Optimization of LFP Pouch Cell Tab Design for Uniform Temperature Distribution

Abstract

An increase in the size of large-format Li-ion batteries (LIBs) may lead to nonuniform temperature distribution, which degrades the performance and lifespan of the LIBs. To address this issue, we performed design optimization using a 3D electrochemical-thermal coupled model for 55 Ah LFP/graphite large-format pouch cells. To minimize temperature differences in Normal Tab (NT), Lateral Tab (LT), and Counter Tab (CT) types of LIBs, design optimization was performed on the width, height, and attachment position of each positive and negative Table The upper and lower limits of each design variable were set as constraints without exceeding the sum of the total area of the tabs of the initial NT type. Owing to the optimization of the NT, LT, and CT types, the temperature difference in the optimized CT type was 79.2% less than in the initial NT type. Additionally, the potential difference decreased by 37.1%, minimizing ohmic heat. Aging analysis of 2500 cycles was performed to analyze the improvement in the lifespan due to the uniform temperature distribution. Consequently, the capacity retention rate of the optimized CT type was 6.5% higher than that of the initial NT type. Thus, the temperature distribution and lifespan of LIBs were improved by design optimization.

Keywords

• large-format lithium-ion battery
• 3D electrochemical-thermal model
• tab size
• tab attachment position
• temperature difference
• optimization