Incorporation of homogeneous Co3O4 into a nitrogen-doped carbon aerogel via a facile in situ synthesis method: implications for high performance asymmetric supercapacitors

Abstract

A novel high-performance electrode material, nitrogen-doped carbon aerogel/cobalt oxide (NCA/Co₃O₄) material, was prepared by a facile, one step and in situ coating method, followed by a freeze-drying process. The effects of different amounts of Co₃O₄ on the structural properties, specific surface areas, elemental compositions and electrochemical performance of the composite electrodes were investigated. Consequently, the electrode with 75% mass content of Co₃O₄ exhibited excellent electrochemical performance, in particular, a high specific capacitance of 616 F g⁻¹ at a current density of 1 A g⁻¹, excellent rate capability (445 F g⁻¹ at 20 A g⁻¹) and outstanding cycle performance. In addition, the asymmetric supercapacitor assembled with NCA/Co₃O₄-3 and NCA electrodes could be cycled in a high voltage range of 1.5 V and deliver a maximum energy density of 33.43 W h kg⁻¹ at a power density of 375 W kg⁻¹. The enhanced electrochemical performance is attributed to the complementary contributions of the 3D interconnected porous structure and the efficient pseudocapacitance of the uniformly dispersed Co₃O₄ nanoparticles. The preparation method offers a new fabrication strategy to in situ fabricate carbon-supported metal oxide electrodes for high-performance energy storage applications.