Insight into the inhomogeneous capacity distribution characteristic of LiFePO4 cathode in large-format lithium ion cell
Insight into the inhomogeneous capacity distribution characteristic of LiFePO4 cathode in large-format lithium ion cell
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DOI：
10.1016/j.ceramint.2020.12.037
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发表时间：
2020-12
影响因子：
5.2
通讯作者：
Shu-xin Zhuang;Deli Jia;Quanbin Wang;Yongfeng Hu;Minshu Zhang;Xiaodan Li;Jianping Lin;Qihui Wu;Jigang Zhou;Mi Lu
中科院分区：
文献类型：
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作者：
Shu-xin Zhuang;Deli Jia;Quanbin Wang;Yongfeng Hu;Minshu Zhang;Xiaodan Li;Jianping Lin;Qihui Wu;Jigang Zhou;Mi Lu
采用半电池充放电测试、高分辨透射电镜、X射线光电子能谱和X射线吸收光谱分析等方法，对大规格LiFePO4基锂离子电池在2500次充放电循环后阴极的不均匀容量衰减分布进行了分析。结果表明，电极的初始比容量具有明显的位置依赖性，表明电极上发生了非均相反应。在极耳位置附近的低初始充电容量可以在放电后恢复，表明容量退化是由于活性锂的损失，而不是晶体结构的破坏。X射线光电子能谱和高分辨透射电子显微镜的结果进一步验证了这些推论，X射线吸收谱分析结果表明，LiFePO4的结构变化差异主要在表面，而不是体相。
The inhomogeneous capacity degradation distribution of large-format LiFePO4-based lithium ion cell after 2500 charge-discharge cycles is analyzed via the selected regions of the cathodes using half-cell charge-discharge test, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy analysis. The results showed that the initial specific charge capacities demonstrate an obvious position-dependent characteristic, indicating inhomogeneous reactions occurring on the electrode. The low initial charge capacities near the tab location can be recovered after discharging, indicating the capacity degradation is from the active lithium loss, rather than the crystal structure destruction. The X-ray photoelectron spectroscopy and high resolution transmission electron microscopy results further verified these deduction and the X-ray absorption spectroscopy analysis results indicate that the difference on the structure change of LiFePO4is mainly at the surface, rather than in the bulk.