A Coupled Thermo-Mechanical Dynamic Characterization of Cylindrical Batteries

Lithium-ion batteries have complicated dynamics and temperature behavior. In this paper, a dynamic system previously developed to characterize the voltage response was extended to estimate the heat generation rate due to the electrochemical reactions that a battery undergoes as being discharged. The dynamic system based on a modally decomposed three-degree-of-freedom, spring-mass-damper analogy was used to estimate the cells terminal voltage, open-circuit voltage and the mass transfer and boundary layer effects. The modal parameters were determined by minimizing the error between the experimental and simulated time responses. Then, these estimated parameters were coupled with a lumped thermal model to predict the temperature profiles of two cylindrical lithium-ion batteries. To capture the dynamic voltage and temperature responses, hybrid pulse power characterization (HPPC) tests were conducted with thermocouples. It was found that the dynamic model was able to accurately estimate the nonlinear dynamics of the batteries; therefore, the electrochemical heat generation rate was successfully able predict the surface temperature profile at 1C and 2C discharge rates.