B/C/N graphite-like structure: determination of the chemical composition and intercalation of metals in lithium-based alloys.

摘要

Among carbon-based materials, B/C/N compounds appear as very interesting graphite-like host structures. Indeed, as graphite, the weak bonding between B/C/N layers allows intercalation reactions. Currently, alkali metals are mainly intercalated in vapor phase or by electrochemical way [1]. The solid-liquid method in alkali metal-based alloys developed for the intercalation of numerous metals into graphite has been adapted for B/C/N materials. Indeed, this chemical way of intercalation into B/C/N could be very useful since alkali metals intercalate easily into B/C/N and are then able to play the role of an intercalation vector. In the case of graphite, lithium appeared as a good intercalation vector for various elements such as alkaline-earth or lanthanides metals [2]. On one hand, it allows to considerably reduce the reaction temperature in order to avoid the parasitic formation of carbides by serving as a flux for its alloyed metal. On another hand, it makes easier the intercalation of the second metal by pre-opening the graphitic galleries, leading to binary or ternary compounds. In this study, B/C/N graphite-like layered materials have been prepared by CVD reaction and used as host lattice for intercalation of lithium-based metallic alloys. So, solid-liquid reactions in lithium- calcium alloys have been performed for the first time to co-intercalate lithium and calcium into B/C/N materials. Ion beam analysis using nuclear microprobe with a proton beam allowed to determine the chemical composition of both pristine and intercalated materials.