Li3Bi/LiF/Li2O derived from mechanical rolling of Li metal with BiOF nanoplates as stable filler for dendrite-free Li metal batteries

Abstract

Li is attractive anode for next-generation high-energy batteries. The high chemical activity, dendrite growth, and huge volume fluctuation of Li hinder its practical application. In this work, a Li–BiOF composite anode (LBOF) is obtained by combining Li metal with BiOF nanoplates through facile folding and mechanical cold rolling. Further, Li3Bi/LiF/Li2O filler is formed by the in-situ reactions of BiOF with contacted Li. In the filler, the Li3Bi, with high ionic conductivity and a lithiophilic nature, provides a mutually permeable channel for Li+ diffusion. The low surface diffusion energy barrier of Li3Bi and LiF can further promote the uniform deposition of Li. The conductive lithiophilic filler can reduce the local current density and provide a spatial limitation to the deposited Li. Consequently, the symmetrical LBOF||LBOF cell can cycle stably at 1 mA cm−2 for over 1300 h. Additionally, the surface of LBOF is flat with suppressed dendrite formation and free of dead Li accumulation, and the change in electrode volume is significantly alleviated. Furthermore, the LBOF||LiFePO4 full battery can maintain a stable cycle of more than 200 times with high capacity retention of 88.7% in a corrosive ester-based electrolyte. This simple mechanical approach is compatible with the current industrial route and is inspiring to solve the long-standing lithium-dendrite problem.