Scientists at the University of Surrey have made a counterintuitive breakthrough in sodium-ion battery technology that could significantly enhance energy storage and enable a novel method for water desalination. The research team discovered that intentionally retaining water within a key battery material, a practice that contradicts conventional wisdom, dramatically improves the battery’s performance, including its storage capacity and charging speed.
This development, detailed in the *Journal of Materials Chemistry A*, positions sodium-ion batteries as a more viable and sustainable alternative to the dominant lithium-ion technology. Because sodium is far more abundant and cheaper than lithium, this advancement could accelerate the adoption of cleaner energy storage for power grids and electric vehicles. The discovery also revealed an unexpected secondary function: the battery material can effectively remove salt from seawater, opening a new avenue for low-cost, electrochemical desalination.
An Unconventional Method
The core of the discovery lies in challenging a long-held assumption in battery chemistry. For years, researchers working with sodium vanadium oxide, a known material for sodium-ion batteries, have systematically removed its natural water content through heat treatment, believing moisture was detrimental to performance. The Surrey team decided to question this paradigm by preserving the water within the material’s structure.
By doing so, they created what is known as nanostructured sodium vanadate hydrate (NVOH). The presence of this structural water proved to be the key to unlocking superior performance. Lead author Dr. Daniel Commandeur, a Research Fellow at the University of Surrey, described the results as “completely unexpected,” noting that the team’s decision to challenge established practice led to a far better outcome than anticipated.
Performance and Stability Gains
The performance metrics of the hydrated NVOH material represent a significant leap forward for sodium-ion technology. In laboratory tests, the material demonstrated the ability to store nearly twice as much electrical charge as many existing sodium-ion materials. This heightened energy density brings the technology closer to the performance levels of some lithium-ion chemistries, addressing a major historical drawback.
Beyond its high capacity, the material also exhibited faster charging capabilities and robust stability. The researchers found that the battery remained stable for over 400 charge-discharge cycles, a critical benchmark for demonstrating real-world viability. Until now, sodium-ion batteries have struggled to compete with their lithium-based counterparts on performance and longevity, but these findings suggest that the gap is narrowing.
A Dual-Purpose Breakthrough
From Energy Storage to Desalination
Perhaps the most surprising outcome of the research was the material’s performance in a harsh, saline environment. When the team tested the NVOH material in salt water, it not only continued to function efficiently as a battery but also began to remove sodium and chloride ions from the solution. This process, known as electrochemical desalination, had not been previously demonstrated in this context.
This dual functionality could lead to integrated systems that address two critical global challenges simultaneously: clean energy storage and fresh water production. The ability to operate within salt water suggests that future battery designs might use seawater itself as a safe, free, and abundant electrolyte.
Future Environmental Applications
Dr. Commandeur highlighted the long-term potential of this discovery, envisioning systems that could produce fresh water as a byproduct of their normal energy storage operations. Such technology could be revolutionary for coastal or arid regions, where access to both clean energy and potable water is limited. It points toward a future where battery installations for renewable energy grids could also serve as desalination plants, fundamentally altering the economics and environmental impact of both technologies.
The Growing Sodium-Ion Market
This scientific advance arrives as the commercial market for sodium-ion batteries is beginning to accelerate. While long considered a future technology, several companies are now investing heavily in gigafactory-scale production. Industry giants like CATL and BYD have already opened massive sodium-ion battery factories, signaling a permanent shift in the energy storage landscape.
These commercial batteries are already finding their way into electric vehicles and stationary storage systems. For example, JAC Motors, in partnership with Volkswagen, began shipping an EV using sodium-ion batteries in 2023. The primary drivers for this commercial push are cost and material availability. With sodium being significantly cheaper and less geographically concentrated than lithium, the technology offers a more secure and sustainable supply chain. This new research from Surrey could provide the next-generation material needed to further boost the performance of these commercial cells.
