Power supply device and electric vehicle and power storage device using same, fastening member for power supply device, production method for power supply device, and production method for fastening member for power supply device

A fastening member for a power supply device for fastening a pair of end plates covering both end surfaces of a battery stack body in which a plurality of secondary battery cells each including a prismatic exterior can are stacked, the fastening member comprising:

• fastening portions including a first metal, the fastening portions being fixed to each of the end plates at each of both ends in a longer direction;
• and
• an intermediate portion including a second metal different from the first metal, the intermediate portion coupling the fastening portions with each other, wherein
• the first metal is higher in strength than the second metal, and
• the second metal is higher in stretchability than the first metal.

A production method for a fastening member for a power supply device for fastening a pair of end plates covering both end surfaces of a battery stack body in which a plurality of secondary battery cells each including a prismatic exterior can are stacked, the production method comprising the steps of:

• preparing a fastening portion and an intermediate portion,
• the fastening portions including a first metal, the fastening portions being fixed to each of the end plates at each of both ends in a longer direction, the intermediate portion including a second metal different from the first metal, the intermediate portion coupling the fastening portions with each other, the first metal being higher in strength than the second metal, the second metal being higher in stretchability than the first metal;
• and
• welding, by friction stir welding, the fastening portions and the intermediate portion.

A production method for a power supply device, the power supply device including

• a plurality of secondary battery cells each including a prismatic exterior can,
• a pair of end plates covering both end surfaces of a battery stack body in which the plurality of secondary battery cells are stacked, and
• a plurality of fastening members each containing metal and including a plate shape extending in a stack direction of the plurality of secondary battery cells, the plurality of fastening members being disposed on opposing side surfaces of the battery stack body to fasten the end plates to each other, the production method comprising:
• welding, by friction stir welding, a fastening portion and an intermediate portion, the fastening portions including a first metal, the fastening portions being fixed to each of the end plate at each of both ends in a longer direction, the intermediate portion including a second metal different from the first metal, the intermediate portion coupling the fastening portions with each other,
• the first metal being higher in strength than the second metal, the second metal being higher in stretchability than the first metal;
• and
• covering both end surfaces of the battery stack body with the pair of the end plates and fastening the end plates to each other with a fastening member for a power supply device.