Scientists have developed a battery powered by sulphur, air, water and salt – all readily available materials – which is 10 to 100 times cheaper to produce than batteries currently on the market and can store twice as much energy as widely used lead-acid batteries.
The new technology has the potential to reduce the cost of storing renewable energy while allowing more it to be captured. The prototype of the new battery is described in a study published in the journal Joule.
"It has become increasingly clear that in order for renewable energy to become the main part, if not all, of our electricity generation system, it needs to match the output of the demand that we have as a society," said senior author Yet-Ming Chiang from MIT's Department of Materials Science and Engineering.
"We think that this work helps move us in the right direction and creates more hope that this is possible, but we need to push it ahead very quickly because we don't have a lot of time."
One of the main drawbacks of renewable energy is its variability and so being able to store energy during down times is essential for uninterrupted energy flow.
Currently, only a very small percentage of all the renewable energy generated is actually stored because of the high cost this entails.
In developing the battery, Chiang and his team looked at how to create a storage unit with a low cost per unit of energy metric, measured in US dollars per kilowatt hour ($/kWh). Current battery costs are expensive often ranging between $10 and $100/kWh as materials commonly need to be sourced from around the world.
The researchers were particularly interested in looking at the potential of sulphur – an abundant non-metal that is a product of natural gas use – as a core component of a lightweight and inexpensive storage battery.
Batteries all consist of a positive anode, a negative cathode, and an electrolyte to carry the electrical charge. The team wanted to explore whether sulphur could be used as the cathode and water as the electrolyte.
"We went on a search for a positive electrode that would also have exceptionally low cost that we could use with sulphur as the negative electrode," Chiang said. "Through an accidental laboratory discovery, we figured out that it could actually be oxygen, and therefore air. We needed to add one other component, which was a charge carrier to go back and forth between the sulphur and air electrode, and that turned out to be sodium." These findings resulted in a battery which cost just $1/kWh to produce.
Looking forward, the researchers plan to improve the battery by making it more efficient, cheaper and increasing its lifespan.