Flexible supercapacitor electrodes based on modified binary metal phosphites on three dimensional graphene sponge

In this paper, two flexible graphene-based materials were prepared by electrochemically depositing FeCoP and FeZnP on graphene sponges (GS) as self-standing electrodes for high-performance electrochemical capacitors. The structural and morphological properties of FeCoP/GS and FeZnP/GS electrodes were characterized using different spectroscopic techniques. As a result, the FeCoP/GS and FeZnP/GS electrodes demonstrated a high specific capacitance of 2100 and 1100 F/g at 1.0 A/g, great cycling stability after 10,000 cycles maintaining 80 % and 74 % of its initial capacitance, respectively, which showed better performance than GS electrode. Moreover, two asymmetric supercapacitors were fabricated with FeCoP/GS and FeZnP/GS electrodes and GS; FeCoP/GS//GS and FeZnP/GS//GS circuits displayed a specific capacitance of 1100 and 780 F/g at 1.0 A/g and an outstanding energy density of 185 and 98 Wh/kg at a high power density of 5.6 and 3.8 kW/kg, respectively. Therefore, the as-fabricated electrodes hold great potential in the field of energy storage. •Fabrication of a novel flexible graphene-based sponge material (3D FeCoP/GS and FeZnP/GS).•Characterization of FeCoP/GS and FeZnP/GS with various techniques.•The flexible FeCoP/GS//GS and FeZnP/GS//GS ASC devices.•The FeCoP/GS and FeZnP/GS is a promising candidate for producing high-energy-density electrode materials in supercapacitors.