Jump to main content
Jump to site search
PLANNED MAINTENANCE Close the message box

There will be scheduled maintenance work beginning on Saturday 15th June 2019 at 8:30 am through to Sunday 16th June 2019 at 11:30 pm (BST).

During this time our website may be temporarily affected. We apologise for any inconvenience this might cause and thank you for your patience.


Issue 14, 2019
Previous Article Next Article

Sodium iron sulfate alluaudite solid solution for Na-ion batteries: moving towards stoichiometric Na2Fe2(SO4)3

Author affiliations

Abstract

Thanks to the inductive effect of the sulfate groups, sodium iron sulfate alluaudites display the highest electrode potential amongst the Fe-based compounds studied in sodium-ion batteries. Here, we report the synthetic strategy that has allowed us to obtain the elusive Na2Fe2(SO4)3 stoichiometric compound through a reverse-strike coprecipitation method in organic medium. We experimentally confirm the hypothesis that the stoichiometric compound transforms upon further heat treatment into the previously reported sodium-rich solid solution and an iron sulfate secondary phase. X-ray diffraction and 57Fe Mössbauer spectroscopy do not reveal any striking structure difference between the stoichiometric and Na-rich compounds, in agreement with the current understanding that the instability of the stoichiometric phase is due to the repulsion between Fe2+ ions in the Fe2O10 dimers bridged by sulfate groups. Despite less-than-optimal powder microstructure, electrochemical activity of the stoichiometric phase could be demonstrated through operando X-ray diffraction. These findings are expected to shift attention towards the (near)-stoichiometric compositions, which offer the highest theoretical specific capacities thanks to their optimal Na/Fe ratio.

Graphical abstract: Sodium iron sulfate alluaudite solid solution for Na-ion batteries: moving towards stoichiometric Na2Fe2(SO4)3

Back to tab navigation

Supplementary files

Publication details

The article was received on 04 Jan 2019, accepted on 11 Mar 2019 and first published on 11 Mar 2019


Article type: Paper
DOI: 10.1039/C9TA00116F
J. Mater. Chem. A, 2019,7, 8226-8233

  •   Request permissions

    Sodium iron sulfate alluaudite solid solution for Na-ion batteries: moving towards stoichiometric Na2Fe2(SO4)3

    T. Jungers, A. Mahmoud, C. Malherbe, F. Boschini and B. Vertruyen, J. Mater. Chem. A, 2019, 7, 8226
    DOI: 10.1039/C9TA00116F

Search articles by author

Spotlight

Advertisements