Circumferential Li metal deposition at high rates enabled by the synergistic effect of a lithiophilic and ionic conductive network

Abstract

Combining Li-metal anodes with high-energy cathodes can hopefully produce high-energy-density batteries (∼500 W h kg⁻¹). However, practical applications of Li-metal anodes are limited by irregular Li growth, which leads to a short cycling life and serious security risks. Herein, we report a flexible network consisting of Li_0.33La_0.56TiO₃/carbon nanowires coated with an Au layer (LLTO/C@Au) to work as a Li metal host. The LLTO nanocrystals encapsulated in carbon increase the Li ion conductivity and flexibility of the network. Moreover, the lithiophilic Au layer leads to a feasible and homogeneous Li metal deposition at the surface, which further boosts the Li ion migration in the nanowires. As a result, the diffusion coefficient of the lithiophilic and ionic conductive network (LLTO/C@Au) is much higher than that of the only ionic conductive network (LLTO/C) and the only lithiophilic network (C@Au). Such synergistic effects of the lithiophilic and ionic conductive network on simultaneously optimizing the nucleation, transportation, and accumulation of Li enable circumferential Li metal plating/stripping at high rates. The LLTO/C@Au–Li symmetrical cell can run at a high rate of 20 mA cm⁻² for 150 cycles with a capacity of 2 mA h cm⁻² and at a rate of 2 mA cm⁻² for 500 h with a large capacity of 10 mA h cm⁻². This work sheds light on the synergistic mechanism of a lithiophilic and ionic conductive network on the Li metal deposition, which offers a new perspective for designing advanced Li-metal batteries with low negative/positive ratio.