Marco Buongiorno-Nardelli, professor of physics, and his colleagues at North Carolina State University have solved the mystery of how a specially designed polymer is able to store and release large amounts of energy -- a discovery that could result in more powerful and more efficient electric cars.
One of the barriers to widespread adoption of electric vehicles is energy storage. Current technologies struggle to give electric vehicles the get-up-and-go necessary to accelerate quickly from a standstill. Researchers are looking to capacitors using engineering polymers to solve this problem.
Buongiorno-Nardelli says capacitors are like batteries in that they store and release energy. However, capacitors use separated electrical charges, rather than chemical reactions, to store energy. The charged particles enable energy to be stored and released very quickly. Imagine an electric vehicle that can accelerate from zero to 60 mph at the same rate as a gasoline-powered sports car, he says.
"There are no batteries that can power that type of acceleration because they release their energy too slowly," he adds "Capacitors, however, could be up to the job -- if they contain the right materials."
Researchers previously found that capacitors containing the polymer polyvinylidene fluoride, or PVDF, in combination with another polymer called CTFE, were able to store up to seven times more energy than those currently in use. However, researchers did not understand the mechanism that made this increased storage possible. Buongiorno-Nardelli and Jerzy Bernholc, a researcher at North Carolina State, designed a study to analyze the movement of the atoms in PVDF and identify this mechanism.
Vivek Ranjan, a post-doctoral researcher at North Carolina State, conducted the computer simulations that revealed the atoms in the PVDF mixture were transitioning from a non-polar to a polar state in a simultaneous and synchronized movement. This transition required little electrical charge, allowing it to store and release greater amounts of energy.
The findings from this study, which was funded by the U.S. Department of Defense's Office of Naval Research, were published in Physical Review Letters. Buongiorno-Nardelli says the team will now turn their focus to identifying a polymer that is even more efficient at storing and releasing energy than PVDF.
Buongiorno-Nardelli joined the UNT faculty in January 2012. Prior to arriving at UNT, he was a professor at North Carolina State. He currently has a joint appointment in the Department of Physics and Department of Chemistry. He also is a member of UNT's Materials Modeling Research Cluster, one of 15 multidisciplinary research clusters addressing complex scientific, technological, environmental and societal issues through collaboration and innovation.
Alyssa Yancey with UNT News Service can be reached at Alyssa.Yancey@unt.edu.