Hydrogen-absorbing alloy electrode and method for evaluating hydrogen-absorbing alloys for electrode

A method for evaluating a hydrogen-absorbing alloy E as an electrode material, comprising the steps of:

• (1) measuring integrated intensities of X-ray diffraction peaks I.sub.M1 (h.sub.1 k.sub.1 l.sub.1), I.sub.M2 (h.sub.2 k.sub.2 l.sub.2) . . . , I.sub.Mx (h.sub.x k.sub.x l.sub.x) in lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . (h.sub.x k.sub.x l.sub.x), respectively, for a plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.x, each having a preferred orientation in lattice plane (h.sub.0 K.sub.0 l.sub.0) and having the same alloy composition as the hydrogen-absorbing alloy E, and measuring integrated intensities of X-ray diffraction peaks I.sub.s (h.sub.1 k.sub.1 l.sub.1), I.sub.s (h.sub.2 k.sub.2 l.sub.2) . . . , I.sub.s (h.sub.x k.sub.x l.sub.x) in lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . (h.sub.x k.sub.x l.sub.x), respectively, for a hydrogen-absorbing alloy S having the same alloy composition as the hydrogen-absorbing alloy E,
• determining integrated intensity ratios I.sub.M1 (h.sub.1 k.sub.1 l.sub.1)/I.sub.s (h.sub.1 k.sub.1 l.sub.1), I.sub.M2 (h.sub.2 k.sub.2 l.sub.2)/I.sub.s (h.sub.2 k.sub.2 l.sub.2), . . . , I.sub.Mx (h.sub.x k.sub.x l.sub.x)/I.sub.s (h.sub.x k.sub.x l.sub.x) and angles .phi..sub.1, .phi..sub.2, . . . , .phi..sub.x formed by the lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . , (h.sub.x k.sub.x l.sub.x) and the lattice plane (h.sub.0 k.sub.0 l.sub.0), respectively, and
• determining a parameter P, which varies according to a structure of the plurality of hydrogen absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.x and is a parameter of a function F(.phi.), where:
• F(.phi.)=I(hkl)/I.sub.s (hkl) (A)
• wherein I(hkl) is an integrated intensity of the X-ray diffraction peak in lattice plane (hkl) of the plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.x ;
• I.sub.s (hkl) is an integrated intensity of the X-ray diffraction peak in lattice plane (hkl) of the hydrogen-absorbing alloy S;
• and .phi. is an angle formed by the lattice plane (h.sub.0 k.sub.0 l.sub.0) and the lattice plane (hkl);
• (2) determining a relationship between the parameter P and observed values, T.sub.1, T.sub.2, . . . , T.sub.x representing at least one property of the plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.x as an electrode material;
• (3) measuring integrated intensities of X-ray diffraction peaks I.sub.E1 (h.sub.E1 K.sub.E1 l.sub.E1), I.sub.E2 (h.sub.E2 K.sub.E2 l.sub.E2), . . . , I.sub.EY (h.sub.EY k.sub.EY l.sub.EY) in lattice planes, (h.sub.E1 k.sub.E1 l.sub.E1), (h.sub.E2 k.sub.E2 l.sub.E2), . . . , (h.sub.EY k.sub.EY l.sub.EY), respectively, for the hydrogen-absorbing alloy E,
• determining integrated intensity ratios I.sub.E1 (h.sub.E1 k.sub.E1 l.sub.E1)/I.sub.s (h.sub.E1 k.sub.E1 l.sub.E1), I.sub.E2 (h.sub.E2 k.sub.E2 l.sub.E2)/I.sub.s (h.sub.E2 k.sub.E2 l.sub.E2), . . . , I.sub.EY (h.sub.EY k.sub.EY l.sub.EY)/I.sub.s (h.sub.EY k.sub.EY l.sub.EY), and angles .phi..sub.E1, .phi..sub.E2, . . . .phi..sub.EY formed by the lattice planes (h.sub.E1 k.sub.E1 l.sub.E1), (h.sub.E2 k.sub.E2 l.sub.E2), . . . , (h.sub.EY k.sub.EY l.sub.EY) and the lattice plane (h.sub.0 k.sub.0 l.sub.0), respectively, and
• determining a parameter P.sub.E for the hydrogen-absorbing alloy E by substituting the determined integrated intensity ratios and angles for I(hkl)/I.sub.s (hkl) and .phi. in formula (A);
• and
• (4) comparing the parameter P.sub.E with the relationship between the parameter P and the observed values T.sub.1, T.sub.2, . . . T.sub.x in step (2) to estimate at least one property of the hydrogen-absorbing alloy E, as an electrode material;
• wherein the hydrogen-absorbing alloy E is an AB.sub.5 alloy, where A is at least one element selected from the group consisting of rare earth metals and B is at least one transition element selected from the group consisting of Cr, Mn, Fe, Co, Mi, Cu, Sn, and Al, or an AB.sub.2 alloy, where A is at least one element selected from the group consisting of Ti, Zr, Cr, V and alkali earth metals and B is at least one transition element selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Sn, and Al.

