Dynamic measurement of the entropy coefficient for battery cells

The entropy coefficient is an important quantity to describe thermodynamic processes of battery cells and to model the temperature dependency of the open-circuit voltage. Determining the entropy via potentiometric measurements is often time-consuming. Therefore, several methods were developed to quickly estimate the entropy coefficient. This paper presents a new method, which is relatively simple in its execution and evaluation. The method is based on relating a dynamic temperature change to the cell's voltage change at an induced exponential temperature progression. Due to the dynamic of this process, the measurement time will be reduced compared to the potentiometric method by factor 13 for the executed experiments under its stated conditions.

Automated summary

The entropy coefficient plays a crucial role in describing the thermodynamic behavior of battery cells and modeling the temperature effects on open-circuit voltage. Estimating the entropy through potentiometric measurements is time-consuming. To address this, various methods have been developed to quickly estimate the entropy coefficient. This paper proposes a new method that is comparatively simple in its execution and evaluation. The method utilizes the relationship between dynamic temperature changes and voltage variations in order to estimate the entropy coefficient, significantly reducing the measurement time by a factor of 13 compared to the potentiometric method under the specified conditions.