Fabrication of three-dimensionally heterostructured rGO/WO3•0.5H2O@Cu2S electrodes for high-energy solid-state pouch-type asymmetric supercapacitor

Advanced nanostructured electrodes containing more electroactive sites are essential to develop the high rate performance supercapacitors (SCs). Herein, we engineered two-dimensional (2D) reduced graphene oxide (rGO) on the diamond-like cubic tungsten oxide (WO3 center dot 0.5H(2)O), which was further decorated with the plant-like monoclinic copper sulfide (Cu2S) to form a three-dimensionally (3D) heterostructured rGO/WO3 center dot 0.5H(2)O@Cu2S electrode using a simple two-step hydrothermal method. This electrode exhibited a 1.5-fold higher areal capacitance of 545.6 mF cm(-2) (974.4 F g(-1)) over the WO3 center dot 0.5H(2)O based electrode in the redox active Na2SO4:K-4[Fe(CN)(6)] electrolyte. Meanwhile, the asymmetric pouch-type solid-state supercapacitor (APSC) was successfully operated at a high potential of 2 V with an excellent areal capacitance of 235.4 mF cm(-2) (269 F g(-1)) at 5 mV s(-1), an energy density of 32.6 mu Wh cm(-2) (37.3 Wh kg(-1)), cycling stability of 88% over 10,000 rapid charging/discharging cycles and a short relaxation time of 0.084 s at a frequency of 11.9 Hz. In addition, the density functional theory (DFT) simulations were used to explore the origin of the superb performance. It is found that the nanosheet-state graphene at the interface of WO3 center dot 0.5H(2)O and Cu2S could create the fast-electronic pathway, shorten the diffusion distance and give structural reliability. This novel strategy is expected to offer an effective way to develop new-generation supercapacitors with ultra-high energy storage ability.

Automated summary

A novel three-dimensionally heterostructured electrode was developed via a simple two-step hydrothermal method, which showed excellent performance in a redox active electrolyte and successfully operated at high potential in an asymmetric pouch-type solid-state supercapacitor. The electrode exhibited superb energy storage ability, cycling stability, and fast charge/discharge capabilities, paving the way for the development of new-generation supercapacitors.