Lithium metal is a promising anode material for rechargeable batteries with high energy density. However, the uncontrollable dendrite growth severely hinders the commercialization of Li metal anode. Inspired by the “leveling” mechanism in traditional electroplating, we demonstrate that boron nitride nanosheets (BNNSs) as a liquid electrolyte additive can level out Li protrusions and enable dendrite-free Li metal anodes. 2D BNNSs can automatically and continuously flatten Li deposits and accommodate volume changes during Li plating/stripping. B atoms in BNNS as Lewis acid sites interact with Lewis basic anions in electrolyte, reducing Li⁺ concentration gradient and unifying Li deposition. The collect effects of BNNS additive give rise to dendrite-free Li anodes over 400 h and deep plating/stripping up to 35 mAh cm⁻², as well as potential application in sub-zero temperature batteries (−20 °C). Li–S full cells using BNNS electrolyte also exhibit improved performance. This simple and effective strategy is applicable to develop dendrite-free Li or other metal anodes in high-performance energy storage devices.

锂金属是具有高能量密度的可再充电电池的有希望的负极材料。然而，不可控的枝晶生长严重阻碍了锂金属阳极的商业化。受传统电镀中“流平”机制的启发，我们证明了氮化硼纳米片（BNNSs）作为液体电解质添加剂可以使Li突起平整，并形成无枝晶的Li金属阳极。2D BNNS可以自动连续地平整锂沉积物，并适应锂电镀/剥离过程中的体积变化。BNNS中的B原子作为路易斯酸位与电解质中的路易斯碱性阴离子相互作用，从而还原Li ⁺浓度梯度和统一的锂沉积。BNNS添加剂的集电效应可在400 h内形成无枝晶的Li阳极，并进行高达35 mAh cm ^-2的深层电镀/剥离，以及在零温度以下电池（-20°C）中的潜在应用。使用BNNS电解质的Li–S满电池也表现出改善的性能。这种简单有效的策略适用于开发高性能储能设备中的无枝晶锂或其他金属阳极。