https://doi.org/10.1140/epjs/s11734-025-01649-1
Regular Article
In-line monitoring of a multi-stage drying process for battery electrodes: vol. 2—advancing measurement techniques with chromatic confocal sensors
1
Thin Film Technology, Karlsruhe Institute of Technology, Kaiserstraße 12, 76131, Karlsruhe, Germany
2
Material Research Center for Energy Systems (MZE), Karlsruhe Institute of Technology, Kaiserstraße 12, 76131, Karlsruhe, Germany
Received:
7
January
2025
Accepted:
24
April
2025
Published online:
13
May
2025
The drying of electrode coatings represents a critical stage in the battery production process, where even slight deviations in drying conditions can lead to defects, resulting in high rejection rates, increased costs, and material waste. To address these challenges, the integration of in-line measurement technologies offers a promising solution. Following the investigation of scattered light sensors in vol. 1 of the study Mohacsi et al. (in Eur Phys J Special Topics, 1–9, 2024), the present work explores the potential of chromatic confocal sensors for monitoring the drying process of electrodes. A dual-sided measurement system employing two chromatic confocal point sensors was established, enabling precise layer thickness measurements even on a substrate belt significantly affected by vibrations. It was demonstrated that the standard deviation of the thickness signal serves as a reliable metric for characterizing surface roughness. Initial drying experiments compared the signal profiles of the chromatic confocal sensors with those of the previously studied scattered light sensor. This comparison provided strong evidence that chromatic confocal sensors can reliably detect key points during drying, such as the onset of pore-emptying. In further experiments, the layer thickness measurements from the confocal sensors were combined with gravimetric determinations of layer porosity, offering deeper insights into the mechanisms occurring during drying. Overall, the results suggest that chromatic confocal sensors could be a valuable tool not only for quality assurance during drying but also for optimizing the configuration of a three-stage drying process.
© The Author(s) 2025
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