Market and product

Compiled by Bao Hien

Scientists at the University of Surrey (UK) have published a finding that runs counter to long-standing practice in battery manufacturing: rather than removing the water naturally present in electrode material, as standard processing dictates, leaving that water in place significantly improves the performance of sodium-ion batteries — while also opening up the possibility of using the same battery material to desalinate seawater.

A Familiar Material, an Approach That Defies Convention

The research team focused on sodium vanadium oxide, a sodium-based compound that has been known and studied for years. Under standard manufacturing practice, this material is typically heat-treated to remove the water naturally present in its structure, based on the long-held assumption that water causes problems for battery performance.

Dr. Daniel Commandeur, Research Fellow at the University of Surrey's School of Chemistry and Chemical Engineering and lead author of the study, published in the Journal of Materials Chemistry A, 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." According to him, the water-retaining material — called nanostructured sodium vanadate hydrate (NVOH) — showed much stronger performance and stability than expected, and could open up exciting new possibilities for how these batteries are used in the future.

Specific Results: Nearly Double the Capacity, Faster Charging, Stable Across Cycles

Compared with a conventionally dried control sample, the water-retaining NVOH material showed significantly higher charge storage capacity — nearly double that of standard sodium-ion cathode materials — along with faster charging rates. The material also remained stable over more than 400 charge-discharge cycles, indicating this is not a fleeting effect but a durable property that could be harnessed in practice.

Works Even in Salt Water, Doubling as Seawater Desalination

The study's second surprise came from testing the material in salt water — one of the harshest environments possible for a battery system. Not only did it continue to function effectively, the material simultaneously removed sodium ions from the saltwater solution, while an accompanying graphite electrode extracted chloride ions — a process known as electrochemical desalination.

According to Dr. Commandeur, being able to use sodium vanadate hydrate in salt water is a particularly exciting discovery, as it shows sodium-ion batteries can do more than simply store energy — they can also help remove salt from water.

Potential Applications: Complementing, Not Replacing, Lithium-Ion

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

Should the remaining technical hurdles be overcome, engineers expect sodium-ion batteries to complement rather than fully replace lithium-ion technology, serving applications where cost matters more than maximum energy density — such as grid-scale renewable energy storage or backup power systems. The added desalination capability could make the technology particularly valuable for coastal renewable energy projects, where a single system could simultaneously store solar or wind power and supply fresh water to local communities.