| The AB3-type hydrogen storage alloys that contain magnesium in the RE-Mg-Ni hydrogen storage alloys, have a lot of AB5-type alloy composition of the CaCu5 structure and AB3-type alloy composition of the PuNi3 structure. The two kinds of alloy composition form composite structure during the synthesis process. The different corrosion potentials of the composite structure and the instability of magnesium in dominant electrolytes easily lead to rapid capacity degradation and high self-discharge rate of the composite hydrogen storage alloys. At the same time, the heat treatment process has a great influence on the composite structure, especially on the quantity and the relationship between phase transition and temperature of the CaCu5 and PuNi3 structure. To the above questions, it is mainly studied the preparation and properties of the composite AB3-type hydrogen storage alloys through excess entropy method, such as lithium-doped method.The La0.7Mg0.3Ni2.8Co0.5 hydrogen storage alloy was selected and treated using Mg-Li masteralloy and its composition through physical dispersion method. The results showed that the addition of Mg-Li masteralloy improved cycle stability and maximal discharge capacity of the hydrogen storage alloy distinctly, but decreased rate discharge ability. On that basis, it was systematically studied the preparation of lithium excess entropy alloys and electrochemical properties through lithium-doped method in molten salt. In addition, it was also studied the composition and electrochemical properties of the AB4.7-type hydrogen storage alloys under different temperatures and different heat treatment times. The results showed that it could increase the discharge capacity, improve charge retention ratio and enhance high-temperature and low-temperature discharge ability as increasing the lithium content. The maximal discharge capacity, charge retention ratio and rate discharge ability of the AB4.7-type hydrogen storage alloys decreased after annealing treatment. |
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