Structural rearrangement by Ni, Cr doping in zinc cobaltite and its influence on supercapacitance

Transitional metal oxides are prevalent in the energy storage devices due to their remarkable electrochemical activity and charge storage capability. In this study, a spinel structured zinc cobaltite (ZnCo2O4) is doped with Ni and Cr to form a novel (Ni,Cr:ZnCo2O4) electrode material towards supercapacitor (SC) applications. Dopants served as a conductivity booster, particle size reducer and active sites provider benefitting the electrochemical activity. Comparatively, the doped sample delivered a higher capacitance value of 575 Fg-1 in the potential range of 0-0.6V with 1 M KOH solution as an electrolyte which is higher than that of the pristine material and better cyclic stability is improved from 82.2% to 90.24% for 2000 cycles. The specific capacitance value of 30 Fg-1 and 73 Fg-1 at 0.75 Ag-1 is achieved for the fabricated asymmetric supercapacitor device with Ni,Cr:ZnCo2O4 using Cu foil and Ni foam as current collector respectively. The device assembled with doped sample using Ni foam current collector has an energy density of 16.3 WhKg-1 and a power density of 0.9 KWKg-1 superseding the performance of the devices constructed with the pristine ZnCo2O4. The performance of Ni and Cr doped spinel structured zinc cobaltite device indicates a notable progress towards the direction of better performance supercapacitor applications.

Automated summary

The doped spinel structured zinc cobaltite electrode material exhibited higher capacitance value and improved cyclic stability in supercapacitor applications. Assembled asymmetric supercapacitor device with doped sample using Ni foam as current collector showed higher energy density and power density, surpassing the devices constructed with the pristine material.