Polyphenylene sulfide quasi-solid-state electrolyte for limited Li metal battery

Abstract The urgent need for safe and high energy batteries is pushing the battery studies towards the solid-state direction, and the most central question is finding proper solid-state electrolyte. So far, the recently studied electrolyte systems have obvious advantages and fatal weaknesses, resulting in indecisive plans for industrial production. In this work, we propose a thin and dense lithiated polyphenylene sulfide (PPS)-based solid polymer electrolyte prepared by a solvent-free process in a pilot stage. Moreover, the PPS surface is functionalized to immobilize the anions, increase the Li ion transference number to 0.8-0.9, and widen the electrochemical potential window (>5.1 V). At room temperature, the PPS-based quasi-solid electrolyte (PPS-QSSE) exhibits high intrinsic Li+ diffusion coefficient and ionic conductivity (>10-4 S cm-1), excellent thermal stability, and Li+ transport rectifying effect, resulting in homogenous Li-plating on Cu at high current density. Based on the limited Li-plated Cu anode or anode-free Cu, high loadings cathode and high voltage, the Li metal batteries with PPS-QSSEs deliver high energy density (>1000 Wh L-1) and good cycling at high power (900 W L-1) exceeding that of state-of-the-art Li-ion batteries. The results enlighten the mechanism of solid-liquid two phase conduction and promote the solid-state battery towards practicality.