Inherently porous Co3O4@NiO core-shell hierarchical material for excellent electrochemical performance of supercapacitors

Supercapacitors have become a highly appealing candidate for next-generation energy storage system due to their high power density and long operation life. However, insufficient active materials utilization leads to a relatively low specific capacitance, which poses a significant challenge to their practical applications. In our work, hierarchical nanostructure with intrinsic porous NiO nanosheets uniformly dispersion on Co3O4 backbone is prepared through a facile and environmentally friendly method (denoted as Co3O4@NiO-X). The resulting well-defined porous core-shell material (Co3O4@NiO-1) displays a three-dimensional architecture, convenient ion transport channel and more exposed surface area, which demonstrates a significantly enhanced pseudocapacitance performance, with a high specific capacitance (692.8 F/g at a current density of 1 A/g) and excellent cycling performance (90.88% of initial value is retained after 2500 cycles). Furthermore, an asymmetric supercapacitor (ACS) is fabricated by employing Co3O4@NiO-1 core-shell material as positive electrode, activated carbon (AC) as negative electrode and 6 M KOH as electrolyte, which represents an excellent specific capacitance of 68.1 F/g (at 1 A/g) and provides high energy density of 35 Wh/kg at the power density of 540 W kg(-1), 23.4 Wh/kg at higher power density of 2722.1 W/kg, together with exceptional cyclic stability of 90.83% after 3000 cycles. The excellent electrochemical performance of Co3O4@NiO-1 materials demonstrates that rational design of porous core-shell structure can be a general strategy for multi-component materials to realize electrochemical energy storage devices with excellent performance.

Automated summary

Supercapacitors with hierarchical core-shell structure of Co3O4@NiO-1 demonstrate enhanced pseudocapacitance performance, high specific capacitance, and excellent cycling stability. By utilizing this material as positive electrode in an asymmetric supercapacitor, it achieves excellent specific capacitance and high energy density at different power densities, along with exceptional cyclic stability.