KR102761567B1 - Battery cell and battery module including the same - Google Patents

Abstract

According to one embodiment of the present invention, a battery cell comprises: a battery case in which an electrode assembly is mounted in a receiving portion and a sealing portion having a structure in which an outer periphery is sealed; an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding outwardly of the battery case via the sealing portion; and a lead film positioned at a portion corresponding to the sealing portion on at least one of an upper portion and a lower portion of the electrode lead, a gas discharge induction portion being inserted into the lead film, and the battery case comprises a cover portion extending from the sealing portion, the cover portion being positioned on the lead film and protruding outwardly of the battery case.

Description

BATTERY CELL AND BATTERY MODULE INCLUDING THE SAME

The present invention relates to a battery cell and a battery module including the same, and more specifically, to a battery cell having improved insulation performance and gas emission performance and a battery module including the same.

As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing. In particular, secondary batteries are receiving much attention as an energy source for not only mobile devices such as mobile phones, digital cameras, laptops, and wearable devices, but also power devices such as electric bicycles, electric cars, and hybrid electric vehicles.

These secondary batteries are classified into cylindrical batteries and prismatic batteries in which the electrode assembly is built into a cylindrical or prismatic metal can, depending on the shape of the battery case, and pouch-type batteries in which the electrode assembly is built into a pouch-type case made of aluminum laminate sheet. Here, the electrode assembly built into the battery case is a power plant capable of charging and discharging, comprising a positive electrode, an negative electrode, and a separator structure interposed between the positive electrode and the negative electrode, and is classified into a jelly-roll type in which a separator is interposed between long sheet-shaped positive and negative electrodes coated with an active material and wound, and a stack type in which a plurality of positive electrodes and negative electrodes are sequentially stacked while interposing the separator between them.

Among these, pouch-type batteries with a structure in which a stack-type or stack/folding-type electrode assembly is embedded in a pouch-type battery case made of aluminum laminate sheet are gradually increasing in usage due to reasons such as low manufacturing cost, small weight, and easy deformation.

Fig. 1 is a top view of a conventional battery cell. Fig. 2 is a cross-sectional view taken along the a-a' axis in Fig. 1.

Referring to FIGS. 1 and 2, a conventional battery cell (10) includes a battery case (20) in which an electrode assembly (11) is mounted in a receiving portion (21) and includes a sealing portion (25) having a sealed outer periphery. In addition, the battery cell (10) includes an electrode lead (30) that is electrically connected to an electrode tab (15) included in the electrode assembly (11) and protrudes toward the outside of the battery case (20) via the sealing portion (25), and a lead film (40) is positioned between the upper and lower portions of the electrode lead (30) and the sealing portion (25).

However, as the energy density of battery cells has increased recently, there is a problem that the amount of gas generated inside the battery cell is also increasing. In the case of a conventional battery cell (10), since there is no component that can discharge the gas generated inside the battery cell, a venting phenomenon may occur in which the battery case (20) bursts due to gas generation during long-term storage. In addition, a battery cell damaged by the venting phenomenon may have moisture seep inside, which may cause side reactions, and there is a problem that battery performance deterioration and additional gas generation may also occur. Accordingly, there is an increasing need to develop a battery cell with improved external discharge of gas generated inside the battery cell.

The problem to be solved by the present invention is to provide a battery cell having improved insulation performance and gas emission performance and a battery module including the same.

The problems to be solved by the present invention are not limited to the problems described above, and problems not mentioned can be clearly understood by a person having ordinary skill in the art to which the present invention pertains from this specification and the attached drawings.

According to one embodiment of the present invention, a battery cell comprises: a battery case in which an electrode assembly is mounted in a receiving portion and a sealing portion having a structure in which an outer periphery is sealed; an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding outwardly of the battery case via the sealing portion; and a lead film positioned at a portion corresponding to the sealing portion on at least one of an upper portion and a lower portion of the electrode lead, a gas discharge induction portion being inserted into the lead film, and the battery case comprises a cover portion extending from the sealing portion, the cover portion being positioned on the lead film and protruding outwardly of the battery case.

The above cover part can be positioned on the gas discharge induction part.

Based on the direction perpendicular to the protruding direction of the electrode lead, the length of the cover portion may be equal to or greater than the length of the gas discharge induction portion.

Based on the direction perpendicular to the protruding direction of the electrode lead, the length of the cover portion may be equal to or less than the length of the lead film.

The above gas discharge induction part can be located at a part corresponding to the center of the cover part.

Based on the protruding direction of the electrode lead, an end of the cover part may be located outside an end of the lead film.

Based on the protruding direction of the electrode lead, the end of the electrode lead may be located outside the end of the cover part.

The above cover portion may be folded in a direction away from the lead film based on the sealing portion.

The above gas discharge induction portion may extend along the protruding direction of the electrode lead, and an end of the gas discharge induction portion adjacent to the outside of the battery case may be wrapped with the lead film.

An end of the gas discharge induction section adjacent to the inside of the battery case may be exposed inside the battery case.

A gas discharge path can be formed at the interface between the above gas discharge induction unit and the lead film.

The adhesive force between the gas discharge induction portion and the lead film may be less than the adhesive force between the lead film and the electrode lead or the adhesive force between the lead film and the sealing portion.

The above gas discharge inducing member may be a film layer made of at least one of polyimide and polyethylene terephthalate.

The above gas discharge induction unit may be a coating layer made of liquid resin.

The above gas discharge inducing member may further include a getter material including at least one of calcium oxide (CaO), lithium chloride (LiCl), silica (SiO ₂ ), barium oxide (BaO), barium (Ba), and calcium (Ca).

The above gas discharge induction part may be positioned on the electrode lead, and an adhesive layer may be formed between the gas discharge induction part and the electrode lead.

The adhesive force between the gas discharge inducing portion and the lead film may be smaller than the adhesive force between the adhesive layer and the gas discharge inducing portion and the adhesive force between the adhesive layer and the electrode lead.

The above adhesive layer may be made of an adhesive tape or an adhesive binder.

The gas permeability of the above lead film can be 20 to 60 barrer at 60°C.

