Interfacial integration of ultra-thin flexible electrochemical capacitors via vacuum filtration based on gelatinized fibrous membranes

Hydrogel electrolytes have been widely used for constructing flexible electrochemical capacitors. However, the weak interface bonding between hydrogel electrolytes and electrode materials often leads to a deterioration of the electrochemical performance during deformation. Herein, a universal fabrication method utilizing vacuum filtration was developed to ensure a robust electrode–electrolyte interface. By in situ gelation of fibrous membranes, we overcome the hurdle of hydrogel filtration, enabling the construction of ultra-thin all-in-one electrochemical capacitors. This strategy has been demonstrated as a universal platform for constructing paper-like devices with an all-in-one structure that is applicable to a variety of electrochemical energy storage systems, including symmetric supercapacitors, asymmetric supercapacitors, ammonium-ion hybrid capacitors, and zinc-ion hybrid capacitors. Among these, the zinc-ion hybrid capacitors demonstrate a high specific capacitance of 474.1 F g−1 and a high energy density of 41.8 mW h cm−3. Additionally, series-connected electrochemical capacitors can power devices under deformations of bending, folding, and curling, showcasing the potential application of wearable energy storage.