Yolk–shell Ni–Co bimetallic nitride/oxide heterostructures as high‐performance electrode of all‐solid‐state supercapacitor

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.