The moisture permeation amount of the above lead film can be 0.02 g to 0.2 g at 25°C and 50%RH for 10 years.

The gas permeability of the above gas discharge induction unit can be 40 barrer or more at 60°C.

A battery module according to another embodiment of the present invention includes the battery cell described above.

According to embodiments, the present invention provides a battery cell including a cover portion extending from a sealing portion and positioned on a lead film, and a battery module including the same, whereby insulation performance and gas emission performance can be improved.

Specifically, according to one aspect of the present invention, a gas discharge path can be formed at the interface between a gas discharge inducing portion and a lead film, so that gas inside a battery cell can be effectively discharged to the outside while the manufacturing process is relatively easy.

According to another aspect of the present invention, the cover portion may be positioned outside the end of the lead film, so that the insulation performance for the cross-section of the end of the cover portion may be improved. Even when a crack occurs in the gas discharge path due to an increase in the internal pressure of the battery case, the cross-section of the end of the cover portion may be positioned outside the gas discharge path, so that it may not come into contact with the electrolyte leaking outside the gas discharge path, and thus the insulation performance may also be improved.

According to another aspect of the present invention, by controlling the shape of the gas discharge induction part, the gas discharge performance of the gas discharge induction part and the durability and airtightness of the lead film can be controlled. In addition, if necessary, by changing the shape of the gas discharge induction part, the manufacturing process can be simplified and the cost can be reduced.

According to another aspect of the present invention, by setting the gas permeability and moisture penetration amount of the lead film within a predetermined range, it can be more effective in preventing moisture penetration from the outside while discharging gas generated inside the battery cell.

The effects of the present invention are not limited to the effects described above, and effects not mentioned can be clearly understood by a person skilled in the art to which the present invention pertains from this specification and the attached drawings.

Figure 1 is a top view of a conventional battery cell.
Figure 2 is a cross-sectional view taken along the aa' axis in Figure 1.
Figure 3 is a top view of a battery cell according to one embodiment of the present invention.
Figure 4 is a drawing showing an enlarged view of the dashed line area of Figure 3.
Figure 5 is a cross-sectional view taken along the AA' axis of Figure 3.
Figure 6 illustrates various shapes of the gas discharge induction unit.
Figure 7 is a drawing showing an enlarged view of the dashed line area of Figure 5.
Figure 8 is a drawing showing a gas discharge path formed between the interface of the lead film and the gas discharge induction part of Figure 7.
Figure 9 is a drawing showing electrolyte leakage due to a crack that occurred in some of the gas discharge paths of Figure 8.
FIG. 10 is a cross-sectional view taken along the AA' axis of FIG. 3 in a battery cell according to another embodiment of the present invention.
Figure 11 is a drawing showing an enlarged view of the dashed line area of Figure 10.
Figure 12 is a drawing showing a gas discharge path formed between the interface of the lead film and the gas discharge induction part of Figure 11.
Figure 13 is a drawing showing electrolyte leakage due to a crack that occurred in some of the gas discharge paths of Figure 12.
Fig. 14 is a cross-sectional view taken along the a-a' axis of Fig. 1 according to a comparative example.
Figure 15 is a drawing that enlarges the dashed line area of Figure 14 and shows electrolyte leakage due to cracks that occurred in some of the gas discharge paths of Figure 14.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein.

In order to clearly explain the present invention, parts irrelevant to the description are omitted, and the same reference numerals are used for identical or similar components throughout the specification.

In addition, the size and thickness of each component shown in the drawing are arbitrarily shown for the convenience of explanation, so the present invention is not necessarily limited to what is shown. In the drawing, the thickness is shown enlarged to clearly express several layers and regions. And in the drawing, the thickness of some layers and regions is shown exaggeratedly for the convenience of explanation.

Additionally, throughout the specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

Additionally, throughout the specification, when we say "in plan", we mean when the target portion is viewed from above, and when we say "in cross section", we mean when the target portion is viewed from the side in a cross-section cut vertically.

Hereinafter, a battery cell according to an embodiment of the present invention will be described. However, the description will be based on one end of the battery cell, but it is not necessarily limited thereto, and the same or similar content may be described for the opposite end of the battery cell.

Figure 3 is a top view of a battery cell according to one embodiment of the present invention.

According to one embodiment of the present invention, a battery cell (100) includes a battery case (200) in which an electrode assembly (110) is mounted in a receiving portion (210) and has a sealing portion (250) having a sealed outer periphery; an electrode lead (300) electrically connected to an electrode tab (150) included in the electrode assembly (110) and protruding in an outer direction of the battery case (200) via the sealing portion (250); and a lead film (400) positioned at a portion corresponding to the sealing portion (250) on at least one of the upper and lower portions of the electrode lead (300). For example, the battery cell (100) may have a long side in a direction along the X-axis, a short side in a direction along the Y-axis, and a thickness in the Z-axis direction smaller than the length of the X-axis or Y-axis, thereby being an approximately rectangular plate-shaped cell. An electrode lead (300) may be formed on the short side of the battery cell (100). This battery cell (100) is an efficient structure for increasing energy density by stacking multiple battery cells (100) face to face by integrating them in the Z-axis direction.

The electrode assembly (110) may be formed in a jelly-roll type (rolled type), a stack type (laminated type), or a composite type (stack/folded type) structure. More specifically, the electrode assembly (110) may be formed of a positive electrode, a negative electrode, and a separator disposed therebetween.

The electrode lead (300) is electrically connected to the electrode tab (150) included in the electrode assembly (110) and protrudes toward the outside of the battery case (200) via the sealing portion (250). In addition, the lead film (400) is positioned at a portion corresponding to the sealing portion (250) on at least one of the upper and lower portions of the electrode lead (300). Accordingly, the lead film (400) can prevent a short circuit from occurring in the electrode lead (300) when heat-sealing or press-sealing is performed together with the sealing portion (250), while also improving the sealing property of the sealing portion (250) and the electrode lead (300).

