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

Abstract

The lithium–carbon–hydrogen (Li–C–H) system is composed of hydrogenated nanostructural graphite (C nano H x ) and lithium hydride (LiH). C nano H x 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 C nano H x –LiH composite can desorb about 5.0 mass% of hydrogen at 350 °C with the formation of Li 2 C 2 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 C nano H x and LiH is reduced due to a decrease in the C–H groups by losing carbon atoms under the hydrogen absorption and desorption cycles.