Yolk–shell Ni–Co bimetallic nitride/oxide (NiCoNO) heterostructures, derived from NiCo-glycerate solid spheres, demonstrates excellent electrochemical performance as supercapacitor electrode.

Hierarchical core–shell structure is benefit for the fast diffusion and bulk storage of electron/ion while metal nitrides (MN) exhibit metal-like behavior with excellent conductivity. Herein, nickel cobalt glycerate solid spheres (NiCo-G) and nickel cobalt glycerate yolk–shell structure (NiCo-GYS) were successfully synthesized via solvothermal reactions, accompanied by annealing using urea as a cheap and convenient nitrogen source to obtain metal nitride/bimetallic oxide core–shell heterostructure (NiCoNO). Excellent specific capacitance of 1878 F g⁻¹ at 1 A g⁻¹ is displayed by the prepared NiCoNO. Amazingly, the distinct core–shell construction guarantees high stability during the charge/discharge operation. NiCoNO maintains an 83.9% specific capacitance after 5000 cycles at 10 A g⁻¹. Furthermore, the all-solid-state hybrid supercapacitor was assembled using NiCoNO cathode and active carbon (AC) anode components. The device has an excellent capacitive retention rate of 81.1% after 5000 cycles at 10 A g⁻¹ and a good energy density of 64.2 Wh kg⁻¹ at a power density of 900 Wh kg⁻¹. A light-emitting diode (LED) bulb can be lighted for 3 min, indicating the promising practical application prospect of the supercapacitor.