Polar polymer-solvent interaction derived favorable interphase for stable lithium metal batteries

Lithium metal has long been regarded as one of the most promising anode materials for future rechargeable batteries. However, the severe reaction of Li with carbonate electrolytes and the rapid growth of Li-dendrites at high current densities hinder its practical application in Li-metal batteries. Here we report a polar polymer protective layer to suppress highly corrosive cyclic carbonates by tuning polymer-solvent interactions. The CN groups of polyacrylonitrile (PAN) polymer chains in the polar polymer network can effectively reduce high reactivity of the CO groups of carbonate solvents leading to a stable solid electrolyte interphase (SEI) layer with higher inorganic components. In situ optical and electron microscopes demonstrate that the polar polymer network effectively restrained the formation and growth of Li-dendrites, which helps to stabilize the plating/stripping behavior of Li in a symmetric Li Li cell and a Li LiNi_1/3Co_1/3Mn_1/3O₂ cell. This study provides a useful perspective of controlling electrolyte coordination to form a stable SEI layer in carbonate electrolytes for Li-metal batteries.