A new “yolk-and-shell” nanoparticle could boost the capacity and power of lithium-ion batteries. The gray sphere at center represents an aluminum nanoparticle, forming the “yolk.” The outer light-blue layer represents a solid shell of titanium dioxide, and the space in between the yolk and shell allows the yolk to expand and contract without damaging the shell. In the background is an actual scanning electron microscope image of a collection of these yolk-shell nanoparticles.
