Towards Ultra-Stable Lithium Metal Batteries: Interfacial Ion Flux Regulated through LiAl LDH-Modified Polypropylene Separator

Abstract Lithium metal batteries have attracted remarkable attention because of their high theoretic specific capacity and low redox potential. However, the issues, including uncontrollable dendritic formation and the highly reactive nature of Li anodes hinder the practical application of lithium metal batteries. Herein, LiAl layered double hydroxide (LiAl LDH) modified separators (LiAl LDH@PP) are prepared by simply coating [LiAl2(OH)6]Cl nanoflakes onto polypropylene (PP) membranes. LiAl LDH nanoflakes with plenty of octahedral vacancies and abundant lithium ion diffusion pathways improve the ionic conductivity, surface electrolyte wettability and mechanical robustness of the separators. The modified separator promotes the interfacial lithium ionic flux, suppressing the dendrite formation and consequently increasing the cycling stability of lithium metal batteries. Even at an ultrahigh current density of 20 mA cm−2, the Li|Li symmetric batteries with the LiAl LDH@PP separators can be charged/discharged for more than 3000 h, demonstrating the remarkably high cycling stability. This work provides a feasible and efficient strategy for enhancing the cycling performance and safety of lithium metal batteries.