Pouch-type battery cell with improved safety and battery module including the same

Abstract

The present invention relates to a pouch-type battery cell with improved safety and a battery module including the same, and more particularly, to a pouch-type battery cell including a first cell case and a second cell case made of a laminate sheet including an inner coating layer, a metal layer, and an outer coating layer, and having edges sealed by heat sealing, an electrode assembly housed in the first cell case and the second cell case, a positive electrode lead and a negative electrode lead connected to the electrode assembly on one side and arranged to protrude outside the first cell case and the second cell case on the other side, and a pressing member surrounding the sealing portion formed by heat sealing, and a battery module including the same.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0004314, filed on January 11, 2022, and all of the contents disclosed in the Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a pouch-type battery cell with improved safety and charge / discharge output performance and a battery module including the same. Specifically, the present invention relates to a pouch-type battery cell with improved safety and a battery module including the same, which has a structure capable of preventing and delaying gas venting and enabling rapid heat dissipation by providing a pressing member at a sealing portion of the battery cell and a heat transfer pad at a battery module case.

Background Art

[0003] As the technology development and demand for mobile devices such as smartphones, notebook PCs, and digital cameras increase, technologies related to rechargeable secondary batteries are being actively studied. In addition, secondary batteries are alternative energy sources for fossil fuels that generate air pollutants, and are applied to electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and energy storage devices (ESSs).

[0004] Currently, widely used types of secondary batteries include lithium-ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel metal hydride batteries, nickel zinc batteries, and the like. Such unit secondary battery cells are generally configured to form a battery module by connecting a plurality of battery cells in series or in parallel according to a required output voltage or charge / discharge capacity.

[0005] In particular, the use amount of pouch-type lithium-ion batteries having a structure in which a stacked or stacked-folding type electrode assembly is built in a pouch-type battery case made of an aluminum laminate sheet is gradually increasing due to advantages such as low manufacturing cost and high energy density.

[0006] FIG. 1 is a schematic view of a pouch-type battery cell according to the prior art. In the pouch-type battery cell according to the prior art, an electrode assembly is housed in a storage space formed by a first cell case 11 and a second cell case 12. Then, after the electrode tabs extending from the electrode assembly are electrically connected to the positive electrode lead 14 and the negative electrode lead 15, they are positioned so as to be exposed outside the cell case.

[0007] Here, the edges where the first cell case 11 and the second cell case 12 overlap each other are sealed by heat fusion, so that the electrode assembly is structured to be blocked from contact with the outside.

[0008] However, when the temperature of the battery cell rises due to repeated charge and discharge processes or event occurrence, the adhesion performance of the heat fusion sealing part deteriorates. In particular, since the temperature near the electrode lead connected to the electrode tab rises the most, the sealing part where the electrode lead is located is the most vulnerable. Considering the recent development trend of electric vehicles, it is necessary to develop a battery cell that can be stably used even at a high current such as rapid charging.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] In order to solve the above problems, an object of the present invention is to provide a pouch-type battery cell with improved safety that can enhance the adhesion strength of the sealing part and a battery module including the same.

[0011] In addition, since the present invention can rapidly dissipate the heat generated in the battery cell, it is possible to use a large charge and discharge current to shorten the charging time of the vehicle, and further improve the charge and discharge output performance so that higher output can be used. An object of the present invention is to provide a pouch-type battery cell and a battery module including the same.

Means for Solving the Problems

[0012] The pouch-type battery cell according to the present invention for achieving such an object is composed of a laminate sheet including an inner coating layer, a metal layer, and an outer coating layer, and a first cell case (210) and a second cell case (220) whose edges are sealed by heat fusion, an electrode assembly housed in the first cell case (210) and the second cell case (220), a positive electrode lead (240) and a negative electrode lead (250) whose one side is connected to the electrode assembly and the other side is arranged to protrude outside the first cell case (210) and the second cell case (220), and a pressing member (260) surrounding a sealing portion formed by heat fusion.

[0013] In the pouch-type battery cell according to the present invention, the pressing member (260) is arranged so as to surround the sealing portion where the positive electrode lead (240) or the negative electrode lead (250) is located.

[0014] In the pouch-type battery cell according to the present invention, the pressing member (260) has a shape in which a hexahedral bar having a predetermined thickness and width is folded.

[0015] In the pouch-type battery cell according to the present invention, the pressing member (260) is composed of an inner layer (261) that is in close contact with the outer surface of the sealing portion and an outer layer (262) that is located outside the inner layer (261).

[0016] In the pouch-type battery cell according to the present invention, the inner layer (261) is made of a resin capable of heat transfer, and the outer layer (262) is made of a metal material.

