Secondary battery and secondary battery module including same

Abstract

A secondary battery according to the present disclosure comprises: an electrode assembly; and a battery case in which the electrode assembly is accommodated and an edge of which is sealed, in which the battery case includes: at least one folded portion folded such that a tail end of a portion of the edge of the battery case is hidden inward; and at least one exposed portion through which a distal end of the other portion of the edge of the battery case is exposed to the outside.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2022-0085280 filed on Jul. 11, 2022 and Korean Patent Application No. 10-2023-0087159 filed on Jul. 5, 2023, which are hereby incorporated by reference in their entirety. Technical Field

[0004] The present disclosure relates to a secondary battery and a battery module including the same, and more particularly, to a secondary battery including an electrode assembly and a battery case accommodating the electrode assembly, and a battery module including the secondary battery. Background Art

[0005] Recently, secondary batteries have received considerable attention as energy sources for electric vehicles (EVs), hybrid electric vehicles (HEVs), and the like, which have been developed to address, for example, air pollution caused by existing gasoline and diesel vehicles using fossil fuels.

[0006] Although one or two to three or four secondary batteries are used on small mobile devices, since medium and large devices such as electric vehicles require high power and large capacity, a battery module in which multiple secondary batteries are electrically connected to each other or a battery pack in which multiple battery modules are electrically connected to each other is used.

[0007] Among the secondary batteries currently commercialized, one of the most popular secondary batteries may be the lithium secondary battery, which can be classified into can type, square type and soft pack type according to the shape of its external material. Among them, the soft pack type secondary battery is widely used in medium and large battery modules due to its high energy density and easy stacking.

[0008] In recent years, as the demand for secondary battery modules installed in vehicles has increased, consumers' requirements for stability have also increased. However, consumers require that the energy density of secondary batteries be increased within the limited space of secondary battery modules. In this case, there is a limitation that the risk of safety related to fire and explosion of secondary batteries also increases.

[0009] A soft-pack type secondary battery may have a structure in which an electrode assembly is contained in a soft-pack type battery case and the edges of the battery case are sealed. However, when a secondary battery catches fire, the temperature of the secondary battery increases, and the electrolyte evaporates inside the battery case to generate gas, which may be ejected through a weakly sealed portion of the battery case without a specific path.

[0010] Here, when the gas is ejected from a position adjacent to the electrode lead, a fatal problem may occur in which a spark causes the secondary battery to catch fire rapidly. Therefore, it is necessary to develop a technology to solve the above problem. Summary of the invention

[0011] Technical issues

[0012] The present disclosure has been invented to solve the above-mentioned problems, and an object of the present disclosure is to provide a secondary battery capable of minimizing the risk of fire by guiding the gas within the battery housing so that the gas is discharged to a designated location in the event of an emergency such as a fire of the secondary battery, and a secondary battery module including the secondary battery.

[0013] Technical Solution

[0014] A secondary battery according to the present disclosure may include: an electrode assembly; and a battery case, in which the electrode assembly is accommodated and the edge of the battery case is sealed, wherein the battery case includes: at least one folding portion, which is folded so that the end of a part of the edge of the battery case is hidden inwardly; and at least one exposed portion, through which the end of another part of the edge of the battery case is exposed to the outside.

[0015] When the internal pressure of the battery case is equal to or greater than a predetermined pressure, the sealing of the exposed portion may be released to discharge the gas inside the battery case.

[0016] The folded portion may be folded at least twice in one direction.

[0017] The exposed portion may be folded at least once so that a distal end of the edge is exposed to the outside.

[0018] The exposed portion may be folded in an opposite direction to the folded portion.

[0019] The exposed portion may be folded less times than the folded portion.

[0020] An interval between inner surfaces of the exposed portion facing each other may be greater than an interval between inner surfaces of the folded portion facing each other.

[0021] The secondary battery may further include an electrode lead protruding from one edge of the battery case, and the exposed portion may be provided on the other edge of the battery case.

[0022] The folded portion may be provided on another edge of the battery housing.

[0023] The exposed portion may be disposed adjacent to the folded portion.

[0024] The exposed portion may be provided in plural, the plurality of exposed portions may be spaced apart from each other in the longitudinal direction of the battery case, and the exposed portion may be provided between the plurality of folded portions.

[0025] The secondary battery may further include: a film portion folded such that both end portions of the film portion are connected to the exposed portion and surround a terminal end of the exposed portion.

[0026] When the pressure inside the battery case increases to a predetermined pressure or more and the sealing of the exposed portion is released, the membrane portion may be expanded in a state where both end portions of the membrane portion are connected to the outer surface of the exposed portion.

