Superionic Conductivity Invoked by Enhanced Correlation Migration in Lithium Halides Solid Electrolytes
Rui Li, Pushun Lu, Xinmiao Liang, Liwei Liu, Maxim Avdeev, Zhi Deng, Shuai Li, Kaiqi Xu, Jiwen Feng, Rui Si, Fan Wu, Zhizhen Zhang, Yong‐Sheng Hu
Abstract
Lithium halides are experiencing reflorescence as a promising solid electrolyte in all-solid-state batteries (ASSBs) owing to their moderate conductivities and high oxidation potential. Herein we report new lithium-superionic chlorides, Li 3– x Sc 1– x Zr x Cl 6 and Li 3– x Sc 1– x Hf x Cl 6 ( x = 0.25, 0.50, 0.625, 0.75), that demonstrate high ionic conductivities up to 2.2 mS cm –1 at room temperature coupled with low activation energy barriers (0.31 and 0.33 eV for Zr and Hf-analogy, respectively). This notably improved conductivity upon Zr 4+ /Hf 4+ substitution is ascribed to the decreased energy barrier along the c axis and enhanced correlated migration invoked by the tuned Li + /vacancy concentration. Evaluation in solid-state cells further confirmed the potential of this electrolyte to be used in high voltage ASSBs. Our work elucidates the impact of tuned cationic/vacancy concentration and consequently enhanced correlated migration on cationic conductivity. This strategy can be extended to other systems and serve as a guideline for the design of fast ion conductors.