Multi-directional laser scanning as innovative method to detect local cell damage during fast charging of lithium-ion cells

- Innovative method to measure the local thickness change of pouch cells.
- Local excess thickness change during fast charging is observed.
- Excess thickness change results in increased capacity fade.

Measuring the thickness change of lithium-ion cells is a reliable method to detect the intercalation stages of the electrodes, thickness increase during cycling and lithium plating. In this study, we introduce an innovative method to measure the thickness change of a pouch cell at multiple positions during operation. Using this technique, we disclose a local overshoot in the thickness change during fast charging near the current collector tabs at 25 °C, which significantly increases at 17 °C and is not detectable at 40 °C. As the cells show a better cycling stability at higher temperatures, the observed overshoot in thickness increase can be attributed to a failure mechanism. Opening the cells after cycling revealed that the anode was covered by a thick surface layer, so the failure mechanism is estimated to be lithium plating.