A Time- and Cost-Effective Method for Entropic Coefficient Determination of a Large Commercial Battery Cell

The entropic coefficient of a lithium-ion battery cell is used to calculate the reversible heat of a battery during operation, which is a nonnegligible part of the battery thermal modeling. The contribution of this article is to propose a novel method to establish the entropic coefficient profile of a 26-Ah commercial pouch cell and compare the results with those obtained from the traditional potentiometric and calorimetric methods, and all are found to be in a good agreement. The originality of this article is to use a method, which consists of supplying a square pulse current waveform at a certain frequency, and thus, the resulting heat variation could be successfully linked to the input current using Fourier analysis. The current magnitudes used were 1 and 1.5 C, which are representative of the normal operation current in an electrified vehicle application. The method proposed is found to be cost efficient with a short experiment time and simple experiment setup. In fact, it can be used to characterize cells that are already mounted in a pack without access to a climate chamber or calorimeter.