Ever-abundant sulphur may be answer for more powerful (and cheaper) electric vehicles

There’s a more powerful (and potentially cheaper) alternative to the batteries traditionally used for electric cars, but it’s not a viable option (yet) because it runs too hot with increasing potential for fire and explosion in most environments. A new strategy from Western University may have solved the problem, making lithium-sulphur batteries the answer manufacturers have been looking for to make eco-friendly vehicles more efficient and affordable.

Lithium-sulphur (Li-S) batteries have five times more theoretical gravimetric capacity – the level of performance when a vehicle’s equipment and operations execute continuously at optimum efficiency – than current commercially available lithium-ion (Li-ion) batteries, which would enable them to support far further distances for electric vehicles with far fewer recharges. The problem is that the carbonate-based electrolytes used in conventional Li-ion batteries to regulate temperatures and performance are generally not compatible in Li-S batteries.

Xueliang (Andy) Sun, Western’s Canada Research Chair in Nanostructured Materials for Energy Storage and Conversion, and his collaborators from Western Engineering, Western’s Department of Chemistry and Canadian Light Source have developed a new solid-phase conversion mechanism between sulphur and lithium sulphide which would enable universal application of sulphur cathodes in carbonate-based electrolytes, meaning sulphur – which is highly abundant in Canada and as a result, relatively inexpensive – could be used in lithium batteries as opposed to cobalt, which is a rarer and far more expensive chemical element than sulphur.

“Carbonate-based electrolytes have been applied in commercial Li-ion batteries for 30 years and can impart advantages in Li-S batteries due to their safe and stable properties as well as wide operation temperature window,” explains Xia Li, a Mitacs postdoctoral fellow at Western’s Advanced Materials for Clean Energy Group. “We wanted to find a way to effectively use these same carbonate electrolytes for common high-energy sulphur cathodes and we’ve found it.”

Sun and Li worked closely with renowned Western chemist T.K. Sham and beamline scientist Yongfeng Hu to advance the new technology using in-situ X-ray absorption spectroscopy techniques at Canadian Light Source – Canada’s national synchrotron light source facility.

“The newly developed Li-S battery demonstrates outstanding cyclability across a wide temperature range from -20 °C to 55 °C,” says Sun. “Now we will focus on the next generation of Li-S batteries using our novel reaction mechanism and hope to have these high-energy performers available for the marketplace in the very near future.”

These findings were published in the high impact journal, Nature Communications.

Sun, a fellow of the Royal Society of Canada and the Canadian Academy of Engineering, and his Advanced Materials for Clean Energy Group was named a Highly Cited Researcher in 2018 by Web of Science. This annual list recognizes world-class researchers selected for their exceptional research performance, demonstrated by production of multiple highly cited papers that rank in the top 1 per cent by citations for field and year.

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