Polyphenylene Sulfide‐Based Solid‐State Separator for Limited Li Metal Battery

The urgent need for high energy batteries is pushing the battery studies toward the Li metal and solid-state direction, and the most central question is finding proper solid-state electrolyte (SSE). So far, the recently studied electrolytes have obvious advantages and fatal weaknesses, resulting in indecisive plans for industrial production. In this work, a thin and dense lithiated polyphenylene sulfide-based solid state separator (PPS-SSS) prepared by a solvent-free process in pilot stage is proposed. Moreover, the PPS surface is functionalized to immobilize the anions, increasing the Li+ transference number to 0.8-0.9, and widening the electrochemical potential window (EPW > 5.1 V). At 25 °C, the PPS-SSS exhibits high intrinsic Li+ diffusion coefficient and ionic conductivity (>10-4 S cm-1 ), and Li+ transport rectifying effect, resulting in homogenous Li-plating on Cu at 2 mA cm-2 density. Based on the limited Li-plated Cu anode or anode-free Cu, high loadings cathode and high voltage, the Li-metal batteries (LMBs) with polyethylene (PE) protected PPS-SSSs deliver high energy and power densities (>1000 Wh L-1 and 900 W L-1 ) with >200 cycling life and high safety, exceeding those of state-of-the-art Li-ion batteries. The results promote the Li metal battery toward practicality.