Investigation of disproportionation behaviour of LaNi_(5-x) M_x in hydriding process at high temperature

X ray diffraction, thermal and electrochemical analysis were used to investigate the disproportionation behaviour of hydrogen storage alloys for LaNi 5- x M x in hydriding process at high temperature and electrochemical properties of the reaction products. The results showed that the disproportionation took place and the precipitated Nano phase metallic Nickel was formed during an certain period of heat preservation at temperature of 550 ℃ and under the pressure of 2.5 MPa. The extent of the disproportionation reaction was closely related to temperature, heating duration substituted third elements M, and the formation enthalpy of the alloys. Measurement of the exchange current density showed that the contained Nano phase Nickel composite structure obtained by the disproportionation reaction exhibited better electrocatalytic characteristics during hydrogen absorption and desorption than the master alloys.