The integration of Ni-Co oxide/phosphide/sulphide composites into nanowire arrays on Ni foam as supercapacitor electrode for boosting energy storage performance

In this work, Ni-Co oxide/phosphide/sulphide (NCOPS) multicomponent composites are designed and constructed as an electrode material with high specific capacitance for supercapacitors. The Ni-Co precursor was firstly synthesized by hydrothermal method, and then treated by in-situ phosphating-sulfurizing simultaneously to obtain high performance NCOPS electrode material. The characterization results confirm that the NCOPS nanowire arrays are composed of phosphides (Ni2P and Co2P), sulfides (Ni3S2 and Co3S4), and oxide (NiCo2O4), thus obtaining good interfacial effect between different components, giving NCOPS electrode outstanding charge storage performance for supercapacitors. In addition, the interwoven nanowire arrays have abundant gaps. Moreover, permeable microstructure with bubble pores appears in the inner region of the nanowires. The combination of these unique nanowire micro-structures and multiple components helps to shorten the diffusion distance of ions, facilitate the transfer of ions and charges in the electrolyte, and alleviate the volume expansion of the material. As expected, the specific capacitance of the NCOPS electrode reaches 2915.6 F g-1, with 80.39 % of the specific capacitance retained after 4000 charge/discharge cycles at a constant current of 5 A g-1. This study presents another approach for developing high-performance energy storage electrode materials.