A method for evaluating a hydrogen-absorbing alloy E as an electrode material, comprising the steps of:

• (1) measuring integrated intensities of X-ray diffraction peaks I.sub.M1 (h.sub.1 k.sub.1 l.sub.1), I.sub.M2 (h.sub.2 k.sub.2 l.sub.2) . . . , I.sub.Mx (h.sub.x k.sub.x l.sub.x) in lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . , (h.sub.x k.sub.x l.sub.x), respectively, for a plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.x, each having a preferred orientation in lattice plane (h.sub.0 K.sub.0 l.sub.0) and having the same alloy composition as the hydrogen-absorbing alloy E, and measuring integrated intensities of X-ray diffraction peaks I.sub.s (h.sub.1 k.sub.1 l.sub.1), I.sub.s (h.sub.2 k.sub.2 l.sub.2) . . . , I.sub.s (h.sub.x k.sub.x l.sub.x) in lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . (h.sub.x k.sub.x l.sub.x), respectively, for a hydrogen-absorbing alloy S having the same alloy composition as the hydrogen-absorbing alloy E,
• determining integrated intensity ratios I.sub.M1 (h.sub.1 k.sub.1 l.sub.1)/I.sub.s (h.sub.1 k.sub.1 l.sub.1), I.sub.M2 (h.sub.2 k.sub.2 l.sub.2)/I.sub.s (h.sub.2 k.sub.2 l.sub.2), . . . , I.sub.Mx (h.sub.x k.sub.x l.sub.x)/I.sub.s (h.sub.x k.sub.x l.sub.x) and angles .phi..sub.1, .phi..sub.2, . . . , .phi..sub.x formed by the lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . , (h.sub.x k.sub.x l.sub.x) and the lattice plane (h.sub.0 k.sub.0 l.sub.0), respectively, and
• determining a parameter P, which varies according to a structure of the plurality of hydrogen absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.x and is a parameter of a function F(.phi.), where:
• F(.phi.)=I(hkl)/I.sub.s (hkl) (A)
• wherein I(hkl) is an integrated intensity of the X-ray diffraction peak in lattice plane (hkl) of the plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.x ;
• I.sub.s (hkl) is an integrated intensity of the X-ray diffraction peak in lattice plane (hkl) of the hydrogen-absorbing alloy S;
• and .phi. is an angle formed by the lattice plane (h.sub.0 k.sub.0 l.sub.0) and the lattice plane (hkl);
• (2) determining a relationship between the parameter P and observed values, T.sub.1, T.sub.2, . . . , T.sub.x representing at least one property of the plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.x as an electrode material;
• (3) measuring integrated intensities of X-ray diffraction peaks I.sub.E1 (h.sub.E1 K.sub.E1 l.sub.E1), I.sub.E2 (h.sub.E2 K.sub.E2 l.sub.E2), . . . , I.sub.EY (h.sub.EY k.sub.EY l.sub.EY) in lattice planes, (h.sub.E1 k.sub.E1 l.sub.E1), (h.sub.E2 k.sub.E2 l.sub.E2), . . . , (h.sub.EY k.sub.EY l.sub.EY), respectively, for the hydrogen-absorbing alloy E,
• determining integrated intensity ratios I.sub.E1 (h.sub.E1 k.sub.E1 l.sub.E1)/I.sub.s (h.sub.E1 k.sub.E1 l.sub.E1), I.sub.E2 (h.sub.E2 k.sub.E2 l.sub.E2)/I.sub.s (h.sub.E2 k.sub.E2 l.sub.E2), . . . , I.sub.EY (h.sub.EY k.sub.EY l.sub.EY)/I.sub.s (h.sub.EY k.sub.EY l.sub.EY), and angles .phi..sub.E1, .phi..sub.E2, . . . , .phi..sub.EY formed by the lattice planes (h.sub.E1 k.sub.E1 l.sub.E1), (h.sub.E2 k.sub.E2 l.sub.E2), . . . , (h.sub.EY k.sub.EY l.sub.EY) and the lattice plane (h.sub.0 k.sub.0 l.sub.0), respectively, and
• determining a parameter P.sub.E for the hydrogen-absorbing alloy E by substituting the determined integrated intensity ratios and angles for I(hkl)/I.sub.s (hkl) and .phi. in formula (A);
• and
• (4) comparing the parameter P.sub.E with the relationship between the parameter P and the observed values T.sub.1, T.sub.2, . . . T.sub.x in step (2) to estimate at least one property of the hydrogen-absorbing alloy E, as an electrode material;
• wherein said method evaluates a crystal lattice of the hydrogen-absorbing alloy E for swelling or shrinking stress.

