Generic Synthesis of Carbon Nanotube Branches on Metal Oxide Arrays Exhibiting Stable High-Rate and Long-Cycle Sodium-Ion Storage

A new and generic strategy to construct interwoven carbon nanotube (CNT) branches on various metal oxide nanostructure arrays (exemplified by V₂O₃ nanoflakes, Co₃O₄ nanowires, Co₃O₄–CoTiO₃ composite nanotubes, and ZnO microrods), in order to enhance their electrochemical performance, is demonstrated for the first time. In the second part, the V₂O₃/CNTs core/branch composite arrays as the host for Na⁺ storage are investigated in detail. This V₂O₃/CNTs hybrid electrode achieves a reversible charge storage capacity of 612 mAh g⁻¹ at 0.1 A g⁻¹ and outstanding high-rate cycling stability (a capacity retention of 100% after 6000 cycles at 2 A g⁻¹, and 70% after 10 000 cycles at 10 A g⁻¹). Kinetics analysis reveals that the Na⁺ storage is a pseudocapacitive dominating process and the CNTs improve the levels of pseudocapacitive energy by providing a conductive network.