Constructing hierarchical CoGa2O4−S@NiCo2S4 core−shell heterostructures as a battery-type electrode material for hybrid supercapacitors.

Developing battery-type electrode materials with diverse core-shell heterostructures is the most crucial aspect in fabricating hybrid supercapacitors with high energy density and cycling stability. Additionally, mixed-metal sulfides are highly regarded due to their favorable theoretical specific capacity and conductivity. Here, we have devised hierarchical CoGa 2 O 4 −S@NiCo 2 S 4 core−shell heterostructures, featuring urchin−like and hexagonal morphologies. The needle−like shell significantly promotes the contact area with the electrolyte, facilitating OH− penetration to the core structure. This elevation improves both the diffusion−controlled process and reaction kinetics, thereby enhancing electrode material utilization and redox capability. Therefore, the optimized CoGa 2 O 4 −S@NiCo 2 S 4 exhibits a specific capacity of 959.0 C·g−1 (capacitance of 2131.1 F·g−1) at 1 A·g−1. The assembled CoGa 2 O 4 −S@NiCo 2 S 4 //AC hybrid supercapacitor delivers an energy density of 41.17 Wh kg−1 at 850 W kg−1, with a capacity retention rate of 93.60 % after 10,000 cycles. This study provides a novel approach to enhance the electrochemical performance of supercapacitors by optimizing reaction kinetics. • Urchin-like and hexagonal core−shell heterostructures were successfully synthesized. • The needle-like NiCo 2 S 4 facilitates the permeation of OH− into the CGOS core layer. • The diffusion−controlled processes of the composite electrode have been enhanced. [ABSTRACT FROM AUTHOR]