A team of UCF scientists has developed a new process for creating flexible supercapacitors that can store more energy and be recharged more than 30,000 times without degrading.
The novel method from the University of Central Florida’s NanoScience Technology Center could eventually revolutionize technology as varied as mobile phones and electric vehicles.
“If they were to replace the batteries with these supercapacitors, you could charge your mobile phone in a few seconds and you wouldn’t need to charge it again for over a week,” said Nitin Choudhary, a postdoctoral associate who conducted much of the research published recently in the academic journal ACS Nano.
Anyone with a smartphone knows the problem: After 18 months or so, it holds a charge for less and less time as the battery begins to degrade.
Scientists have been studying the use of nanomaterials to improve supercapacitors that could enhance or even replace batteries in electronic devices. It’s a stubborn problem, because a supercapacitor that held as much energy as a lithium-ion battery would have to be much, much larger.
The team at UCF has experimented with applying newly discovered two-dimensional materials only a few atoms thick to supercapacitors. Other researchers have also tried formulations with graphene and other two-dimensional materials, but with limited success.
“There have been problems in the way people incorporate these two-dimensional materials into the existing systems – that’s been a bottleneck in the field. We developed a simple chemical synthesis approach so we can very nicely integrate the existing materials with the two-dimensional materials,” said principal investigator Yeonwoong “Eric” Jung, an assistant professor with joint appointments to the NanoScience Technology Center and the Materials Science & Engineering Department.
Jung’s team has developed supercapacitors composed of millions of nanometer-thick wires coated with shells of two-dimensional materials. A highly conductive core facilitates fast electron transfer for fast charging and discharging. And uniformly coated shells of two-dimensional materials yield high energy and power densities.
Scientists already knew two-dimensional materials held great promise for energy storage applications. But until the UCF-developed process for integrating those materials, there was no way to realize that potential, Jung said.
“For small electronic devices, our materials are surpassing the conventional ones worldwide in terms of energy density, power density and cyclic stability,” Choudhary said.
Cyclic stability defines how many times it can be charged, drained and recharged before beginning to degrade. For example, a lithium-ion battery can be recharged fewer than 1,500 times without significant failure. Recent formulations of supercapacitors with two-dimensional materials can be recharged a few thousand times.
By comparison, the new process created at UCF yields a supercapacitor that doesn’t degrade even after it’s been recharged 30,000 times.
Jung is working with UCF’s Office of Technology Transfer to patent the new process.
Supercapacitors that use the new materials could be used in phones and other electronic gadgets, and electric vehicles that could benefit from sudden bursts of power and speed. And because they’re flexible, it could mean a significant advancement in wearable tech, as well.
“It’s not ready for commercialization,” Jung said. “But this is a proof-of-concept demonstration, and our studies show there are very high impacts for many technologies.”
A team of UCF researchers has produced the most efficient quantum cascade laser ever designed – and done it in a way that makes the lasers easier to manufacture.
Quantum cascade lasers, or QCLs, are tiny – smaller than a grain of rice – but they pack a punch. Compared to traditional lasers, QCLs offer higher power output and can be tuned to a wide range of infrared wavelengths. They can also be used at room temperature without the need for bulky cooling systems.
But because they’re difficult and costly to produce, QCLs aren’t used much outside the Department of Defense.
A University of Central Florida team led by Assistant Professor Arkadiy Lyakh has developed a simpler process for creating such lasers, with comparable performance and better efficiency. The results were published recently in the scientific journal Applied Physics Letters.
“The previous record was achieved using a design that’s a little exotic, that’s somewhat difficult to reproduce in real life,” Lyakh said. “We improved on that record, but what’s really important is that we did it in such a way that it’s easier to transition this technology to production. From a practical standpoint, it’s an important result.”
That could lead to greater usage in spectroscopy, such as using the infrared lasers as remote sensors to detect gases and toxins in the atmosphere. Lyakh, who has joint appointments with UCF’s NanoScience Technology Center and the College of Optics and Photonics, envisions portable health devices. For instance, a small QCL-embedded device could be plugged into a smartphone and used to diagnose health problems by simply analyzing one’s exhaled breath.
