Lithium-Ion Batteries’ State-Of-Charge and Health Assessment by Non-Contact Ultrasound Spectroscopy

Use of non-contact ultrasonic spectroscopy for the characterization and test of Lithium-ion battery pouch cells is investigated. Thickness resonances were excited and detected throughout the discharge cycles. The results reveal that it is possible to generate and measure thickness resonances in the batteries and that these resonances are consistently sensitive to the State-of-Charge of the cell as well as to temperature-induced reversible alterations. Thickness and velocity were obtained simultaneously from the measured transmission coefficients. Results reveals that this technique is capable of detecting mechanical changes in the batteries due to electromechanical operation. Since this technique is completely contactless and non-invasive, it can be applied both as quality test in production or in operando, presenting great potential as an in-line inspection tool for battery manufacturing applications.