Spatially resolving lithium-ion battery aging by open-hardware scanning acoustic imaging
David Wasylowski, Niklas Kisseler, Heinrich Ditler, Morian Sonnet, Georg Fuchs, Florian Ringbeck, Dirk Uwe Sauer
Abstract
The internal mechanical condition of a lithium-ion battery is often disregarded but delivers essential information about the battery performance and lifetime. This work presents a method to measure the internal mechanical condition of lithium-ion cells with high spatial resolution through scanning acoustic imaging. An open-hardware ultrasound scan set-up has been engineered to increase the availability of acoustic imaging significantly. Using this set-up, three cells that were aged and clamped at different pressures have been imaged. The resulting ultrasound image clearly showed which parts of the cells have more severely aged than others. The cells which were clamped with the highest examined pressure (5 and 10 bar) showed the strongest covering layer and gas formation in the ultrasound scan. The mechanical effect of the aging seen in the ultrasound image was verified for each cell by conventional electrical and post-mortem analysis. At locations where the ultrasound image showed distinct irregularities, scanning electron microscopy images identified mossy surface layers typical for lithium plating.