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 Li6.4La3Zr1.4Ta0.6O12 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 LiFePO4 (LFP)/Li solid‐state cells with PAN‐based SPEs. Moreover, the LFP/Li and LiNi0.8Co0.1Co0.1O2/Graphite pouch batteries both present good cycling and safety performances. This strategy provides new insights into designing high‐performance PAN‐based SPE for SSLMBs.