Analysis of Heat-Spreading Thermal Management Solutions for Lithium-Ion Batteries

The analysis and optimization of thermal performance of Li-ion battery packs are topics of great interest today. Most Li-ion batteries for motive, vehicular, backup power and utility energy storage applications are fitted with a microprocessor-controlled thermal management system including an array of temperature and voltage sensors and an active cooling system. However, as the complexity of the thermal management system increases, so does its weight, volume and parasitic power consumption, all factors that adversely affect the vehicle’s performance. In this sense, an improved thermal management system based on including passive solutions such as phase change materials or heat spreading technologies could decrease the load on active components and ultimately the weight and costs of the system. This paper describes an experimental and simulation study aimed at evaluating the effectiveness of flexible graphite materials for heat spreaders in battery thermal management systems. A commercial Li-ion battery pack for power tools applications was adopted as a case study. The electro-thermal behavior of the battery pack was characterized through combined experimental investigation and 3D FEM modeling to determine the heat generation rate of the battery cells during utilization and to evaluate the thermal behavior of the battery pack. A thermal management solution based on flexible graphite heat spreading material was then designed and implemented. The paper presents a comparative study conducted in simulation to evaluate the improvements in the pack thermal behavior.