The electrochemical hydrogen storage properties of Mg_67-xPd_xCo₃₃ (x=1, 3, 5, 7) electrodes with BCC phase

The ternary Mg_67-xPd_xCo₃₃ (x = 1, 3, 5, 7) alloys were prepared and served as anode materials for the Ni-MH battery system. Pd facilitates the formation of a full body-centered cubic (BCC) phase in binary Mg₆₇Co₃₃. All Mg_67-xPd_xCo₃₃ (x = 1, 3, 5, 7) alloys possess BCC structure in nano-crystalline, which were observed by XRD and TEM analyses. In addition, their lattice parameters increase with the augmentation of Pd content. The charge-discharge experiments show that Mg₆₄Pd₃Co₃₃ owns the maximum discharge capacity of 624 mAh g^-1 among Mg_67-xPd_xCo₃₃ (x = 1, 3, 5, 7) electrodes, which was greatly enhanced from our previously studied binary Mg-Co and ternary Mg-Co-Pd electrodes. All electrochemical kinetics e.g. exchange current density, hydrogen atomic diffusion capability were improved by substituting Pd for Mg, which were also relevant with the increment of Pd amount in the alloys. X-ray photoelectric spectroscopy (XPS) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) demonstrated that Pd relieved the severe corrosions and capacity degradations of the electrodes.