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Title
Japanese: 
English:Irreversible Phase Transition between LiFePO4 and FePO4 during High-rate Charge-discharge Reaction by operando X-ray Diffraction 
Author
Japanese: Ikuma Takahashi, Takuya Mori, Takahiro Yoshinari, Yuki Orikasa, Yukinori Koyama, Haruno Murayama, Katsutoshi Fukuda, 秦野 正治, 荒井 創, 内本 喜晴, 寺井 隆幸.  
English: Ikuma Takahashi, Takuya Mori, Takahiro Yoshinari, Yuki Orikasa, Yukinori Koyama, Haruno Murayama, Katsutoshi Fukuda, Masaharu Hatano, Hajime Arai, Yoshiharu Uchimoto, Takayuki Terai.  
Language English 
Journal/Book name
Japanese:Journal of Power Sources 
English:Journal of Power Sources 
Volume, Number, Page Vol. 309        pp. 122
Published date Jan. 21, 2017 
Publisher
Japanese: 
English: 
Conference name
Japanese: 
English: 
Conference site
Japanese: 
English: 
Abstract LiFePO4 is a practically used cathode material for lithium-ion batteries due to a high theoretical capacity, high cycle capability and the high-rate performance. The metastable LixFePO4 (LxFP) phase with an in- termediate composition appears in the non-equilibrium state at high-rate condition. However, the for- mation process of the metastable LxFP phase and its impact to the electrochemical property are still unclear. In order to elucidate these points, we directly observed the phase transition behavior by applying operando XRD during 10C charge-discharge. LxFP phase does not form in charge reaction but preferentially forms in discharge reaction. The phase transition from LxFP to Li-rich phase is less likely to proceed in the end of discharge reaction. The asymmetric phase transition between LiFePO4 and FePO4 results in decreasing the discharge capacity and increasing the irreversible capacity at high-rate conditions.

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