A Sensor Model to Simulate the Excitation and Propagation of Lamb Waves in Lithium-Ion Pouch Cells

The demand for lithium-ion battery cell monitoring is growing rapidly as the number of cells used in various applications increases. A novel monitoring approach is based on the mechanical properties of the battery, which change during the charge/discharge process and during its lifetime. In this approach, an acoustic wave is generated inside the battery by a transmitter and propagates through the layered structure of the cell to a receiver. The propagation speed of the wave changes depending on the mechanical properties of the cell, and so does the measurable time of flight between the transmitter and receiver. To apply this monitoring approach, it is essential to understand how this wave actually forms and travels through the individual layers. To improve this understanding, a model is presented that simulates both the generation and propagation of the wave within the battery. The model is parametrized by performing reference measurements and a tear down analysis of the battery. The simulation result shows good agreement with the measurement results and also provides a visualization of the acoustic wave motion within the cell, which greatly improves the understanding of the propagating wave.