Integration of Localized Electric-Field Redistribution and Interfacial Tin Nanocoating of Lithium Microparticles toward Long-Life Lithium Metal Batteries.

Lithium metal batteries (LMBs) have shown a huge prospect for next-generation energy storage devices, but are always plagued by the high reactivity of metallic Li and dendrite growth. Herein, we propose a strategy of localized electric field to achieve nondendritic and long-life LMBs. Li microparticles with conformal tin nanocoating (Sn@Li-MPs) are uniformly distributed in the hollow nitrogen-doped carbon shells/graphene host, in which each Sn@Li-MP works as a localized microelectric field, inducing even Li plating and stripping. Based on COMSOL simulation, the electric field relative intensity reaches the highest values at the gaps of neighboring Sn@Li-MPs. Therefore, Li+ ions are preferentially plated into the gaps to achieve smooth metallic Li. Additionally the interfacial nanosized Sn-Li alloy can effectively protect Sn@Li-MPs against parasitic reactions via reducing the contact with organic solvents. Attributed to these advantages, the symmetric Sn@Li-MPs battery displays a low overpotential of 0.32 V at a high current density of 10 mA cm-2 after 250 cycles. Coupled with the LiNi0.6Co0.2Mn0.2O2 layered cathode, the NCM622∥Sn@Li-MPs full battery exhibits an initial discharge capacity of 171.5 mA h g-1 at a 2 C discharge current rate and still retains 80.3% capacity after 949 cycles.