Insulation pad for secondary battery and battery module including same

Abstract

The present invention relates to an insulation pad for a secondary battery and a battery module including same, the insulation pad comprising a support member and a foam layer formed on one surface of the support member, wherein the foam layer includes an edge part and a central part located inside the edge part, and the porosity of the edge part is smaller than the porosity of the central part. The edge part is reduced in porosity through thermocompression, and the pores in the edge part may be filled with a filler for preventing the penetration of moisture and gas.

Description

Insulating pad for secondary battery and battery module including same

[0001] This application claims the benefit of priority to Korean Patent Application No. 2024-0109392, filed August 14, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an insulating pad for a secondary battery and a battery module including the same. Specifically, the present invention relates to an insulating pad for a secondary battery capable of suppressing heat transmission between a plurality of closely arranged battery cells and enhancing insulation performance, and a battery module including the same.

[0003]

[0004] Rechargeable lithium secondary batteries are widely used as energy sources for wireless mobile devices and wearable devices, and are also used as energy sources for electric vehicles and hybrid electric vehicles, which are presented as alternatives to existing gasoline and diesel vehicles that cause air pollution.

[0005] The above lithium secondary battery can be divided into a square battery cell including a metal can-shaped case, a cylindrical battery cell, and a pouch-shaped battery cell including a case formed from a laminate sheet. Among these, pouch-shaped battery cells are widely used due to their advantages of being easy to change shape and being able to increase energy density during storage and lamination.

[0006] In general, lithium secondary batteries can experience volume expansion of battery cells during repeated charging and discharging processes. When a battery module is manufactured by stacking multiple pouch-type battery cells in close contact, the expansion pressure of the battery cells contained within the battery module case can damage the battery cells or deform the battery module.

[0007] Accordingly, by interposing an elastic insulating pad between pouch-type battery cells to accommodate the volume of the expanded battery cells, the pressure difference between the battery cells can be reduced and a constant surface pressure can be maintained.

[0008] Fig. 1 is a perspective view of a conventional insulation pad. Referring to Fig. 1, the insulation pad is configured such that a foam layer (20) is arranged on one side of a support member (10), and insulation pads having such a structure can be alternately stacked with pouch-type battery cells (not shown) to form a battery cell stack.

[0009] Meanwhile, if ignition occurs in any one of the multiple battery cells constituting the battery cell stack, high-temperature gas, thermal energy, and flames may be transmitted to adjacent battery cells through the foam layer (20) of the insulating pad. This thermal propagation phenomenon may be continuously transmitted to adjacent battery cells, and thus, the thermal runaway phenomenon may continue until the entire battery module is completely burned, which may lead to a large fire.

[0010] Patent Document 1 discloses a high-voltage battery module in which a heat shield is disposed within a module case, wherein the heat shield is disposed between cells within the module case or between cells and the module case, and includes a first reaction pad and a second reaction pad positioned outside the edge of the first reaction pad, wherein the first reaction pad and the second reaction pad are made of materials having different compressibility.

[0011] Patent Document 1 has the effect of delaying heat transmission between cells when a thermal runaway situation occurs in a battery cell by providing a heat shield inside a battery module. However, since the heat shield of Patent Document 1 includes two types of reaction pads made of different materials, the manufacturing cost increases and the manufacturing process becomes complicated.

[0012] Patent Document 2 relates to a secondary battery charging / discharging system. Multiple battery cells are arranged within a tray, with an insulating pad positioned between the outermost cell and the tray, thereby minimizing temperature variations between the cells during the charging / discharging process. However, Patent Document 2 does not present a technology for preventing high-temperature gases or flames resulting from a battery cell ignition from spreading to other cells.

[0013] Therefore, there is a need for a technology for an insulating pad that can be interposed between battery cells to maintain a constant surface pressure applied to the battery cells, and can prevent high-temperature gases, heat energy, and flames generated when a battery cell ignites from spreading to adjacent battery cells through simple structural modification.

