Heat dissipation composition for bus bar, and manufacturing method for bus bar assembly including the same

Abstract

To provide a heat dissipation composition for a bus bar exhibiting a high heat dissipation effect.SOLUTION: A heat dissipation composition includes a base resin and a phase change material, and the weight ratio between the base resin and the phase change material is about 2.8:1 to about 1.3:1. In addition, a manufacturing method for a bus bar assembly is provided, the method including: manufacturing a heat dissipation composition by mixing a phase change material with a base resin; and applying and drying the heat dissipation composition on an upper surface of the bus bar is also provided.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat dissipation composition for a busbar and a method for manufacturing a busbar assembly including the same. [Background technology]

[0002] In recent years, with the rapid spread of battery-powered electronic devices such as mobile phones, laptop computers, and electric vehicles, the demand for high-energy-density, high-capacity secondary batteries has rapidly increased. As a result, research and development efforts to improve the performance of lithium secondary batteries have been actively pursued.

[0003] Lithium secondary batteries have a higher energy density per unit weight and are capable of rapid charging compared to other secondary batteries such as conventional lead-acid batteries and nickel-cadmium batteries, and therefore their use is rapidly increasing.

[0004] Lithium secondary batteries have an operating voltage of 3.6V or more and are used as power sources for portable electronic devices. In addition, a large number of lithium secondary batteries are connected in series or parallel to be used in high-power electric vehicles and energy storage devices.

[0005] In cases where long-term operation or high-power operation is required, such as in electric vehicles, a pack configuration containing multiple batteries is preferred due to issues of output and capacity, and the output voltage and output current can be increased depending on the number of built-in batteries.

[0006] The passive propagation resistance (PPR) design of a battery is intended to prevent heat transfer from cell to cell. A battery pack is a modular system consisting of thousands of connected battery cells. If a fire occurs in one of the cells in the pack, PPR prevents the heat from transferring to the surrounding cells, making it essential for battery packs that contain a large number of battery cells.

[0007] Meanwhile, high-power battery modules are used for fast backup, but the temperature of the cells and busbars rises very rapidly when the cells are discharged. To prevent this, not only PPR design but also the design of heat dissipation structures for the busbars and cells increases material costs and reduces manufacturing efficiency.

[0008] Generally, a battery having a phase-change material embedded between each battery cell is disclosed to prevent a rapid increase or decrease in temperature of the battery cell, but no heat-dissipating composition is disclosed that is provided on a bus bar whose temperature rises rapidly when the battery cell is discharged and that prevents thermal runaway of the battery cell.

[0009] The above-mentioned information disclosed in the background of the invention is intended to enhance understanding of the background of the invention only, and may therefore include information that does not constitute prior art. Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a heat-dissipating composition for bus bars that exhibits a high heat-dissipating effect.

[0011] Another embodiment aims to provide a method for manufacturing a busbar assembly using the heat-dissipating composition.

[0012] Yet another embodiment is directed to an energy storage device including a bus bar coated with a heat dissipation composition and provided with a heat dissipation layer.

[0013] However, the technical problems that the present invention aims to solve are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Means for solving the problem]

[0014] One embodiment of the present invention to solve the above technical problem provides a heat-dissipating composition comprising a base resin and a phase-change material, wherein the weight ratio of the base resin to the phase-change material is about 2.8:1 to about 1.3:1.

[0015] Another embodiment provides a method for manufacturing a busbar assembly, including the steps of preparing a heat-dissipating composition by mixing a phase-change material into a base resin; and applying the heat-dissipating composition to an upper surface of a busbar and drying the composition.

[0016] Yet another embodiment is a method of using a thermal interface composition, comprising spraying or applying the thermal interface composition to an object, wherein the object comprises a bus bar, a battery cell, or a combination thereof.

[0017] Yet another embodiment provides an energy storage device including: a plurality of battery cells; a bus bar connected to electrode leads of the battery cells and connected to at least one of the battery cells; and a heat-dissipating layer provided on an upper portion of the bus bar and coated with the heat-dissipating composition. [Effects of the Invention]

[0018] The heat dissipation composition according to one embodiment of the present invention can be applied to a bus bar to impart excellent heat dissipation performance to the bus bar, and can also be compatible with PPR. Therefore, it can satisfy regulations on fire propagation due to thermal runaway of battery modules without the need for a separate fire extinguishing sheet.

[0019] The heat dissipation composition absorbs heat when the bus bar generates heat, effectively reducing the temperature of the bus bar, eliminating the need for a separate heat sink design for the bus bar.

[0020] The heat-dissipating composition exhibits not only the heat-dissipating function but also the fire-extinguishing function of existing fire-extinguishing sheets, thereby satisfying the regulations on fire spread due to thermal runaway and significantly reducing the manufacturing cost and takt time of the manufacturing process of energy storage devices.

[0021] However, the effects obtained through the present invention are not limited to the effects described above, and other technical effects not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Brief explanation of the drawings]

[0022] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention to be given later, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited solely to the matters shown in such drawings.

