Ionic liquid-containing cathodes empowering ceramic solid electrolytes

Eric Jianfeng Cheng; Mao Shoji; Takeshi Abe; Kiyoshi Kanamura

doi:10.1016/j.isci.2022.103896

Ionic liquid-containing cathodes empowering ceramic solid electrolytes

iScience. 2022 Feb 11;25(3):103896. doi: 10.1016/j.isci.2022.103896. eCollection 2022 Mar 18.

Authors

Eric Jianfeng Cheng^{1

2}, Mao Shoji², Takeshi Abe¹, Kiyoshi Kanamura²

Affiliations

¹ Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.
² Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, Tokyo 192-0397, Japan.

Abstract

Although ceramic solid electrolytes, such as Li₇La₃Zr₂O₁₂ (LLZO), are promising candidates to replace conventional liquid electrolytes for developing safe and high-energy-density solid-state Li-metal batteries, the large interfacial resistance between cathodes and ceramic solid electrolytes severely limits their practical application. Here we developed an ionic liquid (IL)-containing while nonfluidic quasi-solid-state LiCoO₂ (LCO) composite cathode, which can maintain good contact with an Al-doped LLZO (Al-LLZO) ceramic electrolyte. Accordingly the interfacial resistance between LCO and Al-LLZO was significantly decreased. Quasi-solid-state LCO/Al-LLZO/Li cells demonstrated relatively high capacity retention of about 80% after 100 cycles at 60°C. The capacity decay was mainly because of the instability of the IL. Nevertheless, the IL-containing LCO cathode enabled the use of Al-LLZO as a solid electrolyte in a simple and practical way. Identifying a suitable IL is critical for the development of quasi-solid-state Li-metal batteries with a ceramic solid electrolyte.

Keywords: Ceramics; Energy storage; Materials science.