1 . A battery cell, comprising:
a battery case having an accommodation portion in which an electrode assembly is mounted, and a sealing portion formed by sealing an outer periphery thereof; an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding out of the battery case via the sealing portion; and a lead film located at a portion corresponding to the sealing portion in at least one of an upper portion and a lower portion of the electrode lead, wherein the lead film includes a first stepped portion protruding in a direction opposite to the electrode lead, the sealing portion includes a second stepped portion surrounding an outer surface of the first stepped portion, and a gas discharge guiding unit is inserted in the first stepped portion.
2 . The battery cell according to claim 1 ,
wherein a first step of the first stepped portion and a second step of the second stepped portion have a size corresponding to a height of the gas discharge guiding unit, respectively.
3 . The battery cell according to claim 2 ,
wherein the first step and the second step have the same size.
4 . The battery cell according to claim 1 ,
wherein the gas discharge guiding unit is located on a center of the electrode lead based on a width direction of the lead film.
5 . The battery cell according to claim 1 ,
wherein the gas discharge guiding unit extends along a protruding direction of the electrode lead, and an end of the gas discharge guiding unit adjacent to an outer side of the battery case is surrounded with the lead film.
6 . The battery cell according to claim 5 ,
wherein an end of the gas discharge guiding unit adjacent to an inner side of the battery case is exposed inside the battery case.
7 . The battery cell according to claim 1 ,
wherein a gas discharge path is formed at an interface between the gas discharge guiding unit and the lead film.
8 . The battery cell according to claim 7 ,
wherein an adhesive force between the gas discharge guiding unit and the lead film is smaller than at least one of an adhesive force between the lead film and the electrode lead and or an adhesive force between the lead film and the sealing portion.
9 . The battery cell according to claim 8 ,
wherein the gas discharge guiding unit is a film layer made of polyimide or polyethylene terephthalate.
10 . The battery cell according to claim 8 ,
wherein the gas discharge guiding unit is a coating layer made of liquid resin.
11 . The battery cell according to claim 8 ,
wherein the gas discharge guiding unit further includes a getter material containing at least calcium oxide (CaO), lithium chloride (LiCl), silica (SiO 2 ), barium oxide (BaO), barium (Ba), and or calcium (Ca).
12 . The battery cell according to claim 1 ,
wherein the second stepped portion is formed to have a uniform thickness.
13 . The battery cell according to claim 1 ,
wherein the gas discharge guiding unit is located on the electrode lead, and an adhesive layer is formed between the gas discharge guiding unit and the electrode lead.
14 . The battery cell according to claim 13 ,
wherein an adhesive force between the gas discharge guiding unit and the lead film is smaller than at least one of an adhesive force between the adhesive layer and the gas discharge guiding unit or an adhesive force between the adhesive layer and the electrode lead.
15 . The battery cell according to claim 14 ,
wherein the adhesive layer is made of an adhesive tape or an adhesive binder.
16 . The battery cell according to claim 1 ,
wherein the lead film has gas permeability of between 20 Barrer and 60 Barrer at 60° C.
17 . The battery cell according to claim 1 ,
wherein the lead film has a moisture penetration amount of between 0.02 g and 0.2 g for 10 years at 25° C., 50% RH.
18 . The battery cell according to claim 1 ,
wherein the gas discharge guiding unit has gas permeability of 40 Barrer or more at 60° C.
19 . A battery cell manufacturing apparatus for manufacturing the battery cell of claim 1 , comprising:
a sealing tool configured to seal the sealing portion, the electrode lead, and the lead film together, wherein the sealing tool includes a third stepped portion concavely formed in a direction opposite to the sealing portion, and the third stepped portion surrounds the outer surface of the first stepped portion, the second stepped portion is located between the third stepped portion and the outer surface of the first stepped portion.
20 . The battery cell manufacturing apparatus according to claim 19 ,
wherein a first step of the first stepped portion, a second step of the second stepped portion, and a third step of the third stepped portion have a size corresponding to a height of the gas discharge guiding unit, respectively.
21 . (canceled)