LiAlH_4/4MgH_2+5%M(M=0,NbSi_2,Ni_2Si,Nb_2O_5)复合材料的制备和储氢性能

Preparation and Hydrogen Storage Performance of Composite Materials of LiAlH_4/4MgH_2+5%M(M=0, NbSi_2, Ni_2Si, Nb_2O_5)

应用机械合金化技术制备LiAlH_4/4MgH_2以及LiAlH_4/4MgH_2+5%M(质量分数,M=NbSi_2,Ni_2Si,Nb_2O_5)复合材料,并对其组织、热性质以及吸放氢动力学进行了表征。结果表明,添加NbSi_2、Ni_2Si和Nb_2O_5能提高复合材料的吸放氢动力学性能和改善热力学性质。添加NbSi_2、Ni_2Si和Nb_2O_5使复合材料的氢化反应低温段的峰值温度分别降低了19 K、15 K和23 K,使复合物放氢反应的表观活化能从145.71 k J/mol分别降低到142.12 k J/mol和115.12 k J/mol。

Composite materials of LiAlH_4/4MgH_2＋5%（mass fraction） M（M = NbSi_2, Ni_2Si and Nb_2O_5 respectively） were prepared by mechanical alloying in hydrogen atmosphere, and the hydrogen storage properties of the composite materials, as well as LiAlH_4 and MgH_2 were investigated. The results show that the kinetics property and thermodynamic property of the 4MgH_2/TiH_2 can be improved by adding NbSi_2, Ni_2Si and Nb_2O_5 respectively. DTA curves（by a heating rate 5 K/min） show that the peak temperature within the low temperature range of the hydrogenation for the corresponding composite materials decreased by 19 K, 15 K and 23 K respectively, especially the catalyst effect of which become more obvious after adding Ni_2Si and Nb_2O_5. The activation energy of the LiAlH_4/4MgH_2 composite is 145.71 k J/mol,however, after adding Ni_2Si and Nb_2O_5,which decreases to 142.12 k J/mol and 115.12 k J/mol respectively.