Artificial Solid‐Electrolyte Interphase for Lithium Metal Batteries

Abstract Li metal has attracted intense attention due to its high specific capacity, but the dendrite growth during cycling impedes its practical application as a rechargeable anode. To improve the stability of the solid‐electrolyte interphase (SEI) on Li metal is the key to develop Li anode with high safety. In native SEI, inorganics act as fast ion channels and organics play the role of soft base with high flexibility to buffer volume change. However, the SEI with inorganics close to Li surface and organics close to electrolyte always leads to a fragile structure, resulting in repeatedly breaking and growing of the surface layer. Artificial SEI is one of the most effective ways to improve interphase stability and extend the cycle life of Li anode. Inorganics such as Li fluoride, Li nitride, Li phosphate and Li alloys have been widely applied in Li protection. In situ chemical reactions, spin coating and doctor blade coating of organics were also conducted to obtain SEI with high lithiophilic functional groups and high elasticity. To fabricate an ideal artificial SEI, organic and inorganic components should be rearranged as a rational structure to possess synergetic effects with both high flexibility and ionic conductivity. This Minireview summarizes the most recent works on artificial SEI and discusses the electrochemical performance of different components as interphase, aiming to inspire the study on designing and fabricating stable Li anode with robust interphase structure.