Synthesis of urchin-like MnCo2O4 nanospheres as electrode material for supercapacitors

Abstract

The morphology of MnCo₂O₄ has a significant effect on the electrochemical performance. In this paper, urchin-like MnCo₂O₄ nanospheres was successfully fabricated by a simple hydrothermal process and post-annealing treatment. The effects of addition of surfactant (Hexadecy ltrimethyl ammonium bromide) on the crystal structure, surface morphology and electrochemical performance of MnCo₂O₄ have been investigated. The results show that all the synthesized manganese cobalt oxides are composed of cubic spinel MnCo₂O₄. The addition of surfactant leads to the change of the morphology of MnCo₂O₄ from nanoarray to urchin-like nanospheres and increases the specific surface area, which is beneficial to improve the electrochemical performance of the MnCo₂O₄ electrode. The electrochemical test reveals that the urchin-like MnCo₂O₄ nanospheres delivered a high specific capacity of 2019 F/g at a 1 A/g and 1144 F/g at 5 A/g, respectively. The specific capacity of MnCo₂O₄ electrode reaches 512 F/g at 10 A/g and retains 96 % of the initial capacity after 2000 cycles at 10 A/g, which maintains an extraordinary cycling performance. In addition, an asymmetric supercapacitor (MnCo₂O₄//AC) with urchin-like MnCo₂O₄ nanospheres as a cathode and activated carbon (AC) as an anode was also assembled. Impressively, the assembled MnCo₂O₄//AC asymmetric supercapacitor exhibits a high energy density of 69 Wh/kg at a power density of 793 W/kg. The above research shows that the urchin-like MnCo₂O₄ nanospheres synthesized by adding surfactants are expected to be excellent high-performance energy storage electrode materials, which provides a new strategy for the synthesis of high-capacity nanoelectrode materials.