Researchers at the University of Surrey have created a library of 28 sodium-ion cathode materials that they say could form the basis for future artificial intelligence (AI) models to help design batteries that charge faster, last longer and store more energy. The study, published in the Journal of Materials Chemistry A, examined how changing the chemical makeup of sodium manganese oxide affects its performance as a cathode.
Why sodium-ion batteries are being developed
Sodium-ion batteries are being developed as an alternative to conventional lithium-ion batteries, because sodium is much more abundant and widely available. However, according to the university, improving how much energy they can hold and how well they perform over repeated charging is a major barrier to their wider use.
The cathode is central to that challenge, as it helps determine how much energy a battery can store and how well it performs. Climate Global News has previously reported on research into scandium doping of sodium manganese oxide cathodes, another approach to extending battery life.
Dr Daniel Commandeur, Lecturer at the School of Chemistry and Chemical Engineering and corresponding author of the study, said: “We rely heavily on lithium-ion batteries, but lithium resources are relatively scarce and unevenly distributed around the world. Sodium is far more abundant, making sodium-ion batteries an important technology to develop.”
Testing 28 sodium-ion cathode materials
The team substituted some of the manganese in sodium manganese oxide with varying amounts of iron, titanium and vanadium, producing 28 different compositions. Each composition was then tested in sodium-ion batteries and its performance compared with the others.
Iron was linked to higher energy-storage capacity, while vanadium improved stability over repeated charging and discharging. Small amounts of titanium improved performance at higher rates, and some titanium-containing compositions retained more than 90 per cent of their capacity after 100 cycles.
Eden Marks, PhD Student in Space Engineering and co-lead author of the study, said: “What stood out most was how relatively small changes in composition could shift the balance between how much energy a material can store, how it performs at higher rates and how well it lasts. Mapping those relationships gives us a much clearer picture of where to look next.”
Building datasets for machine learning
The researchers developed an automated approach to analyse the large amounts of data generated by the experiments, and used the resulting dataset to train a machine-learning model. The university said the current library is too small for reliable predictions.
Expanding it, however, could eventually allow AI to identify new battery compositions before they are made and tested in the laboratory. Dr Commandeur said: “The challenge is finding materials that deliver the performance we need. This work is a first step towards building the larger datasets needed for machine learning to guide that search – helping us identify promising materials faster and accelerate the development of better sodium-ion batteries.”
Tailoring cathodes to different performance needs
According to the university, extending the approach to a much wider range of cathode materials could create the larger, high-quality datasets needed for machine learning to help speed up the discovery of new battery materials.
In future, a larger composition library could help scientists tailor sodium-ion cathodes to different performance needs, whether the priority is storing more energy, charging faster or lasting through more charge cycles. The full paper in the Journal of Materials Chemistry A is available online. Climate Global News has also covered earlier sodium-ion battery research at the University of Surrey.
Frequently asked questions
What did the University of Surrey researchers create?
They created a library of 28 different sodium manganese oxide cathode compositions, substituting some of the manganese with varying amounts of iron, titanium and vanadium, and tested each in sodium-ion batteries.
How did iron, titanium and vanadium affect sodium-ion cathode performance?
Iron was linked to higher energy-storage capacity, vanadium improved stability over repeated charging and discharging, and small amounts of titanium improved performance at higher rates. Some titanium-containing compositions retained more than 90 per cent of their capacity after 100 cycles.
How is AI involved in the research?
An automated approach was used to analyse the experimental data, and the resulting dataset was used to train a machine-learning model. The library is currently too small for reliable predictions, but expanding it could eventually allow AI to identify new battery compositions before they are made and tested.
Why are sodium-ion batteries seen as an alternative to lithium-ion batteries?
Sodium is much more abundant and widely available than lithium, which the researchers describe as relatively scarce and unevenly distributed around the world.
Where was the study published?
The study was published in the Journal of Materials Chemistry A.
