Several authors applied DTA or differential scanning calorimetry
(DSC) to study pure LiC6. There is general agreement that lithium
graphite intercalation compounds transform irreversibly to
Li2C2 and graphite at ‘‘high temperatures’’ [8,17,18]. However,
there is no consensus about the exact specification of the temperature
above which the transformation will occur. On the one hand
the transformation was not observed at temperatures up to 600 C,
and only thermal cycling with temperatures up to 727 C resulted
in a stepwise de-intercalation of LiC6 and the formation of Li2C2
[8,18]. It was further reported that a very weak DTA signal is associated
with the Li2C2 formation [18]. On the other hand it was stated
that LiC6 transforms to Li2C2 above 477 C [17]. In this case LiC6
was annealed with an excess of Li that is considered to lead to a
reduction of the transformation temperature of LiC6 to Li2C2 [18].