Patent Description:
The present disclosure relates to a battery cell and a battery cell manufacturing apparatus, and more particularly, to a battery cell with improved external emission of gas generated inside the battery cell, and a battery cell manufacturing apparatus.

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 of great interest as energy sources not only for mobile devices such as mobile phones, digital cameras, notebooks and wearable devices, but also for power devices such as electric bicycles, electric vehicles and hybrid electric vehicles.

Depending on the shape of a battery case, these secondary batteries are classified into a cylindrical battery and a prismatic battery in which a battery assembly is included in a cylindrical or prismatic metal can, and a pouch-type battery in which the battery assembly is included in a pouch-type case of an aluminum laminate sheet. Here, the battery assembly included in the battery case is a power element including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and capable of charging and discharging, and is classified into a jelly-roll type in which long sheet-type positive and negative electrodes coated with an active material are wound with a separator being interposed therebetween, and a stack type in which a plurality of positive and negative electrodes are sequentially stacked with a separator being interposed therebetween.

Among them, in particular, a pouch-type battery in which a stack-type or stack/folding-type battery assembly is included in a pouch-type battery case made of an aluminum laminate sheet is being used more and more due to low manufacturing cost, small weight, and easy modification.

<FIG> is a top view showing a conventional battery cell. <FIG> is a cross-sectional view, taken along the axis a-a' of <FIG>. Referring to <FIG> and <FIG>, a conventional battery cell <NUM> includes a battery case <NUM> having an accommodation portion <NUM> in which a battery assembly <NUM> is mounted, and a sealing portion <NUM> formed by sealing an outer periphery thereof. Here, the battery cell <NUM> includes an electrode lead <NUM> protruding out of the battery case <NUM> via the sealing portion <NUM>, and a lead film <NUM> is located between upper and lower portions of the electrode lead <NUM> and the sealing portion <NUM>.

However, as the energy density of the battery cell increases in recent years, there is a problem that the amount of gas generated inside the battery cell also increases. In the case of the conventional battery cell <NUM>, a component capable of discharging the gas generated inside the battery cell is not included, so a venting may occur in the battery cell due to gas generation. In addition, moisture may penetrate into the battery cell damaged by the venting, which may cause side reactions, and there is a problem that battery performance deteriorates and additional gas is generated. Accordingly, there is an increasing need to develop a battery cell with improved external emission of gas generated inside the battery cell.

Document <CIT> discloses a battery cell having a gas discharge pipe for discharging the gas generated in the battery cell.

The present disclosure is directed to providing a battery cell with improved external emission of gas generated inside the battery cell, and a battery cell manufacturing apparatus.

The object to be solved by the present disclosure is not limited to the above-mentioned object, and the objects not mentioned here may be clearly understood by those skilled in the art from this specification and the accompanying drawings.

In one aspect of the present disclosure, there is provided a battery cell as defined in the appended claims.

In another aspect of the present disclosure, there is also provided a battery cell manufacturing apparatus for manufacturing the battery cell described above.

According to the embodiments, the present disclosure provides a battery cell, which includes an electrode lead to which a lead film having a dented portion dented inward and opened toward the outside of the battery case is formed, and an apparatus for manufacturing the battery cell, thereby improving the external emission of gas generated inside the battery cell.

In addition, according to the embodiments, in the present disclosure, the sealing portion located on the gas inlet portion of the dented portion includes a recessed sealing portion that is recessed from the inside to the outside of the battery case and does not overlap with at least a part of the gas inlet portion on a plane, thereby improving the external emission of gas generated inside the battery cell.

The effect of the present disclosure is not limited to the above effects, and the effects not mentioned here will be clearly understood by those skilled in the art from this specification and the accompanying drawings.

Hereinafter, with reference to the accompanying drawings, various embodiments of the present disclosure will be described in detail so as to be easily implemented by those skilled in the art. The present disclosure may be implemented in various different forms and is not limited to the embodiments described herein.

In order to clearly explain the present disclosure, parts irrelevant to the description are omitted, and identical or similar components are endowed with the same reference signs throughout the specification.

In addition, since the size and thickness of each component shown in the drawings are arbitrarily expressed for convenience of description, the present disclosure is not necessarily limited to the drawings. In order to clearly express various layers and regions in the drawings, the thicknesses are enlarged. Also, in the drawings, for convenience of explanation, the thickness of some layers and regions is exaggerated.

In addition, when a part of a layer, a film, a region, a plate, or the like is explained to be "over" or "on" another part, this includes not only the case where it is "directly on" another part, but also the case where still another part is provided therebetween. Conversely, when a part is explained to be "right on" another part, it means that there is no other part therebetween. In addition, when a part is explained to be "over" or "on" a reference part, this means that the part is located on or below the reference part, and it does not mean that the part is located "over" or "on" the reference part in a direction opposite to gravity.

In addition, throughout the specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

In addition, throughout the specification, when referring to "top view", it means that the target part is viewed from above, and when referring to "cross-sectional view", it means that a vertically-cut section of the target part is viewed from a side.

