K2Fe(C2O4)2: An Oxalate Cathode for Li/Na-Ion Batteries Exhibiting a Combination of Multielectron Cation and Anion Redox

Atin Pramanik; Alexis G Manche; Moulay Tahar Sougrati; Alan V Chadwick; Philip Lightfoot; A Robert Armstrong

doi:10.1021/acs.chemmater.3c00063

K₂Fe(C₂O₄)₂: An Oxalate Cathode for Li/Na-Ion Batteries Exhibiting a Combination of Multielectron Cation and Anion Redox

Chem Mater. 2023 Mar 13;35(6):2600-2611. doi: 10.1021/acs.chemmater.3c00063. eCollection 2023 Mar 28.

Authors

Atin Pramanik¹, Alexis G Manche^{1

2}, Moulay Tahar Sougrati^{3

4}, Alan V Chadwick^{5

4}, Philip Lightfoot¹, A Robert Armstrong^{1

4

2}

Affiliations

¹ School of Chemistry, University of St. Andrews, Fife, St. Andrews KY16 9ST, United Kingdom.
² The Faraday Institution, Quad One, Harwell Science and Innovation Campus, Didcot OX11 0RA, United Kingdom.
³ Université de Montpellier, 2 Place Eugène Bataillon - CC 1502, 34095 Montpellier Cedex 5, France.
⁴ ALISTORE-ERI, 80039 Amiens Cedex, France.
⁵ School of Physical Sciences, University of Kent, Kent, Canterbury CT2 7NH, United Kingdom.

Abstract

The development of multielectron redox-active cathode materials is a top priority for achieving high energy density with long cycle life in the next-generation secondary battery applications. Triggering anion redox activity is regarded as a promising strategy to enhance the energy density of polyanionic cathodes for Li/Na-ion batteries. Herein, K₂Fe(C₂O₄)₂ is shown to be a promising new cathode material that combines metal redox activity with oxalate anion (C₂O₄ ^2-) redox. This compound reveals specific discharge capacities of 116 and 60 mAh g^-1 for sodium-ion batterie (NIB) and lithium-ion batterie (LIB) cathode applications, respectively, at a rate of 10 mA g^-1, with excellent cycling stability. The experimental results are complemented by density functional theory (DFT) calculations of the average atomic charges.