Reduced surfactant uptake in three dimensional assemblies of VOx nanotubes improves reversible Li+ intercalation and charge capacity
The relationship between the nanoscale structure of vanadium pentoxide nanotubes and their ability to accommodate Li+ during intercalation/deintercalation is explored. The nanotubes are synthesized using two different precursors through a surfactant-assisted templating method, resulting in standalone VO x (vanadium oxide) nanotubes and also “nano-urchin”. Under highly reducing conditions, where the interlaminar uptake of primary alkylamines is maximized, standalone nanotubes exhibit near-perfect scrolled layers and long-range structural order even at the molecular level. Under less reducing conditions, the degree of amine uptake is reduced due to a lower density of V4+ sites and less V2O5 is functionalized with adsorbed alkylammonium cations. This is typical of the nano-urchin structure. High-resolution TEM studies revealed the unique observation of nanometer-scale nanocrystals of pristine unreacted V2O5 throughout the length of the nanotubes in the nano-urchin. Electrochemical intercalation studies revealed that the very well ordered xerogel-based nanotubes exhibit similar specific capacities (235 mA h g−1) to Na+-exchange nanorolls of VOx (200 mA h g−1). By comparison, the theoretical maximum value is reported to be 240 mA h g−1. The VOTPP-based nanotubes of the nano-urchin 3D assemblies, however, exhibit useful charge capacities exceeding 437 mA h g−1, which is a considerable advance for VOx based nanomaterials and one of the highest known capacities for Li+ intercalated laminar vanadates.
PublisherWiley and Sons Ltd.,
Rights© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. This is the pre-peer reviewed version of the following article: O'DWYER, C., LAVAYEN, V., TANNER, D. A., NEWCOMB, S. B., BENAVENTE, E., GONZÁLEZ, G. & TORRES, C. M. S. 2009. Reduced Surfactant Uptake in Three Dimensional Assemblies of VOx Nanotubes Improves Reversible Li+ Intercalation and Charge Capacity. Advanced Functional Materials, 19, 1736-1745., which has been published in final form at http://dx.doi.org/10.1002/adfm.200801107
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