Hierarchical CNT@NiCo2O4 core–shell hybrid nanostructure for high-performance supercapacitors

Abstract

The mass integration of electrochemically active materials on nanosized conductive fillers is a promising strategy to achieve an ideal electrode structure for energy storage devices. In this research, a one-dimensional CNT@NiCo₂O₄ nanosheet core–shell structural nanocable was constructed by a facile chemical co-deposition route combined with post-calcination in air. The subsequent thermal treatment led to the transformation of the hydroxide nanosheet precursor to NiCo₂O₄ nanosheets, during which process the overall morphology and structure were well retained. By selecting CNTs as conductive support for ultra-thin NiCo₂O₄ nanosheets, a high-performance electrode for supercapacitors was obtained. Notably, the as-prepared CNT@NiCo₂O₄ nanocables have a high capacitance of 1038 F g⁻¹ at a current density of 0.5 A g⁻¹. Furthermore, the specific capacitance of the product was almost 100% retained after 1000 cycles, which indicates excellent structural and cycling stability. More importantly, a relatively high mass loading of active materials on CNTs was also achieved, making the practical application of such electrode materials possible. Consequently, this CNT@NiCo₂O₄ nanocable is a promising electrode for high-performance supercapacitors.