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. Professor Fernando Uribe-Romo 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. Credit: Nick Russett
2 University of Central Florida scientists 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 Demetrius A. Vazquez-Molina took COF-5, a nano sponge-like, non-flammable humanmade 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 are significant because a liquid is necessary for some electronics and other energy uses. But using current liquid materials sometimes is problematic. Eg lithium-ion batteries, used in 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. “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.
Covalent organic frameworks (COFs) usually crystallize as insoluble powders, and their processing for suitable devices is thought to be limited. We demonstrate that COFs can be mechanically pressed into shaped objects having anisotropic ordering with preferred orientation between hk0 and 00l crystallographic planes. Five COFs with different functionality and symmetry exhibited similar crystallographic behavior and remarkable stability, indicating the generality of this processing. Pellets prepared from bulk COF powders impregnated with LiClO4 displayed room temperature conductivity up to 0.26 mS cm–1 and high electrochemical stability. This outcome portends use of COFs as solid-state electrolytes in batteries.
“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.” After finishing his bachelor’s degree at Instituto Tecnológico y de Estudios Superiores de Monterrey in Mexico, Uribe-Romo earned a Ph.D. at UCLA. He was a postdoctoral associate at Cornell University before joining UCF as an assistant professor in 2013.
The findings were pursued by a team lead by Uribe-Romo in collaboration with scientists at UCLA’s Department of Chemistry and Biochemistry. They wish to see COF-5 is indeed the material that could revolutionize battery and mobile device industries.
http://today.ucf.edu/ucf-team-tricks-solid-acting-liquid/
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