ZIF‐8‐functionalized polymer electrolyte with enhanced performance for high‐temperature solid‐state lithium metal batteries

Abstract Solid polymer electrolytes (SPEs) with high ionic conductivity are desirable for solid‐state lithium metal batteries (SSLMBs) to achieve enhanced safety and energy density. Incorporating nanofillers into a polymeric matrix to develop nanocomposite solid electrolytes (NCSEs) has become a promising method for improving the ionic conductivity of the SPEs. Here, a novel ZIF‐8‐functionalized NCSE was prepared for high‐temperature SSLMBs using an in situ radical polymerization method. It is found that the ZIF‐8 nanoparticles could reduce the crystallinity of polymer segments and offer a Lewis acid surface that promotes the dissociation of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and stabilizes the TFSI − anion movement. Thus, the as‐prepared NCSE exhibits an outstanding ionic conductivity of 1.63 × 10 –3 S·cm −1 , an electrochemical stability window of 5.0 V at 80 °C, and excellent interface compatibility with lithium metal anode with a stable polarization over 2000 h. Furthermore, the assembled SSLMBs with LiFePO 4 cathode show dendrite‐free Li‐metal surface, good rate capability, and stable cycling stability with a capacity retention of 70% over 1000 cycles at a high temperature of 80 °C. This work provides valuable insights into promoting the ionic conductivity of SPEs.