Oxygen Vacancy‐Li<sub>2</sub>ZrO<sub>3</sub>: A New Choice for Boosting Homogenous Distribution and Transport of Lithium Ion in Composite Solid‐State Electrolytes
Yanru Wang, Timing Fang, Chao Wang, Siyu Wang, Ke Yang, Jie Biao, Daohao Li, Dongjiang Yang, Yan‐Bing He, Yanzhi Xia
Abstract
Abstract The low concentration and inhomogenous distribution of free lithium ion (Li + ) in composite polymer electrolytes (CPEs) greatly restrict the Li + transport, cycle stability and rate performance of all solid‐state batteries. In this work, lithium zirconate with superficial oxygen (O)‐vacancies (O‐LZO) is reported as a new Li + conductors for polyethylene oxide (PEO)‐based CPEs (PEO@O‐LZO). The O‐LZO demonstrates exceptional Li + transport capability, and its superficial O‐vacancies efficiently adsorb anions to facilitate the dissociation of lithium salts, leading a high concentration of free Li + in CPEs. Furthermore, the electropositive equilibrium charge layer of O‐vacancies avoids the aggregation of Li + near the filler and achieves a stable interface to promote the efficient and continuous Li + transport. These effects contribute to a high Li + conductivity of 1.63 × 10 −4 S cm −1 and a Li + migration number of 0.35 for PEO@O‐LZO at 40 °C. The assembled battery (LiFePO 4 /PEO@O‐LZO/Li) exhibits a capacity of 120 mAh g −1 at 3 C and stable cycling performance with an 80.5% capacity retention after 800 cycles at 1 C and 40 °C, maintaining excellent coulombic efficiency. This work provides a design principle of fillers to regulate Li + concentration and distribution in CPEs for efficient solid‐state lithium metal batteries.