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Okita, N., Kisu, K., Iwama, E., Sakai, Y., Lim, Y., Takami, Y., Sougrati, M. T., Brousse, T., Rozier, P., Simon, P., Naoi, W. & Naoi, K. (2018) 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. Chemistry of Materials, 30 6675–6683.
Added by: Richard Baschera (2018-12-19 10:37:24) Last edited by: Richard Baschera (2018-12-19 10:41:03) |
| Type de référence: Article DOI: 10.1021/acs.chemmater.8b01965 Clé BibTeX: Okita2018 Voir tous les détails bibliographiques  |
Catégories: INTERNATIONAL, ST2E Créateurs: Brousse, Iwama, Kisu, Lim, Naoi, Naoi, Okita, Rozier, Sakai, Simon, Sougrati, Takami Collection: Chemistry of Materials |
Consultations : 1/370
Indice de consultation : 4% Indice de popularité : 1% |
| Résumé |
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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.
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