Crystal structure and electrochemical performance of Lao.75Ce0.25Ni3.46- Al0.17Mn0.04Co1.33 alloy for high-power-type 29 Ah Ni-MH battery

An AB5 type alloy, La0.75Ce0.25Ni3.46A10.17Mn0.04COl.33, was successfully prepared via partial substitution of Ce for La and A1, Mn, Co for Ni, respectively. The structure, morphology, and chemical composition of the as-obtained alloy powders were care- fully examined by X-ray diffraction, scanning electron microscopy equipped with energy dispersive X-ray spectroscopy. Electro- chemical properties of the hydrogen storage alloy were systematically investigated in standard 29 Ah Ni-MH batteries. The 29 Ah Ni-MH battery exhibited a theoretical discharge capacity of 29 Ah at 1 C. The capacity retention was 99% after 2000 cycles. Fur- thermore, excellent low temperature performance of this hydrogen storage alloy was obtained at -25 ~C. And the results showed that it exhibited not only high discharge capacity （21 Ah at -25 ~C and 1 C）, excellent high current densities instantaneous discharge performance （discharge 0.9 Ah in 10 s at 12.5 C rate and the voltage could be maintained around 0.73 V）, but also remarkable high-rate discharge capacity （discharge 17.7 Ah at 50% SOC and 6.25 C, and the voltage could be maintained around 0.95 V）.