“It’s really over the past five to ten years that lithium-ion technology has really taken hold as the leading paradigm for battery design,” said Michael Thackeray, who leads Argonne’s Center for Electrical Energy Storage (CEES). “Many people saw the potential of lithium, but few anticipated that it would provide such a versatile technology for so many devices. Lithium-ion batteries are just so much more flexible than the older battery systems we’ve had for decades, like lead-acid and nickel-cadmium batteries. We’ve just begun to explore the different ways in which we might be able to improve the effectiveness of lithium battery technology.”
CEES is one of three Argonne-led Energy Frontier Research Centers (EFRCs) that were established in 2009 thanks to a special block grant from the U.S. Department of Energy that sought to establish five-year interdisciplinary programs focused around discrete scientific challenges. As part of the overall effort to transform the energy economy, Argonne also leads EFRCs to improve catalysts for biofuel production and develop new photovoltaic devices that can better capture solar energy.
At CEES, Thackeray and his colleagues at Argonne, Northwestern University and the University of Illinois at Urbana-Champaign strive to obtain an understanding of lithium battery systems; the effort draws on the expertise at the three institutions, not only in materials synthesis and design but also theoretical chemistry and physics, computation and materials characterization.
“The program we’ve established focuses predominantly on gathering a comprehensive understanding of the interfaces within a battery as well as electrochemical phenomena that occur at these interfaces,” Thackeray said. “The unifying mission is to provide scientific knowledge that will contribute to advancing lithium battery technologies; to do so, we have to bring all of our resources to bear on these problems.”
Batteries that will power new generations of plug-in hybrid cars will have to overcome a limitation that so far has prevented them from attracting widespread consumer appeal, according to Thackeray. “Science hasn’t yet come up with the answers that would allow us to create a battery with sufficient electrical energy density to allow drivers to get the same range as they can with a conventional gasoline engine,” he said. “It’s up to us to develop materials and chemistries that will lead to a battery that will truly begin to replace petroleum as the principal source of fuel.”
One way to increase the amount of energy in a lithium-ion battery is to use electrode materials that provide higher voltages. High voltage batteries, however, bring additional risks because they are more likely to degrade and fail. Reaping the payoff of increased voltage and energy density, while making absolutely sure the battery can be operated safely for long periods of time, represents one of the primary challenges of energy storage research, Thackeray said.
In a recent development at the University of Illinois, CEES investigators have initiated studies of self-healing materials, in which electrical conductivity within an electrode can be autonomously restored if contact is lost. This new approach has helped to change conventional expectations of lithium battery performance, according to Thackeray.
While an easily affordable all-electric, zero-emissions vehicle may take a number of years to develop, Thackeray is confident that the research produced by the EFRCs, taken together with other national energy storage programs across the US, will expedite the process of bringing the greenest cars to market. “Energy storage science isn’t necessarily the flashiest science,” he said, “but if you want to look at the entire pipeline of where electric cars will come from, we’re hopefully at a point where we can make an impact.”