Phase-Separation-Induced Porous Lithiophilic Polymer Coating for High-Efficiency Lithium Metal Batteries

Solid-electrolyte interphase (SEI) plays a pivotal role in stabilizing lithium (Li) metal anode for rechargeable batteries. However, electrolyte-derived SEI often suffers from poor stability, leading to Li dendrite growth, consumption of electrolyte, and short cycle life. Here, we report a porous lithiophilic polymer coating induced by phase separation of polyvinylidenefluoride–polyacrylonitrile (PVDF–PAN) blends for stabilizing Li metal anode. Different from single polymer coating, PVDF–PAN blends protective layer with porous structures caused by phase separation can provide effective Li+ transport channels and regulate uniform Li+ flux. The lithiophilic functional groups of C≡N and C–F can promote uniform Li deposition and accelerate Li+ diffusion at the same time during plating/stripping process. As a result, Li||NCM811 full cells using PVDF–PAN coated Li present an apparently improved cycling stability and higher Coulombic efficiency with lean electrolyte (7.5 μL mA h–1), limited Li supply (N/P ratio = 2.4), and high areal capacity (4.0 mA h cm–2).