The U.S. has a wave of hydro, solar wind energy projects in the works. To harness renewable energy, developers will need better battery storage. But the parts needed are expensive and hard to find. The author of a study at Brookhaven National Lab on Long Island might have found a cheaper alternative that’s also safe for the environment.
“We've focused on using water for our batteries,” said Esther Takeuchi, the chief scientist for the U.S. Department of Energy at Brookhaven National Laboratory.
To understand water-based batteries, she said it's important to know the basics of how batteries work.
“What happens inside the battery is that there's some kind of a liquid that contains a salt,” Takeuchi explained, mimicking turning on a small handheld device that needs batteries.
“The electrons (the salt with an electric charge) flow from the negative electrode to the positive electrode. So the electrons are leaving the negative and traveling through the device, and then they're going back into the positive side of the battery… those electrons moving are electricity,” she said.
The salt in most traditional batteries are lithium-ions. Takeuchi said the trouble starts with cost. Building enough lithium-ion batteries for renewable energy storage can be expensive.
“There's like one or two places on Earth where you can actually mine these elements. And one of the elements, cobalt, that's used in lithium-ion, the biggest mines are all located in Congo, in Africa,” she said.
The salt Takeuchi uses is made of manganese and zinc, instead of lithium.
“If these batteries are really big, can we use elements, can we use materials that are not very dangerous, that are Earth abundant, that are readily available?” she said.
Another issue: the liquid in lithium-ion batteries is flammable. So, Takeuchi’s battery uses water as a base.
“Let's say this thing started leaking,” Takeuchi said. “Well, you know, so maybe it's water with some kind of a salt and salt in it, but that's different than having something that's highly flammable coming out of the battery.”
Her team is not the first to study this water-based battery. But they did figure out how to measure the chemical reaction so that it might be reusable. Other studies using similar batteries did not consider the specific chemical reaction between manganese and water. Takeuchi’s team found the salt dissolves and solidifies in water depending on its charge.
"Once we realized what it was, then it allows a whole new way to think about this battery,” Takeuchi said. “So if we want to further develop its battery now at least we know what to try to control.”
These results could help expand storage of renewable energy: A feat fit for Takeuchi’s background.
President Obama awarded Takeuchi the National Medal of Technology in 2009 for developing the tiny battery that powers most of the world’s lifesaving pacemakers and personal defibrillators.
Not a task too small to develop a much larger battery to harness the power of solar and wind energy.
Esther Takeuchi, the chief scientist for the U.S. Department of Energy at Brookhaven National Laboratory and a professor at Stony Brook University on Long Island.
