UTILITY TEST ON PROLONGING LIFE TIME OF HYDRIDE BATTERY WITH NANO-CRYSTALLIZED RARE-EARTH JYDROGEN ABSORBING ALLOYS

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The purpose of the present studies is to obtain amorphous or nano-crystallized LaNi_5 phases for prolonging the life time of presently used Ni-hydrides batteries.(1) Development alloys with microstructures consisted of LaNi_5 phases embedded in amorphous phases :The present study successfully prepares the amorphous phase in large compositional range of La-Ni-B systems by melt-spinning. The temperature that LaNi_5 phase is formed is about 500ﾟC in the composition of (LaNi_5)_<0.8-0.7> (LaNi_<12>B_6)_<0.2-0.3>. The PCT measurements reveal that the amount of absorbed hydorgen in amorphous phase is small, that of crystallized alloys after heat-treatment increases and is around 0.9mass%.(2) Amorphous-formation on La-Ni-B alloys with low B content and its hydrogen absorbing properties :The formation of amorphous phase in the alloys with low B content is studied for the compositional alloys of LaNi_3B_<0.5>M_<0.5>(20at%La-10at%B), LaNi_<3.25>B_<0.25>M_<0.5>(20at%La-5at%B), LaNi_<4.85>B_<0.3>M_<0.5>(15at%La-4.5at%B). Then only LaNi_3B_<0.5>M_<0.5> alloy forms the amorphous phase, which absorbs the hydrogen of 0.6mass%. The rest of alloys such as LaNi_<3.25>B_<0.25>M_<0.5> consists of nearly LaNi_5 single phase, which becomes amorphous phase after absorbing hydrogen. But, LaN_<14.85>B_<0.3>M_<0.5> alloys absorb the hydrogen of around 1 mass% at 2MPa hydrogen pressure for all additional elements. After 30 hydride-dehydride cycle test, these crystallized alloys shows almost no degradation in comparison with LaNi_5 alloys, specially the alloy with Fe addition shows the prevention of pulverization of alloys.