Graduate Student Researchers Design Promising New Energy Storage Device
While the sun and wind provide great alternative energies, the supplies can be highly variable when the sun isn’t shining or the wind isn’t blowing, and there is no way to efficiently store the energy. Also consider the Achilles’ heel of electric vehicles: it can take hours to recharge them.
To solve these problems, researchers from the Cockrell School of Engineering and the College of Natural Sciences at The University of Texas at Austin are developing energy storage devices called pseudocapacitors that can charge and discharge much faster than commercial batteries.
The researchers hope that the technology will one day advance enough to charge electric cars in minutes instead of hours and to provide long-term energy storage for power grids.
The student-led study — spearheaded by materials science and engineering graduate student William Hardin and analytical chemistry graduate student Tyler Mefford — reports a new energy storage mechanism for pseudocapacitor electrodes that promises to boost the energy density and power density of pseduocapacitor devices. Professors Keith P. Johnston of the McKetta Department of Chemical Engineering and Keith Stevenson of the Department of Chemistry oversaw the project, which was published in July in the journal Nature Materials. These two professors have worked together with more than a dozen students over the last eight years on materials chemistry and electrochemistry.
Conventional pseudocapacitors rely on expensive, scarce metals and use cations (positive ions) to store energy. The team’s device is both the first to utilize oxygen anions (negatively charged ions) instead of cations to store energy and the first to be based on a type of material called perovskite that is found abundantly in Earth’s mantle.
“Not only are we working with oxygen, which is abundant and safe, but we are working with perovskite, and the performance of the material is quite high,” Hardin said.
The concept for the ion-based pseudocapacitor was built upon Hardin’s earlier work with then-graduate student Daniel Slanac and both professors.
Hardin and Slanac were inspired by the work of Cockrell School professor John Goodenough, a legend in energy storage research whose work led to the invention of the lithium-ion battery. Goodenough has studied the properties of perovskite for decades.
“Goodenough and others’ research established a precedent for oxygen mobility in perovskite, and helped us correctly identify the mechanism and method of energy storage in our perovskite system using oxygen,” Hardin said.
Perovskites have a unique structure containing vacant sites where oxygen anions can be stored, making these advancements a possibility.
“One main advantage of oxygen ions is that they can allow you to theoretically store double the energy, providing two electrons per ion stored,” Mefford said. “It’s also a proof of concept that this kind of charge storage strategy can work.”
The research team is continuing to explore and improve perovskites’ ability to generate and store electricity using oxygen.
While the technology is at least five to 10 years away from commercialization, it has the potential to meet a huge need for quick and reliable energy charging and storage.
“People want to use electric vehicles and we want to go to a smart grid, but energy storage is one of biggest things holding us back,” Mefford said.Tags: batteries, chemical engineering, Energy storage, energy storage devices, Keith P. Johnston, research, UT Austin, Will Hardin