A method for evaluating a hydrogen-absorbing alloy E as an electrode material, comprising the steps of:

• (1) measuring integrated intensities of X-ray diffraction peaks I.sub.M1 (h.sub.1 k.sub.1 l.sub.1), I.sub.M2 (h.sub.2 k.sub.2 l.sub.2) . . . , I.sub.Mx (h.sub.x k.sub.x l.sub.x) in lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . , (h.sub.x k.sub.x l.sub.x), respectively, for a plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.x, each having a preferred orientation in lattice plane (h.sub.0 K.sub.0 l.sub.0) and having the same alloy composition as the hydrogen-absorbing alloy E, and measuring integrated intensities of X-ray diffraction peaks I.sub.s (h.sub.1 k.sub.1 l.sub.1), I.sub.s (h.sub.2 k.sub.2 l.sub.2) . . . , I.sub.s (h.sub.x k.sub.x l.sub.x) in lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . (h.sub.x k.sub.x l.sub.x), respectively, for a hydrogen-absorbing alloy S having the same alloy composition as the hydrogen-absorbing alloy E,
• determining integrated intensity ratios I.sub.M1 (h.sub.1 k.sub.1 l.sub.1)/I.sub.s (h.sub.1 k.sub.1 l.sub.1), I.sub.M2 (h.sub.2 k.sub.2 l.sub.2)/I.sub.s (h.sub.2 k.sub.2 l.sub.2), . . . , I.sub.Mx (h.sub.x k.sub.x l.sub.x)/I.sub.s (h.sub.x k.sub.x l.sub.x) and angles .phi..sub.1, .phi..sub.2, . . . , .phi..sub.x formed by the lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . , (h.sub.x k.sub.x l.sub.x) and the lattice plane (h.sub.0 k.sub.0 l.sub.0), respectively, and
• determining a parameter P, which varies according to a structure of the plurality of hydrogen absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.x and is a parameter of a function F(.phi.), where:
• F(.phi.)=I(hkl)/I.sub.s (hkl) (A)
• wherein I(hkl) is an integrated intensity of the X-ray diffraction peak in lattice plane (hkl) of the plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.x ;
• I.sub.s (hkl) is an integrated intensity of the X-ray diffraction peak in lattice plane (hkl) of the hydrogen-absorbing alloy S;
• and .phi. is an angle formed by the lattice plane (h.sub.0 k.sub.0 l.sub.0) and the lattice plane (hkl);
• (2) determining a relationship between the parameter P and observed values, T.sub.1, T.sub.2, . . . , T.sub.x representing at least one property of the plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.x as an electrode material;
• (3) measuring integrated intensities of X-ray diffraction peaks I.sub.E1 (h.sub.E1 K.sub.E1 l.sub.E1), I.sub.E2 (h.sub.E2 K.sub.E2 l.sub.E2), . . . , I.sub.EY (h.sub.EY k.sub.EY l.sub.EY) in lattice planes, (h.sub.E1 k.sub.E1 l.sub.E1), (h.sub.E2 k.sub.E2 l.sub.E2), . . . , (h.sub.EY k.sub.EY l.sub.EY), respectively, for the hydrogen-absorbing alloy E,
• determining integrated intensity ratios I.sub.E1 (h.sub.E1 k.sub.E1 l.sub.E1)/I.sub.s (h.sub.E1 k.sub.E1 l.sub.E1), I.sub.E2 (h.sub.E2 k.sub.E2 l.sub.E2)/I.sub.s (h.sub.E2 k.sub.E2 l.sub.E2), . . . , I.sub.EY (h.sub.EY k.sub.EY l.sub.EY)/I.sub.s (h.sub.EY k.sub.EY l.sub.EY), and angles .phi..sub.E1, .phi..sub.E2, . . . , .phi..sub.EY formed by the lattice planes (h.sub.E1 k.sub.E1 l.sub.E1), (h.sub.E2 k.sub.E2 l.sub.E2), . . . , (h.sub.EY k.sub.EY l.sub.EY) and the lattice plane (h.sub.0 k.sub.0 l.sub.0), respectively, and