Referring to FIG. 3, the lead film (400) may have a wider width than the electrode lead (300). Here, the width of the lead film (400) means the maximum value of the distance between one end and the other end of the lead film (400) in a direction (Y-axis direction) orthogonal to the protrusion direction (X-axis direction) of the electrode lead (300), and the width of the electrode lead (300) means the maximum value of the distance between one end and the other end of the electrode lead (300) in a direction orthogonal to the protrusion direction of the electrode lead (300).

The lead film (400) may have a length greater than the length of the sealing portion (250) based on the protruding direction of the electrode lead (300) and may have a length less than the length of the electrode lead (300). Here, the length of the lead film (400) means the maximum value of the distance between one end and the other end of the lead film (400) in the protruding direction of the electrode lead (300). The length of the sealing portion (250) means the maximum value of the distance between one end and the other end of the sealing portion (250) in the protruding direction of the electrode lead (300). The length of the electrode lead (300) means the maximum value of the distance between one end and the other end of the electrode lead (300) in the protruding direction of the electrode lead (300). Accordingly, the lead film (400) can prevent the side of the electrode lead (300) from being exposed to the outside without interfering with the electrical connection of the electrode lead (300).

The battery case (200) may be a laminate sheet including a resin layer and a metal layer. More specifically, the battery case (200) may be made of a laminate sheet and may be composed of an outer resin layer forming the outermost layer, a barrier metal layer preventing penetration of a material, and an inner resin layer for sealing. As an example, the barrier metal layer may be made of an aluminum material.

Here, the battery case (200) can be manufactured by cutting the laminate sheet according to a predetermined shape, and the corners of the battery case (200) can have cross sections of the outer resin layer, the barrier metal layer, and the inner resin layer exposed to the outside. Here, the cutting method can be applied by laser cutting, knife cutting, and mold punching, but is not limited thereto, and a cutting method generally applied when cutting a laminate sheet can also be included in this embodiment.

However, in the battery case (200), there is a problem that the blocking metal layer exposed at the corner of the battery case (200) may form an electric circuit and lead to a fire if it comes into contact with an external substance or an electrolyte. Accordingly, in the present embodiment, it is necessary to secure insulation for the blocking metal layer exposed at the corner of the battery case (200).

Fig. 4 is a drawing showing an enlarged view of the dashed line area of Fig. 3. Fig. 5 is a cross-sectional view taken along the A-A' axis of Fig. 3.

Referring to FIGS. 4 and 5, in the present embodiment, a gas discharge induction part (450) is inserted into a lead film (400), and the battery case (200) may include a cover part (270) extending from a sealing part (250).

Here, the sealing portion (250) and the cover portion (270) may be integrated with each other. More specifically, by heat fusing or press fusing between the storage portion (210) and the cover portion (270) in the battery case (200), the sealing portion (250) may be formed between the storage portion (210) and the cover portion (270).

In addition, the cover portion (270) may extend from the sealing portion (250) and protrude in the outer direction of the battery case (200). More specifically, the cover portion (270) may extend from the sealing portion (250) positioned on the lead film (400). That is, the cover portion (270) may be positioned on the lead film (400). Here, with respect to the sealing portion (250), the cover portion (270) may extend in the same direction as the direction in which the lead film (400) protrudes in the outer direction of the battery case (200).

In addition, the cover part (270) may be positioned on the gas discharge induction part (450). More specifically, the cover part (270) may be positioned on the gas discharge induction part (450) with the lead film (400) interposed therebetween. In other words, the cover part (270) may be positioned at a portion of the lead film (400) corresponding to the portion where the gas discharge induction part (450) is positioned. That is, the cover part (270) may cover the portion of the lead film (400) where the gas discharge induction part (450) is positioned. When cutting the battery case (200), the cover part (270) may be cut so that it is longer in the X-axis direction than the sealing part (250), thereby providing a cover part (270) that can cover the portion where the gas discharge induction part (450) is positioned.

For example, the gas discharge induction unit (450) may be positioned at a portion corresponding to the center of the cover unit (270). In other words, the center line of the gas discharge induction unit (450) and the center line of the cover unit (270) may coincide with each other.

According to the above configuration, in this embodiment, the cover part (270) can be positioned on the gas discharge induction part (450) of the lead film (400), so as to cover a portion of the gas discharge path formed by the lead film (400) and the gas discharge induction part (450) that is exposed to the outside of the battery case (200). In other words, the cross-section of the battery case (200) can cover the gas discharge path portion.

Referring to FIG. 4, the length of the cover part (270) may be equal to or greater than the length of the gas discharge induction part (450) in the direction perpendicular to the protrusion direction of the electrode lead (300). Here, the length of the cover part (270) means the maximum value of the distance between one end and the other end of the cover part (270) in the direction perpendicular to the protrusion direction of the electrode lead (300). The length of the gas discharge induction part (450) means the maximum value of the distance between one end and the other end of the gas discharge induction part (450) in the direction perpendicular to the protrusion direction of the electrode lead (300).

Accordingly, the cover part (270) can cover the entire portion of the gas discharge induction part (450) located on the outside of the battery case (200) in the lead film (400). That is, the entire portion of the gas discharge path formed by the lead film (400) and the gas discharge induction part (450) that is exposed on the outside of the battery case (200) can be effectively covered.

For example, based on the direction perpendicular to the protrusion direction of the electrode lead (300), the length of the cover portion (270) may be equal to or smaller than the length of the lead film (400). Here, the length of the lead film (400) means the maximum value of the distance between one end and the other end of the lead film (400) in the direction perpendicular to the protrusion direction of the electrode lead (300). That is, the cover portion (270) may cover part or all of the portion where the lead film (400) is positioned.

According to the above configuration, in this embodiment, the cover part (270) can have a similar size to the lead film (400), so as to effectively cover the part where the gas discharge induction part (450) is located, while increasing the space efficiency of the battery cell (100).

However, the size of the cover part (270) is not limited thereto, and as described above, if it is of a size that can cover the part where the gas discharge induction part (450) is located, it can be included in this embodiment.

