Cell pad for secondary battery and manufacturing method therefor

Abstract

The present invention relates to a cell pad for a secondary battery and a manufacturing method therefor. Specifically, the present invention relates to a cell pad for a secondary battery and a manufacturing method therefor, wherein the cell pad is installed between secondary-battery cells to prevent thermal runaway occurring in one cell from propagating to another cell.

Description

Cell pad for secondary battery and manufacturing method thereof

[0001] The present invention relates to a cell pad for a secondary battery and a method for manufacturing the same. Specifically, the present invention relates to a cell pad for a secondary battery installed between secondary battery cells to prevent a thermal runaway phenomenon occurring in one cell from spreading to another cell, and a method for manufacturing the same.

[0002] Generally, secondary batteries for electric vehicles can be divided into three types based on the shape of their packaging materials: cylindrical secondary batteries, in which the electrode assembly is housed in a metal can; pouch-type secondary batteries, in which the electrode assembly is housed in a pouch-shaped packaging material; and secondary batteries, in which the battery material is packaged in a square aluminum can case.

[0003] Since the battery cells are tightly stacked in multiples (12 cells), there was a problem that if a thermal runaway phenomenon occurred in some battery cells, the thermal runaway phenomenon could spread to adjacent battery cells in a short period of time, leading to disasters such as fire or explosion of the battery module or battery pack, which are battery units with a larger capacity than the battery cells.

[0004] In particular, when a thermal runaway phenomenon occurs, the battery cell generates an ultra-high temperature region of approximately 600℃ to 900℃, so due to such high temperature, surrounding combustible materials (SEI, solid electrolyte interphase) decomposition → negative electrode electrolyte → positive electrode decomposition → short circuit → electrolyte ignition → thermal runaway) are ignited, further increasing the risk of fire. In addition, if a thermal runaway phenomenon occurs in one of the battery cells due to a manufacturing defect or misuse of the battery pack, the thermal runaway phenomenon may be transmitted to adjacent cells.

[0005] Conventionally used battery packs for electric vehicles are configured to prevent thermal runaway phenomenon occurring in a single-axis battery cell from spreading to another battery cell by installing a buffer pad made of urethane foam (PU foam) or silicone foam between a single-axis battery cell and another adjacent battery cell, i.e., to delay and prevent thermal runaway phenomenon from spreading.

[0006] However, although urethane foam and silicone foam have a cushioning function that can be expanded according to pressure (surface pressure), they have a problem in that they lose their viscoelastic function at high temperatures (200°C). In particular, since the foam decomposes in a temperature range (around 200°C) lower than the high temperature range where the battery's thermal runaway phenomenon occurs, there is a problem in that the desired thermal runaway delay effect cannot be expected.

[0007] To address these issues, Korean Patent Publication No. 10-2023-0132800, "Insulating Multilayer Sheet, Manufacturing Method Thereof, and Articles Using the Same," proposes a multilayer sheet structure supplemented with silicone paper, glass fiber, and other materials. However, it lacks cost-effectiveness and functions as a buffer pad and thermal runaway prevention pad.

[0008] In addition, Korean Patent Publication No. 10-2022-0013603 discloses a "thermal runaway prevention pad and a battery cell storage structure including the same," wherein the thermal runaway prevention pad includes a first buffer member made of an elastic material, a fire extinguishing member from which a fire extinguishing agent is ejected, and a second buffer member. Furthermore, related technologies are disclosed in Korean Patent No. 10-2425374, Korean Patent Publication No. 10-2023-0132800, Korean Patent No. 10-2669747, and U.S. Patent Publication No. US2024 / 0145843.

[0009] The present invention aims to provide a cell pad for a secondary battery and a method for manufacturing the same, which can delay thermal runaway that may occur due to misuse or damage of an electric vehicle battery.

[0010] The above-described task is achieved by a cell pad for a secondary battery comprising a polymer foam, a carbon fiber composite attached to both sides of the polymer foam, and an adhesive layer between the polymer foam and the fiber composite layer.

[0011] Preferably, the carbon fiber composite can be manufactured by coating a semi-fireproof paste containing an expandable flame retardant composition on a carbon fiber nonwoven fabric.

[0012] Also preferably, the polymer foam can be manufactured by mixing an expandable flame retardant composition, fumed silica and a foaming agent into one type of rubber selected from the group consisting of silicone rubber, thermoplastic elastomer and EPDM rubber, and then compression molding the mixture.

