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Sodium-ion batteries may be the answer to the future of sustainable energy storage and could be used to make drinking water out of seawater. Scientists at the University of Surrey have discovered a simple way to boost their performance—by leaving the water inside a key component rather than removing it.

Unlike lithium-ion technology, which currently dominates the energy storage market and relies on expensive, environmentally damaging materials, sodium is far more abundant and widely available. However, developing sodium-ion batteries that can compete on performance has remained a challenge.

In a study in the Journal of Materials Chemistry A, researchers detail how an existing sodium-based material, sodium vanadium oxide, can perform significantly better when the water it naturally contains is not removed.

The material—known as a nanostructured sodium vanadate hydrate (NVOH)—showed a major boost in performance, storing far more charge, charging much faster and remaining stable for more than 400 charge cycles.

In tests, the "wet" version of the material could hold almost twice as much charge as typical sodium-ion materials, placing it among the best-performing cathodes reported to date.

Dr. Daniel Commandeur, Research Fellow at the University of Surrey School of Chemistry and Chemical Engineering, and lead author of the paper, said, "Our results were completely unexpected. Sodium vanadium oxide has been around for years, and people usually heat-treat it to remove the water because it's thought to cause problems.

"We decided to challenge that assumption, and the outcome was far better than we anticipated. The material showed much stronger performance and stability than expected and could even create exciting new possibilities for how these batteries are used in the future."

The research team also tested how the material behaved in salt water—one of the most challenging environments possible. Results showed it not only continued to function effectively but also removed sodium from the solution while a graphite electrode extracted chloride—a process known as electrochemical desalination.

Dr. Commandeur added, "Being able to use sodium vanadate hydrate in salt water is a really exciting discovery, as it shows sodium-ion batteries could do more than just store energy—they could also help remove salt from water. In the long term, that means we might be able to design systems that use seawater as a completely safe, free and abundant electrolyte, while also producing fresh water as part of the process."

The breakthrough could accelerate the development of sodium-ion batteries as a viable alternative to current lithium-based technology. Using abundant, low-cost materials makes these batteries safer and more sustainable, with potential applications ranging from storing renewable energy on the grid to powering electric vehicles. The Surrey team's approach also simplifies how high-performance sodium batteries are made, helping to bring large-scale, commercially viable energy storage a step closer.