Ultrasonic Battery Management System for Lamb wave mode tracking on Lithium-ion pouch cells

During charging and discharging, lithium-ion secondary batteries (LIBs) change their mechanical properties due to intercalation and deintercalation of lithium-ions in the electrodes. In this work, a novel ultrasonic battery management system (UBMS) with dedicated FPGA hard- and software has been developed that can track these mechanical changes by using ultrasonic sensors. In particular, the group velocity of the fundamental Lamb mode A0 is tracked and compared with the proposed simulation model. Previous studies have shown that the Young’s modulus of the anode coating changes significantly during cycling. By incorporating this information into the simulation, a change in this value will drastically affect the group velocity of the propagating wave mode A0, which can also be seen in the measurements carried out. To represent a realistic use case, the behaviour of the Lamb mode A0 is measured at different temperatures, which have a big influence on the group velocity of the propagating wave mode. The collected ultrasonic BMS data was further used to develop a state-of-charge (SOC) and temperature estimator. The accuracy of this novel method is discussed. With the addition of the ultrasonic sensors, the BMS can have a larger and better database that can be used to provide a more accurate estimate of the mechanical properties of LIBs and their SOC and temperature.