[0014] (Patent Document 1) Korean Patent Publication No. 2023-0025973 (February 24, 2023)

[0015] (Patent Document 2) Korean Patent Publication No. 2022-0108972 (August 4, 2022)

[0016]

[0017] The present invention is intended to solve the above-mentioned problem, and provides an insulating pad for a secondary battery capable of blocking the transmission of high-temperature gas, heat energy, and flame between battery cells in a battery cell stack in which a plurality of pouch-type battery cells are stacked, and securing insulating performance, and a battery module including the same.

[0018]

[0019] In order to achieve this purpose, an insulating pad for a secondary battery according to the present invention includes a support member (100) and a foam layer (200) formed on one surface of the support member (100), and the foam layer (200) includes an edge portion (210) and a center portion (220) located inside the edge portion (210), and the pores of the edge portion (210) may be smaller than the pores of the center portion (220).

[0020] In addition, in the insulating pad for a secondary battery according to the present invention, the edge portion (210) may have a pore size that does not allow gas and liquid to pass through.

[0021] In addition, in the insulating pad for a secondary battery according to the present invention, the edge portion (210) may be formed in a form without pores by melting the foam layer.

[0022] In addition, in the insulating pad for a secondary battery according to the present invention, the edge portion (210) may be in a state of being thermally compressed in the thickness direction.

[0023] In addition, in the insulating pad for a secondary battery according to the present invention, the thickness of the edge portion (210) may be 80% or less of the thickness of the center portion (220).

[0024] In addition, in the insulating pad for a secondary battery according to the present invention, the edge portion (210) may be in a form in which a filler is filled within the pores.

[0025] In addition, in the insulating pad for a secondary battery according to the present invention, the filler may be at least one selected from the group consisting of polyethylene, ethylene-propylene rubber, polyethylene naphthalate, polyethylene terephthalate, and combinations thereof.

[0026] In addition, in the insulating pad for a secondary battery according to the present invention, the viscosity of the filler may be 20,000 cP to 80,000 cP.

[0027] In addition, in the insulating pad for a secondary battery according to the present invention, the edge portion (210) and the center portion (220) may be made of the same material.

[0028] In addition, in the insulating pad for a secondary battery according to the present invention, the edge portion (210) and the center portion (220) may include at least one selected from the group consisting of polyurethane, silicone, aerogel, polyurethane and mica composite, silicone and mica composite, and aerogel and mica composite.

[0029] In addition, in the insulating pad for a secondary battery according to the present invention, the support member (100) may be an impermeable film through which gas and liquid cannot pass.

[0030] The present invention provides a battery module including the insulating pad, wherein the battery module may include a plurality of pouch-shaped battery cells stacked in a vertical or horizontal direction in parallel, and an insulating pad disposed between the plurality of battery cells.

[0031]

[0032] The present invention can also be provided in a form in which various means for solving the above problem are combined.

[0033]

[0034] As described above, the secondary battery insulating pad according to the present invention has an edge portion of the foam layer having a pore size that does not allow gas and liquid to pass through or a form without pores, so gas and liquid cannot pass through the outer periphery of the insulating pad, which can block heat transfer between battery cells, thereby having the advantage of improving the safety of the battery module.

[0035] In addition, the insulating pad for a secondary battery according to the present invention has the advantage of a simple manufacturing process for the insulating pad for a secondary battery, as the edge of the foam layer can be transformed into a form having a pore size that does not allow gas and liquid to pass through or a form without pores through a process of thermo-compressing the edge or filling the filler.

[0036]

[0037] Figure 1 is a perspective view of a conventional insulation pad.

[0038] Figure 2 is a perspective view of an insulating pad for a secondary battery according to the first embodiment of the present invention.

[0039] Figure 3 is a cross-sectional view taken along line A-A' of Figure 2.

[0040] Figure 4 is a perspective view of an insulating pad for a secondary battery according to a second embodiment of the present invention.

[0041] Figure 5 is a cross-sectional view taken along line B-B' of Figure 4.

[0042] FIG. 6 is a cross-sectional view of a battery module equipped with an insulating pad for a secondary battery according to the first embodiment of the present invention.

