Study of relationship between temperature and thermal energy, operating conditions as well as environmental factors in large-scale lithium-ion batteries

We have developed a thermal model for a large-scale lithium-ion cell and have simulated its thermal behaviors during charge, discharge, and charge-discharge cycles with different current rates by using the software of COMSOL Multiphysics 3.5a. In this work, thermal energy and its distribution were firstly calculated based on experimental data under different operating conditions. A new parameter, called thermal energy conversion efficiency, was proposed to describe relative value of thermal energy in the cell. The thermal energy conversion efficiency and the temperature were plotted in a figure to show their relativity. The temperature variation was also studied systemically when the cell underwent discharge-charge cycles. A low rate charge is validated to be a favorable factor in protecting the cell from overheating during charge-discharge cycles. A connection resistance is proved to be a main factor that accelerates the rise of temperature in the spot near a terminal column, which should be eliminated as much as possible to protect the cell from local overheating. Copyright (c) 2014 John Wiley & Sons, Ltd.