Structure and electrochemical characteristics of LaNi 5-Ti 0.10Zr 0.16V 0.34Cr 0.10Ni 0.30 composite alloy electrode

Abstract

Composite LaNi 5+ x wt.% Ti 0.10Zr 0.16V 0.34Cr 0.10Ni 0.30 ( x=0, 1, 5, 10) alloys were prepared by two-step re-melting. X-ray diffractometer (XRD), scanning electron microscopy (FESEM), energy dispersive spectrometry (EDS), inductively coupled plasma (ICP) and electrochemical impedance spectroscopy (EIS) analyses showed that the matrix phase of LaNi 5 alloy with CaCu 5 structure remained unchanged after additive alloy was added, the amount of the second phase increased with increasing x. The synergetic effect within constituent alloys appeared during the composite process. The electrochemical characteristics of the composite alloy electrodes were greatly improved, and the optimum composition was x=5, at which the low temperature dischargeability at 233 K was 87.37 %, and the maximum discharge capacity and the high rate dischargeability at discharge current density of 1800 mA/g were 326.1 mAh/g and 71.98 % at 303 K, respectively. The HRD was controlled by both the charge-transfer reaction of hydrogen on the electrode/electrolyte interface and hydrogen diffusion coefficient in the bulk of the alloys at discharge current density of 1800 mA/g.