Li–Bi and Li–In alloys-based composite anode for lithium metal batteries

Lithium (Li) metal anode for high-energy-density secondary batteries has gained increasing attention in recent years due to its ultra-high specific capacity and the lowest redox potential. However, the Li anode suffers from severe issues including dimensional instability, Li dendrite growth, and low Coulombic efficiency (CE). In this work, a composite Li electrode (Li–Bi–In) with lithium–bismuth (Li–Bi) and lithium–indium alloys (Li–In) as the lithium host is fabricated to address the dimensional instability of the Li anodes. During Li stripping from the electrode, a porous structure composed of Li3Bi and Li13In3 alloys is formed and sustains the structural integrity. During Li plating, the Li3Bi alloy with high Young's modulus keeps stable, while the Li13In3 alloy with high lithiophilicity and ionic conductivity facilitates Li nucleation and uniform Li plating. Because of the synergistic effect of the two alloys, Li–Bi–In shows remarkable electrochemical performance. The symmetrical cell can stably cycle for more than 1200 h at a high current density of 5 mA cm−2. A full cell with Li–Bi–In anode and Li4Ti5O12 cathode stably runs for 200 cycles. This work provides a facile and effective strategy for fabricating lithium alloy-based composite anodes for lithium metal secondary batteries.