An international team of interdisciplinary researchers, including the Canepa Research Laboratory at the University of Houston, has developed a new type of material for sodium-ion batteries that could make them more efficient and boost their energy performance - paving the way for a more sustainable and affordable energy future.
The new material, sodium vanadium phosphate with the chemical formula NaxV2(PO4)3, improves sodium-ion battery performance by increasing the energy density - the amount of energy stored per kilogram - by more than 15%. With a higher energy density of 458 watt-hours per kilogram (Wh/kg) compared to the 396 Wh/kg in older sodium-ion batteries, this material brings sodium technology closer to competing with lithium-ion batteries.
"Sodium is nearly 50 times cheaper than lithium and can even be harvested from seawater, making it a much more sustainable option for large-scale energy storage," said Pieremanuele Canepa, Robert Welch assistant professor of electrical and computer engineering at UH and lead researcher of the Canepa Lab. "Sodium-ion batteries could be cheaper and easier to produce, helping reduce reliance on lithium and making battery technology more accessible worldwide."
The researchers created a battery prototype using the new material, NaxV2(PO4)3, demonstrating significant energy storage improvements. NaxV2(PO4)3, part of a group called "Na superionic conductors" or NaSICONs, is designed to let sodium ions move smoothly in and out of the battery during charging and discharging.
Unlike existing materials, it has a unique way of handling sodium, allowing it to work as a single-phase system. This means it remains stable as it releases or takes in sodium ions. This allows the NaSICON to remain stable during charging and discharging while delivering a continuous voltage of 3.7 volts versus sodium metal, higher than the 3.37 volts in existing materials.
While this difference may seem small, it significantly increases the battery's energy density or how much energy it can store for its weight. The key to its efficiency is vanadium, which can exist in multiple stable states, allowing it to hold and release more energy.
"The continuous voltage change is a key feature," said Canepa. "It means the battery can perform more efficiently without compromising the electrode stability. That's a game-changer for sodium-ion technology."
"Our goal is to find clean, sustainable solutions for energy storage," Canepa said. "This material shows that sodium-ion batteries can meet the high-energy demands of modern technology while being cost-effective and environmentally friendly."
A paper based on this work was published in the journal Nature Materials. Ziliang Wang, Canepa's former student and now a postdoctoral fellow at Northwestern University, and Sunkyu Park, a former student of the French researchers and now a staff engineer at Samsung SDI in South Korea, performed much of the work on this project.
Research Report:Obtaining V2(PO4)3 by sodium extraction from single-phase NaxV2(PO4)3 (1 < x < 3) positive electrode materials
Related Links
Canepa Research Laboratory at the University of Houston
Powering The World in the 21st Century at Energy-Daily.com
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