Automated inline visual inspection and 3D measuring in electrode manufacturing

Abstract

Electrode manufacturing is one of the most critical processes within the energy storage production chain, as the electrodes coating and drying quality determines the later performance of the energy storage system in large part. Critical quality losses within the electrode coating are often optical visible, but cannot be automatically and inline inspected. Often small defects like agglomerates, capillary cracks or pinholes in the carbon or metal oxide based layers have to be detected at high web speeds. In the work described in this paper it was examined which kind of features and defects can be recognized by two optical methods: visual inspection and 3D measuring.A visual camera in conjunction with a white illumination and a 3D data laser line system has been used. Image processing algorithms are applied on the scanned data to detect pinholes and agglomerates. Also thickness of coating, gradient of the coating edge and form anomalies can be determined out of the produced data. Reliable evaluation of pinholes even of small sizes has been proofed. Particle agglomerations are more challenging. To achieve good enough data for 3D evaluation standard sensors are often insufficient, due to the necessary resolution and the production speed that requires high scanning frequency.In order to provide an automated, digitalized production and inspection system, the devices were coupled to a central experiment management system. Their operation is controlled non-locally in the cloud and synchronized with the execution of experiments. The acquired raw data is stored for later evaluation and long-term archiving.

From Materials to Cell: State-of-the-Art and Prospective Technologies for Lithium-Ion Battery Electrode Processing

“…To evaluate electrode rolls in-line, beta transmission lines have been used to measure the thickness; however, this could cause safety concerns and is expensive. Laser triangulation has been successfully implemented as a far less expensive, nondestructive replacement. − Laser triangulation can scan a large area of coating based on the placement of sensors. Similarly, laser calipers consist of sensors located directly above and below a fixed point on the coating line.…”

Measuring Instruments for Characterization of Intermediate Products in Electrode Manufacturing of Lithium‐Ion Batteries

“…Possible inline measuring systems for the wet film thickness include laser triangulation, [52,53] confocal chromatic sensor, [54] or white light interferometer. [18,[55][56][57] It should be noted that the measurement range and accuracy reported for these systems are affected by their distance from the object and should be interpreted as approximate reference values.…”

Applications and Development of X-ray Inspection Techniques in Battery Cell Production

“…Multiple temperature profiles are typically used to influence the porosity of the electrode, the adhesion and the distribution of carbon black as well as binder. For the inline inspection of quality parameters, e.g., ultrasound is used to determine the mass loading [24] or camera-based optical methods are used to determine coating defects on the surface [25][26][27]. Applications of X-ray based investigations in the coating process are mainly limited to the offline analysis of material properties.…”