Increased Conductivity in the Metastable Intermediate in LixFePO4 Electrode

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• 作者：Jiechen Lu ; Gosuke Oyama ; Shin-ichi Nishimura ; Atsuo Yamada
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：February 23, 2016
• 年：2016
• 卷：28
• 期：4
• 页码：1101-1106
• 全文大小：382K
• ISSN：1520-5002

文摘

With increasing concerns about energy and environmental issues, lithium ion batteries are now penetrating into large-scale applications such as electric vehicles. As an electrode reaction process, it is generally believed that two-phase reaction with structural rearrangement and large lattice mismatch impedes high-rate capability. However, Li_xFePO₄, with its two-phase reaction between LiFePO₄ and FePO₄, exhibits an exceptional high-rate performance. In this article, after confirming the existence of a single-phase reaction even under moderate rates, we demonstrate an approximately 2 orders of magnitude increase of the conductivity for the quenched intermediate Li_0.6FePO₄. In addition to the widely accepted strain relaxation effect at the two-phase interface, the dramatically increased conductivity due to polaron/lithium carrier density increase in the intermediate phase should be highlighted as an important factor to accelerate the electrode reaction of olivine Li_xFePO₄.