Redox effect of Fe2+/Fe3+ in iron phosphates for enhanced electrocatalytic activity in Li-O2 batteries

Gwang Hee Lee; Yoon Seon Kim; Dong Wan Kim

doi:10.1016/j.cej.2020.124294

Redox effect of Fe²⁺/Fe³⁺ in iron phosphates for enhanced electrocatalytic activity in Li-O₂ batteries

Gwang Hee Lee, Yoon Seon Kim, Dong Wan Kim

Research output: Contribution to journal › Article › peer-review

31 Citations (Scopus)

Abstract

FePO₄ and porous Fe₂P₂O₇ laundry-ball-like nanostructures (FePO₄ LBs and p-Fe₂P₂O₇ LBs, respectively) were prepared to investigate their functionalities as oxygen-electrode (O₂-electrode) electrocatalysts in Li–O₂ batteries. These structures were synthesized in two steps, via hydrothermal and thermal reactions. FePO₄ LBs were synthesized through thermal dehydrogenation of as-prepared FePO₄·2H₂O precursors (FePO₄·2H₂O → FePO₄ + 2H₂O), and p-Fe₂P₂O₇ LBs were synthesized through thermochemical reduction of same precursors under an H₂ atmosphere (2FePO₄·2H₂O + H₂ → Fe₂P₂O₇ + 5H₂O). As an O₂-electrode electrocatalyst in Li–O₂ cells, p-Fe₂P₂O₇ LBs exhibited a higher discharge capacity (30,000 mA h g_catalyst^–1 at a current density of 500 mA g_catalyst^–1), higher reversibility (300 cycles at a current rate of 500 mA g_catalyst^–1), and lower voltage gap, compared to FePO₄ LBs. These superior performances of p-Fe₂P₂O₇ LBs result from the Fe²⁺/Fe³⁺ redox effect and porous structure, which enhance the oxygen reduction or evolution reaction activities.

Original language	English
Article number	124294
Journal	Chemical Engineering Journal
Volume	388
DOIs	https://doi.org/10.1016/j.cej.2020.124294
Publication status	Published - 2020 May 15

Bibliographical note

Funding Information:
This work was supported by a Korea University Grant, South Korea and, the National Research Foundation of Korea (NRF) Grant, South Korea funded by the Ministry of Science, ICT, and Future Planning [NRF-2017R1C1B2004869, 2019R1A2B5B02070203, and 2018M3D1A1058744], South Korea.

Publisher Copyright:
© 2020 Elsevier B.V.

Keywords

Electrocatalysts
Fe/Fe redox effect
Iron phosphates
Li–O battery
Thermal reaction

ASJC Scopus subject areas

General Chemistry
Environmental Chemistry
General Chemical Engineering
Industrial and Manufacturing Engineering

Access to Document

10.1016/j.cej.2020.124294

Cite this

@article{54005a85d11b4e8888f02d1545b4514f,

title = "Redox effect of Fe2+/Fe3+ in iron phosphates for enhanced electrocatalytic activity in Li-O2 batteries",

abstract = "FePO4 and porous Fe2P2O7 laundry-ball-like nanostructures (FePO4 LBs and p-Fe2P2O7 LBs, respectively) were prepared to investigate their functionalities as oxygen-electrode (O2-electrode) electrocatalysts in Li–O2 batteries. These structures were synthesized in two steps, via hydrothermal and thermal reactions. FePO4 LBs were synthesized through thermal dehydrogenation of as-prepared FePO4·2H2O precursors (FePO4·2H2O → FePO4 + 2H2O), and p-Fe2P2O7 LBs were synthesized through thermochemical reduction of same precursors under an H2 atmosphere (2FePO4·2H2O + H2 → Fe2P2O7 + 5H2O). As an O2-electrode electrocatalyst in Li–O2 cells, p-Fe2P2O7 LBs exhibited a higher discharge capacity (30,000 mA h gcatalyst–1 at a current density of 500 mA gcatalyst–1), higher reversibility (300 cycles at a current rate of 500 mA gcatalyst–1), and lower voltage gap, compared to FePO4 LBs. These superior performances of p-Fe2P2O7 LBs result from the Fe2+/Fe3+ redox effect and porous structure, which enhance the oxygen reduction or evolution reaction activities.",

