Effects of additions on AB_5-type hydrogen storage alloy in MH-Ni battery application

摘要

The AB_5-type hydrogen storage alloy of Mm_(0.3)Ml_(0.7)Ni_(3.55)Co_(0.75)Mn_(0.4)Al_(0.3) were synthesized and mixed with PVA (Polyvinyl Alcohol) or different percentage Ni powder as the test samples. The cycle stabilities of the composites were tested in 6 M KOH electrolyte through electrochemical method. The results indicated that all the samples with Ni powder have better cycle stabilities and flatter discharge voltage platform. The sample of Mm_(0.3)Ml_(0.7)Ni_(3.55)Go_(0.7)5Mn_(0.4)Al_(0.3) + 200 wt.% Ni has the highest capacity conservation rate of 80.5% and the longest discharge time of 5.2 h. The SEM images show that the particle diameters of the alloy decreased by 2 μm and the surface smoothed without sharp edges after adding Ni powder. It can be presumed that adding Ni can improve the cycle stability of the alloy of Mm_(0.3)Ml_(0.7)Ni_(3.55)Go_(0.7)5Mn_(0.4)Al_(0.3) in the alkaline electrolyte and enhance the reaction rate in the charge/discharge cycles.