Power supply device

A power supply device comprising:

• a plurality of secondary battery cells, each of the plurality of secondary battery cells including a relief valve configured to open when an internal pressure of the each of the plurality of secondary battery cells exceeds a predetermined pressure;
• an inner case accommodating the plurality of secondary battery cells therein;
• and
• an outer case covering the inner case, wherein
• the inner case includes an inner-side plate and an outer-side plate which constitute an outer circumferential wall of the inner case, and a portion of the inner-side plate and a portion of the outer-side plate overlap each other at a laminated portion constituting a laminated structure of the inner case,
• the laminated portion has a recess partially provided in one or both of a surface of the inner-side plate and a surface of the outer-side plate which face each other, the recess having a predetermined depth and extending in planar directions, the recess constituting a gas-exhaust duct closed between the inner-side plate and the outer-side plate,
• the gas-exhaust duct communicates with an inside of the inner case through an inner-side opening formed in the inner-side plate and communicates with an outside of the inner case through an outer-side opening formed in the outer-side plate, and
• the inner-side opening and the outer-side opening are disposed at opposite ends of the gas-exhaust duct.