A spoonful of sugar for long-lasting lithium–sulfur batteries

Australian researchers say they have managed to stabilise lithium–sulfur battery technology, long touted as the basis for the next generation of batteries, by simply using a glucose-based additive on the positive electrode — a spoonful of sugar, if you will.

In theory, lithium–sulfur batteries could store 2–5 times more energy than lithium-ion batteries of the same weight. The problem was that in use the electrodes deteriorated rapidly, and the batteries broke down. There were two reasons for this: the positive sulfur electrode suffered from substantial expansion and contraction, weakening it and making it inaccessible to lithium, and the negative lithium electrode became contaminated by sulfur compounds.

Last year, researchers from the Monash Energy Institute demonstrated that they could open the structure of the sulfur electrode to accommodate expansion and make it more accessible to lithium. More recently, they were inspired by a 1988 geochemistry report that describes how sugar-based substances resist degradations in geological sediments by forming strong bonds with sulfides.

By incorporating sugar into the web-like architecture of the electrode, the team successfully stabilised the sulfur, preventing it from moving and blanketing the lithium electrode. Test-cell prototypes have been shown to have a charge–discharge life of at least 1000 cycles, while still holding far more capacity than equivalent lithium-ion batteries, as reported in the journal Nature Communications.

“Each charge lasts longer, extending the battery’s life,” said first author and PhD student Yingyi Huang. “And manufacturing the batteries doesn’t require exotic, toxic and expensive materials.”

“In less than a decade, this technology could lead to vehicles including electric buses and trucks that can travel from Melbourne to Sydney without recharging,” added lead author Professor Mainak Majumder, Associate Director of the Monash Energy Institute. “It could also enable innovation in delivery and agricultural drones, where light weight is paramount.”

Dr Mahdokht Shaibani, second author and Monash researcher, noted, “While many of the challenges on the cathode side of the battery have been solved by our team, there is still need for further innovation into the protection of the lithium metal anode to enable large-scale uptake of this promising technology — innovations that may be right around the corner.”

The process was developed by the Monash team with significant contribution from Dr Matthew Hill’s research group at CSIRO Manufacturing. They were also supported by the Australian Research Council, the Department of Industry, Innovation and Science, and Cleanfuture Energy Australia, a subsidiary of Enserv Group in Thailand.

Enserv Australia hopes to develop and manufacture the Monash team’s lithium–sulfur batteries in Australia, with Managing Director Mark Gustowski saying the company would use the technology to enter the growing market for electric vehicles and electronic devices.

“We plan to make the first lithium–sulfur batteries in Australia using Australian lithium within about five years,” he said.

Image caption: The Monash Energy Institute team includes Mahdokht Shaibani, Mainak Majumder, Matthew Hill and Yingyi Huang.