Secondary battery pouch
Embodiments provide a secondary battery pouch including a sealing portion formed at an outside of the secondary battery pouch constituting a battery cell and configured to seal an inner space of the secondary battery pouch. The sealing portion includes: a first fusion portion having a smallest thickness in the sealing portion; and a second fusion portion having a largest thickness in the sealing portion. The first fusion portion and the second fusion portion are continuously formed at least one time alternately in a direction from an innermost side of the sealing portion in contact with the inner space of the secondary battery pouch to an outer side of the sealing portion.
1 . A secondary battery pouch comprising:
a sealing portion formed at an outside of the secondary battery pouch constituting a battery cell and configured to seal an inner space of the secondary battery pouch, the sealing portion is formed by fusion of an upper sheet and a lower sheet,
wherein the sealing portion comprises:
a plurality of first fusion portions having a first seal strength and extending continuously along a longitudinal direction of the sealing portion disposed with electrode terminals of the battery cell; and
a plurality of second fusion portions having a second seal strength that is weaker than the first seal strength and extending continuously along the longitudinal direction of the sealing portion disposed with the electrode terminals of the battery cell,
wherein the first fusion portions and the second fusion portions are configured to provide stepwise sealing release in response to internal gas pressure increase,
wherein at least one of the second fusion portions is positioned at an innermost side of the sealing portion in contact with the inner space, and
wherein the first fusion portions and the remaining second fusion portions are arranged alternately toward the outer side of the sealing portion.
2 . The secondary battery pouch of claim 1 , wherein the first fusion portion has a strongest seal strength in the sealing portion, and
the second fusion portion has a weakest seal strength in the sealing portion.
3 . The secondary battery pouch of claim 1 , wherein each of the upper sheet and the lower sheet comprises a heat fusion layer, a metal layer, and an outer skin layer, and
each of the upper sheet and the lower sheet is configured such that a thickness of the heat fusion layer is 40 μm, and a total thickness of the metal layer and the outer skin layer is 95 μm.
4 . The secondary battery pouch of claim 3 , wherein the first fusion portion is formed to a thickness of 200 μm to 225 μm as the heat fusion layer of the first fusion portion is fused.
5 . The secondary battery pouch of claim 3 , wherein the second fusion portion is formed to a thickness of 225 μm to 250 μm as the heat fusion layer of the second fusion portion is fused.