Mesoporous Co₃O₄-Modified Gel Polymer Electrolyte Applied in Lithium–Sulfur Batteries

The exploration of high-performance solid-state electrolytes is critical for the development of lithium–sulfur (Li–S) batteries. Herein, a high-performance hybrid gel polymer electrolyte (GPE) is prepared by introduction of mesoporous Co3O4 (m-Co3O4) particles into the poly(vinylidene fluoride-hexafluoropropylene) (PVDF–HFP) membrane containing electrolyte. As an inorganic filler, m-Co3O4 has a large specific surface area, polar surface, and ordered pore channels, which can strongly capture soluble lithium polysulfides and suppress the shuttle effect. Moreover, the introduced m-Co3O4 particles can interact with the PVDF–HFP membrane to reduce its crystallinity as well as improve its pore structure and ion mobility. Thus, the hybrid GPE achieves an ionic conductivity of 3.23 × 10–3 S cm–1 at room temperature, and meanwhile, its thermal decomposition temperature and electrochemical stability window reach 482 °C and 4.70 V, respectively. The Li–S cell assembled with the hybrid GPE exhibits better cycle and rate performance than the Li–S cell assembled with pure PVDF–HFP-based GPE. This modification strategy can effectively improve the performance of GPE and extend the application of GPE in Li–S batteries.