[0027] The membrane portion may be made of a porous material.

[0028] A secondary battery module according to an embodiment of the present disclosure may include: a plurality of secondary batteries arranged in one direction; and a housing configured to accommodate the plurality of secondary batteries. Each secondary battery may include: an electrode assembly; and a battery housing, the electrode assembly is accommodated in the battery housing, and the edge of the battery housing is sealed, wherein the battery housing may include: at least one folding portion, the at least one folding portion is folded so that the end of a portion of the edge of the battery housing is hidden inwardly; and at least one exposed portion, the end of another portion of the edge of the battery housing is exposed to the outside through the at least one exposed portion.

[0029] Beneficial Effects

[0030] The present disclosure may have the effect of minimizing the risk of fire caused by gas generated inside a battery case, thereby discharging the gas to a designated location by providing an exposure portion whose end is exposed to the outside at an edge of the battery case.

[0031] In addition, by further including a film portion connected to the exposed portion, the present disclosure may have the effect of preventing external moisture and foreign matter from being introduced into the battery case while discharging gas within the battery case.

[0032] In addition, the present disclosure can have the following effects: in a secondary battery module including multiple secondary batteries, an exposed portion whose ends are exposed to the outside is set at the edge of the battery case of the secondary battery, so that gas is discharged to a designated position to minimize the risk of fire, thereby suppressing and delaying the propagation of thermal runaway between the secondary batteries inside the secondary module. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a front view of a configuration of a secondary battery before the edge of a battery case is folded to manufacture the secondary battery according to Embodiment 1 of the present disclosure.

[0034] Figure 2 4 is a front view of a secondary battery according to Example 1 of the present disclosure.

[0035] Figure 3 yes Figure 2 Detail perspective view of the exposed portion of a secondary battery.

[0036] Figure 4 It is along Figure 2 A cross-sectional view taken along line AA.

[0037] Figure 5 It is along Figure 2 BB is a cross-sectional view taken on the line BB to show the state before the gas is discharged through the exposed portion.

[0038] Figure 6 It shows that the gas passes through Figure 5 A cross-sectional view of a state where the exposed portion is discharged.

[0039] Figure 7 It shows that the gas passes through Figure 2 A perspective view of a state in which an exposed portion of a secondary battery is discharged.

[0040] Figure 8 4 is a front view of a secondary battery according to Example 2 of the present disclosure.

[0041] Fig. 9 is a perspective view showing a state in which a film portion according to Embodiment 3 of the present disclosure is connected to an exposed portion in a secondary battery.

[0042] Fig.10 It shows that the gas passes through Fig. 9 A cross-sectional view of a state before the exposed portion of a secondary battery is discharged.

[0043] Fig.11 It shows that the gas passes through Fig.10 A cross-sectional view of a state where the exposed portion is discharged. DETAILED DESCRIPTION

[0044] Hereinafter, the preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present disclosure. However, the present disclosure can be implemented in several different forms and is not limited or constrained by the following examples.

[0045] In order to clearly describe the present disclosure, detailed descriptions of parts that are not related to the description or related known technologies that may unnecessarily obscure the main points of the present disclosure have been omitted, and in this specification, reference numerals are added to the components in the various drawings. In this case, the same or similar reference numerals represent the same or similar elements throughout the specification.

[0046] Furthermore, the terms or words used in the specification and claims should not be restrictively interpreted as ordinary meanings or dictionary-based meanings, but should be interpreted as meanings and concepts consistent with the scope of the present disclosure based on the principle that the inventor can appropriately define the concepts of the terms to best describe and interpret his or her invention.

[0047] Secondary battery

[0048] The secondary battery 100 according to an embodiment of the present disclosure may include an electrode assembly 110 and a battery case 120 that accommodates the electrode assembly 110 and whose edges are sealed. The battery case 120 may include at least one folded portion 121 folded so that the end of a portion of the edge of the battery case 120 is hidden inwardly and at least one exposed portion 122 through which the end of another portion of the edge of the battery case 120 is exposed outwardly.

[0049] The exposure portion 122 may be configured such that the seal is released when the internal pressure of the battery case 120 is higher than a predetermined pressure, thereby discharging the gas inside the battery case 120 .

[0050] In the present disclosure, the electrode assembly 110 may have various structures. For example, the electrode assembly 110 may be provided by sequentially stacking electrodes and separators. More specifically, the electrode assembly 110 may have a structure in which a positive electrode current collector / positive electrode active material layer / separator / negative electrode active material layer / negative electrode current collector are sequentially stacked, so that the positive electrode active material layer disposed on one surface of the separator faces the negative electrode active material layer disposed on the other surface of the separator. However, the type of the electrode assembly 110 is not limited thereto, and may also be configured as a wound type electrode assembly.

