| RE-based AB5-type hydrogen storage alloys, as the main negative electrode materials of commercial Ni/MH batteries, aren't very satisfied in some electrochemical characteristics, such as initial activation property, high rate discharge capability and discharge capacity at lower temperature, which are closely related to the electrocatalysis activity, corrosion-resistance ability and conductibility of MH electrode's surface. Therefore, it is meaningful for both in theory and in practice to research some simple and effective surface modification methods to treat with RE-based AB5-type hydrogen storage alloys, aimed at improving the electrochemistry performances of Ni/MH battery.In this paper, it has been studied that RE-based AB5-type hydrogen storage alloys were treated with surface duplicated modification solution by added M2+(M=Ni, Co, Cu) and reductive agent (NaH2PO2) into HF-KF solution or organic acid, so that fluorination or organic acid treatment and micro- encapsulation were carried out by one step. The phase structure of AB5 alloy wasn't changed after the modification, the oxide was removed and a Ni-richer layer was formed on the surface, and AB5 alloy was microencapsulated with Ni, Co, and Cu coatings by the duplicated modification. It has been found that not only the initial activation behavior and high rate dischargeability of the alloy electrodes were improved by fluori-duplicated surface modification, but also the discharge capacity was increased from 67 mAh/g to 200 mAh/g at 238 K. The discharge voltage platform at big current density of the electrodes modified by organic-duplicated method were prolonged and heightened, and the discharge capacity at lower temperature was also greatly improved. At the same time, the AB5-type alloys was modified with alkaline-duplicated method by added NaH2PO2,N2H4·H2O and NaBH4 into the alkaline solution, initial discharge capacity of the electrodes were increased significantly and intermediate discharge voltage has been increased.
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