Portuguese 
English 
Spanish 
5 min of reading 
0 comments 
Water-based battery created by scientists from China and Hong Kong uses magnesium and calcium salts similar to tofu brine, withstood 120,000 cycles in the lab, and aims for energy storage in electrical grids with a focus on safety, durability, and lower environmental risk.
Scientists from China and Hong Kong have developed a water-based battery with a neutral electrolyte, made with magnesium and calcium salts, similar to the brine used in tofu coagulation, which functioned for 120,000 charge cycles in laboratory tests.
The technology is not yet ready to replace batteries in cell phones, laptops, or electric cars, but it emerges as a possibility for energy storage in electrical grids, where safety, durability, cost, and ease of maintenance outweigh size and lightness. The results were published in the journal Nature Communications.
The differentiator lies in the attempt to solve one of the main problems of aqueous batteries. Although they use water-based electrolytes and are generally non-flammable, many rely on strongly acidic or alkaline liquids, capable of corroding electrodes, causing secondary reactions, generating gases like hydrogen and oxygen, and reducing the system’s lifespan.
-
It took us 30 years to confirm 6,000 exoplanets, but a single project using the Transiting Exoplanet Survey Satellite has already found over 10,000 candidates in just one year by analyzing 83 million stars with artificial intelligence.
-
OnePlus puts an 8,000 mAh battery, a 1.5K 144 Hz AMOLED display, and 3,200 Hz touch response in the Nord CE6, targeting gamers who want two and a half days away from the power outlet.
-
The US spends US$ 30 billion to replace textbooks with screens in schools and now faces a generation with declines in math, reading, and creativity.
-
Archaeologists found barley seeds, leathers, and fabrics almost 1,000 years old preserved in chambers excavated in volcanic tuff in Gran Canaria.
In the new study, researchers worked with a neutral aqueous electrolyte, with a pH of 7, similar to that of pure water. The solution uses non-flammable magnesium and calcium salts and met various safety standards for disposal, according to the tests reported by the team.
Water-based battery aims for grid storage
The search for new batteries is linked to the challenge of storing clean energy. Solar panels produce a large volume of electricity at midday, while wind turbines tend to gain strength at night and dawn, when high-altitude winds are more intense.
Cities need to store this energy for hours, days, or even longer periods, in an economically viable and environmentally sustainable way. In this scenario, a large-scale stationary battery does not need to have the compact size required by portable electronics.
Lithium-ion batteries dominate cell phones, laptops, and electric vehicles because they concentrate a lot of energy in a small space. For electrical grids, however, other characteristics can become more important, such as safety, low cost, long duration, and simple maintenance at scale.
It is at this point that aqueous batteries draw attention. Because they use water-based electrolytes, they tend to be non-flammable and cheaper than conventional lithium-ion systems, although they still face significant technical limitations.
Organic polymer helped maintain stability
A neutral electrolyte alone is not enough to create an efficient battery. The difficulty lies in finding electrodes capable of storing and releasing ions quickly, without dissolving, corroding, or losing their structure over cycles.
The team focused tests on the negative electrode, a stage where many aqueous battery designs fail. Instead of a metal-based material, scientists synthesized three covalent organic polymers, known as COPs.
These polymers are rigid, porous, carbon-rich structures formed by repeating organic units. Their function is to offer pores and active chemical sites where ions can bind during battery operation.
Among the materials evaluated, Hex-TADD-COP stood out the most. The full name is hexacetone-tetraaminodibenzo-p-dioxin covalent organic polymer, a structure with electron-donating chemical bonds.
These bonds helped ions move quickly and also reduced the operating voltage of the electrode. In tests, magnesium and calcium ions interacted reversibly with chemical sites on the polymer.
During discharge, ions bound to the material. During charge, they detached again, repeating the movement without rapid performance loss.
The spectroscopy and modeling used in the study indicated that this cycle could occur with unusual stability. In practice, the electrode maintained 72.67% of its capacity after 120,000 charge and discharge cycles.
120,000 cycles result does not mean a literal 300-year guarantee
The number of cycles drew attention because, in a simple calculation, a grid battery charged approximately once a day would take more than 300 years to reach 120,000 cycles. Still, this result does not mean that a commercial battery would function for three centuries in real operation.
Laboratory tests isolate only one type of stress. In practical use, batteries face temperature variations, manufacturing defects, contamination, drying out, swelling, packaging failures, and other problems that can reduce their lifespan.
Therefore, the data should be interpreted as a sign of very stable chemistry, not as a literal promise of a 300-year lifespan. The water-based battery demonstrated high resistance in tests, but would still need to advance to commercial application.
Another important point is energy density. The complete cell reached 48.3 watt-hours per kilogram, a lower value than that of lithium iron phosphate batteries, known as LFP, currently used in grid-scale energy storage.
LFP batteries generally range between 90 and 160 Wh/kg, with some newer cells above this range. This indicates that the new battery would likely need to be two to three times heavier to store the same amount of electricity.
Safety and disposal emerge as central points
The greater weight would be a limitation for cell phones, notebooks, and electric cars. For electrical grids, however, the battery can be placed in containers near solar power plants, wind farms, substations, and factories, where volume and weight have a different impact.
In this context, a larger technology may be acceptable if it lasts much longer, avoids flammable organic solvents, and offers lower environmental risk upon disposal. Economic viability, however, cannot yet be defined, as it depends on evaluation in mass production.
The study’s strongest environmental claim involves the complete cells, described as non-toxic and suitable for direct disposal into the environment according to current standards, including the United States’ Resource Conservation and Recovery Act.
After charge and discharge cycles, the electrolyte’s pH remained between 4.91 and 7.02. The authors also did not detect heavy metals in the electrolyte analysis after the tests.
This does not mean that used batteries can be freely discarded in rivers, fields, or landfills without regulation. In the laboratory, environmental classification depends on the specific conditions evaluated and the chemical composition tested.
Commercial devices still include packaging, current collectors, separators, binders, manufacturing residues, and other auxiliary components. Even so, the water-based battery indicates a research direction towards more durable, non-flammable systems with lower environmental risk for large-scale energy storage.
Be the first to react!