Urchin and sheaf-like NiCo 2 O 4 nanostructures: Synthesis and electrochemical energy storage application

Abstract

Spinel NiCo2O4 in different morphologies is of current interest in the design and development of electrochemical supercapacitors. In this work, we synthesized two different morphologies of NiCo2O4 by facile hydrothermal method employing CTAB as a soft template and urea as hydrolysis controlling agent. This study has been undertaken to determine the effect of synthesis temperature on the morphology and pseudocapacitance behavior of the NiCo2O4. We find that the temperature variation in the synthesis procedure has a strong effect on the morphology of NiCo2O4, producing urchin-like morphology at 120 °C (NiCoO-120-cal) and sheaf-like morphology at 200 °C (NiCoO-200-cal) with hierarchical porous textures. The effect of morphology on the electrochemical pseudocapacitance behavior was studied by CV, CP and EIS techniques. Both NiCo2O4 samples show higher electrochemical performance than the parent NiO and Co3O4 synthesized under similar conditions. The maximum specific capacitance values obtained for NiCoO-120-cal and NiCoO-200-cal are 636 and 504 F g−1 respectively, at a current density of 0.5 A g−1. The capacitance retention of NiCoO-120-cal and NiCoO-200-cal samples, respectively, are 76% and 69% after 1000 charge–discharge cycles at a current density of 1 A g−1.