Effect of TiMn1.5 alloying on the structure, hydrogen storage properties and electrochemical properties of LaNi3.8Co1.1Mn0.1 hydrogen storage alloys

Abstract

A series of experiments were performed to investigate the effect of TiMn1.5 alloying on the structure, hydrogen storage properties and electrochemical properties of LaNi3.8Co1.1Mn0.1 hydrogen storage alloys at 303 K. For simple, A, B, and C are used to represent alloys (x = 0 wt %, x = 4 wt % and x = 8 wt %) respectively. The results of XRD and SEM show that LaNi3.8Co1.1Mn0.1−xTiMn1.5 hydrogen storage alloys have LaNi5 phase and (NiCo)3Ti phase. Based on the results of PCT curves, the hydrogen storage capacities of LaNi3.8Co1.1Mn0.1−xTiMn1.5 hydrogen storage alloys are about 1.28 wt % (A), 1.16 wt % (B) and 1.01 wt % (C) at 303 K. And the released pressure platform and the pressure hysteresis decrease with the increase of TiMn1.5 content. Meanwhile the activation curves show that LaNi3.8Co1.1Mn0.1−xTiMn1.5 hydrogen storage alloy electrodes can be activated in three times and the maximum discharge capacity is 343.74 mA h/g at 303 K. In addition, with the increase of TiMn1.5 content, the cyclic stability of the hydrogen storage alloy electrodes decreases obviously and the capacity retention decreases from 76.70% to 70.00% when TiMn1.5 content increases from A to C. It also can be seen that LaNi3.8Co1.1Mn0.1−xTiMn1.5 hydrogen storage alloy electrode C and B have the best self-discharge ability and the best high-rate discharge ability from self-discharge curves and high-rate discharge curves.