The battery tech that could get us to net zero

Sodium-sulphur (Na-S) batteries aren’t new. In fact, they’ve existed for more than half a century. But they’ve long been considered an inferior alternative, not least because they’ve been limited by low energy capacity and short life cycles. Until now. 

To find out how this development came about, and what exactly it could mean in real-world terms, we caught up with  the man who led the research, Dr Shenlong Zhao from Sydney University’s School of Chemical and Biomolecular Engineering.

Their findings were published in Advanced Materials.

Interesting Engineering: What prompted this research in the first place? 

Dr Zhao: The 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.

It’s 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.

Why does this matter?

Well, according to the Clean Energy Council, in 2021 32.5 percent 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. And that’s just Australia – obviously this is a global issue 

How can this solution help?

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.

And how does it work?

[Using] a simple pyrolysis process and carbon-based electrodes to improve the reactivity of sulphur and the reversibility of reactions between sulphur and sodium, this battery exhibits super-high capacity and ultra-long life at room temperature.

What impact do you hope this will have on a wider scale?

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 decarbonize – the better chances we have of capping warming.

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

Are there any other advantages to these batteries, beyond their potential environmental benefits and their price?

Yes. We have all heard horror stories of lithium-ion batteries in transport settings, usually down to issues around cracked casing caused by exposure to stressful environments, such as extreme temperature changes.

Our research proves that it’s possible to produce more robust, solid-state lithium-ion batteries, which should provide a promising approach for high-energy and safe future models to be used in real-life examples such as electric vehicles.

Furthermore, Na-S cells are also less toxic and more energy intense, making them easier to recycle and more economical to produce when compared to lithium-ion batteries, which are widely used in electronic devices and for energy storage.

During the battery’s development, we kept in mind the various use-case scenarios, with priority given to providing a viable alternative for large renewable energy storage systems, such as electrical grids, while significantly reducing operational costs.

This technology has potential to guarantee greater energy security more broadly and allow more countries to join the shift towards decarbonization.

What’s the next step for this development?

We fabricated and tested the technology with lab-scale batteries at the University's chemical engineering facility. Now, the next step involves scaling the technology used in the Ah-level pouch cells (which is a type of battery cell) to commercialize it on a large scale.

What do you think will stop this from becoming commercially available, if anything? 

Although it reduces costs in the long term, there are several financial barriers to entry that we need to overcome.

Are you conducting any further research in this field? 

Yes. At our Ion Beam Centre, we injected Xenon ions into a ceramic oxide material to create a solid-state electrolyte. Our team found that their method created a battery electrolyte that showed a 30-times improvement in lifespan over a battery that had not been injected.

The full paper for that, which is led by myself and Dr Nianhua Peng, is published in Small.

Co-author of that study, Dr Nianhua Peng, said of those findings: “We are living in a world that is far more aware of the damage humans are causing to the environment. We hope that our battery and approach will help boost the scientific development of high-energy batteries to eventually move us into a more sustainable future.”

This story first appeared in our subscriber-only weekly Blueprint newsletter. Receive exclusive interviews and analyses like this, direct to your inbox every Sunday, by subscribing to IE+.