Renewable energy from solar and wind is transforming how we power our world. But for these energy sources to reach their full potential, we need better batteries to store the electricity they produce.
Now, engineers at the University of Wisconsin-Madison have created a special chemical additive that could make this possible.
Their invention improves the performance of a type of battery called a bromide aqueous flow battery, a safer and more affordable alternative to the large lithium-ion batteries currently used to store energy for the grid.
The team's research was published in Nature on October 23, 2024.
Bromide flow batteries hold promise because they use cheap, widely available bromide ions in a water-based liquid system.
These batteries have the potential to be scalable, sustainable, and safe.
However, in practice, they face several issues. Bromide ions can leak through the battery's membrane, reducing efficiency.
They can also form a sticky mess that sinks to the bottom of the liquid or even create toxic gas.
The UW-Madison researchers, led by assistant professor Dawei Feng, graduate student Gyohun Choi, and recent Ph.D. graduate Patrick Sullivan, tackled these problems with a clever solution. They developed a water-soluble additive that acts like a "trap" for the bromide ions.
The additive keeps the ions stable and prevents them from leaking through the battery's membrane or causing other issues.
By carefully designing and testing 13 different molecules, the team found one that solved the battery's major challenges.
This additive makes the bromide ions form larger, stable structures, so they stay in the liquid and don't create toxic gas or sticky residues.
Batteries with this additive performed far better than those without it, lasting nearly two months without losing efficiency -- compared to just one day for batteries without the additive.
This breakthrough could make bromide flow batteries a viable alternative to lithium-ion batteries, which are expensive, prone to safety risks like fires, and depend on a complicated global supply chain.
Bromide batteries, on the other hand, are made with widely available materials and could offer a safer, cheaper solution for long-term energy storage.
The research team is continuing to refine the technology. Choi will focus on understanding how the additive works, while Sullivan, now CEO of the renewable energy company Flux XII, is exploring how to bring this innovation to market.
The additive has already been successfully produced in large quantities, paving the way for more reliable and affordable energy storage systems.
This invention could help us store renewable energy more efficiently and build a greener, more sustainable future.