• determining a parameter P.sub.E for the hydrogen-absorbing alloy E by substituting the determined integrated intensity ratios and angles for I(hkl)/I.sub.s (hkl) and .phi. in formula (A);
• and
• (4) comparing the parameter P.sub.E with the relationship between the parameter P and the observed values T.sub.1, T.sub.2, . . . T.sub.x in step (2) to estimate at least one property of the hydrogen-absorbing alloy E, as an electrode material;
• wherein the at least one property of the hydrogen-absorbing alloy E estimated in said step (4) is one of corrosion resistance, initial electrode capacity, retention of capacity, and a degree of activation.

A method for evaluating a hydrogen-absorbing alloy E as an electrode material, comprising the steps of:

• (1) measuring integrated intensities of X-ray diffraction peaks I.sub.M1 (h.sub.1 k.sub.1 l.sub.1), I.sub.M2 (h.sub.2 k.sub.2 l.sub.2) . . . , I.sub.Mx (h.sub.x k.sub.x l.sub.x) in lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . (h.sub.x k.sub.x l.sub.x), respectively, for a plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.X, each having a preferred orientation in lattice plane (h.sub.0 k.sub.0 l.sub.0) and having the same alloy composition as the hydrogen-absorbing alloy E, and measuring integrated intensities of X-ray diffraction peaks I.sub.s (h.sub.1 k.sub.1 l.sub.1), I.sub.s (h.sub.2 k.sub.2 l.sub.2) . . . , I.sub.s (h.sub.x k.sub.x l.sub.x) in lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . (h.sub.x k.sub.x l.sub.x), respectively, for a hydrogen-absorbing alloy S having the same alloy composition as the hydrogen-absorbing alloy E,
• determining integrated intensity ratios I.sub.M1 (h.sub.1 k.sub.1 l.sub.1)/I.sub.S (h.sub.1 k.sub.1 l.sub.1), I.sub.M2 (h.sub.2 k.sub.2 l.sub.2)/I.sub.S (h.sub.2 k.sub.2 l.sub.2), . . . , I.sub.MX (h.sub.x k.sub.x l.sub.x)/I.sub.S (h.sub.X k.sub.X l.sub.X) and angles .phi..sub.1, .phi..sub.2, . . . , .phi..sub.X formed by the lattice plane (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . , (h.sub.X k.sub.X l.sub.X) and the lattice plane (h.sub.0 k.sub.0 l.sub.0), respectively, and
• determining parameters P.sub.A and P.sub.B, which vary according to a structure of the plurality of hydrogen absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.x and are parameters of a function F(.phi.), where:
• F(.phi.)=P.sub.A +(1-P.sub.A)exp(-P.sub.B .multidot..phi..sup.2)=I(hkl)/I.sub.S (hkl) (B)
• wherein I(hkl) is an integrated intensity of the X-ray diffraction peak in lattice plane (hkl) of the plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.X ;
• I.sub.S (hkl) is an integrated intensity of the X-ray diffraction peak in lattice plane (hkl) of the hydrogen-absorbing alloy S;
• and .phi. is an angle formed by the lattice plane (h.sub.0 k.sub.0 l.sub.0) and the lattice plane (hkl);
• (2) determining a relationship between the parameters P.sub.A and/or P.sub.B and observed values, T.sub.1, T.sub.2, . . . , T.sub.X representing at least one property of the plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.X as an electrode material;
