Oxygen vacancies speed lithium transport in lab battery material

At 300°C, inside a low-oxygen furnace, researchers at Graz University of Technology in Austria removed individual oxygen atoms from lithium titanate. The missing atoms left vacancies in the crystal lattice—and turned an otherwise sluggish lithium-ion pathway into a faster route through the material.

Lithium titanate, or LTO, is an anode material for lithium-ion batteries. It is already valued for safety, durability, ultra-fast charging and operation at low temperatures. But pristine LTO, before charging begins, is a poor ionic conductor. It usually becomes more conductive only after extra lithium ions and electrons enter its structure.

Chemists Bernhard Gadermaier and Martin Wilkening took another route: they built the defects into the uncharged material from the start. The oxygen vacancies do not replace LTO’s basic formula. Instead, they activate a diffusion pathway that is already present in the crystal architecture, giving lithium cations more room to move while preserving LTO’s “zero-strain” behavior—its lattice undergoes almost no volume expansion or contraction during lithium insertion and extraction.

The team checked the effect at two scales. Conductivity spectroscopy measured the overall flow through the material, while nuclear magnetic resonance, or NMR, spectroscopy followed individual lithium cations. Together, the measurements showed that the missing oxygen atoms triggered the newly active diffusion route. The study was published in Science Advances.

So what changes in practice? The result gives battery researchers a way to tune ion transport through heat treatment and atomic-scale defects rather than relying only on chemical composition or charging. It could also inform iontronic, memristive and neuromorphic systems.