Determination of the Entropic Heat Coefficient of Lithium‐Ion Batteries Based on a Continuous Measurement Method

A comprehensive understanding of thermal battery behavior and, consequently, the design of efficient thermal management systems are crucial for optimal performance, a high safety level, and the prolonged lifetime of batteries in automotive applications. In this context, knowledge of the heat release within the battery is a key parameter. In this work, a methodology is investigated for determining the reversible heat release based on continuous quasi‐open‐circuit‐voltage (qOCV) measurements, which is not yet fully established in the literature. Three key factors influencing the evaluation of the entropic heat coefficient are presented and it is discussed in detail how these should be taken into account for the first time. The entropic coefficients derived from the continuous approach are compared with values obtained from potentiometric measurements of the same pouch cell and show a high level of accuracy for the continuous qOCV method. The standard battery cycler is used, with a measuring uncertainty of 1 mV, yields results that are in very good agreement with the broad spectrum of literature values, obtained using different methodologies and uncertainties. The validity and robustness of the approach are further demonstrated by applying the continuous method to data from a different automotive prismatic cell with a significantly different testing procedure.