Nitrilotriacetic Acid Assisted Preparation of NiCo Bimetallic Nitride/N-Doped Carbon for Supercapacitor Electrode

Abstract

Transition metal nitride has been proved to be an ideal supercapacitor electrode material, and how to synthesize high-performance transition metal nitride-based materials rapidly and stably becomes critical. Here, we complexed the polydentate organic small molecule nitrilotriacetic acid with the transition metals Ni²⁺ and Co²⁺ and nitrided them by pyrolysis of urea. Considering the influence of the structure and morphology of the material on its energy storage properties, we further added sodium citrate to the system to study its effect on the morphology and properties of the complex. The composite (Ni-Co-N/NC) prepared under the optimal sodium citrate addition has a high specific capacitance of 610 F g⁻¹ at a current density of 1 A g⁻¹, and the specific capacitance remains at 84.4% of the initial capacitance after 5000 cycles at 5 A g⁻¹, which shows excellent cycling stability. The maximum energy density of the hybrid capacitor (Ni-Co-N/NC//AC ASC) assembled with activated carbon was 21.1 Wh·kg⁻¹ at a power density of 250 W·kg⁻¹, which shows a promising application in the field of energy storage.