  We study the stability of Li-O compounds as a function of pressure, with Li
ion battery applications and fundamental chemical interest in mind. Using the
ab initio evolutionary algorithm, we predict stability of novel compounds LiO4,
Li5O3 and Li6O under pressure. LiO4, formed at the pressure of just 6 GPa, can
be seen as {\epsilon}-O8 accepting two electrons from two Li atoms. This phase
is superconducting, with Tc up to 12.2 K at 10 GPa. This is remarkable, because
elemental oxygen becomes superconducting at much higher pressure (96 GPa) and
has much lower Tc (<0.6 K), and suggests that chemical alloying with other
elements has the potential of not only decreasing metallization pressure, but
also of increasing Tc. Since {\epsilon}-O8 is called red oxygen, LiO4 can be
identified "lithium red-oxid", and is distinct from superoxide. Additionally,
Li5O3 is stable at pressures above 70 GPa and can be represented as a hybrid
structure 4Li2O {\cdot} Li2O2, and electride suboxide Li6O is stable above 62
GPa.