• (3) measuring integrated intensities of X-ray diffraction peaks I.sub.E1 (h.sub.E1 k.sub.E1 l.sub.E1), I.sub.E2 (h.sub.E2 k.sub.E2 l.sub.E2), . . . , I.sub.EY (h.sub.EY k.sub.EY l.sub.EY) in selected lattice planes, (h.sub.E1 k.sub.E1 l.sub.E1), (h.sub.E2 k.sub.E2 l.sub.E2), . . . , (h.sub.EY k.sub.EY l.sub.EY), respectively, for the hydrogen-absorbing alloy E,
• determining integrated intensity ratios I.sub.E1 (h.sub.E1 k.sub.E1 l.sub.E1)/I.sub.S (h.sub.E1 k.sub.E1 l.sub.E1), I.sub.E2 (h.sub.E2 k.sub.E2 l.sub.E2)/I.sub.S (h.sub.E2 k.sub.E2 l.sub.E2), . . . , I.sub.EY (h.sub.EY k.sub.EY l.sub.EY)/I.sub.S (h.sub.EY k.sub.EY l.sub.EY) and angles .phi..sub.E1, .phi..sub.E2, . . . , .phi..sub.EY formed by the lattice planes (h.sub.E1 k.sub.E1 l.sub.E1), (h.sub.E2 k.sub.E2 l.sub.E3), . . . , (h.sub.EY k.sub.EY l.sub.EY) and the lattice plane (h.sub.0 k.sub.0 l.sub.0), respectively, and
• determining parameters P.sub.EA and/or P.sub.EB for the hydrogen-absorbing alloy E, by substituting the determined integrated intensity ratios and angle for I(hkl)/I.sub.S (hkl) and .phi. in formula (B);
• and
• (4) comparing the parameters P.sub.EA and/or P.sub.EB with the relationship between parameters P.sub.A and/or P.sub.B and the observed values T.sub.1, T.sub.2, . . . , T.sub.x in step (2) to estimate at least one property of the hydrogen-absorbing alloy E as an electrode material;
• wherein the hydrogen-absorbing alloy E is used as a negative electrode of a metal hydride alkaline secondary battery.

A method for evaluating a hydrogen-absorbing alloy E as an electrode material, comprising the steps of:

• (1) measuring integrated intensities of X-ray diffraction peaks I.sub.M1 (h.sub.1 k.sub.1 l.sub.1), I.sub.M2 (h.sub.2 k.sub.2 l.sub.2) . . . , I.sub.Mx (h.sub.x k.sub.x l.sub.x) in lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . (h.sub.x k.sub.x l.sub.x), respectively, for a plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.X, each having a preferred orientation in lattice plane (h.sub.0 k.sub.0 l.sub.0) and having the same alloy composition as the hydrogen-absorbing alloy E, and measuring integrated intensities of X-ray diffraction peaks I.sub.s (h.sub.1 k.sub.1 l.sub.1), I.sub.s (h.sub.2 k.sub.2 l.sub.2) . . . , I.sub.s (h.sub.x k.sub.x l.sub.x) in lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . (h.sub.x k.sub.x l.sub.x), respectively, for a hydrogen-absorbing alloy S having the same alloy composition as the hydrogen-absorbing alloy E,
• determining integrated intensity ratios I.sub.M1 (h.sub.1 k.sub.1 l.sub.1)/I.sub.S (h.sub.1 k.sub.1 l.sub.1), I.sub.M2 (h.sub.2 k.sub.2 l.sub.2)/I.sub.S (h.sub.2 k.sub.2 l.sub.2), . . . , I.sub.MX (h.sub.x k.sub.x l.sub.x)/I.sub.S (h.sub.X k.sub.X l.sub.X) and angles .phi..sub.1, .phi..sub.2, . . . , .phi..sub.X formed by the lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . , (h.sub.X k.sub.X l.sub.X) and the lattice plane (h.sub.0 k.sub.0 l.sub.0), respectively, and
• determining parameters P.sub.A and P.sub.B, which vary according to a structure of the plurality of hydrogen absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.x and are parameters of a function F(.phi.), where:
• F(.phi.)=P.sub.A +(1-P.sub.A)exp(-P.sub.B .multidot..phi..sup.2)=I(hkl)/I.sub.S (hkl) (B)
