Identifying the positive role of lithium hydride in stabilizing Li metal anodes.

Lithium hydride has been widely identified as the major component of the solid-electrolyte interphase of Li metal batteries (LMBs), but is often regarded as being detrimental to the stabilization of LMBs. Here, we identify the positive and important role of LiH in promoting fast diffusion of Li ions by building a unique three-dimensional (3D) Li metal anode composed of LiMg alloys uniformly confined into graphene-supported LiH nanoparticles. The built-in electric field at the interface between LiH with high Li ion conductivity and LiMg alloys effectively boosts Li diffusion kinetics toward favorable Li plating into lithiophilic LiMg alloys through the surface of LiH. Therefore, the diffusion coefficient of Li ions of the thus-formed 3D structured Li metal anode is 10 times higher than the identical anode without the presence of LiH, and it exhibits a long cycle life of over 1200 hours at 3 mA cm -2 under 5 mA hour cm -2 .