PVDF-HFP gel polymer electrolytes with a uniform porous network for lithium metal batteries

Modified poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP) exhibits excellent electrochemical stability and safety, making it one of the most promising gel polymer electrolytes (GPEs) for lithium metal batteries. To further optimize the performance of PVDF-HFP GPEs, N-formylmorpholine is used as a novel high-boiling nonsolvent for PVDF-HFP, and a uniform porous network rich in the β phase is prepared through a nonsolvent induced phase separation method. The optimized PVDF-HFP GPE (PNG10), enriched with the strongly polar β phase, can better promote the dissociation of lithium salts, while the uniform porous network provides the necessary conditions for the uniform distribution and conduction of ions, optimizing the electrode/electrolyte interface. As a result, the PNG10 GPEs achieves a simultaneous enhancement of ionic conductivity (1.32 × 10 −3  S cm −1 ) and lithium-ion transference number (0.82). Moreover, the Li|PNG10|LiFePO 4 cells demonstrate excellent long-term cycling stability and rate performance. The study highlights the importance of high-throughput porous network structures in the design of GPEs.