Simultaneous intercalation of lithium, potassium and strontium into graphite in molten salts medium

Abstract

The LiCl–KCl molten salts method has been used in order to intercalate strontium into graphite. Combination of X-Ray Diffraction (XRD) experiments and ion beam analyses attests the obtaining of a monophasic sample. Its chemical composition corresponds to the Li0.2K0.6Sr0.4C6 formula, revealing the synthesis of a quaternary Graphite Intercalation Compound (GIC), in agreement with the high repeat distance of 640 pm determined from its 00l XRD and with the 1D electronic density profile. The very high-quality data obtained by hk0 diffraction and rotating crystal method lead to a 2D organization of the intercalated sheet described by a large hexagonal unit cell containing 78 carbon atoms. Such quaternary phase including simultaneously alkali and alkaline-earth metals is unique and can only be prepared from molten salts method, opening new perspectives concerning graphite-based two-dimensional materials.