Matthieu Bugnet

Inside each tiny particle that makes up the cathode of a sodium-ion battery, sodium is unevenly distributed — like sugar clumping in tea. This reduces the battery's capacity and lifespan. To see this hidden landscape, scientists used X-ray microscopy and trained artificial intelligence to interpret the data.

A taut string sounds higher, a slack one lower. In quantum dots, the crystal lattice plays the role of the string: compression or stretching changes the color of the emitted light. The trouble is that during nanowire growth, each dot ends up with its own random strain, so their "strings" sound out of tune.