Faster-Charging, Safer Batteries

Estimated reading time: 6 minutes

Priyanka Ketkar, a doctoral student in chemical and biomolecular engineering, wants to make a difference in the world through research. Ketkar described the Epps research group as a good fit, where she is exercising her mental muscle on consequential problems related to energy storage.

In laboratory experiments, Ketkar and others in the Epps group have shown that introducing a tapered region between polymer electrolyte chains actually increased the overall ionic conductivity over a range of temperatures. At room temperature, for example, the tapered materials are twice as conductive as their non-tapered counterparts. But that is not all. The taper improves the material’s ability to be processed, too.

“Previous methods for increasing conductivity have either made the polymer harder to process or used greater amounts of chemical solvent, which makes the material more flammable and less environmentally friendly,” Ketkar said. “That is why I am really excited about this new approach.” 

The designer polymers are useful for lithium-ion batteries, but also applicable to other rechargeable systems, such as sodium-ion and potassium-ion batteries, Epps said. Other applications include using tapered polymers to make materials that can be produced at lower temperatures or with less solvent for applications such as tires, rubber bands and adhesives.

Future Applications Include Flexible Batteries

As technology rockets forward, Epps expects the next five to 10 years will usher in a plethora of devices that can flex and roll, such as cell phones and computers.

“The only way this works is if all of the components are flexible, including the battery and power units, not just the case, screen or buttons,” Epps said. “This aspect is where block polymers become really ideal because — like a rubber band that remembers its shape despite stretching, bending and other manipulation — with polymers, you can make the internal components more impact resistant and shock absorbing, which will improve the phone’s lifespan.”

There may be other applications for designer polymers, too.

“What if there was a sensor inside the football that was designed to alert officials when a player crosses a specific yardage, say for a first down,” Epps said. “You would not need to rely on an official’s on-field view of the play or instant replay.”

But, footballs get thrown around and the players who hold them are often hit.

“You would need something that will not break or leak, so using a polymer that has the material properties of say, a rubber band, that also can conduct ions like a battery would be a perfect solution,” Epps said. “This avenue is one direction in which you could imagine these materials blossoming.”

Epps was recently appointed a fellow of the Royal Society of Chemistry, based in the United Kingdom. To receive this honor, scientists must have made an impact in the chemical sciences.

Funding for this work is from the U.S. Department of Energy’s Basic Energy Sciences program, the National Science Foundation’s Division of Materials Research, and Samsung. Epps’ work includes a collaboration with the National Institute of Standards and Technology, UD’s Center for Neutron Science, and Lisa Hall, an associate professor of chemical and biomolecular engineering at Ohio State University.

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