Mg-based hydrogen storage alloys MgNi, Mg0.9Ti0.1Ni, and Mg0.9Ti0.06Zr0.04Ni were successfully prepared by means of mechanical alloying （MA）. The structure and the electrochemical characteristics of these Mg-based materials were studied. The X-ray diffraction （XRD） result shows that the main phases of the alloys exhibit amorphous structure. The scanning electron microscopy （SEM） photograph shows that the particle size of Ti and Zr substituted alloys was about 2-4 μm in diameter. The cycle lives of the alloys were prolonged by adding Ti and Zr. After 50 charge-discharge cycles, the discharge capacity of Mg0.9Ti0.06Zr0.04Ni was 91.74% higher than that of MgNi alloy and 37.96% higher than that of Mg0.9Ti0.1Ni alloy. The main reason for the electrode capacity decay is the formation of Mg（OH）2 （product of Mg corrosion） at the surface of alloy. The potentiodynamic polarization result indicates that Ti and Zr doping improves the anticorrosion in an alkaline solution. The electrochemical impedance spectroscopy （EIS） results suggest that proper amount of Ti and Zr doping improves the electrochemical catalytic activity significantly.
Mg-based hydrogen storage alloys MgNi, Mg0.9Ti0.1Ni and Mg0.9Ti0.1Ni0.9Co0.1 were successfully prepared by means of mechanical alloying （MA）. The structure and the electrochemical characteristics of these Mg-based materials were also studied. The results of X-ray diffraction （XRD） and scanning electron microscopy （SEM） show that the main phases of the alloys exhibit amorphous structures, and trace of Ni co-exists. The charge-discharge cycle tests indicate these alloys have good electrochemical active characteristics. And the cycle stability of Ti and Co doped alloy was better than that of MgNi alloy. After 50 cycle charge-discharge, the discharge capacity of the Mg0.9Ti0.1Ni0.9Co0.1 alloy was much better than that of MgNi and Mg0.9Ti0.1Ni alloys. The discharge capacity of Mg0.9Ti0.1Ni0.9Co0.1 was 102.8% higher than that of MgNi alloy, and 45.49% higher than that of the Mg0.9Ti0.1Ni alloy. During the process of charge-discharge cycle test, the main reason for the electrode capacity fading is the corrosion of Mg to Mg（OH）2 on the surface of alloys. The Tafel polarization test indicates Ti and Co improve the anticorrosion in an alkaline solution. The EIS results suggest that proper amount of Ti and Co doping improve the electrochemical catalytical activity on the Mg-based alloy surface significantly.
The structure and electrochemical characteristics of La_(0.7)Mg_(0.3)Ni_(2.875)Co_(0.525)Mn_(0.1)-boron composite was studied systematically.The AB_(3) type hydrogen storage alloys La_(0.7)Mg_(0.3)Ni_(2.875)Co_(0.525)Mn_(0.1) were successfully synthesized by means of inter-media alloy La_(2)Mg_(17).The alloys were composited with boron at different weight rate.From the XRD analyses,each alloy of this series is mainly composed of(La,Mg)Ni_(3) phase and the LaNi_(5) phase,and the phase abundance of each phase varies with the boron weight rate,moreover,after composition,the c and cell volumes of(La,Mg)Ni_(3) phase increase,and the LaNi_(5) phase keep the same,which indicate that the boron may enter(La,Mg)Ni_(3) phase.The electrochemical studies show that the maximum discharge capacity of the composites decreases,but the cycling life improved.And the high rate discharge ability and exchange impendence spectroscopy(EIS)of the AB_(3) alloys and its composite were also studied.
LIU YiWANG YijingXIAO LinglingCAO JianshengJIAO LifangFENG YanYUAN Huatang
The La0.8Mg0.2Ni2.4Mn0.10Co0.55Al0.10 alloy was prepared by induction melting. The structural and morphological characterizations were performed by means of X-ray powder diffraction （XRD） and scanning electron microscopy （SEM）. The electrochemical measurements were performed using LAND and CH/660b electrochemical workstation. The main phases of the alloy were LaNi5 and （La,Mg）Ni3. After annealing, the maximum discharge capacity, cycle stability and high rate dischargeability （HRD） were improved obviously. The maximum discharge capacity reached 373.80 mAh/g （T=1173 K）, the C100/Cmax（%） was 72.63% （T=1173 K）, and the value of HRD reached 51.8% at a discharge current density of 1150 mA/g （T=1173 K）. The cyclic voltammetry （CV） and potentiodynamic polarization were also studied.
