  We investigate the structural and electronic properties of Li-intercalated
monolayer graphene on SiC(0001) using combined angle-resolved photoemission
spectroscopy and first-principles density functional theory. Li intercalates at
room temperature both at the interface between the buffer layer and SiC and
between the two carbon layers. The graphene is strongly $n$-doped due to charge
transfer from the Li atoms and two $\pi$-bands are visible at the
$\bar{K}$-point. After heating the sample to 300$^\circ$C, these $\pi$-bands
become sharp and have a distinctly different dispersion to that of
Bernal-stacked bilayer graphene. We suggest that the Li atoms intercalate
between the two carbon layers with an ordered structure, similar to that of
bulk LiC$_6$. An AA-stacking of these two layers becomes energetically
favourable. The $\pi$-bands around the $\bar{K}$-point closely resemble the
calculated band structure of a C$_6$LiC$_6$ system, where the intercalated Li
atoms impose a super-potential on the graphene electronic structure that opens
pseudo-gaps at the Dirac points of the two $\pi$-cones.