Referring to FIGS. 4 and 5, based on the protruding direction of the electrode lead (300), the end of the cover portion (270) may be located outside the end of the lead film (400). In other words, the end of the cover portion (270) may extend from the sealing portion (250) and may extend in a direction toward the outside than the end of the lead film (400).

More specifically, the cover part (270) may be bent in a direction (Z-axis direction) away from the lead film (400) with respect to the sealing part (250). Here, the angle at which the cover part (270) is bent with respect to the sealing part (250) may be an angle generated as the sealing part (250) is fused. However, the angle at which the cover part (270) is bent with respect to the sealing part (250) may be adjusted to be smaller or larger than the angle generated as the sealing part (250) is fused, as needed.

Accordingly, in the present embodiment, the cover part (270) may be positioned outside the end of the lead film (400), so that the insulation performance for the cross-section of the end of the cover part (270) may be improved. That is, even when a crack occurs in the gas discharge path due to an increase in the internal pressure of the battery case (200), the cross-section of the end of the cover part (270) may be positioned outside the gas discharge path, so that it may not come into contact with the electrolyte leaking out of the gas discharge path, and thus the insulation performance may also be improved. In other words, the battery case (200) in the gas discharge path portion may be cut long so that the cut surface of the battery case (200) sufficiently covers the gas discharge path, so that even if the electrolyte leaks, the insulating metal layer exposed to the cut surface of the battery case (200) and the leaked electrolyte will not come into contact, so that an electric circuit is not formed, so that the insulation performance may be maintained.

In addition, based on the protrusion direction of the electrode lead (300), the end of the electrode lead (300) may be located outside the end of the cover part (270). In other words, the end of the cover part (270) may extend from the sealing part (250) and may extend shorter than the end of the electrode lead (300).

Accordingly, in this embodiment, the end of the electrode lead (300) is located outside the end of the cover part (270), so that the cover part (270) can improve insulation performance while not interfering with electrical connection between the electrode lead (300) and other components.

Referring to FIGS. 4 and 5, the gas discharge induction unit (450) may extend along the protruding direction of the electrode lead (300). More specifically, in the gas discharge induction unit (450), an end of the gas discharge induction unit (450) adjacent to the outside of the battery case (200) may be wrapped with a lead film (400). In other words, an end of the gas discharge induction unit (450) adjacent to the outside of the battery case (200) may not be exposed to the outside of the battery case (200).

In addition, an end of the gas discharge induction unit (450) adjacent to the inside of the battery case (200) may be exposed inside the battery case (200). In other words, an end of the gas discharge induction unit (450) adjacent to the inside of the battery case (200) may be positioned on the same vertical line as an end of the lead film (400), or may be positioned inside the battery case (200) compared to an end of the lead film (400).

Accordingly, in the lead film (400), one end of the gas discharge induction part (450) adjacent to the outside of the battery case (200) is not exposed to the outside of the battery case (200), so that the sealing power of the battery case (200) by the lead film (400) and the sealing part (250) can be improved. In addition, in the lead film (400), one end of the gas discharge induction part (450) adjacent to the inside of the battery case (200) is exposed to the inside of the battery case (200), so that the gas discharge path formed by the gas discharge induction part (450) can easily introduce gas generated within the battery cell (100) and effectively discharge it toward the outside.

Referring further to FIG. 5, the thickness (H, height in the Z-axis direction) of the lead film (400) on the upper surface of the gas discharge induction unit (450) may be 100 ㎛ to 300 ㎛, or 100 ㎛ to 200 ㎛. When the thickness (H) of the lead film (400) satisfies the above-described range, the gas inside the battery case (200) may be discharged more easily to the outside.

Also, referring to FIG. 5, based on the protruding direction of the electrode lead (300), the width (W) of the lead film (400) covering the front of the gas discharge induction unit (450) may be 2 mm or more, or 2 mm to 3 mm. When the width (W) of the lead film (400) satisfies the above-described range, the lead film (400) can be prevented from being torn as much as possible during the process of discharging gas generated inside the battery case (200) to the outside.

In addition, the thickness (D) of the gas discharge induction part (450) may be 50 ㎛ to 150 ㎛. When the thickness of the gas discharge induction part (450) satisfies the above-described range, the gas inside the battery case (200) may be discharged more easily to the outside. Fig. 6 illustrates various shapes of the gas discharge induction part. The gas discharge induction part (450) may be formed in a predetermined pattern in order to discharge the gas inside the battery case (200).

For example, the gas discharge induction part (450) may have a rectangular shape extending along the protruding direction of the electrode lead (300), as shown in Fig. 4. However, it is not limited thereto, and the gas discharge induction part (450) may have various shapes, such as a circle as shown in Fig. 6 (a), an oval as shown in Fig. 6 (b), and other linear or curved shapes.

As another example, the gas discharge induction unit (450) may include a first gas discharge induction unit (450a) extending along the protruding direction of the electrode lead (300) as shown in (c) of FIG. 6 and a second gas discharge induction unit (450b) extending in a direction perpendicular to the protruding direction of the electrode lead (300). In particular, the first gas discharge induction unit (450a) and the second gas discharge induction unit (450b) may be connected to each other. Here, the second gas discharge induction unit (450b) may be located on the inside of the lead film (400) outside the sealing unit (250) with respect to the sealing unit (250), as shown in (c) of FIG. 6, or may be located on the outside of the lead film (400) with respect to the sealing unit (250) with respect to the sealing unit (250) with respect to the sealing unit (250) as shown in (d) of FIG. Alternatively, the second gas discharge induction unit (450b) may be positioned both on the outside of the lead film (400) and on the inside of the lead film (400) based on the sealing unit (250), as shown in (e) of FIG. 6. However, the shape of the gas discharge induction unit (450) is not limited to the above-described content, and may be inserted into the lead film (400) in an appropriate shape. Accordingly, by adjusting the shape of the gas discharge induction unit (450) inserted into the lead film (400), the gas discharge performance of the gas discharge induction unit (450) and the durability and airtightness of the lead film (400) can be controlled. In addition, if necessary, the shape of the gas discharge induction unit (450) can be changed to simplify the manufacturing process and reduce costs.

