Hydrogen storage alloy, hydrogen storage alloy electrode, secondary battery, and method for producing hydrogen storage alloy

Patent metadata

Field	Value
Publication number	US-2016333443-A1
Application number	US-201615219753-A
Country	US
Kind code	A1
Filing date	Jul 26, 2016
Priority date	Aug 9, 2006
Publication date	Nov 17, 2016
Grant date	—

Abstract

Provided is a hydrogen storage alloy which is characterized in that two or more crystal phases having different crystal structures are layered in a c-axis direction of the crystal structures. The hydrogen storage alloy is further characterized in that a difference between a maximum value and a minimum value of a lattice constant a in the crystal structures of the laminated two or more crystal phases is 0.03 Å or less.

First claim

1 . A hydrogen storage alloy containing two or more crystal phases having different crystal structures, wherein the two or more crystal phases are layered in the c-axis direction of the crystal structures.

2 . The hydrogen storage alloy according to claim 1 , wherein a difference between a maximum value and a minimum value of the lattice constant a in the crystal structures of said two or more crystal phases is 0.03 Å or less.

3 . The hydrogen storage alloy according claim 1 or 2 , wherein said crystal phases include two or more types selected from a group consisting of a crystal phase having La 5 MgNi 24 type crystal structure, a crystal phase having Pr 5 Co 19 type crystal structure, a crystal phase having Ce 5 Co 19 type crystal structure, and a crystal phase having Ce 2 Ni 7 type crystal structure.

4 . The hydrogen storage alloy according to any of claims 1 to 3 having a composition defined by a general formula R1 a R2 b R3 c (wherein R1 is one or more kind elements selected from a group consisting of rare earth metals including Y; R2 is one or more kind elements selected from a group consisting of Mg, Ca, Sr, and Ba; R3 is one or more kind elements selected from a group consisting of Ni, Co, Mn, Al, Cr, Fe, Cu, Zn, Si, Sn, V, Nb, Ta, Ti, Zr, and Hf; and a, b, and c satisfy 10≦a≦30; 1≦b≦10; 65≦c≦90; and a+b+c=100).

5 . The hydrogen storage alloy according to claim 1 having a composition defined by a general formula R1 d R2 e R4 f R5 g (wherein R1 is one or more kind elements selected from a group consisting of rare earth metals including Y; R2 is one or more kind elements selected from a group consisting of Mg, Ca, Sr, and Ba; R4 is one or more kind elements selected from a group consisting of Ni, Co, Cr, Fe, Cu, Zn, Si, Sn, V, Th, Ti, Zr, and Hf; R5 is one or two elements selected from Mn and Al; and d, e, f and g satisfy 8≦d≦19; 2≦e≦9; 73≦f≦79; 1≦g≦4; and d+e+f+g=100) and satisfying 3.53≦(B/A)≦3.80 and 0.0593(B/A)+1.69≦rA≦0.0063(B/A)+1.81 in the case (B/A) is defined as (f+g)/(d+e) and rA (Å) is defined as the average atomic radius of R1 and R2.

6 . The hydrogen storage alloy according to claim 5 , wherein the R1 is one or more kind elements R1′ selected from a group consisting of Ce, Pr, Nd, Sm, and Y and La at La/R1′ ratio of 5 or less; R2 is Mg; the R4 is one or two elements selected from Ni and Co; the R5 is Al; and the d, e, f, and g satisfy 16≦d≦19; 2: ≦e≦5; 73≦f≦78; and 2≦g≦4.

7 . The hydrogen storage alloy according to claim 5 or 6 having, as a main produced phase, a crystal phase having Pr 5 Co 19 type crystal structure or a crystal phase having Ce 5 Co 19 type crystal structure.

8 . The hydrogen storage alloy according claim 1 having, as a main produced phase, a crystal phase having Ce 5 Co 19 type crystal structure and a composition defined by a general formula La h R6 i R7 j Mg k R8 m (wherein R6 is one or more kind elements selected from a group consisting of rare earth metals including Y and excluding La; R7 is one or more kind elements selected from a group consisting of Zr, Ti, Zn, Sn and V; R8 is one or more kind elements selected from a group consisting of Ni, Co, Mn, Al, Cu, Fe, Cr, and Si; and h, i j, k and m satisfy 0≦j≦0.65; 2≦k≦5.5; 0.70≦h/(h+)≦0.85; and h+i*j+k+m=100).

9 . The hydrogen storage alloy according to claim 1 , wherein the ratio of the crystal phase having CaCu 5 type crystal structure is 22% by weight or less.

10 . The hydrogen storage alloy according to claim 9 , wherein the hydrogen equilibrium pressure is 0.07 MPa or less.

11 . The hydrogen storage alloy according to claim 9 or 10 having a composition defined by a general formula R1 n R2 p R4 q R5 r (wherein R1 is one or more kind elements selected from a group consisting of rare earth metals including Y; R2 is one or more kind elements selected from a group consisting of Mg, Ca, Sr, and Ba; R4 is one or more kind elements selected from a group consisting of Ni, Co, Cr, Fe, Cu, Zn, Si, Sn, Nb, Ta, Ti, Zr, and Hf; R5 is one or two kind elements selected from Mn and Al; and n, p, q, and r satisfy 16≦n≦23; 2≦p≦8; 68.5≦q≦76; 1≦r≦6.5; and n+p+q+r=100).

12 . The hydrogen storage alloy according to any of claims 9 to 11 , wherein the content of Mn is 5% by weight or less.

13 . A hydrogen storage alloy electrode using the hydrogen storage alloy according to any one of claims 1 to 12 as a hydrogen storage medium.

14 . A secondary battery using the hydrogen storage alloy electrode according to claim 13 as a negative electrode.

15 . A method for producing the hydrogen storage alloy according to any of claims 1 to 12 , comprising a melting step of heat melting alloy raw materials at prescribed mixing ratio in inert gas atmosphere; a cooling step of rapid solidification the melted alloy at a cooling speed of 1000° C./s or higher; and an annealing step of further annealing the alloy subjected to the cooling step at 860° C. or higher and 1000° C. or lower in inert gas atmosphere in pressurized state.

Assignees

• Gs Yuasa Int Ltd
• Nat Inst Advanced Ind Science & Tech

Inventors

• Kakeya Tadashi
• Kanemoto Manabu
• Kuzuhara Minoru
• Ozaki Tetsuya
• Watada Masaharu
• Sakai Tetsuo

Classifications

• C22C1/0441

  Alloys based on intermetallic compounds of the type rare earth - Co, Ni · CPC title

• C22C19/03 Primary

  based on nickel · CPC title

• H01M4/134

  Electrodes based on metals, Si or alloys · CPC title

• H01M2004/027

  Negative electrodes · CPC title

• C22F1/002

  by rapid cooling or quenching; cooling agents used therefor · CPC title