Exploring the charge storage mechanism in high-performance Co@MnO₂-based hybrid supercapacitors using Randles-Sevcik and Dunn's models

Hybrid supercapacitors are energy storage technology offering higher power and energy density as compared to capacitors and batteries. Cobalt-doped manganese oxide (Co@MnO2) was synthesized using an easy and affordable sol-gel process and measured the electrochemical properties. A value of the specific capacity of 1141.42 Cg(-1) was obtained which was larger in comparison to the reference sample (MnO2 = 673.79 Cg(-1)). The value of the specific capacitance was achieved 1902 Fg(-1). To design a hybrid supercapacitor device, Co@MnO2 was used as the positive electrode and the activated carbon was employed as the negative electrode in two-electrode assembly. According to calculations, the measured value of the specific capacitance of Co@MnO2 was 713.25 Fg(-1). The charge storage mechanism is supported with the help of Randles-Sevcik and Dunn's models. The estimated value of energy and power densities were 3200 Wh kg(-1) and 24 Wkg(-1), respectively. The stability of this device was checked by putting it to 1000 charging and discharging cycles, and it retained 86% of its initial capacity. Our result provides a platform for enhancing the functionality of energy storage systems.