面向低温环境锂离子电池高效热管理的碳基导电复合相变材料温控特性研究

Lithium ion battery has a wide application in military or civilian equipment. But the operation temperature greatly affect the Li-ion battery performance. A well designed thermal management system that controls the battery within the optimal temperature range ensures the battery to work efficiently and safely. This project focuses on the thermal management system using phase change materials (PCMs). We plan to prepare electric conductive PCMs and utilize the Joule heat effect of the PCM to heat up the battery that operated under low temperatures by connecting the PCMs into an electric circuit. The PCMs also can cool the battery down when the battery work and produce a large amount of heat. To achieve this goal, we first study the relationship between the composition of the carbon-based composite PCM and its electric conductivity. After knowing how to prepare such an electric conductive PCM, we will study how its electric properties, thermal properties and the electric potential distribution will affect the battery temperature and electrochemical performance. At last, we will develop a numerical model that couples the battery heating source, heat transfer and storage in the PCMs and electric heating of PCMs. This model helps analyze the heat transfer mechanism inside the PCM-based thermal management system and provide guides on the system design and optimization. This project solves the problem that the PCM is unable to heat the battery and develop a highly efficient thermal management system in which the heating and cooling are integrated into one material. We also develop a new model for this kind of system. This novel thermal management system is suitable for the battery operated at all climate, which is a definite step forward in the PCM-based battery thermal management technology.

锂离子电池在军用、民用设备电源系统中应用广泛，但其性能受温度影响显著。为保障电池高效、安全工作，必须设计高效热管理系统维持电池处于最佳工作温度。本项目以高性能相变材料热管理系统为研究对象，提出通过导电相变材料高效的电热转化过程在低温环境下快速加热电池，同时利用相变材料储热能力为电池提供高温散热冷却。为此，本项目首先研究碳基高电导复合相变材料组成与其电导率调控规律，掌握导电复合相变材料的制备方法；通过研究相变材料电物性、热物性以及电场结构与电池温度及电化学性能相互作用规律，掌握电池低温启动阶段的电加热过程以及电池工作放热阶段冷却过程调控方法；最后建立耦合电池产热、相变传热、电场加热的新型数学模型，分析电加热系统内产热和传热机理，指导相变材料组成及系统结构优化。本研究突破了相变材料无法加热电池的瓶颈，实现了全温度段内电池加热冷却一体化结构，构建了新型传热模型，将有力推进电池热管理技术进步。