[0013] Also preferably, the semi-fireproof paste may contain 80 to 150 parts by weight of an intumescent flame retardant composition, 40 to 60 parts by weight of aluminum hydroxide, 1 to 10 parts by weight of an aqueous montmorillonite solution, and 1 to 10 parts by weight of a polyoxy(propylene-ethylene) copolymer, per 100 parts by weight of a water-soluble epoxy resin or vinyl acetate ethylene copolymer.

[0014] Also preferably, the inflatable flame retardant composition may contain 20 to 40 parts by weight of melamine, 20 to 40 parts by weight of carbonyl diamide (urea), and 30 to 50 parts by weight of D-glucitol per 100 parts by weight of ammonium polyphosphate.

[0015] Also preferably, the adhesive layer may include an epoxy-based oil-based flame-retardant adhesive or an epoxy-based water-based flame-retardant adhesive.

[0016] Also preferably, the carbon fiber nonwoven fabric may be treated with a sizing agent including liquid epoxy resin and hydrophilic fumed silica.

[0017] In addition, the above-described task is achieved by a method for manufacturing a cell pad for a secondary battery, comprising the steps of: treating a carbon fiber nonwoven fabric with a sizing agent; coating a semi-fireproof paste containing an expandable flame retardant composition on the sizing-treated carbon fiber nonwoven fabric, drying, and curing to produce a carbon fiber composite; mixing one type of rubber selected from the group consisting of silicone rubber, thermoplastic elastomer, and EPDM rubber, an expandable flame retardant composition, fumed silica, and a blowing agent, and then compression molding to produce a polymer foam; applying an epoxy adhesive to both surfaces of the polymer foam, and attaching the carbon fiber composite to both surfaces of the polymer foam; and heat-treating the attached polymer foam and the carbon fiber composite to dry and harden them.

[0018] The cell pad for secondary batteries according to the present invention has quasi-fireproof performance and thermal insulation performance, and thus maintains its shape even at thermal runaway temperatures, thereby preventing and delaying thermal runaway. Furthermore, due to its excellent quasi-fireproof performance and thermal insulation performance, the cell pad for secondary batteries according to the present invention can be used as a fire-prevention product, such as a fire tent or fire curtain, or as a fire-prevention structural material for the exterior walls of buildings.

[0019] Figure 1 is a perspective view showing the structure of a cell pad for a secondary battery according to the present invention.

[0020] Figure 2 is a schematic diagram showing a configuration in which a cell pad for a secondary battery according to the present invention is positioned between cells in a battery pack.

[0021] Figure 3 illustrates the results of a combustion performance test of a cell pad for a secondary battery according to the present invention.

[0022] Unless otherwise defined, all technical terms used in this invention have the following definitions and correspond to the meanings commonly understood by those skilled in the art in the relevant fields of the present invention. Furthermore, while preferred methods and samples are described herein, similar or equivalent methods are also included within the scope of the present invention.

[0023] The term "about" means an amount, level, value, number, frequency, percentage, dimension, size, amount, weight, or length that varies by 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% of the reference amount, level, value, number, frequency, percentage, dimension, size, amount, weight, or length.

[0024] Throughout this specification, unless the context otherwise requires, the words "comprise" and "comprising" are to be understood to imply the inclusion of a stated step or component, or group of steps or components, but not the exclusion of any other step or component, or group of steps or components.

[0025]

[0026] Fig. 1 shows the structure of a cell pad according to the present invention. Referring to Fig. 1, the cell pad for a secondary battery according to the present invention includes a polymer foam (11), a carbon fiber composite (12) attached to both sides of the polymer foam, and an adhesive layer (not shown) between the polymer foam and the carbon fiber composite layer.

[0027] The above polymer foam (11) can be manufactured by mixing an expanded flame retardant composition, a foaming agent, and fumed silica with one type of rubber selected from the group consisting of silicone rubber, thermoplastic elastomer, and EPDM rubber, and then compression molding. Preferably, per 100 parts by weight of one type selected from the group consisting of silicone rubber, thermoplastic elastomer, and EPDM rubber, it can contain 100 parts by weight of a flame retardant (FR-IFC, expanded flame retardant composition), 40 to 60 parts by weight of fumed silica, and 1 to 10 parts by weight of a foaming agent, a dispersing agent, a crosslinking agent, etc., as additives.

[0028] Polymer foam can be made of various types of rubber, thermoplastic elastomer, polyolefin polymer, etc., but preferably, it can be made of one type of rubber selected from the group consisting of silicone rubber, thermoplastic elastomer, and EPDM rubber. Specifically, considering the temperature dependence of compression set performance (creep, stress relaxation), which is one of the key specifications of cell pad, silicone rubber, which has the best heat resistance among rubbers, can be used.

