Battery pack

Abstract

The present invention relates to a battery pack accommodating a cell assembly, comprising: a pack case in which the cell assembly is seated; and an upper case coupled to the pack case to cover an upper portion of the cell assembly seated inside the pack case, wherein the upper case includes an elastic member at a lower end thereof that applies pressure to an upper portion of the cell assembly seated in the pack case.

Description

[Technical Field]

[0001] The present invention relates to a battery pack in which a cell assembly is housed.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0107108, filed on August 16, 2023, and all contents disclosed in the documents of said Korean patent application are incorporated herein by reference. [Background technology]

[0003] In general, a cell is composed of an electrode assembly in which electrodes and separators are alternately stacked, electrode leads connected to the electrodes of the electrode assembly, a case from which the electrode leads extend to the outside and which surrounds the electrode assembly, and an electrolyte filled inside the case together with the electrode assembly.

[0004] The cells can be roughly classified into cylindrical cells, pouch cells, and prismatic cells depending on the shape of the case.

[0005] While a cell may be used alone, it is generally configured with a number of cells electrically connected in series and / or parallel to one another. In particular, a number of cells electrically connected to one another form a cell stack. The cell stack can also be housed inside a module frame to form a single cell assembly.

[0006] FIG. 1 shows a cell assembly 20 in which pouch-type cells 24 are housed, and FIG. 2 shows a cell assembly 20 in which prismatic cells 24 are housed.

[0007] 1, the pouch-type cells 24 are arranged so that the electrode leads 26 of each cell 24 are located on the side. Therefore, the cell assembly 20 can have terminals formed on the side corresponding to the electrode leads 26 of the housed cells 24.

[0008] In the cell assembly 20 accommodating the pouch-type cells 24, end plates 21 may be coupled to the front and rear surfaces of the cell stack 25 to protect the terminals. Therefore, in the cell assembly 20 accommodating the pouch-type cells 24, external terminals electrically connected to the cell stack 25 may be provided on the end plates 21.

[0009] 2, the prismatic cells 24 are arranged such that the electrode leads 26 of each cell 24 face upward. Therefore, the cell assembly 20 may have terminals formed on the upper portion thereof corresponding to the electrode leads 26 of the accommodated cells 24. Therefore, the cell assembly 20 accommodating the prismatic cells 24 may have external terminals electrically connected to the cell stack 25 provided on the module frame 22 located on the upper portion of the cell stack 25.

[0010] The cell assembly 20 housing the prismatic cell 24 does not have a configuration such as an end plate 21 added by the electrode lead 26 provided on the side, as shown in FIG.

[0011] As shown in Figures 1 and 2 above, the cell assemblies 20 differ slightly depending on the shape of the cells 24 housed inside, but are the same in that the internal cell stack 25 is surrounded and protected by the module frame 22.

[0012] Two or more cell assemblies 20 used in products requiring high power output, such as electric vehicles, can be electrically connected to each other in series and / or parallel to form a higher level device, such as a battery pack.

[0013] 3 shows a conventional battery pack and a cell assembly 20 housed therein. The battery pack may include a pack case 10 into which the cell assembly 20 is directly inserted and housed, and an upper case coupled to the pack case 10 so that the internal space of the pack case 10 can be isolated from the outside. Each cell assembly 20 is housed in a partitioned space inside the pack case 10, as shown in FIG. 3.

[0014] Meanwhile, in a cell assembly 20 including multiple cells 24 densely packed in a small space, problems such as short circuits may occur in some of the cells 24, causing a sustained temperature rise and resulting in a thermal runaway phenomenon in which the temperature of the cells 24 exceeds a critical temperature. Hot gas and spark particles may be ejected from the thermally runaway cells 24. (Here, spark particles refer to active material detached from electrodes inside the cells 24, molten aluminum particles, etc.) Furthermore, in some cases, flames may break out in some of the cells 24.

[0015] If gas is generated inside the cell assembly 20 surrounded by the module frame 22 and the end plate 21 as described above, the gas pressure may cause the cell assembly 20 to explode, and the explosion may cause flames and heat to be transferred to other cell assemblies 20. To solve the above-mentioned explosion problem, the conventional cell assembly 20 may be formed with an opening hole 23 through which the gas can be discharged.

