NiS nanoparticles assembled on biological cell walls-derived porous hollow carbon spheres as a novel battery-type electrode for hybrid supercapacitor

Designing a battery-type electrode material with high electrochemical performance based on eco-friendly and sustainable strategy has great significance for the development of supercapacitors. Herein, NiS nanoparticles are deposited on the surface of the porous hollow carbon spheres (PHCSs) derived from inexpensive and pollution-free yeast cells wall by an in situ hydrothermal process, forming a litchi shell-like three-dimensional (3D) double-shell structure. The PHCSs as a carbon substrate can effectively suppress the aggregation of NiS nanoparticles and ensure more ground storage sites to enhance the performance of the electrode material. More notably, the reaction concentration of nickel ion has a remarkable effect on the electrochemical performance of composites. The optimized sample shows a high specific capacity of 531.5 C g⁻¹ at 1 A g⁻¹, excellent rate capability of 412.1 C g⁻¹ at 10 A g⁻¹ and outstanding cycling life span of 83.3% after 5000 cycles. Furthermore, the assembled hybrid device delivers a high energy density of 24.4 Wh kg⁻¹ at a power density of 767 W kg⁻¹ and an excellent cycle stability by delivering 89.3% capacitance retention after 5000 ultralong cycles. This work offers a feasible strategy to synthesize economical and efficient electrode materials and demonstrates its enormous potential in energy storage.

A novel NiS/porous hollow carbon sphere composite with double-shell structure was synthesized by a green and available self-template method, which exhibits superior supercapacitor performance.