In-line quality control for electrode manufacturing: Advanced sensing and defect detection in battery production

As the demand for high-performance lithium-ion batteries increases, maintaining a consistent electrode quality is critical. This study demonstrates a comparative inline metrology framework for real-time defect detection strategy for NMC622 cathode manufacturing. Five representative defect types were deliberately introduced through controlled variations in the slurry mixing intensity, drying conditions, coating parameters, and external particle contamination to establish a structured basis for the inline detection evaluation and electrochemical characterization. Electrochemical tests are performed on defect-containing coin and pouch cells alongside reference cells to quantify the performance impact of each defect type and to assess their relative criticality. This framework generates a training image dataset for Laser Speckle Photometry (LSP), enabling detection and reducing the incidence of mentioned defect type. The system is integrated into a pilot-scale roll-to-roll (R2R) coating line, demonstrating defect detection and classification under production conditions and establishing a validation platform for future scale-up toward industrial production. Real-time measurements were carried out using both the LSP and a commercial line-scan camera system to compare the identifiable defects on the same manufactured electrode across two pilot-scale coating lines. The integration of both systems highlights the feasibility of multimodal inline defect monitoring in battery electrode manufacturing.