Reactive Solid Polymer Layer: From a Single Fluoropolymer to Divergent Fluorinated Interface.

Controlling the structure and chemistry of solid electrolyte interphase (SEI) underpins the stability of electrolyte-electrode interface, and is crucial for advancing rechargeable lithium metal batteries (LMBs). Here, we utilized photo-controlled copolymerization to achieve the on-demand synthesis of fluorosulfonyl fluoropolymers as unprecedented artificial SEI layers on Li metal anodes. This work not only enables instant formation of a hybrid polymer-inorganic interphase that consists of a polymer-enriched top layer and a LiF-fortified bottom layer, originating from a single polymeric component, but also imparts various desirable physical properties (e.g., good mechanical strength and flexibility, high ion conductivity, low overpotential) to SEI via a single-to-divergent strategy. Model reactions and structural characterizations supported the formation of a divergent fluorinated interphase, which furnished prolonged stabilization of Li deposition, high coulombic efficiency and improved cycling behavior in electrochemical experiments. This work highlights the great potential of exploring reactive polymers as versatile coatings to stabilize Li metal anodes, providing a promising avenue to solve electrode-electrolyte interfacial problems for LMBs.