Mechanically Stable All Flexible Supercapacitors with Fracture and Fatigue Resistance under Harsh Temperatures

Abstract For practical applications in the fields of aerospace and robotic engineering, flexible energy storage devices must be stable under environmental temperatures and different deformed situations. In this work, a mechanically stable supercapacitor (SC) at harsh ambient temperatures is synthesized by in situ polymerization of polyaniline(PANI) onto a double network hydrogel electrolyte from cross‐linked polyvinyl alcohol(PVA) and polyacrylamide/acrylic acid (PAM/AA) networks. The highly integrated structure endows the supercapacitor with unprecedented mechanical performance. The devices can endure 608% tensile strain and be stretched up to 50% without noticeable hysteresis, demonstrating fatigue and fracture resistance under thousands of cyclic loads. Benefiting from an all‐flexible configuration through seamless integration of the PANI electrode, the supercapacitor presents a high specific capacitance of 95.8 mF cm –2 . It can also work as an all‐flexible device and maintain its stable output under complex deformations, even physical damages. Furthermore, the device delivers excellent environmental adaptability by steady electrochemical performance after operating at extreme temperatures from −60 to 100 °C. Such a versatile supercapacitor presents a potential application in integrated flexible electronic systems by powering functional devices in harsh environments.