Enhancing Solid-State Supercapacitors with Nitrogen Plasma-Activated PVA-KOH Gel Electrolyte

The development of high-performance solid-state energy storage devices is constrained by the limited ionic conductivity of gel electrolytes. To address this challenge, an inductively coupled nitrogen plasma (ICP) surface modification strategy was applied to poly(vinyl alcohol)-potassium hydroxide (PVA-KOH) gel electrolytes. The optimal plasma treatment parameters (150 W, 20 s) were identified based on ionic conductivity measurements. Comprehensive characterization confirmed that plasma treatment effectively introduced nitrogen-containing polar functional groups on the gel surface, induced surface nitrogen doping, increased surface roughness, and disrupted the hydrogen bond network. These synergistic microstructural modifications and chemical modifications increased interfacial polarity and facilitated ion transport, resulting in a 26% enhancement in the ionic conductivity compared with the pristine gel. Solid-state supercapacitors fabricated with the optimized gel electrolyte exhibits improved energy density, enhanced rate capability, and reduced interfacial impedance. These findings demonstrate that nitrogen-induced ICP treatment is an effective surface engineering strategy for improving gel electrolyte performance and advancing solid-state supercapacitor technologies.