Activation Characteristics of Ml_ (1-x)Mm_x(Ni_ ( 3.550Co_ ( 0.750Mn_ (0.4)Al_ ( 0.3)) Hydrogen Storage Alloys After Surface Modification

摘要

The surface of multicomponents Ml_ 1-xMm_x(Ni_ 3.55Co_ 0.75Mn_ 0.4Al_ 0.3)(x=0, 0.1, 0.2, 0.3, 0.4, 0.5) hydrogen storage alloys was impregnated in the vitriol liquor (0.01, 0.02, 0.04 mol·L -1) for five minutes at room temperature. With the following charge/discharge procedure, I_c=60 mAh·g -1×7.5 h, I_d=60 mAh·g -1, the final cutoff voltage was -0.60 V (vs. Hg/HgO), activation characteristics of the alloys with different Ml∶Mm ratio were investigated. And the effects on activation characteristics of alloys modified by different surface methods were also investigated. The results indicate that Ml:Mm ratio and different surface modification process have a prominent effect on activation characteristics of the alloys. Activation characteristics and initial discharge capacities of the alloys have a great improvement after surface modification. The effects of activation characteristics are more obvious with the vitriol concentration increasing. The alloy Ml_ 0.7Mm_ 0.3(Ni_ 3.55Co_ 0.75Mn_ 0.4Al_ 0.3) shows the best activation characteristics and a maximum discharge capacity. With surface modification, the alloy was activated after 2 cycles, and the maximum discharge capacity is 250.1 mAh·g -1.