For example, the gas discharge induction unit (450) may be included only in one lead film (400) as shown in Fig. 4. As another example, the gas discharge induction unit (450) may be inserted in multiple numbers in the lead film (400) and positioned spaced apart from each other.

Accordingly, by controlling the number of gas discharge inducing parts (450) inserted into the lead film (400), the gas discharge performance of the gas discharge inducing parts (450) and the durability and airtightness of the lead film (400) can be controlled. In addition, if necessary, the number of gas discharge inducing parts (450) can be minimized to simplify the manufacturing process and reduce costs.

Fig. 7 is a drawing showing an enlarged view of the dashed line area of Fig. 5. Fig. 8 is a drawing showing a gas discharge path formed between the interface of the lead film and the gas discharge induction part of Fig. 7. Fig. 9 is a drawing showing electrolyte leakage due to a crack that occurred in a part of the gas discharge path of Fig. 8.

Referring to FIGS. 7 and 8, in the present embodiment, a gas discharge path may be formed at the interface between the gas discharge inducing member (450) and the lead film (400). More specifically, as shown in FIGS. 7 and 8, the gas discharge path may mean a space in which at least a portion of the interface between the gas discharge inducing member (450) and the lead film (400) is separated from each other by the pressure of the gas generated in the battery case (200). In FIG. 8, the gas movement path is indicated by a dotted arrow. That is, as in the direction of the dotted arrow in FIG. 8, the gas discharge path may mean a path in which gas flows in and is discharged to the outside through a space that is separated from each other at the interface between the gas discharge inducing member (450) and the lead film (400).

Here, the adhesive force between the gas discharge induction unit (450) and the lead film (400) may be lower than the adhesive force between the lead film (400) and the electrode lead (300) or the adhesive force between the lead film (400) and the sealing unit (250). More specifically, when the pressure inside the battery case (200) increases due to the gas generated in the battery cell (100), the adhesive force of the interface between the gas discharge induction unit (450) and the lead film (400) is relatively lower than the adhesive force between the lead film (400) and other components, so that at least a portion of the interface between the gas discharge induction unit (450) and the lead film (400) may be separated from each other due to the pressure of the gas generated in the battery cell (100), as shown in FIG. 8.

That is, in this embodiment, due to the relatively low adhesive force between the gas discharge induction part (450) and the lead film (400), when the gas discharge induction part (450) and the lead film (400) are peeled off, gas inside the battery cell (100) can flow into the gas discharge passage formed at the interface between the gas discharge induction part (450) and the lead film (400), and the gas can move along this gas discharge passage and ultimately be discharged through the lead film (400). The gas that flows into the gas discharge passage can be discharged toward the outside depending on the pressure difference with the outside.

However, the above gas discharge path may include not only the case where the interface between the upper surface of the gas discharge induction unit (450) and the lead film (400) and the interface between the lower surface of the gas discharge induction unit (450) and the lead film (400) are all spaced apart as shown in FIG. 8, but also the case where the interface between the upper surface of the gas discharge induction unit (450) and the lead film (400) or the interface between the lower surface of the gas discharge induction unit (450) and the lead film (400) are spaced apart.

For example, the gas discharge induction unit (450) may be a film layer made of at least one of polyimide (PI) and polyethylene terephthalate (PET). As another example, the gas discharge induction unit (450) may be a coating layer made of liquid resin. However, the shape of the gas discharge induction unit (450) or the material constituting the same is not limited thereto, and any shape or material that can make the adhesive force of the interface between the gas discharge induction unit (450) and the lead film (400) relatively lower than the adhesive force between the lead film (400) and other components may be included in the present embodiment.

Accordingly, the battery cell according to the present embodiment can form a gas discharge path at the interface between the gas discharge inducing part (450) and the lead film (400) through a relatively low adhesive force between the gas discharge inducing part (450) and the lead film (400), so that the manufacturing process is relatively easy while the gas inside the battery cell (100) can be effectively discharged to the outside.

Also, referring back to FIGS. 4 and 5, one end of the gas discharge induction part (450) may be located further inward than the inner surface of the sealing part (250) based on the protruding direction of the electrode lead (300). In this specification, the inner surface of the sealing part (250) means an end of the sealing part (250) adjacent to the inside of the battery case (200), and being located further inward than the inner surface of the sealing part (250) means being located closer to the inside of the battery case (200) than the inner surface of the sealing part (250). When one end of the gas discharge induction part (450) is located further inward than the inner surface of the sealing part (250), gas may be more easily introduced into the gas discharge induction part (450) without being interfered with by the sealing part (250).

In addition, based on the protruding direction of the electrode lead (300), the other end of the gas discharge induction part (450) may be located further outside than the outer surface of the sealing part (250). In this specification, the outer surface of the sealing part (250) means an end of the sealing part (250) adjacent to the outside of the battery case (200), and being located further outside than the outer surface of the sealing part (250) means being located further outside the battery case (200) than the outer surface of the sealing part (250). For example, a gap (P) is provided between the outer surface of the sealing part (250) and the other end of the gas discharge induction part (450). In this way, when the other end of the gas discharge induction part (450) is located further outside than the outer surface of the sealing part (250), gas introduced into the gas discharge induction part (450) can be more easily discharged to the outside. For example, since the other end of the gas discharge induction unit (450) is not interfered with by the sealing unit (250), gas flowing into the gas discharge induction unit (450) can be discharged more easily to the outside.

Accordingly, the gas generated inside the battery cell (100) is discharged toward the gas discharge induction unit (450), and the gas that has entered the gas discharge induction unit (450) can be easily discharged toward the outside as shown in FIG. 8. In addition, the amount of gas discharged outside the battery cell (100) can also increase. In this way, the gas generated inside the battery case (200) can be easily introduced into the gas discharge induction unit (450) while being more easily discharged outside the gas discharge induction unit (450).

