核壳结构热安全相变材料的设计及其对锂离子电池的安全防护机理研究

With the widely application and rapid development of lithium ion battery (LIB) in the fields of electronic products, energy storage and electric vehicles, the safety issues have been paid more and more attention. To solve the safety issues caused by the thermal runaway of LIB, cole-shell structure thermal safe phase change material with dual function of heat storage and fire extinguishing are designed and prepared. This material will protect LIB in the initial safety risk stage and the later thermal runaway stage. We try to prepare various thermal safe phase change material by the fluorinated modification and material selection, and study the effect of molecular structure on the heat storage and fire extinguishing properties. We plan to prepare cole-shell structure thermal safe phase change material by microencapsulation technology, to study the effects of different shell materials on the mechanical properties and thermal stability of microcapsules. Also we will study the heat-conducting property of cole-shell structure thermal safe phase change material, and explore the heat storage efficiency in lithium ion battery. Then we will investigate the compatibility of cole-shell structure thermal safe phase change material with electrolyte and the effect on the LIB electrochemical properties, and probe the rules of cole-shell structure change and function transformation from heat storage to fire extinguishing, to reveal the mechanism of the safety protection for LIB. The implementation of this project could establish a theoretical and experimental basis for the development of safe and reliable lithium ion battery.

随着锂离子电池在电子产品、储能和动力汽车等领域的迅速普及和快速发展，其安全问题越来越受到社会的广泛关注。本项目针对锂离子电池热失控引发的安全性问题，设计合成具有储热-灭火双功能的核壳结构热安全相变材料，从锂离子电池安全隐患的初期和热失控后期不同阶段的双重作用实现对锂离子电池的热安全防护。通过氟化改性和氟化物选择获得多种结构的热安全相变材料，研究分子结构对储热灭火性能影响；利用微胶囊化技术制备核壳结构热安全相变材料，研究不同壳层材料对微胶囊的力学性能和热稳定性的影响；研究核壳结构热安全相变材料的导热性能，探讨其在锂离子电池中的储热效率；研究核壳结构热安全相变材料与电解液相容性，以及应用于锂离子电池对电化学性能的影响，探讨随温度的升高核壳结构变化规律以及热安全相变材料从储热向灭火功能转化规律，揭示核壳结构热安全相变材料对锂离子电池的安全防护机理，为开发安全可靠锂离子电池提供理论依据和实验基础。

针对锂离子电池热失控引发的安全性问题，本项目设计合成具有储热、灭火功能的核壳结构热安全相变材料，从而对锂离子电池进行热安全防护。具体研究成果如下：合成含氟含磷不燃化合物，对热安全相变材料的多种含氟含磷化合物芯材进行比较选择，制备DHDP@UF+Paraffin@MF等核壳结构热安全相变材料；研究核壳结构热安全相变材料在电解液中的高效阻燃作用，以及对锂离子电池电化学性能的影响；研究核壳结构热安全相变材料在锂离子电池中抑制燃烧、降低热释放和锂枝晶抑制等性能，揭示核壳结构热安全相变材料对锂离子电池的安全防护机理。本项目的实施将为锂离子电池的热安全防护提供实验基础和理论依据。