Construction of high-performance electrode materials of NiCo2O4 nanoparticles encapsulated in ultrathin N-doped carbon nanosheets for supercapacitors

Abstract

Highly dispersed nitrogen doped carbon (N–C) is decomposed by 2-methylimidazole (C₄H₆N₂) and is used as a composite material with nickel cobaltite (NiCo₂O₄). The N–C and NiCo₂O₄ composites are obtained by a one-step hydrothermal method and subsequent calcination. In addition, N–C is used to control the morphology and structure of NiCo₂O₄ to obtain excellent capacitor materials. The N–C/NiCo₂O₄ electrode shows an excellent specific capacitance of 157.97 mA h g⁻¹ (1263.75 F g⁻¹) at 1 A g⁻¹. Herein, we successfully develop a N–C/NiCo₂O₄//AC asymmetric supercapacitor (ASC), which is prepared using N–C/NiCo₂O₄ as a cathode coupled with activated carbon (AC) as an anode at a voltage of 1.6 V. The prepared N–C/NiCo₂O₄//AC device shows an excellent volumetric energy density of 66.44 mW h kg⁻¹. The promising performance of N–C/NiCo₂O₄//AC illustrated its potential for portable supercapacitor applications.