Study On Hydrogen Storage Property Of LiNH₂+MgH₂Complex Hydride

LiNH2+MgH2hydride, high hydrogen storage capacity and good thermodynamic performance, is a kind of promising hydrogen storage material. In the experiment, the performances of LiNH2+MgH2hydride, synthesized from LiNH2and MgH2by the means of machannical ball-milling, was analyzed with the methods of XRD, absorption and desorption hydrogen performance test, thermal analysis and infrared spectral analysis. This paper mainly discussed the effect of the ball-milling time and environment, catalyst and the the amount of catalyst on hydrogen storage performance of LiNH2+MgH2hydride.The experiments found that after nine hours ball-milling, during which LiNH2and MgH2could react completely, the temperature of LiNH2+MgH2on hydrogen absorption/desorption was lower; the content of hydrogen absorption/desorption was large; and the reversibility of hydrogen absorption/desorption and thermodynamic performance was good. By mechanical ball-milling, in the environment of high pressure high purity hydrogen compared to the environment of full fill of argon, LiNH2+MgH2reaction activation energy of hydrogen desorption was decreased and thereby the temperature of hydrogen desorption was reduced.The catalyst, including Ti, especially TiF3, can effectively improve LiNH2+MgH2performance on hydrogen absorption/desorption, and reduce the temperature of hydrogen absorption/desorption.The studies indicated that,the action of LiNH2+MgH2was catalyzed sufficiently by the addition of5wt.%TiF3,which also expedited the generation of Mg(NH2)2, and effectively reduced the temperature of hydrogen absorption/desorption. According to the test, after added5wt.%TiF3, the initial temperature of hydrogen desorption was reduced38℃; the optimum temperature range in desorption and absorption was reduced30℃and23℃respectively.The addition of magnalium solid solution will reduce the hydrogen storage capacity of LiNH2+MgH2, but it is contributed to the generation of MgNH, and the hydrogen desorption. With the addition of5wt.%magnesium solid solution, both the initial temperature and the temperature of heterothermy dehydrogenation dropped slightly, but the content of dehydrogenation increased.