A hybrid phase-transition model of olivine LiFePO₄ for the charge and discharge processes

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• 作者：De Li^a ; Tao Zhang^a ; Xizheng Liu^a ; Ping He^b ; Ruwen Peng^b ; Mu Wang^b ; Min Han^b ; Haoshen Zhou^a ; ^b ; ^{hs.zhou@aist.go.jp}
• 关键词：Lithium-ion battery ; LiFePO4 ; Electrochemical impedance spectroscopy (EIS) ; Domino-cascade model ; Core&ndash ; shell model
• 刊名：Journal of Power Sources
• 出版年：2013
• 出版时间：1 July, 2013
• 年：2013
• 卷：233
• 期：Complete
• 页码：299-303
• 全文大小：1403 K

文摘

Generally, it is well known that the lithium-ion diffusion in olivine Li_xFePO₄ is correlated with the phase transition dominated by a domino-cascade model instead of a core-shell model. Based on the experiment result, we firstly found that the linear Warburg region of electrochemical impedance spectra should tilt with a small angle of 30¡ã for the domino-cascade model, while the core-shell model should correspond to a traditional angle of about 45¡ã. Considering that the measured Warburg impedance varies?along the charge and discharge processes, we firstly proposed a hybrid phase-transition model as?a combination of the domino-cascade model and the core-shell model to describe the olivine Li_xFePO₄.?And this hybrid model was possibly attributed to both the strong anisotropy in the bulk of olivine Li_xFePO₄ and the different properties between the lithiated and delithiated phases. Potentially, this micro-mechanism could be extended to some other two-phase electrode active materials in lithium ion batteries.