Nickel cobalt sulfide composite nanosheet anchored on rGO as effective electrode for quasi-solid supercapacitor

A solid supercapacitor based on inorganic/organic composite electrolyte has great promise as a fresh wave of energy storage structure in building engineering owning to its inherent mechanical robustness. Unfortunately, the limited capacity and energy density of these supercapacitors are still challenging. Here, rGO/NixCoyS elec-trodes were fabricated by in-situ growth on nickel foam (NF). The edge sulfur-enriched NixCoyS nanosheets were equally anchored on rGO surface, increasing the number of electrochemical active sites, accelerating ion diffu-sion and improving the electrical conductivity. The morphology and electrochemical behavior of the rGO/Nix-CoyS composite are remarkably affected by the Ni to Co molar ratio. It turned out that the rGO/NixCoyS composite with a Ni to Co molar ratio of 1:1 (rGO/Ni1Co1S) exhibited a high capacitance of 4.55 F cm-2 at 1 mA cm-2. Subsequently, a novel quasi-solid supercapacitor was assembled using rGO/Ni1Co1S cathode, rGO/Fe2O3 anode as well as inorganic/organic composite solid electrolyte. The device achieved a high energy density of 3.6 & mu;Wh cm-2 at a power density of 163.2 & mu;W cm-2, and moderate self-discharge (SDC) process, outperforming those of earlier reported structural devices. The practical application demonstration proves the feasibility of ternary rGO/Ni1Co1S electrode combined with inorganic/organic composite solid electrolyte in building energy storage field.