Air-Stable, All-Solid-State Supercapacitors Designed for Covalent Bonds of Acrylic Polymeric Binders and Ionogel Electrolytes

Conventional polymeric binders in supercapacitors exhibit poor ionic conductivity and weak interfacial adhesion, limiting their electrochemical performance and mechanical durability. To address these challenges, we develop an air-stable, all-solid-state supercapacitor utilizing a functional polymeric binder with covalent bonding and strong adhesion properties. The poly(ethyl acrylate-co-allyl methacrylate) binder enhances interfacial stability, while the ionogel electrolyte, composed of lithium perchlorate in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide within a poly(ethylene glycol diacrylate) matrix, provides high ionic conductivity, mechanical flexibility, and high air stability. The presence of covalent bonding between the binder and electrolyte significantly improves ion transport, leading to a 79.3% increase in specific capacitance (55.8 F g–1 at 0.2 A g–1) compared to systems without covalent bonding. Electrochemical impedance spectroscopy confirms a lower charge transfer resistance, while galvanostatic intermittent titration technique analysis further verifies that covalent bonding enhances ion diffusion. The supercapacitor retains 96% capacitance after 90 days in ambient air and remains fully functional after 500 bending cycles, demonstrating mechanical durability. Successful LED and Christmas tree illumination further confirms its real-world applicability. This strategy establishes a promising approach for developing high-performance flexible energy storage devices.