This clip shows a benchtop version of the world's smallest battery — its anode a single nanowire one seven-thousandth the thickness of a human hair — that has been created by a team of researchers at Sandia National Laboratories.
Unlike a conventional battery, this one expands to more than twice its normal length when it is recharged, and shrinks when discharged. The battery expands because as electrons are added to it, the lithium atoms get forced into the lattice between tin oxide atoms. Some of the lithium forms lithium oxide, while the tin oxide reduces to tin. Lithium oxide is a much larger molecule than Lithium by itself, so the filament gets longer and also twists under the stress.