An Energy Storage Solution That Combines Polymers And Nano-films

According to a team of researchers from Pennsylvania State University, a new type of lightweight composite material can be used for energy storage in flexible electronic equipment, electric vehicles, and aerospace applications. Much higher than the current commercial polymers. This polymer-based ultra-thin material can be produced using technologies that are already available in industry.

Qing Wang, a professor in the Department of Materials Science and Engineering at Pennsylvania State University, said: "This is part of a series of work we have done in the high-temperature dielectric laboratory for capacitors. Prior to this work, we have developed a boron nitride nanosheet and Dielectric polymer composite materials, but realize that there are still scale issues to achieve economies of scale."

Scalability or the manufacture of advanced materials on commercially relevant equipment has always been a challenge for many new two-dimensional materials developed by academic laboratories.

"From the perspective of soft materials, 2D materials are fascinating, but how to mass-produce them is a problem," Wang said. In addition, being able to combine them with polymeric materials is a key feature of future flexible electronic applications and electronic devices. "

In order to solve this problem, the laboratory cooperated with a team from Pennsylvania State University to conduct related research on two-dimensional crystals.

"This work was established in a conversation with a graduate student. The graduate student is Amin Azizi, Wang's graduate student Matthew Gadinski," said Nasim Alem, an assistant professor at the Center for Materials Science and Engineering, University of Pennsylvania. . "This is the first powerful experiment in which a soft polymer material is combined with a hard 2D crystal material to create a functional dielectric device."

Azizi is now a postdoctoral researcher at the University of California, and Gadinski is now a senior engineer at The Dow Chemical Company. They have developed a technique that can use chemical vapor deposition to transfer multilayer hexagonal boron nitride nanocrystalline films and films to polyether acyl Both sides of the imine (PEI) membrane. They used pressure to bond the three-layer sandwich structure material together. The researchers were surprised that pressure alone, without any chemical bonds, was enough to make an independent film strong enough to be manufactured in a high-throughput roll-on-roll process.

This result was published in the most recent issue of the "Advanced Materials" magazine, the paper is titled "High-performance polymers, with chemical vapor deposited hexagonal boron nitride as a scalable high-temperature dielectric material."

Hexagonal boron nitride is a wide band gap material with high mechanical strength. Its wide band gap makes it a good insulator, protecting the PEI film from dielectric breakdown at high temperatures, which is also the reason for the failure of other polymer capacitors. At operating temperatures above 176 degrees Fahrenheit, the current best commercial polymers begin to lose efficiency, but hexagonal boron nitride coated PEI can work efficiently at 392 degrees Fahrenheit. Even at high temperatures, the coated PEI remains stable during 55,000 charge-discharge cycles.

"In theory, all these polymers exhibit high performance and have high commercial value. They can be coated with a layer of boron material to prevent charge injection," Wang said. "I think this will make this technology feasible in future commercialization."

Alem said, “There are many equipment made using two-dimensional crystals in the laboratory, but defects make them have manufacturing problems. There is a large band gap material, such as boron nitride, which does a good job, despite the small microstructure The function may not be ideal.

First-principles calculations have determined the electronic barrier. The metal electrode applied to the structure and interface of the PEI/hexagonal boron nitride provides a significantly higher current than the dielectric polymer contact form of the typical metal electrode, making it more difficult Use electrode injection to achieve charging. This work was completed by the research team of Professor Long-Qing Chen and Professor Donald W. Hamer of Materials Science and Engineering at the University of Pennsylvania.