Effects of the mass ratio of carbonyl nickel powders to Mm0.3Ml0.7Ni3.55Co0.75Mn0.4Al0.3 alloy powders on the electrochemical properties of metal hydride electrodes

Abstract In this work, the carbonyl nickel powders as conductive materials were mechanically mixed with the Mm 0.3 Ml 0.7 Ni 3.55 Co 0.75 Mn 0.4 Al 0.3 alloy powders at different mass ratios. The negative electrodes of the nickel-metal hydride (Ni-MH) rechargeable batteries were prepared. The activation performance, maximum discharge capacity, high rate dischargeability and discharge potential characteristic of the electrodes with different mass ratios have been measured by electrochemical method. The effects of the mass ratio on the electrochemical properties of the electrodes were investigated. The results show that the electrode with 3:1 mass ratio of carbonyl nickel to alloy exhibits the best activation performance, maximum discharge capacity and discharge potential characteristic as well as better high rate dischargeability. The improvements of the electrochemical properties are attributed to the increase of the charge-transfer reaction rate on the alloy surface and the decrease of the internal resistance of the electrodes.