The electrochemical properties of coke and natural graphite in some el
ectrolyte solutions containing diethylcarbonate (DEC) are studied. It
is found that natural graphite exhibits an excellent performance, such
as high discharge capacity (370 mAh(-1) g), when a mixed solvent comp
osed of ethylene carbonate (EC) and DEC is used. The charge/discharge
characteristics of the coke electrode are not influenced by the specie
s of the electrolyte solution, but those of the natural graphite elect
rode are very much influenced by the species of the electrolyte soluti
on. It is confirmed that there are three patterns in the behaviour of
the graphite electrode in the electrolyte solutions tested in this inv
estigation. In the first pattern, natural graphite can be charged to C
6Li and then discharged. In the second pattern, the charging and disch
arging of the natural graphite electrode is impossible and destruction
of the natural graphite crystal structure is observed. In the third p
attern, lithium is intercalated into the graphite layer but the de-int
ercalation of lithium does not take place.