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Issue 18, 2018
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A K2Fe4O7 superionic conductor for all-solid-state potassium metal batteries

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Abstract

A new 3D open-framework potassium ferrite, K2Fe4O7 (1), has been successfully synthesized under hydrothermal conditions. The framework of 1 consists of both FeO6 octahedral and FeO4 tetrahedral units with shared vertices and edges where there are 6- and 3-ring channels parallel to the trigonal a- and c-axes, enabling many highly mobile potassium ions to move quickly through the channels. The K+ ion conductivity of the polycrystalline sample was 5.0 × 10−2 S cm−1 at room temperature. Interestingly, conductivities along the a-axis direction in single crystal K2Fe4O7 reached 3.5 × 102 S cm−1 at 25 °C and 5.0 × 102 S cm−1 at 500 °C with an activation energy of 0.08 eV. The conductor possessed a wide voltage stability up to 5 V vs. K/K+. Using the K2Fe4O7 electrolyte, we demonstrate an all-solid-state potassium metal battery employing a Prussian blue cathode with a high charge/discharge rate of 250C (charge/discharge in 14 s, 1C = 87 mA h g−1).

Graphical abstract: A K2Fe4O7 superionic conductor for all-solid-state potassium metal batteries

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Publication details

The article was received on 09 Feb 2018, accepted on 11 Apr 2018 and first published on 13 Apr 2018


Article type: Paper
DOI: 10.1039/C8TA01418C
Citation: J. Mater. Chem. A, 2018,6, 8413-8418
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    A K2Fe4O7 superionic conductor for all-solid-state potassium metal batteries

    H. Yuan, H. Li, T. Zhang, G. Li, T. He, F. Du and S. Feng, J. Mater. Chem. A, 2018, 6, 8413
    DOI: 10.1039/C8TA01418C

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