Secondary battery and secondary battery module including the same

Abstract

The secondary battery according to the present invention includes an electrode assembly and a battery case in which the electrode assembly is housed and the edge portion is sealed. The battery case can include at least one folding portion that is folded so that a part of the end of the edge portion of the battery case is hidden inside, and at least one exposed portion where the other part of the end of the edge portion of the battery case is exposed outside.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0085280 filed on July 11, 2022, and Korean Patent Application No. 10-2023-0087159 filed on July 5, 2023, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference in their entirety.

[0002] The present invention relates to a secondary battery and a secondary battery module including the same, and more particularly, to a secondary battery including an electrode assembly and a battery case for accommodating the electrode assembly, and a secondary battery module including the same.

Background Art

[0003] Recently, secondary batteries have attracted attention as a power source for electric vehicles (EVs), hybrid electric vehicles (HEVs), etc., which are presented as a method for solving problems such as air pollution in existing gasoline vehicles and diesel vehicles using fossil fuels.

[0004] One or two to three secondary batteries are used for small mobile devices, while for medium and large-sized devices such as electric vehicles, due to the need for high power and large capacity, a battery module in which a number of secondary batteries are electrically connected or a battery pack in which a plurality of battery modules are electrically connected to each other is used.

[0005] Currently, one of the most spotlighted commercialized secondary batteries is the lithium secondary battery. The lithium secondary battery can be divided into a can type, a square type, a pouch type, etc. according to the shape of the exterior material. Among these, the pouch type secondary battery is widely used in medium and large-sized battery modules because of its advantages of high energy density and easy lamination.

[0006] On the one hand, in recent years, with the increasing demand for secondary battery modules installed in vehicles, customers' needs for stability have been gradually increasing. However, customers are demanding to increase the energy density of secondary batteries within the limited space of secondary battery modules. In this case, however, there arises a problem that the stability risks associated with the ignition and explosion of secondary batteries both increase.

[0007] The pouch-type secondary battery can have a structure in which an electrode assembly is housed in a pouch-type battery case and the edge of the battery case is sealed. However, when the secondary battery catches fire and the temperature of the secondary battery rises, and the electrolyte vaporizes inside the battery case to generate gas, the gas tends to jet out from a weak part of the seal of the battery case without a predetermined path.

[0008] At this time, when gas jets out from a position adjacent to the electrode lead, a fatal problem may occur in which the ignition of the secondary battery is rapidly caused by a spark. Therefore, there is a situation where it is necessary to develop a technology to solve the above problems.

Summary of the Invention

Problems to be Solved by the Invention

[0009] The present invention is derived to solve the above problems, and an object of the present invention is to provide a secondary battery and a secondary battery module including the same that can guide the gas inside the battery case to diverge at a specified position when an extraordinary situation such as the ignition of the secondary battery occurs, thereby minimizing the ignition risk.

Means for Solving the Problems

[0010] The secondary battery according to an embodiment of the present invention includes an electrode assembly and a battery case in which the electrode assembly is housed and the edge is sealed. The battery case can include at least one folding portion folded so that one end of a part of the edge of the battery case is hidden inside, and at least one exposed portion where the other end of a part of the edge of the battery case is exposed outside.

[0011] When the pressure inside the battery case is equal to or higher than a predetermined pressure, the exposed portion can be configured such that the seal is released and the gas inside the battery case is discharged.

[0012] The folding portion can be folded at least two or more times in one direction.

[0013] The exposed portion can be folded at least once so that the end of the edge portion is exposed to the outside.

[0014] The exposed portion can be folded in a direction opposite to that of the folding portion.

[0015] The exposed portion can be folded a smaller number of times than the folding portion.

[0016] The distance between the inner surfaces facing each other in the exposed portion may be larger than the distance between the inner surfaces facing each other in the folding portion.

[0017] The secondary battery can further include an electrode lead protruding from one edge portion of the battery case. The exposed portion can be formed on the other edge portion of the battery case.

[0018] The folding portion can be formed on the other edge portion of the battery case.

[0019] The exposed portion can be positioned adjacent to the folding portion.

[0020] A plurality of the exposed portions are formed at intervals along the longitudinal direction of the battery case, and the exposed portions can be provided between the plurality of folding portions.

