Researchers have provided new promise for developing a lithium-metal battery with commercial viability with the invention of a new coating that would make these types of batteries safer and able to last longer.

A team of researchers at Stanford University invented the coating, which helps overcome some of the key defects that have relegated these types of batteries—which have enormous potential for energy storage—to the laboratory.

Stanford University PhD students David Mackanic, left, and Zhiao Yu in front of a battery tester they developed for lithium-metal batteries they developed using a new coating. Yu is holding a dish of already tested cells that they call the “battery graveyard.” (Image source: Mark Golden)

Lithium-metal batteries have a great risk of catching fire and also a short lifespan, which doesn’t make them viable for commercial use despite their being a good candidate for electric-vehicle (EV) batteries. Indeed, these batteries can hold at least a third more power per pound as lithium-ion batteries and also are significantly lighter because they use lithium rather than the heavier graphite for their positive charge.

To solve issues hindering the development and use of lithium-metal batteries, a team at Stanford University and SLAC National Accelerator Laboratory developed a coating that not only extends the battery’s life, but also deals with a key issue that can lead to their flammability. Zhenan Bao, a professor of chemical engineering at Stanford, and Yi Cui, professor of materials science and engineering and photon science at SLAC National Accelerator Laboratory, led the research.

“The capacity of conventional lithium-ion batteries has been developed almost as far as it can go,” Stanford PhD student David Mackanic said in a press statement. “So, it’s crucial to develop new kinds of batteries to fulfill the aggressive energy density requirements of modern electronic devices.”

One key problem with lithium-metal batteries is that they tend to develop tiny, needle-like structures called dendrites over their lifespan that pierce the separator between the battery’s positive and negative sides. These dendrites can create a short circuit within the battery’s flammable liquid, as well as just degrade the battery in general.

Avoiding the Explosion

To prevent dendrites from forming, researchers developed a coating that creates a network of molecules to deliver uniformly charged lithium ions to the electrode, they said. This prevents the occurrence of undesirable chemical reactions that typical for these batteries, researchers said.

The molecules also reduce a chemical buildup on the anode, which is one of the key reasons for the degradation of the battery’s ability to deliver power, said Zhiao Yu, another Stanford PhD student who worked on the research.

“Our new coating design makes lithium-metal batteries stable and promising for further development,” he said in a press statement.

Researchers tested their coating on the anode—the positively charged end of a lithium-metal battery–which is where dendrites typically form, and then combined specially coated anodes with other commercially available components to create a fully operational battery.

After 160 cycles, the cells the team developed still delivered 85 percent of the power that was generated during their first cycle, researchers said. In comparison, typical lithium-metal cells deliver about 30 percent after the same amount of cycles, which renders them nearly useless even if they don’t explode.

Researchers published a paper on their work in the journal Joule.

The team plans to continue to refine the design and development of the coating to increase capacity retention and testing cells over more cycles, Cui said.

Though ultimately researchers hope the coating can be used to develop lithium-metal batteries for EVs, “commercialization would likely start with consumer electronics to demonstrate the battery’s safety first,” he said in a press statement.

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.