Hereinafter, a pouch battery cell <NUM> according to an embodiment of the present disclosure will be described. However, here, the description will be made based on one side surface of both side surfaces of the pouch battery cell <NUM>, but it is not necessarily limited thereto, and the same or similar contents may be described in the case of the other side surface.

<FIG> is a top view showing a battery cell according to this embodiment.

Referring to <FIG>, the battery cell <NUM> according to this embodiment includes a battery case <NUM>, an electrode lead <NUM>, and a lead film <NUM>.

The battery case <NUM> includes an accommodation portion <NUM> in which an electrode assembly <NUM> is mounted, and a sealing portion <NUM> formed by sealing an outer periphery thereof. The sealing portion <NUM> may be sealed by heat, laser, or the like. The battery case <NUM> may be a laminate sheet including a resin layer and a metal layer. More specifically, the battery case <NUM> may be made of a laminate sheet, and may include an outer resin layer forming the outermost layer, a barrier metal layer preventing penetration of materials, and an inner resin layer for sealing.

Also, the electrode assembly <NUM> may have a structure of a jelly-roll type (winding type), a stack type (lamination type), or a composite type (stack/folding type). More specifically, the electrode assembly <NUM> may include a positive electrode, a negative electrode, and a separator disposed therebetween.

Hereinafter, the electrode lead <NUM> and the lead film <NUM> will be mainly described.

<FIG> is a perspective view showing an electrode lead included in the battery cell of <FIG>.

Referring to <FIG> and <FIG>, the electrode lead <NUM> is electrically connected to an electrode tab <NUM> included in the electrode assembly <NUM>, and protrudes out of the battery case <NUM> via the sealing portion <NUM>. In addition, the lead film <NUM> is located at a portion corresponding to the sealing portion <NUM> in at least one of an upper portion and a lower portion of the electrode lead <NUM>. Accordingly, the lead film <NUM> may improve the sealing properties of the sealing portion <NUM> and the electrode lead <NUM> while preventing a short circuit from occurring in the electrode lead <NUM> during sealing.

<FIG> is a cross-sectional view, taken along the axis c-c' of <FIG>. <FIG> is a cross-sectional view, taken along the axis d-d' of <FIG>.

Referring to <FIG> and <FIG>, the lead film <NUM> has a dented portion <NUM> that is recessed in an inner direction of the battery case <NUM>, and the dented portion <NUM> is opened toward the outside of the battery case <NUM>. In addition, the inner surface of the dented portion <NUM> may be closed based on the protruding direction of the electrode lead <NUM>.

In addition, referring to <FIG> and <FIG>, the lead film <NUM> may further include an inner layer <NUM> covering at least one of the inner surfaces of the dented portion <NUM>.

For example, referring to <FIG> and <FIG>, the inner layer <NUM> in the dented portion <NUM> may cover the entire surface of the lead film <NUM>. That is, the inner layer <NUM> may be formed on the entire inner surface of the dented portion <NUM>, except for the opened surface.

Accordingly, even if the lead film <NUM> is sealed together with the sealing portion <NUM> in a state of being located in at least one of the upper and lower portions of the electrode lead <NUM>, the dented portion <NUM> may be preserved in a non-sealed state by the inner layer <NUM>.

As another example, referring to <FIG> and <FIG>, the inner layer <NUM> may cover an upper surface or a lower surface among the inner surfaces of the dented portion <NUM>. That is, the dented portion <NUM> may have an inner layer <NUM> formed on at least one of the upper and lower surfaces facing each other.

Accordingly, while the lead film <NUM> minimizes the inner layer <NUM> formed in the dented portion <NUM>, the dented portion <NUM> may be preserved in a non-sealed state by the inner layer <NUM>. In addition, the manufacturing process may be simplified and the cost may be reduced.

More specifically, the inner layer <NUM> may be made of a material having a higher melting point compared to the material constituting the lead film <NUM>. In addition, the inner layer <NUM> may be made of a material that does not react with the electrolytic solution contained in the battery case <NUM>. Accordingly, since the inner layer <NUM> is made of the above-described material, the inner layer <NUM> does not separately react with the electrolytic solution and does not cause heat fusion, thermal deformation, or the like in the high-temperature sealing process, so that the dented portion <NUM> may be kept blank. In addition, the gas generated in the battery case <NUM> may be easily discharged to the outside.

In one embodiment of the present disclosure, the thickness of the inner layer <NUM> may be <NUM> or less.

In one embodiment of the present disclosure, the gas permeability of the inner layer <NUM> may be <NUM> Barrer or more. For example, the carbon dioxide permeability of the inner layer <NUM> may satisfy the above range.