[0029] The above polymer foam can be manufactured by mixing a mixture (compound) of one type of rubber selected from the group consisting of silicone rubber, thermoplastic elastomer, and EPDM rubber with an expandable flame retardant composition, fumed silica, and a foaming agent, and manufacturing the mixture by compression molding or continuous foaming.

[0030] The above compression molding method involves mounting the mixture (compound) in a mold, applying a certain temperature, pressure, and time using a compression press, and compressing and then releasing the pressure to create a foam. This is called a compression molded foam. According to one embodiment of the present invention, the rubber can be manufactured by mixing an expanded flame retardant composition (FR-IFC), fumed silica, and a blowing agent, and then applying a peroxide crosslinking system, through a compression molding method.

[0031] The above continuous foaming method is a continuous process in which the mixture (compound) is supplied to an extruder, extruded from an extruder die to produce an extruded sheet, and foam is formed by passing the sheet through a HAV (hot air vulcanization, curing tunnel).

[0032] The above carbon fiber composite (12) can be manufactured by coating a semi-fireproof paste containing an expandable flame retardant composition on a carbon fiber nonwoven fabric. The carbon fiber nonwoven fabric is not particularly limited, but may be a regenerated carbon fiber nonwoven fabric.

[0033] According to an embodiment of the present invention, the carbon fiber nonwoven fabric may be treated with a sizing agent prior to the coating step. The sizing agent includes a liquid epoxy resin and hydrophilic fumed silica. The liquid epoxy resin is not particularly limited, and any known product may be used. The sizing agent may be coated on the surface of the carbon fiber nonwoven fabric using a spray method, a knife coating method, or a slot die coating method, and then dried and cured. By treating the sizing agent, the adhesion with the semi-fireproof paste can be improved.

[0034] The above semi-combustible paste coating step can be performed as a continuous process or a discontinuous process.

[0035] For a continuous process, a semi-combustible paste can be applied to both sides of a sized carbon fiber nonwoven fabric using one of the following methods: roll coating, slot die coating, or knife coating, and then heat-treated to harden. Another method is to apply a semi-combustible paste onto the carbon fiber nonwoven fabric using a rotocure machine and heat-treat to harden it.

[0036] In the above curing step, a drying curing device can be used. For example, a drying device using air as a medium, such as a HACT (Hot air curing tunnel) or UHF-HACT (Ultra high frequency - hot air curing tunnel), can be used to cure the carbon fiber nonwoven fabric and the matrix resin, which is a semi-incombustible paste, to form a composite. The curing temperature is preferably 150°C to 200°C, and the curing time is 2 to 10 minutes. The curing time is a factor in determining the length of the drying curing device.

[0037] For discontinuous processes, it can be used in both mass and small-batch production.

[0038] Specifically, a semi-combustible paste is applied to a sized carbon fiber nonwoven fabric, dried, and then cut to the size of a cell pad using a die and dried and cured using a compression press. This process requires a preforming (die-cutting) machine and a mold for compression curing.

[0039] The above semi-fireproof paste may contain 80 to 150 parts by weight of an inflatable flame retardant composition (FR-IFC), 40 to 60 parts by weight of aluminum hydroxide, 1 to 10 parts by weight of an aqueous montmorillonite solution (G5 clay (MMT)-nanocomposite), and 1 to 10 parts by weight of a polyoxy(propylene-ethylene) copolymer, per 100 parts by weight of a water-soluble epoxy resin or vinyl acetate ethylene copolymer. The semi-fireproof paste can be manufactured using various types of mixers. Dissolvers, ribbon mixers, batch mixers, and planetary mixers can be used, and in-line mixers can also be used for mass production. Since the semi-fireproof paste has a medium viscosity of about 50,000 to 100,000 cps, it can be freely selected depending on the production volume. The above montmorillonite aqueous solution is a nanocomposite in which montmorillonite (MMT) is dispersed in an exfoliated form in deionized water. The exfoliated MMT nanocomposite exhibits excellent barrier properties and flame retardancy, and can provide a synergistic flame retardancy effect. When manufacturing a G5 clay nanocomposite, an inline mixer or an ultrasonic mixer can be used.

