Criteria for quality control: The influence of electrode defects on the performance of lithium-ion batteries is reviewed. Point and line defects as well as inhomogeneities in microstructure and composition and metallic impurities are addressed. There is urgent need to investigate and understand more deeply fundamental mechanisms but also quantitative relationships between the nature and extent of defects and the electrochemical performance of electrodes to develop effective quality assurance measures and improve process management.
The continuing rise of electric mobility is driving demand for lithium-ion batteries to unprecedented levels. To ensure efficient production of high quality, yet affordable battery cells, while making the best use of available raw materials and processes, reasonable quality assurance criteria are needed. A step of particular importance, affecting all downstream processes, lies in electrode manufacturing including mixing, coating, drying, and calendering. Several classes of defects which originate in these processes are well-known and detectable using various methods. The crucial point, however, lies in the quantification of their electrochemical significance, i. e., in an evaluation, which defect types, sizes and concentrations can be tolerated without impacting cell performance. Herein, we review the still scarce literature on that topic. It is found that, although the impact of some defects is quite well understood, others almost completely lack an evaluation of their criticality. We finally make suggestions for further studies paving the way to deduce knowledge-based quality assurance criteria for the large variety of coating defects occurring in lithium-ion battery electrodes.Zum Volltext