How extreme cold can crack lithium-ion battery materials, degrading performance

Lithium ion batteries are a spot celebrated for their mediocre cold-weather performance, and that has consequences for immoderate of their astir important applications—everything from starting an electrical car successful a Wisconsin wintertime to flying a drone connected Mars.

Now, researchers astatine the Department of Energy's SLAC National Accelerator Laboratory person identified an overlooked facet of the problem: Storing lithium-ion batteries astatine below-freezing temperatures tin ace immoderate parts of the artillery and abstracted them from surrounding materials, reducing their electrical retention capacity.

SLAC idiosyncratic Yijin Liu and postdoctoral chap Jizhou Li made the find portion looking astatine the cold-weather show of the cathode, the portion of the artillery electrons travel into erstwhile it's successful use. Initial studies recovered that storing cathodes astatine temperatures beneath zero degrees Celsius led batteries to suffer up to 5% much of their capableness aft 100 charges than batteries stored astatine warmer temperatures.

To recognize why, the researchers turned to a operation of X-ray investigation methods astatine SLAC's Stanford Synchrotron Radiation Lightsource and instrumentality learning techniques that Li has been moving connected implicit the past respective years. The operation allows them to place idiosyncratic cathode particles—meaning the squad could survey thousands of particles astatine once, compared to conscionable the fistful they could place with their eyes alone.

Together, those methods revealed that cold temperatures were shrinking the meatball-like particles wrong the cathode and successful the process cracking them—or making existing cracks adjacent worse, Liu said. And, since materials disagree successful the mode they grow and declaration successful effect to changing temperatures, extreme cold was besides detaching the cathodes from surrounding materials.

The results constituent to immoderate imaginable fixes, Liu said. By looking for artillery materials that are amended matched successful presumption of their temperature response, scientists could code the detachment issue. Doing truthful could assistance amended different batteries arsenic well, since each batteries grow and declaration arsenic they vigor up and chill down. And by engineering antithetic particle structures wrong a battery—notably, gathering them up from smoother, little meatball-like particles—researchers could assistance forestall cracking and amended semipermanent lithium-ion artillery capacity.

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