Single-Crystalline LiMg Alloy Anode for Deep Cycling All Solid State Lithium Metal Batteries

Abstract

All solid state lithium metal batteries (ASSLMBs) with enhanced energy density has driven the exploration of Li-alloy anodes such as Li-Mg alloy owing to its solid-solution structure and high theoretical specific capacity. But the Li atom diffusion limitation on Li-Mg electrode surface further leads to sluggish atoms transport dynamics. Herein, single-crystalline (110)-oriented Li_0.9Mg_0.1 (denoted as LiMg(110)) anode is obtained by a tailored melt-annealing procedure to tackle the above issues. Theoretical analyses and experimental results demonstrate that the crystallographic structural (110) orientation of LiMg anode can facilitate Li atom diffusion and guarantee the electrode stability during deep cycling. As a result, the LiMg(110) electrode exhibits longer cycle life with lower overpotential than polycrystalline LiMg at high current densities and areal capacities in symmetric cells. A critical current density (CCD) at the forefront of 2.5 mA cm⁻² is achieved in Li₃InCl₆ (LIC) solid-state system. The ASSLMB with high areal capacity (3.8 mAh cm⁻²), high current density (0.76 mA cm⁻²), and low negative/positive capacity N/P ratio (2.14) achieves exceptional cyclability over 160 cycles. The outcomes highlight a promising crystallographic regulation strategy toward practical applications of high-performance lithium metal batteries.