A novel all-in-one integrated flexible supercapacitor based on self-healing hydrogel electrolyte

Hydrogel electrolytes have special significance in the fabrication of flexible supercapacitors, which can withstand deformation and physical damage. Especially, there still exists a huge space in the design of self-healing integrated flexible supercapacitors with all-in-one structure that can reduce interfacial contact resistance, avoid the displacement and delamination deformations and prolong the lifetime. Herein, a self-healing integrated flexible supercapacitor has been prepared via in-situ polymerization of aniline on both sides of the physically cross-linked self-healing polyvinyl alcohol/phytic acid hydrogel electrolyte film. The self-healing integrated flexible supercapacitor has excellent tensile (three times the length without breaking), twisting and compression properties. Moreover, it exhibits a large areal capacitance of 356.5 mF cm−2 at 1.0 mA cm−2, high energy density of 31.7 μWh cm−2 at power density of 800 μW cm−2, and maintains 80% of the initial capacitance after five cutting/self-healing cycles, as well as outstanding cycling stability. Meanwhile, the integrated PVA/PA-PANI (0.8 M) supercapacitor possesses high areal specific capacitance of 356.5 mF cm−2 at 1.0 mA cm−2 and still reach 167.5 mF cm−2 at 5 mA cm−2. The specific capacitance remains about 160% of the initial capacitance after 5000 cycles. The remarkable electrochemical properties are attributed to the high ion diffusivity and low charge transfer resistance benefiting from the integrated all-hydrogel-state prototype. The novel self-healing integrated flexible supercapacitor with excellent capacitance performance and mechanical properties is expected to broad prospects for energy storage equipment in wearable electronics.