Abstract Herein, performance degradation of pouch type of 20 A h lithium ion battery from electric bus is clarified after a classification using the resistance value from A to D grade. The obtained cells are carefully disassembled to produce cathode, anode, and separator. Scanning electron microscopy and energy dispersive spectroscopy analysis reveal that morphological change of electrode mostly occur in the anodes surface in D-grade cells, while cathodes of all the grades mostly remain similar. Although the change of crystalline structure of all electrodes is negligible, a growth of solid-electrolyte interphase film mostly happen in the D-grade anodes, which is confirmed by X-ray photoelectron spectroscopy analysis. Furthermore, the degradation of cycle and rate performance happen in the anode of D-grade cells, whereas the cathodes remain invariant irrespective of grade. Furthermore, the disassembled separators exhibit that the Gurley number of separators is commonly increased in the used cells.

中文翻译：

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20 ah LIB软包电池用于电动公交车后性能下降的澄清

摘要 本文通过A-D级电阻值分级，明确电动客车袋装式20 A h锂离子电池的性能退化。将获得的电池仔细拆解以生产阴极、阳极和隔板。扫描电镜和能量色散谱分析表明，电极的形态变化主要发生在 D 级电池的阳极表面，而所有级别的阴极大多保持相似。尽管所有电极的晶体结构变化都可以忽略不计，但固体电解质界面膜的生长主要发生在 D 级阳极，这通过 X 射线光电子能谱分析得到证实。此外，循环和倍率性能的下降发生在 D 级电池的阳极，而无论等级如何，阴极都保持不变。此外，拆开的隔板表明，在使用过的电池中，隔板的 Gurley 数通常会增加。