CoS2/Bi2S3 nanoparticles embedded in self-supporting Pien Tze Huang graded porous carbon for enhancing supercapacitor performance

Abstract

The limited specific capacitance and cycling stability of current electrochromic supercapacitors significantly hinder their practical applications. To tackle these challenges, we developed a composite nanoparticle electrode material consisting of CoS₂/Bi₂S₃ and graded porous carbon derived from Pien Tze Huang biowaste (PTHPC) using a straightforward one-step hydrothermal method. Cobalt chloride hexahydrate (CoCl₂·6H₂O), bismuth nitrate pentahydrate (Bi(NO₃)₃·5H₂O), and sodium thiosulfate pentahydrate (Na₂S₂O₃·5H₂O) served as the sources of cobalt, bismuth, and sulfur, respectively. The unique architecture of the composites, characterized by rod-like Bi₂S₃ embedded within hollow CoS₂, creates a larger void space and enhances the electrolyte contact area. This design effectively reduces the electron and ion diffusion distances, which is crucial for improving the electrochemical performance. Notably, the synthesized 0.3Z-CoS₂/Bi₂S₃/PTHPC-20 composite electrode demonstrated exceptional performance, achieving a specific capacitance of 1289.2 F g⁻¹ and an energy density of 64.46 W h kg⁻¹ at a current density of 0.5 A g⁻¹. Furthermore, after rigorous testing involving 10 000 charge/discharge cycles, the electrode retained an impressive 86.7% of its initial capacitance, illustrating its excellent cycling stability and durability. This study highlights the potential of the Y-CoS₂/Bi₂S₃/PTHPC-X composites (where Y represents the total amount of different metals Co and Bi and X represents the mass of PTHPC) as high-performance electrodes for supercapacitors. Their unique structural characteristics and electrochemical properties position them as promising candidates for practical applications in energy storage systems.