Preparation Of Amorphous Mg-Ni Based Hydrogen Storage Alloy And Investigation On Its Properties

The Mg-based hydrogen storage alloys have many advantages, such as large hydrogen capacity, low density, high storage volume, low price, and so on. They were considered as one of the most promising hydrogen storage materials. But its high temperature and low speed of absorbing and desorbing hydrogen limited its practical application. Making crystal Mg-based alloys into amorphous alloys can possibly improve its dynamic properties and reduce its temperature of absorbing and desorbing hydrogen. However, when applied to be the negative electrode of secondary battery, amorphous Mg-based alloys'cycle stability was too weak to be used practically. How to solve these problems is the focus of the research on it.In this paper, amorphous Mg-Ni binary alloys and amorphous Mg-Al-Ni and Mg-Ti-Ni ternary alloys were prepared successfully by mechanical alloying. XRD, SEM, pressure composition temperature (PCT) measurement and electrochemical properties test were employed to analyze the properties of the alloys and the results showed that:①Using mechanical alloying, when the rotational speed and the mass ratio of steel balls to elemental powder were both large enough, that is to say, when sufficient energy was brought in, amorphous Mg-Ni alloys can be prepared by ball-milled for a certain time. Nanocrystal alloys or composite of nanocrystal and amorphous alloys can be prepared by shortening the ball-milling time. After making crystal Mg-Ni alloys into amorphous alloys, they absorbed hydrogen without activation and their dynamic properties were clearly improved. Especially, the temperature of absorbing and desorbing hydrogen was evidently decreased. For amorphous MgNi binary alloy, the lowest temperature of absorbing and desorbing hydrogen was only 70℃. The formation and properties of amorphous Mg-Ni alloys were influenced by both the ball-milling parameters and content of Ni.②Although adding Al and Ti into Mg-Ni alloys would decrease the forming ability of amorphous phase, amorphous Mg1-xAlxNi(x=0.1 , 0.2 , 0.3) and Mg1-xTixNi(x=0.1,0.2,0.3) ternary alloys can also be prepared by mechanical alloying. The adding of Al and Ti greatly improved the alloys'cycle stability. After 10 charge and discharge cycles, Mg0.8Al0.2Ni and Mg0.9Ti0.1Ni still remained 80.1% and 79.1% of its maximal discharge capacity respectively. But the adding of Al decreased the discharge capacity of the alloys while Ti had little negative influence. Especially, the maximal discharge capacity of Mg0.9Ti0.1Ni reached 206.2mAh/g.To sum up, in this paper, through making crystal Mg-Ni alloys into amorphous alloys,the dynamic property was improved and the temperature of absorbing and desorbing hydrogen was reduced. Through adding Al and Ti into Mg-Ni alloys to prepare amorphous ternary alloys, the cycle stability was improved.