Zn-doped NiS2 wrapped by RGO nanosheets revealing improved electrochemical performances for supercapacitor application

Abstract

Designing low-cost, high-performance electrodes are critical for assembling efficient energy storage devices. Herein, we have designed Zn-doped NiS₂ heterostructures wrapped by reduced graphene oxide (RGO) nanosheets via a facile hydrothermal route, and investigated their (ZNSRs) electrochemical energy storage properties. Hierarchical porous interconnected RGO nanosheets with high specific surface area and excellent conductivity not only provide good charge/ion fast transfer channels, thereby improving the reaction kinetics, but also promote the dispersion of zinc-nickel sulfide nanoparticles, thus improving the utilization of zinc-nickel sulfide with high specific capacity property. Meanwhile, the Zn-doped to form zinc-nickel sulfide heterostructure can improve the electrochemical reactivity of the nickel sulfide electrode, which can be beneficial to synergistically improve the energy storage properties. The test results show that the fabricated ZNSRs electrodes exhibit excellent energy storage performances. The optimal ZNSR-0.3 electrode not only exhibits a high specific capacity of 221.7 mAh g⁻¹ at 0.8 A g⁻¹, but also the hybrid supercapacitor assembled with the designed RAC negative electrode also delivers a high energy density of 45.1 Wh kg⁻¹ (at power density of 603.9 W kg⁻¹) and excellent long-term cycling stability (80.67 % capacity retention after 22,000 cycles). The fabricated ZNSR-0.3 electrode is demonstrated to be a promising alternative electrode in efficiency hybrid supercapacitor application.