Experimental Identification of a Lumped-Parameter Thermal Model of a Li-ion Pouch Cell Assembly

Thermal models of lithium-ion cells play a critical role in monitoring temperature distribution within battery packs, sizing cooling systems, and predicting potential thermal runaway scenarios. Pouch-type lithium-ion cells offer high energy and power density solutions, however, they are less thermally and mechanically stable than their cylindrical counter-parts. Pouch cells require appropriate containment structures to prevent excessive cell breathing that could alter electrical performance. Experiments done without such holding devices could conceal nominal cell behavior and lack repeatability. The holding structure, on the other hand, influences the heat dissipation of the cell and masks its temperature dynamics, making the characterization of its thermal properties challenging. This paper proposes a lumped-parameter thermal model and an experimental identification protocol aimed at extracting the parameters of interest, such as the cell thermal capacity, using temperature measurements collected both on the cell and fixture device components. The model is trained and validated under current profiles that are highly effective in exciting the system thermal dynamics.