Self-assembled CoS2/NiCo2S4/RGO nanohybrids as advanced electrode for hybrid supercapacitor with enhanced energy density and ultra-long durability

Abstract

Hybrid supercapacitors (HSCs), with enhanced energy density while maintaining high output power and ultra-long service life, have attracted much attention and research in efficient and sustainable new energy storage devices. Herein, we have successfully designed and synthesized novel CoS2/NiCo2S4/RGO nanohybrids with reduced graphene oxide co-modified by various transition metal sulfide (TMS) components using a facile one-step hydrothermal method. Benefiting from the excellent electrochemical activity, high stability and high capacity of the TMSs, as well as the more exposed electroactive sites and more favorable channels for ion transport brought by the good dispersion of TMSs nanoparticles prompted by the porous nanostructured surface constructed by RGO nanosheets, the synthesized CoS2/NiCo2S4/RGO nanohybrid exhibits excellent electrochemical energy storage performance with a high specific capacity of 133.6 mAh g−1 and outstanding rate capability. Additionally, the CoS2/NiCo2S4/RGO//N-RGO aqueous HSC assembled by CoS2/NiCo2S4/RGO electrode and as-prepared N-RGO electrode delivers a maximum energy density of 21.6 Wh kg−1, a power density of 7082.9 W kg−1, and an excellent ultra-long durability with 86.16 % capacity retention after 20,000 cycles. The novel CoS2/NiCo2S4/RGO nanohybrid with simple synthesis process and excellent energy storage performance is a promising alternative advanced electrode material in high-safety, sustainable and high-performance aqueous energy storage devices.