Sodium could replace lithium for more cost-efficient battery storage, scientists say

It costs roughly $15,000 a ton to mine lithium. Harvesting sodium costs just $150 per ton.
By Brooks Hays  |  Oct. 10, 2017 at 11:30 AM
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Oct. 10 (UPI) -- Researchers at Stanford University have built a sodium-based battery that can store just as much energy as a lithium-ion battery, but at a significantly reduced cost.

Lithium-ion batteries have been the standard bearer for the last 25 years. But lithium is becoming increasingly scarce and mining costs are steep.

Sodium -- which also hosts ions that can be moved from a cathode to an anode across an electrolyte to create a current -- is more abundant and cheaper to process.

The new sodium-based battery may never meet the needs of electric car makers, but researchers believe it could help store the energy harvested by sustainable sources, like solar cells and wind turbines.

"Nothing may ever surpass lithium in performance," Zhenan Bao, a chemical engineer at Stanford, said in a news release. "But lithium is so rare and costly that we need to develop high-performance but low-cost batteries based on abundant elements like sodium."

It costs roughly $15,000 a ton to mine lithium. Harvesting sodium costs just $150 per ton.

In the newly designed sodium-ion battery, the sodium ions are attached to myo-inositol, a common chemical compound that can be derived from rice bran or the liquid byproduct leftover by the corn milling process.

The new pairing of sodium ions and myo-inositol significantly improved the latest iteration of their sodium-based battery, more efficiently moving ions from the cathode cross the electrolyte to the phosphorous anode.

In addition to making cost-performance comparisons between lithium and sodium, Bao and her colleagues made sure to analyze how sodium ions attach and detach from the cathode during the charging and discharging process. Their insights helped improve the battery's design.

But researchers say they need to do more tests to determine how the battery system's volumetric energy density compares to a lithium-ion battery. Scientists want to know how big the sodium-ion battery needs to be to store as much energy as a lithium-ion battery.

Bao and her colleagues also plan to improve upon the design of their battery's phosphorous anode.

The scientists detailed their early success in a new paper published this week in the journal Nature Energy.

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