[0040] In addition, the intumescent flame retardant composition may contain 20 to 40 parts by weight of melamine, 20 to 40 parts by weight of carbonyldiamide (urea), and 30 to 50 parts by weight of D-glucitol per 100 parts by weight of ammonium polyphosphate. The intumescent flame retardant composition (FR-IFC) is an intumescent flame retardant system, and functions as an excellent flame retardant layer by forming a carbon barrier on the surface of a substrate to block the supply of oxygen and supply nitrogen.

[0041] The polymer foam and carbon fiber composite manufactured above can be interfacially bonded using an adhesive to manufacture a cell pad.

[0042] The above adhesive may be an epoxy-based oil-based flame-retardant adhesive or an epoxy-based water-based flame-retardant adhesive.

[0043] The above epoxy-based flame-retardant adhesive may include one or more epoxy resins, aluminum hydroxide, ammonium polyphosphate, melamine, dicyandiamide, and a latent curing agent. The epoxy resin may be a BGE modified epoxy resin, a CTBN modified epoxy resin, or a mixture thereof. The ammonium polyphosphate may be used for an intumescent barrier, and a latent curing agent (dicyandiamide) may be used to extend the pot life.

[0044] The above epoxy-based water-based flame-retardant adhesive contains a water-soluble epoxy resin and the above inflatable flame-retardant composition (FR-IFC) in equal weights, and may contain a latent curing agent (imidazole-based, EH5019S) and other additives. The above water-based flame-retardant adhesive may improve the flame retardancy of the cell pad by including the inflatable flame-retardant composition (FR-IFC).

[0045] The interfacially bonded cell pad can be heat-treated using a dry curing machine to ultimately manufacture a cell pad for a secondary battery. For example, dry curing can be performed using a HACT (Hot Air Curing Tunnel) or UHF-HACT (Ultra High Frequency - Hot Air Curing Tunnel), or continuous manufacturing can be performed using a Rotocure (American Biltrite Rubber) machine.

[0046] According to an embodiment of the present invention, the present invention provides a method for manufacturing a cell pad for a secondary battery, comprising the steps of: treating a carbon fiber nonwoven fabric with a sizing agent; coating a semi-fireproof paste containing an expandable flame retardant composition on the sizing-treated carbon fiber nonwoven fabric, drying, and curing to manufacture a carbon fiber composite; mixing one kind of rubber selected from the group consisting of silicone rubber, thermoplastic elastomer, and EPDM rubber with an expandable flame retardant composition, fumed silica, and a blowing agent to make a compound, and then compression-molding the compound to manufacture a polymer foam; applying an epoxy adhesive to both surfaces of the polymer foam and attaching the carbon fiber composite to both surfaces of the polymer foam; and heat-treating the attached polymer foam and the carbon fiber composite to dry and harden them.

[0047] The cell pad manufactured according to the present invention exhibits flame retardancy performance of a quasi-non-combustible grade that complies with KSFISO5660-1 (combustion performance test) and KSF2271 (gas toxicity test of building finishing materials).

[0048]

[0049] The present invention is described in detail with reference to the following examples, but the scope of the present invention is not limited by these examples.

[0050]

[0051] Example

[0052] A sizing agent having the composition shown in Table 1 below was prepared, sprayed on both sides of a regenerated carbon fiber nonwoven fabric, and then dried and cured. A semi-combustible paste coating solution was prepared with the composition shown in Table 3 below, applied on both sides of a sized carbon fiber nonwoven fabric, and heat-treated to produce a carbon fiber composite. An epoxy adhesive was prepared with the composition shown in Tables 7 and 8 below. The water-based epoxy adhesive shown in Table 8 was applied on both sides of a polymer foam prepared with the composition shown in Table 9, and the carbon fiber nonwoven fabric was interfacially bonded with the polymer foam, and dried and cured to produce a cell pad.

[0053] Classification Phr (weight fraction) Note KWER-40 100 bisphenol A type epoxy, Kumho P&B Chemical IL-silica 150 Refer to Table 2 Polyether modified siloxane 0.5 BYK 345 (trade name) Dyno S-360 0.5 Evonik Total 251

[0054] The above IL (ionic liquid) silica has the composition shown in Table 2 below.

[0055] Classification Phr (weight fraction) Note Aerosil 380-5100 Evonik (hydrophilic fumed silica) 1-ethyl-3-methylimidazolium dicyanamide 0.56 [EMIM] DCN Chloropropyl trimethoxysilane 1.355 CPTMS Total 101.915

[0056] The semi-combustible paste coating solution can be manufactured with the compositions shown in Tables 3 and 4 below. In this example, the composition shown in Table 4 was used.

