ANSTO contributed to a large international collaboration on advanced sodium-ion batteries led by French researchers, which provides a direction for the design of high-performing sodium-ion electrodes. Advanced sodium-ion batteries could be used for large scale energy storage.
A new type of electrode material with a high energy density that is also moisture stable was synthesised and characterised by the researchers using a range of techniques. The material, O3-NaLi1/3Mn 2/3O2, is a sodium-rich layered oxide that did not show voltage fading on cycling.
ANSTO Instrument scientist Dr Max Avdeev, who is also affiliated with the University of Sydney, has expertise in the characterisation of materials for lithium and sodium-ion batteries and other advanced energy materials, was a co-author of the paper published in Nature Materials.
Avdeev collected neutron diffraction data using the Echidna high-resolution diffractometer operated at ANSTO’s Australian Centre for Neutron Scattering to elucidate the distribution of metals in the structure. The data, which reveals the position of the metal atoms during cycling, was combined with other experimental and computational techniques.
“Neutron diffraction is highly sensitive to light elements, such as lithium and sodium, which provides crucial insights into the crystal structure of functional materials,” said Avdeev.
As well as ANSTO/University of Sydney, other collaborating organisations included the College of France, Research Network on Electrochemical Energy Storage (France), Sorbonne University (France), Renault Technocentre (France), Paul Scherrer Institute (France) Skolkovo Institute of Science and Technology (Russia), Advanced Light Source Berkeley National Laboratory (US) University of Orleans (France), University of Pau and Pays (France), the University of Illinois at Chicago (USA), and the University of Montpellier (France).
According to the paper’s abstract, sodium-ion batteries, because of their sustainability attributes, could be an attractive alternative to Li-ion technology for specific applications. However, it remains challenging to design high energy density and moisture stable Na-based positive electrodes.
In the paper, the team report an O3-type NaLi1/3Mn2/3O2 phase showing anionic redox activity, obtained through a ceramic process by carefully adjusting synthesis conditions and stoichiometry. This phase shows a sustained reversible capacity of 190 mAh g−1 that is rooted in cumulative oxygen and manganese redox processes as deduced by combined spectroscopy techniques.
Unlike many other anionic redox layered oxides so far reported, O3-NaLi1/3Mn2/3O2 electrodes do not show discernible voltage fade on cycling. This finding, rationalized by density functional theory, sheds light on the role of inter- versus intralayer 3d cationic migration in ruling voltage fade in anionic redox electrodes.
Another practical asset of this material stems from its moisture stability, hence facilitating its handling and electrode processing. Overall, this work offers future directions towards designing highly performing sodium electrodes for advanced Na-ion batteries.
About ANTSO’s Australian Centre for Neutron Scattering
The Australian Centre for Neutron Scattering is the home of neutron science in Australia and a leading facility in the Asia Oceania region.
It is part of an international network of organisations with neutron sources that deliver world-competitive neutron scattering science from Australian and international users. Research at the Australian Centre for Neutron Scattering been used to determine the internal structure of many types of materials, helping scientists understand why materials have the properties they do, and helping tailor new materials, devices and systems.