[0016] 4 shows a conventional cell assembly 20 employing an opening hole 23. The cell assembly 20 employing the opening hole 23 can quickly exhaust high-temperature gas even if the internal cells 24 undergo thermal runaway and generate high-temperature gas, thereby preventing internal pressure from being generated.

[0017] However, when the opening holes 23 are formed in the cell assemblies 20 as described above, there is a frequent problem that spark particles and flames generated in the cells 24 are transferred to other cell assemblies 20 through the opening holes 23. Summary of the Invention [Problem to be solved by the invention]

[0018] Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a battery pack having a structure that can effectively discharge gas generated inside to the outside in a thermal runaway situation.

[0019] Another object of the present invention is to provide a battery pack having a structure that can delay the progress of heat transfer to other cell assemblies even if a thermal runaway phenomenon occurs in any one cell assembly housed therein.

[0020] Other objects and advantages of the present invention can be understood from the following description and become more apparent from the embodiments of the present invention, and it is easily understood that the objects and advantages of the present invention can be realized by the means and combinations thereof as set forth in the claims. [Means for solving the problem]

[0021] In accordance with the present invention, a battery pack is provided that houses a cell assembly.

[0022] The battery pack includes a pack case in which a cell assembly is mounted, and an upper case coupled to the pack case to cover an upper portion of the cell assembly mounted inside the pack case, and the upper case includes an elastic member at a lower end thereof that applies pressure to an upper portion of the cell assembly mounted in the pack case.

[0023] The cell assembly may include a cell stack including a plurality of cells, and a module frame surrounding at least one side of the cell stack.

[0024] The module frame may include an opening hole that exposes the internal cell stack to the outside.

[0025] The opening hole may be formed in one of a circular shape and a polygonal shape.

[0026] The opening hole may be formed to extend along one of the length direction and the width direction of the cell assembly.

[0027] The cell assembly may further include a protection sheet attached to the surface of the module frame to cover the opening hole.

[0028] The elastic member of the upper case may be formed at a position where no opening hole of the cell assembly is provided.

[0029] The opening hole may be formed on a module frame located on top of the cell assembly.

[0030] The protective sheet may have a porous structure containing a plurality of voids that selectively allow gas to pass through.

[0031] The protective sheet may have a structure that does not form voids so that gas cannot pass through.

[0032] The protective sheet may have electrical insulating properties.

[0033] The protective sheet can be heat resistant and flame retardant. [Effects of the Invention]

[0034] According to the present invention, even if a thermal runaway phenomenon occurs in one cell assembly in a battery pack containing a plurality of cell assemblies, heat transfer to adjacent cell assemblies can be minimized, thereby improving safety against explosion. [Brief explanation of the drawings]

[0035] [Figure 1] 1 shows a conventional cell assembly including a pouch-type cell. [Figure 2] 1 shows a conventional cell assembly including prismatic cells. [Figure 3] 1 shows a conventional battery pack and the cell assembly contained therein. [Figure 4] 1 shows a conventional cell assembly. [Figure 5] 1 shows a battery pack according to a first embodiment of the present invention. [Figure 6] 1 illustrates a cell assembly of the present invention. [Figure 7] This shows the cell assembly of FIG. 6 with the protective sheet separated. [Figure 8] FIG. 2 is a bottom perspective view of the upper case. [Figure 9] In the battery pack of Figure 5, the upper case is shown with hidden lines to show the elastic member. [Figure 10] 10 shows the upper case and pack case of FIG. 9 joined together. [Figure 11] 1 is a simplified cross-sectional view of a battery pack in which one cell assembly is mounted. [Figure 12] This shows the movement of gas generated in the cell stack when thermal runaway occurs in the battery pack shown in Figure 11 above. [Figure 13] 1 shows a battery pack according to a second embodiment of the present invention. [Figure 14] The cell assembly accommodated in FIG. 13 is shown. [Figure 15]This shows the cell assembly of FIG. 14 with the protective sheet separated. DETAILED DESCRIPTION OF THE INVENTION

[0036] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Before that, the terms and words used in the specification and claims are not to be construed as being limited to their ordinary or dictionary meanings, but are to be construed as meanings and concepts that are consistent with the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concepts of the terms in order to best describe his own invention.

[0037] Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and there may be various equivalents and modifications that can replace them at the time of this application.

