The Investigation Of RE-Mg Hydrogen Storage Alloy And Its Electrochemical Properties

In this paper, the Ml2Mg]7 type RE-Mg hydrogen storage alloys were investigated, which included melting preparation, mechanical milling, electroless deposition and so on. The phase structure, crystal structure, microstructure and electrochemistry properties of different alloy systems were systematically investigated by means of X-ray diffraction, light and SEM metallographic examination, energy spectrum analysis, electrochemical test method. The results showed that:(1) The MNMgn hydrogen storage alloy can be made by melted-chloride protection method, which had stable structure and homogeneous microstructure and is Th2Nii7 type phase primarily. Little LaMg3 occurred on the alloy matrix and the content of Mg was higher on the crystal boundary.(2) After high-energy milling, Some AB5 type MlNi5 phases occurred in the MhMgn/Ni alloy system; and incidental phase which existed in the original Ml2Mgi7 alloy decreased in the Ml2Mgn/MlNi5 alloy system. No obvious oxides existed in the different alloy systems after high-energy milling procedure.(3) After alka electroless nickel deposition, the surface of MhMgiv alloy showed pod appearance and the alloy particles size became smaller. The main component of the alloy was still Ml2Mg17 and the Ni-P layer occurred on the alloy powder surface after disposal.II!(4) As cast alloy Ml2Mgn showed the small discharge capacity and bad activation property, cycle life was also even low. Ordinary mechanical milling made little effect on electrochemical properties of MUMgp/Ni alloy, while high-energy milling better, which greatly enhanced the discharge capacity and improved the activation property and cycle life. The electrochemical properties of Ml2Mg17/MlNi5 alloy were obvious better than value in theory after high-energy milling procedure.(5) The electrochemical properties of MI2Mg|7 alloy were improved at different degree by No.l and No.2 project alka electroless nickel deposition procedure; the No.l showed higher properties especially. After the No.3 project procedure, however, the alloy showed the very low discharge capacity and very short cycle life.(6) After high-energy milling, the particles size of the MhMgn alloy diminished,which enhanced the discharge current density (i? of electrode reaction, depressed the discharge over-voltage (77,) and enhanced the discharge voltage of the alloy electrode. After alka electroless nickel deposition, the discharge over-voltage( 77,) of the alloy electrode decreased and the discharge voltage of that enhanced.