Volume 4: Innovative Solutions for Energy Transitions: Part III

Understanding the Electrochemical/Thermal Performance of a Large-format Li-ion Pouch Cell via a Scaling Analysis Approach Jie Lin, Howie N. Chu, Charles W. Monroe, David Howey

Abstract

Thermal management of large-format Li-ion cells is crucial due to their spatial- and temperature-dependent electrochemical reaction kinetics and heat generation. However, existing battery modeling mostly employs a pseudo-2D model which is not able to capture the local current density and temperature across the entire cell geometry. Therefore, in this paper, we propose a simplified 3D electrochemical/thermal model to investigate the temperature and voltage responses of a Li-ion pouch cell. Concurrently, a lock-in thermography experiment is conducted. The model can achieve good accuracy in predicting the surface temperature and cell voltage of the battery during cycling. A scaling analysis is subsequently carried out to determine the dimensionless numbers that affect the battery performance. The proposed approach helps to facilitate a fundamental understanding of the dominant mechanisms related to voltage polarization, heat generation and temperature non-uniformity.

Keywords energy storage, Li-ion battery, electrochemistry, thermodynamics