Sodium distribution and reaction mechanisms of a Na3V2O2(PO4)2F electrode during use in a sodium-ion battery

DOI: 10.1021/cm5005104

Authors: Neeraj Sharma (The University of New South Wales) , Paula Serras (Universidad del Pais Vasco) , Veronica Palomares (Universidad del Pais Vasco) , Helen E. A. Brand (Australian Synchrotron) , Javier Alonso (Parque Tecnológico de Vizcaya) , Pierre Kubiak (Parque Tecnológico de Álava) , M. Luisa Fdez-Gubieda (Parque Tecnológico de Vizcaya) , Teófilo Rojo (Universidad del Pais Vasco)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chemistry Of Materials , VOL 26 (11) , PAGES 3391 - 3402

State: Published (Approved)
Published: June 2014
Diamond Proposal Number(s): 8577

Abstract: Ambient temperature sodium-ion batteries are emerging as an exciting alternative to commercially dominant lithium-ion batteries for larger scale stationary applications. In order to realize such a sodium-ion battery, electrodes need to be developed, understood, and improved. Here, Na3V2O2(PO4)2F is investigated from the perspective of sodium. Reaction mechanisms for this cathode during battery function include the following: a region comprising at least three phases with subtly varying sodium compositions that transform via two two-phase reaction mechanisms, which appears at the lower potential plateau-like region during both charge and discharge; an extended solid solution region for majority of the cycling process, including most of the higher potential plateau; and a second two-phase region near the highest charge state during charge and between the first and second plateau-like regions during discharge. Notably, the distinct asymmetry in the reaction mechanism, lattice, and volume evolution on charge relative to discharge manifests an interesting question: Is such an asymmetry beneficial for this cathode? These reaction mechanisms are inherently related to sodium evolution, which shows complex behavior between the two sodium crystallographic sites in this compound that in turn mediate the lattice and reaction evolution. Thus, this work relates atomic-level sodium perturbations directly with electrochemical cycling.

Journal Keywords: Batteries; Electrodes; Lattices; Phase transitions; Sodium

Diamond Keywords: Batteries; Sodium-ion

Subject Areas: Chemistry, Energy, Materials


Instruments: B18-Core EXAFS

Other Facilities: Powder Diffraction beamline at Australian Synchrotron

Added On: 04/12/2014 19:18

Discipline Tags:

Energy Storage Energy Physical Chemistry Energy Materials Chemistry Materials Science Chemical Engineering Engineering & Technology

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS) X-ray Absorption Near Edge Structure (XANES)