In addition, as illustrated in FIG. 8, gas introduced into the gas discharge induction unit (450) can be particularly easily discharged along the Z-axis direction through the lead film (400) on the gas discharge induction unit (450). For example, when the other end of the gas discharge induction unit (450) is located outside the outer surface of the sealing unit (250), gas introduced into the gas discharge induction unit (450) can be discharged along the Z-axis direction in the portion of the lead film (400) between the other end of the gas discharge induction unit (450) and the outer surface of the sealing unit (250). As mentioned above, the thickness (H) of the lead film (400) on the upper surface of the gas discharge induction unit (450) may be 100 ㎛ to 300 ㎛, and the width (W) of the lead film (400) covering the front surface of the gas discharge induction unit (450) based on the protruding direction of the electrode lead (300) may be 2 mm or more, or 2 mm to 3 mm. When the other end of the gas discharge induction unit (450) is positioned outside the outer surface of the sealing unit (250) as described above, the gas can be discharged through a portion of the lead film (400) that is located in the Z-axis direction, which is a relatively thin portion. Therefore, gas discharge is easier. In addition, since gas discharge is not smooth when the gas discharge path is completely blocked by the sealing portion (250) when gas discharge occurs, as in the example, by leaving a gap (P) between the outer surface of the sealing portion (250) and the other end of the gas discharge induction portion (450), there is an effect of smoothing gas discharge.

Referring to FIG. 9, in the present embodiment, a gas discharge path formed at the interface between the gas discharge inducing portion (450) and the lead film (400) may cause a crack to form in a portion of the lead film (400) after a certain period of time. More specifically, if gas inside the battery cell (100) continues to flow in and out through the gas discharge path, an end portion of the lead film (400) adjacent to the outside of the battery case (200) may become structurally vulnerable. Even if the width (W) of the lead film (400) covering the front of the gas discharge inducing portion (450) is set to 2 mm or more to prevent the lead film (400) from being torn, cracks may form in the lead film as the battery cell (100) continues to be used. In such a case, the electrolyte (50) inside the battery cell (100) may leak to the outside through the crack.

Here, referring to FIGS. 7 to 9, in the battery cell (100) according to the present embodiment, the cover part (270) may be positioned outside the end of the lead film (400), and the end of the cover part (270) may be positioned outside the end of the gas discharge path. Accordingly, in the present embodiment, even if a crack occurs and the electrolyte (50) leaks, the cross-section of the end of the cover part (270) may not come into contact with the electrolyte leaking outside the gas discharge path.

As illustrated in Fig. 9, even if the electrolyte (50) leaks through a crack, the leaked electrolyte is located on the inner resin layer side of the cover part (270) and has difficulty reaching the barrier metal layer exposed at the cross-section of the end of the cover part (270). That is, the barrier metal layer exposed at the cross-section of the end of the cover part (270) may not come into contact with the electrolyte leaking outside the gas discharge path, thereby preventing an electric circuit from being formed between the barrier metal layer and the electrolyte, and thus the insulation performance and safety may also be improved.

In addition, the gas exhaust induction unit (450) may further include a material having a function of absorbing or adsorbing moisture flowing in from the outside or hydrofluoric acid generated internally. More specifically, the gas exhaust induction unit (450) may further include a getter material. Here, the getter material may mean a material that can perform vacuum exhaust by utilizing the action of gas being adsorbed by a chemically activated metal film. As an example, the getter material may include at least one of calcium oxide (CaO), lithium chloride (LiCl), silica (SiO ₂ ), barium oxide (BaO), barium (Ba), and calcium (Ca). As another example, the getter material may have a structure of a metal organic framework (MOF). However, the getter material is not limited thereto, and may include all types of materials generally classified as getter materials.

Accordingly, in the present embodiment, the gas discharge induction unit (450) further includes a material capable of absorbing or adsorbing moisture or hydrofluoric acid, so that the gas discharge induction unit (450) can further minimize the infiltration of moisture or hydrofluoric acid flowing from the outside of the battery cell (100) into the inside of the battery cell (100), while more easily discharging gas generated inside the battery cell (100) to the outside.

In one embodiment of the present invention, the gas permeability of the gas discharge induction unit (450) may be 40 barrer or more at 60° C. For example, the carbon dioxide permeability of the gas discharge induction unit (450) may satisfy the above-described range.

For example, the gas discharge induction unit (450) may include at least one material from among a polyolefin series, a fluorine series, and a porous ceramic series that satisfy the above-described gas permeability value. The polyolefin series material may include at least one material selected from the group consisting of polypropylene, polyethylene, and polyvinyldifluoride (PVDF). The fluorine series material may include at least one material selected from the group consisting of polytetrafluoroethylene and polyvinylidene fluoride.

In one embodiment of the present invention, the gas permeability of the lead film (400) may be 20 to 60 barrer, or 30 to 40 barrer at 60° C. For example, the carbon dioxide permeability of the lead film (400) may satisfy the above-described range. In addition, based on a thickness (H) of 200 ㎛ of the lead film (400), the gas permeability may satisfy the above-described range at 60° C. When the gas permeability of the lead film (400) satisfies the above-described range, the gas generated inside the battery cell may be discharged more effectively.

In this specification, gas permeability can be measured by ASTM F2476-20.

In one embodiment of the present invention, the moisture penetration amount of the lead film (400) may be 0.02 g to 0.2 g, or 0.02 g to 0.04 g, or 0.06 g or 0.15 g at 25° C. and 50% RH for 10 years. When the moisture penetration amount of the lead film (400) satisfies the above-described range, it may be more effective to prevent the penetration of moisture flowing in from the lead film (400).

In one embodiment of the present invention, the lead film (400) may have a gas permeability of 20 to 60 barrer at 60° C. and a moisture permeability of 0.02 to 0.2 g at 25° C. and 50% RH for 10 years. When the gas permeability and moisture permeability of the lead film (400) satisfy the above-described ranges, it may be more effective in preventing moisture permeation from the outside while discharging gas generated inside the battery cell (100).

The moisture penetration amount of the above lead film (400) can be measured by adopting the ASTM F 1249 method. At this time, the measurement can be made using equipment officially certified by MCOON.

In one embodiment of the present invention, the lead film (400) may be formed of an adhesive composition comprising at least one of a polyolefin series material, epoxy, and polyvinyl chloride (PVC). The polyolefin series material may be polyethylene (PE), polypropylene (PP), or the like. For example, the lead film (400) may be polyethylene, polypropylene, or the like that satisfies the above-described gas permeability and/or moisture penetration amount values.

