| Autor: |
Okita, Naohisa, Kisu, Kazuaki, Iwama, Etsuro, Sakai, Yuki, Lim, Yiyo, Takami, Yusuke, Sougrati, Moulay Tahar, Brousse, Thierry, Rozier, Patrick, Simon, Patrice, Naoi, Wako, Naoi, Katsuhiko |
| Zdroj: |
Chemistry of Materials; October 2018, Vol. 30 Issue: 19 p6675-6683, 9p |
| Abstrakt: |
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. |
| Databáze: |
Supplemental Index |
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