A team of researchers at the University of California, Riverside have taken large steps toward creating a coating for lithium batteries that could improve their lifespan. If the batteries are covered by an organic compound coating called methyl viologen, it eliminates dendrite growth and increases the battery lifetime by three times.
Lithium-ion batteries are a standard in laptops, smartphones and electric cars. The anodes of lithium batteries are generally made with graphite or a similar carbon-based material. But carbon-based material performance is limited because of its weight and energy density. Right now, research is being focused on developing lithium metal anodes because, if successful, they will increase battery capacity five to ten times longer. Lithium-metal anodes are also lighter and less expensive than the current anodes in use.
However, these kinds of anodes present a problem: Lithium is made with metal that uncontrollably grows dendrites, microscopic fibers that look like tree sprouts, during charge cycles. This is an issue because the dendrites lower the battery performance and can potentially short circuit and catch on fire.
The development of the methyl viologen coating has the potential to change the life of lithium ion batteries completely. This coating eliminates dendrite growth, increasing the battery life by more than three times its current lifespan. The coating can be dissolved in the electrolytes in charged states. When the molecules meet the lithium metal, they are reduced to form a stable coating on the metal electrode. The methyl viologen is very low cost and can be scaled up.
"This has the potential to change the future," said Chao Wang, an adjunct assistant professor of chemistry at UC Riverside who is the lead author of the paper. "It is low cost, easily manipulated and compatible with the current lithium ion battery industry."
By creating a stable operation of lithium metal anodes, researchers have enabled the development of the next generations of high-capacity batteries, including lithium metal batteries and lithium air batteries.
The paper is called, “In Situ Formation of Stable Interfacing Coating for High Performance Lithium Metal Anodes”. It was published in the journal Chemistry of Materials.