Design of High-Voltage Stable Hybrid Electrolyte with an Ultrahigh Li Transference Number

• Published in: ACS energy letters 2021-03
• Main Authors: Liu, Kewei, Li, Xiang, Cai, Jiyu, Yang, Zhenzhen, Chen, Zonghai, Key, Baris, Zhang, Zhengcheng, Dzwiniel, Trevor L., Liao, Chen
• Format: Article
• Language: English
• Subjects: ceramic; composite; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; polymer; single ion conducting; solid state electrolyte
• ISSN: 2380-8195; 2380-8195

Considering the high energy consumption during processing, and the low compliance and adhesion of ceramic electrolytes, the integration of polymer into ceramic electrolytes provides a way to mitigate the interfacial issues. However, the severe ion concentration gradient, low ionic conductivity, and instability toward Li metal and high-voltage cathodes become the major concerns in applying hybrid electrolytes. In this work, we report a single-ionconducting hybrid electrolyte (SIE-LLZO) with 64 wt % Li7La3Zr2O12(LLZO) particles embedded in a fluoroboron-centered Li-conductive polymer framework (LiBFSIE). The SIE-LLZO electrolyte exhibited a high Li transference number of 0.94 and electrochemical stability up to 5.6 V vs Li/Li+. Promising averaged Coulombic efficiencies of 99.97% and 99.91% were achieved in cells with LiNi0.8Co0.15Al0.05O2 and LiNi0.6Mn0.2Co0.2O2 cathodes for 400 and 200 cycles, respectively. Finally, the Li-conducting pathway in the hybrid electrolyte was further investigated by a 6Li-to-7Li isotope replacement method, indicating that Li transport mainly relies on the LLZO and interface between LiBFSIE and LLZO.