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Electrochemical insertion of potassium ions in Na4Fe3(PO4)2P2O7 mixed phosphate

Senthilkumar, B and Murugesan, C and Sada, K and Barpanda, P (2020) Electrochemical insertion of potassium ions in Na4Fe3(PO4)2P2O7 mixed phosphate. In: Journal of Power Sources, 480 .

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Official URL: https://dx.doi.org/10.1016/j.jpowsour.2020.228794


Potassium-ion batteries (KIBs) can offer high-voltage performance and energy density similar to lithium-ion batteries with the added advantages of elemental abundance, materials economy, and efficient K+ intercalation due to smaller radius of solvated ions. This nascent field offers ample room to exploit open framework polyanionic compounds as efficient cathode materials. Due to similar ionic size, Na-based compounds can be employed as suitable cathodes for KIBs. In this work, iron-based mixed phosphate Na4Fe3(PO4)2P2O7 is demonstrated as a robust 3.0 V cathode for potassium-ion batteries. The in-situ carbon coated nanoscale Na4Fe3(PO4)2P2O7 cathode delivers a discharge capacity of ~120 mAh g�1 (i.e., 94 of its theoretical capacity) with excellent capacity retention and rate kinetics. With its three-dimensional open framework having multiple alkali sites, Na4-xFe3(PO4)2P2O7 undergoes a solid-solution Fe3+/Fe2+ redox mechanism acting as an efficient host for K+ (de)insertion. It forms the best Fe-based phospho-polyanionic cathode for potassium-ion batteries. A full cell comprising Na4-xFe3(PO4)2P2O7 cathode and graphite anode demonstrates the potential future application in KIBs. It marks the first demonstration of Na-based mixed polyanionic phosphates as insertion hosts for KIBs, which can be extended to various polyanionic insertion materials. © 2020 Elsevier B.V.

Item Type: Journal Article
Publication: Journal of Power Sources
Publisher: Elsevier B.V.
Additional Information: The copyright of this article belongs to Elsevier B.V.
Keywords: Cathodes; Ions; Lithium-ion batteries; Potassium; Sodium compounds, Capacity retention; Discharge capacities; Electrochemical insertion; Elemental abundance; Future applications; Insertion materials; Redox mechanism; Theoretical capacity, Iron compounds
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Date Deposited: 22 Sep 2020 07:14
Last Modified: 22 Sep 2020 07:14
URI: http://eprints.iisc.ac.in/id/eprint/66510

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