Surface modification of lithium metal anode with lithium silicate-lithium phosphate composite layer for enhanced cycling stability

Abstract

Lithium metal anode with exceptionally high capacity is very attractive for next-generation anode material of lithium rechargeable batteries, but the safety problems and low Coulombic efficiency have retarded its commercialization. Despite the enormous efforts made to solve the problem of lithium metal anode, its practical use still appears to have a long way to go. In this study, to expedite the problem-solving, we suggest the use of a lithium silicate-lithium phosphate (SP) composite layer to suppress the dendritic growth of lithium and the formation of dead lithium. The composite layer is formed by simply dipping lithium metal in a mixed solution of tetraethyl orthosilicate and phosphoric acid. The synergistic effect of lithium silicate and lithium phosphate – high Li-ion conductivity and high Young's modulus of the inorganic layer – results in enhanced cycling stability of Li || Li symmetric cell and LiFePO4 || Li cell. The change in morphology of the lithium metal anode surface after cycling confirms that the SP layer mitigates the excessive dendritic growth of lithium and dead lithium formation, stabilizing the interface of lithium metal anode/electrolyte.