Cell-to-cell inconsistency analysis and structure optimization for a liquid-cooled cylindrical battery module

Abstract

It is critical to understand the cell-to-cell inconsistency among cells to obtain a better performance of the battery module. However, the battery inconsistency is always not considered in the traditional designs of the battery module, especially for liquid-cooled modules. In this study, a liquid-cooled 8S2P cylindrical module with thermal-conductive blocks and a single flat tube was designed. A multiphysics model was established to capture the electrical, thermal and aging behavior of the module numerically. First, the cell-to-cell inconsistency among cells was simulated with the verified multiphysics model for different module layouts. The results showed that the module with S configuration offered superior thermal and aging performance to the module with I configuration. The maximum temperature difference among cells was decreased by 0.4 K for the module with S configuration. The module SOH and SOH consistency improved by 0.8 % and 210 % after 400 cycles for the S configuration, respectively. Then, the effects of the height (h) and height increment (Δh) of thermal-conductive blocks on the electrical and thermal performance of the module were discussed. The maximum temperature of the module and maximum temperature difference among cells were decreased by 0.6 K and 0.1 K with increasing h, respectively. However, the maximum temperature of the module and maximum temperature difference among cells were decreased by 0.001 K and 0.6 K with increasing Δh, respectively. The mean value of maximum current variation over time and maximum SOC difference among cells at the end of discharge were slightly increased by 0.01A and 0.02 % with increasing Δh, respectively but almost insensitive to the variation of h.