Hydrogen storage alloys, hydrogen storage alloy electrode and nickel metal hydride battery using the alloys

Abstract

A nickel metal hydride battery includes particles of hydrogen storage alloys in the negative electrode. Such hydrogen storage alloys have a composition expressed by a general formula: (LaaSmbAc)1-wMgwNixAlyTz. In the formula, A and T denote at least one element selected from the groups consisting of: Pr, Nd, and the like; and V, Nb, and the like, respectively, the subscripts a, b, and c satisfy the relationship given by: a>0; b>0; 0.1>c>=0; and a+b+c=1, and the subscripts w, x, y, and z fall within the range given by: 0.1<w<=1; 0.05<=y<=0.35; 0<=z<=0.5; and 3.2<=x+y+z<=3.8.

Description

technical field [0001] The invention relates to a hydrogen storage alloy, a hydrogen storage alloy electrode using the alloy, and a nickel-hydrogen secondary battery. Background technique [0002] In order to achieve higher performance of nickel-hydrogen secondary batteries, it has been proposed to use rare earth-Mg-Ni-based hydrogen storage alloys as negative electrode active materials. Rare-earth-Mg-Ni-based hydrogen storage alloys have a larger hydrogen storage capacity than conventionally used rare-earth-Ni-based hydrogen storage alloys, and are suitable for increasing the capacity of nickel-hydrogen secondary batteries. [0003] On the other hand, rare-earth-Mg-Ni-based hydrogen storage alloys have low alkali resistance, and a nickel-hydrogen secondary battery using this alloy suffers from a problem of reduced cycle life. In response to this problem, various studies have been made on the components of rare earths and proposals have been made. Among them are proposals t...

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Problems solved by technology

[0007] However, in the rare earth-Mg-Ni hydrogen storage alloys disclosed in Patent Documents 1 and 2, the hydrogen storage capacity decreases and the hydrogen equilibrium pressure increases, so the internal pressure of the battery tends to increase.

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