Atomic layer deposition of vanadium oxide on carbon nanotubes for high-power supercapacitor electrodes

Vanadium oxides may offer high pseudocapacitance but limited electrical conductivity and specific surface area. Atomic layer deposition allowed uniform deposition of smooth nanostructured vanadium oxide coatings on the surface of multi-walled carbon nanotube (MWCNT) electrodes, thus offering a novel route for the formation of binder-free flexible composite electrode fabric for supercapacitor applications with large thickness, controlled porosity, greatly improved electrical conductivity and cycle stability. Electrochemical measurements revealed stable performance of the selected MWCNT-vanadium oxide electrodes and remarkable capacitance of up to ∼1550 F g −1 per active mass of the vanadium oxide and up to ∼600 F g −1 per mass of the composite electrode, significantly exceeding specific capacitance of commercially used activated carbons (100-150 F g −1 ). Electrochemical performance of the oxide layers was found to strongly depend on the coating thickness. Uniform atomic layer deposition (ALD) of vanadium oxide coatings on the surface of carbon nanotube supercapacitor electrodes resulted in high values of electrode capacitance (~600 F g −1 ) combined with the device's high power capability.