Battery cell and battery module comprising same

Abstract

According to the present invention, it is possible to provide a battery cell and a battery module comprising the battery cell, in which a folded part is formed in a sealing part of a case for sealing the battery cell, deformation of the sealing part is suppressed by a structure in which an adhesive tape is adhered to only a part of the case and the folded part, and the cooling efficiency of the battery cell is not reduced.

Description

Technical Field

[0001] The present invention relates to a battery cell capable of suppressing deformation of a sealing portion and improving cooling efficiency, and a battery module including the battery cell. Background Art

[0002] With the development of the electronics, communications and aerospace industries, the demand for secondary batteries as energy sources has increased dramatically. In particular, with the emphasis on the importance of global environmental protection policies, the electric vehicle market is growing rapidly, and research and development of secondary batteries is being actively carried out both at home and abroad.

[0003] Among various secondary batteries, the research and development of lithium secondary batteries having high discharge voltage and energy density is most actively carried out. Such lithium secondary batteries are manufactured by accommodating an electrode assembly including a negative electrode, a positive electrode and a separator in a bag-type outer packaging material having high flexibility and then heat-welding the edges of the bag-type outer packaging material.

[0004] However, as the pressure inside the battery cell increases, the problem of rupture of the heat-welded seal occurs. In order to enhance the stability of the seal, a method of folding the seal or a method of taping the entire side of the bag-type outer packaging material on which the seal is formed has been introduced. However, even if the seal is folded, there is still the problem that the seal is easily ruptured due to the increase in the internal pressure of the battery cell. Moreover, in the case of taping the entire side of the bag-type outer packaging material, the problem of reduced cooling effect of the battery cell occurs due to the space formed between the bag-type outer packaging material and the tape.

[0005] Therefore, a method is needed to suppress the deformation of the sealing portion without reducing the cooling effect of the battery cell. Summary of the invention

[0006] Technical issues

[0007] The present invention provides a battery cell and a battery module including the battery cell, which suppress the deformation of the sealing part and improve the cooling efficiency of the battery cell by introducing a structure in which a folded part is formed in the sealing part of the battery cell and a tape is only attached to a part of the outer shell and the folded part.

[0008] Technical Solution

[0009] The battery cell according to the present invention includes: an electrode assembly; a shell body, including a first sheet material having a cup portion for accommodating the electrode assembly and a second sheet material covering the first sheet material; a sealing portion formed by joining the inner surface of the first sheet material and the edge of the inner surface of the second sheet material; a folding portion formed by folding the sealing portion; and an attachment component bonded to one side of the folding portion and the outer surface of the second sheet material.

[0010] According to an embodiment, the sealing portion includes: a first sealing portion joined in a state where an electrode tab extending from the electrode assembly is clamped; and a second sealing portion joined in a state where the electrode tab is not clamped, and the folding portion may be formed in the second sealing portion.

[0011] According to an embodiment, the second sealing portion may further include a joining portion that does not form the folded portion.

[0012] According to an embodiment, the attaching member may not be bonded to the joint portion.

[0013] According to an embodiment, the folding portion may be closely attached to the housing body through the attaching component.

[0014] According to an embodiment, the folded portion may be formed by folding the sealing portion toward the center direction of the housing body one or more times.

[0015] According to an embodiment, the folding portion includes: a first folding surface opposite to the outer surface of the second sheet; and a second folding surface located at the outermost contour of the folding portion with respect to the shell body, and the attachment component can be bonded to the second folding surface.

[0016] According to an embodiment, the attaching member may include an insulating resin.

[0017] According to an embodiment, the thickness of the attaching member may be 0.1 mm to 2.00 mm.

[0018] According to an embodiment, a plurality of the attaching members may be arranged at intervals along the length direction of the second sealing portion.

[0019] The battery module according to the invention comprises the battery cell according to the invention as a unit cell.

[0020] According to an embodiment, the battery module may include a heat dissipation plate.

[0021] According to an embodiment, the battery module may include a gap filler disposed between the battery cell and the heat dissipation plate.

[0022] According to an embodiment, the gap filler may be in contact with an attachment part of the battery cell and an outer surface of the first sheet of the battery cell.

[0023] Effects of the Invention

[0024] According to the battery cell of the present invention, the folded portion is formed in the seal portion, and thus there is an effect of stably fixing the seal portion of the battery cell to suppress deformation of the seal portion.

