  In this letter, we report the discovery of superconductivity in Li3Ca2C6.
Several graphite intercalation compounds (GICs) with electron donors, are well
known as superconductors. It is probably not astonishing, since it is generally
admitted that low dimensionality promotes high superconducting transition
temperatures. Superconductivity is lacking in pristine graphite, but after
charging the graphene planes by intercalation, its electronic properties change
considerably and superconducting behaviour can appear. Li3Ca2C6 is a ternary
GIC, for which the intercalated sheets are very thick and poly-layered (five
lithium layers and two calcium ones). It contains a great amount of metal (five
metallic atoms for six carbon ones). Its critical temperature of 11.15 K is
very close to that of CaC6 GIC (11.5 K). Both CaC6 and Li3Ca2C6 GICs possess
currently the highest transition temperatures among all the GICs.
