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 electrodes 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 diffusion and improving the electrical conductivity. The morphology and electrochemical behavior of the rGO/NixCoyS 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 μWh cm−2 at a power density of 163.2 μW 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.