High-performance cabbage-like FeNi3/CoP2@C electrode with 3D porous structure for supercapacitors

The development of supercapacitors relies heavily on the design and manufacture of innovative electrode materials. FeNi3 alloy-based electrodes show good chemical stability and corrosion resistance as positive electrodes. However, their high internal resistance and low electronic conductivity limit the large-scale application. In this work, the CoP2 particles with high electrical conductivity is integrated with FeNi3 nanoalloys to construct FeNi3/CoP2 heterostructure loaded on biomass-derived cabbage-like porous carbon. Combined with the experimental result and density functional theory, the introduction of CoP2 nanoparticles greatly improves the electrochemical properties of the prepared FeNi3/CoP2@C composite. By adjusting the annealing temperature, the FeNi3/CoP2@C-800 electrode displays a specific capacitance of 1135.5 C g−1 at 1 A g−1 with a surface area of 259.45 m2 g−1. In addition, the assembled FeNi3/CoP2@C-800//AC (activated carbon) asymmetric supercapacitor provides a high energy density of 52.2 Wh kg−1 at 525.0 W kg−1 and good electrochemical cycling stability with a capacitance retention rate of 84.23 % after 10,000 cycles. The study offers a feasible idea for making high-performance pseudocapacitive electrode material.