Abstract: There is provided a hydrogen-absorbing alloy comprising, as a principal phase, at least one kind of phase selected from the group consisting of a first phase having a hexagonal crystal system (excluding a phase having a CaCu5 type crystal structure) and a second phase having a rhombohedral crystal system, the hydrogen-absorbing alloy having a composition represented by the following general formula (1): R1-a-bMgaTbNiZ-X-Y-&agr;M1XM2YMn&agr;  (1) wherein R is at least one kind of element selected from rare earth elements (which include Y), T is at least one element selected from the group consisting of Ca, Ti, Zr and Hf, M1 is at least one element selected from the group consisting of Co and Fe, M2 is at least one element selected from the group consisting of Al, Ga, Zn, Sn, Cu, Si, B, Nb, W, Mo, V, Cr, Ta, Li, P and S, and the atomic ratios of a, b, X, Y, &agr; and Z are respectively a number satisfying the conditions of: 0.15≦a≦0.37, 0≦b≦0.3, 0≦X≦1.3, 0≦Y≦0.

Abstract: According to the present invention, a negative electrode material is provided. The negative electrode material is capable of storing and releasing lithium, and exhibits at least one peak of heat generation in the range of 200° C. to 450° C. in the differential scanning calorimetry (DSC) at a temperature rise speed of 10° C./min. and a peak derived from a crystalline phase in the X-ray diffraction.

Abstract: There is provided a hydrogen-absorbing alloy comprising, as a principal phase, at least one kind of phase selected from the group consisting of a first phase having a hexagonal crystal system (excluding a phase having a CaCu5 type crystal structure) and a second phase having a rhombohedral crystal system, the hydrogen-absorbing alloy having a composition represented by the following general formula (1):

Abstract: There is provided a hydrogen-absorbing alloy comprising, as a principal phase, at least one kind of phase selected from the group consisting of a first phase having a hexagonal crystal system (excluding a phase having a CaCu5 type crystal structure) and a second phase having a rhombohedral crystal system, the hydrogen-absorbing alloy having a composition represented by the following general formula (1): R1−a−bMgaTbNiZ−X−Y−&agr;M1XM2YMn60   (1) wherein R is at least one kind of element selected from rare earth elements (which include Y), T is at least one element selected from the group consisting of Ca, Ti, Zr and Hf, M1 is at least one element selected from the group consisting of Co and Fe, M2 is at least one element selected from the group consisting of Al, Ga, Zn, Sn, Cu, Si, B, Nb, W, Mo, V, Cr, Ta, Li, P and S, and the atomic ratios of a, b, X, Y, &agr; and Z are respectively a number satisfying the conditions of: 0.15≦a≦0.37, 0≦b≦0.3, 0≦X≦1.

Abstract: There is provided a nickel-hydrogen secondary battery which comprises a negative electrode comprising a hydrogen-absorbing alloy represented by the following general formula (A), a positive electrode, and an alkaline electrolyte, and which meets the conditions represented by the formulas (1) and (2), (R1-xMgx)NiyAz   (A) wherein R is at least one element selected from rare earth elements (including yttrium), Ca, Zr and Ti, A is at least one element selected from Co, Mn, Fe, V, Cr, Nb, Al, Ga, Zn, Sn, Cu, Si, P and B, and x, y and z are atomic ratio individually defined as 0<x<1, 0≦z≦1.5, 2.5≦y+z<4.5, 3.2≦P≦5.0   (1) 0.9≦Q≦0.2P+0.7   (2) wherein P is a quantity (g) of the hydrogen-absorbing alloy per theoretical capacity 1 Ah of the positive electrode, and Q is a quantity (mL) of the alkaline electrolyte per theoretical capacity 1 Ah of the positive electrode.

Abstract: There is provided a hydrogen-absorbing alloy comprising at least one crystal phase consisting essentially of at least one unit cell which has a laminate structure comprising at least one A2B4 subcell and at least one AB5 subcell, and the aforementioned at least one unit cell satisfying the following formula (1), 0.5<X<1  (1) wherein A is at least one kind of element which is capable of generating heat of formation &Dgr;H (kJ/mol) of less than 20 kJ/mol at the occasion of generating a hydride from one mole of hydrogen at a temperature of 25° C., B is at least one kind of element which is capable of generating heat of formation &Dgr;H (kJ/mol) of not less than 20 kJ/mol at the occasion of generating a hydride from one mole of hydrogen at a temperature of 25° C., and X is a ratio in number of the aforementioned at least one A2B4 subcell to the aforementioned at least one AB5 subcell.

Abstract: A nickel-hydrogen secondary battery having a negative electrode comprising a hydrogen-absorbing alloy containing magnesium, a rare earth element and nickel as essential elements, which is capable of suppressing the self-discharge being occurred under the condition of high temperature storage, or the like. This secondary battery comprises a negative electrode containing a hydrogen-absorbing alloy, a positive electrode containing nickel hydroxide, a separator comprising a non-woven fabric, and an alkaline electrolyte. The hydrogen-absorbing alloy is represented by (R1−xMgx)NiyAz (wherein R is at least one element selected from rare earth elements (including yttrium), Ca, Zr and Ti, A is at least one element selected from Co, Mn, Fe, V, Cr, Nb, Al, Ga, Zn, Sn, Cu, Si, P and B), and x, y and z are atomic ratio individually defined as 0<x<1, 0≦z≦1.5, 2.5≦y+z<4.5).