title: A fractal-like electrode based on double-wall nanotubes of anatase exhibiting improved electrochemical behaviour in both lithium and sodium batteries.
abstract: An anatase nanotube array has been prepared with a special morphology: two concentric walls and a very small central cavity. The method used here to achieve the double-wall structure is a single-step anodization process under a voltage ramp. Thanks to this nanostructure, which is equivalent to a fractal electrode, the electrochemical behaviour is improved, and the specific capacity is higher in both lithium and sodium cells due to pseudocapacitance. The double-wall structure of the nanotube enhances the surface of TiO2 being in contact with the electrolyte solution, thus allowing an easy penetration of the alkali ions into the electrode active material. The occurrence of sodium titanate in the electrode material after electrochemical reaction with sodium is studied by using EPR, HRTEM and NMR experiments.
authors.affiliation: Laboratorio de Química Inorgánica, Campus universitario de Rabanales, Edificio C3, Universidad de Córdoba, 14071 Córdoba, Spain. iq2alror@uco.es.
authors.forename: José R
authors.initials: JR
authors.lastname: González
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Zhecheva
authors.forename: Radostina
authors.initials: R
authors.lastname: Stoyanova
authors.forename: Diana
authors.initials: D
authors.lastname: Nihtianova
authors.forename: Pavel
authors.initials: P
authors.lastname: Markov
authors.forename: Régis Ravelle
authors.initials: RR
authors.lastname: Chapuis
authors.forename: Ricardo
authors.initials: R
authors.lastname: Alcántara
authors.forename: Francisco
authors.initials: F
authors.lastname: Nacimiento
authors.forename: José L
authors.initials: JL
authors.lastname: Tirado
authors.forename: Gregorio F
authors.initials: GF
authors.lastname: Ortiz