Non-uniform thermal characteristics investigation of three-dimensional electrochemical-thermal coupled model for pouch lithium-ion battery

Recently, lithium-ion batteries have been preferred as an approach for energy infrastructures. However, its uneven performance directly affects battery modeling, parameter estimation and thermal management. To understand the non-uniform thermal characteristics of pouch battery, a three-dimensional multiphysics model that combines an electrochemical model and a thermal model is developed in this study. Here, three models with lumped and non-uniform heat source as well as temperature are comprehensively compared and evaluated under different discharge rates. Results indicate that the dimensionality and lumped-source of model have negligible effects on predicting heat generation and maximum temperature, but the temperature gradient distribution shows deviation of 64.0/62.1% at 5 C discharge. Due to the uneven heat generation, an overheating region appears along the battery center to positive tab, especially at high discharge rates. What's more, it is found that more heat is generated at a high discharge rate and low-temperature, which leads to higher temperature rise and temperature gradient. In addition, the critical heat transfer coefficient that represents the critical heat dissipation capacity of thermal management system is estimated. These findings can provide insights into the selection of battery models and the design of thermal management systems in accordance with different scenarios.