A method for the fast estimation of a battery entropy-variation high-resolution curve – Application on a commercial LiFePO4/graphite cell

Abstract

The entropy-variation of a battery is responsible for heat generation or consumption during operation and its prior measurement is mandatory for developing a thermal model. It is generally done through the potentiometric method which is considered as a reference. However, it requires several days or weeks to get a look-up table with a 5 or 10 % SoC (State of Charge) resolution. In this study, a calorimetric method based on the inversion of a thermal model is proposed for the fast estimation of a nearly continuous curve of entropy-variation. This is achieved by separating the heats produced while charging and discharging the battery. The entropy-variation is then deduced from the extracted entropic heat. The proposed method is validated by comparing the results obtained with several current rates to measurements made with the potentiometric method.

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

“…There is a lack in the literature for using the calorimeter method directly to determine the entropic coefficient. The exception is Damay et al [29] who used the calorimeter as the direct measurement to determine the entropy profile with various current levels. In [29] the entropy effect is calculated from the subtraction of the charging heat and discharging heat, therefore only the average entropy profile of charge and discharge can be obtained.…”

“…The exception is Damay et al [29] who used the calorimeter as the direct measurement to determine the entropy profile with various current levels. In [29] the entropy effect is calculated from the subtraction of the charging heat and discharging heat, therefore only the average entropy profile of charge and discharge can be obtained. Overall the calorimetric method is a relatively fast method and it gives a continuously entropy profile for the whole SoC range.…”

Thermochemical Approach to Determining Battery’s Heat Release: RI2 Formula

“…The amount of heat depends on the discharging rate. Thus, in battery engineering practice, it is often suggested that the heat flow P follows the Joule-Lenz law that together with the Ohm law has the form P = I 2 R (I is the current and R is the battery's internal resistance), for instance, see works; [1][2][3][4] however, we have not found either theoretical or experimental proof of applicability of this formula. In case of the lithium-ion battery, the heat flow at high discharge current can overheat the battery up to unsafe conditions, and there is no need to repeat how widely lithiumion batteries are distributed in modern consumer and special devices.…”

Inverse Heat Transfer Analysis Method to Determine the Entropic Coefficient of Reversible Heat in Lithium-Ion Battery

“…Damay et al proposed the advanced calorimetric method along with the improvement plans of the existing calorimetric method. According to the authors, it is possible to accurately obtain entropyvariation as a function of SOC by creating experimental conditions of high cell temperatures and low current-rates [18]. Geifes et al extracted the entropic heat coefficient from the pulse relaxation measurement and refined them through least squares estimation.…”