[0023] [Figure 1] 1 is a process flowchart of a method for manufacturing a busbar assembly according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view showing the structure of a bus bar disposed above a battery cell. [Figure 3] 3 is a view showing the attachment area of ​​the fire extinguishing sheet on the top of the battery cell according to FIG. 2. FIG. [Figure 4] FIG. 1 is a plan view of a busbar assembly according to an embodiment of the present invention. [Figure 5] 1 is a perspective view schematically illustrating a configuration of a battery cell in an energy storage device according to an embodiment of the present invention. [Figure 6] 1 is a cross-sectional view schematically illustrating a configuration of a battery cell in an energy storage device according to an embodiment of the present invention. [Figure 7] 1 is a perspective view of a battery module including a busbar assembly of a UPS module according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present invention will be described in detail, but these are presented as examples and are not intended to limit the present invention, which is defined only by the scope of the claims set forth below.

[0025] In this specification, unless otherwise specified, when a part such as a layer, film, region, or plate is said to be "on" another part, this includes not only the case where it is "directly on" the other part, but also the case where there is another part in between.

[0026] In this specification, unless otherwise specified, the singular can also include the plural. In addition, unless otherwise specified, "A or B" can mean "including A, including B, or including A and B."

[0027] As used herein, "combinations thereof" can mean mixtures, laminates, composites, copolymers, alloys, blends, reaction products, and the like of compositions.

[0028] In this specification, the term "layer" includes not only a shape formed on the entire surface when observed in a plan view, but also a shape formed on a part of the surface.

[0029] The "average particle size" can be measured by methods well known to those skilled in the art, such as by using a particle size analyzer or by using a transmission electron microscope or a scanning electron microscope. Alternatively, the average particle size can be obtained by measuring using a dynamic light scattering method, analyzing the data, counting the number of particles in each particle size range, and then calculating the average particle size. The average particle size can be measured using a microscope image or a particle size analyzer, and can refer to the diameter (D50) of particles whose cumulative volume is 50% by volume in the particle size distribution.

[0030] "Or" is not to be construed in an exclusive sense; for example, "A or B" is to be construed as including A, B, A+B, etc.

[0031] When describing a numerical range, "X to Y" means "X or more and Y or less (X≦and≦Y)."

[0032] In each illustrative example of a prismatic battery according to an embodiment of the present invention, one of a prismatic / pouch / circular battery is selected, and the selected battery is described as having a general structure, and in the case of a generally applicable technology, the general structure of a prismatic / pouch / circular battery is described.

[0033] Hereinafter, embodiments of the present invention will be described in detail, but these are presented as examples and are not intended to limit the present invention, which is defined only by the scope of the claims set forth below.

[0034] heat dissipation composition The heat-dissipating composition according to one embodiment includes a base resin and a phase change material (PCM).

[0035] Specifically, the heat dissipating composition may further include a fire extinguishing capsule and a flame retardant.

[0036] The base resin forms a polymeric matrix within which the phase change material and fire extinguishing agent can be contained.

[0037] The base resin can be applied directly to the heat source and then cured to provide a firm adhesion.

[0038] The base resin may include a polyurethane resin, a silicone resin, or a combination thereof.

[0039] The above-mentioned types of base resins form a matrix, can contain a phase-change material and a fire-extinguishing agent within the matrix, and exhibit viscosity before hardening, allowing for uniform application, making them easy to process. In addition, they have heat resistance, so even when continuously exposed to heat from the outside, the base resin does not deform and can release a portion of the heat transferred from the heat source to the outside.

[0040] The above types of base resins have high viscosity before hardening, making them easy to apply to the heat source, and are thermosetting resins. After the heat-dissipating composition is applied to the surface of the heat source, it is crosslinked and hardened by a catalyst or heat, allowing the phase-change material and fire-extinguishing capsules to be contained and fixed.

[0041] The weight ratio of base resin to phase change material can be from about 2.8:1 to about 1.3:1 (e.g., 2.8, 2.7, 2.6, 2.5, 2.4, 2.3, 2.2, 2.1, 2.0, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, or 1.3:1).

[0042] Within the above weight ratio of the base resin to the phase change material, the heat-dissipating composition can exhibit a higher temperature reduction effect than when a heat-dissipating sheet is attached.

[0043] In one embodiment, the base resin is included in the heat-dissipating composition in an amount of about 50 parts by weight to about 70 parts by weight (e.g., 50 parts by weight, 51 parts by weight, 52 parts by weight, 53 parts by weight, 54 parts by weight, 55 parts by weight, 56 parts by weight, 57 parts by weight, 58 parts by weight, 59 parts by weight, 60 parts by weight, 61 parts by weight, 62 parts by weight, 63 parts by weight, 64 parts by weight, 65 parts by weight, 66 parts by weight, 67 parts by weight, 68 parts by weight, 69 parts by weight, or 70 parts by weight).

[0044] When the base resin is contained in the heat-dissipating composition within the above range, it exhibits viscosity, which not only makes it easier to apply evenly to the surface of the heat source before curing, but also reduces the manufacturing cost of the heat-dissipating composition.

[0045] A phase change material is a material that is used to store energy or maintain a constant temperature by absorbing or releasing latent heat. Latent heat refers to heat absorbed or released at the same temperature when a material changes phase, for example, from solid to liquid, or from liquid to solid, or from liquid to gas, or from gas to liquid. The amount of latent heat is much greater than the amount of sensible heat, which is heat absorbed or released without a phase change.

[0046] A phase-change material may gradually increase in temperature when the surrounding temperature increases due to heat generated by a heat source, and gradually decrease in temperature when the surrounding temperature is low. For example, if the phase-change material has an intrinsic phase change temperature (TPC) or is stored at a certain temperature, the phase-change material changes phase within that temperature range, releasing or storing heat and raising or lowering the surrounding temperature. When moved from a low-temperature location to a high-temperature location, the phase-change material may change from solid to liquid, absorbing heat from the surroundings and cooling the surroundings, thereby exhibiting an endothermic effect. On the other hand, when moved from a high-temperature location to a low-temperature location, the phase-change material may change from liquid to solid, releasing heat to the surroundings and increasing the surrounding temperature.

