添加Si对Mg-Li合金储氢性能的影响

Effect of Si addition on hydrogen storage performance of Mg-Li alloy

在氩气保护下,采用热处理并结合机械球磨合金化制备Mg_(90)Li_(10+x)%Si(x=0,2,5,8(质量分数))合金储氢材料,研究Si的添加对Mg-Li合金储氢性能的影响。结果表明:Mg_(90)Li_(10+x)%Si(x=2,5,8)合金材料经过热处理和机械合金化后,Li容易扩散进入Mg晶格体内形成Mg(Li)固溶体,Si与Mg结合生成Mg_2Si,而Mg_2Si不仅能改善Mg-Li合金的吸/放氢动力学性能,而且还能提高Mg-Li合金的热力学性能。Mg_(90)Li_(10+x)%Si(x=0,2,5,8)合金的初始脱氢温度从632 K(x=0)分别下降到了610 K(x=2)、598 K(x=5)和598K(x=8);Mg-Li合金的脱氢表观活化能为396.5kJ/mol,而添加Si后,其分别下降了13.3 k J/mol(x=2)、21.1 kJ/mol(x=5)和67.4kJ/mol(x=8)。

The Mg90Li10＋x%Si（x=2, 5, 8（mass fraction）） alloys hydrogen storage material were synthesized by heat treatment in combination with mechanical milling, and the Si effect on the hydrogen storage properties of Mg-Li alloys were studied. The results show that the Li atom diffuses easily into Mg matrix to Mg（Li） solid solution, and the Si element reacts with Mg element to form Mg2Si. It is clearly that the existence of Mg2Si can improve the hydrogen absorption/desorption kinetic properties and thermodynamic performance for Mg-Li alloys. For example, with the addition of Si, the initial hydrogen desorption temperature for the Mg90Li10＋x%Si alloys decreases from 632 K（x=0） to 610 K（x=2）, 598 K（x=5） and 598 K（x=8）, respectively. The apparent activation energies for the Mg（90）Li（10＋x）%Si（x=2, 5, 8） alloys are 13.3 kJ/mol（x=2）, 21.1 kJ/mol（x=5） and 67.4 kJ/mol（x=8） lower than that of Mg-Li alloy.