[0051] Note that the electrode assembly 110 is housed inside the battery case 120 and is indicated by a dotted line in the drawing.

[0052] In addition, the battery case 120 accommodating the electrode assembly 110 may be configured such that an edge thereof is sealed and may have various structures.

[0053] For example, the battery case 120 may be provided as two sheets on the upper and lower sides of the electrode assembly 110. In addition, in at least one of the two sheets, a portion of the sheet may be concavely formed to form an empty space to accommodate the electrode assembly 110. The electrolyte as well as the electrode assembly 110 may be accommodated in the empty space.

[0054] The battery case 120 may have an edge-sealed structure. This is done to prevent the electrode assembly 110 contained in the battery case 120 from being damaged due to exposure to external moisture and air. In this case, a method such as heat welding may be used to seal the edge of the battery case 120. The edge of the battery case 120 may be referred to as a platform portion or a sealing portion.

[0055] The secondary battery 100 according to the present disclosure may be configured such that the edge of the battery case 120 is folded to reduce the volume of the secondary battery 100 or to improve the sealing force of the battery case 120 , thereby improving energy density.

[0056] That is to say, Figure 1 As shown, in the secondary battery 100, the edge of the battery case 120 can be folded in the direction of the arrow in the unfolded state. Figure 2 As shown, the edge of the battery housing 120 may be arranged in a folded state.

[0057] Here, at least one of the exposure portion 122 and the folded portion 121 may be provided at the edge of the battery case 120 to discharge the gas to a designated location when the gas is generated in the battery case 120 due to the ignition of the secondary battery 100 .

[0058] Specifically, Figures 2 to 3 As shown, the battery case 120 may include at least one folded portion 121 folded so that an end of a portion of the edge of the battery case 120 is hidden inwardly and at least one exposed portion 122 through which an end of another portion of the edge of the battery case 120 is exposed outwardly.

[0059] Therefore, when a predetermined amount of gas is generated inside the battery case 120, the gas can be discharged preferentially from the exposed portion 122, which is relatively easier to discharge gas than the folded portion 121. Therefore, in the battery case 120 having the above structure, the user can discharge the gas to a designated position by selectively providing the exposed portion 122 on the battery case 120 to minimize the risk caused by the ignition of the secondary battery 100.

[0060] Hereinafter, the structures of the folded portion 121 and the exposed portion 122 will be described in more detail.

[0061] First, the folding portion 121 may be configured to be folded such that the end of the edge of the battery case 120 is hidden inwardly, and may have various structures.

[0062] Specifically, Figure 3 and Figure 4As shown, the folding portion 121 may be provided by folding a portion of the edge of the battery case 120. That is, the end of the edge portion of the battery case 120 may be the end 121a of the folding portion 121. The end 121a of the folding portion 121 may be hidden by the inner surfaces of the folding portion 121 facing each other.

[0063] Since the end 121 a through which the gas is discharged to the outside is hidden inwardly, the folded portion 121 can have a structure that is relatively more difficult for gas to be discharged than the exposed portion 122 whose end 122 a is exposed to the outside, and can therefore be understood as a configuration that guides gas to be discharged to the exposed portion 122 .

[0064] In addition, the folded portion 121 may have a structure in which external moisture or air is relatively difficult to be introduced due to the end 121 a being hidden inwardly, and may be understood as a configuration that improves the sealing force of the battery case 120 .

[0065] The folded portion 121 may have any structure as long as the end 121 a is hidden inwardly. For example, the folded portion 121 may have a configuration of being folded at least twice in one direction so that the end 121 a is wrapped inwardly at the edge of the battery case 120 .

[0066] In addition, even if gas is introduced into the folded portion 121 , inner surfaces of the folded portion 121 facing each other may be in contact with each other or adjacent to each other to prevent movement of the gas as much as possible.

[0067] The present disclosure may include the exposure portion 122 , and when the internal pressure of the battery case 120 is higher than a predetermined pressure, the sealing of the exposure portion 122 is released and the gas inside the battery case 120 is discharged.

[0068] Specifically, Figure 3 and Figure 5 As shown, the exposure portion 122 may be provided by folding a portion of the edge of the battery case 120. That is, the end of the edge portion of the battery case 120 may be the end 122a of the exposure portion 122. The end 122a of the exposure portion 122 may be exposed to the outside.

