Battery reinforcement method

1. A battery reinforcement method for reinforcing a rectangular battery cell in which a battery element is disposed in a rectangular external packaging, the method comprising:

enclosing the battery element between two rectangular external packaging sheets and sealing the rectangular external packaging sheets with a sealing part that extends around an entire circumference of the battery element so as to form the rectangular external packaging, the rectangular external packaging having at least four sides, each of the sides having an edge, the sealing part being separated from the edges of at least three of the sides such that the sealing part is disposed between the battery element and the edges of the at least three sides of the rectangular external packaging;

forming a reinforcing part on at least one of the at least three sides of the rectangular external packaging such that an elongated gap exists between the sealing part and the reinforcing part, the reinforcing part being located in a region between the sealing part and the edge of the at least one of the at least three sides of the rectangular external packaging from which the sealing part is separated, the gap extending parallel to the edge of the at least one of the at least three sides such that the reinforcing part is separated from the sealing part by the gap and does not overlap the sealing part;

forming each of the two rectangular external packaging sheets by coating a metal sheet with a resin; and

forming the sealing part and reinforcing part independently from each other by thermocompression-bonding the resin that coats the two external packaging sheets.

2. The battery reinforcement method according to claim 1 , wherein

the forming the reinforcing part includes forming the reinforcing part on at least a part of a first side among the sides of the rectangular external packaging, the first side being different from a second side among the sides of the rectangular external packaging that is used for discharging gas.

3. The battery reinforcement method according claim 1 , further comprising

correcting deformation of the region in which the reinforcing part is to be formed,

the forming the reinforcing part being performed such that the reinforcing part spans fully to the edge of the at least one of the at least three of the sides of the rectangular external packaging, and

the correcting deformation being performed prior to the forming the reinforcing part.

4. The battery reinforcement method according to claim 3 , further comprising

detecting deformation of the region in which the reinforcing part is to be formed, the detecting deformation being performed prior to the forming the reinforcing part.

5. The battery reinforcement method according to claim 1 , wherein

the forming of the reinforcing part being performed such that the reinforcing part spans fully to the edge of one of the at least three sides of the rectangular external packaging, the one side being a side that is in contact with a device when the battery cell is transferred to or received from the device.

6. The battery reinforcement method according to claim 1 , wherein

the forming the reinforcing part being performed such that the reinforcing part spans fully to the edge of the at least one of the at least three of the sides of the rectangular external packaging, and

the forming the reinforcing part including rounding corners of the at least one side on which the reinforcing part has been formed.

7. The battery reinforcement method according to claim 6 , further comprising

cutting a portion of the at least one side on which the reinforcing part has been formed.

8. The battery reinforcement method according claim 2 , further comprising

correcting deformation of a portion of at least the first side on which the reinforcing part is to be formed,

the forming the reinforcing part being performed such that the reinforcing spans fully to the edge of the first side of the rectangular external packaging, and the correcting deformation being performed prior to the forming the reinforcing part.

9. The battery reinforcement method according to claim 8 , further comprising

detecting deformation of the region in which the reinforcing part is to be formed, the detecting deformation being performed prior to the forming the reinforcing part.

10. The battery reinforcement method according to claim 8 , wherein

the forming of the reinforcing part being performed such that the reinforcing part spans fully to the edge of the first side of the rectangular external packaging,

the first side is a side that is in contact with a device when the battery cell is transferred to or received from the device.

11. The battery reinforcement method according to claim 8 , further comprising

rounding corners of at least the first side of the rectangular external packaging.

12. The battery reinforcement method according to claim 11 , further comprising

cutting a portion of at least the first side of the rectangular external packaging.

13. The battery reinforcement method according to claim 1 , wherein

the forming the reinforcing part is performed after the forming the sealing part.

14. The battery reinforcement method according to claim 1 , wherein

the sealing part is formed to have a shape that protrudes outward toward an edge of the rectangular external packaging that is different from the edge of the at least one side on which the reinforcing part is formed.

15. The battery reinforcement method according to claim 14 , wherein

the reinforcing part is formed on one of the four sides of the rectangular external packaging, and the protruding shape of the sealing part protrudes toward the edge of another side of the rectangular external packaging that is opposite the side on which the reinforcing part is formed.