Development of high-performance Li batteries with autonomic thermal regulation of their performance by encapsulated nanosized phase change materi

相变材料(PCM)是一组用于热管理的高效材料，不需要外部热调节系统。当环境温度发生变化时，相变材料利用潜热储存和释放热能。相变材料以前曾用于建筑材料和一些电子产品，以维持运行期间的温度，以及在太阳能部门的广泛使用。在本项目中，将使用无机盐水合物(AxBy.n(H2O))和低熔点金属作为固液相变材料，自动调节锂离子电池的内部温度。目前，外部冷却系统用于防止锂离子电池达到危险温度(60摄氏度以上)，防止热失控。在外部冷却系统中使用相变材料将工作温度维持在25到30摄氏度之间的尝试有限，这将是锂离子电池的最佳工作温度。无机相变材料的单位体积储热能力是有机相变材料的两倍，而且与有机相变材料相比也更便宜；使其成为研究的理想对象。当盐类水合物发生相变，失去部分或全部水分时，潜热就会被吸收。当盐水合物重新结晶时，潜热就会释放出来。使用无机相变材料存在以下问题：相变过程中体积变化、导热性能差、过冷和腐蚀性。可以使用成核剂等添加剂来减少过冷。对于其他回撤，可以应用封装方法。封装可用于保护PCM和容器不泄漏，以及应用于外壳的附加功能，如增加导热系数。纳米核壳相变材料具有更大的表面积与体积比，因此具有极高的换热效率。本项目的目的是使用纳米包覆的核壳无机相变材料来保持锂离子电池的内部温度。封装的相变材料将被直接插入电池中以保持热量。该项目的目标是使用封装的相变材料来调节电池的内部温度，使其温度在25-30摄氏度之间，以优化性能。如果成功，人们希望封装的PCM将减少对外部冷却系统的需求，这些外部冷却系统会增加现有电池系统的额外质量和应变，使它们更高效。

Phase change materials (PCMs) are an efficient group of materials for use in thermal management without the need for an external thermal regulation system. PCMs take advantage of latent heat to store and release thermal energy when a phase change occurs due to a change in temperature to the surroundings. PCMs have been previously applied to building materials and some electronics to sustain temperatures during operation as well as extensive use in the solar energy sector. In this project, inorganic salt hydrates (AxBy.n(H2O)) and metals with low melting points will be used as solid-liquid PCMs to automatically regulate the internal temperature of a lithium-ion battery. Currently, external cooling systems are used to prevent lithium ion batteries from reaching dangerous temperature (above 60C) preventing thermal runaway. There have been limited attempts to use PCMs in external cooling systems to sustain working temperatures between 25 and 30C which would be optimal for Li-ion batteries.Inorganic PCMs have double the heat storage capacity per unit volume and are also cheaper in comparison to their organic counter parts; making them an ideal candidate for investigation. Latent heat is absorbed when the salt hydrates undergo a phase change losing part or all of their waters. Latent heat is then released when the salt hydrate is recrystalised. There are issues with using inorganic PCMs: change of volume during phase change, poor thermal conductivity, supercooling and corrosive properties. Additives, such as nucleating agents can be used to reduce supercooling. For the other draw backs, encapsulation methods can be applied. Encapsulation can be useful to protect the PCM and the container from leaking as well as additional functionality, such as increased thermal conductivity, being applied to the shell. Nanosized core shell PCMs have a greater surface to volume ratio and so are extremely efficient for heat transfer.The aim of this project is to use nanosized encapsulated core shell inorganic PCMs to maintain the internal temperature of a lithium ion battery. The encapsulated PCMs will be inserted directly into the battery to maintain heat. The objective of the project would be to use encapsulated PCMs to regulate the internal temperature of a battery between 25-30C to optimise performance. If successful, it is hoped the encapsulated PCMs would reduce the need for external cooling systems that add additional mass and strain to current battery systems making them more efficient.