Steel foil for power storage device container, power storage device container, power storage device, and manufacturing method of steel foil for power storage device container
View Patent ↗A steel foil for a power storage device container includes a rolled steel foil, a nickel layer formed on a surface of the rolled steel foil, and a chromium-based surface treatment layer formed on a surface of the nickel layer. The nickel layer includes an upper layer portion which is in contact with the chromium-based surface treatment layer and contains Ni of 90 mass % or more among metal elements, and a lower layer portion which is in contact with the rolled steel foil and contains Ni of less than 90 mass % among the metal elements and Fe. <111> polar density in a reverse pole figure of the nickel layer in a rolling direction is 3.0 to 6.0. The nickel layer has a sub-boundary which is a boundary between two crystals having a relative orientation difference of 2° to 5°, and a large angle boundary which is a boundary between two crystals having the relative orientation difference of equal to or more than 15°. The average value of a ratio L 5 /L 15 between a boundary length L 5 which is the length of the sub-boundary, and a boundary length L 15 which is the length of the large angle boundary, is equal to or more than 1.0.
1. A steel foil for a power storage device container comprising:
a rolled steel foil;
a nickel layer which is formed on a surface of the rolled steel foil; and
a chromium-based surface treatment layer which is formed on a surface of the nickel layer,
wherein the nickel layer includes an upper layer portion which is in contact with the chromium-based surface treatment layer and contains Ni of 90 mass % or more among metal elements, and a lower layer portion which is in contact with the rolled steel foil and contains Ni of less than 90 mass % among the metal elements and Fe,
a <111> polar density in a reverse pole figure of the nickel layer in a rolling direction is 3.0 to 6.0,
the nickel layer has a sub-boundary which is a grain boundary between two crystals having a relative orientation difference of 2° to 5°, and a large angle boundary which is a grain boundary between two crystals having the relative orientation difference of equal to or more than 15°, and
an average value of a ratio L 5 /L 15 between a boundary length L 5 which is a length of the sub-boundary, and a boundary length L 15 which is a length of the large angle boundary, is equal to or more than 1.0.
2. The steel foil for a power storage device container according to claim 1 , wherein
an adhered amount of the nickel layer is equal to or more than 0.3 g/m 2 .
3. The steel foil for a power storage device container according to claim 2 , further comprising:
a polyolefin-based resin layer which is formed on a surface of the chromium-based surface treatment layer.
4. The steel foil for a power storage device container according to claim 1 , further comprising:
a polyolefin-based resin layer which is formed on a surface of the chromium-based surface treatment layer.
5. A power storage device container which includes the steel foil for a power storage device container according to claim 4 .
6. A power storage device comprising:
the power storage device container according to claim 5 .
7. A manufacturing method of a steel foil for a power storage device container, the method comprising:
a nickel-plating process of performing a nickel plating on a steel sheet so as to form a nickel-plated layer on the steel sheet, and obtaining a nickel-plated steel sheet;
a recrystallization annealing process of performing an annealing on the nickel-plated steel sheet so that the nickel-plated layer recrystallizes;
a cold-rolling process of performing a cold rolling on the nickel-plated steel sheet so as to obtain a steel foil; and
a chromium-based surface treatment process of performing a chromium-based surface treatment on the steel foil,
wherein in the cold-rolling process, the number of rolling passes is set to be equal to or more than seven passes, a reduction on a first rolling pass is set to be equal to or less than 30%, a cumulative rolling reduction until a fourth rolling pass is set to be equal to or less than 70%, a difference between a cumulative rolling reduction until a rolling pass before two passes from a final pass, and a cumulative rolling reduction until the final pass is set to be equal to or less than 5%, and the cumulative rolling reduction until the final pass is set to be equal to or more than 70%.
8. The manufacturing method of a steel foil for a power storage device container, according to claim 7 , wherein
in the nickel-plating process, an adhered amount of the nickel-plated layer is set to be equal to or more than 1 g/m 2 .
9. The manufacturing method of a steel foil for a power storage device container, according to claim 8 , further comprising:
a polyolefin resin layer forming process of forming a polyolefin resin layer on the surface of the steel foil after the chromium-based surface treatment process.
10. The manufacturing method of a steel foil for a power storage device container, according to claim 7 , further comprising:
a polyolefin resin layer forming process of forming a polyolefin resin layer on the surface of the steel foil after the chromium-based surface treatment process.