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Researchers repurpose commonplace chemical with incredible properties in new battery design: 'Exhibited remarkable cycling stability'

The research team plans to scale up production of the flow batteries.

The research team plans to scale up production of the flow batteries.

Photo Credit: Pacific Northwest National Laboratory

Scientists have created a new type of battery for grid energy storage by repurposing a chemical commonly used in water treatment plants. They say it has huge potential to increase grid resiliency. 

While solar and wind power are rapidly becoming crucial parts of our energy mix, they only effectively generate electricity when it's sunny or windy outside. This makes backup energy storage essential to having reliable power. 

According to Solar Reviews, lithium-ion solar batteries from companies such as Tesla are the most popular among homeowners for energy storage. However, there are concerns about them overheating because they contain flammable materials, and lithium extraction also poses an environmental and human health risk, per Alsym Energy.

Now, researchers from the Department of Energy's Pacific Northwest National Laboratory have addressed this problem by designing an all-liquid iron-based flow battery that can be easily scaled since iron is one of Earth's most abundant minerals. 

Plus, as Power magazine reported, iron-flow batteries offer several advantages over lithium-ion storage systems. They have a longer duration and an unlimited cycle life, are non-flammable, and have lower operating expenses. 

Researchers reported in Nature Communications that the "iron-based battery exhibited remarkable cycling stability over one thousand consecutive charging cycles while maintaining 98.7 percent of its maximum capacity."

"[It's] safe, economical, [and] water-based," the researchers said, providing another path forward to powering the nation's electric grid on clean, sustainable energy. 

Large-scale flow batteries have existed since the 1980s, but the research team says theirs is unique because it stores energy in a chemical formula that contains nitrogenous triphosphonate, used to stop corrosion at water treatment facilities.

"We were looking for an electrolyte that could bind and store charged iron in a liquid complex at room temperature and mild operating conditions with neutral pH," said senior author Guosheng Li, a senior scientist at PNNL and lead of materials development for rechargeable energy storage devices, in a news release.

Flow batteries store and release energy through the electrochemical reaction of charged iron and phosphate-based liquid electrolytes. The batteries have two chambers filled with different liquids constantly moving through them to supply the electrolytes. 

The larger the electrolyte supply tank, the more energy the flow battery can store, the scientists said. 

Since the batteries can be produced at any scale up to the size of a city block, they can serve as a reliable, safe backup energy storage system for the electric grid. 

"Our next step is to improve battery performance by focusing on aspects such as voltage output and electrolyte concentration, which will help to increase the energy density," said Li. "Our voltage output is lower than the typical vanadium flow battery output. We are working on ways to improve that."

The research team plans to scale up production of the flow batteries and other battery systems at PNNL's new facility, the Grid Storage Launchpad, which will open this year. 

The GSL will facilitate exciting breakthroughs in battery storage technology, which will help reduce the planet-warming pollution causing more extreme weather events and human health hazards, such as heat strokes and disease outbreaks.

In addition, as the renewable energy transition accelerates, energy costs for cities and residents will continue to drop, ushering in a cleaner, more equitable future.

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