LaNis-based alloys

Much of this study was conducted on LaNij-based alloys [13-20] and TiNi -based alloys [21-23]. Sanyo Electric, Matsushita Battery and most other battery manufacturers have been using LaNi,-based rare earth-nickel-type alloys [24,... 

Stoichiometry in LaNis-based metal hydride alloys... 

The Aoki group [218] has been developing intermetallic alloys based on a CaSi compound that is alloyed with Si, Al, Ge, Mg, and Sr. However, the alloys cannot compete with the LaNi -type or even TiFe because they absorb only slightly more than 2 wt.%H at 100°C and desorb at 200°C. 

There is sensitive La in the alloys based on intermetallic compound LaNi 5. If discussing production of large quantities of the said materials by metal component... 

New, high-density nickel oxide electrode materials, coupled with nonwoven nickel-fiber current collectors, have significantly improved the performance of the nickel electrode even in the nickel-cadmium cells [5j. The alloys used to form hydride, which capture and release hydrogen in volumes up to nearly a thousand times their own, include rare-earth/nickel alloys (generally based on LaNis and called AB5)... 

This chapter summarizes important contributions on the AB5/AB and elemental hydrides. Examples of microalloying in LaNis- and FeTi-based intermetallic hydrides have been emphasized, and there has been some discussion on elemental hydrides. Classification of testing methods for durability of alloys/ intermetallics were presented, examples of intrinsic and extrinsic tests that include cycling and aging have been reported for AB5/AB and other alloys. More recent results on extrinsic tests on lightweight complex hydrides (imide-amide) that were cycled between Li2NH/LiNH2 phases were also reported. 

Two types of metallic alloys are used a) rare-earth (misch metal) alloys, known as AB5, based on lanthanum and nickel (LaNis plus some substituents) b) alloys based on titanium and nickel, plus V, Zr, Cr, known as AB2. The first type is the most widely used. A hydrogen-absorbing alloy must allow quantitative absorption-desorption at relatively high rates and for hundreds of cycles. 

Laboratories around the world have exhausted nearly all the elements in the periodic table to synthesise various AB2 and AB5 alloys to improve the cycle life and capacity of metal hydride cells. The major problem with metal hydride electrodes is that the function of the alloying elements either pristine or in combination with other alloying elements cannot be predicted with certainty. Conventional AB5 and AB2 alloys based on LaNis and (Ti, Zr)Ni2 have relatively low coulombic capacity values between 300 and 450 Ah/kg. Present research has focused on alloys such as TiZrNi2 and Mg2Ni as low-cost, lightweight and safer electrode alternatives, thereby increasing the energy density of the Ni-MH battery. 

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