[0043]

[0044] Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail, so that those skilled in the art can easily implement the present invention. When describing the operating principles of the embodiments of the present invention in detail, detailed descriptions of known functions or components will be omitted if they are deemed to unnecessarily obscure the gist of the present invention.

[0045] Parts with similar functions and actions are designated by the same drawing reference numerals throughout the drawings. Throughout the specification, when a part is said to be connected to another part, this includes not only direct connections but also indirect connections with other elements intervening. Furthermore, inclusion of a component does not exclude other components unless otherwise specifically stated, but rather implies the inclusion of additional components.

[0046] The description that concretizes or adds to the components may be applied to all inventions unless there is a special limitation, and is not limited to the description of a specific invention.

[0047] Throughout the description and claims of the invention herein, the singular includes the plural unless otherwise stated.

[0048] Throughout the description and claims of the present invention, the term "or" includes "and" unless otherwise stated. Therefore, "comprising A or B" means all three cases of including A, including B, or including A and B.

[0049] The present invention is described in detail with examples according to the drawings.

[0050] The insulating pad for a secondary battery according to the present invention is configured such that a support member and a foam layer are laminated to form an adhesive surface on opposite surfaces that come into contact with each other. Typically, the foam layer has a porous structure, allowing gas and liquid to move through the pores. However, the insulating pad for a secondary battery according to the present invention is configured such that gas and liquid are prevented from escaping through the outer periphery of the foam layer.

[0051] For example, when pouch-type battery cells and insulating pads are alternately arranged to form a battery cell stack, the pouch-type battery cells expand in volume during the charge / discharge process and thus come into close contact with the insulating pads, so that heat energy and gas transfer may be blocked in the direction in which the insulating pads face the pouch-type battery cells. However, since the thickness-wise side of the insulating pads does not face the pouch-type battery cells, inflow and outflow of external and internal substances may be possible, but the present invention can prevent heat transfer through the thickness-wise side of the insulating pads.

[0052] FIG. 2 is a perspective view of an insulating pad for a secondary battery according to a first embodiment of the present invention, and FIG. 3 is a cross-sectional view taken along line A-A' of FIG. 2.

[0053] Referring to FIGS. 2 and 3, the insulating pad (300) for a secondary battery according to the first embodiment is configured to include a support member (100) and a foam layer (200) formed on one surface of the support member (100).

[0054] First, the support member (100) may be a base material for forming a foam layer (200), and in order to increase the insulation performance of the insulation pad (300), it is desirable that gas and liquid introduced into the foam layer (200) not pass through the support member (100), and thus the support member (100) may be composed of an impermeable film that does not allow gas and liquid to pass through.

[0055] Here, the non-permeable film may include, for example, polyurethane, polyester, polyethylene, or polypropylene, and may be composed of a single layer including these, or a multilayer structure including two or more layers.

[0056] The foam layer (200) includes an edge portion (210) and a center portion (220) located inside the edge portion (210). At this time, the pore size of the edge portion (210) is preferably smaller than the pore size of the center portion (220), and it is more preferable to have a pore size that does not allow gas and liquid to pass through, and it is most preferable to have a pore-free form.

[0057] In detail, since it is desirable to configure the edge portion (210) so that gas and liquid cannot pass through, the edge portion (210) may be provided in a form in which the pores are small enough to prevent gas and liquid from passing through or in which there are no pores at all.

[0058] As described above, the thickness of the edge portion (210) is thinner than that of the center portion (220) so that the pore size of the edge portion (210) can be reduced or the shape can be made to have no pores at all. This can be achieved, for example, by thermo-compressing the edge portion (210) in the thickness direction.

[0059] That is, before thermal compression, the edge portion (210) and the center portion (220) are made of the same material and have the same thickness. Of course, the second pores (221) inside the edge portion (210) and the center portion (220) also have a uniform size.