“But for a handheld device, it has to be as efficient as possible so it doesn’t drain your battery and it won’t generate a lot of heat,” Lyakh said.
The method that previously produced the highest efficiency called for the QCL atop a substrate made up of more than 1,000 layers, each one barely thicker than a single atom. Each layer was composed of one of five different materials, making production challenging.
The new method developed at UCF uses only two different materials – a simpler design from a production standpoint.
Two scientists at the University of Central Florida have discovered how to get a solid material to act like a liquid without actually turning it into liquid, potentially opening a new world of possibilities for the electronic, optics and computing industries.
When chemistry graduate student Demetrius A. Vazquez-Molina took COF-5, a nano sponge-like, non-flammable manmade material and pressed it into pellets the size of a pinkie nail, he noticed something odd when he looked at its X-ray diffraction pattern. The material’s internal crystal structure arranged in a strange pattern. He took the lab results to his chemistry professor Fernando Uribe-Romo, who suggested he turn the pellets on their side and run the X-ray analysis again.
The result: The crystal structures within the material fell into precise patterns that allow for lithium ions to flow easily – like in a liquid.
The findings, published in the Journal of the American Chemical Societyearlier this summer, are significant because a liquid is necessary for some electronics and other energy uses. But using current liquid materials sometimes is problematic.
For example, take lithium-ion batteries. They are among the best batteries on the market, charging everything from phones to hover boards. But they tend to be big and bulky because a liquid must be used within the battery to transfer lithium ions from one side of the battery to the other. This process stores and disperses energy. That reaction creates heat, which has resulted in cell phones exploding, hover boards bursting into flames, and even the grounding of some airplanes a few years ago that relied on lithium batteries for some of its functions.
But if a nontoxic solid could be used instead of a flammable liquid, industries could really change, Uribe-Romo said.
“We need to do a lot more testing, but this has a lot of promise,” he said. “If we could eliminate the need for liquid and use another material that was not flammable, would require less space and less packaging, that could really change things. That would mean less weight and potentially smaller batteries.”
Smaller, nontoxic and nonflammable materials could also mean smaller electronics and the ability to speed up the transfer of information via optics. And that could mean innovations to communication devices, computing power and even energy storage.
“This is really exciting for me,” said Vazquez-Molina who was a pre-med student before taking one of Uribe-Romo’s classes. “I liked chemistry, but until Professor Romo’s class I was getting bored. In his class I learned how to break all the (chemistry) rules. I really fell in love with chemistry then, because it is so intellectually stimulating.”
Uribe-Romo has his high school teacher in Mexico to thank for his passion for chemistry. After finishing his bachelor’s degree at Instituto Tecnológico y de Estudios Superiores de Monterrey in Mexico, Uribe-Romo earned a Ph.D. at the University of California at Los Angeles. He was a postdoctoral associate at Cornell University before joining UCF as an assistant professor in 2013.
Learn more: UCF Team Tricks Solid Into Acting as Liquid
A finding by a University of Central Florida researcher that unlocks a means of controlling materials at the nanoscale and opens the door to a new generation of manufacturing is featured online today in the journal Nature.
Using a pair of pliers in each hand and gradually pulling taut a piece of glass fiber coated in plastic, associate professor Ayman Abouraddy found that something unexpected and never before documented occurred – the inner fiber fragmented in an orderly fashion.
“What we expected to see happen is NOT what happened,” he said. “While we thought the core material would snap into two large pieces, instead it broke into many equal-sized pieces.”
He referred to the technique in the Nature article as “Breaking Me Softly.”
The process of pulling fibers to force the realignment of the molecules that hold them together, known as cold drawing, has been the standard for mass production of flexible fibers like plastic and nylon for most of the last century.
Abouraddy and his team have shown that the process may also be applicable to multi-layered materials, a finding that could lead to the manufacturing of a new generation of materials with futuristic attributes.
The University of Central Florida, commonly referred to as UCF, is a metropolitan public research university located in Orlando, Florida, United States. UCF is a member institution of the State University System of Florida, and it is the second-largest university in the United States by enrollment.
