Superior cycling stability of a crystalline/amorphous Co3S4 core–shell heterostructure for aqueous hybrid supercapacitors

Abstract

In this article, a novel crystalline/amorphous Co₃S₄ core–shell heterostructure supported on nickel foam is fabricated through a facile method. Due to the unique structure of the crystalline Co₃S₄ core that provides stable mechanical support and surface-active sites and the amorphous shell that facilitates diffusion and reaction of electrolyte ions, the obtained crystalline/amorphous Co₃S₄ electrode shows a superior pseudocapacitive performance of 2.65 F cm⁻² (2038.5 F g⁻¹) at a current density of 5 mA cm⁻² and even 1.81 F cm⁻² (1392.3 F g⁻¹) at 50 mA cm⁻². In addition, the Co₃S₄//AC exhibits a relatively high energy density of 54.78 W h kg⁻¹ at a power density of 400.02 W kg⁻¹ and excellent cycling performance (about 94.8% capacitance retention over 32 500 cycles). The kinetic analysis reveals a diffusion controlled faradaic characteristic of Co₃S₄ (73.21% diffusion-controlled contribution). Moreover, the fabrication process presented in this work is facile, cost-effective, and environmentally benign, offering a feasible solution for fabricating next-generation high-performance energy storage devices.