Dendrite‐Free Lithium‐Metal Batteries Enabled by 2D Lithophilic Conjugated Polymer on Separator

Abstract

Tacking issues of uncontrolled lithium dendrites formation with polymer‐based separator has a significant impact on the applications of lithium‐metal batteries. Here, porous poly(acrylonitrile) nanosheets (PPNS) enriched with conjugated C═C/C═N groups is designed on PP separator by spray‐coating. The conjugated molecular structure of PPNS affords high mechanical strength and thermal conductivity. Density functional theory (DFT) calculations confirm that polar N‐containing groups in PPNS derived from the cyclization of C≡N exhibit lithiophilic properties and effectively accelerate Li+ transport kinetics. Finite element simulation indicates PPNS with porous 2D nanosheet structure ensures a sufficient and uniform concentration of Li+ on the anode surface. Besides, a rich inorganic phase solid‐electrolyte interphase forms at the lithium metal interface under the induction of N‐containing groups, which further facilitates uniform lithium deposition. As a result, Li||LFP battery using PPNS@PP separator can stably cycle for 300 cycles at a high rate of 3C, with a capacity retention rate of 94.0%. Moreover, the Li||LFP pouch battery with PPNS@PP separator achieves steady cycling for 100 cycles at 0.2C, with a capacity retention rate of 95.7%.