Oxygen vacancies unlock fast lithium-ion transport in battery material

Lithium titanate, a traditional battery material known for its poor lithium ion conductivity when pristine, undergoes a significant transformation into a superior ion conductor through the deliberate introduction of oxygen vacancies. Researchers from the Institute of Chemistry and Technology of Materials at TU Graz, Bernhard Gadermaier and Martin Wilkening, achieved this by heating pure, non-lithiated Li4Ti5O12 to 300 degrees Celsius in an oxygen-poor atmosphere.

This process removes individual oxygen atoms from the crystal lattice, activating a previously blocked migration pathway for lithium ions. The resulting oxygen vacancies, which are already present in the LTO structure, have a direct impact on the mobility of lithium cations, converting the material from a poor to an enhanced ionic conductor.

Experimental verification of this phenomenon was conducted using conductivity spectroscopy and nuclear magnetic resonance (NMR) spectroscopy, with NMR measurements providing direct evidence of the newly activated atomic-scale diffusion pathway. This research, published in Science Advances, underscores the profound influence that atomic-scale defect structures and thermal history can have on the macroscopic properties of a material.

It also highlights how fundamental research, driven by scientific curiosity, can lead to the discovery of new material functions, opening up potential applications in iontronic, memristive, and neuromorphic devices for micro- and nanoelectronics.