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

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%.