Thermal behaviors analysis of 55 Ah large-format lithium-ion pouch cells with different cell aspect ratios, tab locations, and C-rates

Recently, large-format LIBs have a problem with product life due to temperature deviation. In this study, a three-dimensional electrochemical-thermal coupled model of 55 Ah large-format LIBs is used to analyze the effect of cell aspect ratios, tab locations, and C-Rates on thermal behavior during discharge. Results show that when the cell aspect ratio becomes far from 2.15, heat generation becomes non-uniform and the temperature deviation increases. The closer the tabs are located, the more temperature deviation increases. The effect of cell aspect ratio and tab location on temperature deviation is increased as higher C-Rate. Also, the effect of cell aspect ratio on the temperature deviation of LIB is larger than tab location. The main cause of temperature deviation comes from different heat generation of each component of the LIB, which is reversible heat and irreversible heat (Joule heat). The influence of irreversible heat is dominant at higher C-rate. Therefore, at higher C-rate, the temperature deviation is effectively reduced by adjusting the cell aspect ratio and tab location that affect current density distribution. In this study, the minimum temperature standard deviation is shown when the cell aspect ratio is 2.15 and negative-positive tabs are located on the opposite side of the cell.