A study on ZrCrNiPt_x alloys as negative electrode components for NiMH batteries

摘要

The effect of the addition of Pt on the electrochemical characteristics of AB_2 type ZrCrNi alloys as negative electrode materials for nickel-metal-hydride (Ni-MH) batteries is studied. Electrochemical characteristics of the alloys like as discharge capacity, activation behavior, high rate dischargeability (HRD) and electrochemical impedance spectroscopy (EIS) were analyzed. The resulting ZrCrNiPt_x alloys (x = 0.05 and 0.1 corresponding to 5 wt. % and 10 wt. % respectively) retain the crystalline structure related to hexagonal C14 Laves phases, on both as-melted and annealed samples. Alloy samples containing Pt are found to have a similar activation behavior to the as-melted alloy without Pt. However, this characteristic is improved in annealed samples containing Pt. The discharge capacity of the ZrCrNiPt_x alloys is higher than the discharge capacity corresponding to ZrCrNi alloys, except in the case of as-melted ZrCrNiPto.i alloy. The addition of Pt also improves significantly the high rate dischargeability, maintaining the capacity values in a wide range of discharge current.