• wherein I(hkl) is an integrated intensity of the X-ray diffraction peak in lattice plane (hkl) of the plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.X ;
• I.sub.S (hkl) is an integrated intensity of the X-ray diffraction peak in lattice plane (hkl) of the hydrogen-absorbing alloy S;
• and .phi. is an angle formed by the lattice plane (h.sub.0 k.sub.0 l.sub.0) and the lattice plane (hkl);
• (2) determining a relationship between the parameters P.sub.A and/or P.sub.B and observed values, T.sub.1, T.sub.2, . . . , T.sub.X representing at least one property of the plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.X as an electrode material;
• (3) measuring integrated intensities of X-ray diffraction peaks I.sub.E1 (h.sub.E1 k.sub.E1 l.sub.E1), I.sub.E2 (h.sub.E2 k.sub.E2 l.sub.E2), . . . , I.sub.EY (h.sub.EY k.sub.EY l.sub.EY) in selected lattice planes (h.sub.E1 k.sub.E1 l.sub.E1), (h.sub.E2 k.sub.E2 l.sub.E2), . . . , (h.sub.EY k.sub.EY l.sub.EY), respectively, for the hydrogen-absorbing alloy E,
• determining integrated intensity ratios I.sub.E1 (h.sub.E1 k.sub.E1 l.sub.E1)/I.sub.S (h.sub.E1 k.sub.E1 l.sub.E1), I.sub.E2 (h.sub.E2 k.sub.E2 l.sub.E2)/I.sub.S (h.sub.E2 k.sub.E2 l.sub.E2), . . . , I.sub.EY (h.sub.EY k.sub.EY l.sub.EY)/I.sub.S (h.sub.EY k.sub.EY l.sub.EY) and angles .phi..sub.E1, .phi..sub.E2, . . . .phi..sub.EY formed by the lattice planes (h.sub.E1 k.sub.E1 l.sub.E1), (h.sub.E2 k.sub.E2 l.sub.E3), . . . , (h.sub.EY k.sub.EY l.sub.EY) and the lattice plane (h.sub.0 k.sub.0 l.sub.0), respectively, and
• determining parameters P.sub.EA and/or P.sub.EB for the hydrogen-absorbing alloy E, by substituting the determined integrated intensity ratios and angles for I(hkl)/I.sub.S (hkl) and .phi. in formula (B);
• and
• (4) comparing the parameters P.sub.EA and/or P.sub.EB with the relationship between the parameters P.sub.A and/or P.sub.B and the observed values T.sub.1, T.sub.2, . . . T.sub.x in step (2) to estimate at least one property of the hydrogen-absorbing alloy E as an electrode material;
• wherein the hydrogen-absorbing alloy E is an AB.sub.5 alloy, where A is at least one element selected from the group consisting of rare earth metals and B is at least one transition element selected from the group consisting of Cr, Mn, Fe, Co, Mi, Cu, Sn, and Al, or an AB.sub.2 alloy, where A is at least one element selected from the group consisting of Ti, Zr, Cr, V and alkali earth metals and B is at least one transition element selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Sn, and Al.

A method for evaluating a hydrogen-absorbing alloy E as an electrode material, comprising the steps of:

• (1) measuring integrated intensities of X-ray diffraction peaks I.sub.M1 (h.sub.1 k.sub.1 l.sub.1), I.sub.M2 (h.sub.2 k.sub.2 l.sub.2) . . . , I.sub.Mx (h.sub.x k.sub.x l.sub.x) in lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . , (h.sub.x k.sub.x l.sub.x), respectively, for a plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.X, each having a preferred orientation in lattice plane (h.sub.0 k.sub.0 l.sub.0) and having the same alloy composition as the hydrogen-absorbing alloy E, and measuring integrated intensities of X-ray diffraction peaks I.sub.s (h.sub.1 k.sub.1 l.sub.1), I.sub.s (h.sub.2 k.sub.2 l.sub.2) . . . , I.sub.s (h.sub.x k.sub.x l.sub.x) in lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . (h.sub.x k.sub.x l.sub.x), respectively, for a hydrogen-absorbing alloy S having the same alloy composition as the hydrogen-absorbing alloy E,