[0021] The secondary battery may further include a membrane portion that is folded such that both ends are connected to the exposed portion and wrap the end of the exposed portion.

[0022] The membrane portion can be configured to be deployed with both ends connected to the outer surface of the exposed portion when the pressure inside the battery case increases to a predetermined pressure or more and the exposed portion is unsealed.

[0023] The membrane portion can have a porous material.

[0024] A secondary battery module according to an embodiment of the present invention can include a plurality of secondary batteries arranged in one direction and a housing that houses the plurality of secondary batteries. The secondary battery includes an electrode assembly and a battery case in which the electrode assembly is housed and the edge is sealed. The battery case includes at least one folding portion that is folded such that a part of the end of the edge of the battery case is hidden inside, and at least one exposed portion that exposes the end of another part of the edge of the battery case to the outside.

Advantages of the Invention

[0025] The present invention can minimize the risk of ignition by providing an exposed portion at the edge of the battery case where the end is exposed to the outside and guiding the gas generated inside the battery case to diverge at a specified position.

[0026] Further, the present invention can discharge the gas inside the battery case and prevent external moisture, foreign matter, etc. from penetrating into the battery case by further including a membrane portion connected to the exposed portion.

[0027] In addition, in a secondary battery module including a plurality of secondary batteries, the present invention provides an exposed portion with a terminal exposed to the outside at the edge of the battery case of the secondary battery, and guides the gas to diverge at a specified position, thereby minimizing the risk of ignition. As a result, there is an effect that the progress of thermal runaway propagation between secondary batteries inside the secondary battery module can be suppressed and delayed.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Modes for Carrying Out the Invention

[0029] Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail so that those having ordinary knowledge in the technical field to which the present invention pertains can easily implement it. However, the present invention can be realized in various different forms and is not limited or restricted by the following embodiments.

[0030] To clearly explain the present invention, detailed descriptions of parts not related to the explanation or related known technologies that may obscure the gist of the present invention are omitted. When attaching reference numerals to the components of each drawing in this specification, the same or similar reference numerals are attached to the same or similar components throughout the specification.

[0031] Also, the terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings. The inventors should interpret them in accordance with the meaning and concept that conform to the technical idea of the present invention in accordance with the principle that they can appropriately define the concept of the terms in order to explain their invention in the best way.

[0032] Secondary battery The secondary battery 100 according to an embodiment of the present invention can include an electrode assembly 110 and a battery case 120 in which the electrode assembly 110 is housed and the edge portion is sealed. The battery case 120 can include at least one folding portion 121 that is folded so that a part of the end of the edge portion of the battery case 120 is hidden inside, and at least one exposed portion 122 where the end of the other part of the edge portion of the battery case 120 is exposed outside.

[0033] The exposed portion 122 can be configured such that when the pressure inside the battery case 120 is equal to or higher than a predetermined pressure, the seal is released and the gas inside the battery case 120 is discharged.

[0034] In the present invention, the electrode assembly 110 can have various structures. For example, the electrode assembly 110 can be formed by laminating electrodes and separators in sequence. More specifically, the electrode assembly 110 can have a structure in which a positive current collector / a positive electrode active material layer / a separator / a negative electrode active material layer / a negative current collector are laminated in this order, with the positive electrode active material layer facing one side of the separator and the negative electrode active material layer facing the other side of the separator. However, the type of the electrode assembly 110 is not limited to this, and it goes without saying that it may be constituted by a jelly roll type electrode assembly.

[0035] Note that such an electrode assembly 110 is housed inside the battery case 120 and is represented by a dotted line in the drawing.

[0036] Also, the battery case 120 in which the electrode assembly 110 is housed has a structure with its edges sealed and can have various structures.

[0037] For example, the battery case 120 can be provided with two sheets on the upper and lower sides of the electrode assembly 110. Also, in at least one of the two sheets, a part of the region can be formed in a concave shape (forming) so that the electrode assembly 110 can be housed, thereby forming a free space. An electrolytic solution or the like can be housed in the free space together with the electrode assembly 110.

[0038] Such a battery case 120 can have a structure with its edges sealed, which may be for preventing the electrode assembly 110 housed inside the battery case 120 from being exposed to external moisture, air, etc. and being damaged. In this case, the edges of the battery case 120 can be sealed by a method such as heat sealing. The edges of the battery case 120 can be referred to as a terrace part or a sealing part.

