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A new eco-friendly water battery could theoretically last for centuries - Energy & Green Tech - Hi Tech & Innovation

Credit: Nature Communications (2026). DOI: 10.1038/s41467-026-69384-2

The problem with many types of modern batteries is that they rely on harsh chemicals to work. Not only can these corrosive liquids damage internal parts over time, but they can also leach into soil and water when disposed of, contaminating it. But researchers from the City University of Hong Kong and Southern University of Science and Technology have developed an alternative, a new kind of eco-friendly battery that runs on a solution similar to the minerals used in tofu brine.

The team describes their work in a paper published in the journal Nature Communications.

The scientists replaced traditional acids and alkalis with neutral salts of magnesium and calcium to create the electrolyte. These are the same minerals used as brine in tofu production. Keeping this liquid at a neutral pH of 7.0 prevents the type of corrosive reactions that can destroy a battery from the inside out.

Novel electrode

To complete the battery design, they replaced the negative electrode, which is often made of metal-based materials, with a special material they engineered from covalent organic polymers (COPs). They made three of these plastic-like structures and selected one named Hex TADD COP. It is built with electron-donating chemical links that make it more conductive.

The researchers paired this with a positive electrode made of Prussian blue analog, a material commonly used as a blue pigment in paints.

Next came the testing rounds. Standard batteries often fail after a few hundred or a few thousand charges, but this new version remained stable for 120,000 charge cycles. To put that in perspective, if you charged your phone once a day with this type of battery, it would theoretically last for over 300 years.

The battery also held a significant amount of power for its weight. It reached an energy capacity of 112.8 mAh/g, which is a high score for an aqueous organic battery.

"Compared to current aqueous battery systems, the new system offers exceptional long-term cycling stability and respect for the environment under neutral conditions," wrote the researchers in their paper.

The battery is good news for the environment because the liquid is neutral and the materials are non-toxic. It meets international safety standards suggesting a lower environmental risk if discarded than conventional batteries.

Next steps

While the lab results are promising, there are still a number of challenges before the prototype is ready for the real world. These include increasing the amount of energy the battery can hold in a small space and scaling up the manufacturing of the organic polymers. 

by Paul Arnold, Phys.org

edited by Gaby Clark, reviewed by Robert Egan 

Source: A new eco-friendly water battery could theoretically last for centuries