Guided waves propagation in lithium-ion batteries: Theoretical modeling and experimental analysis

Ultrasonic guided wave detection technology can feasibly measure and monitor the state of charge. The experimental studies in a customized cell were also performed to acquire the relationship between guided waves generated in a pitch-catch mode and battery states of charge (SOC). An analytical acoustic model was developed to model the guided wave propagation characteristics of lithium-ion battery with different SOC. The multi-layered and porous structure of lithium-ion battery was considered by combining the state-vector formalism and the Legendre polynomial method with the Biot theory. Concurrently, the chemo-mechanical coupling problem in the electrochemical reaction process was considered by using the Mechanics of Incremental Deformations theory. Based on this, the relationships between structural characteristics, dynamic coupling characteristics, state of charge and guided wave behavior in commercial lithium-ion batteries were numerically analyzed. The feasibility and accuracy of the numerical model were proved by the comparison of previous experimental time of flight results (Ladpli et al., 2018) [1] and its corresponding theoretical solutions. Furthermore, the extracted experimental time of flights was in good agreement with the theoretical results. The mapping relationship between the state of charge and the propagation characteristics lays a foundation for the nondestructive evaluation and quantitative estimation of the state characteristics of lithium-ion batteries.