In addition, the lead film (400) is made of the material described above, so that it can maintain the sealing of the battery cell (100) and also prevent leakage of the internal electrolyte.

Hereinafter, a battery cell according to another embodiment of the present invention will be described. However, the battery cell according to this embodiment can be described mostly in the same way as the battery cell (100) described above, and the description will focus on the differences between the gas discharge induction unit (450) and the battery cell (100).

FIG. 10 is a cross-sectional view taken along the A-A' axis of FIG. 3 in a battery cell according to another embodiment of the present invention.

Referring to FIGS. 4 and 10, in the present embodiment, unlike FIG. 5, the gas discharge induction unit (450') may be positioned on the electrode lead (300'). More specifically, a separate lead film (400') may not be positioned between the gas discharge induction unit (450') and the electrode lead (300'). That is, the gas discharge induction unit (450') may be inserted into one surface of the lead film (400') adjacent to the electrode lead (300') and may be positioned adjacent to the electrode lead (300'). In other words, the present embodiment may have a structure in which the lead film (400') wraps around the outer surface of the gas discharge induction unit (450') after the gas discharge induction unit (450') is attached or fixed on the electrode lead (300').

Accordingly, since the gas discharge induction part (450') is positioned adjacent to the electrode lead (300'), the thickness of the lead film (400') surrounding the gas discharge induction part (450') can also be relatively reduced, which has the advantage of reducing the manufacturing cost and facilitating the manufacturing process.

In addition, an adhesive layer (470') may be formed between the gas discharge induction unit (450') and the electrode lead (300'). Here, the adhesive layer (470') may extend along the interface between the gas discharge induction unit (450') and the electrode lead (300'). At this time, the adhesive layer (470') may be formed on the entirety or part of the interface between the gas discharge induction unit (450') and the electrode lead (300').

For example, the adhesive layer (470') may be made of an adhesive tape or an adhesive binder. However, it is not limited thereto, and any material having an adhesive performance capable of fixing the gas discharge induction unit (450') and the electrode lead (300') to each other may be applied without limitation.

Accordingly, the gas discharge induction part (450') can be stably fixed to the electrode lead (300') by the adhesive layer (470'). That is, an adhesive layer (470') having a relatively high adhesive strength is formed between the gas discharge induction part (450') and the electrode lead (300'), so that peeling due to an increase in the internal pressure of the battery cell (100) can be prevented, and the sealing strength of the battery cell (100) can also be further improved.

Fig. 11 is a drawing showing an enlarged view of the dashed line area of Fig. 10. Fig. 12 is a drawing showing a gas discharge path formed between the interface of the lead film and the gas discharge induction part of Fig. 11. Fig. 13 is a drawing showing electrolyte leakage due to a crack that occurred in a part of the gas discharge path of Fig. 12.

Referring to FIGS. 11 to 13, in the present embodiment, similarly to FIGS. 7 to 9, a gas discharge path may be formed at the interface between the gas discharge inducing member (450') and the lead film (400'). However, in the present embodiment, unlike FIGS. 7 to 9, the gas discharge inducing member (450') is positioned adjacent to the electrode lead (300'), and an adhesive layer (470') is formed between the gas discharge inducing member (450') and the electrode lead (300'), so that a gas discharge path may not be formed at the interface between the gas discharge inducing member (450') and the electrode lead (300'). The gas movement path in FIG. 12 is indicated by a dotted arrow.

More specifically, in the present embodiment, the adhesive force between the gas discharge induction unit (450') and the lead film (400') may be less than the adhesive force between the adhesive layer (470') and the gas discharge induction unit (450') and/or the adhesive force between the adhesive layer (470') and the electrode lead (300').

More specifically, in the present embodiment, when the pressure inside the battery cell (100) increases, the adhesive force at the interface between the gas discharge induction part (450') and the lead film (400') is relatively smaller than the adhesive force between the lead film (400') and other components, so that at least a portion of the interface between the gas discharge induction part (450') and the lead film (400') may be separated from each other by the pressure inside the battery cell (100), as shown in FIG. 12.

In addition, in the present embodiment, the adhesive force of the interface between the gas discharge induction part (450') and the lead film (400') is smaller than the adhesive force between the gas discharge induction part (450') and/or the adhesive force between the adhesive layer (470') and the electrode lead (300'), so that the interface between the gas discharge induction part (450') and the electrode lead (400') can be prevented from being peeled off when the internal pressure of the battery cell (100) increases.

That is, in this embodiment, only the interface between the gas discharge inducing part (450') and the lead film (400') can be peeled off to form a gas discharge path, thereby increasing the sealing strength of the battery cell (100) while maintaining the gas discharge performance by the gas discharge path. In addition, according to the high sealing strength, the vent pressure when the gas generated inside the battery cell (100) is discharged to the outside can also be increased, and safety can also be further improved.

In addition, in this embodiment, the gas discharge path can be formed only at the interface between the gas discharge induction part (450') and the lead film (400'), and the gas discharge path can induce the electrolyte (50) inside the battery cell (100) to be discharged in the direction in which the cover part (270) is located, even if a crack occurs as shown in FIG. 13. That is, the insulation performance and safety can also be further improved accordingly.

Hereinafter, a battery cell according to a comparative example of the present invention will be described. In the case of the comparative example, it will be described by comparison with the embodiment according to FIGS. 3 to 9, but the embodiment according to FIGS. 10 to 13 can also be described by comparison in the same manner.

Fig. 14 is a cross-sectional view taken along the a-a' axis of Fig. 1 according to a comparative example. Fig. 15 is a drawing showing an enlarged area of the dashed line of Fig. 14, and showing that electrolyte leaks due to a crack that occurs in a part of a gas discharge path of Fig. 14.

Referring to FIGS. 14 and 15, a battery cell (10) according to a comparative example is described. The comparative example can be described in the same manner as the battery cell (10) of FIGS. 1 and 2, except that the configuration includes a gas discharge induction unit (45) as in the present embodiment. Hereinafter, the description will be centered on the gas discharge induction unit (45).

