Zero thermal expansion materials rejuvenate aging batteries

A team of scientists have developed zero thermal expansion (ZTE) materials. This innovation has achieved nearly 100% voltage recovery in aging lithium-ion batteries (LIBs). Their study is published in Nature.

LIBs have become increasingly essential in the markets for electric vehicles and aircraft. Lithium-rich layered oxide cathode materials can deliver record capacities exceeding 300 mAh/g, thanks to revolutionary oxygen-redox (OR) chemistry.

However, they are plagued by operational instability. The OR activity that enhances energy density by 30% also triggers asymmetric lattice distortion and voltage decay, which accelerates battery aging.

Thermal expansion is a common phenomenon in nature. It often leads to structural disorder or loss of precision, ultimately compromising material performance.

The researchers led by Prof. Liu Zhaoping at the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences, in collaboration with researchers from the University of Chicago and other institutions, discovered negative thermal expansion (NTE) behavior in lithium-rich layered oxide cathode materials, which contract when heated within the temperature range of 150–250°C.

This unusual behavior, contrary to conventional thermodynamic expectations, can be attributed to thermally driven disorder-order transitions.

Treating structural disorder as a tunable parameter rather than a defect, the researchers revealed a correlation between OR activity and NTE coefficients.

“By tuning reversible OR activity, the thermal expansion coefficient can be precisely switched among positive, zero, and negative states,” explained Qiu Bao, a lead author of the study.

The team established a robust predictive framework, enabling the world’s first ZTE cathode through precise OR tuning. These ZTE materials effectively counteract thermal expansion, enhancing structural stability and durability.

When subjected to 4.0 V voltage pulses, the lattice structure was reconstructed, achieving nearly 100% voltage recovery. This finding suggests that smart charging systems could restore materials from disordered states to ordered states in situ using electrochemical methods, potentially doubling battery lifespan.

Beyond rejuvenating aging batteries, making old electric vehicles like new, this advancement opens new frontiers in ZTE material engineering. The study also sheds light on the self-healing function design of high-performance devices.