[0025] Furthermore, in the battery cell according to the present invention, the sealing portion can be more stably fixed due to the attachment member formed on the folded portion, thereby delaying venting that causes the outer case to be opened and maintaining the performance of the battery cell for a long period of time.

[0026] In particular, in the battery cell according to the present invention, a structure is introduced in which the attachment part is formed only on a part of the outer shell and the folded part and the attachment part is not formed on the cup part for receiving the electrode assembly, so that an empty space (air pocket) is not formed between the attachment part and the cup part for receiving the electrode assembly. Therefore, in the battery module including the battery cell according to the present invention, the gap filler can be in contact with the cup part for receiving the electrode assembly, thereby having the effect of improving the cooling efficiency of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 An electrode assembly, a housing, and a battery cell containing the electrode assembly in the housing are briefly shown according to an embodiment of the present invention;

[0028] Figure 2 Briefly show Figure 1 A cross section of the second sealing portion cut along line AA';

[0029] Figure 3 A battery cell with attached components bonded thereto according to an embodiment of the present invention is briefly shown;

[0030] Figure 4 A cross-sectional view schematically illustrates a battery module including a plurality of battery cells according to one embodiment of the present invention;

[0031] Figure 5 A photographic image and a bonding structure of the attaching member are briefly shown in which the attaching member is formed on the outer surface of the folded portion and the upper and lower portions of the sheet;

[0032] Figure 6 A photographic image schematically shows an attached component formed by a cup portion that does not house the electrode assembly on the outer surface of the sheet and the bonding structure of the attached component. DETAILED DESCRIPTION

[0033] The structural or functional descriptions of the embodiments disclosed in this specification or application are merely exemplary and are intended to illustrate embodiments according to the technical ideas disclosed herein. Embodiments according to the technical ideas of the present invention may be implemented in various ways in addition to the embodiments disclosed in this specification or application, and should not be construed as limiting the technical ideas of the present invention to the embodiments described in this specification or application.

[0034] The battery cell according to the present invention and the battery module including the battery cell are described in detail below.

[0035] The battery cell of the present invention comprises: an electrode assembly; a shell body, comprising a first sheet material having a cup portion for accommodating the electrode assembly and a second sheet material covering the first sheet material; a sealing portion formed by joining the inner surface of the first sheet material and the edge of the inner surface of the second sheet material; a folding portion formed by folding the sealing portion; and an attachment component bonded to one side of the folding portion and the outer surface of the second sheet material.

[0036] Figure 1 An electrode assembly, a housing, and a battery cell containing the electrode assembly in the housing according to an embodiment of the present invention are briefly shown.

[0037] Reference Figure 1 , the battery cell 100 according to an embodiment of the present invention includes an electrode assembly 10. The electrode assembly 10 may include a structure in which a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode are stacked. The positive electrode may include a positive electrode active material capable of inserting and desorbing lithium (Li) ions, and the negative electrode may include a negative electrode active material capable of absorbing and desorbing lithium (Li) ions. Moreover, the positive electrode and the negative electrode may further include a binder and a conductive material in the positive electrode active material and the negative electrode active material, respectively, to improve mechanical stability and conductivity. The separator may be configured to prevent an electrical short circuit between the positive electrode and the negative electrode and to generate an ion flow. The type of separator is not particularly limited, but may include a porous polymer film. The electrode assembly may be manufactured in a stacking (stacking) or zigzag stacking (zigzag stacking) manner by alternately stacking a plurality of positive electrodes and negative electrodes and providing a separator between the positive electrode and the negative electrode.

[0038] The battery cell 100 according to an embodiment of the present invention may further include an electrolyte. The electrolyte may be a non-aqueous electrolyte. The electrolyte may contain a lithium salt and an organic solvent. For example, the organic solvent may include one or more selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), dipropyl carbonate (DPC), vinylene carbonate (VC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, sulfolane, gamma-butyrolactone, propylene sulfide and tetrahydrofuran.

[0039] The battery cell 100 according to the embodiment of the present invention includes a housing body 20 , which includes: a first sheet 21 having a cup portion 21 - 1 for accommodating the electrode assembly 10 ; and a second sheet 22 covering the first sheet 21 .

