Mechanically stable all-hydrogel supercapacitor achieved by electrodes with excellent flexibility and high capacitance performance

An all-in-one flexible and all-solid-state matrix conductive hydrogel electrode with high capacitance has been effectively generated in this work. Using multi-dimensional materials collaborative construction, one-dimensional (1D) polypyrrole (PPy) nanofibers and two-dimensional (2D) reduced graphene oxide (RGO) nanolayers are incorporated into a three-dimensional (3D) polyvinyl alcohol (PVA) matrix. The cross network of PVA effectively prevents PPy aggregation and inhibits the collapse of the PPy skeleton, while is uniformly distributed and immobilized the RGO layer within the three-dimensional matrix of physically cross-linked PVA. This further enhances the overall material's mechanical properties and the conductivity. The confined growth PPy provides certain capacitive properties to the material. The hydrogen bonding and synergistic effect between each component make the PVA/RGO/PPy-0.5 hydrogel electrode to have an excellent area specific capacitance of 483.3 mF/cm2 at 1 mA/cm2, along with outstanding flexibility and 91.2 % high cycle stability after 5000 charge-discharge cycles. By employing a layer-gelation strategy, an all-in-one flexible and all-solid-state supercapacitor set has a high energy density of 44.6 μWh/cm2 and high cycling stability of 94.8 % after 10,000 charge-discharge cycles. Moreover, there is no significant capacitance loss when supercapacitor bent at various angles, demonstrating the great potential of the feasible flexible supercapacitors with high capacitance and deformability made possible through multi-dimensional materials collaborative construction.