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| Lead author and battery researcher Gabriel Nambafu assembles a test flow battery apparatus. Photo Credit: Andrea Starr | Pacific Northwest National Laboratory |
A commonplace chemical used in water treatment facilities has been repurposed for large-scale energy storage in a new battery design by researchers at the Department of Energy’s Pacific Northwest National Laboratory. The design provides a pathway to a safe, economical, water-based, flow battery made with Earth-abundant materials. It provides another pathway in the quest to incorporate intermittent energy sources such as wind and solar energy into the nation’s electric grid.
The researchers report in Nature Communications that their lab-scale, iron-based battery exhibited remarkable cycling stability over one thousand consecutive charging cycles, while maintaining 98.7 percent of its maximum capacity. For comparison, previous studies of similar iron-based batteries reported degradation of the charge capacity two orders of magnitude higher, over fewer charging cycles.
Iron-based flow batteries designed for large-scale energy storage have been around since the 1980s, and some are now commercially available. What makes this battery different is that it stores energy in a unique liquid chemical formula that combines charged iron with a neutral-pH phosphate-based liquid electrolyte, or energy carrier. Crucially, the chemical, called nitrogenous triphosphonate, nitrilotri-methylphosphonic acid or NTMPA, is commercially available in industrial quantities because it is typically used to inhibit corrosion in water treatment plants.
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