The role of structural defects in commercial lithium-ion batteries

The manufacturing of commercial lithium-ion batteries (LIBs) involves a number of sophisticated production processes. Various cell defects can be induced, and, depending on their structural and chemical characteristics, they could lead to acute failure and/or chronic degradation. Although tremendous efforts have been devoted to develop a robust quality control (QC) procedure, the functional role of the cell defects is not well understood. Here, we address this question through a systematic experimental study of commercial 18650-type LIBs that have failed the QC inspection due to a self-discharging effect. We identify and recover the defective regions from the cell and conduct a comprehensive investigation from the chemical, structural, and morphological perspectives. Our results reveal how the structural defects affect the cell performance, which is highly important to industry-scale battery production.