[0060] However, as in the direction of the arrow in Fig. 3, if only the edge portion (210) is thermally compressed in the thickness direction (D), the thickness of the edge portion (210) becomes thinner, and as a result, the pore size of the edge portion (210) is reduced or the shape becomes one in which there are no pores at all.

[0061] Here, the compression ratio of the edge portion (210) by thermal compression may vary depending on the material and porosity of the foam layer (200), but the thickness (D1) of the edge portion (210) may be 80% or less of the thickness (D2) of the center portion (220), specifically 50% or less, and more specifically 30% or less.

[0062] In addition, the edge portion (210) is in a heat-compressed state at a temperature higher than the melting point of the foam layer (200), so the edge portion (210) does not expand again and maintains the heat-compressed state.

[0063] As described above, the edge portion (210) and the center portion (220) are made of the same material, for example, the edge portion (210) and the center portion (220) may include at least one selected from the group consisting of polyurethane, silicone, aerogel, polyurethane and mica composite, silicone and mica composite, and aerogel and mica composite.

[0064] In this way, the insulating pad for a secondary battery according to the first embodiment is formed in a form in which the outer periphery of the edge portion (210) is thermally compressed to make the thickness thinner and the pores become smaller or disappear, so that gas and liquid cannot move through the edge portion (210).

[0065] Of course, in the insulating pad for a secondary battery according to the first embodiment, the first pore (221) of the center (220) can be easily filled with air having a high specific heat, and when filled, it cannot be discharged to the outside but remains within the pore, so that the insulating performance can be improved by blocking the flow of air. A detailed explanation regarding this will be provided later.

[0066]

[0067] FIG. 4 is a perspective view of an insulating pad for a secondary battery according to a second embodiment of the present invention, and FIG. 5 is a cross-sectional view taken along line B-B' of FIG. 4.

[0068] Referring to FIGS. 4 and 5, the insulating pad (300) for a secondary battery according to the second embodiment has an edge portion (210) that is not thermally compressed, and the thickness of the edge portion (210) and the thickness of the center portion (220) are substantially the same.

[0069] The insulating pad for a secondary battery according to the second embodiment is in a form in which a filler (212) is filled in the first pore (211) in the edge portion (210). For example, the first pore (211) located near the surface of the edge portion (210) is filled with the filler (212), or most of the inside of the first pore (211) in the edge portion (210) is filled with the filler (212), or the entire first pore (211) in the edge portion (210) is filled with the filler (212), so that gas and liquid cannot move through the edge portion (210).

[0070] Here, since the filler (212) must be stably supported and fixed by being filled in the first pore (211) of the edge portion (210), a high viscosity material can be used. The viscosity of the filler (212) may be affected by the pore size of the foam layer (200), but for example, the viscosity of the filler (212) may be 20,000 cP to 80,000 cP, and specifically, 40,000 cP to 80,000 cP.

[0071] If the viscosity of the filler is less than 20,000 cP, it may not be stably contained in the first pore (211), and if it exceeds 80,000 cP, it may not be easy to fill in the first pore (211), so the viscosity of the filler is preferably within the above-mentioned range.

[0072] Meanwhile, as the filler having the aforementioned high viscosity, a paste in which an inorganic filler is dispersed together with a thickener can be used, and at this time, the inorganic filler can be one or more selected from the group consisting of SiO2, SiN4, ZrP, Al2O3, TiO2, ZnO, MgO, and BaTiO3.

[0073] Additionally, a polymer resin may be used as a filler, and the polymer resin may be at least one selected from the group consisting of polyethylene, ethylene-propylene rubber, polyethylene naphthalate, polyethylene terephthalate, and combinations thereof.

[0074]

[0075] FIG. 6 is a cross-sectional view of a battery module equipped with an insulating pad for a secondary battery according to the first embodiment of the present invention.

[0076] Referring to FIGS. 2, 3 and 6 together, a battery module according to the present invention is formed by stacking a plurality of pouch-shaped battery cells (1) in a state of being placed side by side on the bottom of a module case (30).

