Abstract

The demand for high efficient solid-state hydrogen storage materials for the coming hydrogen economy encourages tremendous efforts in the development of novel systems such as complex chemical hydrides and carbonaceous materials. Lithium nitride, newcomers to the sorbent system, exhibits strong affinity towards hydrogen molecules. 11.5wt% of hydrogen can be absorbed via a two-step reaction with lithium amide (LiNH2) and Lithium hydride (LiH) generated as final products. Surprisingly, mixture of above two materials can desorb hydrogen upon heating to 170oC. Hydrogen can not come from LiH for it’s so stable and its decomposition occurs above 550oC. For LiNH2, it will decompose to Li2NH and NH3 at 360oC. Thus, certain interaction between LiNH2 and LiH should exist and be responsible for hydrogen release at lower temperature. Enlightened from this point we had some other systems compose of alkali metal amide and hydride tested and we found that it’s a common rule and this rule can be guidance for synthesis of hydrogen storage materials.
 

Abstract

In the search for efficient hydrogen storage materials, great attentions have been caught by lithium nitride with its remarkable capacity of H2 storage performance. Mechanism studies show that the lithium amide and imide are the intermediates in the hydrogen absorption / desorption process. Like the approaches used in the metal H2 storage materials, binary, ternary or multiparty nitrides have been reportedly synthesized, which unprecedentedly enlarges and complexes the compound categories of nitrides, imides and amides. Fundamental understandings of these compounds, both in physicochemical properties and chemical structures, will enable the elucidation of the interaction processes between these kinds of materials and hydrogen. Using Differential Scanning Calorimetry (DSC) and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFT), some thermodynamic and kinetic properties and structural properties have been investigated.