[0069] Therefore, since the end 122a through which the gas is discharged to the outside is exposed to the outside, the exposed portion 122 may have a structure that is relatively easy to discharge gas compared to the folded portion 121 whose end is hidden inward. The exposed portion 122 may be understood as a configuration that operates in preference to the folded portion 121 when gas is generated in the battery case 120 to serve as a gas discharge channel.

[0070] As long as the end 122a is exposed to the outside, the exposed portion 122 may have any structure. For example, the exposed portion 122 may have a structure that is folded at least once so that the end 122a is exposed to the outside. Here, the exposed portion 122 may be folded in the opposite direction to the folded portion 121. In addition, the exposed portion 122 may be folded less times than the folded portion 121.

[0071] In addition, an interval g2 between inner surfaces facing each other in the exposed portion 122 may be greater than an interval g1 between inner surfaces facing each other in the folded portion 121. Each of the intervals g1 and g2 may represent an average interval.

[0072] Therefore, when the internal pressure of the battery case 120 increases, gas may be discharged more smoothly and preferentially through the exposed portion 122 .

[0073] like Figure 5 As shown, when no gas is generated inside the battery case 120 or when the gas pressure inside the battery case 120 is less than a predetermined pressure, the exposed portion 122 may maintain a sealed state.

[0074] In addition, if Figure 6 As shown, even when gas is generated inside the battery case 120 and the internal pressure of the battery case 120 reaches a predetermined pressure or more, the sealing of the exposed portion 122 can be released to guide the discharge of the gas, thereby reducing the internal pressure of the battery case 120.

[0075] The exposure portion 122 may be provided in the battery case 120 in various ways.

[0076] However, the secondary battery 100 according to the present disclosure may further include an electrode lead 130 protruding from at least one end portion of the battery case 120. In this case, preferably, the exposure portion 122 is disposed at a position away from the electrode lead 130.

[0077] Since the electrode lead 130 is electrically connected to the electrode assembly 110 inside the battery case 120 and the external electrical device or the secondary battery 100 , this is because when the gas exhausted from the exposed portion 122 is exhausted at a position adjacent to the electrode lead 130 , sparks occur to cause rapid ignition.

[0078] like Figure 6 and Figure 7 As shown, when the electrode lead 130 protrudes from one edge of the battery case 120, the exposed portion 122 may be preferably provided at the other edge of the battery case 120. The folded portion 121 may also be provided at the other edge of the battery case 120.

[0079] More specifically, the electrode lead 130 may be disposed at a short side of the battery case 120 , and the folded portion 121 and the exposed portion 122 may be disposed at a long side of the battery case 120 .

[0080] The exposed portion 122 may be disposed adjacent to the folded portion 121. Preferably, the exposed portion 122 may be disposed between a plurality of folded portions 121.

[0081] The exposure portions 122 may be provided in different numbers and positions in the battery case 120 in consideration of the amount of gas generated inside the battery case 120 .

[0082] As an example, the exposed portion 122 may be provided as a portion and provided at a middle portion of an edge of the battery case 120. Figure 7 As another example, the exposed portion 122 may be as shown. Figure 8 As shown, a plurality of batteries are provided, and the battery housing 120 may be provided in the longitudinal direction (based on Figure 8 In this case, the plurality of exposed portions 122 may be alternately disposed with the plurality of folded portions 121.

[0083] The secondary battery 100 according to the present disclosure may further include a film portion 140 folded and surrounding the end 122 a of the exposed portion 122 .

[0084] Specifically, Figures 9 to 11 As shown, the film portion 140 may be configured such that both ends of the film portion 140 are connected to the exposed portion 122 and folded around a terminal end 122 a of the exposed portion 122 , and may have various structures.

[0085] More specifically, if Fig.10 As shown, when the exposed portion 122 is in a sealed state and when the internal pressure of the battery case 120 is less than a predetermined pressure, the film portion 140 may have a folded structure and surround the end of the exposed portion 122 .

[0086] Here, when the exposed portion 122 is in a sealed state so that even when the seal of the exposed portion 122 is released, the two end portions of the membrane portion 140 remain connected to the exposed portion 122, the membrane portion 140 can be configured so that the folded portion of the membrane portion 140 is spaced a predetermined distance from the end 122a of the exposed portion 122.

[0087] like Fig.11 As shown, when the internal pressure of the battery case 120 is higher than a predetermined pressure and the sealing of the exposed portion 122 is released, both ends of the film portion 140 may be unfolded in a state of being connected to the outer surface of the exposed portion 122 .

[0088] The membrane portion 140 may be made of a porous material. Therefore, when the seal of the exposed portion 122 is released, the gas inside the battery case 120 may be discharged to the outside, and at the same time, external moisture or foreign matter may be prevented from being introduced into the battery case 120.

