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Stabilizing the Structure of LiCoPO4 Nanocrystals via Addition of Fe3+: Formation of Fe3+ Surface Layer, Creation of Diffusion-Enhancing Vacancies, and Enabling High-Voltage Battery Operation

Okita, Naohisa and Kisu, Kazuaki and Iwama, Etsuro and Sakai, Yuki and Lim, Yiyo and Takami, Yusuke and Sougrati, Moulay Tahar and Brousse, Thierry and Rozier, Patrick and Simon, Patrice and Naoi, Wako and Naoi, Katsuhiko Stabilizing the Structure of LiCoPO4 Nanocrystals via Addition of Fe3+: Formation of Fe3+ Surface Layer, Creation of Diffusion-Enhancing Vacancies, and Enabling High-Voltage Battery Operation. (2018) Chemistry of Materials, 30 (19). 6675-6683. ISSN 0897-4756

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Official URL: https://doi.org/10.1021/acs.chemmater.8b01965

Abstract

Factors affecting the cyclability of the Fe-substituted LiCoPO4 (LiCo0.8Fe0.2PO4, LCFP) material were elucidated, including both the structural and electrode/electrolyte stability. Electrochemical characterization of the synthesized LCFP nanoparticles lends clear evidence for improved electrochemical stability of LCP, as well as enhanced rate capability, with Fe3+ substitution. Surface analysis using X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) suggest that Fe enrichment on the surface of LCFP occurs through the oxidation of Fe2+ into Fe3+ in the synthesis process. The Fe3+-rich phase on the LCP surface enhances the stability of the delithiated phase, preventing oxidative reactions with electrolytes during high-voltage operation. This surface protection persists as long as the electrochemical reduction of Fe3+ is avoided by ensuring that the full range of operating voltages lie above the Fe3+/Fe2+ redox potential. Our findings may offer new approaches to stabilize the structure of LCP and other high-voltage positive electrodes for use in 5 V-class Li-ion batteries.

Item Type:Article
HAL Id:hal-01907737
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Other partners > Collège de France (FRANCE)
Other partners > Ecole Nationale Supérieure de Chimie de Paris - ENSCP (FRANCE)
Other partners > Ecole Nationale Supérieure de Chimie de Montpellier - ENSCM (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Other partners > Institut polytechnique de Grenoble (FRANCE)
Other partners > National Tsing Hua University - NTHU (TAIWAN)
Other partners > Sorbonne Université (FRANCE)
Other partners > Tokyo University of Agriculture and Technology - TUAT (JAPAN)
Other partners > Tokyo University of the Arts - TUA (JAPAN)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
Other partners > Université de Nantes (FRANCE)
Other partners > Université de Picardie Jules Verne (FRANCE)
Other partners > Université de Montpellier 1 (FRANCE)
Other partners > Université de Montpellier 2 (FRANCE)
Other partners > Université de Pau et des Pays de l'Adour - UPPA (FRANCE)
Other partners > Université de Montpellier (FRANCE)
Laboratory name:
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Deposited By: cirimat webmestre
Deposited On:25 Feb 2019 13:55

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