[0077] In addition, an insulating pad (300) is interposed between the pouch-type battery cells (1) and between the module case (30) and the pouch-type battery cells (1). Here, the insulating pad (300) may be configured to have a size corresponding to the area of ​​the rectangular side excluding the sealing portion of the pouch-type battery cells (1).

[0078] The insulating pad (300) functions as a spacer during the initial charging and discharging of the battery module, and when the volume of the pouch-type battery cell (1) expands and pressure is applied to the insulating pad (300), the insulating pad absorbs the pressure and can improve the pressure deviation applied to the pouch-type battery cell (1).

[0079] In addition, the insulation pad (300) prevents heat from spreading in the thickness direction (x) side, i.e., to the pouch-shaped battery cells (1) located nearby. Specifically, even if any one of the plurality of pouch-shaped battery cells (1) ignites and releases high-temperature gas, high heat energy, and flames, heat spreading in the thickness direction (x) of the insulation pad can be prevented.

[0080] The pouch-shaped battery cells (1) and the insulating pad are arranged in close contact, and the edge portion (210) of the insulating pad has a structure in which gas and liquid cannot move, so that the air filled in the second pore (221) in the center portion (220) of the insulating pad can remain as is without being released.

[0081] Therefore, when the insulation pad (300) of the present invention is used, heat transmission between pouch-type battery cells (1) can be delayed or prevented, and as a result, the safety of the battery module can be contributed.

[0082] Although the battery module equipped with an insulating pad according to Example 1 has been described, even if a different insulating pad is equipped in Example 2, the same effect can be expected because heat propagation does not occur in the thickness direction of the insulating pad.

[0083]

[0084] Anyone with ordinary knowledge in the field to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

[0085] (Explanation of symbols)

[0086] 1: Pouch-type battery cell

[0087] 10, 100: Absence of support

[0088] 20, 200: Foam layer

[0089] 30: Module Case

[0090] 210: Edge

[0091] 211: First pore 212: Filler

[0092] 220: Center 221: Second pore

[0093] 300: Insulating pad

Claims

1. Supporting member; and Including a foam layer formed on one surface of the above support member; The above foam layer includes an edge portion and a center portion located inside the edge portion, An insulating pad for a secondary battery, characterized in that the pores at the edge are smaller than the pores at the center.

2. In paragraph 1, An insulating pad for a secondary battery, characterized in that the edge portion has a pore size that does not allow gas and liquid to pass through.

3. In paragraph 2, An insulating pad for a secondary battery, characterized in that the edge portion is formed by melting the foam layer and having no pores.

4. In paragraph 2, An insulating pad for a secondary battery, characterized in that the edge portion is in a state of being thermally compressed in the thickness direction.

5. In paragraph 4, An insulating pad for a secondary battery, characterized in that the thickness of the edge portion is 80% or less of the thickness of the center portion.

6. In paragraph 2, An insulating pad for a secondary battery, characterized in that the edge portion is in a form in which a filler is filled within the pores.

7. In paragraph 6, An insulating pad for a secondary battery, characterized in that the filler is at least one selected from the group consisting of polyethylene, ethylene-propylene rubber, polyethylene naphthalate, polyethylene terephthalate, and combinations thereof.

8. In paragraph 6, An insulating pad for a secondary battery, characterized in that the viscosity of the filler is 20,000 cP to 80,000 cP.

9. In paragraph 2, An insulating pad for a secondary battery, characterized in that the edge portion and the center portion are made of the same material.

10. In paragraph 9, An insulating pad for a secondary battery, characterized in that the edge portion and the center portion include at least one selected from the group consisting of polyurethane, silicone, aerogel, polyurethane and mica composite, silicone and mica composite, and aerogel and mica composite.

11. In paragraph 10, An insulating pad for a secondary battery, characterized in that the above-mentioned support member is an impermeable film that does not allow gas and liquid to pass through.

12. In a battery module including an insulating pad according to any one of claims 1 to 11, A plurality of pouch-shaped battery cells stacked in a vertical or horizontal direction; and A battery module characterized by including an insulating pad disposed between the plurality of battery cells.

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