[0039] On the one hand, for the secondary battery 100 according to the present invention, in order to improve the energy density or to further improve the sealing force of the battery case 120, the edge of the battery case 120 can be provided by being folded.

[0040] That is, as shown in FIG. 1, the edge of the battery case 120 of the secondary battery 100 described above can be folded in the direction of the arrow in the unfolded state, and thus, as shown in FIG. 2, the edge of the battery case 120 can be provided in the folded state.

[0041] Here, at least one exposed portion 122 and folding portion 121 can be formed at the edge of the battery case 120 so that when gas is generated inside the battery case 120 due to ignition of the secondary battery 100 or the like, the gas can be discharged at a designated position.

[0042] Specifically, as shown in FIGS. 2 to 3, the battery case 120 can include at least one folding portion 121 in which a part of the end of the edge of the battery case 120 is folded so as to be hidden inside, and at least one exposed portion 122 in which the other part of the end of the edge of the battery case 120 is exposed outside.

[0043] Thereby, when a certain amount or more of gas is generated inside the battery case 120, the gas can be discharged first from the exposed portion 122 where gas discharge is relatively easier than the folding portion 121. Therefore, in the battery case 120 having the above-described structure, the user can selectively arrange the exposed portion 122 on the battery case 120 to diverge the gas to a designated position, thereby minimizing the risk of ignition of the secondary battery 100.

[0044] Hereinafter, the structures of the folding portion 121 and the exposed portion 122 will be described in more detail.

[0045] First, the folding portion 121 is configured to be folded such that a part of the end of the edge of the battery case 120 is hidden inside, and it can have various structures.

[0046] Specifically, as shown in FIGS. 3 to 4, the folding portion 121 can be formed by folding a part of the edge of the battery case 120. That is, the end of a part of the edge of the battery case 120 can be the end 121a of the folding portion 121. The end 121a of the folding portion 121 can be hidden by the inner surfaces of the folding portion 121 that face each other.

[0047] Since the folding portion 121 has a structure in which the end 121a where gas can be released to the outside is hidden inside, it is a structure in which gas release is relatively difficult compared to the exposed portion 122 where the end 122a is exposed to the outside, and it can be understood as a configuration for guiding the release of gas to the exposed portion 122.

[0048] Also, since the end 121a of the folding portion 121 is hidden inside, it is a structure in which external moisture, air, etc. are relatively difficult to penetrate, and it can also be understood as a configuration for improving the sealing force of the battery case 120.

[0049] The above folding portion 121 can have any structure as long as the end 121a is hidden inside. For example, the folding portion 121 can have a structure in which it is folded at least two or more times in one direction so that the end 121a is wrapped inside at the edge of the battery case 120.

[0050] Also, even if gas flows into the folding portion 121, the inner surfaces of the folding portion 121 that face each other can be in contact or adjacent to each other so as to prevent the movement of gas to the maximum extent.

[0051] On the one hand, when the pressure inside the battery case 120 is equal to or higher than a predetermined pressure, the present invention can include an exposed portion 122 where the seal is released and the gas inside the battery case 120 is discharged.

[0052] Specifically, as shown in FIGS. 3 and 5, the exposed portion 122 can be formed by folding a part of the edge of the battery case 120. That is, the end of the other part of the edge of the battery case 120 can be the end 122a of the exposed portion 122. The end 122a of the exposed portion 122 can be exposed to the outside.

[0053] As a result, since the exposed portion 122 has the end 122a through which gas can be released to the outside exposed to the outside, it has a structure in which gas can be released more easily than the folding portion 121 whose end is hidden inside. The exposed portion 122 can be understood as a configuration that operates prior to the above-described folding portion 121 when gas is generated inside the battery case 120 and is used as a gas discharge passage.

[0054] The above-described exposed portion 122 can have any structure as long as the end 122a is exposed to the outside. For example, the exposed portion 122 can have a structure that is folded at least once so that the end 122a is exposed to the outside. Here, the exposed portion 122 can be folded in a direction opposite to that of the folding portion 121. Also, the exposed portion 122 can be folded fewer times than the folding portion 121.

[0055] In addition, the distance g2 between the inner surfaces facing each other in the exposed portion 122 can be larger than the distance g1 between the inner surfaces facing each other in the folding portion 121. Each of the distances g1 and g2 can mean the average distance.

