Researchers from the University of Wollongong say they have achieved a breakthrough in battery technology that could see sodium-sulfur batteries emerge as an attractive technology for large-scale energy storage.
In new research published in the journal Nature Communications, the University of Wollongong researchers have produced nanomaterials to act as a key component of sodium-sulfur batteries, that offer higher energy densities and increased charge-discharge cycle-life at a cost the university predicts could become competitive with lithium-ion batteries.
While sodium-sulfur batteries offer the potential very high energy storage density and very high conversion efficiencies, producing a working example at room temperatures has proven difficult due to instabilities in the chemical reactions within the batteries.
“This indicates that sodium-sulfur batteries with this sulfur host could potentially offer a longer cycle life and high performance in fast charging and discharging,” University of Wollongong PhD candidate, who contributed to the project, Zichao Yan said.
Most working examples of sodium-sulfur batteries require them to operate at temperatures of up to 350 degrees. But by deploying nano-materials, nickel sulfide nanocrystals, as a cathode within the sodium-sulfur batteries, the researchers were able to achieve improved performance from the batteries at room temperatures,
Researchers believe they have achieved a crucial step towards making the sodium based batteries more stable at room temperatures, that would support the technology being used on a larger scale as an energy storage solution.
The research team at the University of Wollongong experimented with a range of different materials to act as the “cathode” within the sodium-sulfur batteries, discovering that nickel sulfide nanocrystals provided the ideal solution for maintaining a stable battery reaction.
According to the researchers, the use of nickel sulfide nanocrystals also lends itself to large-scale commercial production.
While the achievement is a critical step towards the deployment of sodium-sulfur batteries, the University of Wollongong was cautious to warn that further research is required to improve the performance of the technologies at room-temperatures before the technology would be commercially ready.
“For now, the actual energy densities of sodium-sulfur batteries are a far cry from the theoretical values. Unfortunately, the actual energy densities of room-temperature sodium-sulfide batteries are a far cry from the theoretical values. The research on this system is still in its infancy” chief investigator Dr Yunxiao Wang said
“The room-temperature sodium-sulfide batteries have attracted attentions mainly due to the high energy density and low cost. Unlike the traditional low-energy sodium-ion batteries, room-temperature sodium-sulfide batteries can be even smaller and lighter than current lithium ion batteries.”
The University of Wollongong has been working on the development of sodium based batteries since 2016 and the university sees sodium based batteries as providing an effective competitor to established lithium-ion batteries.
The University of Wollongong says that it has focused its research on transferring innovations discovered in the lab to large-scale production.
“All our previous papers, including this one, were focused on how to find an efficient host for lab-scale research. The next step for our group is to bring sodium-sulfur batteries from lab-scale to industry-scale, and make a real application for this battery system,” chief investigator Prof Shulei Chou said.
The university has previously been involved in the demonstration of sodium-ion batteries, that effectively use sodium as an alternative to lithium in the production of batteries with similar performance.
As part of a study funded by the Australian Renewable Energy Agency, the University of Wollongong deployed its sodium-ion technology across multiple sites controlled by Sydney Water.
The trade-off with sodium is weight and size. While sodium batteries can achieve similar performance to that of lithium-ion batteries potentially lower costs, size of sodium batteries will always remain larger.
The market for sodium batteries will likely be in large-scale energy storage, where size and weight is less of a constraint, while lithium-ion batteries will retain an advantage in electric vehicles and consumer electronics.