Harnessing Disorder: New Method Renews Aging Battery Cells

The negative and positive thermal expansion behavior of battery cathode materials upon heating. (Image by NIMTE)

A research team led by Professor LIU Zhaoping at the Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences—working in collaboration with the University of Chicago and other partners—has developed zero thermal expansion (ZTE) materials that enable almost full voltage recovery in aging lithium-ion batteries (LIBs). The breakthrough is detailed in a Nature publication.

LIBs are increasingly vital for powering electric vehicles and aircraft. Among them, lithium-rich layered oxide cathodes offer exceptionally high capacities—over 300 mAh/g—thanks to innovative oxygen-redox (OR) chemistry. However, while OR activity boosts energy density by about 30%, it also causes asymmetric lattice distortions and voltage decline, leading to faster battery degradation.

Thermal expansion, a natural process, often disrupts structural integrity and precision, undermining material performance. The NIMTE researchers discovered that lithium-rich layered oxide cathodes exhibit negative thermal expansion (NTE)—shrinking instead of expanding—between 150°C and 250°C. This rare behavior, which defies typical thermodynamic patterns, results from temperature-induced transitions from disordered to ordered atomic structures.

Instead of viewing structural disorder as a flaw, the researchers approached it as a controllable feature, uncovering a link between oxygen-redox (OR) activity and negative thermal expansion (NTE) properties.

“By adjusting reversible OR activity, we can fine-tune the thermal expansion coefficient to be positive, zero, or negative,” explained QIU Bao, one of the study’s lead authors.

The team developed a reliable predictive model, leading to the creation of the world’s first zero thermal expansion (ZTE) cathode through precise OR modulation. These ZTE materials effectively neutralize thermal expansion, significantly improving the battery’s structural integrity and lifespan.

When exposed to 4.0 V voltage pulses, the material’s lattice structure was rebuilt, resulting in nearly full voltage recovery. This breakthrough indicates that advanced charging systems could electrochemically restore battery materials from disordered to ordered states, potentially doubling their usable life.

In addition to reviving aging batteries and extending the life of electric vehicles, this discovery opens exciting possibilities in ZTE material design and offers insights into developing self-repairing features in high-performance technologies.