Clarifying the polyaniline effect on superior electrochemical performances of hydrogen storage alloys

Abstract Nanoparticle-shaped polyaniline (PANI) is coated uniformly on the surface of hydrogen storage alloys (HSAs) by in situ polymerization of aniline using an electroless method. PANI has a strong attractive interaction with hydrogen during electrochemical reactions, which has been validated by the density functional theory simulations. Moreover, it is easy to form a nickel-rich layer on HSAs surface with the presence of acid during the fast polymerization process of aniline, which is beneficial for the enhancement of electrochemical reaction kinetics. Both of which contribute to the excellent electrochemical performances of the composite of HSAs/PANI as a negative electrode material in nickel-metal hydride (Ni-MH) battery. Compared with the bare HSAs electrode, the maximum discharge capacity of the HSAs/PANI electrode increases from 302.6 to 330.8 mAh g−1 and the capacity retentions enhances from 13.5 to 30.9% at a discharge current density of 3000 mA g−1. The extended systems of HSAs/Ni-doped PANI and HSAs/graphene/PANI composites also show improved high-rate dischargeability properties.