Electrochemical performance of hydrogen storage alloy MlNi(3.65)Co(0.75)Mn(0.4)Al(0.2) with various particle sizes

The effects of particle size on the electrochemical property of MlNi(3.65)C o(0.75)Mn(0.4)Al(0.2) have been systematically investigated. The results at charge/discharge current of 200 mA g(-1) showed that the smaller the parti cle size, the larger is the first discharge capacity and the earlier is the saturation capacity reached, however, the saturation discharge capacity in creases with the increase in particle size. The particle size dependence of high-rate dischargeability is similar to that of the saturation discharge capacity when the discharge current is less than 600 mA g(-1),but it change s at 600 mA g(-1) or more; the higher the discharge current, the more obvio usly the particle size affects the property of the alloy. The cycle life te st at 300 mA g(-1) showed that the discharge capacity in all 400 cycles inc reases with the increase of particle size, and the discharge capacity decay rate is almost the same except that the rate for 25.5 um particles is slig htly faster. (C) 2001 International Association for Hydrogen Energy. Publis hed by Elsevier Science Ltd. All rights reserved.