The reaction process of hydrogen absorption and desorption on the nanocomposite of hydrogenated graphite and lithium hydride

The lithium-carbon-hydrogen (Li-C-H) system is composed of hydrogenated nanostructural graphite (CnanoHx) and lithium hydride (LiH). CnanoHx is synthesized by ball-milling of graphite under a hydrogen atmosphere. In this work, the reaction process of hydrogen absorption and desorption on the Li-C-H system is investigated. The CnanoHx-LiH composite can desorb about 5.0 mass% of hydrogen at 350 deg. C with the formation of Li2C2 until the second cycle. However, the hydrogen desorption amount significantly decreases from the third cycle. Furthermore, it is shown by using gas chromatography that a considerable amount of hydrocarbons is desorbed during the rehydrogenation process. These results indicate that the amount of reaction between the polarized C-H groups in CnanoHx and LiH is reduced due to a decrease in the C-H groups by losing carbon atoms under the hydrogen absorption and desorption cycles.