3.2. Long-time annealing of Li2C2 with graphite
According to the XRD scans in Fig. 3, the phases in the sample
after annealing at 330 C for 500 h (black line) are the same as directly
after the sample preparation (grey line), i.e. graphite and
Li2C2. Reflexes of LiC6 or other intercalation compounds are not observed,
confirming that no transformation to intercalation compounds
occurred during the annealing time. In both scans there
are peaks with low intensity at 2h angles of 35.7 and 52.9. The reflex
positions of these low intensity peaks match with those of
Al2O3, which is a consequence of abrasion during the preparation
of the powder samples using mortar and pestle.
The XRD scans in Fig. 3 demonstrate clearly that no Lithium
intercalation compounds have been formed during annealing of
Li2C2 and graphite at 330 C in a molar fraction according to the
stoichiometry of LiC6. The mixture of the Li2C2 and graphite is thermodynamically
stable at 330 C whereas LiC6 is not, as shown in
the following.