18650-type cells with 2.5 Ah capacity are cycled at both 25 °C and 0 °C separately, and at 25 °C two charging protocols (constant current, and constant current-constant voltage charge) are used. Differential voltage analysis (dV/dQ) and alternating current (AC) impedance are mainly used to investigate battery degradation mechanisms quantitatively. The dV/dQ suggests that active cathode loss and loss of lithium inventory (LLI) are the dominating degradation factors. Significant microcracks are observed in the fatigued cathode particles from the scanning electron microscopy (SEM) images. Crystal structure parameters of selected fatigued batteries at fully charged state are determined by in situ high-resolution neutron powder diffraction. Obvious increases of ohmic resistance and solid electrolyte interphase (SEI) resistance occur when the battery capacity fade falls beneath 20%. Continuous charge transfer resistance and Warburg impedance coefficient (W_.eff) increase are observed in the course of cycling. Correlation analysis is performed to bridge the gap between material loss as well as LLI and impedance increase. The increase of the charge transfer resistance is related to both active cathode loss and LLI, and a functional relationship is revealed between LLI and W_.eff regardless of the used cycling protocols.

容量为2.5 Ah的18650型电池在25°C和0°C时分别循环，在25°C时使用两种充电方案（恒定电流和恒定电流-恒定电压充电）。差分电压分析（dV / dQ）和交流（AC）阻抗主要用于定量研究电池退化机理。所述的dV / dQ的表明活性阴极损耗和锂库存（LLI）的损失是主导因素降解。从扫描电子显微镜（SEM）图像中可以观察到疲劳的阴极颗粒中出现了明显的微裂纹。所选疲劳电池在充满电状态下的晶体结构参数由原位确定高分辨率中子粉末衍射。当电池容量下降到20％以下时，欧姆电阻和固体电解质中间相（SEI）电阻会明显增加。在循环过程中观察到连续的电荷转移电阻和Warburg阻抗系数（W _.eff）增加。进行相关分析以弥合材料损耗以及LLI和阻抗增加之间的差距。的电荷转移电阻的增加与两个阴极活性损失和LLI，和功能关系显露LLI之间W¯¯ _.eff不管所使用的循环协议。