Battery pack

1. A battery pack comprising:

a plurality of battery stacks integrated by stacking a plurality of unit batteries;

a fluid passage only disposed between separate and adjacent battery stacks, the fluid passage extending in a stacking direction of the plurality of batteries, where fluid flows for cooling the plurality of unit batteries, the battery stacks disposed adjacent to each other in an aligning direction perpendicular to the stacking direction;

a fluid driver for circulating the fluid in the fluid passage;

a heat conducting member group including a plurality of heat conducting members each thermally connected to at least one of an outer casing or an electrode terminal of one of the plurality of unit batteries, the plurality of heat conducting members being aligned in the stacking direction;

a passage forming member that demarcates the fluid passage as an independent passage from an area near the outer casing of the unit batteries, and includes a partition wall for supporting the heat conducting members;

a plurality of cooled parts of the plurality of heat conducting members that project into the fluid passage, surface areas of individual cooled parts in a central part of the heat conducting member group in the stacking direction being larger than surface areas of individual cooled parts in ends of the heat conducting member group in the stacking direction, and each cooled part having a greater surface area at a downstream end thereof than an upstream end thereof relative to the fluid flow, all of the cooled parts protruding from a same battery stack overlapping in the fluid passage in the stacking direction; and

fins protruding from the cooled parts that overlap in the aligning direction.

2. The battery pack according to claim 1 , wherein,

each of the plurality of heat conducting members is integrally molded with the passage forming member so as to penetrate the partition wall.

3. The battery pack according to claim 1 , wherein,

each unit battery is a pouch cell with its outer casing formed of laminate films;

heat conducting members are stacked between the pouch cells and are heat conducting plates that constitute the battery stack together with the pouch cells; and

the heat conducting plates each include a terminal heat absorber that absorbs heat generated by the electrode terminal by contacting the electrode terminal in an area covered with the laminate films via the laminate films in the pouch cells adjoining in the stacking direction.

4. The battery pack according to claim 1 , wherein,

each unit battery is a pouch cell with its outer casing formed of laminate films;

heat conducting members are stacked between the pouch cells and are heat conducting plates that constitute the battery stack together with the pouch cells; and

each heat conducting plate includes a heat absorbing piece that extends therefrom, and the heat absorbing piece contacts the pouch cell in an area positioned away from the cooled part and in a downstream half of the pouch cell relative to the fluid flow, the heat absorbing piece contacting the pouch cell via the laminate films to absorb heat generated in the pouch cell.

5. The battery pack according to claim 1 , wherein,

the passage forming member is formed by combining a plurality of members in the stacking direction; and

sealers for preventing the fluid flowing through the fluid passage from leaking to outside are disposed to fitters between the plurality of members to be combined.