PFI:AIR - TT: Novel High Temperature and High Energy Density Polycarbonate/Nylon Multilayer Films for Electric Vehicles Applications

本次PFI：空气技术转化项目致力于转化凯斯西储大学(CWRU)发现的多层介电薄膜技术，以满足电动汽车(EDV)对高性能、低成本的聚合物薄膜电容器的需求。EDVS的优势在于全面减少了人口稠密城市的温室气体排放和污染。电动汽车需要一个电力电子系统来操作最终推动汽车的电机。电力电子系统需要直流电容器来正确控制电机以响应来自驾驶员的速度指令。目前EDV电力电子设备中的直流连接电容器使用双向拉伸聚丙烯(BOPP)薄膜。然而，BOPP薄膜电容器的能量密度相对较低，额定温度为85°C，因此，目前的EDV需要大量的BOPP薄膜电容器和水冷却系统，从而导致电力电子单元的总体成本较高。为了克服这一经济劣势，迫切需要开发新的高性能电容器薄膜，这种薄膜具有更高的能量密度，可以高效地运行到150°C，从而潜在地完全消除冷却系统，并导致更小的尺寸和质量系统。在NSF科学技术中心、分层聚合物材料中心(CLIPS)的支持下，CWRU发明了一种独特的多层介质薄膜技术。在该技术中，使用多层共挤出技术将高温、高击穿强度和低损耗的介电聚合物(例如，聚碳酸酯，PC)与高能量密度的聚合物(例如，聚偏氟乙烯，PVDF)多层地形成层状配置。研究发现，在一个系统中可以同时获得高能量密度、耐高温和低损耗的介电性能。因此，这种多层膜技术的创新之处在于，在不合成和开发新聚合物的情况下，只需使用商业上可用的聚合物就可以实现新的介电材料。因此，可以预见更短的商业化道路。在已有的PC/PVDF多层膜研究成果的基础上，本项目旨在用一类价格便宜但能量密度仍然较高的偶数尼龙纤维替代PVDF用于高温PC多层膜。在这个项目中，由CWRU和两家小企业PolymerPlus，LLC和SB Electronics，Inc.(SBE)组成的PFI Air团队提议将PC/尼龙多层介质膜技术转化为适用于EDV的高温高性能直流连接电容器。具体地说，CWRU将开展薄膜级别的基础研究，以确定PC/尼龙多层薄膜的最佳配方。PolymerPlus将使用这种配方并将薄膜生产扩大到无皱薄膜卷。在适当的金属化后，PolymerPlus将向SBE供应金属化薄膜辊，以封装成原型薄膜电容器。与BOPP电容器相比，这些电容器原型的性能将由团队进行测试。该研究项目将为研究生和本科生提供理想的培训机会，因为他们可以与这两家小企业的专家合作，学习技术翻译和商业化途径。如果成功，该团队将能够利用该项目的成果，并与EDV制造商联系，进一步将多层介电薄膜技术商业化。

This PFI: AIR Technology Translation project focuses on translating the multilayer dielectric film technology discovered at Case Western Reserve University (CWRU) to fulfill the need of high performance and low cost polymer film capacitors for electric drive vehicles (EDVs). The advantage of EDVs lies in the overall reduction of greenhouse gas emissions and pollution in heavily populated cities. Electric drive vehicles require a power electronics system to operate the motor that ultimately moves the car. The power electronics system requires DC-link capacitors to properly control the motor in response to speed commands from the driver. Current DC-link capacitors in the power electronics of EDVs use biaxially oriented polypropylene (BOPP) films. However, BOPP film capacitors have relatively low energy density and a low temperature rating of 85°C. Thus, a large volume of BOPP film capacitors and a water-cooling system are necessary in present EDVs, contributing to a high overall cost of the power electronics unit. To overcome this economic disadvantage, it is highly desired to develop new high performance capacitor films, which have a higher energy density and can operate efficiently up to 150 °C, thus potentially eliminately the cooling system entirely and resulting in a smaller size and mass system.Supported by the NSF Science and Technology Center, Center for Layered Polymeric Materials (CLiPS), a unique multilayer dielectric film technology was invented at CWRU. In this technology, a high temperature, high breakdown strength, and low loss dielectric polymer (e.g., polycarbonates, PC) is multilayered with a high energy density polymer (e.g., poly(vinylidene fluoride), PVDF) into a layered configuration using the multilayer coextrusion technique. It is found that high energy density, high temperature tolerance, and low loss dielectric properties can be achieved simultaneously in one system. Therefore, the innovation of this multilayer film technology lies in the fact that without synthesizing and developing new polymers, new dielectric materials can be achieved simply by employing commercially available polymers. Consequently, a shorter commercialization pathway can be anticipated. On the basis of existing results on PC/PVDF multilayer films, this project aims to replace PVDF with a class of cheaper, but still high energy density, even-numbered nylons in multilayer films with high temperature PC. Preliminary results indicate that high energy density, high temperature tolerance, and low loss can also be achieved in the PC/nylon multilayer films.In this project, a PFI AIR team, comprised of CWRU and two small businesses: PolymerPlus, LLC and SB Electronics, Inc. (SBE), proposes to translate the PC/nylon multilayer dielectric film technology into high temperature and high performance DC-link capacitors for EDVs. Specifically, CWRU will carry out film-level fundamental research to determine the optimal formulation of the PC/nylon multilayer films. PolymerPlus will use this formulation and scale up the film production into wrinkle-free film rolls. After appropriate metallization, PolymerPlus will supply the metallized film rolls to SBE to package into prototype film capacitors. The performance of these capacitor prototypes in comparison with BOPP capacitors will be tested by the team. This research project will offer ideal training opportunities for both graduate and undergraduate students because they can work with experts in the two small business companies and learn the technology translation and commercialization pathways. If successful, the team will be able to use the outcomes from this project and connect to EDV manufacturers for further commercialization of the multilayer dielectric film technology.