[0047] In one embodiment, the phase change material may include at least one of a paraffin-based phase change material, an organic phase change material, an inorganic phase change material, and a eutectic phase change material.

[0048] For example, the organic phase change material may be one or more of paraffin C16-C19, polyglycol E600, paraffin wax, paraffin C16-C28, paraffin C20-C33, paraffin C13-C24, 1-dodecanol, 1-tetradecanol, paraffin C18, and vinyl stearate.

[0049] The inorganic phase change material may be one or more of CaCl2·6H2O, Zn(NO3)2·6H2O, KF·4H2O, Na2S2O3·5H2O, Na2SO4·10H2O, Mn(NO3)2·6H2O, LiNO3·3H2O, and Na(CH3COO)·3H2O.

[0050] Eutectic phase change materials are approximately 47% Ca(NO3)2·4H2O + approximately 33% Mg(NO3)2·6H2O, approximately 37.5% urea + approximately 63.5% acetamide, approximately 48% CaCl2 + approximately 4.3% NaCl + approximately 0.4% KCl + approximately 47.3% H2O, approximately 66.6% CaCl2·6H2O + approximately 33.3% MgCl2·6H2O, approximately The mixture may be one or more of 60% Na(CH3COO)·3H2O + about 40% CO(NH2), about 61.5% Mg(NO3)2·6H2O + about 38.5% NH4NO3, about 58.7% Mg(NO3)·6H2O + about 41.3% MgCl2·6H2O, and about 67.1% naphthalene + about 32.9% benzoic acid.

[0051] The phase change material may be contained in the base resin matrix in the form of microcapsules, specifically having an average particle size of about 100 μm or less (e.g., 100 μm, 99 μm, 98 μm, 97 μm, 96 μm, 95 μm, 94 μm, 93 μm, 92 μm, 91 μm, 90 μm, 89 μm, 88 μm, 87 μm, 86 μm, 85 μm, 84 μm, 83 μm, 82 μm, 81 μm, 80 μm, 79 μm, 78μm, 77μm, 76μm, 75μm, 74μm, 73μm, 72μm, 71μm, 70μm, 69μm, 68μm, 67μm, 66μm, 65μm m, 64μm, 63μm, 62μm, 61μm, 60μm, 59μm, 58μm, 57μm, 56μm, 55μm, 54μm, 53μm, 52μm, 51 μm, 50μm, 49μm, 48μm, 47μm, 46μm, 45μm, 44μm, 43μm, 42μm, 41μm, 40μm, 39μm, 38μm, 37μm, 36μm, 35μm, 34μm, 33μm, 32μm, 31μm, 30μm, 29μm, 28μm, 27μm, 26μm, 25μm, 24μm , 23 μm, 22 μm, 21 μm, 20 μm, 19 μm, 18 μm, 17 μm, 16 μm, 15 μm, 14 μm, 13 μm, 12 μm, 11 μm, 10 μm, 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2 μm, or 1 μm), preferably from about 1.5 μm to about 90 μm.

[0052] The phase change material may be contained in the base resin matrix in the form of capsules, and may be encapsulated using any one of the following methods: encapsulation using a coacervation reaction of gelatin and gum arabic, encapsulation using coco fatty acid and a phase change material, encapsulation using n-hexadecane and PMMA (Poly methyl methacrylate), encapsulation of PEG (Poly ethylene glycol) with acrylic polymer, and encapsulation using polyvinyl acetate and tetradecane.

[0053] When the phase-change material is in capsule form, it can be easily dispersed uniformly in the base resin, and after being applied to the surface of the heat source, the mechanical properties can be improved and the phase change temperature of the phase-change material can be easily controlled.

[0054] The capsule form is preferred because it allows for easier mixing into the base resin than when the phase change material is directly impregnated into the base resin or when it is a shape-stabilized phase change material.

[0055] The phase change material may have a phase change temperature of about 35°C to about 45°C (e.g., 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, or 45°C).

[0056] The heat dissipation composition may be applied to the bus bar of a battery. Typically, the operating temperature of a battery cell is controlled at about 20°C to about 26°C. When the temperature increases due to high power output and reaches this range, the phase change material absorbs heat, cooling not only the bus bar but also the surrounding battery cells.

[0057] The phase change temperature can be adjusted by selecting the type of phase change material. For example, C16 to C19 paraffin (C 19 H 40 , C 18 H 38 , C16 H 34 ), the melting point is about 18° C. to about 33° C., so it is possible to adjust the phase change temperature of the phase change material by selecting the paraffin-based phase change material.

[0058] The phase change material is included in the heat-dissipating composition in an amount of about 20 parts by weight to about 40 parts by weight (e.g., 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 37 parts by weight, 38 parts by weight, 39 parts by weight, or 40 parts by weight).

