Studies on potassium-ion conducting gel polymer electrolytes containing poly(vinylidene fluoride-hexafluoropropylene) polymer, potassium permanganate salt added with different plasticizers

In this work, a comparative study is presented utilizing a K+ conducting gel polymer electrolyte (GPE) system comprising of a poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) polymer matrix combined with potassium permanganate (KMnO4) salt and two different plasticizers as a binary combination of ethylene carbonate (EC) + propylene carbonate (PC) and tetraethylene glycol dimethyl ether (TEGDME). The electrolyte with TEGDME solvent shows an ionic conductivity (σ) of 7.01 × 10−6 S cm−1 with hopping of ions as charge transport behavior. The fabricated electrolyte possesses > 98% contribution from the ions, and the electro-chemical stability range is up to 3.2 V. The dielectric analysis shows that the electrolyte with TEGDME solvent possesses a higher value of the dielectric constant, dielectric loss, tangent loss, and dc conductivity, along with a higher free ion number density (N) in comparison to the counter-electrolyte specimens with EC:PC solvent. The thermal studies confirm the gel phase of both electrolytes with negligible weight loss till 100 °C. Polymer-salt complex interactions are confirmed using Fourier transform infrared spectroscopy (FTIR), while X-ray diffraction (XRD) analysis is used to study the variations in crystallinity brought about by the polymer and both electrolyte samples.