A reinvestigation of Na2Fe2(C2O4)2H2O: an iron-based positive electrode for secondary batteries

Wenjiao Yao, Moulay-Tahar Sougrati, Khang Hoang, Jianing Hui, Philip Lightfoot, A. Robert Armstrong

Research output: Contribution to journalArticlepeer-review

Abstract

We have reinvestigated the polyanionic compound Na2Fe2(C2O4)3·2H2O, previously reported to be electrochemically inactive in lithium-ion batteries (LIBs), as a positive electrode for sodium-ion batteries (NIBs). The present study demonstrates that it is capable of delivering a reversible capacity close to its theoretical value (117 mAhg–1) with three redox plateaus at 2.9, 3.3 and 3.6 V vs. Na/Na+ in the potential range 1.7–4.2 V. The obtained energy density of 326 WhKg–1 is among the highest of all reported polyanionic cathodes in NIBs. The origin of the electrochemical activity can be traced back to the electronic structure of the compound and the low migration energy barrier of the alkali ion observed in first-principles density-functional theory calculations.
Original languageEnglish
Pages (from-to)9095-9101
JournalChemistry of Materials
Volume29
Issue number21
Early online date4 Oct 2017
DOIs
Publication statusPublished - 14 Nov 2017

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