Controlled growth and interaction of NiCo₂S₄ on conductive substrate for enhanced electrochemical performance

The controlled nanostructure growth and its strong coupling with the current collector are key factors to achieve good electrochemical performance of faradaic-dominant electroactive materials. In this work, we demonstrate binder-less and additive-free hydrothermal and physical vapor doping methods for the synthesis of nickel cobalt sulfide (NiCo₂S₄) deposited on different conductive substrates such as pristine nickel foam (NF), reduced graphene oxide coated on NF (rGO/NF), and N-doped rGO coated on NF (N-rGO/NF). The size and density of NiCo₂S₄ nanosheets are controlled through the strong coupling with N-rGO/NF and rGO/NF. This controllable synthesis allows N-rGO/NF to achieve better electrochemical performance such as high capacity of 623.5 mAh g⁻¹ at 4 mA cm⁻², energy efficiency of 59.4% at 120 mA cm⁻², and cycling stability of 57% after 10,000 cycles than those of pristine NF and rGO/NF. These results are attributed to the synergy of controllably structured NiCo₂S₄ nanosheets and strong interaction with conductive substrate.