Optimized synthetic route for reduced graphene oxide-decorated Cu0.33Co0.67Se2 nanorods on Ni foam integrated with N, S co-doped porous carbon to design high-performance hybrid supercapacitor electrodes

As advanced energy storage devices for commercial applications, hybrid supercapacitors (HSCs) assembled with electric double-layer capacitive- and battery-type electrodes combine the advantages of electric double-layer capacitors and batteries. Thus, it offers very high potential as well as higher energy density with sufficient durability than other energy storage devices. However, the selection of electrodes has a considerable determining effect on the performance of HSCs. Here, we developed an electrode material system for HSCs with copper-cobalt selenide composite on Ni foam with the assistance of carbon nanomaterial (reduced graphene oxide, rGO). The synergistic effects of Cu0.33Co0.67Se2 loaded with rGO led to excellent electrochemical performance with respect to a unique structure. Moreover, we synthesized N, S co-doped glucose-based porous carbon (NSPC) as an anode that exhibited stable electrochemical properties with interconnected networks. The configured HSCs (i.e., Cu0.33Co0.67Se2-rGO// NSPC) represented a wide voltage window (~1.6 V) and a superior energy density (~41.5 Wh kg−1) at a power density of ~801.5 W kg−1 that exhibited their inherent advantageous characteristics and combinatorial effects. Therefore, the efficient synergistic effects and superior electrochemical performances were optimized with appropriate ratios of the anode and cathode in the integrated system, which demonstrated high energy density and excellent structural stability.