[0057] Classification Phr (weight fraction) Note Vinylacetate ethylene copolymer 100 VAE emulsion G5 clay nanocomposite 5 See Table 5 Aminomethyl propanol (2-amino-2-methyl-1-propanol) 0.5 AMP-95 FR-IFC (intumescent flame retardant composition) 100 See Table 6 Aluminum hydroxide 50 Al (OH) ₃ Polyoxy (propylene-ethylene) copolymer 5 PE-62 (trade name) N (beta-aminoethyl) gamma-aminopropyltrimethoxy-silane 1.5 A-1120 (trade name) Calcium hydroxide 1 Al (OH) ₃ BYK 01 20.3 Compound of polyether withHydrophobic particleTotal281.8

[0058] ClassificationPhr (weight fraction)RemarksKEM128-70100bisphenol A type epoxy resin, Kukdo ChemicalG5 clay-nanocompoiste5Refer to Table 5Aminomethyl propanol(2-amino-2-methyl-1-propanol)0.5AMP-95FR-IFC(intumescent flame retardant composition)100Refer to Table 6Polyoxy(propylene-ethylene)copolymer5PE-62Aluminum hydroxide50Al(OH)₃Dicyandiamide7Latent curing agent, CAS No. 461-58-5Ajicure PN-232Curing agent, CAS No. 13491-76-2BYK0120.5Compound of polyether withHydrophobic particleN(beta-aminoethyl)gamma-aminopropyltrimethoxy-silane1A-1120Total230

[0059] The above G5 clay (MMT)-nanocomposite (C5-clay (MMT)-nanocompoiste) has the composition shown in Table 5 below.

[0060] Phr (weight fraction) Non-deionized water 100 DI-water MMT 5 Montmorillonite Polydiallyldimethylammonium chloride 1.65 FL 4540 (trade name) Total 106.65

[0061] The above intumescent flame-retardant composition (FR-IFC) has the composition shown in Table 6 below.

[0062] Classification Phr (weight fraction) Note Ammonium polyphosphate 100 APP Melamine 30 1,3,5-triazine 2,4,6-triamine Urea 30 Carbonyl diamide Sorbitol 40 D-glucitol Total 200

[0063] The composition of the flame-retardant adhesive is as shown in Table 7 below.

[0064] Classification Phr Weight fraction Remarks YD115J70 BGE modified epoxy resin KR20730 CTBN modified epoxy resin KBM6031 N-2-(aminoethyl)-3-aminopropyltrimethoxy silane Ammonium polyphosphate 20 APP Aluminum hydroxide 40 Al(OH)₃ Melamine 20 1,3,5-triazine 2,4,6-triamine Dicyandiamide 8 CAS No. 461-58-5 PN233 CAS No. 13491-76-2 BYK3551 polyacrylate BYK1611 Modified polyurethane Total 194

[0065] The composition of the water-based flame-retardant adhesive is as follows.

[0066] Classification Phr (weight fraction) Note KEM-128-70 100 Bisphenol A type epoxy resin, Kukdo Chemical G5 Clay-nanocomposite 5 Refer to Table 5 Aminomethyl propanol (2-amino-2-methyl-1-propanol) 0.5 AMP-95 FR-IFC 100 Refer to Table 6 Polyoxy (propylene-ethylene) copolymer 3 PE-62EH50 19 S20 Imidazole hardener, Adeka Korea N (beta-aminoethyl) gamma-aminopropyltrimethoxy-silane 1.5 A-1120 BYK0 1 20.5 Compound of polyether with hydrophobic particle Total 230.5

[0067] The composition of the polymer foam is as shown in Table 9 below. After mixing with the composition below, the polymer foam was manufactured by compression molding.

[0068] Classification Phr (weight fraction) Note Methyl vinyl silicone rubber 100 Shin etsu Japan Fumed silica 45 Aerosil-200 Dimethyl polysiloxane 10 Dispersant 1,1-azobis (1-acetoxy-1-phenylethane) 4 OT-OZA-15, azo blowing agent FR-IFC 100 Refer to Table 6 2,5-dimethyl-2,5-butylperoxy hexane 1.5 Trigonox 101 Total 286.5

[0069] Experimental example

[0070] After manufacturing three test specimens using the method described in the examples, combustion performance tests according to KSFISO5660-1 and gas toxicity tests for building finishing materials according to KSF2271 were conducted. The results are shown in Table 10 and Fig. 3.