Referring to FIG. 14, the battery cell (10) according to the comparative example has a sealing portion (25) formed on a lead film (40) where a gas discharge induction portion (45) is located, and unlike FIGS. 3 to 9, a separate component extending from an end of the sealing portion (25) is not included. That is, a cross-section of the sealing portion (25) may be exposed to the outside, and in particular, the cross-section of the sealing portion (25) may be located on a gas discharge path formed by the lead film (40) and the gas discharge induction portion (45).

Referring to FIG. 15, even in the case of the battery cell (10) according to the comparative example, cracks may occur in a portion of the lead film (40) as a certain amount of time passes, as shown in FIG. 9, and the electrolyte (50) inside the battery cell (10) may leak to the outside through the cracks.

However, in the case of the battery cell (10) according to the comparative example, the cross-section of the sealing portion (25) is located on the gas discharge path formed by the lead film (40) and the gas discharge induction portion (45), so that the cross-section of the sealing portion (25) and the electrolyte leaking out of the gas discharge path can come into contact with each other as shown in FIG. 15. That is, the barrier metal layer exposed on the cross-section of the sealing portion (25) can come into contact with the electrolyte leaking out of the gas discharge path, so that an electric circuit is formed between the barrier metal layer and the electrolyte, and thus a fire may occur, thereby significantly reducing safety.

In contrast, referring to FIGS. 3 to 9, in the battery cell (100) according to the present embodiment, the cover part (270) extends from the sealing part (250) located on the gas discharge induction part (450), and the end of the cover part (270) may be located outside the end of the gas discharge path. That is, unlike the comparative example, in the present embodiment, even if a crack occurs in a part of the lead film (400), the electrolyte leaking from the crack may not come into contact with the end of the cover part (270), so that an electric circuit between the end of the cover part (270) and the electrolyte may be prevented from being formed, and thus, the insulation performance and safety may also be improved.

A battery module according to another embodiment of the present invention includes the battery cell described above. Meanwhile, one or more battery modules according to the present embodiment may be packaged within a pack case to form a battery pack.

The battery module described above and the battery pack including it can be applied to various devices. Such devices can be applied to means of transportation such as electric bicycles, electric cars, and hybrid cars, but the present invention is not limited thereto and can be applied to various devices that can use the battery module and the battery pack including it, and this also falls within the scope of the present invention.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

100: Battery cell
110: Electrode assembly
200: Battery Case
210: Storage compartment
250: Sealing part
270: Cover part
300: Electrode Lead
400: Lead Film
450: Gas discharge induction unit

Claims (22)

A battery case including a sealing portion having a structure in which an electrode assembly is mounted in a receiving portion and the outer periphery is sealed;
An electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding toward the outside of the battery case through the sealing portion; and
At least one of the upper and lower portions of the electrode lead comprises a lead film positioned at a portion corresponding to the sealing portion,
A gas discharge induction part is inserted into the above lead film,
The above battery case includes a cover portion extending from the sealing portion,
The above cover portion is positioned on the lead film and protrudes in the outer direction of the battery case,
A battery cell in which an end of the cover part is located outside an end of the lead film based on the protruding direction of the electrode lead. In paragraph 1,
The above cover part is a battery cell located on the gas discharge induction part. In paragraph 2,
The above gas discharge induction part is a battery cell located at a part corresponding to the center of the cover part. In paragraph 2,
A battery cell wherein the length of the cover portion is equal to or greater than the length of the gas discharge induction portion, based on the direction perpendicular to the protruding direction of the electrode lead. In Article 4,
A battery cell wherein the length of the cover portion is equal to or less than the length of the lead film, based on the direction perpendicular to the protruding direction of the electrode lead. delete In paragraph 1,
A battery cell wherein, based on the protruding direction of the electrode lead, the end of the electrode lead is located outside the end of the cover part. In paragraph 1,
A battery cell in which the cover portion is bent in a direction away from the lead film based on the sealing portion. In paragraph 1,
A battery cell in which the gas discharge induction portion extends along the protruding direction of the electrode lead, and an end of the gas discharge induction portion adjacent to the outside of the battery case is wrapped with the lead film. In Article 9,
The end of the gas discharge induction section adjacent to the inside of the battery case is a battery cell exposed inside the battery case. In paragraph 1,
A battery cell in which a gas discharge path is formed at the interface between the gas discharge inducing portion and the lead film. In Article 11,
A battery cell in which the adhesive force between the gas discharge induction part and the lead film is smaller than the adhesive force between the lead film and the electrode lead or the adhesive force between the lead film and the sealing part. In Article 12,
A battery cell in which the gas discharge inducing portion is a film layer made of at least one of polyimide and polyethylene terephthalate. In Article 12,
The above gas discharge induction unit is a battery cell having a coating layer made of liquid resin. In Article 12,
A battery cell wherein the gas emission inducing portion further includes a getter material including at least one of calcium oxide (CaO), lithium chloride (LiCl), silica (SiO ₂ ), barium oxide (BaO), barium (Ba), and calcium (Ca). In paragraph 1,
A battery cell in which the gas discharge induction part is positioned on the electrode lead, and an adhesive layer is formed between the gas discharge induction part and the electrode lead. In Article 16,
A battery cell wherein the adhesive force between the gas discharge inducing part and the lead film is smaller than at least one of the adhesive force between the adhesive layer and the gas discharge inducing part and the adhesive force between the adhesive layer and the electrode lead. In Article 17,
A battery cell wherein the above adhesive layer is made of an adhesive tape or an adhesive binder. In paragraph 1,
A battery cell having a gas permeability of the lead film of 20 to 60 barrer at 60°C. In paragraph 1,
A battery cell having a moisture permeation amount of the lead film of 0.02 g to 0.2 g at 25°C and 50%RH for 10 years. In paragraph 1,
A battery cell having a gas permeability of the gas discharge induction section of 40 barrer or more at 60°C. A battery module comprising a battery cell according to claim 1.

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