[0017] In addition, the present invention includes a module case (100) including a bottom plate (110), a pair of side plates (120), and a top plate (130), a plurality of battery cells (200) housed inside the module case (100), and a plurality of bus bars (300) for connecting the plurality of battery cells (200) in series or in parallel, and the battery cell (200) is the pouch-type battery cell described above.

[0018] In addition, in the battery module according to the present invention, the inner surface of the bottom plate (110) further includes a heat transfer pad (140).

[0019] In addition, in the battery module according to the present invention, one end of the pressing member (260) of the battery cell (200) is positioned so as to be in close contact with the heat transfer pad (140).

[0020] In addition, in the battery module according to the present invention, the bottom plate (110) is made of a metal material.

[0021] In addition, the present invention provides a battery pack including the battery module described above.

Advantages of the Invention

[0022] According to the pouch-type battery cell with improved safety of the present invention, since it is provided with a pressing member surrounding the sealing portion where the electrode lead is located, gas venting can be prevented or delayed, and thus the safety of the battery cell can be enhanced and the life can be extended.

[0023] In addition, according to the battery module with improved safety of the present invention, the battery cell provided with a pressing member made of a heat-conductive material is arranged to be in contact with the heat transfer pad provided in the metal module case, so there is an advantage that rapid heat dissipation is possible.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0025] In this application, terms such as "include", "have", or "comprise" are intended to specify the presence of the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and one or more other features, numbers, steps, operations, components, parts, or combinations thereof, etc. It should be understood that the possibility of the presence or addition is not precluded in advance.

[0026] Also, the same reference numerals are used for parts having similar functions and actions throughout the drawings. Throughout the specification, when a part is said to be connected to another part, this includes not only the case where they are directly connected, but also the case where they are indirectly connected with other elements interposed therebetween. Also, including a certain component means that, unless otherwise specified to the contrary, it does not exclude other components and can further include other components.

[0027] Hereinafter, a pouch-type battery cell with improved safety according to the present invention and a battery module including the same will be described.

[0028] FIG. 2 is a perspective view of a battery module according to a preferred embodiment of the present invention, FIG. 3 is a front view of the battery module shown in FIG. 2, and FIG. 4 is a perspective view of the battery module shown in FIG. 2 cut in the vertical direction. Further, FIG. 5 is a perspective view of the battery module shown in FIG. 2 cut in the horizontal direction, and FIG. 6 is an internal perspective view of the battery module shown in FIG. 2.

[0029] Referring to FIGS. 2 to 6, the battery module according to the present invention includes a module case 100, a plurality of battery cells 200, a plurality of bus bars 300, and a bus bar frame 400.

[0030] First, the module case 100 is for housing the battery cells 200, the bus bars 300, and the bus bar frame 400 and protecting them from external impacts, etc., and can have a substantially hexahedral shape.

[0031] Specifically, the module case 100 made of a metal material such as aluminum can be composed of a bottom plate 110 and an upper plate 130 that support and protect the lower and upper parts of the battery cells 200 respectively, a pair of side plates 120 that support the sides, and a heat transfer pad 140.

[0032] These bottom plate 110, a pair of side plates 120, and upper plate 130 can be manufactured integrally or manufactured separately and then fixed by known means such as bolts. Although a front plate and a rear plate are not shown in the drawings, a front plate and a rear plate can be further provided as needed.

[0033] The heat transfer pad 140 is disposed on the inner surface of the bottom plate 110, more specifically, at the locations where the positive electrode lead 240 and the negative electrode lead 250 of the battery cell 200 are located. The lower end of the pressing member 260 of the battery cell 200 is disposed in close contact with the upper surface of the heat transfer pad 140.

[0034] Therefore, the heat generated in the battery cell 200 is transmitted to the pressing member 260 and then sequentially passes through the heat transfer pad 140 and the bottom plate 110 made of a metal material, so that the heat dissipation effect of the battery module can be enhanced. Further, the heat transfer pad 140 can support the load of the pressing member 260 and contribute to reducing the tolerance that may occur during assembly.

[0035] Here, the material of the heat transfer pad 140 is not particularly limited as long as it can perform the above functions. For example, it can be a known heat conductive material (TIM, Thermal Interface Material).

[0036] In the drawings, the heat transfer pads 140 are shown as being located in front of and behind the bottom plate 110, respectively. However, in the case of a unidirectional battery cell in which the positive electrode lead and the negative electrode lead are exposed in the same direction, it may be provided only on the side where the leads are arranged.

[0037] The battery cells 200, more specifically, the pouch-type battery cells, housed inside the module case 100 are vertically stood up and then stacked side by side.

[0038] FIG. 7 is a perspective view of a battery cell according to a preferred embodiment of the present invention, FIG. 8 is an exploded perspective view of the battery cell shown in FIG. 7, and FIG. 9 is an enlarged perspective view of a pressing member attached to the battery cell.