[0040] The first sheet 21 and the second sheet 22 protect the electrode assembly 10 from the external environment. The first sheet 21 and the second sheet 22 may include a water-resistant resin, for example, a film formed by laminating polyolefin resin, metal, nylon resin, and polyterephthalate resin.

[0041] The first sheet 21 is formed with a cup portion 21 - 1 for accommodating the electrode assembly 10 . Figure 1 The cup portion 21 - 1 is shown to be in the shape of a rectangular parallelepiped with rounded corners, but is not limited thereto and may have various shapes according to the shape of the electrode assembly 10 .

[0042] The second sheet material 22 has a cover structure covering the first sheet material 21. Figure 1 The second sheet 22 is shown in FIG. 1 as having a planar shape, but is not limited thereto and may have various shapes according to the shape of the electrode assembly 10 .

[0043] The battery cell 100 according to the embodiment of the present invention includes a sealing portion 30 , which is formed by joining the inner surface of the first sheet 21 and the inner surface of the second sheet 22 at their edges.

[0044] The sealing portion 30 is formed by joining the edges of the inner surface of the first sheet 21 and the inner surface of the second sheet 22 to prevent the electrode assembly 10 contained in the first sheet 21 and the second sheet 22 from being separated from the outer shell body 20. The structures of the first sheet 21 and the second sheet 22 are not particularly limited, but the outer surface of the first sheet 21 and the outer surface of the second sheet 22 may be formed with a polyester terephthalate resin having excellent chemical and mechanical properties, and the inner surface of the first sheet 21 and the inner surface of the second sheet 22 may be formed with a polyolefin resin having excellent insulation. The method for forming the sealing portion 30 is not particularly limited, but it can be formed by heat-melting the polyolefin resin formed on the inner surface of the first sheet 21 and the inner surface of the second sheet 22.

[0045] The sealing portion 30 may include: a first sealing portion 31, which is joined in a state where an electrode tab 40 extending from the electrode assembly 10 is clamped; and a second sealing portion 32, which is joined in a state where the electrode tab 40 is not clamped. If the battery cell has a long life or is exposed to a high temperature environment, gas may be generated, and the second sealing portion 32 may be deformed or degassing due to the generated gas, and the danger of the battery cell 100 may increase. Therefore, in the battery cell 100 according to the present invention, in order to improve the stability of the second sealing portion 32, a folding portion and an attachment component are introduced into the second sealing portion 32.

[0046] The electrode tab 40 can be electrically connected to the electrode assembly. The electrode tab 40 can extend to the outside of the housing 20 that accommodates the electrode assembly 10 to become an electrode terminal. For example, the electrode tab electrically connected to multiple positive electrodes can become a positive terminal, and the electrode tab electrically connected to multiple negative electrodes can become a negative terminal. Figure 1 It is shown that the electrode tabs are formed on different sides, but the present invention is not limited thereto and the electrode tabs may be formed on the same side.

[0047] A battery cell according to an embodiment of the present invention includes a folded portion formed by folding a sealing portion.

[0048] Figure 2 Briefly show Figure 1 The cross section of the second sealing portion cut along the line AA'. Figure 2 , the folded portion 32 - 1 may be formed at the second sealing portion 32 .

[0049] The folded portion 32-1 can stably fix the second sealing portion 32 to suppress deformation of the second sealing portion 32 due to the gas generated inside the housing and delay venting. The folded portion 32-1 can be formed by folding the second sealing portion 32 toward the center direction (X) of the housing body more than once. For example, the folded portion 32-1 can be formed by folding the end of the second sealing portion 32 toward the center direction X of the housing body by 90 degrees, 180 degrees, 270 degrees, or 360 degrees.

[0050] The battery cell according to the embodiment of the present invention includes an attaching member 60. The attaching member 60 prevents the folded portion formed in the sealing portion from unfolding due to the gas pressure generated inside the housing, delays the venting phenomenon of the housing opening, and maintains the performance of the battery cell for a long time.

[0051] In particular, the battery cell according to the embodiment of the present invention includes an attachment component 60 bonded to one side of the folding portion 32-1 and the outside of the second sheet 22. More specifically, the folding portion 32-1 includes: a first folding surface 32-1-1, which is opposite to the outside of the second sheet 22; and a second folding surface 32-1-2, which is located at the outermost contour of the folding portion 32-1 with respect to the outer shell body, and the attachment component 60 can be bonded to the second folding surface 32-1-2.

