Electrolyte with boron nitride nanosheets as leveling agent towards dendrite-free lithium metal anodes

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.