An amphiphilic PVDF-g-POEM double comb copolymer-based solid-state electrolyte for EDLC applications: electrochemical and electrical property studies

A modified polyvinylidene fluoride (PVDF)-based electrolyte, amphiphilic polyvinylidene fluoride-graft-poly(ethylene glycol)methyl ether methacrylate (PVDF-g-POEM), double comb copolymer is synthesized for use as a solid-state electrolyte within an electric double layer capacitor (EDLC). The double comb copolymer is synthesized via atom transfer radical polymerization (ATRP). The solid-state electrolyte prepared using the amphiphilic PVDF-g-POEM double comb copolymer shows increased ionic conductivities, compared to that of the hydrophobic PVDF-based electrolyte. Incorporating hydrophilic POEM chains into semi-crystalline hydrophobic PVDF results in nanophase separation and decreased polymer crystallinity, yielding facile ion transport pathways and enhancing the ionic conductivity. The electrochemical and electrical characteristics of the prepared EDLC cells are investigated using cyclic voltammetry, galvanostatic charge-discharge cycling, and impedance spectroscopy. The specific capacitance of 38.07 F g⁻¹ (0.5 A g⁻¹) was achieved with an energy density of 25.59 W h kg⁻¹ at a power density of 0.275 kW kg⁻¹. After 8000 cycles (1 A g⁻¹), the cells show a capacitive retention of 95.6%, with an 85% coulombic efficiency.