Porous Composite Gel Polymer Electrolyte with Interfacial Transport Pathways for Flexible Quasi Solid Lithium-Ion Batteries

The growing demand for safer energy storage devices leads to wide research on solid-state lithium-ion batteries. However, as an important component in the solid-state battery, the solid-state electrolyte often encounters problems, especially the low conductivity at room temperature, inhibiting the development of solid-state batteries. Here, improved electrochemical performances of lithium-ion batteries are obtained by designing a composite gel polymer electrolyte with a sponge-like structure. The porous composite gel polymer electrolyte (PCGPE) is developed by a facile phase inversion process of poly(vinylidiene fluoride-hexafluoropropylene) (PVdF-HFP) and Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO). The solid-state nuclear magnetic resonance test proves the continuous porous structure constructs fast Li-ion transport pathways on internal interfaces. As a result, the ionic conductivity of PCGPE is up to 5.45 × 10^-4 S cm^-1 at room temperature. Moreover, an initial capacity of 142.2 mAh g^-1 and 82.6% capacity retention at 1 C after 350 cycles are successfully achieved in flexible LiFPO₄//PCGPE//Li batteries.