Phase relations and electrochemical properties of alloys

The phase relations and electrochemical properties of the Ca 1 - x Mg x ( Ni 0.9 Al 0.1 ) 2 alloys have been studied. It was found that the single C15 phase and the single C36 phase exist, respectively, in the approximate composition ranges of x = 0 –0.63 and 0.76–1. Between the single-phase regions, the C15 and C36 phases coexist. The hydrogen storage capacity of the C15-type Ca 1 - x Mg x ( Ni 0.9 Al 0.1 ) 2 alloys was lifted with increasing Mg content x. When x = 0.6 , the hydrogen absorption and desorption capacities are 1.33 and 0.8 wt%, respectively. The alloy electrodes do not need activation during electrochemical measurements. The discharge capacity of the Ca 0.4 Mg 0.6 ( Ni 0.9 Al 0.1 ) 2 alloy is 401 mAh/g at a discharge current of 10 mA/g. However, the cyclic stability should be improved significantly.