Investigation on the degradation phenomena at the surface of high-energy-density cathode materials of LIBs

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K15680
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 36020:Energy-related chemistry
• Research Institution: University of Hyogo
• Principal Investigator: Inamoto Junichi 兵庫県立大学, 工学研究科, 助教 (20816087)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: リチウムイオン電池 / 正極材料 / 劣化 / 表面

Outline of Final Research Achievements

In this study, to clarify the degradation mechanisms at surface region of high-energy-density cathode materials for LIBs, the degradation phenomena at the outmost surface of thin-film cathodes as model electrodes were analyzed. For LiNi0.5Mn1.5O4, stable passivation film was not formed on its surface, and it led to continuous oxidative decomposition of electrolyte solution and dissolution of transition metal ions. On the other hand, on the surface of Li-rich layered cathode material, stable and thick passivation surface film was formed on its surface. Since oxide anion in the material is oxidized and transforms into singlet oxygen, it was considered that chemical oxidation of electrolyte solution by the singlet oxygen together with electrochemical oxidation of it led to form the stable passivation film.

Free Research Field

電気化学

Academic Significance and Societal Importance of the Research Achievements

リチウムイオン電池は輸送機器や社会インフラに広く利用されており、エネルギーの利用効率向上だけでなく、さらなる長寿命化が必要とされている。本研究では高エネルギー密度が期待できる次世代リチウムイオン電池の正極材料の劣化要因を詳細に調べることで、その高エネルギー密度化と長寿命化を同時に達成するための重要な基礎的知見を提供するものである。今回の結果から、正極材料の劣化抑制に重要な因子を明らかにすることができたため、この知見を生かして次世代リチウムイオン電池の長寿命化に貢献できる。