Carbon Nanocoil-Supported Three-Dimensional Structure of Nickel–Cobalt Nitrides as the Electrode Material for Supercapacitors

Hybrid nanostructures enriched in a large number of electroactive sites are fascinating electrode materials for the high-performance supercapacitors (SCs). Transition-metal nitrides attract a lot of attention due to their excellent electrochemical performance for energy-related applications. Herein, a three-dimensional (3D) structure is engineered by tailoring nickel–cobalt nitride (NiCo–N) nanoparticles anchored on carbon nanocoils/nickel foam (CNCs/NF) substrates through a facile solvothermal reaction and subsequent annealing under an NH3 atmosphere. The 3D CNCs/NF scaffolds offer a high surface area for the growth of NiCo–N nanoparticles, consequently resulting in the increased electroactive sites for redox reactions. The optimal binder-free hybrid composite electrode (NiCo–N/CNCs/NF at 600 °C) yields a specific capacitance of 5235 F g–1 at 1 A g–1 and a rate capability of 86% at 50 A g–1, and 95.6% capacitance is retained after 3000 cycles. This remarkable electrochemical performance solely corresponds to the synergistic effect of NiCo–N and CNCs/NF, thereby achieving efficacious redox reactions and desirable electronic conductivity. Moreover, the appealing electrochemical performance of the NiCo–N/CNCs/NF hybrid composite paves the way as a promising candidate for SC electrodes.