Numerical study on the air-cooled thermal management of Lithium-ion battery pack for electrical vehicles

Abstract

A Lithium-ion battery is one of the most common batteries being widely used as the power source in Electric Vehicle (EV) due to its high energy density, power density, long life span and environment friendly. Due to the high power requirement of EV, thousands of cylindrical Lithium-ion battery cells are typically connected in parallel and/or series forming a battery pack. This significantly generates enormous heat through the internal resistance effect and exothermic reactions inside the battery during the charge or discharge process. If the fetal heat cannot be dissipated sufficiently, the battery cells may encounter capacity fade, thermal runaway and instability issues. Thus, efficient thermal management of the Lithium-ion battery pack is essential to restrain high temperature and non-uniformity of temperature in the battery pack. This issue remains a challenge, although much research has been conducted on this topic. In this work, the air cooling thermal management system is numerically investigated due to lower manufacturing cost, simple layout requirements and higher reliability of the system. A transient three-dimensional heat transfer model of the cylindrical Lithium-ion battery pack is developed to study the effect of the inlet velocity, discharge rate and cell arrangement structure on the cooling performance. The proposed system is designed to minimize the maximum cell temperature and the cell temperature uniformity. The simulated results can be further applied as a reference in designing the structures of the battery pack and planning the cooling strategies.