• determining integrated intensity ratios I.sub.M1 (h.sub.1 k.sub.1 l.sub.1)/I.sub.S (h.sub.1 k.sub.1 l.sub.1), I.sub.M2 (h.sub.2 k.sub.2 l.sub.2)/I.sub.S (h.sub.2 k.sub.2 l.sub.2), . . . , I.sub.MX (h.sub.x k.sub.x l.sub.x)/I.sub.S (h.sub.X k.sub.X l.sub.X) and angles .phi..sub.1, .phi..sub.2, . . . , .phi..sub.X formed by the lattice plane (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . , (h.sub.X k.sub.X l.sub.X) and the lattice plane (h.sub.0 k.sub.0 l.sub.0), respectively, and
• determining parameters P.sub.A and P.sub.B, which vary according to a structure of the plurality of hydrogen absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.x and are parameters of a function F(.phi.), where:
• F(.phi.)=P.sub.A +(1-P.sub.A)exp(-P.sub.B .multidot..phi..sup.2)=I(hkl)/I.sub.S (hkl) (B)
• wherein I(hkl) is an integrated intensity of the X-ray diffraction peak in lattice plane (hkl) of the plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.X ;
• I.sub.S (hkl) is an integrated intensity of the X-ray diffraction peak in lattice plane (hkl) of the hydrogen-absorbing alloy S;
• and .phi. is an angle formed by the lattice plane (h.sub.0 k.sub.0 l.sub.0) and the lattice plane (hkl);
• (2) determining a relationship between the parameters P.sub.A and/or P.sub.B and observed values, T.sub.1, T.sub.2, . . . , T.sub.X representing at least one property of the plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.X as an electrode material;
• (3) measuring integrated intensities of X-ray diffraction peaks I.sub.E1 (h.sub.E1 k.sub.E1 l.sub.E1), I.sub.E2 (h.sub.E2 k.sub.E2 l.sub.E2), . . . , I.sub.EY (h.sub.EY k.sub.EY l.sub.EY) in selected lattice planes (h.sub.E1 k.sub.E1 l.sub.E1), (h.sub.E2 k.sub.E2 l.sub.E2), . . . , (h.sub.EY k.sub.EY l.sub.EY), respectively, for the hydrogen-absorbing alloy E,
• determining integrated intensity ratios I.sub.E1 (h.sub.E1 k.sub.E1 l.sub.E1)/I.sub.S (h.sub.E1 k.sub.E1 l.sub.E1), I.sub.E2 (h.sub.E2 k.sub.E2 l.sub.E2)/I.sub.S (h.sub.E2 k.sub.E2 l.sub.E2), . . . , I.sub.EY (h.sub.EY k.sub.EY l.sub.EY)/I.sub.S (h.sub.EY k.sub.EY l.sub.EY), and angles .phi..sub.E1, .phi..sub.E2, . . . , .phi..sub.EY formed by the lattice planes (h.sub.E1 k.sub.E1 l.sub.E1), (h.sub.E2 k.sub.E2 l.sub.E3), . . . , (h.sub.EY k.sub.EY l.sub.EY) and the lattice plane (h.sub.0 k.sub.0 l.sub.0), respectively, and
• determining parameters P.sub.EA and/or P.sub.EB for the hydrogen-absorbing alloy E, by substituting the determined integrated intensity ratios and angles for I(hkl)/I.sub.S (hkl) and .phi. in formula (B);
• and
• (4) comparing the parameters P.sub.EA and/or P.sub.EB with the relationship between the parameters P.sub.A and/or P.sub.B and the observed values T.sub.1, T.sub.2, . . . , T.sub.x in step (2) to estimate at least one property of the hydrogen-absorbing alloy E, as an electrode material;
• wherein said method evaluates a crystal lattice of the hydrogen-absorbing alloy E for swelling or shrinking stress.