For example, the lead film <NUM> may include a polyolefin-based material, and the inner layer <NUM> may include at least one of polyolefin-based materials, fluorine-based materials, and porous ceramic-based materials. For example, the inner layer <NUM> may include at least one of polyolefin-based materials, fluorine-based materials, and porous ceramic-based materials that satisfies the above gas permeability value. The polyolefin-based material may include at least one material selected from the group consisting of polypropylene, polyethylene, and polyvinyl difluoride (PVDF). The fluorine-based material may include at least one material selected from the group consisting of polytetrafluoroethylene and polyvinylidene fluoride. In addition, the inner layer <NUM> may include a getter material, so that gas permeability may be increased while water permeability may be minimized. As an example, the getter material may be calcium oxide (CaO), barium oxide (BaO), lithium chloride (LiCl), silica (SiO<NUM>), or the like, and any material reacting with water (H<NUM>O) can be used without being limited thereto.

The inner layer <NUM> may have an adhesive material between the lead film <NUM> and the inner layer <NUM> or may be extruded together with the lead film <NUM> and adhered to the lead film <NUM>. The adhesive material may include an acryl-based material. In particular, when the inner layer <NUM> is extruded together with the lead film <NUM>, the gas permeability of the inner layer <NUM> may be <NUM> Barrer or more.

Referring to <FIG>, the lead film <NUM> may include a first lead film and a second lead film, the first lead film may be located at an upper portion of the electrode lead <NUM>, and the second lead film may be located at a lower portion of the electrode lead <NUM>. At this time, the electrode lead <NUM> may be sealed together with the sealing portion <NUM> in a state of being located between the first lead film and the second lead film, so that the first lead film and the second lead film may be connected to each other.

Accordingly, the lead film <NUM> may prevent the side surface of the electrode lead <NUM> from being exposed to the outside, while improving the sealing properties of the sealing portion <NUM> and the electrode lead <NUM>.

For example, in the lead film <NUM>, the dented portion <NUM> may be located in at least one of the first lead film and the second lead film. More specifically, in the lead film <NUM>, the dented portion <NUM> may be formed in the first lead film or the second lead film based on the electrode lead <NUM>, or the dented portion <NUM> may be formed in both the first lead film and the second lead film based on the electrode lead <NUM>. However, the number of the dented portion <NUM> is not limited to the above, and the lead film <NUM> may be formed in an appropriate number.

Accordingly, by adjusting the number of the dented portions <NUM> formed in the lead film <NUM>, the durability and airtightness of the lead film <NUM> may be controlled. In addition, by minimizing the number of the dented portion <NUM> as necessary, it is possible to simplify the manufacturing process and reduce the cost.

In one embodiment of the present disclosure, the gas permeability of the lead film <NUM> may be <NUM> Barrer to <NUM> Barrer, or <NUM> Barrer to <NUM> Barrer at <NUM>. For example, the carbon dioxide permeability of the lead film <NUM> may satisfy the above range. In addition, the gas permeability may satisfy the above range at <NUM> based on the thickness of the lead film <NUM> of <NUM>. If the gas permeability of the lead film <NUM> satisfies the above range, the gas generated inside the secondary battery may be more effectively discharged.

In this specification, the gas permeability may be measured by ASTM F2476-<NUM>.

In one embodiment of the present disclosure, the moisture penetration amount of the lead film <NUM> may be <NUM> to <NUM>, or <NUM> to <NUM>, or <NUM>, or <NUM> for <NUM> years at <NUM>, <NUM> %RH. If the moisture penetration amount of the lead film <NUM> satisfies the above range, the penetration of moisture from the lead film <NUM> may be more effectively prevented.

In this embodiment, the moisture penetration amount may be measured by adopting the ASTM F <NUM> method. At this time, the moisture penetration amount may be measured using equipment officially certified by MCOON.

In one embodiment of the present disclosure, the lead film <NUM> may have a gas permeability of <NUM> Barrer to <NUM> Barrer at <NUM> and a moisture penetration amount of <NUM> to <NUM> at <NUM>, <NUM> %RH for <NUM> years. If the gas permeability and the moisture penetration amount of the lead film <NUM> satisfy the above ranges, the penetration of moisture from the outside may be more effectively prevented while discharging the gas generated inside the secondary battery.

In one embodiment of the present disclosure, the lead film <NUM> may include a polyolefin-based resin. For example, the lead film <NUM> may include a polyolefin-based resin satisfying the gas permeability and/or moisture penetration amount values described above. The polyolefin-based resin may include at least one material selected from the group consisting of polypropylene, polyethylene, and polyvinyl difluoride (PVDF). While the lead film <NUM> contains polypropylene, the gas permeability of the lead film <NUM> may be <NUM> Barrer to <NUM> Barrer at <NUM>. Also, the moisture penetration amount may be <NUM> to <NUM>. In this case, the gas generated inside the secondary battery may be more effectively discharged, and the penetration of moisture from the outside may be easily prevented.

In addition, since the lead film <NUM> is made of the above-described material, the lead film <NUM> may maintain the airtightness of the battery cell <NUM> and prevent leakage of the internal electrolytic solution.

<FIG> is an enlarged view showing an electrode lead according to another embodiment of the present disclosure.