keywords = "Electrocatalysts, Fe/Fe redox effect, Iron phosphates, Li–O battery, Thermal reaction",

author = "Lee, {Gwang Hee} and {Seon Kim}, Yoon and Kim, {Dong Wan}",

note = "Funding Information: This work was supported by a Korea University Grant, South Korea and, the National Research Foundation of Korea (NRF) Grant, South Korea funded by the Ministry of Science, ICT, and Future Planning [NRF-2017R1C1B2004869, 2019R1A2B5B02070203, and 2018M3D1A1058744], South Korea. Publisher Copyright: {\textcopyright} 2020 Elsevier B.V.",

year = "2020",

month = may,

day = "15",

doi = "10.1016/j.cej.2020.124294",

language = "English",

volume = "388",

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AU - Lee, Gwang Hee

AU - Seon Kim, Yoon

AU - Kim, Dong Wan

N1 - Funding Information: This work was supported by a Korea University Grant, South Korea and, the National Research Foundation of Korea (NRF) Grant, South Korea funded by the Ministry of Science, ICT, and Future Planning [NRF-2017R1C1B2004869, 2019R1A2B5B02070203, and 2018M3D1A1058744], South Korea. Publisher Copyright: © 2020 Elsevier B.V.

PY - 2020/5/15

Y1 - 2020/5/15

N2 - FePO4 and porous Fe2P2O7 laundry-ball-like nanostructures (FePO4 LBs and p-Fe2P2O7 LBs, respectively) were prepared to investigate their functionalities as oxygen-electrode (O2-electrode) electrocatalysts in Li–O2 batteries. These structures were synthesized in two steps, via hydrothermal and thermal reactions. FePO4 LBs were synthesized through thermal dehydrogenation of as-prepared FePO4·2H2O precursors (FePO4·2H2O → FePO4 + 2H2O), and p-Fe2P2O7 LBs were synthesized through thermochemical reduction of same precursors under an H2 atmosphere (2FePO4·2H2O + H2 → Fe2P2O7 + 5H2O). As an O2-electrode electrocatalyst in Li–O2 cells, p-Fe2P2O7 LBs exhibited a higher discharge capacity (30,000 mA h gcatalyst–1 at a current density of 500 mA gcatalyst–1), higher reversibility (300 cycles at a current rate of 500 mA gcatalyst–1), and lower voltage gap, compared to FePO4 LBs. These superior performances of p-Fe2P2O7 LBs result from the Fe2+/Fe3+ redox effect and porous structure, which enhance the oxygen reduction or evolution reaction activities.

AB - FePO4 and porous Fe2P2O7 laundry-ball-like nanostructures (FePO4 LBs and p-Fe2P2O7 LBs, respectively) were prepared to investigate their functionalities as oxygen-electrode (O2-electrode) electrocatalysts in Li–O2 batteries. These structures were synthesized in two steps, via hydrothermal and thermal reactions. FePO4 LBs were synthesized through thermal dehydrogenation of as-prepared FePO4·2H2O precursors (FePO4·2H2O → FePO4 + 2H2O), and p-Fe2P2O7 LBs were synthesized through thermochemical reduction of same precursors under an H2 atmosphere (2FePO4·2H2O + H2 → Fe2P2O7 + 5H2O). As an O2-electrode electrocatalyst in Li–O2 cells, p-Fe2P2O7 LBs exhibited a higher discharge capacity (30,000 mA h gcatalyst–1 at a current density of 500 mA gcatalyst–1), higher reversibility (300 cycles at a current rate of 500 mA gcatalyst–1), and lower voltage gap, compared to FePO4 LBs. These superior performances of p-Fe2P2O7 LBs result from the Fe2+/Fe3+ redox effect and porous structure, which enhance the oxygen reduction or evolution reaction activities.

KW - Electrocatalysts

KW - Fe/Fe redox effect

KW - Iron phosphates

KW - Li–O battery

KW - Thermal reaction

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