[0071] Sample number Test body 1 Test body 2 Test body 3 Length (mm) 99.9799.9199.8799.9399.9799.99 Thickness (mm) 48.2349.2649.74 Mass before test (g) 64.4761.3062.41 Density (kg / m) 3 )133.8124.6125.6Total heat release (MJ / m) 2 )5.76.75.1 Maximum continuous heat release of 200 kW / m 2 Time exceeding (s)000Sample penetrationNoneNoneNoneIgnition time (s)01213Extinguishing time (s)02515Melting and shrinkage of specimen after test (mm)2.062.881.82THR(0-300) (MJ / m 2 )2.93.72.6THR(0-600) (MJ / m 2 )5.76.75.1 Test specimen height setting (mm)252525Other observationsDoes not ignite--

[0072] As shown in Table 10 and Figure 3, the cell pad according to the present invention satisfies the KSFISO5660-1 and KSF2271 test standards. This confirms that the cell pad has quasi-fireproof performance.

Claims

1. A cell pad for a secondary battery comprising a polymer foam, a carbon fiber composite attached to both sides of the polymer foam, and an adhesive layer between the polymer foam and the fiber composite layer.

2. A cell pad for a secondary battery, characterized in that in the first paragraph, the carbon fiber composite is manufactured by coating a semi-fireproof paste containing an expandable flame retardant composition on a carbon fiber nonwoven fabric.

3. A cell pad for a secondary battery, characterized in that in the first paragraph, the polymer foam is manufactured by mixing an expandable flame retardant composition, fumed silica, and a foaming agent into one type of rubber selected from the group consisting of silicone rubber, thermoplastic elastomer, and EPDM rubber, and then compression molding the mixture.

4. A secondary battery cell pad according to claim 2, characterized in that the semi-combustible paste comprises 80 to 150 parts by weight of an expandable flame retardant composition, 40 to 60 parts by weight of aluminum hydroxide, 1 to 10 parts by weight of an aqueous montmorillonite solution, and 1 to 10 parts by weight of a polyoxy(propylene-ethylene) copolymer per 100 parts by weight of a water-soluble epoxy resin or vinyl acetate ethylene copolymer.

5. A cell pad for a secondary battery, characterized in that the expanded flame retardant composition according to claim 2 or 3 comprises 20 to 40 parts by weight of melamine, 20 to 40 parts by weight of carbonyl diamide, and 30 to 50 parts by weight of D-glucitol per 100 parts by weight of ammonium polyphosphate.

6. A cell pad for a secondary battery, characterized in that in the first paragraph, the adhesive layer comprises an epoxy-based oil-based flame-retardant adhesive or an epoxy-based water-based flame-retardant adhesive.

7. A cell pad for a secondary battery, characterized in that in the second paragraph, the carbon fiber nonwoven fabric is treated with a sizing agent including liquid epoxy resin and hydrophilic fumed silica.

8. Step of applying a sizing agent to the carbon fiber nonwoven fabric; A step of manufacturing a carbon fiber composite by coating a semi-fireproof paste containing an expandable flame retardant composition on the above-mentioned sized carbon fiber nonwoven fabric, drying, and curing; A step of manufacturing a polymer foam by mixing one type of rubber selected from the group consisting of silicone rubber, thermoplastic elastomer, and EPDM rubber, an expandable flame retardant composition, fumed silica, and a foaming agent, and then compressing and molding the mixture; A step of applying an epoxy adhesive to both sides of the polymer foam and attaching the carbon fiber composite to both sides of the polymer foam; and A method for manufacturing a cell pad for a secondary battery, comprising a step of heat-treating and drying and curing the attached polymer foam and the carbon fiber composite.

9. A method for manufacturing a cell pad for a secondary battery, characterized in that in the 8th paragraph, the semi-combustible paste comprises 80 to 150 parts by weight of an expandable flame retardant composition, 40 to 60 parts by weight of aluminum hydroxide, 1 to 10 parts by weight of an aqueous montmorillonite solution, and 1 to 10 parts by weight of a polyoxy(propylene-ethylene) copolymer, per 100 parts by weight of a water-soluble epoxy resin or vinyl acetate ethylene copolymer.

10. A method for manufacturing a cell pad for a secondary battery, characterized in that in paragraph 8, the expanded flame retardant composition comprises 20 to 40 parts by weight of melamine, 20 to 40 parts by weight of carbonyl diamide, and 30 to 50 parts by weight of D-glucitol per 100 parts by weight of ammonium polyphosphate.

Images