Uniform Lithium Deposition Induced by Double Lithiophobic Sandwich Structure for Stable Lithium Metal Anode

The uncontrollable dendrite growth and complex interfacial reactions are still challenging issues hindering the practical applications of lithium (Li) metal anode. A variety of materials are widely studied to regulate the surface properties of Li metal anode except for the lithiophobic materials. This study shows that a double lithiophobic sandwich structure can induce uniform Li deposition to suppress Li dendrite growth at the nucleating stage. A hexagonal boron nitride (h-BN) particle layer on Cu foil (h-BN@Cu) is prepared as the research target to intensely explore the fundamental role of the lithiophobic h-BN layer on the diffusion and nucleation behavior of Li on the Cu surface. The h-BN layer makes the h-BN@Cu interface possess lower adsorption energy and more substantial charge transfer, leading to the "h-BN-Li-Cu" sandwich deposition mode. Theoretical calculations, in situ monitoring, and experimental tests confirm the relevance between uniform Li deposition and the h-BN@Cu interface structure. The h-BN@Cu anode enables a significantly improved lifespan (over 550 h) compared to the Cu anode and enhanced cycling stability when assembled in whole cells with LiFePO4 (LFP) cathode. This discovery provides a new insight into h-BN and other lithiophobic materials as a protective layer to improve the Li deposition behavior.