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

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. Graphic abstract