Cell- and Pack-Level Simulation of Large-Format Li-Ion Battery Safety Events

Abstract

Owing to their unsurpassed energy density, lithium ion batteries have been adopted for hybridized vehicles, such as the Chevy Volt and the Nissan Leaf, in the aerospace industry, and in stationary energy storage applications. However, as highlighted by several recent high profile safety events, significant challenges remain for the widespread adoption of Li-ion technology in automotive and aerospace applications. These documented safety incidents have been driven by both cell-level and pack level events, and as such, accurate simulation of safety events on both the cell and pack level is needed for fundamental understanding of the underlying physics and safety-conscious design. [1,2,3,4].In this work, using commercially available AutoLion™ software, we demonstrate cell- and pack-level electrochemical/thermal coupled simulation of various types of safety events, including nail penetration, external short, and internal short. Figures 1 and 2 highlight two types of such safety simulations performed. Figure 1 gives the peak temperature of all four cells in a four-cell pack nail penetration; this simulation highlighting the hotter temperature of the interior cells during multi-cell short. Figure 2 illustrates the voltage and current response of an externally-shorted 25Ah L-ion ion cell. In our presentation, we elucidate on the physics of these shorts on both the cell- and pack-level, and demonstrate how simulation can be used to screen various cell and pack designs for safe implementation of safe Li-ion battery technologies. Acknowledgements Partial support of this work by DOE CAEBAT2 program is greatly acknowledged.