Study On The Preparation And Hydrogen Storage Of AB₃ Type Alloys

The activation of the AB5-type commercial hydrogen storage alloys is very easy, but the actual discharge capacity of the AB5-type alloys is too hard to be close to the theoretical discharge capacity because of the CaCu5 phase structure, and it is difficult to solve the high-temperature and low-temperature discharge problem. So the development of the MH/Ni batteries is restricted. However, the AB3-type electrode alloys with higher capacity and lower cost is considered as a promising substitution. It is mainly studied the preparation and electrochemical properties of the AB3-type hydrogen storage alloys in this paper.The La0.65Mg0.23Ni2.9Nd0.12Al0.1 and La0.7Mg0.3Ni2.875Co0.525Mn3.1 alloys were synthesized by induction smelting and heat treatment combined method. The crystal structures of the alloys prepared were investigated by X-ray diffraction and scanning electron microscope. In addition, it was also studied the maximal discharge capacity, cycle life, high rate discharge ability and self-discharge of the alloys, besides, the electrochemical properties of the alloys after heat treatment were compared under the conditions of 1123K and 1173K. The results showed that the electrochemical properties of the alloys under the condition of 1123K were better, the reason might be that magnesium was volatilized seriously as increasing the temperature, so as to influence the electrochemical properties. The effects on the alloys using magnesium and its alloys as additives were tentative studied. The maximal discharge capacity showed that the induction melting effect was the best in the form of Mg-Li. The XRD analyses showed that the alloys mainly consisted of the (La, Mg)Ni3 phase and the (La, Mg)2Ni7 phase.