Evolution of the morphology, structural and thermal stability of LiCoO2 during overcharge
Evolution of the morphology, structural and thermal stability of LiCoO2 during overcharge
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DOI：
10.1016/j.jechem.2020.06.071
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发表时间：
2021-04-01
影响因子：
13.1
通讯作者：
Li, Xinhai
中科院分区：
文献类型：
--
作者：
E, Zhitao;Guo, Huajun;Li, Xinhai
通过对LiCoO2在120%、150%、174%、190%和220%不同荷电状态(SOC)下的形貌、结构和热稳定性的分析，系统地研究了1000mAhLiCoO2/石墨电池的过充电行为。X射线衍射仪和扫描电子显微镜分析表明，LiCoO2经历了从O_3到H_1-3再到O_1的相变，同时伴随着颗粒的破碎和边界滑移，导致了174%的SOC后Co的显著溶解。对荷包电池和硬币电池的阻抗分析表明，阻抗增加的主要贡献来自于LiCoO2电极。差示扫描量热仪(DSC)结果表明，在结构崩塌、Co溶解和电解液氧化的共同作用下，LiCoO2正极材料的热稳定性随着过充电的进行而降低。我们希望这一全面的认识能够为提高LiCoO2/石墨袋电池的过充电性能提供有意义的指导。(C)2020中科院科学出版社和大连化学物理研究所。由Elsevier B.V.和科学出版社出版。版权所有。
The overcharge behaviors of 1000 mAh LiCoO2/graphite pouch cells are systematically investigated through the analysis of morphology, structural and thermal stability of LiCoO2 under different state of charge (SOC) of 120%, 150%, 174%, 190% and 220%. The LiCoO2 experiences the phase transition from O3 to H1-3 and then O1 together with the grain breakage and boundary slip as evidenced by XRD and SEM analysis respectively, which results in the pronounced Co dissolution after the SOC of 174%. The impedance analysis of the pouch cells and coin cells demonstrates that the main contribution of impedance increase originates from the LiCoO2 electrode. Under the combined effect of structural collapse, Co dissolution, and electrolyte oxidization, the thermal stability of LiCoO2 cathode materials reduces with the progressing of overcharge as revealed by differential scanning calorimetry (DSC) results. We hope that this comprehensive understanding can provide meaningful guidance for advancing the overcharge performance of LiCoO2/graphite pouch cells. (C) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.