Researchers from the University of Chicago and the University of California San Diego have announced a discovery that could significantly impact material science and electric vehicle (EV) battery technology. The team, including University of Chicago's Pritzker School of Molecular Engineering and visiting researchers, has developed materials that appear to defy traditional thermodynamic laws.
In its stable form, these materials react to heat, pressure, and electricity conventionally. However, when in a "metastable" state, they exhibit unusual reactions. UChicago Professor Shirley Meng explained, "When you heat the materials, there’s no volume change. When heated, the material shrinks instead of expanding." Professor Meng believes that by tuning these properties through redox chemistry, new and exciting applications can emerge.
The researchers detailed their findings in the journal Nature. Co-first author Bao Qiu, a visiting scholar from the Ningbo Institute of Materials Technology & Engineering, expressed potential applications: "One of the goals is bringing these materials from research to industry, possibly developing new batteries with higher specific energy."
Professor Meng highlighted the broader implications of this research, saying, "This changes our understanding of fundamental science." Professor Meng also serves as the faculty director for the Energy Technology Initiative at the Institute for Climate and Sustainable Growth.
Another team member, UChicago Research Associate Professor Minghao Zhang, mentioned possible revolutionary applications in construction using zero-thermal-expansion materials. "Take every single building, for example. You don't want the materials making up different components to change volume that often," Zhang stated.
The team also explored how materials reacted to mechanical energy at high pressures. They observed "negative compressibility," where materials expand when compressed, contrary to ordinary expectations. Zhang suggested that these materials could lead to innovative ideas, such as structural batteries for aircraft.
Old EV batteries could be rejuvenated with these metastable materials. "When we use the voltage, we drive the material back to its pristine state. We recover the battery," Zhang explained. This means EV batteries could regain their original capacity, restoring older electric vehicles to their initial performance levels.
Zhang described this using an analogy of a ball on a hill, illustrating the durable nature of metastable states. "You can use any sort of energy to drive the system back," Zhang said, emphasizing the versatility of restoring materials to a stable state using different energy forms.
The research team is determined to explore further applications of this discovery. Qiu commented on the next steps, "pull out the key points," to explore this new research area further.
The article "Negative-thermal expansion and oxygen-redox electrochemistry" by Qiu et al., was published in Nature on April 16, 2025.