A 3D nanocomposite of NiCo2S4/CuCo2S4 heterostructure synthesized by chemical precipitation for asymmetric supercapacitors

In recent years, transition metal sulfides have been regarded as a promising energy storage material for supercapacitors, due to their high theoretical specific capacity and conductivity compared with other si-milar metal oxides and hydroxides. However, the sluggish diffusion dynamics and low capacitance impede its practical implement application. Herein, an advanced 3D nanocomposite of NiCo2S4/CuCo2S4 hetero-structure was designed via a time-saving, safe and efficient approach. The mass transfer kinetics of NiCo2S4/CuCo2S4 nanocomposite has been significantly promoted owing to this novel heterostructure. Therefore, the NiCo2S4/CuCo2S4 electrode materials reveal a superior specific capacitance (180.8 mAh g(-1) at 2 A g(-1)) and excellent rate properties (84.7% capacitance retention from 2 to 20 A g(-1)). The asymmetric supercapacitor device assembled with NiCo2S4/CuCo2S4 and activated carbon has an energy density of 37.0 Wh kg(-1) at 400 W kg(-)1 and outstanding cyclic stability (93.3% remained after 10,000 cycles at 10 A g(-1)). Density functional theory (DFT) calculation further proves the electronic structure and the charge transfer can be tuned by the heterostructure of NiCo2S4 and CuCo2S4. This work offers a new perspective to design a high-performance electrode material in the field of supercapacitors. (c) 2023 Published by Elsevier B.V.

Automated summary

In recent years, transition metal sulfides have been considered as a promising energy storage material for supercapacitors due to their high specific capacity and conductivity. However, the slow diffusion dynamics and low capacitance limit their practical applications. In this study, a 3D nanocomposite of NiCo2S4/CuCo2S4 hetero-structure was designed, which significantly improved the mass transfer kinetics. The NiCo2S4/CuCo2S4 electrode materials exhibited superior specific capacitance and rate properties, and the asymmetric supercapacitor device showed high energy density and cyclic stability.