uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Defect Thermodynamics in Nonstoichiometric Alluaudite-Based Polyanionic Materials for Na-Ion Batteries
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Indian Inst Technol Indore, Discipline Phys, Indore 453552, Madhya Pradesh, India.ORCID iD: 0000-0002-6765-2084
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden.ORCID iD: 0000-0003-1231-9994
2019 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 36, p. 32856-32868Article in journal (Refereed) Published
Abstract [en]

Sodium iron sulfate in the form of alluaudite Na2+2xFe2-x(SO4)(3) (or NFSx) has emerged as one of the most promising cathodes for Na-ion batteries due to its highest Fe2+/3+ redox potential, low cost, sustainability, and high rate capability. Unlike most of the other cathodes, NFSx generally crystalizes in its nonstoichiometric form with partial Na substitution for Fe sites and contains a small amount of impurities. However, profound explanations behind this inherent behavior including others, like phase stability, configurational structure, and defect formation are still ambiguous. We therefore performed first-principles calculations combined with a random swapping method to determine the minimum energy configurations of NFSx (with x = 0, 0.25, and 0.5) and find a correlation between the Na distribution pattern and energetics in which the site preference for Na+ ion is in a sequence of Na4 > Na1 > Na2 > Na3. Our result points out that the nonstoichiometry cannot be properly described under the framework of primitive structures. Moreover, we investigated phase stability diagrams and defect formations based on thermodynamic criteria. Our predicted phase diagrams can explain the inevitable impurity precipitation, which can be reduced as x diminishes. Defect formation analysis indicates an unlikely formation of channel blockage and identifies the dominant formation of Fe-Na + V-Na and Na-i + Na-Fe complexes. While the former can become spontaneous in a Na-deficient environment, the latter occurs mainly in NFS0 and accommodates the presence of nonstoichiometry.

Place, publisher, year, edition, pages
2019. Vol. 11, no 36, p. 32856-32868
Keywords [en]
density functional theory, batteries, chemical potentials, nonstoichiometry, minimum energy configurations, defect formation energies, phase diagrams, impurities
National Category
Condensed Matter Physics Materials Chemistry
Identifiers
URN: urn:nbn:se:uu:diva-396667DOI: 10.1021/acsami.9b07027ISI: 000486360500028PubMedID: 31353884OAI: oai:DiVA.org:uu-396667DiVA, id: diva2:1368600
Funder
Swedish Research CouncilStandUpSwedish Research CouncilAvailable from: 2019-11-07 Created: 2019-11-07 Last updated: 2019-11-07Bibliographically approved

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full textPubMed

Authority records BETA

Watcharatharapong, TeeraphatChakraborty, SudipAhuja, Rajeev

Search in DiVA

By author/editor
Watcharatharapong, TeeraphatChakraborty, SudipAhuja, Rajeev
By organisation
Materials Theory
In the same journal
ACS Applied Materials and Interfaces
Condensed Matter PhysicsMaterials Chemistry

Search outside of DiVA

GoogleGoogle Scholar

doi
pubmed
urn-nbn

Altmetric score

doi
pubmed
urn-nbn
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf