Design optimization of tab attachment positions and cell aspect ratio to minimize temperature difference in 45-Ah LFP large-format lithium-ion pouch cells

Abstract

Large-format lithium-ion battery (LIB) cells have limitations such as reduced safety and life due to the large temperature difference in the cells. Thus, in this study, the tab type, tab attachment positions, and cell aspect ratio, which determine the shape of the LIB cell, were optimized to minimize the temperature difference in a 45-Ah lithium iron phosphate(LFP)/graphite large-format cell. As a constraint, the area of the LIB cell was kept constant to maintain a constant capacity of the LIB cell. A 3D electrochemical–thermal model was used to calculate the temperature distribution in the LIB cell. By optimizing the cell aspect ratio, tab type, and tab attachment positions, the temperature difference was minimized because of the decreased internal resistance, and the cell life increased owing to the reduced temperature difference. Moreover, the optimized cell design showed a 7.3% lower discharge capacity reduction than that of the initial design at 1000 cycles. Results show that optimization is an effective method to minimize the temperature difference in large-format LIBs and enhance their life.