The influence of pulse magnetic field intensity on the morphology and electrochemical properties of NiCoS alloys

Abstract In this study, we synthesized arrayed NiCoS alloys as electrode material of supercapacitors via a customized hydrothermal reaction device assisted by pulse magnetic field and studied the effect of pulse magnetic field intensity on the morphology and electrochemical performances of NiCoS alloys. The results showed that the diameter of the rod-shaped NiCoS alloys reaches its minimum value of 10 nm and the arrangement of the arrayed grains is most regular at a peak current density of 9Adm−2 flowing through the electromagnetic induction coil. Consequently, the specific capacity of that sample reaches a maximum value of 161.2 mAhg−1 at 2Ag−1, which drops to 118.7 mAhg−1when the current density increases from 2Ag−1 to 10 Ag−1. The optimized sample also exhibits an excellent long-term cycling performance with a retention ratio of 84.6% over 5000 cycles in 2 M KOH electrolyte. The remarkable electrochemical performances may be attributed to the effect of pulse magnetic field on the nucleation and growth of NiCoS alloys, which could enlarge its surface area and improve its crystal dendrite quality.