related to the inhibition of Li dendrite formation, is investigated by applying a LTI technique. The analysis revealed asymmetry in the desolvation/solvation resistances of Li metal electrodes. The desolvation resistances, which supposedly require large amounts of energy derived from the strong interaction between Li+ ion and solvents, were smaller than the solvation resistances. It has also been revealed that the larger resistance in the desolvation process is effective for suppressing Li dendrite formation further.

Free Research Field

無機固体化学、固体イオニクス

Academic Significance and Societal Importance of the Research Achievements

環境・エネルギー問題の解決に結びつく高性能蓄電池の製作のために、これまでほとんど研究の行われてて来なかった、充電と放電の抵抗分離を実施した。実用電池に用いられている LiMn2O4正極材料や、次世代電池の候補である金属リチウム負極材料に対して、特に検証を行った。特にリチウム金属負極では、これまで直感的に脱溶媒和反応が律速と考えられてきたが、今回の測定では逆反応の溶媒和反応が律速となることが示された。以上から、金属リチウム負極の利用には脱溶媒和抵抗の増加と溶媒和抵抗の減少という非対称な反応制御をする指針を得ることができた。