Transient Phase Change in Two Phase Reaction between LiFePO4 and FePO4 under Battery Operation

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• 作者：Yuki Orikasa ; Takehiro Maeda ; Yukinori Koyama ; Haruno Murayama ; Katsutoshi Fukuda ; Hajime Tanida ; Hajime Arai ; Eiichiro Matsubara ; Yoshiharu Uchimoto ; Zempachi Ogumi
• 刊名：Chemistry of Materials
• 出版年：2013
• 出版时间：April 9, 2013
• 年：2013
• 卷：25
• 期：7
• 页码：1032-1039
• 全文大小：556K
• 年卷期：v.25,no.7(April 9, 2013)
• ISSN：1520-5002

文摘

Transient states of phase transition in LiFePO₄/FePO₄ for lithium ion battery positive electrodes are investigated by time-resolved measurements. To directly detect changes in electronic and crystal structures under battery operation, in situ time-resolved X-ray absorption and diffraction measurements are performed, respectively. The phase fraction change estimated by the iron valence change is similar to the electrochemically expected change. The transient change of lattice constant during two phase reaction is clearly observed by the time-resolved X-ray diffraction measurement. The nonequilibrium lithium extraction behavior deviates from the thermodynamic diagram of the two phase system, resulting in continuous phase transition during electrochemical reactions.

Keywords:

lithium ion battery; phase transition; nonequilibrium state; time-resolved measurement