The team 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. 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 honoured with the 2017 Nobel Prize in chemistry.

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.

In cryo-EM, samples are flash frozen by dipping them into liquid nitrogen, then sliced for examination under the microscope. You can freeze a whole coin-cell battery at a particular point in its charge-discharge cycle, remove the component you're interested in, and see what is happening inside that component at an atom-by-atom scale.

You could even create a stop-action movie of battery activity by stringing together images made at different points in the cycle. Zooming in, they used a different technique to look at the way electrons bounced off the atoms in the dendrite, revealing the locations of individual atoms in both the crystal and its solid electrolyte interphase (SEI) coating. When they added a chemical commonly used to improve battery performance, the atomic structure of the SEI coating became more orderly, and they think this may help explain why the additive works.

Understanding battery fires is becoming crucial as more of them are deployed in cars and mobile gadgets.