Low cobalt content alloy for Ni-MH battery electrodes

摘要

Most of negative electrodes in rechargeable Nickel-Metal Hydride batteries contain an AB(5) type alloy. A new non-stoichiometric A(0.95)B(4.8) type alloy, prepared by arc-melting, is presented. It is a low Co alloy Lm(0.95)Ni(3.8)Co(0.3)Mn(0.3)Al(0.4) (Lm: La-rich mischmetal) which is studied in order to reduce costs in technological applications. Negative electrodes prepared with alloy particles of different sizes are electrochemically cycled, reaching the maximum discharge capacity of 322.2 mAh.g(-1) for initial particle sizes between 37 and 74,mu m. For cycling stability, after 60 electrochemical cycles, capacity decay is 7.8%. Rate capability and self-discharge tests of the electrodes are performed showing good performance.