Referring to <FIG>, the battery cell <NUM> according to an embodiment of the present disclosure has a recessed sealing portion <NUM> formed inside the sealing portion <NUM>. Here, the recessed sealing portion <NUM> is recessed outward from the inside of the battery case <NUM>. More specifically, the recessed sealing portion <NUM> is recessed outward from the inside of the accommodation portion <NUM>.

In addition, the recessed sealing portion <NUM> is located on a gas inlet portion of the dented portion <NUM>.

Referring to <FIG>, the sealing portion <NUM> does not overlap with at least a part of the gas inlet portion on a plane. Here, when at least a part of the gas inlet portion and the sealing portion <NUM> do not overlap on a plane, it means that at least a part of the gas inlet portion and the sealing portion <NUM> do not overlap when the battery case <NUM> is viewed from the above. Since the recessed sealing portion <NUM> is located on the gas inlet portion of the dented portion <NUM>, it is possible to avoid interference between the gas inlet portion of the dented portion <NUM> and the sealing portion <NUM> in the lead film <NUM>, so that the gas inside the battery case <NUM> may easily flow into the dented portion <NUM>.

Referring to <FIG>, the dented portion <NUM> may include a first dented portion <NUM> and a second dented portion <NUM>. The first dented portion <NUM> may extend along the protruding direction of the electrode lead <NUM>, and the second dented portion <NUM> may extend along the length direction of the sealing portion <NUM>. Here, the length direction of the sealing portion <NUM> refers to a direction orthogonal to the protruding direction of the electrode lead <NUM>.

However, the shape of the dented portion <NUM> is not limited to the above, and the dented portion <NUM> may be formed in an appropriate shape within the lead film <NUM>.

Here, one end of the first dented portion <NUM> may be opened toward the outside of the battery case <NUM>, and the other end of the first dented portion <NUM> may communicate with the second dented portion <NUM>. More specifically, the first dented portion <NUM> and the second dented portion <NUM> may be integrated with each other. That is, the second dented portion <NUM> may serve as a gas inlet through which the gas generated in the battery case <NUM> is introduced, and the first dented portion <NUM> may serve as a gas outlet through which the gas introduced into the second dented portion <NUM> is discharged to the outside.

Also, referring to <FIG>, the recessed sealing portion <NUM> may be positioned on the second dented portion <NUM>. As another example, the recessed sealing portion <NUM> may also be positioned on a boundary line between the first dented portion <NUM> and the second dented portion <NUM>.

More specifically, the recessed sealing portion <NUM> may extend along the length direction of the second dented portion <NUM>. Here, the length of the second dented portion <NUM> means a maximum value of the distance between one end and the other end of the second dented portion <NUM> in a direction orthogonal to the protruding direction of the electrode lead <NUM>. In addition, the length of the recessed sealing portion <NUM> may be equal to or greater than the length of the second dented portion <NUM>. Here, the length of the recessed sealing portion <NUM> means a maximum value of the distance between one end and the other end of the recessed sealing portion <NUM> in a direction orthogonal to the protruding direction of the electrode lead <NUM>.

In addition, the width of the recessed sealing portion <NUM> may be equal to or greater than the width of the second dented portion <NUM>. Here, the width of the second dented portion <NUM> means a maximum value of the distance between one end and the other end of the second dented portion <NUM> in the protruding direction of the electrode lead <NUM>, and the width of the recessed sealing portion <NUM> means a maximum value of the distance between one end and the other end of the recessed sealing portion <NUM> in the protruding direction of the electrode lead <NUM>. However, the size of the recessed sealing portion <NUM> is not limited to the above, and the recessed sealing portion <NUM> may be formed in an appropriate size within the lead film <NUM>.

Accordingly, in the lead film <NUM>, the second dented portion <NUM> on the lead film <NUM> may not be in contact with the sealing portion <NUM>. In other words, a region of the lead film <NUM> where the second dented portion <NUM> is located may avoid interference with the sealing portion <NUM>. Accordingly, the second dented portion <NUM> may be exposed to the inside of the battery case <NUM>. Since the second dented portion <NUM> serves as a gas inlet through which the gas generated in the battery case <NUM> is introduced, the area in which the second dented portion <NUM> is exposed to the inside of the battery case <NUM> within the lead film <NUM> increases, so that gas may be smoothly introduced into the second dented portion <NUM> from the inside of the battery case <NUM>.

Referring to <FIG>, in the lead film <NUM>, the dented portion <NUM> may be formed at various positions with respect to the electrode lead <NUM>.

For example, as shown in <FIG>, in the lead film <NUM>, the dented portion <NUM> may be located over the electrode lead <NUM>. More specifically, the dented portion <NUM> may be formed at a position corresponding to the center of the electrode lead <NUM>.