[0056] As a result, when the pressure resistance of the battery case 120 increases, the discharge of gas through the exposed portion 122 can be induced to be smoother and occur earlier.

[0057] As shown in FIG. 5, such an exposed portion 122 can maintain a sealed state when no gas is generated inside the battery case 120 or when the pressure of the gas inside the battery case 120 is less than a predetermined pressure.

[0058] Also, as shown in FIG. 6, when gas is generated inside the battery case 120 and the pressure inside the battery case 120 reaches a predetermined pressure or more, the exposed portion 122 can have its seal released to induce gas release, thereby reducing the pressure inside the battery case 120.

[0059] On the other hand, the exposed portion 122 can be disposed at various positions in the battery case 120.

[0060] However, the secondary battery 100 according to the present invention can further include an electrode lead 130 protruding from at least one end of the battery case 120. In this case, the exposed portion 122 is preferably formed at a position maximally separated from the electrode lead 130.

[0061] This is because the electrode lead 130 is configured to be electrically connected to the electrode assembly 110 inside the battery case 120 and an external electrical device or the secondary battery 100, and when the gas discharged from the exposed portion 122 is discharged in the vicinity of the electrode lead 130, a problem may occur where a spark is generated and ignition occurs rapidly.

[0062] As shown in FIGS. 6 to 7, when the electrode lead 130 protrudes from one edge of the battery case 120, the exposed portion 122 is preferably formed at the other edge of the battery case 120. The folding portion 121 can also be formed at the other edge of the battery case 120.

[0063] More specifically, the electrode lead 130 can be located on the short side of the battery case 120, and the folding portion 121 and the exposed portion 122 can be located on the long side of the battery case 120.

[0064] The exposed portion 122 can be located adjacent to the folding portion 121. Preferably, the exposed portion 122 can be located between a plurality of folding portions 121.

[0065] On the other hand, the above-mentioned exposed portion 122 can be provided in various numbers and positions on the battery case 120 in consideration of the amount of gas generated inside the battery case 120.

[0066] As an example, one exposed portion 122 can be formed and can be provided at the central portion of the edge of the battery case 120 as shown in FIG. 7. As another example, as shown in FIG. 8, a plurality of exposed portions 122 can be formed and may be provided at intervals along the longitudinal direction (X direction in FIG. 8) of the battery case 120. In this case, the plurality of exposed portions 122 can be alternately positioned with the plurality of folding portions 121.

[0067] On the other hand, the secondary battery 100 according to the present invention may further include a membrane portion 140 that is folded so as to wrap the end 122a of the exposed portion 122.

[0068] Specifically, as shown in FIGS. 9 to 11, the membrane portion 140 has a configuration in which both ends are connected to the exposed portion 122 and are folded so as to wrap the end 122a of the exposed portion 122, and can have various structures.

[0069] More specifically, as shown in FIG. 10, when the pressure inside the battery case 120 is less than a predetermined pressure and the exposed portion 122 is in a sealed state, the membrane portion 140 can have a structure that is folded so as to wrap the end of the exposed portion 122.

[0070] Here, the membrane part 140 is folded by the membrane part 140 when the exposed part 122 is in a sealed state so that both ends of the membrane part 140 are maintained connected to the exposed part 122 even when the seal of the exposed part 122 is released, and the folded part can be provided at a predetermined interval from the end 122a of the exposed part 122.

[0071] On the other hand, as shown in FIG. 11, when the pressure inside the battery case 120 is equal to or higher than a predetermined pressure and the exposed part 122 is unsealed, the membrane part 140 can be deployed with both ends connected to the outer surface of the exposed part 122.

[0072] Such a membrane part 140 can be made of a porous material. Thereby, when the exposed part 122 is unsealed, the gas inside the battery case 120 can be released to the outside, and moisture and foreign substances from the outside can be prevented from penetrating into the battery case 120.

[0073] Also, the membrane part 140 can be connected to the exposed part 122 in various ways. For example, as shown in FIGS. 10 to 11, the membrane part 140 can be connected to the exposed part 122 by an adhesive substance 140a being interposed between the inner surface of the membrane part 140 and the outer surface of the exposed part 122. The adhesive substance 140a can join the membrane part 140 and the exposed part 122 by heat fusion or the like.

