New material improves efficiency of sodium-ion batteries

Scientists from Skoltech and Lomonosov Moscow State University in Russia have produced a new material for sodium-ion batteries as an alternative to the rechargeable lithium-ion technology currently being used. The material, a powder of sodium-vanadium phosphate fluoride with a specific crystal structure, could be employed in battery cathodes to offer enhanced energy storage capacity and efficiency.

With lithium-ion batteries becoming increasingly ubiquitous, powering so much of the new portable electronics and electric vehicles being developed, as well as storing the energy produced by wind farms, this is driving greater demand for lithium resources. The price of lithium is on the increase, and its production is problematic as ore deposits are unevenly distributed around the world, and its storage capacity can also be a problem. However, as reported in the journal Nature Communications [Shraer et al. Nat. Commun. (2022) DOI: 10.1038/s41467-022-31768-5], this new high-quality cathode material made from the more abundant alkali metal sodium offers 10–15% improved energy efficiency than many counterparts and is resistant to low temperatures.

Although sodium-ion battery technology is still quite new, the basic architecture of the battery cell is similar, with different materials needed for components such as the cathode. The researchers used solid-state chemistry design to identify the material, which compares well with the class of layered materials for cathodes as it provides about the same capacity and greater stability, offering longer life and higher cost-efficiency.

Theory helped the team find the basic formula for a material able to provide the required high energy storage capacity, before identifying which crystal structure would achieve that potential. The specific compound and crystal structure was synthesized using low temperature ion exchange. As co-author Stanislav Fedotov said “Higher energy storage capacity is just one of the advantages of this material. It also enables the cathode to operate at lower ambient temperatures”. 

The team had been investigating how to develop affordable battery technology based on cheap and abundant elements as an alternative to lithium-ion batteries in fast growing large-scale applications such as big electric transport and stationary storage. As Fedotov told Materials Today, “This research provides a simple and direct synthesis approach to create new electrode materials which were considered metastable or even non-existing. The development of such materials in turn may pave the way to enhance battery performance significantly.”

The team is now looking to modify the material to unleash its theoretically possible properties, and to further develop and perfect this and relative materials as advanced electrodes for sodium-ion batteries.

“This research provides a simple and direct synthesis approach to create new electrode materials which were considered metastable or even non-existing. The development of such materials in turn may pave the way to enhance battery performance significantly.”Stanislav Fedotov