With great power comes great color SnO
2 nanocrystals coated with protective polydopamine appear red when fully charged and green in a discharged state. In their Communication on
page 1869 ff., Z.
Lin et al. describe polymer-template-guided formation of SnO
2 nanocrystals. The material was app
lied as an anode in
lithium-ion batteries––achieving excellent rate capabi
lity, long-term stabi
lity, and operabi
lity over a range of current densities.