La_(1.8)Ca_(0.2)Mg_(14)Ni_3合金在甲苯溶液中球磨改性后的储氢性能

Hydrogen Storage Properties of La_(1.8)Ca_(0.2)Mg_(14)Ni_3 Alloy Modified by Ball Milling in Toluene

采用在甲苯介质中球磨以改善La1.8Ca0.2Mg14Ni3的储氢性能。随着球磨时间的增加,合金的吸放氢性能得到显著地提高,在20 h达到最高。其在513 K,4.0 MPa氢压下初次活化时,吸氢质量分数达到了3.95%,在3次活化后,300 K时的吸氢质量分数达到3.85%,在613 K,一个大气压的放氢质量分数在900 s内达到了4.92%。通过XRD和SEM分析,球磨后合金颗粒粒径明显减小且有非晶化趋势。在球磨过程中形成了电子络合体(electrondonor-acceptor,EDA)体系。合金颗粒粒径、非晶化程度和EDA共同作用使球磨20 h的合金表现出最优异的吸放氢性能。

The hydrogen storage alloy of La1.8Ca0.2Mg14Ni3 is modified by ball-milling in the toluene to enhance its hydriding/dehydriding properties.The results show that increasing the milling time the hydriding/dehydriding properties of the alloy is enhanced dramatically,and 20 h-milled alloy show the best properties.In the initial cycle,it can absorb 3.95 wt.% hydrogen at 513 K.Even at room temperature（about 300 K） it can absorb 3.85 wt.% hydrogen after being activated for three times.And at 613 K it can desorb 4.92 wt.% hydrogen within 900 seconds to 0.1 MPa.The XRD and SEM analysis indicates that after milling the particle size of the alloy becomes smaller,and parts of the alloy are amorphized to some extent,which makes the alloys easier to be activated.Furthermore,toluene can modify magnesium-based La1.8Ca0.2Mg14Ni3 alloy by formation of the EDA（electro donor-acceptor） complexes when milling.These factors altogether make the alloy show much better hydrogen storage properties after being modified by ball milling in toluene for 20 h.