[0052] In the past, in order to prevent the folding part from unfolding, an attachment component was formed on the upper and lower surfaces of the folding part and the sheet material for storing the electrode assembly. However, an empty space (air pocket) is formed between the attachment component and the sheet material for storing the electrode assembly, and the gap filler (gap filler) used to cool the battery cell is separated from the shell body due to the empty space, resulting in a problem of reduced cooling efficiency of the battery cell. In addition, although a method of introducing an attachment component between the folding part and the outside of the sheet material for storing the electrode assembly was explored, the problem of the folding part unfolding occurred when the gas pressure inside the shell increased.

[0053] In the present invention, the attaching member 60 is bonded to the outermost contour of the folded portion 32-1, and is bonded only to one side of the folded portion 32-1 and the outside of the second sheet 22. Therefore, the folded portion 32-1 can be prevented from unfolding, and no empty space (air pocket) is formed between the attaching member 60 and the cup portion for storing the electrode assembly, and in the battery module including the battery cell, the gap filler can be in contact with the cup portion for storing the electrode assembly, thereby having the effect of improving the cooling efficiency of the battery cell.

[0054] The second sealing portion 32 may be formed with a folded portion 32-1 in the entire area. In addition, the second sealing portion 32 may also include a joint portion 32-2 without forming the folded portion 32-1. If the second sealing portion 32 includes the joint portion 32-2, the attaching member 60 may not be bonded to the joint portion 32-2. The second folding surface 32-1-2 located at the outermost contour of the folding portion 32-1 is bent relative to one side of the joint portion 32-2, so that when the attaching member 60 is bonded to the folded portion 32-1 and not bonded to the joint portion 32-2 bent relative to the second folding surface 32-1-2, the bonding stability of the attaching member 60 is improved.

[0055] The folded portion 32-1 may be attached to the housing body 20 via the attaching member 60. The folded portion 32-1 may be attached to the housing body 20 via the attaching member 60, thereby reducing the overall thickness of the battery cell 100 and increasing the space usability in a battery module including a plurality of battery cells 100.

[0056] The attachment part 60 is not particularly limited as long as it is a material with adhesive force, but preferably, it may contain an insulating resin. The thickness (T) of the attachment part can be 0.01mm to 2.00mm. If the thickness (T) of the attachment part is less than 0.01mm, the durability is reduced, so there may be a problem of easy detachment from the folding surface. If the thickness (T) of the attachment part is greater than 2.00mm, there may be a problem that the thickness of the attachment part itself causes the overall thickness of the battery cell to increase. Therefore, the attachment part 60 can use an insulating tape with a thickness of 0.01mm to 2.00mm that does not increase the overall thickness of the battery cell 100 due to its own thickness and can provide insulation.

[0057] Figure 3 A battery cell with attached components bonded thereto according to an embodiment of the present invention is briefly shown.

[0058] Reference Figure 3 , a plurality of attaching members 60 may be arranged at intervals along the length direction Y of the second sealing portion 32. The attaching members 60 are arranged at intervals, so that even if the outer shell bulges due to the increase in gas pressure, the warping between the attaching member 60 and the folding portion 32-1 can be minimized, thereby having the effect of delaying the venting phenomenon of the sealing portion being opened.

[0059] A battery module according to an embodiment of the present invention includes battery cells as unit cells.

[0060] Figure 4 A cross-sectional view schematically illustrates a battery module including a plurality of battery cells according to an embodiment of the present invention.

[0061] Reference Figure 4 The battery module 200 may include a battery cell stack body in which a plurality of battery cells 100 are stacked and a heat sink 210. Figure 4 4 shows that a plurality of battery cells 100 are stacked in a horizontal direction to form a battery cell stack, but the present invention is not limited thereto and a plurality of battery cells 100 may be stacked in a vertical direction as required.

[0062] The heat dissipation plate 210 may be disposed on the upper part, the lower part, the side part, etc. of the battery cell stack. The heat dissipation plate 210 may be a cooling plate, and the plurality of battery cells 100 may be cooled by the heat dissipation plate 210 .

[0063] The battery module 200 may include a gap filler disposed between the battery cell 100 and the heat sink 210. The gap filler may be used to improve the contact between the battery cell 100 and the heat sink 210, and may include a thermally conductive adhesive as required. The gap filler may be in contact with the attachment component 60 of the battery cell 100 and the outer surface of the first sheet 21.

