Oxygen vacancies with localized electrons direct a functionalized separator toward dendrite-free and high loading LiFePO₄ for lithium metal batteries

The pursuit of high energy density has promoted the development of high-performance lithium metal batteries (LMBs). However, the underestimated but non-negligible dendrites of Li anode have been observed to shorten battery lifespan. Herein, a composite separator (TiO2-x@PP), in which TiO2 with electron-localized oxygen vacancies (TiO2-x) is coated on a commercial PP separator, is fabricated to homogenize lithium ion transport and stabilize the lithium anode interface. With the utilization of TiO2-x@PP separators, the symmetric lithium metal battery displays enhanced cycle stability over 800 h under a high current density of 8 mA cm(-2). Moreover, the LMBs assembled with high-loading LiFePO4 (9.24 mg cm(-2)) deliver a stable cycling performance over 900 cycles at a rate of 0.5 C. Comprehensive theoretical studies based on density functional theory (DFT) further unveil the mechanism. The favorable TiO2-x is beneficial for facilitating fast Li+ migration and impeding anions transfer. In addressing the Li dendrite issues, the use of TiO2-x@PP separator potentially provides a facile and attractive strategy for designing well-performing LMBs, which are expected to meet the application requirements of rechargeable batteries. (C) 2022 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.