Markus Koller, researcher in the field of Electric Vehicle Technologies at AIT, recently successfully completed his doctoral studies in electrical engineering at Graz University of Technology. We extend our heartfelt congratulations!
The topic of Koller's dissertation was " Measurement of Mechanical Properties of Lithium-Ion Secondary Batteries to Determine their 'State of X' (SoX)", here is the abstract:
Current Battery Management Systems (BMS) in larger Lithium-Ion secondary battery packs determine the State of X, meaning, among others, the State-of-Charge and the State-of-Health via a single parameter or via a combination of multiple parameters derived from the electrical two pole behavior, or the history of the battery. These parameters are typically the cells’ voltage, current, impedance, and capacity, and the number of charge and discharge cycles. Structural defects like swollen or deformed batteries are difficult to recognize with current BMS. Such unnoticed mechanical damage can result in serious fires and injuries. However, with the usual parameters it is difficult to draw conclusions about the mechanical state of the battery.
This work aims to improve the estimation of the State-of-Safety as well as the State-of-Function by determining the mechanical properties of Lithium-Ion batteries. For this, additional mechanical sensing is implemented, using small-sized and low-cost piezoelectric ultrasound transducers as emitters and sensors mounted on the surface of pouch cells. During cycling, the transmitted ultrasound signal changes its properties such as amplitude and Time of Flight, which correlate with the changing mechanical properties as well as the State-of-Charge.
We are very happy about this great success and wish Markus Koller all the best for his further scientific career!