[0089] In addition, the membrane portion 140 may be connected to the exposed portion 122 in various ways. Fig.10 and Fig.11 As shown, the film portion 140 may be connected to the exposed portion 122 by inserting an adhesive material 140a between the inner surface of the film portion 140 and the outer surface of the exposed portion 122. The adhesive material 140a may combine the film portion 140 and the exposed portion 122 by thermal fusion or the like.

[0090] Secondary battery module

[0091] A secondary battery module according to an embodiment of the present disclosure may include: a plurality of secondary batteries 100 arranged in one direction; and a housing accommodating the plurality of secondary batteries 100. Each secondary battery 100 may include: an electrode assembly 110; and a battery housing 120 accommodating the electrode assembly 110 and having its edges sealed. The battery housing 120 may include at least one folding portion 121 folded so that the end of a portion of the edge of the battery housing 120 is hidden inwardly and at least one exposed portion 122 through which the end of another portion of the edge of the battery housing 120 is exposed outwardly.

[0092] The exposure portion 122 may be configured so as to be released from sealing when the internal pressure of the battery case 120 is higher than a predetermined pressure, thereby discharging gas inside the battery case 120 .

[0093] Here, the plurality of secondary batteries 100 may be configured to be aligned in one direction in the accommodation space inside the case, and may have various configurations.

[0094] A more detailed description of the folded portion 121 and the exposed portion 122 may be replaced with the above contents.

[0095] The case may be configured to accommodate a plurality of secondary batteries 100 , and may have various configurations.

[0096] For example, the case may have an accommodation space defined therein to accommodate the secondary battery 100. In addition, a bus bar electrically connected to the electrode lead 130 of the secondary battery 100 and a heat sink discharging heat generated from the secondary battery 100 may be installed in the case.

[0097] While embodiments of the present disclosure have been described with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present disclosure as defined in the following claims.

[0098] [Explanation of Reference Numerals]

[0099] 100: Secondary battery 110: Electrode assembly

[0100] 120: battery case 121: folding part

[0101] 121a: end of the folded portion 122: exposed portion

[0102] 122a: end of the exposed portion 130: electrode lead

[0103] 140: membrane part 140a: adhesive material

Claims

1. A secondary battery comprising: Electrode assembly; as well as a battery case in which the electrode assembly is housed and whose edges are sealed, Wherein, the battery housing comprises: at least one folded portion, the at least one folded portion being folded so that an end of a portion of the edge of the battery case is hidden inwardly; and At least one exposed portion through which a distal end of the other portion of the edge of the battery case is exposed to the outside.

2. The secondary battery according to claim 1, wherein When the internal pressure of the battery case is equal to or greater than a predetermined pressure, the sealing of the exposure portion is released to discharge gas inside the battery case.

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

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

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

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

7. The secondary battery according to claim 4, wherein An interval between inner surfaces of the exposed portion facing each other is greater than an interval between inner surfaces of the folded portion facing each other.

8. The secondary battery according to claim 1, further comprising: an electrode lead protruding from one edge of the battery case, Wherein, the exposed portion is arranged on another edge of the battery housing.

9. The secondary battery according to claim 8, wherein The folded portion is provided on the other edge of the battery case.

10. The secondary battery according to claim 1, wherein The exposed portion is disposed adjacent to the folded portion.

11. The secondary battery according to claim 1, wherein The exposed portion is provided in plurality, and the plurality of exposed portions are spaced apart from each other in the longitudinal direction of the battery case, and The exposed portion is disposed between the plurality of folded portions.

12. The secondary battery according to claim 1, further comprising: A film portion is folded such that both ends of the film portion are connected to the exposed portion and surround a terminal end of the exposed portion.

13. The secondary battery according to claim 12, wherein: When the pressure inside the battery case increases to a predetermined pressure or more and the seal of the exposed portion is released, the film portion is expanded in a state where both end portions of the film portion are connected to the outer surface of the exposed portion.

14. The secondary battery according to claim 12, wherein The membrane portion is made of a porous material.

15. A secondary battery module, comprising: a plurality of secondary batteries, the plurality of secondary batteries being arranged in one direction; as well as a housing configured to accommodate the plurality of secondary batteries, Wherein, each of the secondary batteries comprises: an electrode assembly; and a battery case in which the electrode assembly is housed and whose edges are sealed, Wherein, the battery housing comprises: at least one folded portion, the at least one folded portion being folded so that a distal end of a portion of an edge of the battery case is hidden inwardly; and At least one exposed portion through which a distal end of another portion of the edge of the battery case is exposed to the outside.

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