Synthesis of ternary and quaternary graphite intercalation compounds containing alkali metal cations and diamines

A series of ternary graphite intercalation compounds (GICs) of alkali metal cations (M = Li, Na, K) and diamines [EN (ethylenediamine), 12DAP (1,2-diaminopropane), and DMEDA (N,N-dimethylethylenediamine)] are reported. These include stage 1 and 2 M-EN-GIC (M = Li, d_i = 0.68-0.84 nm; M = Na, d_i = 0.68 nm), stage 2 Li-12DAP-GIC (d_i = 0.83 nm), and stage 1 and 2 Li-DMEDA-GIC (d_i = 0.91 nm), where d_i is the gallery height. For M = Li, a perpendicular-to-parallel transition of EN is observed upon evacuation, whereas for M = Na, the EN remains in parallel orientation. Li-12DAP-GIC and Li-DMEDA-GIC contain chelated Li⁺ and do not show the perpendicular-to-parallel transition. We also report the quaternary compounds of mixed cations (Li,Na)-12DAP-GIC and mixed amines Na-(EN,12DAP)-GIC, with d_i values in both cases between those of the ternary end members. (Li,Na)-12DAP-GIC is a solid solution with lattice dimensions dependent on composition, whereas for Na-(EN,12DAP)-GIC, the lattice dimension does not vary with amine content.