Effects of amorphous NiB on electrochemical characteristics of MgNi alloy

Amorphous NiB was prepared by chemical reduction method. The effects of NiB on the electrochemical properties of MgNi alloy were investigated. MgNi-NiB composite was prepared by mechanical alloying (MA). The MgNi-NiB (weight ratio 100:10) composite which was MA 15 h exhibited the best performance. After 50 charge-discharge cycles, the specific discharge capacity was still above 210 nAh g(-1) and the capacity retention was 50.15%, which was much higher than that of MgNi (no more than 10%). The exchange current density I-0 increased with the increasing of NiB (from 67.60 to 344.80 mAg(-1)) which indicated that NiB improved the electrochemical kinetics of the hydrogenation/dehydrogenation of MgNi alloy in alkaline solutions. Potentiodynamic polarization results showed that the corrosion voltage (E-corr) got a positive shift from -0.933 to -0.879 V and corrosion current density was decrease from 4.69E-4A to 1.24E-5A, which indicated that the larger corrosion resistance of MgNi values of whole ohmic resistance (R-o) and charge transfer resistance (R-t) of the MgNi-NiB alloy were reduced by NiB comparing with MgNi. In conclusion, NiB improved the electrochemical characteristics of the MgNi alloy significantly. (C) 2008 Elsevier B.V. All rights reserved.