Cheap sodium-sulfur battery boasts 4x the capacity of lithium-ion

Cheap sodium-sulfur battery boasts 4x the capacity of lithium-ion
Scientists have developed a novel sodium-sulfur battery with exciting potential for renewable energy storage
Scientists have developed a novel sodium-sulfur battery with exciting potential for renewable energy storage
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Scientists have developed a novel sodium-sulfur battery with exciting potential for renewable energy storage
Scientists have developed a novel sodium-sulfur battery with exciting potential for renewable energy storage

An international team of scientists eyeing next-generation energy storage solutions have demonstrated an eco-friendly and low-cost battery with some exciting potential. The group’s novel sodium-sulfur battery design offers a fourfold increase on energy capacity compared to a typical lithium-ion battery, and shapes as a promising technology for future grid-scale energy storage.

The team’s creation falls into a category of batteries known as molten-salt batteries, which have been around in various forms for around 50 years. As the emphasis on renewable energy continues to grow, scientists are bullish on the potential of molten-salt batteries to store it, owing to their relative affordability and reliance on commonly available materials.

This could, theoretically, see them built on the larger scales needed to store vast amounts of renewable energy. Typical versions of these rely on a sodium-sulfur chemistry and hold their electrodes at high temperatures to keep the electrolyte in a liquid molten state. Scientists in China and Australia have teamed up to develop their own version, which they say offers greatly improved performance at room temperature instead.

“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,” said lead researcher Dr Shenlong Zhao from the University of Sydney. “We hope that by providing a technology that reduces costs we can sooner reach a clean energy horizon."

Zhao and his colleagues set out to address a couple of shortcomings with current sodium-sulfur batteries, relating to their short life cycles and limited capacities, which has hindered their practicality in commercial applications. The team’s design makes use of carbon-based electrodes and a thermal degradation process known as pyrolysis to alter the reactions between the sulfur and sodium.

The result is a sodium-sulfur battery with a high capacity of 1,017 mAh g−1 at room temperature, which the team notes is around four times that of a lithium-ion battery. Importantly, the battery demonstrated good stability and retained around half of this capacity after 1,000 cycles, described in the team’s paper as “unprecedented.”

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

Having demonstrated the technology in coin cell batteries in laboratory testing, the researchers are now working on pouch cell versions as they eye a path to commercial use.

“It probably goes without saying but the faster we can decarbonize – the better chances we have of capping warming,” said Zhao. “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 decarbonization.”

The research was published in the journal Advanced Materials

Source: University of Sydney

Alan Mulder
How many times have we seen a story like this.... Promising the world but in the end nothing eventuates
Maybe this will solve the Lithium mining and supply problem. Sodium and sulphur are abundant. Watch this space!
I guess "molten salt" doesn't mean what it looks like it means. Reassuring to see that the energy capacity was listed at room temperature. And yeah, as usual wait to see how this plays out. Even if the battery lifetime is relatively short, with that high capacity it could be worth just using them and recycling. (And for a lot of applications, 500-1000 cycles is in the vicinity of 10 years...)
paul314: 𝐀𝐧𝐝 𝐟𝐨𝐫 𝐚 𝐥𝐨𝐭 𝐨𝐟 𝐚𝐩𝐩𝐥𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬, 𝟓𝟎𝟎-𝟏𝟎𝟎𝟎 𝐜𝐲𝐜𝐥𝐞𝐬 𝐢𝐬 𝐢𝐧 𝐭𝐡𝐞 𝐯𝐢𝐜𝐢𝐧𝐢𝐭𝐲 𝐨𝐟 𝟏𝟎 𝐲𝐞𝐚𝐫𝐬... Yes,but maybe more than 10 years if the energy density is higher than lithium,which would translate to fewer stops for charging.
All three comments are dead on the money -- the next-gen non-LiO battery is always beer tomorrow, never beer today. This WOULD help with the Li mining problem, if it doesn't sneakily rely on e.g. rare earths or something inside that make it just as expensive and/or difficult to remanufacture. With 4x lithium capacity per kg of battery, retaining 50% at 1000 cycles would still leave one with 2x lithium capacity, and if they WERE cheap to remanufacture/recondition to full capacity. And there might be a way of hybridizing it with e.g. a supercap front end or an integrated reconditioning cycle to extend lifetime beyond what they have tested so far.

I'm still betting heavily on lithium for the next 5-10 years though. It would take literally billions in capital investment to build a scalable manufactory for any competing battery technology, and that would likely take 3-5 years to even think of reaching anything but niche markets. The article suggests that this is still in the University, nowhere near ready for industrial prime time, and it hints at "obstacles" that may make scalable manufacture tricky. One of these is the supply of e.g. graphite, which is ALREADY a limiting factor for lithium batteries. The other is "pyrolysis" -- the use of heat to thermally decompose unwanted "stuff", e.g. the structures that interfere with battery function. It sounds like they have a battery that operates at room temperature, but that has to "go molten" when charging it up to break down those structures. That in turn means that it may not be very efficient -- requiring a lot more energy to charge than it stores -- and may be utterly unsuitable for cars and phones and so on unless one removes the battery from its heat-sensitive surroundings. And then there is the question -- just how hot DO the batteries have to get during pyrolysis? 100C? 200C? Glowing red?

I'll not hold my breath...
"Molten salt" doesn't necessarily mean "at the same high temperature that NaCl melts". Mercury melts at a much lower temperature than Tungsten, so I see no reason to assume that salts can't be molten at room temperature.

Unfulfilled promises are common, but some new developments do turn into commercial products. How many news stories were there about Li-ion batteries before they became in common use? A story about a working Na-S cell (abundant, safe materials) is better than a story about an Iridium-Fluorine cell even if the latter had good electrical characteristics.
Everything we've seen which out-denses (new word) Lithium either has low lifecycles, is heavier, or has long charge cycles. Li now boasts of 4k-8k life with 80% of original power. This sodium/sulfur batt is down to 50% power at under 1k cycles. If it's super cheap, it may funnel into some niches, at best. Panasonic just announced a potential 30% power density rise with its next gen batteries. The bar rises once again.
"only" another year or two before it goes mainstream....yeah right.
Malcolm Jacks
Can't wait, looks very promising.
Per the Naysayers we should just stop trying. Pathetic.
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