HYDROGEN-ABSORBING ALLOYS FOR THE NICKEL-METAL HYDRIDE BATTERY

In recent years, owing to the rapid development of portable electronic and electrical appliances, the market for rechargeable batteries has increased at a high rare. The nickel-metal hydride battery (Ni/MH) is one of the more promising types, because of its high capacity, high-ra te charge/discharge capability and non-polluting nature. This type of battery uses a hydrogen storage alloy as its negative electrode. The c haracteristics of the Ni/MH battery, including discharge voltage, high -rate discharge capability and charge/discharge cycle lifetime are mai nly determined by the construction of the negative electrode and the c omposition of the hydrogen-absorbing alloy. The negative electrode of the Ni/MH battery described in this paper was made from a mixture of h ydrogen-absorbing alloy, nickel powder and polytetrafluoroethylene (PT FE). A multicomponent MmNi(5)-based alloy (Mm(0.95)Ti(0.05)Ni(3.85) Co 0.45Mn0.35Al0.35) was used as the hydrogen-absorbing alloy. The discha rge characteristics of the negative electrode, including discharge cap acity, cycle lifetime, and polarization overpotential, were studied by means of electrochemical experiments and analysis. The decay of the d ischarge capacity for the Ni/MH battery (AA sie, 1 Ah) was about 1% af ter 100 charge/discharge cycles and 10% after 500 charge/discharge cyc les, (C) 1998 International Association for Hydrogen Energy.