[0064] According to the present invention, the attachment component of the battery cell is bonded to the outermost contour of the folded portion and only to one side of the folded portion and the outside of the second sheet, so no empty space (air pocket) is formed between the attachment component and the cup portion for storing the electrode assembly. Therefore, the gap filler can contact the cup portion of the electrode assembly for storing the battery cell, thereby having the effect of improving the cooling efficiency of the heat sink for the battery cell.

[0065] Example

[0066] An experiment was conducted to confirm the heat dissipation effect based on the form of the attachment part bonded to the sealing part of the battery cell. The difference in thermal resistance (K / W) values ​​in the battery module was confirmed for the battery cell in which the attachment part was formed on the outer surface of the folded part and the upper and lower parts of the sheet as the first attachment part and the battery cell in which the attachment part was not formed on the cup part storing the electrode assembly as the second attachment part.

[0067] Figure 5 A photographic image of the first attachment member and the bonding structure of the attachment member are briefly shown in FIG. Figure 6 2 and 3 schematically show a photographic image of a second attachment member and a bonding structure of the attachment member.

[0068] The thermal resistance was measured under the conditions of 5 LPM initial flow rate of cooling water flowing from a heat sink outside the battery module, 15°C initial temperature, and 80 A current. Table 1 below shows the measurement results of the upper thermal resistance, lower thermal resistance, and total thermal resistance of the battery module including the battery cells of the first attachment form and the battery cells of the second attachment form.

[0069]

Table 1

[0070]

[0071] According to Table 1, it can be confirmed that the upper thermal resistance value and the total thermal resistance value of the battery module including the battery cell of the second attachment form are lower than the upper thermal resistance value and the total thermal resistance value of the battery module including the battery cell of the first attachment form. That is, it can be confirmed that the battery module including the battery cell of the second attachment form has a higher cooling efficiency than the battery cell of the first attachment form in which an empty space (air pocket) is formed between the attachment member and the cup portion for storing the electrode assembly because no empty space (air pocket) is formed between the attachment member and the cup portion for storing the electrode assembly.

Claims

1. A battery cell, comprising: Electrode assembly; The housing body includes a first sheet material having a cup portion for accommodating the electrode assembly and a second sheet material covering the first sheet material; A sealing portion formed by joining the inner surface of the first sheet material and the inner surface of the second sheet material at their edges; a folded portion formed by folding the sealing portion; as well as The attaching component is bonded to one side of the folded portion and the outer surface of the second sheet material.

2. The battery cell according to claim 1, wherein the sealing portion comprises: A first sealing portion is joined in a state of sandwiching an electrode tab extending from the electrode assembly; as well as The second sealing portion is joined without sandwiching the electrode tab. The folded portion is formed at the second sealing portion. 3 . The battery cell according to claim 2 , wherein the second sealing portion further comprises a joining portion where the folded portion is not formed. The battery cell according to claim 3 , wherein the attachment member is not adhered to the joint portion. The battery cell according to claim 1 , wherein the folded portion is tightly attached to the outer shell body through the attaching component. 6 . The battery cell according to claim 1 , wherein the folded portion is formed by folding the sealing portion toward the center of the case body one or more times.

7. The battery cell according to claim 1, wherein the folded portion comprises: a first folding surface, opposite to the outer surface of the second sheet; as well as The second folding surface is located at the outermost contour of the folding portion with the shell body as a reference, The attaching component is bonded to the second folding surface.

8. The battery cell according to claim 1, wherein the attaching member comprises an insulating resin. 9 . The battery cell according to claim 1 , wherein the thickness of the attachment member is 0.01 mm to 2.00 mm. 10 . The battery cell according to claim 2 , wherein a plurality of the attaching members are arranged at intervals along a longitudinal direction of the second sealing portion.

11. A battery module comprising the battery cell according to claim 1 as a unit cell. 12 . The battery module according to claim 11 , comprising a heat sink. 13 . The battery module according to claim 12 , comprising a gap filler disposed between the battery cells and the heat sink. 14 . The battery module according to claim 13 , wherein the gap filler is in contact with an attachment member of the battery cell and an outer surface of the first sheet of the battery cell.

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