Improvement of electrochemical properties of Nd-Mg-Ni-based hydrogen storage alloy electrodes by evaporation-polymerization coating of polyaniline

In this study polyaniline (PANI) was coated on Nd-Mg-Ni-based alloy surface via an evaporation-polymerization method. SEM-EDX results show that PANI coats on the alloy particle surface, and remains stable during charging/discharging cycles. With assistance of PANI in improving kinetics, high rate dischargeability at 1500 mA/g increases by 12.7% (The treating time is 45 min). Cyclic voltammogram and infrared tests on charged and discharged electrodes shows that transformation between benzene-quinone oxidation species and benzene-benzene reduction species in the charging/discharging electrochemical windows of metal hydride electrodes helps to improve high rate dischargeability by facilitating charge transfer and subsequent hydrogen diffusion. The PANI not only works as an electro-catalytic layer but also as a protective layer to improve cycling stability of Nd-Mg Ni-based alloy electrodes. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.