Researchers in Australia believe they have solved one of the key problems holding back the battery of the future, a breakthrough that would allow them to develop cells that could run a smartphone for four days.
Lithium-sulphur batteries can theoretically store six times as much energy as the lithium-ion batteries currently used in phones and electric vehicles, but that extra power can cause them to swell and break. The international research team discovered a simple tweak to the manufacturing process, which they said fixes the problem.
Their patented design was published in Science Advances earlier this week. A stack of battery prototypes have been built in Germany and will be tested in electric cars in the next few months. The team have already fielded calls from companies around the world, including electric vehicle manufacturers keen to harness the technology.
"This technology is the heir-apparent to current batteries," said Dr Mahdokht Shaibani, the Monash University engineer who led the team. "We have proven prototypes, and that makes us and the whole industry very excited."
Lithium-ion batteries come with inherent problems: they are expensive, can explode and die after a certain number of uses. Scientists have improved their efficiency, but they're starting to reach their limits. And cobalt, a key ingredient, is mined mostly in the Congo, often by child labourers. But they remain state of the art because there is nothing better available.
Labs and companies around the world are working on several alternatives, including lithium-sulphur batteries. Sulphur is cheap, abundant and can theoretically hold six times more power at the same weight. "That’s the irony," said Dr Shaibani. Lithium-sulphur batteries can hold so much power the sulphur swells up to almost twice its original size and breaks. Despite keen interest, that’s prevented commercialisation so far.
The team believe they may have solved the swelling problem with a simple tweak to how the electrode, the end of the battery that holds the charge, is made. Factories make electrodes by mixing carbon and sulphur together into a wet paste, which then dries. Dr Shaibani’s team found that slowly mixing the ingredients with only a tiny bit of water produced a thick slurry – a bit like mixing detergent powder with a drop of water.
Under the microscope, the team discovered the slurry was filled with microscopic holes, like Swiss cheese. That meant the sulphur particles could swell up without breaking as they fill with charge.
"It gives the sulphur particles some room to breathe," said Dr Shaibani.
Most research on sulphur batteries tries to solve problems using exotic materials or impractical techniques. That’s why industry is not picking it up, said Dr Shaibani.
"There have been over 8000 papers published in this field since 2010. Most of them are claiming breakthrough after breakthrough," she noted.
"I tried to use a solution that industry would accept: cheap materials, similar design."
A lab in Germany has been manufacturing prototype cells using the new technology. Dr Shaibani’s team has now received $1.1 million from the federal government to test the cells in electric cars this year. They hope to have a commercial product within two to four years. Dr Shaibani’s research is partially funded by Cleanfuture Energy, a renewable energy company that hopes to use the technology to develop better storage batteries.
One of the reasons I am so confident that battery costs will continue to decline is the extensive research taking place around the world to improve them and to improve their energy density. And if the lithium-sulphur batteries work, then electric planes will go mainstream. The sustained yearly fall in battery costs will mean that EVs have the same sticker price as petrol (gasoline) cars, and that storage for the grid will become cheap.
Here's Smart Energy International's take on the new LI-S batteries:
Monash University researchers are on the brink of commercialising the world’s most efficient lithium-sulphur (Li-S) battery, which could outperform current market leaders by more than four times, and power Australia and other global markets well into the future.
The battery has the potential to power a phone for five continuous days, or enable an electric vehicle to drive more than 1000km without needing to “refuel”.
Dr Mahdokht Shaibani from Monash University’s Department of Mechanical and Aerospace Engineering led an international research team that developed an ultra-high capacity Li-S battery that has better performance and less environmental impact than current lithium-ion products.
Using the same materials in standard lithium-ion batteries, researchers reconfigured the design of sulphur cathodes so they could accommodate higher stress loads without a drop in overall capacity or performance.
Attractive performance, along with lower manufacturing costs, abundant supply of material, ease of processing and reduced environmental footprint make this new battery design attractive for future real-world applications, according to Associate Professor Matthew Hill.
The researchers have an approved filed patent (PCT/AU 2019/051239) for their manufacturing process, and prototype cells have been successfully fabricated by German R&D partners Fraunhofer Institute for Material and Beam Technology.
Some of the world’s largest manufacturers of lithium batteries in China and Europe have expressed interest in upscaling production, with further testing to take place in Australia in early 2020.
The study was published in Science Advances on Saturday, 4 January 2020 – the first research on Li-S batteries to feature in this prestigious international publication.
And here's an article on Li-S batteries from Wikipedia.
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| Associate Professor Matthew Hill, Dr. Mahdokht Shaibani and Professor Mainak Majumder (Image: Monash University) |
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