Patent ID: 8192862

Claim:
A battery pack comprising: a battery cell having a first opened end and a second opened end formed thereto; a circuit board electrically connected to the battery cell; a first cover housing the circuit board, and engaged with the first opened end; and a second cover engaged with the second opened end, wherein; the battery cell includes; a battery element; a rectangular first packaging component provided with at least a first metal layer, a first outer resin layer formed on one surface of the first metal layer, and a first inner resin layer formed on the other surface of the first metal layer, a recess being formed from the first inner resin layer side to the first outer resin layer side, and distance between the side periphery and the opposing side edge of the recess being not larger than the depth of the recess; and a rectangular second packaging component provided with at least a second metal layer, a second outer resin layer formed on one surface of the second metal layer, and a second inner resin layer formed on the other surface of the second metal layer, wherein; the battery element is housed in the recess, the first packaging component and the second packaging component are stacked so that the second packaging component covers the opening of the recess and the first packaging component does not cover the opening of the recess, the periphery of the opening is sealed, both ends of the second packaging component are abutted at the outer bottom surface of the recess of the first packaging component, and the first outer resin layer and the second inner resin layer are bonded by a heat seal adhesive layer having a thickness of 1 μm or larger and 20 μm or smaller interposed between the outer bottom surface of the recess of the first packaging component and both ends of the second packaging component, as being preliminarily provided to the second packaging component, and wherein the heat seal adhesive layer is formed in a region excluding (a) edges of the second packaging component and (b) where the second packaging component faces the battery element and the first packaging component.