A method for evaluating a hydrogen-absorbing alloy E as an electrode material, comprising the steps of:

• (1) measuring integrated intensities of X-ray diffraction peaks I.sub.M1 (h.sub.1 k.sub.1 l.sub.1), I.sub.M2 (h.sub.2 k.sub.2 l.sub.2) . . . , I.sub.Mx (h.sub.x k.sub.x l.sub.x) in lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . (h.sub.x k.sub.x l.sub.x), respectively, for a plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.X, each having a preferred orientation in lattice plane (h.sub.0 k.sub.0 l.sub.0) and having the same alloy composition as the hydrogen-absorbing alloy E, and measuring integrated intensities of X-ray diffraction peaks I.sub.s (h.sub.1 k.sub.1 l.sub.1), I.sub.s (h.sub.2 k.sub.2 l.sub.2) . . . , I.sub.s (h.sub.x k.sub.x l.sub.x) in lattice planes (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . (h.sub.x k.sub.x l.sub.x), respectively, for a hydrogen-absorbing alloy S having the same alloy composition as the hydrogen-absorbing alloy E,
• determining integrated intensity ratios I.sub.M1 (h.sub.1 k.sub.1 l.sub.1)/I.sub.S (h.sub.1 k.sub.1 l.sub.1), I.sub.M2 (h.sub.2 k.sub.2 l.sub.2)/I.sub.S (h.sub.2 k.sub.2 l.sub.2), . . . , I.sub.MX (h.sub.x k.sub.x l.sub.x)/I.sub.S (h.sub.X k.sub.X l.sub.X) and angles .phi..sub.1, .phi..sub.2, . . . , .phi..sub.X formed by the lattice plane (h.sub.1 k.sub.1 l.sub.1), (h.sub.2 k.sub.2 l.sub.2), . . . , (h.sub.X k.sub.X l.sub.X) and the lattice plane (h.sub.0 k.sub.0 l.sub.0), respectively, and
• determining parameters P.sub.A and P.sub.B, which vary according to a structure of the plurality of hydrogen absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.x and are parameters of a function F(.phi.), where:
• F(.phi.)=P.sub.A +(1-P.sub.A)exp(-P.sub.B .multidot..phi..sup.2)=I(hkl)/I.sub.S (hkl) (B)
• wherein I(hkl) is an integrated intensity of the X-ray diffraction peak in lattice plane (hkl) of the plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.X ;
• I.sub.S (hkl) is an integrated intensity of the X-ray diffraction peak in lattice plane (hkl) of the hydrogen-absorbing alloy S;
• and .phi. is an angle formed by the lattice plane (h.sub.0 k.sub.0 l.sub.0) and the lattice plane (hkl);
• (2) determining a relationship between the parameters P.sub.A and/or P.sub.B and observed values, T.sub.1, T.sub.2, . . . , T.sub.X representing at least one property of the plurality of hydrogen-absorbing alloys M.sub.1, M.sub.2, . . . , M.sub.X as an electrode material;
• (3) measuring integrated intensities of X-ray diffraction peaks I.sub.E1 (h.sub.E1 k.sub.E1 l.sub.E1), I.sub.E2 (h.sub.E2 k.sub.E2 l.sub.E2), . . . , I.sub.EY (h.sub.EY k.sub.EY l.sub.EY) in selected lattice planes (h.sub.E1 k.sub.E1 l.sub.E1), (h.sub.E2 k.sub.E2 l.sub.E2), . . . , (h.sub.EY k.sub.EY l.sub.EY), respectively, for the hydrogen-absorbing alloy E,
• determining integrated intensity ratios I.sub.E1 (h.sub.E1 k.sub.E1 l.sub.E1), /I.sub.S (h.sub.E1 k.sub.E1 l.sub.E1), I.sub.E2 (h.sub.E2 k.sub.E2 l.sub.E2)/I.sub.S (h.sub.E2 k.sub.E2 l.sub.E2), . . . , I.sub.EY (h.sub.EY k.sub.EY l.sub.EY)/I.sub.S (h.sub.EY k.sub.EY l.sub.EY) and angles .phi..sub.E1, .phi..sub.E2, . . . , .phi..sub.EY formed by the lattice planes (h.sub.E1 k.sub.E1 l.sub.E1), (h.sub.E2 k.sub.E2 l.sub.E3), . . . , (h.sub.EY k.sub.EY l.sub.EY) and the lattice plane (h.sub.0 k.sub.0 l.sub.0), respectively, and
• determining parameters P.sub.EA and/or P.sub.EB for the hydrogen-absorbing alloy E, by substituting the determined integrated intensity ratios and angles for I(hkl)/I.sub.S (hkl) and .phi. in formula (B);
• and
• (4) comparing the parameters P.sub.EA and/or P.sub.EB with the relationship between the parameters P.sub.A and/or P.sub.B and the observed values T.sub.1, T.sub.2, . . . , T.sub.x in step (2) to estimate at least one property of the hydrogen-absorbing alloy E as an electrode material;
• wherein the at least one property of the hydrogen-absorbing alloy E estimated in said step (4) is one of corrosion resistance, initial electrode capacity, retention of capacity, and a degree of activation.