▎ 摘　　要

The fabrication of flexible supercapacitors comprising highly conducting energy storage electrode material catering high capacity, energy density and longer stability without cell deformation is a challenging task. Herein, we develop unique g-C3N4.7/N-doped graphene nanocomposite electrode material which shows robust charge storage characteristics via reducing the interfacial resistivity. A flexible all-solid-state symmetric device is assembled by employing g-C3N4.7/N-doped graphene composite and redox active ([EMIM][BF4]/PVDF/KOH/pphenylenediamine) electrolyte cum separator. It delivers a high areal capacitance of 141 mF cm-2, power density of 0.70 mW cm-2 and an energy density of 0.047 mWh cm-2 at 1.11 mA cm-2 current density with 98.9% capacity retention at 2.2 V potential till 18,000 cycles and nearly 95% Coulombic efficiency till 20,000 cycles. Bending angle-based performance studies indicate the stability of capacity at any bending angles (0, 35, 60, 90, 150, 180 degrees). The key to the significant functioning of the cell is ascribed to the advantageous synergism involved in g-C3N4.7/N-doped graphene nanocomposite, high surface area and mesoporous structure endowing high electrode-electrolyte interface interaction sites along with enhancement in the electronic conductivity as evidenced.