Washington State University (WSU) and Pacific Northwest National Laboratory (PNNL) researchers have created a sodium-ion battery. The team reports that the Na-Ion battery is able to deliver a capacity similar to some lithium-ion batteries and to recharge successfully, keeping more than 80 percent of its charge after 1,000 cycles.
Lithium-ion batteries are the leading battery technology, but are made from rare materials, such as cobalt and lithium. Raw materials of sodium-ion batteries are made from cheap, abundant, and sustainable sodium from the earth’s oceans or crust. However, compared to Li-Ion batteries, they don’t hold as much energy and also have trouble being recharged as would be required for effective energy storage. A key problem for some of the most promising cathode materials is that a layer of inactive sodium crystals builds up at the surface of the cathode, stopping the flow of sodium ions making the battery non-functional.
“The key challenge is for the battery to have both high energy density and a good cycle life,” said Junhua Song, lead author on the paper and a WSU PhD graduate who is now at Lawrence Berkeley National Laboratory.
The research team created a layered metal oxide cathode and a liquid electrolyte that included extra sodium ions. This combination had a better interaction with the used cathode. The cathode design and electrolyte system allowed for continued movement of sodium ions, preventing inactive surface crystal build-up and allowing for unimpeded electricity generation.
“Our research revealed the essential correlation between cathode structure evolution and surface interaction with the electrolyte,” said Yuehe Lin, professor in WSU’s School of Mechanical and Materials Engineering. “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.”
“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,” Song said. “If we can find viable alternatives to both lithium and cobalt, the sodium-ion battery could truly be competitive with lithium-ion batteries.”
Source & Image: Washington State University | news.wsu.edu
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