[0059] Within the above range, the latent heat is increased, sufficient heat dissipation performance is exhibited upon contact with a heat source, and temperature control of the area where the heat dissipation composition is applied and the surrounding area is possible. Specifically, when the heat dissipation composition is applied to the surface of a bus bar, a sudden increase in temperature during high-power charging and discharging of a battery cell can be prevented. Furthermore, since phase change materials have a very high viscosity, when the viscosity falls within the above range, the heat dissipation composition can be adjusted to a level that allows application, and the heat dissipation composition can be uniformly applied using a spray or brush. Since phase change materials are flammable, a flame retardant can be further added within the range described below to prevent combustion of the phase change material. Furthermore, this increases the process takt time, and the inclusion of a flame retardant allows the UL94 V-2 standard to be met.

[0060] The fire extinguishing agent can impart its own fire extinguishing function to the heat-dissipating composition. The fire extinguishing agent is preferably a fire extinguishing capsule contained in a capsule. When the heat-dissipating composition reaches a target temperature, the fire extinguishing agent contained in the fire extinguishing capsule is sprayed to prevent combustion of the battery module due to thermal runaway of the battery cell, which is a heat source.

[0061] The fire-extinguishing agent may be contained within the base resin matrix in the form of microcapsules, such as micro-sized fire-extinguishing capsules having an average diameter of about 10 μm to about 80 μm (e.g., 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, or 80 μm), preferably about 10 μm to about 50 μm.

[0062] When the fire-extinguishing capsules are contained in the form of microcapsules, they can be uniformly dispersed within the matrix of the base resin, which not only increases manufacturing efficiency but also allows the agent to be dispersed very uniformly by the fire-extinguishing capsules when heat above the reaction temperature is generated from the heat source, making it possible to more effectively extinguish a fire in a battery cell.

[0063] The fire extinguishing agent may have a reaction temperature of about 140°C to about 180°C (eg, 140°C, 150°C, 160°C, 170°C, or 180°C).

[0064] The heat-dissipating composition may be applied directly to the surface of the bus bar, for example. Since the temperature at which thermal runaway occurs due to a temperature increase in a battery cell is typically around 200°C, if the fire-extinguishing agent has a reaction temperature within the above range, the agent in the fire-extinguishing capsule, which has reached its reaction temperature due to a temperature increase before the battery cell ignites, is pre-injected into the battery cell, effectively suppressing initial combustion of the battery cell and preventing subsequent fires and thermal runaway of the battery cell. If the reaction temperature range of the fire-extinguishing agent is lower than the above reaction temperature, the fire-extinguishing agent will activate before the cell temperature rises too much, and the fire-extinguishing capsule will be in a reacted state under the actual cell fire conditions, resulting in no agent diffusion effect.

[0065] In one embodiment, the fire extinguishing capsule may include a perfluoro group.

[0066] The perfluoro-containing compound can have, for example, the molecular structure 2-methyl-3-pentanone, which is a highly effective gaseous fire extinguishing agent. The fire extinguishing capsule can be in the form of a capsule having a core of fire extinguishing agent surrounded by a shell containing gelatin, formalin, and a polymeric binder.

[0067] When a compound containing a perfluoro group is contained as a fire-extinguishing agent in a fire-extinguishing capsule and a shell containing gelatin is provided, the fire-extinguishing agent does not react with the base resin while maintaining fire-extinguishing power, and the fire-extinguishing agent is instantly sprayed by the reaction of the fire-extinguishing capsule at the reaction temperature, so that the fire-extinguishing agent can be filled into the battery cell before the battery cell burns.

[0068] The fire extinguishing agent may be included in the heat dissipating composition at about 1 part by weight to about 10 parts by weight (e.g., 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, or 10 parts by weight).

[0069] Within the above range, the heat-dissipating composition contains a fire-extinguishing agent, which satisfies regulations on the spread of fire due to thermal runaway, and can extinguish fires not only in the busbar but also in the battery cells surrounding the busbar assembly, while minimizing manufacturing costs within the standard range.

[0070] The flame retardant can inhibit the combustion of the phase change material.

[0071] Since the phase change material is flammable, if the heat-dissipating composition contains a flame retardant, the heat-dissipating composition applied to the heat source can suppress combustion caused by the phase change material.

[0072] The flame retardant may include a phosphorus-based flame retardant, a non-halogen flame retardant, or a combination thereof. For example, the phosphorus-based flame retardant may be an organic phosphorus compound, an organic phosphate compound, or a mixture thereof. For example, the organic phosphorus compound may be red phosphorus, phosphoric acid, melamine orthophosphate, melamine pyrophosphate, melamine polyphosphate, melamine phosphate, etc., and the organic phosphate compound may be piperazine orthophosphate, piperazine pyrophosphate, piperazine polyphosphate, etc. Specifically, the phosphorus-based flame retardant may be a red phosphorus-based flame retardant.

[0073] The non-halogen flame retardant may be a phosphate ester flame retardant, ammonium polyphosphate, red phosphorus, magnesium hydroxide, aluminum hydroxide, expandable graphite, etc. For example, the phosphate ester flame retardant may be one or more of triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, tris(isopropylphenyl)phosphate, tris(o- or p-phenylphenyl)phosphate, trinaphthyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, diphenyl(2-ethylhexyl)phosphate, di(isopropylphenyl)phenyl phosphate, o-phenylphenyldicresyl phosphate, tris(2,6-dimethylphenyl)phosphate, tetraphenyl-m-phenylenediphosphate, tetraphenyl-p-phenylenediphosphate, phenylresorcinol polyphosphate, bisphenol A bis(diphenyl phosphate), bisphenol A polyphenyl phosphate, and dipyrocatechol hypodiphosphate.

