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 °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