[0038] Furthermore, in the description of the present invention, if it is determined that a specific description of related publicly known configurations or functions may obscure the gist of the present invention, the detailed description will be omitted.

[0039] The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art, and therefore the shapes and sizes of components in the drawings may be exaggerated, omitted, or shown in a schematic manner for clearer explanation. Therefore, the sizes and proportions of each component do not completely reflect the actual sizes and proportions.

[0040] The present invention relates to a battery pack accommodating a plurality of cell assemblies, characterized in that an elastic member is applied to pressurize the upper portion of the accommodated cell assemblies.

[0041] 5 to 12 relate to a battery pack according to a first embodiment of the present invention, and FIGS. 13 to 15 relate to a battery pack according to a second embodiment of the present invention.

[0042] Hereinafter, specific embodiments of the battery pack of the present invention will be described in detail with reference to the accompanying drawings. For reference, the directions of front, back, up, down, left, and right used in the following description to designate relative positions are intended to facilitate understanding of the invention, and unless otherwise specified, are based on the directions shown in the drawings.

[0043] Furthermore, the cell assembly of the present invention may be in a form in which pouch-type cells are housed as shown in FIG. 1 or in a form in which prismatic cells are housed as shown in FIG. 2, but for convenience, the following description will focus on the form in which pouch-type cells are housed as shown in FIG. 1.

[0044] (First embodiment) FIG. 5 shows a battery pack according to a first embodiment of the present invention.

[0045] The battery pack includes a pack case 100 in which the cell assembly 300 is mounted, and an upper case 200 coupled to the pack case 100 to cover the upper part of the cell assembly 300 mounted inside the pack case 100.

[0046] The cell assembly 300 accommodated in the battery pack of the present invention is characterized in that an opening hole 321 is formed on one side thereof and a protective sheet 340 is provided to cover the opening hole 321 .

[0047] FIG. 6 shows a cell assembly 300 of the present invention, and FIG. 7 shows the cell assembly 300 of FIG. 6 with the protective sheet 340 separated.

[0048] The cell assembly 300 includes a cell stack 310 including a plurality of cells, and a module frame 320 surrounding at least one side of the cell stack 310 .

[0049] As shown in FIG. 6, the cell assembly 300 may further include an end plate 330 that protects the cell stack housed therein from external impacts and on which external terminals electrically connected to the cell stack are located.

[0050] As shown in FIG. 7, the module frame 320 includes a plurality of opening holes 321 that are opened to expose the internal cell stack 310 to the outside.

[0051] The opening hole 321 is formed to prevent the cell assembly 300 from exploding due to an increase in the pressure of the gas g inside the cell assembly 300 when high-temperature gas g is generated due to thermal runaway of the housed cell stack 310. That is, the opening hole 321 serves as a passage through which the gas g generated due to thermal runaway of the cell stack 310 can escape to the outside.

[0052] The opening hole 321 is formed on a module frame 320 located above the cell assembly 300 of FIG.

[0053] The opening hole 321 may be formed in one of a circular shape and a polygonal shape.

[0054] The cell assembly 300 of the present invention further includes a protection sheet 340 attached to the surface of the module frame 320 to cover the opening hole 321 .

[0055] The protective sheet 340 covers one side of the module frame 320 where the opening hole 321 is formed, and serves to prevent flames and spark particles from escaping through the opening hole 321.

[0056] In addition, when any one of the housed cell assemblies 300 experiences thermal runaway and generates flames and gases, the protective sheet 340 prevents the flames and gases from flowing into the opening holes 321 of the other normal cell assemblies 300.

[0057] The protective sheet 340 preferably includes a material that is heat-resistant and flame-retardant so that it is not damaged by the high-temperature gas g and does not burn in a flame.

[0058] Moreover, the protective sheet 340 preferably includes a material having electrical insulation properties.

[0059] The protective sheet 340 may have a structure without voids so that gas does not pass through, or may have a porous structure including a plurality of voids that allow gas to selectively pass through.

[0060] The protective sheet 340, which has a structure without voids, is attached to the cell assembly 300 so as to seal the opening hole 321. Therefore, in the case of a cell assembly 300 to which the protective sheet 340 is normally attached, gases and flames are unlikely to pass through the opening hole 321.

