A new cadmium oxide (CdO) and copper selenide (CuSe) nanocomposite: An energy-efficient electrode for wide-voltage hybrid supercapacitors

In this paper, cadmium oxide (CdO) was effectively developed on copper selenide (CuSe) nanoparticles via the wet-chemical method for the first time to explore their electrochemical properties for hybrid supercapacitors (HSC). The XRD Raman analysis proves the successful formation of the CdO, CuSe, and CdO-CuSe nanocomposite. The morphological results exposed that CdO and CuSe are composed of irregular particles-like morphology. Cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) analysis demonstrated the battery-type behavior of the electrode materials, with prominent redox peaks and voltage plateau in the GCD profile with good reversibility. Interestingly, it was observed that the freshly prepared CdO-CuSe electrode displays a relatively higher capacity (386 C/g) compared to CdO and CuSe electrodes (175 and 216 C/g). Furthermore, we built a CdO-CuSe//AC HSC, which expanded the voltage limit to 1.8 V. It delivered a high energy and power densities of 51 Wh kg⁻¹ and retained 16 Wh kg⁻¹ when power density reached its maximum value of 6488 W kg⁻¹. More importantly, a stable cycling performance (94.8%) was attained after 9000 cycles at the highest current rate of 15 A g⁻¹, which can be attributed to the high conductivity, which offers more active sites for electrolyte ions on the electrode surface.