Comprehensive understanding of the effects of imbalanced cell via battery module tests for further usage of cycled batteries

In this study, a comprehensive understanding on the battery module with an imbalanced cell is assessed in terms of its electrical, thermal, and electrochemical effects. By conducting electrical and thermal analysis using a 2 × 2 battery module for electric vehicle battery pack representative unit, normally combined with series and parallel, we observe property variations at the charge and discharge voltage profiles, as well as impacts of distinct reactions by series and parallel connections. The series-connected cell configuration on the module corresponds to the voltage variance, while the parallel-connected one induces temperature disparity. This comprehensive examination through two modules (model vs. reference module) is conducted to ascertain whether the outcomes of the electrical and thermal property analyses correspond to the internal chemical condition and configuration of the battery when the imbalanced modules connect in series and parallel are in operation. Our findings reveal a significant relationship between the electrical imbalances in each cell, the thermal consequences on the battery module, and the electrochemical impacts on the electrodes. However, we also reveal that there are normal cells among battery module when degraded with imbalances. Based on those results, our research provides economical information for the process of repurposing battery electrodes from imbalanced battery modules that will be appeared after cycled (or degraded) electric vehicle battery, which is crucial for improving the efficiency of an imbalanced batteries.