Synthesis of porous graphitic carbon electrode materials based on Fe-Ni dual transition metal elements for high-performance supercapacitors

The development of carbon materials with both porous structures and high graphitization degrees is an essential approach to preparing carbon-based electrodes using widely available and green renewable biomass. Based on this, in this study, a novel method coupling iron-nickel hydrothermal synergistic catalytic graphitization with KOH activation was designed, which achieved the catalytic construction of the graphitic structure during the activation and pore expansion process. The resultant material (PS@FeNi-8) exhibits a hierarchical porous structure containing a large number of microporous and mesoporous structures with a high specific surface area of 2044.67 m2 g- 1. PS@FeNi-8 also exhibits distinct graphite regions composed of multilayered carbon nano- sheets stacked with a uniform bar-like structure ranging from 2 to 5 nm in thickness. Electrochemical performance testing of PS@FeNi-8 in supercapacitors reveals a maximum mass specific capacitance of 391.34 F g- 1 under a three-electrode configuration at a current density of 1 A g- 1, with a capacitance retention of 81.95 % observed when the current density is increased to 10 A g- 1. In a two-electrode configuration, the material achieves a power density of 8.4 W h kg-1 at a power density of 625 W kg-1, while maintaining an energy density of 7.7 W h kg-1 at a power density of 3125 W kg-1. Furthermore, after 50,000 charge/discharge cycles, PS@FeNi-8 demonstrates a remarkable capacitance retention of 94.05 %.