17年8月2日
A new, lightweight composite material for energy storage in flexible electronics, electric vehicles and aerospace applications has been experimentally shown to store energy at operating temperatures well above current commercial polymers, according to a team of Penn State scientists. This polymer-based, ultrathin material can be produced using techniques already used in industry.
"This is part of a series of work we have done in our lab on high-temperature dielectrics for use in capacitors," said Qing Wang, professor of materials science and engineering, Penn State. "Prior to this work we had developed a composite of boron nitride nanosheets and dielectric polymers, but realized there were significant problems with scaling that material up economically."
可扩展性 - 或以设备的商业相关量中的高级材料，这是许多新的二维材料在学术实验室中开发的许多新的挑战。王说：“从软材料的角度来看，2D材料令人着迷，但是如何批量产生它们是一个问题。”“此外，能够将它们与聚合物材料相结合是将来柔性电子应用和电子设备的关键功能。”
为了解决这个问题，王的实验室与宾夕法尼亚州立大学的一群人合作。“这项工作是在我的研究生Amin Azizi和Wang博士的研究生Matthew Gadinski之间进行的对话，”宾夕法尼亚州立大学二维和宾夕法尼亚州立大学中心的材料科学与工程助理教授Nasim Alem说。分层材料。“这是第一个强大的实验，其中软聚合物材料和坚硬的2D晶体材料聚集在一起，以创建功能介电设备。”
Azizi, now a post-doctoral fellow at University of California—Berkeley, and Gadinski, now a senior engineer at DOW Chemical, developed a technique using chemical vapor deposition to make multilayer, hexagonal boron-nitride nanocrystal films and transfer the films to both sides of a polyetherimide (PEI) film. They next bonded the films together using pressure into a three-layer sandwich structure. In a result that was surprising to the researchers, pressure alone, without any chemical bonding, was enough to make a free-standing film strong enough to potentially be manufactured in a high-throughput roll-to-roll process.
结果在最近的一期期刊上报道了Advanced Materialsin a paper titled "High-performance Polymers Sandwiched with Chemical Vapor Deposited Hexagonal Boron Nitrides as Scalable High-Temperature Dielectric Materials."
六角硼硝化物是一种具有高机械强度的宽带隙材料。它的宽带间隙使其成为一个很好的绝缘体，并保护PEI膜免受高温下介电击穿的侵蚀，这是其他聚合物电容器失败的原因。在高于176华氏度的工作温度下，当前最佳的商业聚合物开始降低效率，但是六边形硝酸盐涂层的PEI可以以高效率在392度的华氏度下以高效率运行。即使在高温下，涂层的PEI在测试中仍保持超过55,000个电荷释放周期的稳定。
"Theoretically, all these high-performance polymers that are so commercially valuable can be coated with boron nanosheets to block charge injection," Wang said. "I think this will make this technology feasible for future commercialization."
Alem added, "There are many devices made with 2D crystals at the laboratory scale, but defects make them a problem for manufacturing. With a large band-gap material like boron nitride, it does a good job despite small microstructural features that might not be ideal."
采用基于计算确定electron barrier, established at the interface of the PEI/hexagonal boron-nitride structure and the metal electrodes applied to the structure to deliver, current is significantly higher than typical metal electrode-dielectric polymer contacts, making it more difficult for charges from the electrode to be injected into the film. This work was done by the theoretical research group of Long-Qing Chen, Donald W. Hamer Professor of Materials Science and Engineering, professor of engineering science and mechanics, and mathematics, Penn State.
其他为这项工作做出贡献的人包括博士后学者Qi Li和王的研究生Feihua Liu；艾姆实验室中的穆罕默德·阿布·阿尔索（Mohammed Abu Alsaud）本科生；高级科学家Jianjun Wang，博士后学者Yi Wang和研究生Bo Wang都在Chen Group中。美国海军研究办公室和国家科学基金会支持这项工作。
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