Electrochemical characteristics and microstructure of – composite hydrogen storage alloys

AB 2 – x % LaNi 5 ( x = 0 , 1 , 5 , 10 ) composite alloys were prepared by melting Zr 0.9 Ti 0.1 Ni 1.1 Mn 0.6 V 0.3 with a small amount of LaNi 5 alloy as addition. The microstructure and electrochemical characteristics of the composite alloys were investigated by means of XRD, SEM, EDS and electrochemical measurements. It was shown that LaNi 5 addition does not change the basic hexagonal C14 Laves phase of AB 2 alloys, but some second phases have segregated. It was found that the addition of LaNi 5 greatly improves the activation property, high-rate dischargeability (HRD) and charge–discharge cycling stability of AB 2 Laves phase alloy. At current density of 1200 mA/g, HRD of the alloy increases from 38.92% ( x = 0 ) to 60.09% ( x = 10 ). The capacity retention of the alloy after 200 charge–discharge cycles increases from 57.10% ( x = 0 ) to 83.86% ( x = 5 ) and 67.31% ( x = 10 ). The improvement of the electrochemical characteristics caused by LaNi 5 addition seems to be related to formation of the second phases.