The University of Central Florida was authorized by the Florida State Legislature in 1963, and opened in 1968 as Florida Technological University, with the mission of providing personnel to support the growing U.S. space program at the Kennedy Space Center, which is located only 35 miles (56 km) to the east. “Florida Tech” was renamed The University of Central Florida in 1978, as the university’s academic scope expanded beyond its original focus on engineering and technology.
Although initial enrollment in 1968 was only 1,948 students, as of 2013 enrollment consists of 60,181 students from over 140 countries, all 50 states and Washington, D.C. The majority of the student population is located on the university’s 1,415-acre (5.726 km2) main campus approximately 13 miles (21 km) east-northeast of downtown Orlando and 55 miles (89 km) south-southwest of Daytona Beach. The university offers over 200 degree options through twelve colleges and twelve satellite campuses throughout Florida. Since its founding, UCF has awarded almost 250,000 degrees, including 45,000 graduate, specialist and professional degrees, to over 200,000 alumni worldwide.
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- $1 Test Developed at UCF Outperforms PSA Screening for Prostate Cancer – April 13, 2015
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- 255Tbps: World’s fastest network could carry all of the internet’s traffic on a single fiber – October 29, 2014
- New Idea in Energy Storage: Wires that Store and Transmit Energy – June 3, 2014
- ‘Dressed’ Laser Aimed at Clouds May be Key to Inducing Rain, Lightning | control rain and lightning – April 20, 2014
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“Ultimately, you could artificially control the rain and lightning over a large expanse with such ideas.”
The adage “Everyone complains about the weather but nobody does anything about it,” may one day be obsolete if researchers at the University of Central Florida’s College of Optics & Photonics and the University of Arizona further develop a new technique to aim a high-energy laser beam into clouds to make it rain or trigger lightning.
The solution? Surround the beam with a second beam to act as an energy reservoir, sustaining the central beam to greater distances than previously possible. The secondary “dress” beam refuels and helps prevent the dissipation of the high-intensity primary beam, which on its own would break down quickly. A report on the project, “Externally refueled optical filaments,” was recently published in Nature Photonics.
Water condensation and lightning activity in clouds are linked to large amounts of static charged particles. Stimulating those particles with the right kind of laser holds the key to possibly one day summoning a shower when and where it is needed.
Lasers can already travel great distances but “when a laser beam becomes intense enough, it behaves differently than usual – it collapses inward on itself,” said Matthew Mills, a graduate student in the Center for Research and Education in Optics and Lasers (CREOL). “The collapse becomes so intense that electrons in the air’s oxygen and nitrogen are ripped off creating plasma – basically a soup of electrons.”
At that point, the plasma immediately tries to spread the beam back out, causing a struggle between the spreading and collapsing of an ultra-short laser pulse. This struggle is called filamentation, and creates a filament or “light string” that only propagates for a while until the properties of air make the beam disperse.
“Because a filament creates excited electrons in its wake as it moves, it artificially seeds the conditions necessary for rain and lightning to occur,” Mills said. Other researchers have caused “electrical events” in clouds, but not lightning strikes.
But how do you get close enough to direct the beam into the cloud without being blasted to smithereens by lightning?
“What would be nice is to have a sneaky way which allows us to produce an arbitrary long ‘filament extension cable.’ It turns out that if you wrap a large, low intensity, doughnut-like ‘dress’ beam around the filament and slowly move it inward, you can provide this arbitrary extension,” Mills said. “Since we have control over the length of a filament with our method, one could seed the conditions needed for a rainstorm from afar. Ultimately, you could artificially control the rain and lightning over a large expanse with such ideas.”
So far, Mills and fellow graduate student Ali Miri have been able to extend the pulse from 10 inches to about 7 feet. And they’re working to extend the filament even farther.
“This work could ultimately lead to ultra-long optically induced filaments or plasma channels that are otherwise impossible to establish under normal conditions,” said professor Demetrios Christodoulides, who is working with the graduate students on the project.
“In principle such dressed filaments could propagate for more than 50 meters or so, thus enabling a number of applications. This family of optical filaments may one day be used to selectively guide microwave signals along very long plasma channels, perhaps for hundreds of meters.”
Other possible uses of this technique could be used in long-distance sensors and spectrometers to identify chemical makeup. Development of the technology was supported by a $7.5 million grant from the Department of Defense.