Efficient ion transport mode and stable Li⁺-interface induced by the introduction of HA-SiO₂ in PVDF-based...

Polyvinylidene fluoride (PVDF) materials have been widely investigated as polymer matrix for solid polymer electrolytes (SPEs) due to their high dielectric constant, electroactive effect (piezo-, pyro-, and ferroelectricity), and excellent thermal stability. However, the poor interface compatibility caused by highly reactive residual solvents and unsatisfactory ionic conductivity owing to sluggish Li⁺ transport kinetics are principal bottlenecks impeding the further development of PVDF-based electrolytes. Herein, we design a PVDF-based electrolytes with the assistance of hydrophilic-amorphous silica (HA-SiO₂). Result shows that HA-SiO₂ can tightly anchor reactive residual solvents on the surface due to its high adsorption energy with [Li(DMF)₃]⁺, which not only dramatically suppresses the severe side reactions between the electrolyte and Li anode, but also provides additional Li⁺-hopping sites on the surface of HA-SiO₂. Meanwhile, the anchored [Li(DMF)₃]⁺ snatch away partial Li⁺ that should have coordinated with polymer chains, which significantly improve ion transfer efficacy. Benefiting from the unique ion transport mode and enhanced interface stability, the designed PVDF-based electrolytes exhibit a high ionic conductivity (1.28 × 10^-4 S cm^-1), sufficient Li⁺ transference number (t_Li+ = 0.71) and excellent oxidation resistance (4.9 V vs. Li/Li⁺) at room temperature.