[0039] As shown in FIGS. 7 to 9, a battery cell 200 according to the present invention includes a cell case, an electrode assembly (not shown) housed inside the cell case, a sealing portion 230 at the edge of the cell case, a pair of electrode tabs (not shown), a pair of electrode leads electrically connected to the electrode tabs on one side and protruding outside the cell case on the other side, an insulating film (not shown), and a pressing member 260.

[0040] Specifically, the cell case is composed of a first cell case 210 and a second cell case 220, made of a laminate sheet including an outer coating layer, a metal layer, and an inner coating layer, and a pocket-shaped space portion is formed so as to be able to house the electrode assembly.

[0041] Since the inner coating layer comes into direct contact with the electrode assembly, it must have insulation and electrolyte resistance, and also must have sealing properties for external sealing, that is, the sealing portion where the inner layers are thermally bonded must have excellent thermal bonding strength.

[0042] As the material for such an inner coating layer, it can be selected from polyolefin resins such as polypropylene, polyethylene, polyethylene acrylic acid, and polybutylene, polyurethane resins, and polyimide resins, which have excellent chemical resistance and good sealing properties, but are not limited thereto. Polypropylene, which is excellent in mechanical physical properties such as tensile strength, rigidity, surface hardness, and impact resistance, and chemical resistance, is most preferable.

[0043] The metal layer in contact with the inner coating layer corresponds to a barrier layer that prevents moisture and various gases from penetrating into the battery from the outside. As a preferable material for such a metal layer, an aluminum thin film that is light and has excellent formability can be used.

[0044] On the other side of the metal layer, an external coating layer is provided. Such an external coating layer can use a heat-resistant polymer excellent in tensile strength, moisture vapor barrier property, and air permeation barrier property so as to ensure heat resistance and chemical resistance while protecting the electrode assembly. For example, nylon or polyethylene terephthalate can be used, but it is not limited thereto.

[0045] On the other hand, the electrode assembly housed inside the first cell case 210 and the second cell case 220 can be classified into a stack-type electrode assembly in which a plurality of electrodes are laminated, a jelly-roll type electrode assembly wound in a state where a separator is interposed between a positive electrode and a negative electrode, a lamination-stack type electrode assembly in which a plurality of unit cells are laminated, and a stack-folding type electrode assembly wound in a state where a unit cell is located on a separator sheet.

[0046] A unit cell is manufactured to manufacture the above-described lamination-stack type electrode assembly and stack-folding type electrode assembly. The unit cell can have a form of a mono-cell in which a separator is interposed between a positive electrode and a negative electrode, and a form of a bi-cell in which a positive electrode, a negative electrode, and a positive electrode, or a negative electrode, a positive electrode, and a negative electrode are laminated and a separator is interposed between the positive electrode and the negative electrode.

[0047] The electrode assembly according to the present invention can have a structure in which a negative electrode / separator / positive electrode / separator / negative electrode are laminated. Needless to say, the number of positive electrodes and negative electrodes constituting the electrode assembly can be freely set and used. Also, a lamination-stack type electrode assembly in which a plurality of unit cells are laminated can be used, and the structure of the electrode assembly can be applied to any of the electrode assemblies described in this specification.

[0048] The positive and negative electrodes of the electrode assembly body are each provided with a positive electrode tab and a negative electrode tab, and this pair of tabs are each connected to the positive electrode lead 240 and the negative electrode lead 250 by spot welding or the like, and are arranged so as to protrude a predetermined length outside the cell case.

[0049] And the insulating film is located on the upper and lower surfaces of the pair of electrode leads, more specifically, at the sealing portion 230 where the first cell case 210 and the second cell case 220 are heat-sealed.

[0050] Therefore, it prevents the electricity generated from the electrode assembly from flowing into the cell case through the electrode leads, and also maintains the sealing state between the electrode leads and the cell case. Here, the insulating film is preferably made of a non-conductive material that does not conduct electricity. Generally, an insulating tape that is easy to adhere to the electrode leads and has a relatively thin thickness is often used, but it is not limited to this.

[0051] In the drawings, the positive electrode lead 240 and the negative electrode lead 250 are shown as a two-way battery cell located on opposite sides of each other, but these pair of electrode leads may be a one-way battery cell arranged in the same direction.

[0052] Next, the pressing member 260 will be described. The pressing member 260 is arranged so as to surround the sealing portion 230 formed by heat-sealing, more preferably the sealing portion 230 corresponding to the so-called terrace portion where the positive electrode lead 240 and the negative electrode lead 250 are located.

[0053] Such a pressing member 260 has a shape in which a long hexahedral bar having a predetermined thickness and width is folded, and has a multi-layer structure including an inner layer 261 and an outer layer 262 located outside the inner layer 261.

