Efficient ion transport mode and stable Li+-interface induced by the introduction of HA-SiO2 in PVDF-based electrolytes for solid-state lithium metal batteries

J Colloid Interface Sci. 2024 Dec 16;683(Pt 1):641-651. doi: 10.1016/j.jcis.2024.12.109. Online ahead of print.

Abstract

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 (tLi+ = 0.71) and excellent oxidation resistance (4.9 V vs. Li/Li+) at room temperature.

Keywords: Li(+) transport kinetics; Li(+)-hopping sites; PVDF-based electrolytes; Residual solvents.