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Physics-defying material brings dead EV batteries back to life

Defying conventional principles of thermodynamics, this material is breaking new ground in both applied and theoretical science.

Scientists have discovered a revolutionary material that expands when squeezed, contracts when heated, and could not only revive aging EV batteries but also reshape the fundamental understanding of matter itself.

In a discovery that appears to challenge the laws of thermodynamics, researchers from the Pritzker School of Molecular Engineering (PME) at the University of Chicago and the University of California, San Diego have observed negative thermal expansion in metastable oxygen-redox-active materials.

Surprisingly, while the material behaves normally under heat, pressure, and electricity in its steady state, the team found that in its newly discovered metastable state, its reactions are completely reversed.

“When you heat these materials, there is no change in volume,” said Dr. Shirley Meng, a professor of molecular engineering at the University of Chicago and one of the study’s authors. “When they heat up, these materials contract instead of expanding.”

Meng believes that the properties of the materials could be finely tuned through redox chemistry, opening the door to future technological applications. “That could lead to some very exciting applications,” she added.

Potential applications...Meng says the most exciting aspect of the discovery is not just its potential to unlock new technologies, but also the fundamental leap it represents in pure science.

“This changes our understanding of fundamental science,” Meng said, noting that the team’s work follows the University of Chicago model of pursuing knowledge for its own sake.

But Bao Qiu, a visiting scholar at the University of California, San Diego, from China’s Ningbo Institute of Materials Technology and Engineering (NIMTE) and co-first author of the study, is already turning his attention to real-world applications.

“One of the goals is to transition these materials from the research sphere to industry, namely to develop new batteries with higher specific energy,” Qiu said in a press release.

By carefully tuning the way these materials respond to heat and energy, the researchers believe they could develop substances with zero thermal expansion, a development that could have major implications for construction and beyond.

“Zero thermal expansion materials are in the realm of dreams, I would say,” said Dr. Minghao Zheng, an associate professor and co-corresponding author of the study. “Take any building as an example. You don’t want the materials that make up the different components to change volume so frequently.”

But the heat was just the beginning. The team also continued to investigate how the material responds to mechanical energy, subjecting it to extreme pressure in the gigapascal range—a range typically associated with plate tectonics. To their surprise, they observed what they describe as “negative compressibility.”

“Negative compressibility is the same as negative thermal expansion,” Zhang said. “If you compress a particle of a material in all directions, you would naturally think it would shrink. But this material expands.”

Bringing old electric vehicles back to life...According to Zhang, a material that can withstand heat or pressure is leading to bold ideas like creating structural batteries, where the walls of an electric plane act as batteries, making the plane lighter and more efficient. These new materials could protect battery components from extreme changes in temperature and pressure at high altitudes, opening up new possibilities for advanced aerospace technology.

Meanwhile, the material’s response to voltage is similarly reversible, reflecting its unusual behavior under heat and pressure. “This is important not only as a scientific discovery, but also very applicable when it comes to battery research,” Zhang noted. “When we apply voltage, we restore the material to its original state. We restore the battery.”

To explain metastability, Zhang describes a simple example of a ball resting on a hill. At the top, it is unstable and rolls, while at the bottom, it is stable and stays in place. A metastable state is like a ball lying in a small dip near the top, because it appears stable, but a little pressure can move it. One of the most famous metastable materials is diamond, a metastable form of graphite.

“To return a material from a metastable state to a stable state, you don’t always have to use heat energy,” Zhang said. “You can use any kind of energy to restore the system.”

This feature, according to the scientist, opens the door to refurbishing old EV batteries. Over time, an electric vehicle that once had a range of over 600 kilometers (370 miles), loses its range, which can drop below 500 or even 400 kilometers (250 miles). However, by using electrochemical energy to restore the battery materials to their stable states, the researchers believe it may be possible to restore the original range.

“You don’t have to send the battery back to the manufacturer or the retailer. Just do this voltage activation,” Zhang concluded. “In effect, your car will be a new car, and your battery will be a new battery.”

The team hopes to continue using redox chemistry to study the materials in detail and identify the key mechanisms at play, pushing the boundaries of a new field in fundamental research.

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