[0054] Here, the inner layer 261 comes into close contact with the outer surface of the sealing portion and can be made of a resin capable of heat transfer, for example, the same material as the heat transfer pad 140 described above. And the outer layer 262 is preferably made of a metal material such as aluminum or copper.

[0055] When using the pressing member 260 having the above-described configuration, since the sealing portion can be maintained in a state of being pressed by the outer layer 262 of the hard metal material, it is possible to compensate for the decrease in the adhesion performance of the inner coating layer even in a high-temperature environment.

[0056] Also, since the inner layer 261 of the pressing member 260 is made of a resin having a predetermined elasticity, it can not only prevent damage to the cell case even when it is in close contact with the outer surface of the sealing portion 230, but also absorb the thickness tolerance.

[0057] Furthermore, since the inner layer 261 of the pressing member 260 is capable of heat transfer and is arranged so that the lower end portion of the pressing member 260 is in close contact with the heat transfer pad 140 located on the bottom plate 110, the heat dissipation effect of the battery cell 200 can be enhanced.

[0058] On the other hand, as shown in FIGS. 7 to 9, it is preferable that the bent portion (the lower end portion in FIG. 9) of the pressing member 260 is located on the lower side. This is to increase the area in contact with the heat transfer pad 140 as much as possible.

[0059] Also, the bus bar and the bus bar frame will be described with reference to FIGS. 2 to 6. The bus bar 300 is for connecting a plurality of battery cells 200 housed inside the module case 100 in series or in parallel.

[0060] That is, the bus bar 300 is a conductor having a low impedance and a high current capacity, and a plurality of bus bars 300 are arranged side by side in the direction in which the plurality of battery cells 200 are stacked to connect the battery cells 200 in series or in parallel.

[0061] Although the bus bar 300 in the present invention is exemplified as having a plate-like structure with a constant thickness, it is not limited thereto, and can be implemented by changing to various structures capable of electrical connection.

[0062] The bus bar frame 400 is fixed to the module case 100 while supporting the bus bar 300. Specifically, the lead of the battery cell 200 passes through the slit of the bus bar 300 and is then bent, and thereafter is fixed to the bus bar 300 by known fixing means such as laser welding and resistance welding. The bus bar frame 400 is positioned between the battery cell 200 and the bus bar 300 so that these battery cells 200 and bus bar 300 can be stably supported.

[0063] The battery module described above can constitute a battery pack and can also be applied to various devices.

[0064] Although the specific part of the content of the present invention has been described in detail above, such a specific technology is only a preferred embodiment for those having ordinary knowledge in the art, and the scope of the present invention is not limited thereby. It is obvious to those skilled in the art that various changes and modifications are possible within the scope of the present invention and the scope of the technical idea, and it goes without saying that such deformations and modifications also belong to the scope of the appended claims.

Explanation of Reference Numerals

[0065] 100 Module case 110 Bottom plate 120 Side plate 130 Top plate 140 Heat transfer member 200 Battery cell 210 First cell case 220 Second cell case 230 Sealing part 240 Positive electrode lead 250 Negative electrode lead 260 Pressing member 261 Outer layer 262 Inner layer 300 Bus bar 400 Bus bar frame

Claims

1. It consists of a laminated sheet including an inner coating layer, a metal layer, and an outer coating layer, a first cell case and a second cell case whose edges are sealed by heat fusion, and an electrode assembly housed in the first cell case and the second cell case, a positive electrode lead and a negative electrode lead, one side of which is connected to the electrode assembly and the other side of which is arranged to protrude outside the first cell case and the second cell case, a pressing member that surrounds a sealing portion formed by heat fusion and maintains the state of pressing the sealing portion, and the pressing member has a shape in which a hexahedral bar having a predetermined thickness and width is folded, a pouch-type battery cell.

2. The pouch-type battery cell according to claim 1, wherein the pressing member is arranged to surround a sealing portion where the positive electrode lead or the negative electrode lead is located.

3. The pouch-type battery cell according to claim 1, wherein the pressing member includes an inner layer that is in close contact with an outer surface of the sealing portion and an outer layer that is located outside the inner layer.

4. The pouch-type battery cell according to claim 3, wherein the inner layer is made of a resin capable of heat transfer, and the outer layer is made of a metal material.

5. A module case including a bottom plate, a pair of side plates, and an upper plate, a plurality of battery cells housed inside the module case, a plurality of bus bars for connecting the plurality of battery cells in series or in parallel, and the battery cell is the pouch-type battery cell according to any one of claims 1 to 4, a battery module.

6. The battery module according to claim 5, further comprising a heat transfer pad on an inner surface of the bottom plate.

7. The battery module according to claim 6, wherein one end portion of the pressing member of the battery cell is positioned to be in close contact with the heat transfer pad.

8. The battery module according to claim 7, wherein the bottom plate is made of a metal material.

9. A battery pack including the battery module according to claim 5.

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