[0074] Secondary battery module The secondary battery module according to an embodiment of the present invention can include a plurality of secondary batteries 100 arranged in one direction and a housing that houses the plurality of secondary batteries 100. The secondary battery 100 can include an electrode assembly 110 and a battery case 120 in which the electrode assembly 110 is housed and the edge portion is sealed. The battery case 120 can include at least one folding portion 121 folded so that a part of the end of the edge portion of the battery case 120 is hidden inside, and at least one exposed portion 122 where the other part of the end of the edge portion of the battery case 120 is exposed outside.

[0075] The exposed portion 122 can be configured to release the seal and discharge the gas inside the battery case 120 when the pressure inside the battery case 120 is equal to or higher than a predetermined pressure.

[0076] Here, a plurality of secondary batteries 100 are arranged in one direction in the accommodation space inside the housing, and various configurations are possible.

[0077] A more detailed description of the folding portion 121 and the exposed portion 122 is as described above.

[0078] On the other hand, the housing is configured to house a plurality of secondary batteries 100, and various configurations are possible.

[0079] For example, the housing can have an accommodation space formed inside to house the secondary battery 100. In addition, a bus bar electrically connected to the electrode lead 130 of the secondary battery 100, a heat sink for discharging the heat generated by the secondary battery 100, etc. can be installed in the housing.

[0080] Although the present invention has been described with reference to limited embodiments and drawings, the present invention is not limited thereby, and various modifications can be made by those having ordinary knowledge in the technical field to which the present invention pertains within the equivalent scope of the technical idea of the present invention and the claims described below.

Explanation of Reference Numerals

[0081] 100 Secondary battery 110 Electrode assembly 120 Battery case 121 Folding part 121a End of folding part 122 Exposed part 122a End of exposed part 130 Electrode lead 140 Membrane part 140a Adhesive substance

Claims

1. An electrode assembly body, and a battery case in which the electrode assembly body is accommodated and the edge portion is sealed, wherein the battery case includes at least one folding portion that is folded so that a part of the end of the edge portion of the battery case is hidden inside, and at least one exposed portion where the end of the other part of the edge portion of the battery case is exposed outside, a secondary battery.

2. The exposed portion is configured such that when the pressure inside the battery case is equal to or higher than a predetermined pressure, the seal is released and the gas inside the battery case is discharged, the secondary battery according to claim 1.

3. The folding portion is folded at least twice in one direction, the secondary battery according to claim 1.

4. The exposed portion is folded at least once so that the end of the edge portion is exposed outside, the secondary battery according to claim 1.

5. The exposed portion is folded in a direction opposite to that of the folding portion, the secondary battery according to claim 4.

6. The exposed portion is folded fewer times than the folding portion, the secondary battery according to claim 4.

7. The distance between the inner surfaces facing each other in the exposed portion is larger than the distance between the inner surfaces facing each other in the folding portion, the secondary battery according to claim 4.

8. Further includes an electrode lead protruding from one edge portion of the battery case, wherein the exposed portion is formed on the other edge portion of the battery case, the secondary battery according to claim 1.

9. The folding portion is formed on the other edge portion of the battery case, the secondary battery according to claim 8.

10. The exposed portion is located adjacent to the folding portion, the secondary battery according to claim 1.

11. A plurality of the exposed portions are formed at intervals along the longitudinal direction of the battery case, and the exposed portions are provided between the plurality of folding portions, the secondary battery according to claim 1.

12. Further includes a membrane portion that is folded so that both ends are connected to the exposed portion and wrap the end of the exposed portion, the secondary battery according to claim 1.

13. The membrane portion The secondary battery according to claim 12, wherein when the pressure inside the battery case increases to a predetermined pressure or more and the exposed portion is unsealed, it is configured to be deployed with both ends connected to the outer surface of the exposed portion.

14. The secondary battery according to claim 12, wherein the membrane portion has a porous material.

15. A secondary battery module including a plurality of secondary batteries arranged in one direction, and a housing that houses the plurality of secondary batteries, wherein the secondary battery includes an electrode assembly, and a battery case that houses the electrode assembly and has its edge sealed, wherein the battery case includes at least one folding portion that is folded so that a part of the end of the edge of the battery case is hidden inside, and at least one exposed portion where the other part of the end of the edge of the battery case is exposed outside.

Images