Synthesis of holey graphene networks functionalized with p-phenylene diamine monomers for superior performance flexible solid-state supercapacitors

p-Phenylene diamine (PPD) was selected as functional monomer to modify the holey graphene networks (rHGO-PPD) by a facile one-step hydrothermal method . rHGO-PPD was employed as promising active electrode materials to apply in supercapacitors (SCs), which exhibited excellent electrochemical performance, including high specific capacitance (375.5 F/g at current density of 0.5 A/g), excellent rate capability and good cycling stability due to the contribute of pseudocapacitive behavior of PPD. For further pursuit of great value in the practical application, the rHGO-PPD was used to fabricate symmetric SCs and flexible solid-state SCs (FSSCs). The FSSCs possessed high specific capacitance of 332.4 F/g, maintained good cycling stability of 74% of its initial capacitance up to 5000 charge-discharge cycles. In addition, FSSCs also exhibited extraordinary mechanical flexibility, and also maintained excellent stability even in a harsh environment. Remarkably, the FSSCs showed excellent long-term storage stability, and the capacitance kept about 88% after ten weeks of storage. Therefore, the FSSCs based on rHGO-PPD electrode material display promising application in flexible energy-storage devices.