In the search for next-generation energy storage systems, an international team of scientists has presented a low-cost, green battery that has the potential to replace lithium-ion batteries. Compared to these, the innovative design of this sodium and sulfur battery basically multiplies the energy capacity by four, while keeping production costs at a very low level. If this is in fact the case, this technology could be seen as a very good candidate to become a replacement for current lithium chemistries.
The article in which this research is detailed has been published by the journal “Advanced Materials”. There, the manufacturing process of this kind of battery is explained, which basically falls into the category of so-called molten salt batteries, which have existed with various chemical variants for about 50 years.
Most of these batteries being researched are based on sodium-sulfur (Na-S) chemistry. They have always been considered a lower performance alternative to lithium, so their widespread use has been limited by their low energy capacity and short life cycle. In addition, another difficulty for its widespread use is that its electrodes need to be kept at high temperatures in order to ensure that the electrolyte remains in a molten liquid state.
Now a team of Chinese and Australian scientists are collaborating to develop a new version that performs better at room temperature. By using a simple pyrolysis process and carbon-based electrodes, the reactivity of sulfur and the reversibility of reactions between sulfur and sodium are improved. In this way, the new battery exhibits high energy capacity and long service life at room temperature.
The result is a battery with a power capacity of 1,017 mAh/g at room temperature, which is around four times that of a lithium-ion battery. The battery demonstrated great stability, retaining around half of this capacity after 1,000 charge and discharge cycles.
According to its creators, the Na-S battery is also a less toxic alternative to lithium-ion batteries. These - present in electronic devices with small batteries and in high-capacity storage systems - are very expensive to manufacture and at the same time complicate recycling.
"Our sodium battery has the potential to drastically reduce production costs and provide four times more storage capacity", says Shenlong Zhao, director of the research. "When the sun is not shining and the wind is not blowing, you need high-quality storage solutions that are cost-free to Earth and easily accessible locally or regionally", he added.
“We hope that by providing a technology that reduces costs we can sooner reach a clean energy horizon."– Dr. Shenlong Zhao, University of Sydney#GlobalCarbonFeeAndDividendPetition https://t.co/csrWOg3tQ2— Keith McNeill (@KeithMcNeill6) December 11, 2022
After showing off their technology in the lab using prototype button cell batteries, the researchers are now working on pouch-cell versions while also looking for a path to commercialization.
There is another team of experts behind a similar development, led by the University of Glasgow, where the current director of the project, Professor Lee Cronin, works. With him, the researchers managed to develop the first electrochemical cell with the right 3D structure necessary for its functioning, without the need to resort to costly techniques. Moreover, they understood the reaction mechanism that was allowing the battery's optimal performance.
The experts also emphasize the environmental impact of their invention, since the materials used in the manufacturing process are not toxic, as it happens with other types of batteries.
In conclusion, this sodium-sulfur battery offers high capacity at a relatively low cost as compared to lithium-ion batteries; and is less toxic, making it a great candidate for replacing current lithium chemistries in many applications. The research team is now focusing on scaling up their battery to larger formats and are looking for partners to help make it a commercial reality.
Nico Caballero is the VP of Finance of Cogency Power, specializing in solar energy. He also holds a Diploma in Electric Cars from Delft University of Technology in the Netherlands, and enjoys doing research about Tesla and EV batteries. He can be reached at @NicoTorqueNews on Twitter. Nico covers Tesla and electric vehicle latest happenings at Torque News.