[0074] The flame retardant may be included in the heat dissipating composition at about 1 part by weight to about 10 parts by weight (e.g., 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, or 10 parts by weight).

[0075] The inclusion of the above-mentioned types of flame retardants can effectively inhibit the combustion of the phase change material, increase the compatibility with the base resin, and do not affect the viscosity of the heat-dissipating composition, making it easier to apply the heat-dissipating composition.

[0076] The flame retardant can meet the V-2 standard of the UL94 standard.

[0077] Since the heat-dissipating composition of the present embodiment contains a flame retardant, it is not directly burned by the flame generated in the event of a fire in the battery cell and can have self-extinguishing properties.

[0078] The heat dissipating composition may have a latent heat of about 40 kJ / kg or more when potting the bus bar.

[0079] The heat dissipating composition may be applied to the surface of the bus bar and potted into the bus bar assembly, and may have a latent heat capacity of about 40 kJ / kg or greater, specifically about 40 kJ / kg to about 60 kJ / kg (e.g., 40 kJ / kg, 41 kJ / kg, 42 kJ / kg, 43 kJ / kg, 44 kJ / kg, 45 kJ / kg, 46 kJ / kg, 47 kJ / kg, 48 kJ / kg, 49 kJ / kg, 50 kJ / kg, 51 kJ / kg, 52 kJ / kg, 53 kJ / kg, 54 kJ / kg, 55 kJ / kg, 56 kJ / kg, 57 kJ / kg, 58 kJ / kg, 59 kJ / kg, or 60 kJ / kg).

[0080] If the latent heat amount is within the above range, when the temperature of the battery cell increases due to high output, the heat transferred to the bus bar connected to the battery lead terminal can be sufficiently absorbed, preventing the bus bar from overheating, and the heat can be removed from the battery cell, thereby helping to cool the battery cell.

[0081] The heat dissipation composition according to the present invention can be directly potted onto a bus bar to form a bus bar assembly, which not only controls the temperature increase of the bus bar due to the output characteristics of the battery but also cools the battery cell. It also sets a temperature zone where the fire extinguishing agent reacts at a temperature above the phase change temperature of the phase change material, allowing the fire extinguishing agent to be uniformly dispersed within the battery cell when the battery cell burns, thereby not only extinguishing an initial fire in the battery cell but also preventing thermal runaway and enabling PPR design.

[0082] Method of using the heat dissipating composition The heat-dissipating composition is used by spraying or applying the composition to a heat-dissipating object, thereby enabling heat transfer from a heat source to the heat-dissipating composition. The composition can also be applied to the object, such as a bus bar, a battery cell, or both a bus bar and a battery cell, to ensure heat dissipation performance.

[0083] Busbar assembly manufacturing Another embodiment of the present invention relates to a method for manufacturing a busbar assembly.

[0084] FIG. 1 is a process flowchart of a method for manufacturing a busbar assembly according to one embodiment of the present invention.

[0085] Referring to FIG. 1, a method for manufacturing a busbar assembly includes the steps of preparing a heat-dissipating composition by mixing a phase-change material into a base resin; and applying the heat-dissipating composition to an upper surface of a busbar and drying it.

[0086] First, a phase change material and a fire extinguishing agent are mixed with a base resin to prepare a heat dissipating composition (S100).

[0087] In one embodiment, a fire extinguishing agent and a flame retardant can be further added to and mixed with the base resin to produce a heat dissipating composition.

[0088] The prepared heat-dissipating composition has the same composition as the heat-dissipating composition described above, so a repeated description will be omitted.

[0089] In one embodiment, the heat dissipating composition includes about 50 parts by weight to about 70 parts by weight of a base resin, about 20 parts by weight to about 40 parts by weight of a phase change material, about 1 part by weight to about 10 parts by weight of a fire extinguishing agent, and about 1 part by weight to about 10 parts by weight of a flame retardant.

[0090] Within the above ranges, the heat-dissipating composition can be prepared by adding the phase-change material, the fire-extinguishing agent, and the flame retardant to the base resin and stirring them.

[0091] The heat dissipating composition thus produced has viscosity, so that it can be applied directly to a bus bar and potted onto the bus bar to form a bus bar assembly.

[0092] Next, the prepared heat-dissipating composition is directly applied to the upper surface of the bus bar and dried (S200).

[0093] The heat-dissipating composition may be directly potted onto the surface of the busbar by coating or the like, or it may be potted after a heat-dissipating composition sheet is produced by first adapting the heat-dissipating composition to the shape of the busbar and then coating a primer on the surface of the busbar. However, since the heat-dissipating composition is viscous and does not react with metal busbars, drying and curing the composition after application can reduce the takt time of the process.

[0094] In one embodiment, the heat dissipation composition may be applied to the upper surface of the busbar in the area where the fire extinguishing sheet is attached.

[0095] FIG. 2 is a plan view showing the structure of a bus bar arranged on the top of a battery cell, FIG. 3 is a view showing an attachment area of ​​a fire extinguishing sheet on the top of the battery cell according to FIG. 2, and FIG. 4 is a plan view of a bus bar assembly according to one embodiment of the present invention.

[0096] 2 to 4, the bus bar 300 may electrically connect each cell with a longitudinal member and include grid points 1 where horizontal members and vertical members intersect. Fire extinguishing sheets 2 may be attached to the grid points 1. A heat dissipation composition may be applied not only to the surface of the bus bar 300 but also to the grid points 1 to form a heat dissipation layer 400. Because the heat dissipation composition contains a fire extinguishing agent, it can replace a fire extinguishing sheet that extinguishes a fire in the event of a fire in a battery cell. Specifically, the heat dissipation layer made of the heat dissipation composition replaces the fire extinguishing sheet 2, thereby reducing manufacturing costs and shortening the process.

