In Situ Studies of Fe4+ Stability in β-Li3Fe2(PO4)3 Cathodes for Li Ion Batteries

Ane Sælland Christiansen; Rune E. Johnsen; Poul Norby; Cathrine Frandsen; Steen Mørup; Søren Højgaard Jensen; Kent Kammer Hansen; Peter Holtappels

doi:10.1149/2.0141504jes

In Situ Studies of Fe⁴⁺ Stability in β-Li₃Fe₂(PO₄)₃ Cathodes for Li Ion Batteries

Ane Sælland Christiansen, Rune E. Johnsen, Poul Norby, Cathrine Frandsen, Steen Mørup, Søren Højgaard Jensen, Kent Kammer Hansen, Peter Holtappels

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Abstract

In commercial Fe-based batteries the Fe2+/Fe3+ oxidation states are used, however by also utilizing the Fe4+ oxidation state, intercalation of up to two Li ions per Fe ion could be possible. In this study, we investigate whether Fe4+ can be formed and stabilized in β-Li3Fe2(PO4)3. The work includes in situ synchrotron X-ray powder diffraction studies (XRPD) during charging of β-Li3Fe2(PO4)3 up to 5.0 V vs. Li/Li+. A novel capillary-based micro battery cell for in situ XRPD has been designed for this. During charge, a plateau at 4.5 V was found and a small contraction in volume was observed, indicating some Li ion extraction. The volume change of the rhombohedral unit cell is anisotropic, with a decrease in the a parameter and an increase in the c parameter during the Li ion extraction. Unfortunately, no increased discharge capacity was observed and Mössbauer spectroscopy showed no evidence of Fe4+ formation. Oxidation of the organic electrolyte is inevitable at 4.5 V but this alone cannot explain the volume change. Instead, a reversible oxygen redox process (O2− → O−) could possibly explain and charge compensate for the reversible extraction of lithium ions from β-Li3Fe2(PO4)3.

Original language	English
Journal	Journal of The Electrochemical Society
Volume	162
Issue number	4
Pages (from-to)	A531-A537
ISSN	0013-4651
DOIs	https://doi.org/10.1149/2.0141504jes
Publication status	Published - 2015

Bibliographical note

Erratum in Electrochemical Society. Journal, 2015, 162(6) p. X11: Throughout this paper, the prefix “β-” has been used incorrectly to indicate the rhombohedral phase of Li3Fe2(PO4)3. The material studied in the paper is exclusively the rhombohedral phase and all instances of “β-Li3Fe2(PO4)3” should be replaced with “Li3Fe2(PO4)3.”

Keywords

Batteries and Energy Storage
A

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title = "In Situ Studies of Fe4+ Stability in β-Li3Fe2(PO4)3 Cathodes for Li Ion Batteries",

abstract = "In commercial Fe-based batteries the Fe2+/Fe3+ oxidation states are used, however by also utilizing the Fe4+ oxidation state, intercalation of up to two Li ions per Fe ion could be possible. In this study, we investigate whether Fe4+ can be formed and stabilized in β-Li3Fe2(PO4)3. The work includes in situ synchrotron X-ray powder diffraction studies (XRPD) during charging of β-Li3Fe2(PO4)3 up to 5.0 V vs. Li/Li+. A novel capillary-based micro battery cell for in situ XRPD has been designed for this. During charge, a plateau at 4.5 V was found and a small contraction in volume was observed, indicating some Li ion extraction. The volume change of the rhombohedral unit cell is anisotropic, with a decrease in the a parameter and an increase in the c parameter during the Li ion extraction. Unfortunately, no increased discharge capacity was observed and M{\"o}ssbauer spectroscopy showed no evidence of Fe4+ formation. Oxidation of the organic electrolyte is inevitable at 4.5 V but this alone cannot explain the volume change. Instead, a reversible oxygen redox process (O2− → O−) could possibly explain and charge compensate for the reversible extraction of lithium ions from β-Li3Fe2(PO4)3.",

keywords = "Batteries and Energy Storage, A",

author = "Christiansen, {Ane S{\ae}lland} and Johnsen, {Rune E.} and Poul Norby and Cathrine Frandsen and Steen M{\o}rup and Jensen, {S{\o}ren H{\o}jgaard} and {Kammer Hansen}, Kent and Peter Holtappels",

note = "Erratum in Electrochemical Society. Journal, 2015, 162(6) p. X11: Throughout this paper, the prefix “β-” has been used incorrectly to indicate the rhombohedral phase of Li3Fe2(PO4)3. The material studied in the paper is exclusively the rhombohedral phase and all instances of “β-Li3Fe2(PO4)3” should be replaced with “Li3Fe2(PO4)3.”",

