Improved Performance of Organic-Inorganic Hybrid Gel Polymer Electrolyte by In Situ Incorporation Based on Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) for Lithium-Ion Batteries.

Abstract

Novel organic-inorganic hybrid gel polymer electrolyte (GPE) membranes, with poly-(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) serving as a polymer matrix host, were fabricated via the simple and efficient electrospinning technique for lithium-ion batteries. Additionally, inorganic nanoparticles SiO₂ were incorporated into the polymer through a one-step in situ process facilitated by a silane coupling agent. The chemical structure, surface morphology, liquid electrolyte uptake, thermal stability, and electrochemical properties of the organic-inorganic hybrid membranes were characterized. The results illustrated that the gel electrolyte membrane demonstrated good nanoparticle dispersion, excellent thermal stability, a larger amorphous region, a high electrolyte uptake of 410%, and a high electrochemical window of up to 4.9 V. Significantly, the ionic conductivity and lithium-ion transference number reached as high as 6.23 mS/cm and 0.57 at room temperature, respectively. These outstanding thermal and electrochemical performances can be attributed to the synergistic effect of the good dispersion of inorganic nanoparticles within the polymer matrix and the unique cross-linked porous structure. Moreover, the cells assembled with graphite as the anode, lithium metal as the counter electrode, and the prepared membrane serving as both the electrolyte and separator delivered remarkable cycling and C-rate performance. Specifically, the charge capacity remained at 311 mAh/g after 200 cycles at a C-rate of 0.1C, achieving an 87% capacity retention relative to the first cycle. When the cell underwent charge-discharge cycles from 0.1C to 1C and then back to 0.1C, the charge capacity could recover 96% of that in the first cycle.