As another example, as shown in <FIG>, the length of the lead film <NUM> may be greater than the width of the electrode lead <NUM>, and the dented portion <NUM> may be located between the end of the electrode lead <NUM> and the end of the lead film <NUM>. Here, the length of the lead film <NUM> means a maximum value of the distance between one end and the other end of the lead film <NUM> in a direction orthogonal to the protruding direction of the electrode lead <NUM>, and the width of the electrode lead <NUM> means a maximum value of the distance between one end and the other end of the electrode lead <NUM> in a direction orthogonal to the protruding direction of the electrode lead <NUM>. In other words, in the lead film <NUM>, the dented portion <NUM> may be formed at a position avoiding the electrode lead <NUM>. However, the position of the dented portion <NUM> is not limited to the above, and the dented portion <NUM> may be formed at an appropriate position within the lead film <NUM>.

Accordingly, by adjusting the position of the dented portion <NUM> formed in the lead film <NUM>, the durability and airtightness of the lead film <NUM> may be controlled. In addition, if necessary, by adjusting the size of the dented portion <NUM> according to the position of the dented portion <NUM>, it is possible to simplify the manufacturing process and reduce the cost.

In addition, referring to <FIG> and <FIG>, according to this embodiment, the lead film <NUM> and the electrode tab <NUM> may be spaced apart from each other based on the electrode lead <NUM>. Since the lead film <NUM> on the recessed end of the dented portion <NUM> does not come into contact with the sealing portion <NUM>, the lead film <NUM> may be designed to have a shorter width than the conventional one, so the lead film <NUM> and the electrode tab <NUM> may be sufficiently spaced apart from each other. Here, the width of the lead film <NUM> refers to a maximum value of the distance between one end and the other end of the lead film in the protruding direction of the electrode lead <NUM>.

Accordingly, it is possible to prevent a step from being created as the lead film <NUM> and the electrode tab <NUM> overlap with each other, and it is also possible to prevent poor adhesion performance from occurring due to the step and to prevent the battery cell <NUM> from being damaged at high pressure.

<FIG> is a cross-sectional view, taken along the axis b-b' of <FIG>.

Referring to <FIG>, the gas generated inside the battery cell <NUM> may be discharged toward the dented portion <NUM> of the lead film <NUM>. Here, the internal pressure of the battery cell <NUM> is higher than the internal pressure of the dented portion <NUM>, and the resulting pressure difference may act as a driving force of the gas. Here, since the dented portion <NUM> is opened toward the outside, the pressure inside the dented portion <NUM> may be the same as the pressure outside.

Accordingly, the gas generated inside the battery cell <NUM> may be discharged toward the dented portion <NUM>, and the gas introduced into the dented portion <NUM> may be easily discharged toward the outside. In addition, the external emission of gas generated inside the battery cell <NUM> may also be increased.

In addition, since the dented portion <NUM> is recessed in the inner direction of the battery case <NUM> and is opened toward the outside of the battery case <NUM>, the dented portion <NUM> may not be exposed to the electrolytic solution inside the battery case <NUM>, and airtightness and durability of the pouch may also be secured.

At this time, the recessed end of the dented portion <NUM> may serve as a gas inlet through which the gas generated in the battery case <NUM> is introduced, and the end of the dented portion <NUM> that is open toward the outside of the battery case <NUM> may serve as a gas outlet through which the gas introduced into the dented portion <NUM> is discharged to the outside.

Referring to <FIG>, the thickness H of the lead film <NUM> surrounding the upper surface of the dented portion <NUM> may be <NUM> to <NUM>, or <NUM> to <NUM>. In this specification, if the thickness H of the lead film <NUM> surrounding the upper surface of the dented portion <NUM> satisfies the above range, the gas inside the battery case <NUM> may be more easily introduced into the dented portion <NUM>. In this specification, the lead film <NUM> surrounding the upper surface of the dented portion <NUM> refers to the lead film <NUM> between the dented portion <NUM> and the electrode lead <NUM>.

Referring to <FIG>, based on the protruding direction of the electrode lead <NUM>, the width W of the lead film <NUM> surrounding the rear surface of the dented portion <NUM> may be <NUM> or more, or <NUM> to <NUM>. Here, the width of the lead film <NUM> surrounding the rear surface of the dented portion <NUM> means a maximum value of the distance between the recessed end of the dented portion <NUM> and the inner end of the battery case <NUM> of the lead film <NUM>. If the width W of the lead film <NUM> surrounding the rear surface of the dented portion <NUM> satisfies the above range, it may be more easy to prevent the lead film <NUM> from being torn while the gas generated inside the battery case <NUM> is introduced into the dented portion <NUM>.

If the sealing portion <NUM> comes into contact with the gas inlet portion when the gas generated in the battery case <NUM> flows into the dented portion <NUM>, the inflow of gas from the inside of the battery case <NUM> into the dented portion <NUM> may be disturbed by the sealing portion <NUM>. Accordingly, there is a problem in that the amount of gas flowing into the dented portion <NUM> is greatly reduced. For example, in the lead film <NUM>, the gas inside the battery case <NUM> may be introduced into the dented portion <NUM> due to gas permeation on the lead film at the upper surface of the recessed end of the dented portion <NUM>. Here, if the lead film on the upper surface of the recessed end of the dented portion <NUM> comes into contact with the sealing portion <NUM>, the inflow of gas from the inside of the battery case <NUM> into the dented portion <NUM> may be disturbed by the sealing portion <NUM>.

