An international team of researchers are hoping that a new, low-cost battery which holds four times the energy capacity of lithium-ion batteries and is far cheaper to produce will significantly reduce the cost of transitioning to a decarbonised economy.

Led by Dr Shenlong Zhao from the University's School of Chemical and Biomolecular Engineering, the battery has been made using sodium-sulphur – a type of molten salt that can be processed from sea water – costing much less to produce than lithium-ion.

Although sodium-sulphur (Na-S) batteries have existed for more than half a century, they have been an inferior alternative and their widespread use has been limited by low energy capacity and short life cycles.

Simple pyrolysis process

Using a simple pyrolysis process and carbon-based electrodes to improve the reactivity of sulphur and the reversibility of reactions between sulphur and sodium, the researchers' battery has shaken off its formerly sluggish reputation, exhibiting super-high capacity and ultra-long life at room temperature.

The researchers say the Na-S battery is also a more energy dense and less toxic alternative to lithium-ion batteries, which, while used extensively in electronic devices and for energy storage, are expensive to manufacture and recycle.

Dr Zhao's Na-S battery has been specifically designed to provide a high-performing solution for large renewable energy storage systems, such as electrical grids, while significantly reducing operational costs.

According to the Clean Energy Council, in 2021 32.5% of Australia's electricity came from clean energy sources and the industry is accelerating. Household energy storage is also growing. According to a recent report a record 33,000 batteries were installed in 2021.

"Our sodium battery has the potential to dramatically reduce costs while providing four times as much storage capacity. This is a significant breakthrough for renewable energy development which, although it reduces costs in the long term, has had several financial barriers to entry," said lead researcher Dr Zhao.

High-quality storage solutions

"When the sun isn't shining and the breeze isn't blowing, we need high-quality storage solutions that don't cost the Earth and are easily accessible on a local or regional level.

"We hope that by providing a technology that reduces costs we can sooner reach a clean energy horizon. It probably goes without saying but the faster we can decarbonise – the better chances we have of capping warming.

"Storage solutions that are manufactured using plentiful resources like sodium – which can be processed from sea water – also have the potential to guarantee greater energy security more broadly and allow more countries to join the shift towards decarbonisation."

The lab-scale batteries (cion batteries) have been successfully fabricated and tested in the University of Sydney's chemical engineering facility. The researchers now plan to improve and commercialise the recently fabricated Ah-level pouch cells.