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 groupβs 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 teamβs 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.
βWhen the sun isnβt shining and the breeze isnβt blowing, we need high-quality storage solutions that donβt cost the Earth and are easily accessible on a local or regional level,β said lead researcher Dr Shenlong Zhao from the University of Sydney. βWe 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 teamβs 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 gβ1 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 teamβs paper as βunprecedented.β
βOur sodium battery has the potential to dramatically reduce costs while providing four times as much storage capacity,β said Dr Zhao. βThis is a significant breakthrough for renewable energy development which, although reduces costs in the long term, has had several financial barriers to entry.β
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.
βIt probably goes without saying but the faster we can decarbonize β the better chances we have of capping warming,β said Zhao. βStorage solutions that are manufactured using plentiful resources like sodium β which can be processed from sea water β also have the potential to guarantee greater energy security more broadly and allow more countries to join the shift towards decarbonization.β
The research was published in the journal Advanced Materials.
Source: University of Sydney
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...
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.