RAPIDLY QUENCHED NI64ZR36 FIBER ANODES FOR NI/HYDRIDE RECHARGEABLE BATTERIES

The potentialities of rapidly quenched alloy fibers as anodes in rechargeable Ni/hydride batteries have been investigated. Data are presented on a series of rechargeable batteries constructed using anodes manufactured from Ni64Zr36 fibers, obtained by a melt extraction procedure. Charge capacities were found to be in the range from 220 to 260 mAh/g, which is higher than has been reported for electrodes of amorphous ribbons of the same composition. The dependence of the charge capacity on the charge/discharge rates is discussed in terms of the kinetics of the reduction/oxidation process at the amorphous alloy surface. The decrease of coulombic efficiency with increasing supplied charge is found to parallel that of the open-circuit potential of the anode. The decrease of charge retention with storage time under open-circuit conditions is found to follow the change of the stationary potential of the electrode. Both trends are discussed in terms of the release of hydrogen atoms from the different types of sites in the metallic glass. The performances of the electrode are discussed in terms of the characteristics of hydrogen desorption from cylinder hosts, as well as of the composite nature of the fibers, a predominantly amorphous structure, with a small content of crystalline phase.