A Single Robust Hydrogel Film Based Integrated Flexible Supercapacitor

Integrated configuration can greatly improve the stability of an energy-storage device in a large or repeated mechanical deformation process, but there is little attention paid to develop this conceptual energy-storage device. Here, we successfully design two embedded polypyrrole (PPy) layers as electrodes and a boron cross-linked PVA(poly(vinyl alcohol))/KCI hydrogel film as electrolyte to construct an integrated electrode electrolyte electrode flexible super capacitor (so-called all-in-one supercapacitor). The boron cross-linked PVA/KCI hydrogel film (B-PVA/KCI) is prepared by simple physical and chemical cross-linking methods. Then, the conducting PPy is embedded in the B-PVA/KCI film by in situ growth to form a PPy/B-PVA/KCI composite film, which shows superior toughness and strength when it undergo large deformations, such as stretch, twist and compression. The integrated flexible supercapacitor can obtain a large areal capacitance of 224 mF cm(-2) and a remarkable energy density of 20 mu Wh cm(-2). Furthermore, such device exhibits excellent electrochemical stability under various bending angles (0 degrees, 90 degrees, and 180 degrees) or 500 bending-releasing cycles, which due to the integrated electrode-electrolyte-electrode configuration can avoid the fall-off of electrode materials from the substrates and overcome the relative displacement between electrode and electrolyte layers during the consecutive bending cycles.