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doi = "10.1149/2.0141504jes",

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TY - JOUR

T1 - In Situ Studies of Fe4+ Stability in β-Li3Fe2(PO4)3 Cathodes for Li Ion Batteries

AU - Christiansen, Ane Sælland

AU - Johnsen, Rune E.

AU - Norby, Poul

AU - Frandsen, Cathrine

AU - Mørup, Steen

AU - Jensen, Søren Højgaard

AU - Kammer Hansen, Kent

AU - Holtappels, Peter

N1 - Erratum in Electrochemical Society. Journal, 2015, 162(6) p. X11: Throughout this paper, the prefix “β-” has been used incorrectly to indicate the rhombohedral phase of Li3Fe2(PO4)3. The material studied in the paper is exclusively the rhombohedral phase and all instances of “β-Li3Fe2(PO4)3” should be replaced with “Li3Fe2(PO4)3.”

PY - 2015

Y1 - 2015

N2 - In commercial Fe-based batteries the Fe2+/Fe3+ oxidation states are used, however by also utilizing the Fe4+ oxidation state, intercalation of up to two Li ions per Fe ion could be possible. In this study, we investigate whether Fe4+ can be formed and stabilized in β-Li3Fe2(PO4)3. The work includes in situ synchrotron X-ray powder diffraction studies (XRPD) during charging of β-Li3Fe2(PO4)3 up to 5.0 V vs. Li/Li+. A novel capillary-based micro battery cell for in situ XRPD has been designed for this. During charge, a plateau at 4.5 V was found and a small contraction in volume was observed, indicating some Li ion extraction. The volume change of the rhombohedral unit cell is anisotropic, with a decrease in the a parameter and an increase in the c parameter during the Li ion extraction. Unfortunately, no increased discharge capacity was observed and Mössbauer spectroscopy showed no evidence of Fe4+ formation. Oxidation of the organic electrolyte is inevitable at 4.5 V but this alone cannot explain the volume change. Instead, a reversible oxygen redox process (O2− → O−) could possibly explain and charge compensate for the reversible extraction of lithium ions from β-Li3Fe2(PO4)3.

AB - In commercial Fe-based batteries the Fe2+/Fe3+ oxidation states are used, however by also utilizing the Fe4+ oxidation state, intercalation of up to two Li ions per Fe ion could be possible. In this study, we investigate whether Fe4+ can be formed and stabilized in β-Li3Fe2(PO4)3. The work includes in situ synchrotron X-ray powder diffraction studies (XRPD) during charging of β-Li3Fe2(PO4)3 up to 5.0 V vs. Li/Li+. A novel capillary-based micro battery cell for in situ XRPD has been designed for this. During charge, a plateau at 4.5 V was found and a small contraction in volume was observed, indicating some Li ion extraction. The volume change of the rhombohedral unit cell is anisotropic, with a decrease in the a parameter and an increase in the c parameter during the Li ion extraction. Unfortunately, no increased discharge capacity was observed and Mössbauer spectroscopy showed no evidence of Fe4+ formation. Oxidation of the organic electrolyte is inevitable at 4.5 V but this alone cannot explain the volume change. Instead, a reversible oxygen redox process (O2− → O−) could possibly explain and charge compensate for the reversible extraction of lithium ions from β-Li3Fe2(PO4)3.

KW - Batteries and Energy Storage

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U2 - 10.1149/2.0141504jes

DO - 10.1149/2.0141504jes

M3 - Journal article

SN - 0013-4651

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JO - Journal of The Electrochemical Society

JF - Journal of The Electrochemical Society

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