[0061] The protective sheet 340 has a limit pressure beyond which it will not deform due to external pressure, and may be damaged when pressure exceeding the limit pressure is applied. For example, the protective sheet 340 sealing the opening hole 321 may be partially damaged when the pressure inside the cell assembly reaches the limit pressure range, releasing gas and flames. In this case, a fracture line may be applied to the protective sheet 340 to intentionally open a desired portion first.

[0062] The protective sheet 340 having the voids formed therein allows the gas g generated due to thermal runaway of the cells to pass through, but does not allow spark particles and the like that may be generated together with the gas g to pass through.

[0063] The pack case 100 includes a base plate 110 that supports the lower part of the cell assembly 300, and side beams 120 that are coupled to the edges of the base plate 110 to support the sides of the cell assembly 300.

[0064] In addition, the pack case 100 may include a cross beam 130 whose lower end is connected to the base plate 110 to define an internal space.

[0065] The plurality of cell assemblies 300 may be arranged and seated so as to be separated from one another in the internal space of the pack case 100 partitioned by the cross beams 130. In this case, each cell assembly 300 is arranged so that the opening hole 321 and the protective sheet 340 face upward, as shown in FIG.

[0066] As shown in FIG. 5, the upper case 200 is coupled to the upper end of the side beam 120 of the pack case 100 so as to cover the upper part of the cell assembly 300 mounted inside the pack case 100.

[0067] The protective sheet 340 may be attached to the surface of the module frame 320 using an adhesive or glue. However, if the pressure of the gas g is so large that it exceeds the adhesive force, the protective sheet 340 may peel off from the module frame 320. That is, when the pressure of the gas g is high, the protective sheet 340 may peel off from the surface of the module frame 320 and may not function to filter spark particles and flames.

[0068] The battery pack of the present invention is characterized by the addition of a structure that can push the protection sheet 340 toward the module frame 320 to prevent the protection sheet 340 from being removed from the surface of the module frame 320 as described above.

[0069] Specifically, the upper case 200 includes an elastic member 210 at its lower end for applying pressure to the upper portion of the cell assembly 300 seated in the pack case 100 .

[0070] FIG. 8 is a bottom perspective view of upper case 200.

[0071] Referring to FIG. 8, a plurality of elastic members 210 are formed on the lower end of the upper case 200. As shown in FIG.

[0072] Each elastic member 210 may be, for example, a spring or a foam member having elastic restoring force, and is disposed to transmit an elastic force downward based on the upper case 200 .

[0073] 9 shows the battery pack of FIG. 5 with the upper case 200 shown with hidden lines so that the elastic member 210 can be seen.

[0074] The elastic members 210 are formed at positions corresponding to the cell assemblies 300 .

[0075] The elastic member 210 is naturally pressed by the upper end of the cell assembly 300 as the upper case 200 and the pack case 100 are combined. That is, the elastic member 210 is pressed by the upper end of the cell assembly 300, and simultaneously transmits an elastic force to the upper part of the cell assembly 300, thereby conversely applying pressure to the protection sheet 340 attached to the upper part of the cell assembly 300.

[0076] It is preferable that the elastic member 210 is extended to an extent that it can apply pressure to the upper portion of each cell assembly 300 when the upper case 200 is completely coupled to the pack case 100. Therefore, the protective sheet 340 attached to the module frame 320 of the cell assembly 300 can be pressed by the lower end of the elastic member 210 and maintained in an attached state.

[0077] However, the opening hole 321 of the cell assembly 300 must not be completely blocked by the elastic member 210 .

[0078] FIG. 10 shows the state in which the upper case 200 and pack case 100 shown in FIG. 9 are joined together.

[0079] If the elastic member 210 blocks the opening hole 321, gas g inside the cell assembly 300 may not be smoothly discharged in the event of thermal runaway of the cell, which may result in an explosion. Also, the elastic member 210 may pass through the opening hole 321 and directly contact the internal cell stack 310, causing damage.

[0080] As shown in FIG. 10, the elastic member 210 is formed at the lower end of the upper case 200 so as to be offset from the opening hole 321 of the cell assembly 300 .

[0081] FIG. 11 is a simplified cross-sectional view of a battery pack in which one of the cell assemblies 300 is mounted.

[0082] Referring to FIG. 11, the elastic members 210 formed at the lower end of the upper case 200 press the module frame 320 in the cell assembly 300 where the opening hole 321 is not located.

