Scientists from Stanford University and the Department of Energy's SLAC National Accelerator Laboratory have captured the first atomic-level images of finger-like growths called dendrites that can pierce the barrier between battery compartments and trigger short circuits or fires. Dendrites and the problems they cause have been a stumbling block on the road to developing new types of batteries that store more energy so electric cars, cell phones, laptops and other devices can go longer between charges.

This is the first study to examine the inner lives of batteries with cryo-electron microscopy, or cryo-EM, a technique whose ability to image delicate, flash-frozen proteins and other "biological machines" in atomic detail was honored with the 2017 Nobel Prize in chemistry.

The new images reveal that each lithium metal dendrite is a long, beautifully formed six-sided crystal - not the irregular, pitted shape depicted in previous electron microscope shots. The ability to see this level of detail for the first time with cryo-EM will give scientists a powerful tool for understanding how batteries and their components work at the most fundamental level and for investigating why high-energy batteries used in laptops, cell phones, airplanes and electric cars sometimes fail, the researchers said. They reported their findings in Science today.

"This is super exciting and opens up amazing opportunities," said Yi Cui, a professor at SLAC and Stanford and investigator with the Stanford Institute for Materials and Energy Sciences (SIMES) whose group did the research.

"With cryo-EM, you can look at a material that's fragile and chemically unstable and you can preserve its pristine state - what it looks like in a real battery - and look at it under high resolution," he said. "This includes all kinds of battery materials. The lithium metal we studied here is just one example, but it's an exciting and very challenging one."