ON THE POSSIBILITY OF HYDROGEN INTERCALATION OF GRAPHITE-LIKE CARBON MATERIALS - ELECTROCHEMICAL AND MOLECULAR-ORBITAL STUDIES

Graphite-like carbon materials were investigated to learn whether they form hydrogen-graphite intercalation compounds (H-GICs), which would be useful as hydrogen storage materials in rechargeable batteries. The ability of graphite-like materials to absorb hydrogen was examined wi th cyclic voltammetry (CV) and constant-current charge and discharge t ests in 6 mol dm(-3) KOH. It was concluded that H-GICs did not form un der our experimental conditions. In order to understand the difference between hydrogen and lithium ions in ability to form the intercalatio n compounds with graphite-like carbon materials, molecular orbital ana lyses were carried out. The results demonstrate that lithium-graphite intercalation compounds (Li-GICs) are stable because of the presence o f lithium 2p-orbitals, whereas such stable graphite intercalation comp ounds do not form with hydrogen ions because no three-dimensional p-or bitals are available.