Floating aging mechanism of lithium-ion capacitors: Impedance model and post-mortem analysis

• DOI: 10.1016/j.jpowsour.2022.232597
• Publication Date: 2022-12-30T10:42:04Z
• Authors: Shuang Song; Xiong Zhang; Yabin An; Tao Hu; Congkai Sun; Lei Wang; Chen Li; Xiaohu Zhang; Kai Wang; Zhichuan J. Xu; Xianzhong Sun; Yanwei Ma
• Keywords: Accelerated aging; Degradation

For a new type of energy storage device of lithium-ion capacitor (LIC), it is necessary to evaluate its lifetime for successful market expansion. This paper focuses on explaining the floating aging mechanism under different voltages, combining non-destructive and destructive perspectives. We have accelerated several cells in high temperature climate chambers for overall aging time of more than one year. The floating voltages are set as 2.2, 3 and 3.8 V. The aging mechanism analysis is preliminarily explored using impedance model with both physical meaning and high fitting degree. We perform post-mortem analysis on a brand-new cell and aged ones with different floating voltages to verify the aging mechanism predicted by the impedance model method. We have found that the degradation behavior of high floating voltage is different from that of low floating voltage. The medium voltage region performs well in calendar aging, which is beneficial to the reliability of LIC storage. Some recommendations are given for the non-destructive method, which is helpful for future lifespan research using impedance model. This work was financially supported by the National Key R&D Program of China [grant number 2021YFB2402002]; Strategic Priority Research Program of Chinese Academy of Sciences [grant number XDA21050302]; National Natural Science Foundation of China [grant number 51822706, 52077207 and 51777200]; Beijing Natural Science Foundation [grant number JQ19012] and Special Research Assistant Program, Chinese Academy of Sciences.