Referring to <FIG>, the recessed sealing portion <NUM> is positioned on the gas inlet portion of the dented portion <NUM>, and thus it is possible to avoid interference between the gas inlet portion of the dented portion <NUM> and the sealing portion <NUM> in the lead film <NUM>.

In addition, in the lead film <NUM>, the gas inlet portion of the dented portion <NUM> may be exposed to the inside of the battery case <NUM>. In this specification, the inside of the battery case <NUM> means a space in the inner direction of the battery case <NUM> rather than the end of the sealing portion <NUM> at the inner side of the battery case. That is, in the lead film <NUM>, since the area in which the gas inlet portion of the dented portion <NUM> is exposed to the inside of the battery case <NUM> is increased, gas may be smoothly introduced into the dented portion <NUM> from the inside of the battery case <NUM>.

<FIG> is a cross-sectional view, taken along the axis b-b' of <FIG>, in still another embodiment of the present disclosure.

Referring to <FIG>, an air ventilation layer <NUM> may be inserted in the dented portion <NUM>. The air ventilation layer <NUM> contains a material with higher air ventilation than the lead film <NUM>. Higher air ventilation may mean that, when a gas having a predetermined pressure is transmitted in one direction, the amount of the transmitted gas is relatively larger. If the air ventilation layer <NUM> is inserted in the dented portion <NUM>, the gas generated inside the battery case <NUM> and introduced into the dented portion <NUM> may be discharged to the outside of the battery case <NUM> by the air ventilation layer <NUM> having high ventilation even if the pressure does not exceed a predetermined level, and thus the gas inside the cell may be more easily discharged to the outside of the cell.

For example, the air ventilation layer <NUM> may include a material that is more porous than the lead film <NUM>. That is, the air ventilation layer <NUM> may include a material having a higher ratio of pores per unit volume than the lead film <NUM>.

In one embodiment of the present disclosure, the gas permeability of the air ventilation layer <NUM> may be <NUM> e<NUM> Barrer to <NUM> e<NUM> Barrer, or <NUM> e<NUM> Barrer to <NUM> e<NUM> Barrer. For example, the carbon dioxide permeability of the air ventilation layer <NUM> may satisfy the above range.

In one embodiment of the present disclosure, the air ventilation layer <NUM> may include at least one material selected from the group consisting of a polyolefin-based resin, a fluorine-based resin, a natural material, a glass fiber, a ceramic fiber, and a metal fiber. For example, the air ventilation layer <NUM> may include at least one material selected from the group consisting of a polyolefin-based resin, a fluorine-based resin, a natural material, glass fiber, a ceramic fiber, and a metal fiber that satisfy the gas permeability described. The polyolefin-based resin may include at least one material selected from the group consisting of polypropylene, polyethylene, and polyvinyl difluoride (PVDF). The fluorine-based resin may include at least one material selected from the group consisting of polytetrafluoroethylene and polyvinylidene fluoride, and the natural material may include at least one material selected from the group consisting of cotton and wool.

In one embodiment of the present disclosure, the thickness of the air ventilation layer <NUM> may be <NUM> to <NUM>, or <NUM> to <NUM>. If the thickness of the air ventilation layer <NUM> satisfies the above range, the gas inside the battery case <NUM> may be more easily discharged to the outside of the battery case <NUM>.

<FIG> is a cross-sectional view showing a battery cell manufacturing apparatus according to another embodiment of the present disclosure. <FIG> is a cross-sectional view showing a first sealing tool <NUM> according to an embodiment of the present disclosure, and <FIG> is a cross-sectional view showing a first sealing tool <NUM> according to another embodiment of the present disclosure.

Referring to <FIG>, the battery cell manufacturing apparatus according to this embodiment is an apparatus for manufacturing the battery cell <NUM>, and includes a first sealing tool <NUM> in which a first sealing surface <NUM> and a recessed surface <NUM> are formed.

The recessed surface <NUM> seals the battery case <NUM> on at least a part of the gas inlet portion of the dented portion <NUM>. Accordingly, the recessed sealing portion <NUM> may be formed.

The first sealing surface <NUM> seals the battery case <NUM> on the dented portion <NUM> except for the region sealed by the recessed surface <NUM>.

By using the first sealing tool <NUM>, it is possible to form the recessed sealing portion <NUM> by the recessed surface <NUM> while maintaining the sealing property or adhesion performance between the sealing portion <NUM> and the lead film <NUM>. The shape of the recessed surface <NUM> is not limited thereto, and the recessed surface <NUM> may have a structure recessed in a rectangular shape, a semi-circular shape, or the like having a size capable of maintaining the sealing property of the battery case <NUM>.

