Dendrite-free Li-metal anode via a dual-function protective interphase layer for stable Li-metal pouch cell

Abstract

The formation of unstable solid electrolyte interphase (SEI) and the breed of continuous Li dendrites/dead Li deteriorate the cycling performances of Li-metal batteries (LMBs), which restricts its practical application and leads to severe safety hazards. Artificial SEI is widely considered as a facile and feasible approach to address these issues. Herein, a dual-function protective interphase (DFPI) is innovatively designed via an indium fluoride (InF3)-polyvinylidene difluoride (PVDF) coating layer on Li-metal anode (LMA). Precisely, the InF3-PVDF artificial SEI in situ forms a lithium fluoride (LiF)-rich PVDF-based SEI and lithium-indium (Li-In) alloy substrate during plating process. The Li-In alloy is lithiophilic, which promotes the growth of transverse ellipses of plating Li; the electronically insulated LiF/PVDF composited SEI has fine mechanical flexibility, which adapts to the volumetric expansion by Li deposition and guarantees stable Li-ion migration process. Therefore, thanks to this dual-function collaborative mechanism, a dendrite-free LMA is successfully constructed. As a result, the robust LMA endows Li||LiFePO4 pouch cell and Li||S pouch cell stable cycling performances under practical conditions. This work thus opens a new avenue for designing multifunctional artificial SEI to stabilize alkali-metal anode for promising alkali-metal batteries.