Washington State University develops sodium-ion battery that rivals lithium-ion

Washington State University (WSU) and Pacific Northwest National Laboratory (PNNL) researchers have developed a sodium-ion battery that can store energy as well as some commercial lithium-ion battery chemistries, making it possible to develop a potentially viable battery technology using abundant and inexpensive materials.

The team reported one of the best results to date for a sodium-ion battery. It was able to deliver a capacity similar to some lithium-ion batteries and retain more than 80 percent of its charge after 1,000 cycles of charging. The research, led by Professor Yuehe Lin of WSU's School of Mechanical and Materials Engineering and Xiaolin Li, a senior researcher at PNNL, was published in the journal ACS Energy Letters.

"This is a major development for sodium-ion batteries," said Dr. Imre Goecker, director of energy storage in the Department of Energy's Office of Electricity, which supported this work at PNNL. "There is a lot of interest in the potential of sodium-ion to replace lithium-ion batteries in many applications."

Lithium-ion batteries are ubiquitous, used in everything from cell phones to laptops to electric cars . But they are made from rare and expensive materials such as cobalt and lithium. As demand for electric cars and electricity storage increases, these materials will become harder to come by and potentially more expensive. Lithium batteries also have problems meeting the growing energy storage needs of the electric grid.

On the other hand, sodium-ion batteries, made from cheap, abundant and sustainable sodium from Earth's oceans or crust, could be good candidates for large-scale energy storage. Unfortunately, they don't store as much energy as lithium batteries . The key challenge, the researchers say, is to get batteries that have both high energy density and good cycle life.

The research team designed and manufactured a layered metal oxide cathode and a liquid electrolyte containing additional sodium ions. The liquid electrolyte can interact well with the cathode, allowing sodium ions to flow smoothly and continuously inside, while the formation of inactive surface crystals is suppressed, ultimately allowing unimpeded power generation.

The researchers are now working to better understand the important interactions between the electrolyte and the cathode so they can improve the battery design with different materials. The team also wants to design a cobalt-free battery.

The researchers say this work paves the way for practical sodium-ion batteries, providing ideas for how to develop cobalt-free or low-cobalt cathode materials in future sodium-ion batteries and other types of battery chemistries. Sodium-ion batteries may soon be truly competitive with lithium-ion batteries.