[0097] In one embodiment, the heat dissipating composition can be applied to the surface of the busbar 300 to a thickness of about 1 mm or more, for example, about 16 mm or more, and specifically, can be applied to have a thickness of about 16 mm to about 25 mm (e.g., 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, or 25 mm), preferably about 16 mm to about 20 mm, or about 16 mm.

[0098] The heat-dissipating layer 400 containing the heat-dissipating composition in the above range can be firmly formed to constitute a busbar assembly, and if the content exceeds the above range, it may affect the cooling flow path and the battery module case structure.

[0099] When the heat-dissipating composition is applied to the busbar 300, the maximum temperature of the busbar during heat generation can be reduced by about 20°C or more compared to when the heat-dissipating composition is not applied to the busbar 300. For example, when the heat-dissipating layer 400 is not formed, the maximum temperature of the busbar 300 due to initial high output increases to about 114°C or more, but when the heat-dissipating layer 400 including the heat-dissipating composition is used to form a busbar assembly, the temperature of the busbar 300 can be reduced to 95°C or less.

[0100] In one embodiment, the latent heat content of the heat dissipating composition may be about 40 kJ / kg or greater, for example, from about 40 kJ / kg to about 60 kJ / kg (e.g., 40 kJ / kg, 41 kJ / kg, 42 kJ / kg, 43 kJ / kg, 44 kJ / kg, 45 kJ / kg, 46 kJ / kg, 47 kJ / kg, 48 kJ / kg, 49 kJ / kg, 50 kJ / kg, 51 kJ / kg, 52 kJ / kg, 53 kJ / kg, 54 kJ / kg, 55 kJ / kg, 56 kJ / kg, 57 kJ / kg, 58 kJ / kg, 59 kJ / kg, or 60 kJ / kg), or about 40 kJ / kg.

[0101] When the heat dissipation composition is applied to the surface of the busbar 300 to a thickness of about 16 mm or more, and then potted onto the heat dissipation layer after curing, the latent heat increases within the above range due to the phase change material contained in the heat dissipation layer 400, thereby not only preventing an increase in the temperature of the busbar 300 itself but also cooling it by absorbing heat from the surrounding battery cells.

[0102] In one embodiment, the reaction temperature of the fire-extinguishing agent may be about 140°C to about 180°C (e.g., 140°C, 150°C, 160°C, 170°C, or 180°C). The fire-extinguishing agent may be a micro-sized fire-extinguishing capsule. Specifically, the fire-extinguishing capsule contains a perfluoro group in its core, and the reaction temperature can be adjusted by adjusting the compound content and shell thickness. When the reaction temperature is set within this range, the fire-extinguishing agent diffuses into the battery cells around the busbar assembly at a temperature lower than about 200°C, the ignition temperature of the battery cells, during actual operation. This is highly effective in extinguishing an initial fire caused by overheating of the battery cells and preventing subsequent ignition of the battery cells. If the reaction temperature is lower than this range, the fire-extinguishing agent will activate before the battery cell temperature rises significantly, and will not be able to exhibit a fire-extinguishing effect.

[0103] Energy Storage Device Another embodiment of the present invention relates to an energy storage device.

[0104] The energy storage device includes a plurality of battery cells, a bus bar, and a heat dissipation layer.

[0105] FIG. 5 is a perspective view schematically showing the configuration of a battery cell in an energy storage device according to one embodiment of the present invention, and FIG. 6 is a cross-sectional view schematically showing the configuration of a battery cell in an energy storage device according to one embodiment of the present invention.

[0106] 5 and 6, the battery cell 200 may include at least one electrode assembly 10 wound between a positive electrode 11 and a negative electrode 12 with a separator 13, which is an insulator, interposed therebetween; a case 20 in which the electrode assembly 10 is housed; and a cap assembly 30 coupled to an opening of the case 20.

[0107] The battery cell 200 will be described as a rectangular lithium ion secondary battery, but the present invention is not limited thereto, and the battery cell 200 may be a lithium polymer battery or a cylindrical battery.

[0108] The positive electrode 11 and the negative electrode 12 may include a coated portion, which is an area where an active material is applied to a current collector formed of a thin metal foil, and a plain portion 11a, 12a, which is an area where the active material is not coated.

[0109] The positive electrode 11 and the negative electrode 12 may be wound up after being sandwiched between an insulating separator 13. However, the present invention is not limited thereto, and the electrode assembly 10 may have a structure in which positive electrodes and negative electrodes made of a plurality of sheets are alternately stacked with separators sandwiched between them.

[0110] The case 20 forms the overall appearance of the battery cell 200 and may be made of a conductive metal such as aluminum, an aluminum alloy, or nickel-plated steel. The case 20 may also provide a space in which the electrode assembly 10 is housed.

[0111] The cap assembly 30 may include a cap plate 31 that covers the opening of the case 20, and the case 20 and the cap plate 31 may be made of a conductive material. Here, positive and negative electrode terminals 21 and 22 electrically connected to the positive electrode 11 or the negative electrode 12 may be installed to penetrate the cap plate 31 and protrude outward.

