Ionic liquid-containing cathodes empowering ceramic solid electrolytes

• Published in: iScience 2022-03, Vol.25 (3), p.103896-103896, Article 103896
• Main Authors: Cheng, Eric Jianfeng, Shoji, Mao, Abe, Takeshi, Kanamura, Kiyoshi
• Format: Article
• Language: English
• Subjects: Ceramics; Energy storage; Materials science
• ISSN: 2589-0042; 2589-0042
• DOI: 10.1016/j.isci.2022.103896

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. [Display omitted] •An ionic liquid (IL)-containing quasi-solid-state LiCoO2 (LCO) cathode was developed•Quasi-solid-state LCO/Al-doped Li7La3Zr2O12/Li cell showed high capacity retention•Optimal IL content in the quasi-solid-state LCO cathode was about 11 wt%•Battery capacity degradation was mainly due to the instability of the IL Energy storage; Materials science; Ceramics