A Facile Route to Metal Oxides/Single-Walled Carbon Nanotube Macrofilm Nanocomposites for Energy Storage

Nanocomposites consisting of transition-metal oxides and carbon nanomaterials with a desired size and structure are highly demanded for high-performance energy storage devices. Here, a facile two-step and cost-efficient approach relying on directly thermal treatment of chemical vapor deposition products is developed as a general synthetic method to prepare a family of metal oxides [MxOy (M = Fe, Co, Ni)]/single-walled carbon nanotube (SWNT) macrofilm nanocomposites. The MxOy nanoparticles obtained are of 3–17 nm in diameter and homogeneously anchor on the free-standing SWNT macrofilms. NiO/SWNT also exhibits a high-specific capacitance of 400 F g−1 and fast charge-transfer Faradaic redox reactions to achieve asymmetric supercapacitors with a high power and energy density. All MxOy/SWNT nanocomposites could deliver a high capacity beyond 1000 mAh g−1 and show excellent cycling stability for lithium-ion batteries. The impressive results demonstrate the promise for energy storage devices and the general approach may pave the way to synthesize other functional nanocomposites.