[0112] The outer peripheral surfaces of the upper pillars of the positive and negative terminals 21, 22 protruding outward from the cap plate 31 may be threaded or may be fixed to the cap plate 31 with nuts.

[0113] However, the present invention is not limited thereto, and the positive and negative terminals 21, 22 may have a rivet structure and be riveted together, or may be welded to the cap plate 31.

[0114] The cap plate 31 may be made of a thin plate and may be coupled to the opening of the case 20. The cap plate 31 may be formed with an electrolyte injection port 32 in which a sealing plug 33 may be installed, and may be provided with a vent 34 having a notch 34a.

[0115] The vent 34 may be opened and closed in response to changes in the internal pressure of the case 20. That is, the vent 34 may maintain a closed state during normal operation of the electrode assembly 10, thereby sealing the case 20. The vent 34 may be opened when the internal pressure of the case 20 rises above a predetermined level due to overcharging, a fire, or the like, thereby allowing emissions such as flames and gases to be discharged from the inside of the case 20 to the outside of the case 20.

[0116] The positive and negative electrode terminals 21, 22 may be electrically connected to current collectors including first and second current collectors 40, 50 (hereinafter also referred to as positive and negative electrode current collectors) joined by welding to the positive electrode uncoated region 11 a or the negative electrode uncoated region 12 a.

[0117] For example, the positive and negative electrode terminals 21, 22 may be connected to the positive and negative electrode current collectors 40, 50 by welding. However, the present invention is not limited thereto, and the positive and negative electrode terminals 21, 22 and the positive and negative electrode current collectors 40, 50 may be integrally connected to each other.

[0118] FIG. 7 is a perspective view of a battery module including a bus bar assembly according to one embodiment of the present invention.

[0119] Referring to FIG. 7, one end of the bus bar 300 is connected to the electrode lead 210 of the battery cell 200, and the bus bar 300 may be connected to at least one battery cell 200 to form a bus bar assembly.

[0120] The heat dissipation layer 400 is formed by applying a heat dissipation composition to the surface of the bus bar 300, and can control the temperature increase of the bus bar 300.

[0121] The provision of the heat dissipation layer 400 can prevent the temperature of the bus bar 300 from rising, so that the bus bar 300 does not require a separate heat sink or heat storage structure, greatly simplifying the bus bar assembly structure.

[0122] The busbar assembly includes a heat dissipation layer 400, which has a temperature zone that limits the temperature increase of the busbar 300 and a reaction temperature zone that injects a fire-extinguishing agent before ignition, which are set in different shapes. This not only suppresses a rapid temperature increase of the busbar due to high output during the initial operation of the battery and improves the operational stability of the busbar 300, but also, when the temperature transferred to the busbar 300 due to an increase in the temperature of the battery cell 200 reaches the reaction temperature zone, the fire-extinguishing agent is injected when the battery cell 200 burns, which is very effective in extinguishing an initial fire in the battery cell 200, prevents thermal runaway of the battery cell 200, and enables a PPR design.

[0123] In one embodiment, the uninterruptible power supply can meet regulations such as thermal runaway fire propagation regulations.

[0124] Examples and comparative examples of the present invention will be described below. However, the following examples are merely examples of the present invention, and the present invention is not limited to the following examples.

[0125] Examples 1 to 3 Heat-dissipating compositions were prepared by mixing a phase-change material (KCC, PCM urethane) with polyurethane resin in an amount adjusted as shown in Table 1 below, and a fire extinguishing agent and a flame retardant were additionally mixed in (Example 1). Heat-dissipating compositions were prepared by adjusting the amount of phase-change material (KCC, PCM urethane) without additionally mixing in a fire extinguishing agent and a flame retardant (Example 2). Finally, a heat-dissipating composition was prepared by selecting silicon (KCC, PCM silicon) as the phase-change material (Example 3). The prepared heat-dissipating composition was applied to a surface of a bus bar (specific heat 0.893 J / g°C, mass 83.9 g) to a thickness of 16 mm and dried to form a heat-dissipating layer.

[0126] Comparative Example 1 The same bus bar as in the example was not formed with a heat dissipation layer.

[0127] Comparative Example 2 Heat dissipation silicon was applied to the same bus bar as in the example to the same thickness to form a heat dissipation layer.

[0128] Experimental example

[0129] [Table 1]

[0130] The busbars were 1m long, their thickness adjusted according to our busbar manufacturing standards, and their ends secured with bolts. A heat-dissipating layer was formed by applying a heat-dissipating compound to the center of the busbar, and temperature changes were measured by placing a thermostat on the heat-dissipating layer.

[0131] Table 1 shows the results of measuring the maximum temperature of the busbar after applying the heat-dissipating compositions prepared in the examples and comparative examples to the busbar to form a heat-dissipating layer. A 50g sample was taken from each heat-dissipating composition and potted onto the busbar. A current of 600A was applied at room temperature for 7 minutes, and the maximum temperature of the busbar was then measured.

[0132] Referring to Table 1, in Examples 1 to 3, the maximum temperatures of the bus bars were measured at 91.2°C to 94.63°C, which was confirmed to be a temperature reduction of more than 20°C compared to the maximum temperature of 114.28°C in Comparative Example 1, which was not provided with a heat dissipation layer. In addition, a temperature reduction effect of more than 10°C was confirmed compared to Comparative Example 2, which was coated with heat dissipation silicone, which is commonly used as a conventional heat dissipation material.

