Investigation of the influence of different aging stresses on the heat generation of an NMC Li-Ion battery

Thermal models get more and more important for the performance of battery systems within vehicle applications. Knowing how temperature and heat of the cells and assembled systems are evolving, can decrease the potential limitations. It leads to a more constant performance. The thermal behavior is not only dependent to actual conditions like SoC, ambient temperature and requested power, but also to state of health. Through the many possible applications and stresses, batteries degrade in a variety of ways.

This study will investigate the effects of the different aging mechanisms, resulting by different load-scenarios, on heat generation of a battery cell. For this, NMC 2032 coin-cells will be recurrently measured with a multi module calorimeter. The calorimeter (NETZSCH”;” Germany) is equipped with a coin-cell module using the DSC-method (Differential Scanning Calorimetry). The methodology enables the possibility of the in-situ measurement of the heat generation. Between these ongoing check-up measurements, the cells will be cycled and aged under different stress focuses. The differential voltage analysis supplements the scope of check up routine.

Aim of this work is to find a correlation between the changes in the heat generation signal over aging and the underlying aging stresses. For this purpose, a comparison with the results from the differential stress analysis is also made. In the reverse can a correlation of heat generation and aging stresses help to qualify and cluster battery cells for second life applications.