Electrochemical investigations on PVDF-HFP-based sodium ion conducting gel polymer electrolyte added with copper particles

Dispersion of inorganic fillers helps in increasing the disorderness in the polymer electrolytes and inculcating ion dissociation. In the present work, the impact of copper (Cu) micro-particles on the structural, thermal, and electrochemical behavior of a sodium-ion conducting gel polymer electrolytes comprising Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer and a liquid electrolyte of NaBF₄ salt in a mixture of ethylene carbonate and propylene carbonate is presented. The free-standing and flexible films of the gel polymer electrolyte with uniform dispersion of the Cu micro-particles were prepared by solution casting techniques. The optimized electrolyte composition displays jump in the conductivity with an excellent ionic conductivity of 5.19 mS cm⁻¹ at room temperature. The optimized electrolyte composition shows improved electrochemical stability of ~ 4.2 V. The Cu particles strike on two major fronts in the electrolyte system as; it helps ion dissociation as evident from dielectric studies and increase amorphicity of polymer backbone as evident from X-ray diffraction (XRD) and differential scanning calorimetry (DSC) studies.