[0133] [Table 2]

[0134] Meanwhile, the temperature change inside the battery cell was measured when a heat dissipation layer was provided and when no heat dissipation layer was provided. A thermocouple was attached to the center of the long side of the battery cell, and the temperature was measured using this. A temperature decrease of 4 to 5°C was observed compared to Comparative Example 1, based on the battery cell of Example 3, and it was confirmed that when a heat dissipation layer was provided, the temperature inside the cell was also reduced.

[0135] Therefore, it was confirmed that when the heat dissipation composition according to the embodiment is applied to a bus bar to form a heat dissipation layer, it can effectively respond to the temperature increase of the bus bar and exhibit a cooling effect on the battery cell, thereby making it possible to construct a more stable battery module.

[0136] In addition, in Example 1, a fire retardant and a fire extinguishing capsule are included, and the fire extinguishing agent can be diffused into the battery cells around the busbar assembly at a temperature lower than 200°C, which is the ignition temperature of the battery cells. This is very effective in extinguishing an initial fire caused by overheating of the battery cells, and can prevent subsequent ignition of the battery cells.

[0137] Although the above describes preferred embodiments of the present invention, the present invention is not limited thereto and can be embodied in various modifications within the scope of the claims, the detailed description of the invention, and the accompanying drawings, which of course also fall within the scope of the present invention. [Explanation of symbols]

[0138] 1 grid point 2. Fire extinguishing sheet 11 Positive electrode 12 Negative electrode 13 Separator 20 cases 30 Cap Assembly 31 Cap plate 32 Electrolyte inlet 33 Sealing stopper 34 Vent 40 First current collector 50 Second current collector 200 battery cells 210 Electrode Lead 300 Busbar 400 Heat dissipation layer 1000 uninterruptible power supply

Claims

1. A heat dissipation composition comprising a base resin and a phase change material, The heat-dissipating composition, wherein the weight ratio of the base resin to the phase-change material is from about 2.8:1 to about 1.3:

1.

2. 10. The heat-dissipating composition of claim 1, wherein the heat-dissipating composition comprises about 50 to about 70 parts by weight of the base resin, about 20 to about 40 parts by weight of a phase change material, about 1 to about 10 parts by weight of a fire extinguishing agent, and about 1 to about 10 parts by weight of a flame retardant.

3. The heat dissipation composition of claim 1 , wherein the base resin comprises a polyurethane resin, a silicone resin, or a combination thereof.

4. 10. The heat dissipating composition of claim 1, wherein the phase change material has a phase change temperature of about 35°C to about 45°C.

5. The heat-dissipating composition of claim 2 , wherein the base resin forms a matrix, and the phase-change material is contained in the matrix in the form of microcapsules.

6. 6. The heat dissipating composition of claim 5, wherein the fire extinguishing agent is contained within the base resin matrix in the form of microcapsules.

7. 3. The heat dissipating composition of claim 2, wherein the reaction temperature of the fire extinguishing agent is from about 140°C to about 180°C.

8. The heat dissipating composition of claim 6 , wherein the fire extinguishing agent comprises a perfluoro group.

9. 3. The heat dissipating composition of claim 2, wherein the flame retardant comprises a phosphorus-based flame retardant, a non-halogen flame retardant, or a combination thereof.

10. The heat dissipating composition according to claim 9, wherein the flame retardant satisfies the V-2 standard of the UL94 standard.

11. 11. A method of using the heat dissipating composition of any one of claims 1 to 10, said method comprising: spraying or applying the heat-dissipating composition to an object; The object comprises a bus bar, a battery cell, or a combination thereof.

12. preparing a heat dissipation composition by mixing a phase change material into a base resin; and applying the heat dissipation composition to an upper surface of the bus bar and allowing it to dry.

13. The heat-dissipating composition is A heat dissipation composition comprising a base resin and a phase change material, The method of claim 12, wherein a weight ratio of the base resin to the phase change material is from about 2.8:1 to about 1.3:

1.

14. 14. The method of claim 13, wherein the heat dissipation composition comprises about 50 to about 70 parts by weight of the base resin, about 20 to about 40 parts by weight of a phase change material, about 1 to about 10 parts by weight of a fire extinguishing agent, and about 1 to about 10 parts by weight of a flame retardant.

15. The method for manufacturing a busbar assembly according to claim 12 , wherein the heat-dissipating composition is applied to the upper surface of the busbar, including the area where the fire-extinguishing sheet is attached.

16. The method of manufacturing a busbar assembly of claim 12 , wherein the busbar does not include a heat sink.

17. The method of claim 12 , wherein the heat-dissipating composition is applied to the surface of the bus bar to a thickness of about 16 mm or greater.

18. The method for manufacturing a busbar assembly according to claim 17 , wherein the maximum temperature of the busbar during heat generation is reduced by at least about 20° C. compared to when the heat-dissipating composition is not applied to the busbar.

19. The method of claim 14, wherein the heat dissipation composition has a latent heat content of about 40 kJ / kg or greater.

20. The method of claim 14, wherein the reaction temperature of the fire extinguishing agent is from about 140°C to about 180°C.

21. a plurality of battery cells; a bus bar connected to the electrode lead of the battery cell and connected to at least one battery cell; and a heat dissipation layer provided on an upper portion of the bus bar and coated with the heat dissipation composition according to any one of claims 1 to 10.

22. 22. The energy storage device of claim 21, wherein the energy storage device meets thermal runaway propagation regulations.

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