In one embodiment of the present disclosure, the length of the first sealing surface <NUM> may extend along the length direction of the dented portion <NUM>. However, the first sealing surface <NUM> does not extend to the gas inlet portion of the dented portion <NUM>. Here, the length of the first sealing surface <NUM> means a maximum value of the distance between one end and the other end of the first sealing surface <NUM> in the protruding direction of the electrode lead <NUM>, and the length of the dented portion <NUM> means a maximum value of the distance between one end and the other end of the dented portion <NUM> in the protruding direction of the electrode lead <NUM>.

In addition, the width of the first sealing surface <NUM> may extend along the width direction of the dented portion <NUM>. Here, the width of the first sealing surface <NUM> means a maximum value of the distance between one end and the other end of the first sealing surface <NUM> in a direction orthogonal to the protruding direction of the electrode lead <NUM>, and the width of the dented portion <NUM> means a maximum value of the distance between one end and the other end of the dented portion <NUM> in a direction orthogonal to the protruding direction of the electrode lead <NUM>. The width of the first sealing surface <NUM> may be equal to or greater than the width of the dented portion <NUM>.

Referring to <FIG>, the first sealing tool <NUM> may include a first sealing surface <NUM>, a recessed surface <NUM>, and a first inclined surface <NUM>.

Referring to <FIG>, the recessed surface <NUM> may be formed as an inclined surface, like the first inclined surface <NUM>, but the inclination angle of the recessed surface <NUM> may be smaller than the inclination angle of the first inclined surface <NUM>.

<FIG> is a cross-sectional view showing a battery cell manufacturing apparatus according to another embodiment of the present disclosure. <FIG> is a cross-sectional view showing a second sealing tool <NUM> according to an embodiment of the present disclosure, and <FIG> is a cross-sectional view showing a second sealing tool <NUM> according to another embodiment of the present disclosure.

Referring to <FIG>, the battery cell manufacturing apparatus according to the present embodiment may further include a second sealing tool <NUM> in which a second sealing surface <NUM> is formed.

The second sealing surface <NUM> seals the battery case <NUM> except for the region on the dented portion <NUM>. Accordingly, even if the dented portion <NUM> is located in the lead film <NUM>, a portion of the lead film <NUM> where the dented portion <NUM> is not located and the sealing portion <NUM> may be sealed with each other, so that the sealing force of the battery case <NUM> may be improved by the second sealing tool <NUM>.

In one embodiment of the present disclosure, the length of the first sealing surface <NUM> may be shorter than the length of the second sealing surface <NUM>. That is, the length of the sealing portion <NUM> formed by the first sealing surface <NUM> may be shorter than the length of the sealing portion <NUM> formed by the second sealing surface <NUM>. Accordingly, the sealing portion <NUM> is not positioned on the gas inlet portion of the dented portion <NUM>, so that gas may be smoothly introduced into the dented portion <NUM> from the inside of the battery case <NUM>.

Referring to <FIG>, the second sealing tool <NUM> may include a second sealing surface <NUM>, and a second inclined surface <NUM>.

In one embodiment of the present disclosure, the inclination angle of the first inclined surface <NUM> may be identical or similar to the inclination angle of the second inclined surface <NUM>. Accordingly, the inclination angles of the outer surfaces of the accommodation portion <NUM> respectively in contact with the first inclined surface <NUM> and the second inclined surface <NUM> may be identical or similar to each other.

In one embodiment of the present disclosure, the first sealing tool <NUM> and the second sealing tool <NUM> may be integrated with each other. For example, the first sealing tool <NUM> and the pair of second sealing tools <NUM> are integrated, and the first sealing tool <NUM> may be located between the pair of second sealing tools <NUM>. Here, depending on the position of the dented portion <NUM>, the pair of second sealing tools <NUM> may have the same width or different widths.

Accordingly, depending on the position of the dented portion <NUM>, the first sealing tool <NUM> and the second sealing tool <NUM> are integrated, thereby simplifying the manufacturing process of the battery cell <NUM> and reducing the cost.

<FIG> is a cross-sectional view, taken along the axis b1-b1' of <FIG>, showing the battery cell manufactured by the battery cell manufacturing apparatus of <FIG>.

Referring to <FIG> and <FIG>, the first sealing tool <NUM> may include a first upper sealing tool <NUM> and a first lower sealing tool <NUM>. In addition, the first upper sealing tool <NUM> includes a first upper inclined surface <NUM>, a first upper sealing surface <NUM> and an upper recessed surface <NUM> formed therein, and the first lower sealing tool <NUM> includes a first lower inclined surface <NUM>, a first lower sealing surface <NUM> and a lower recessed surface <NUM> formed therein. Here, the first upper sealing tool <NUM> is located at the upper part, and the first lower sealing tool <NUM> is located at the lower part, based on the sealing portion <NUM>. Here, the following description is based on the first upper sealing tool <NUM>, but the same description may also be applied to the first lower sealing tool <NUM>.

