Ring‐Opening Polymerization Reconfigures Polyacrylonitrile Network for Ultra Stable Solid‐State Lithium Metal Batteries

Abstract Polyacrylonitrile (PAN) is a promising polymer for solid‐state lithium (Li) metal batteries (SSLMBs). However, the low ionic conductivity of PAN‐based solid polymer electrolytes (SPEs) and unstable Li/PAN interface hinder the applications of PAN in SSLMBs. Herein, a strategy of ring‐opening polymerization is proposed to reconfigure the PAN‐based SPE network. Triggered by the alkaline species from Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 nanoparticles, ethylene carbonate (EC) undergoes nucleophilic ring‐opening reaction, and subsequently forms dipole–dipole interaction with the PAN chain. This polymerization process consequently reconfigures PAN segment, endowing the SPE with rapid Li + transport channels and enhanced interfacial stability with Li metal. As a result, the designed PAN‐based SPE demonstrates high ionic conductivity of 2.96 × 10 −4 S cm −1 and Li + transference number of 0.56 at 25 °C. The Li/Li symmetric cells with the reconfigured PAN network deliver a high critical current density of 1.8 mA cm −2 and maintain stable Li plating/stripping for 1200 h. A high‐capacity retention of 90.1% after 1000 cycles at 2 C is achieved in LiFePO 4 (LFP)/Li solid‐state cells with PAN‐based SPEs. Moreover, the LFP/Li and LiNi 0.8 Co 0.1 Co 0.1 O 2 /Graphite pouch batteries both present good cycling and safety performances. This strategy provides new insights into designing high‐performance PAN‐based SPE for SSLMBs.