Exploring the electrochemical potential of redox-active mixed metal sulfide as an efficient electrode material for supercapacitor-battery hybrid

Hybrid supercapacitors have gained upsurge interest in the energy storage application, but still have room to improve their specific power and energy limits with the implication of electrode materials that have superior electrochemical performance. Herein, we study the synergistic effect of the synthesized cobalt sulfide (CoS) along with manganese sulfide (MnS). The electrochemical outcomes were analyzed in three-electrode cell configuration. The cobalt manganese sulfide (CoS/MnS) composite demonstrates considerable better performance having specific capacity of 590.3 C g−1 (3 mV s−1) and 501.3 C g−1 (1.0 A g−1). The CoS/MnS electrode was further employed as a positive electrode material in a hybrid supercapacitor (supercapattery) along with activated carbon (negative electrode). The device delivers an energy density of 46 Wh kg−1 and holds a power density of 1705 W kg−1. Further, the hybrid device also retains a remarkable specific capacity of 94.57% after 1,000 continuous charging–discharging cycles at 3 A g−1. The semi-empirical approach was employed to further investigate the hybrid nature of the device, which separates the diffusive and capacitive contributions in experimental cyclic voltammetry. These results demonstrate CoS/MnS composite may have a promising implication as an electrode material for high-performance energy storage applications.