A Solid-State Lithium Battery with PVDF–HFP-Modified Fireproof Ionogel Polymer Electrolyte

For solid-state lithium metal batteries (SSLBs), gel polymer electrolytes (GPEs) are of interest due to the special structural features that avoid contact problems at the solid–solid interface and reduce safety issues. However, the practical utilities are still unsatisfying due to the decomposition of conventional liquid electrolytes under high operating voltages and low ionic conductivity. Herein, we design a composite ionogel-in-MXene electrolyte (CIME) based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) codoped with monolayer MXene (Ti3C2Tx). The prepared CIME shows a 3D porous network with a great Li+ transference number of 0.67 and high room-temperature ionic conductivity (1.54 × 10–3 S cm–1). In addition, the lithium–metal symmetric batteries have excellent long-term lithium plating and stripping capability because the cells can maintain long cycle stability of 800 h. As a result, the LiFePO4|CIME|Li battery has a long-cycle capacity for 200 cycles at 30 °C, with 97.8% capacity retention at a rate of 0.2 C. Moreover, good flexibility, thermal stability, and flame retardancy are also achieved for this GPE, providing more thoughts for future applications of GPEs in solid-state lithium–metal batteries.