Credit: Tess Peterson/Michigan Tech
The defect danger zone is a window of physical defect dimensions defined by the stress relief competition between diffusion and dislocation motion. The worst-case scenario is a physical interface defect (a micro crack, pore or surface roughness) that is too big for efficient stress relief by diffusion but too small to enable stress relief by dislocation motion. In this reverse Goldilocks problem, high stresses within the lithium can cause the solid electrolyte and the whole battery to catastrophically fail.