Researchers at Washington State University (WSU) and Pacific Northwest National Laboratory (PNNL) have created a sodium-ion technology they say works as well as a lithium-ion battery.
The team demonstrated a single layer sodium-ion pouch cell with a capacity of 60 mAh was able to deliver a capacity similar to some lithium-ion batteries and keep more than 80% of its charge after 1,000 cycles. The cathode capacity can go up to ~200 mAh/g (612 Wh/kg).
The scientists created a liquid electrolyte that included extra sodium ions, which created a better interaction with the cell’s layered metal oxide cathode.
The combination allows sodium ions to continually move, which prevents a layer of inactive sodium crystals building up at the surface of the cathode that stop the flow of sodium ions.
The team is working on many aspects of the technology, including scaling up material production and building multi-layer pouch cells.
The manufacturing process is in line with current lithium-ion technology, which would facilitate the laboratory to market transition.
The research, led by Yuehe Lin, professor in WSU’s School of Mechanical and Materials Engineering, and Xiaolin Li, a senior research scientist at PNNL was published in the journal, ACS Energy Letters.
Lin said. “Our research revealed the essential correlation between cathode structure evolution and surface interaction with the electrolyte.
“These are the best results ever reported for a sodium-ion battery with a layered cathode, showing that this is a viable technology that can be comparable to lithium-ion batteries.”
The researchers are now working to better understand the important interaction between their electrolyte and the cathode, so they can work with different materials for improved battery design.
They also want to design a battery that doesn’t use cobalt, another relatively expensive and rare metal.
“This work paves the way toward practical sodium-ion batteries, and the fundamental insights we gained about the cathode-electrolyte interaction shed light on how we might develop future cobalt-free or low cobalt cathode materials in sodium-ion batteries as well as in other types of battery chemistries,” said Junhua Song (pictured), lead author on the paper and a WSU PhD graduate now at Lawrence Berkeley National Laboratory.
“If we can find viable alternatives to both lithium and cobalt, the sodium-ion battery could truly be competitive with lithium-ion batteries. And, that would be a game changer.”