Water Instead of Lithium: The “Eternal” Battery Ready to Conquer the World

American scientists have developed a new battery design based on a chemical compound commonly used at water treatment plants. This innovation aims to meet the growing demand for renewable energy sources such as wind and solar power.

The core of this new development is a prototype iron-flow battery that demonstrates unmatched charge cycle stability. According to the laboratory’s statement, the battery “showed outstanding cycle stability, withstanding more than 1,000 consecutive charge cycles while retaining 98.7% of its maximum capacity.” This marks significant progress compared to previous versions, which suffered from considerable degradation.

Another distinctive feature of the battery is the use of a unique liquid chemical formula that charges iron with a pH-neutral phosphate electrolyte. The substance, a nitrogen-containing triphosphate called nitrilotri(methylphosphonic acid) (NTMP), is widely available due to its use at water treatment facilities to prevent corrosion.

The flow batteries used by the researchers feature a two-chamber design and continuous circulation of electrolyte liquids, offering a versatile solution for energy storage. These batteries are charged through an electrochemical reaction and store energy in chemical bonds, which can later be used to power electrical devices.

Advantages and Future Prospects

Unlike traditional batteries, these flow systems can be deployed at any scale—from laboratory setups to city infrastructure—and can even serve as backup generators for the power grid. The study’s authors highlighted the safety benefits of the water-based flow battery system, especially its operation at a neutral pH in water. They also noted the use of widely available reagents that had not previously been explored for flow battery applications.

Although the current energy density is 9 watt-hours per liter (Wh/L), which is lower than that of commercial vanadium systems, the PNNL battery promises further improvements. The researchers plan to enhance the battery’s performance by focusing on aspects such as output voltage and electrolyte concentration to increase energy density.