Exploring the synergistic integration of graphene nanoplatelets as electrodes with gel polymer electrolytes for high-performance supercapacitor applications: a study of Li-salt dynamics

Gel polymer electrolytes, constituted by plastic crystals, are an emerging class of semi-solid with desirable mechanical, thermal and electrochemical characteristics rendering them suitable for energy storage and conversion devices. This work presents the exploration of graphene nanoplatelets as electrodes with a novel gel polymer electrolyte based on poly (vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), incorporating non-ionic plastic crystal (succinonitrile), organic ionic plastic crystal (1-ethyl-1-methyl piperidinium bis(trifluoromethanesulfonic)imide), and lithium bis (trifluoromethanesulfonyl) imide (Li-TFSI). With the addition of Li-TFSI in the bare electrolyte mentioned, the physical and electrochemical parameters are significantly enhanced. The ion diffusion coefficient improved by ∼122 %, with a specific capacitance, energy, and power densities of ∼67 F g⁻¹, ∼ 9 Wh kg⁻¹ and ∼119.2 kW kg⁻¹, respectively. The EDLC illustrates overall stable and high-rate performance upto ∼42 Ag⁻¹ with the coulombic efficiency of 96–98 % and depicting only ∼8.8 % initial fading. The device has capability to glove a LED upto ∼13 min indicating substantial practical efficiency of energy storage of supercapacitor.