Under study were sodium-ion oxide cathodes made from transition-metal core-shell particles – a nickel-rich core surrounded by a cobalt and manganese-rich shell.

“The manganese-rich surface gives the particle its structural stability during charge-discharge cycling,” according to the lab. “The nickel-rich core provides high capacity for energy storage.”

Energy storage capacity steadily declined during cycling, which was narrowed down to cracks developing in the cathode particles due to strain arising between the shell and core in the particles.

Further work revealed that these cracks were initiated deep within the particles, and not, as had been expected, at the surface. It also revealed a way to stop the cracks.

The two sentences above bely the huge research effort required to make the discovery, which, amongst other equipment, required two of the world’s most powerful synchrotrons and, to understand their data, a world top-50 super-computer: Argonne’s Advanced Photon Source, Brookhaven National Laboratory’s National Synchrotron Light Source II and Argonne’s Polaris computer.

“Prevent