[0083] FIG. 12 shows the movement of gas g generated in the cell stack 310 when thermal runaway occurs in the battery pack of FIG.

[0084] 12, gas g rising upward from cell stack 310 passes through opening holes 321 and protective sheet 340 and moves between upper case 200 and cell assembly 300. That is, gas g moves between a plurality of elastic members 210 interposed between upper case 200 and cell assembly 300 and then can be discharged to the outside.

[0085] The battery pack of the present invention further includes a vent hole (not shown) formed to communicate with the internal space so that gas g generated inside can be vented to the outside.

[0086] Therefore, in the battery pack of the present invention, the high-temperature gas g discharged through the opening hole 321 of the cell assembly 300 can be discharged to the outside through the discharge hole.

[0087] The discharge hole may be formed on one side of the side beam 120 of the pack case 100 or on one side of the upper case 200 .

[0088] (Second embodiment) The opening hole 321 of the cell assembly 300 accommodated in the battery pack of the present invention may have a slit shape, that is, the opening hole 321 may be elongated in one direction.

[0089] FIG. 13 shows a battery pack according to a second embodiment of the present invention, FIG. 14 shows a cell assembly 300 housed in FIG. 13, and FIG. 15 shows the cell assembly 300 of FIG. 14 with the protective sheet 340 separated.

[0090] 13 to 15, the opening hole 321 is formed to extend along the longitudinal direction d4 of the cell assembly 300.

[0091] The opening hole 321 may have a shape extending along the width direction d3 of the cell assembly 300 in addition to the shape shown in the drawings.

[0092] The present invention has been described in more detail above through the drawings and embodiments, etc. However, the configurations shown in the drawings or embodiments in this specification are merely one embodiment of the present invention and do not represent all of the technical ideas of the present invention, and therefore, there may be various equivalents and modifications that can replace them at the time of filing this application. [Explanation of symbols]

[0093] 10: (Conventional technology) Pack case 20: (Prior Art) Cell Assembly 21: (Prior Art) End Plate 22: (Prior art) Module frame 23: (Prior Art) Opening Hole 24: (Prior Art) Cell 25: (Conventional technology) Cell stack 26: (Prior Art) Electrode Lead 100: Pack case 110: Base plate 120: Side beam 130: Cross beam 200: Upper case 210: Elastic member 300: Cell assembly 310: Cell stack 320:Module Frame 321: Opening hole 330: End plate 340: Protective sheet g: gas d1: Width direction of the battery pack d2: Longitudinal direction of the battery pack d3: Width direction of cell assembly d4: longitudinal direction of cell assembly

Claims

1. A battery pack containing the cell assembly, a pack case in which the cell assembly is seated; an upper case coupled to the pack case to cover an upper portion of the cell assembly seated inside the pack case; Including, The upper case includes an elastic member at a lower end thereof for applying pressure to an upper portion of the cell assembly seated in the pack case.

2. The cell assembly includes: a cell stack including a plurality of cells; a module frame surrounding at least one side of the cell stack; 10. The battery pack of claim 1, comprising:

3. The battery pack according to claim 2 , wherein the module frame includes an opening hole that exposes the cell stack therein to the outside.

4. The battery pack of claim 3 , wherein the opening hole is formed in one of a circular shape and a polygonal shape.

5. The battery pack according to claim 3 , wherein the opening hole is formed to extend along one of a lengthwise direction and a widthwise direction of the cell assembly.

6. The cell assembly includes: The battery pack of claim 3 , further comprising a protection sheet attached to a surface of the module frame to cover the opening hole.

7. The battery pack of claim 3 , wherein the elastic member of the upper case is formed at a position where the opening hole of the cell assembly is not provided.

8. The battery pack according to claim 6 , wherein the opening hole is formed on the module frame located above the cell assembly.

9. The battery pack according to claim 6 , wherein the protective sheet has a porous structure including a plurality of voids that selectively allow gas to pass through.

10. The battery pack according to claim 6 , wherein the protective sheet has a structure in which no voids are formed so that gas cannot pass through.

11. The battery pack according to claim 6 , wherein the protective sheet has electrical insulation properties.

12. The battery pack according to claim 6 , wherein the protective sheet has heat resistance and flame retardancy.

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