Extensive fragmentation of copper current collectors was observed after spherical indentation on prismatic and large-format pouch Li-ion cells by 3D X-ray computed tomography (XCT). Microscopic analysis including scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and x-ray photoelectron microscopy (XPS) was carried out on copper current collectors from used commercial cells and pristine anodes. The copper-graphite cross-section images showed rough interface areas affected by reactions and diffusion in the used cell. Electron probe micro-analyzer (EPMA) element mapping showed the interface area was rich in oxygen and phosphorus. A detectable amount of phosphorus was also uniformly distributed inside the current collector. The same oxygen and phosphorus distributions were confirmed by STEM/EDS analysis. XPS depth profiles on multiple elements revealed the interface area of the aged anode was rich in Li, F, P, O and C and diffused at least 50 nm into the copper. In comparison, the pristine anode showed a very smooth C/Cu interface. No other elements were detected. For commercial cells, the reactions in the interface area and diffusion of multiple elements into the lattice and grain boundaries were responsible for the embrittlement of the copper current collectors. Permanent cell capacity loss was observed in electrochemical performance of the indented cells.

在球形和大型袋式锂离子电池上通过3D X射线计算机断层扫描（XCT）进行球形压痕后，观察到铜集电器的广泛破碎。显微镜的分析包括扫描电子显微镜（SEM），扫描透射电子显微镜（STEM）和X射线光电子显微镜（XPS），这些样品来自使用过的商用电池和原始阳极的铜集电器。铜-石墨横截面图像显示了受使用电池中反应和扩散影响的粗糙界面区域。电子探针微分析仪（EPMA）元素图谱显示界面区域富含氧和磷。可检测量的磷也均匀地分布在集电器内部。通过STEM / EDS分析确认了相同的氧和磷分布。XPS在多个元素上的深度剖面显示，老化阳极的界面区域富含Li，F，P，O和C，并扩散到铜中至少50 nm。相比之下，原始阳极显示出非常光滑的C / Cu界面。未检测到其他元素。对于商用电池，界面区域中的反应以及多种元素向晶格和晶界的扩散是造成铜集电器脆化的原因。在缩进电池的电化学性能中观察到永久的电池容量损失。界面区域的反应以及多种元素向晶格和晶界的扩散是造成铜集电器脆化的原因。在缩进电池的电化学性能中观察到永久的电池容量损失。界面区域的反应以及多种元素向晶格和晶界的扩散是造成铜集电器脆化的原因。在缩进电池的电化学性能中观察到永久的电池容量损失。