Image Courtesy: Shutterstock
Scientists have discovered that keeping water inside a sodium-ion battery material, something researchers have long tried to avoid, can nearly double its energy storage capacity while opening the door to batteries that could one day help turn seawater into fresh water.
The breakthrough comes from researchers at the University of Surrey, who found that leaving naturally occurring water molecules inside a sodium vanadium oxide material dramatically improved its performance instead of degrading it. The findings were published in the Journal of Materials Chemistry A, challenging a long-standing assumption in battery research.
Sodium-ion batteries are widely viewed as a promising alternative to lithium-ion technology because sodium is far more abundant and less expensive. While they operate in a similar way by moving charged ions between two electrodes, sodium-ion batteries have struggled to match lithium batteries in energy density, charging speed, and longevity.
The Surrey team focused on a material known as nanostructured sodium vanadate hydrate, which naturally contains water within its crystal structure. Instead of removing that water through heat treatment, the researchers tested the material in its hydrated form.
The results exceeded expectations. Laboratory tests showed the hydrated material stored nearly twice as much charge as conventional sodium-ion cathodes, charged more quickly, and maintained strong performance for more than 400 charge cycles. According to lead author Dr. Daniel Commandeur, the findings were unexpected because researchers have traditionally considered moisture harmful to battery materials.
The team also tested the material in salt water, where it continued functioning effectively. Even more surprising, the battery began removing dissolved salt from the water by drawing sodium ions into one electrode while a graphite electrode captured chloride ions. This process, known as electrochemical desalination, suggests future batteries could potentially store renewable energy while producing fresh water.
Although the technology remains in the early research stage, it could eventually benefit coastal regions with abundant seawater and renewable energy resources. Future systems might combine grid-scale energy storage with water purification, offering two essential functions in a single device.
If confirmed through further development, the discovery could strengthen the case for sodium-ion batteries as a lower-cost, more sustainable alternative to lithium-based systems while simplifying manufacturing by eliminating the need to remove water from the battery material.
