Liquid metal as an efficient protective layer for lithium metal anodes in all‐solid‐state batteries

Abstract Lithium metal batteries with inorganic solid‐state electrolytes have emerged as strong and attractive candidates for electrochemical energy storage devices because of their high‐energy content and safety. Nonetheless, inherent challenges of deleterious lithium dendrite growth and poor interfacial stability hinder their commercial application. Herein, we report a liquid metal‐coated lithium metal (LM@Li) anode strategy to improve the contact between lithium metal and a Li₆PS₅Cl inorganic electrolyte. The LM@Li symmetric cell shows over 1000 h of stable lithium plating/stripping cycles at 2 mA cm⁻² and a significantly higher critical current density of 9.8 mA cm⁻² at 25°C. In addition, a full battery assembled with a high‐capacity composite LiNbO₃@LiNi_0.7Co_0.2Mn_0.1O₂ (LNO@NCM721) cathode shows stable cycling performance. Experimental and computational results have demonstrated that dendrite growth tolerance and physical contact in solid‐state batteries can be reinforced by using LM interlayers for interfacial modification.