  The ability to control heat transport with electrical signals has been an
outstanding challenge due to the lack of efficient electrothermal materials.
Previous attempts have mainly concentrated on phase-change and layered
materials and encountered various problems such as low thermal conductivities
and modest on/off ratios. Here, we demonstrate a graphene-based electrothermal
switch enabling electrically tuneable heat flow. The device uses reversible
electro-intercalation of ions to modulate the in-plane thermal conductivity of
graphene film by over thirteen-fold via electrically tuneable phonon
scattering. We anticipate that our results could provide a realistic pathway
for adaptive thermal transport enabling a new class of electrically driven
thermal devices which would find a broad spectrum of applications in aerospace
and microelectronics.
