Enhancing asymmetric supercapacitor performance with NiCo2O4–NiO hybrid electrode fabrication

Abstract

Spinel metal oxide with an extra crystalline phase is an active way to enhance the performance of the supercapacitor. Herein, a facile hydrothermal approach has been established for synthesizing nanocrystalline NiCo2O4 with an extra NiO phase material as the potential electrode for a supercapacitor. XRD analysis is executed to expose the crystalline environment and found to be dual phases ie. NiO and NiCo2O4. Further, the chemical environment of these phases is identified in FTIR, EDS, X-ray photoelectron spectroscopy, elemental mapping, and Raman analysis. The morphological analysis (SEM) of the material showed that the formation of tiny particulates aggregates become uniform in size, which consists of a nearly spherical structure. NiCo2O4–NiO showed a remarkable electrochemical performance in a 2 M potassium hydroxide. The maximum capacitance was achieved as 866 F/g at a sweep rate of 5 m V/s, which is quite higher than the normal pristine NiCo2O4. The material delivered a capacity retention of 85% over 5000 cycles. This high performance was attributed to the NiO phase in NiCo2O4 material inducing an additional charge at the boundary, prominent to synergistic effect and rapid electron and ion passage. Hence, overall, the superior performance with extra NiO phase could be beneficial for developing spinel metal oxide electrodes for battery-type supercapacitor applications.