Lithium metal is a highly desirable anode for lithium rechargeable batteries, having the highest theoretical specific capacity and lowest electrochemical potential of all material candidates. Its most notable problem is dendritic growth upon Li plating, which is a major safety concern and exacerbates reactivity with the electrolyte. Here we report that Li-rich composite alloy films synthesized in situ on lithium by a simple and low-cost methodology effectively prevent dendrite growth. This is attributed to the synergy of fast lithium ion migration through Li-rich ion conductive alloys coupled with an electronically insulating surface component. The protected lithium is stabilized to sustain electrodeposition over 700 cycles (1,400 h) of repeated plating/stripping at a practical current density of 2 mA cm⁻² and a 1,500 cycle-life is realized for a cell paired with a Li₄Ti₅O₁₂ positive electrode. These findings open up a promising avenue to stabilize lithium metal with surface layers having targeted properties.

锂金属是锂可再充电电池非常需要的阳极，在所有候选材料中具有最高的理论比容量和最低的电化学势。其最显着的问题是锂电镀后的树枝状生长，这是一个主要的安全隐患，并加剧了与电解质的反应性。在这里，我们报道通过一种简单且低成本的方法在锂上原位合成的富锂复合合金膜有效地防止了枝晶生长。这归因于快速锂离子迁移通过富锂离子导电合金与电子绝缘表面成分耦合的协同作用。受保护的锂稳定下来，以2 mA cm的实际电流密度重复电镀/剥离700次循环（1,400小时），以维持电沉积对于与Li ₄ Ti ₅ O ₁₂正极配对的电池，可实现^-2的循环寿命和1,500的循环寿命。这些发现为用具有目标性能的表面层稳定锂金属开辟了一条有希望的途径。