Electrochemical lithium storage kinetics of self-organized nanochannel niobium oxide electrodes

• Oriented nanochannel Nb2O5 films were prepared by anodization.
• Electrochemical lithium storage kinetics was investigated using cyclic voltammetry.
• Film morphology significantly affects the Li insertion and extraction kinetics.
• Electronic transport is a major limiting factor for reversible lithium storage.
• For improved kinetics, the use of a conductive material coating is suggested.

Oriented nanochannel niobium pentoxide (Nb2O5) films with different geometries were prepared via the anodization of Nb foils, and the electrochemical lithium storage kinetics for batteries and hybrid supercapacitors were investigated using cyclic voltammetry. The morphology and crystal structure of the nanoporous Nb2O5 films were examined by X-ray diffraction analysis and scanning and transmission electron microscopies. Analyses of the cyclic voltammograms indicated that the film morphology, including the pore size and film thickness, significantly affects the Li insertion and extraction kinetics. Furthermore, electronic transport through the nanochannel film appears to become a major limiting factor for reversible lithium storage as both the potential sweep speed and film thickness increase. To enhance the electrochemical lithium storage kinetics in the ordered nanochannel Nb2O5 films, the use of a conductive material coating and phase transformation are suggested.