Lithium metal anode is regarded as an attractive option for next-generation high-energy-density rechargeable batteries. However, the unstable solid-electrolyte interphases between lithium anode and electrolyte lead to uncontrolled growth of lithium dendrites. Herein, we describe the surface reconstruction of Li anode by molecular beam epitaxy deposition of an ultrathin and compact bismuth film. During Li plating process, the electrochemical active bismuth film is prone to form a close-knit lithiophilic lithium-bismuthide (Li_xBi) alloy layer through electrochemical alloying with lithium metal. Benefiting from its high ionic conductivity, lithiophilic characteristics, high chemical stability, good mechanical properties and air/moisture tolerance, the Li_xBi-rich layer efficiently inhibit the parasitic reactions between Li anode and electrolyte, and thus favor a dendrite-free Li plating/stripping process, as verified by electrochemical tests and in-depth analyses. Symmetric cells with Bi-coated Li electrodes show a stable and dendrite-free cycling behavior at 1.0 mAh cm⁻² for 300 h and superior rate performance up to 5.0 mA cm⁻². When Bi-coated lithium anodes are paired with a LiNi_0.5Co_0.2Mn_0.3O₂ cathode, a stable cycling life for over 300 cycles at 0.5C with a high capacity retention rate of 97% is obtained. This work provides new insights and strategies for the construction of Li-rich alloy layers on lithium metal surface via molecular beam epitaxy that enables dendrite-free and high-performance lithium metal batteries.

金属锂阳极被认为是下一代高能量密度可充电电池的有吸引力的选择。然而，锂阳极和电解质之间不稳定的固体电解质中间相导致锂树枝状晶体的不受控制的生长。在这里，我们描述了通过超薄而紧凑的铋膜的分子束外延沉积对锂阳极进行表面重构。在锂电镀过程中，电化学活性铋膜易于与锂金属发生电化学合金化，从而形成紧密编织的亲硫锂-铋锂（Li _x Bi）合金层。得益于其高离子电导率，亲硫性，高化学稳定性，良好的机械性能和耐空气/潮气性，Li _x富铋层有效地抑制了锂阳极与电解质之间的寄生反应，因此有利于无枝晶的锂电镀/剥离工艺，这已通过电化学测试和深入分析证实。带有Bi涂层Li电极的对称电池在1.0 mAh cm ^{- 2的条件下}持续300 h表现出稳定且无枝晶的循环行为，在高达5.0 mA cm ^{-2的条件下}具有出色的倍率性能。当双涂层锂阳极与LiNi _0.5 Co _0.2 Mn _0.3 O ₂配对时阴极，在0.5C时可获得300次以上循环的稳定循环寿命，且容量保持率高达97％。这项工作为通过分子束外延在锂金属表面上构建富锂合金层提供了新的见识和策略，这种分子束外延使无枝晶的高性能锂金属电池成为可能。