More specifically, in the first upper sealing tool <NUM>, the upper recessed surface <NUM> may be located on at least a part of the gas inlet portion of the dented portion <NUM>, and the first upper sealing surface <NUM> may be located on the battery case <NUM> on the dented portion <NUM> except for the region sealed by the upper recessed surface <NUM>. That is, the upper recessed surface <NUM> may be in contact with the outer surface of the accommodation portion <NUM> to form the recessed sealing portion <NUM> on the lead film in which the gas inlet portion of the dented portion <NUM> is positioned. In addition, the first upper sealing surface <NUM> may be in contact with the sealing portion <NUM> to seal the battery case <NUM>.

For example, when the dented portion <NUM> includes the first dented portion <NUM> and the second dented portion <NUM> as shown in <FIG>, the length of the first upper sealing surface <NUM> may extend along the length direction of the first dented portion <NUM>, and the length of the upper recessed surface <NUM> may extend along the width direction of the second dented portion <NUM>. Here, the length of the first upper sealing surface <NUM> means a maximum value of the distance between one end and the other end of the first upper sealing surface <NUM> based on the protruding direction of the electrode lead <NUM>, and the length of the first dented portion <NUM> means a maximum value of the distance between one end and the other end of the first dented portion <NUM> based on the protruding direction of the electrode lead <NUM>. In addition, the length of the upper recessed surface <NUM> means a maximum value of the distance between one end and the other end of the upper recessed surface <NUM> based on the protruding direction of the electrode lead <NUM>.

In addition, the widths of the first upper sealing surface <NUM> and the upper recessed surface <NUM> may extend along the length direction of the second dented portion <NUM>. Here, the width of the first upper sealing surface <NUM> means a maximum value of the distance between one end and the other end of the first upper sealing surface <NUM> in a direction orthogonal to the protruding direction of the electrode lead <NUM>, and the width of the upper recessed surface <NUM> means a maximum value of the distance between one end and the other end of the upper recessed surface <NUM> in a direction orthogonal to the protruding direction of the electrode lead <NUM>.

Accordingly, in the manufacturing apparatus according to the present embodiment, the recessed sealing portion <NUM> may be formed on the region where the gas inlet of the dented portion <NUM> is located, by the first sealing tool <NUM>. Accordingly, gas may be smoothly introduced into the dented portion <NUM> from the inside of the battery case <NUM>.

<FIG> is a cross-sectional view, taken along the axis b2-b2' of <FIG>, showing the battery cell manufactured by the battery cell manufacturing apparatus of <FIG>.

Referring to <FIG> and <FIG>, the second sealing tool <NUM> may include a second upper sealing tool <NUM> and a second lower sealing tool <NUM>. In addition, the second upper sealing tool <NUM> includes a second upper inclined surface <NUM> and a second upper sealing surface <NUM> formed therein, and the second lower sealing tool <NUM> includes a second lower inclined surface <NUM> and a second lower sealing surface <NUM> formed therein. The second upper sealing tool <NUM> is located at an upper side and the second lower sealing tool <NUM> is located at a lower side, based on the sealing portion <NUM>. Here, the following description will be based on the second upper sealing tool <NUM>, but the same description may also be applied to the second lower sealing tool <NUM>.

More specifically, in the second upper sealing tool <NUM>, the second upper sealing surface <NUM> may be located on the region of the sealing portion <NUM> where the dented portion <NUM> is not located. That is, in the second sealing tool <NUM>, the second sealing surface <NUM> may be located on the battery case <NUM> except for the region on the dented portion <NUM> based on the lead film <NUM>, so that the lead film <NUM> and the sealing portion <NUM> may be sealed.

Accordingly, even if the dented portion <NUM> is located in the lead film <NUM>, the region of the lead film <NUM> where the dented portion <NUM> is not located and the sealing portion <NUM> may be sealed with each other, so that the sealing force of the battery case <NUM> may be improved by the second sealing tool <NUM>.

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

Claim 1:
A battery cell (<NUM>), comprising:
a battery case (<NUM>) having an accommodation portion (<NUM>) in which an electrode assembly (<NUM>) is mounted, and a sealing portion (<NUM>) formed by sealing an outer periphery thereof;
an electrode lead (<NUM>) electrically connected to an electrode tab (<NUM>) included in the electrode assembly (<NUM>) and protruding out of the battery case (<NUM>) via the sealing portion (<NUM>); and
a lead film (<NUM>) located at a portion corresponding to the sealing portion (<NUM>) in at least one of an upper portion and a lower portion of the electrode lead (<NUM>),
wherein the lead film (<NUM>) has a dented portion (<NUM>) that is recessed in an inner direction of the battery case (<NUM>),
the dented portion (<NUM>) is opened toward the outside of the battery case (<NUM>),
the sealing portion (<NUM>) located on a gas inlet portion of the dented portion (<NUM>) has a recessed sealing portion (<NUM>) that is recessed outward from an inner side of the battery case (<NUM>), and
the recessed sealing portion (<NUM>) does not overlap with at least a part of the gas inlet portion on a plane.