While lithium is the basis for batteries used in the myriad devices we use every day, it’s a limited resource that will one day run out. This one of the chief reasons why scientists have been seeking new chemistries and materials to replace the conventional lithium-ion battery.
This illustration shows the design of a sodium-ion battery invented by researchers at University of Southern Denmark as a candidate to one day replace lithium-ion battery designs. (Image source: University of Southern Denmark)
One candidate to accomplish this task is a battery based on sodium, an abundant resource found both in the earth and the ocean. It’s a new chemistry using this material that researchers at the University of Southern Denmark recently developed as a potential alternative to lithium-ion batteries.
A team led by Dorthe Bomholdt Ravnsbæk, a professor in the university’s Department of Physics, Chemistry and Pharmacy, created a new sodium-ion battery that leverages an unusual electrode material that might one day give the device the performance and longevity on-par with current lithium-ion designs.
Ravnsbæk noted the ready available of sodium, especially in seawater, as one of the key advantages for using it over lithium in battery designs. “Lithium…is a limited resource that is mined only in a few places in the world,” she said.
Another advantage a sodium-ion battery would have over lithium-ion is that the process does not require the use of cobalt, which is still needed in lithium-ion batteries. There are ethical reasons not to use cobalt, as most of it used today in batteries is mined in the Democratic Republic of Congo, where workers in the mines—often children—work in terrible conditions.
Despite these disadvantages, lithium still provides one of the most reliable and high-performance materials for batteries. To create energy storage comparable with current designs has inspired researchers to play with new materials that might not currently be in use for this purpose.
That was certainly the case with Ravnsbæk and her team, which used an electrode based on iron, manganese and phosphorus to help create an efficient battery design.
The manganese in particular showed promise to improve the voltage and capacity of the battery, researchers said. That material can significantly change the transformations that occur at the atomic level during the discharge and charge, bolstering battery performance.
The result of the reaction was not what researchers expected, Ravnsbæk noted. “Similar effects have been seen in lithium-ion batteries, but it is very surprising that the effect is retained in a sodium-ion battery, since the interaction between the electrode and sodium ions is very different from that of lithium ions,” said Ravnsbæk.
The team published a on their research in the journal ACS Applied Energy Materials.
One current limitation to the design from the Danish team is that it can only be used in large batteries, researchers said. While this design may not be well-suited for a mobile device, it can be put to good use in other ways.
To this end, and a team in China already is testing one of Ravnsbæk’s team’s designs—specifically, a gigantic 100 kWh lithium-ion battery that is comprised of more than 600 connected sodium-ion battery cells. The battery is being used to provide power to the building that houses the Yangtze River Delta Physics Research Center.
Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.