Rational design of graphitic-inorganic Bi-layer artificial SEI for stable lithium metal anode

Lithium metal batteries (LMBs) have attracted increasing attentions for their ultrahigh specific capacity (3860 mAh g−1) and the lowest electrode potential (−3.04 V vs. standard hydrogen electrode). However, the dynamic volume changes, the complex interfacial reactions, and the dendrite growth remain as the grand challenges in LMBs that prevent their practical applications. A bi-layer artificial solid electrolyte interphase (BL-SEI), which is composed of covalent graphitic materials (graphene and h-BN) and inorganic components (LiF, Li2O, Li3N, and Li2CO3), is rationally designed through comprehensive first-principles calculation to render a stable Li metal anode. Key interfacial properties, such as chemical stability, ionic conductivity, and mechanical strength, are systematically investigated to achieve a rational design of the BL-SEI. Among all the considered BL-SEI, the graphene/LiF combination is hopeful to exhibit the best interfacial stability and electrochemical performance. The protective role of BL-SEI for Li metal anode comes from the coupled effects through the anisotropic character and the defective structure. This work reveals the origin of the significant role of BL-SEI for achieving a stable Li metal anode from the atomic and electronic level, affording a paradigm for rational deign of a high-performance artificial SEI in working LMBs.