title: Induced Rate Performance Enhancement in Off-Stoichiometric Na3+3xV2-x(PO4)3with Potential Applicability as the Cathode for Sodium-Ion Batteries.
abstract: Off-stoichiometric Na3+3xV2-x(PO4)3samples have been prepared by a sol-gel route. X-ray diffraction and XPS revealed the flexibility of the NASICON framework to accommodate these deviations of the stoichiometry; at least for low x values. X-ray photoelectron spectra evidenced the presence of Na4P2O7impurities. The synergic combination of the structural deviations and the presence of Na4P2O7impurities induce a significant improvement of the electrochemical performance and cycling stability at high rates, as compared to the stoichiometric Na3V2(PO4)3sample. The fast kinetic response provided by the induced off-stoichiometry involves a decrease of the cell resistance.
authors.affiliation: Departmento de Química Inorgánica e Ingeniería Química, Instituto Universitario de Química Fina y Nanoquímica, University of Córdoba, Marie Curie Building. Campus de Rabanales, 14071, Córdoba, Spain.
authors.forename: María J
authors.initials: MJ
authors.lastname: Aragón
authors.affiliation: Departmento de Química Inorgánica e Ingeniería Química, Instituto Universitario de Química Fina y Nanoquímica, University of Córdoba, Marie Curie Building. Campus de Rabanales, 14071, Córdoba, Spain.
authors.forename: Pedro
authors.identifier: http://orcid.org/0000-0002-5182-3440
authors.initials: P
authors.lastname: Lavela
authors.affiliation: Departmento de Química Inorgánica e Ingeniería Química, Instituto Universitario de Química Fina y Nanoquímica, University of Córdoba, Marie Curie Building. Campus de Rabanales, 14071, Córdoba, Spain.
authors.forename: Gregorio F
authors.initials: GF
authors.lastname: Ortiz
authors.affiliation: Departmento de Química Inorgánica e Ingeniería Química, Instituto Universitario de Química Fina y Nanoquímica, University of Córdoba, Marie Curie Building. Campus de Rabanales, 14071, Córdoba, Spain.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Alcántara
authors.affiliation: Departmento de Química Inorgánica e Ingeniería Química, Instituto Universitario de Química Fina y Nanoquímica, University of Córdoba, Marie Curie Building. Campus de Rabanales, 14071, Córdoba, Spain.
authors.forename: José L
authors.initials: JL
authors.lastname: Tirado
keywords: battery; electrochemistry; intercalations; sodium; vanadates