Recently, researchers at Washington State University (WSU) and Pacific Northwest National Laboratory (PNNL) have developed a sodium ion battery. The energy storage capacity of this battery is comparable to the chemical performance of some commercial lithium ion batteries. This makes it possible to develop a viable battery technology using abundant and inexpensive materials.
The team reported one of the best results for sodium ion batteries to date. It can provide a capacity similar to that of some lithium-ion batteries, and can maintain more than 80% of power after 1000 cycles of charging. The research was led by Professor Lin Yuehe from the School of Mechanical and Materials Engineering at Washington State University and Li Xiaolin, a senior researcher at PNNL, and was published in the ACS Energy Communications Journal.
"This is a major development for sodium ion batteries," said Dr. Imre Guick, director of energy storage at the Department of Energy's Electricity Office, who supported PNNL's work. "In many applications, people are very interested in the potential of replacing lithium-ion batteries with sodium ions."
Lithium-ion batteries are ubiquitous and are widely used in mobile phones, laptop computers, and electric vehicles. But they are made of rare and expensive materials such as cobalt and lithium. As the demand for electric vehicles and electricity storage increases, these materials will become more difficult to obtain and may be more expensive. Lithium batteries also have problems in meeting the growing energy storage needs of the power grid.
On the other hand, sodium ion batteries, made of cheap, abundant and sustainable sodium from the earth’s oceans or crust, can be good candidates for large-scale energy storage. Unfortunately, they do not store as much energy as lithium batteries. The researchers said the key challenge is that the battery must have both a high energy density and a 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 and the sodium ions can flow smoothly and continuously，the formation of inactive surface crystals is suppressed, and finally the power generation is not hindered.
Researchers are now working to better understand the important interaction between the electrolyte and the cathode, so that they can use different materials to improve the design of the battery. At the same time, the team also wanted to design a cobalt-free battery.
The researchers said that this work paved the way for actual sodium ion batteries and provided ideas for how to develop cobalt-free or low-cobalt cathode materials in the future development of sodium ion batteries and other types of battery chemistry. Sodium-ion batteries may soon compete with lithium-ion batteries.