A Different Way to Make a Cathode May Mean Better Batteries

Estimated reading time: 4 minutes

Lithium nickel manganese cobalt oxide, or NMC, is one of the most promising chemistries for better lithium batteries, especially for electric vehicle applications, but scientists have been struggling to get higher capacity out of them. Now researchers at Lawrence Berkeley National Laboratory (Berkeley Lab) have found that using a different method to make the material can offer substantial improvements.

Working with scientists at two other Department of Energy (DOE) labs—Brookhaven National Laboratory and SLAC National Accelerator Laboratory—a team led by Berkeley Lab battery scientist Marca Doeff was surprised to find that using a simple technique called spray pyrolysis can help to overcome one of the biggest problems associated with NMC cathodes—surface reactivity, which leads to material degradation.

These 3D elemental association maps generated using transmission X-ray tomography show the cathode material made by Berkeley Lab Marca Doeff and her team using spray pyrolysis.

“We made some regular material using this technique, and lo and behold, it performed better than expected,” said Doeff, who has been studying NMC cathodes for about seven years. “We were at a loss to explain this, and none of our conventional material characterization techniques told us what was going on, so we went to SLAC and Brookhaven to use more advanced imaging techniques and found that there was less nickel on the particle surfaces, which is what led to the improvement. High nickel content is associated with greater surface reactivity.”

Their results were published online in the premier issue of the journal Nature Energy in an article titled, “Metal segregation in hierarchically structured cathode materials for high-energy lithium batteries.” The facilities used were the Stanford Synchrotron Radiation Lightsource (SSRL) at SLAC and the Center for Functional Nanomaterials (CFN) at Brookhaven, both DOE Office of Science User Facilities.

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