Gap filler composition and battery pack

Abstract

A gap filler composition according to embodiments of the present invention comprises: a siloxane-based resin; a filler including thermally conductive inorganic particles, hollow particles, and graphite particles; and a catalyst. The crushing strength of the hollow particles is 1,000 psi or more. Provided is a gap filler composition using hollow particles and graphite particles and having a low specific gravity, high thermal conductivity, and improved viscosity stability. Provided is a battery pack using the gap filler composition.

Description

Gap filler composition and battery pack

[0001] The present invention relates to a gap filler composition and a battery pack. More particularly, the present invention relates to a gap filler composition comprising a siloxane-based resin and a battery pack comprising a gap filler formed using the same.

[0002]

[0003] Secondary batteries, which can be repeatedly charged and discharged, are widely used as power sources for portable electronic devices such as cell phones and laptops. For example, lithium secondary batteries boast high operating voltage, energy density, and rate characteristics, and are recently being utilized as power sources for electric vehicles.

[0004] For example, a battery cell is defined by a lithium secondary battery, and a plurality of battery cells are assembled to form a battery module. The battery modules can be assembled to form a high-capacity / high-output battery pack applicable to electric vehicles.

[0005] To apply the battery pack to a vehicle such as an electric vehicle, the battery pack can be secured to a battery support plate and a gap filler composition can be used to secure the battery pack.

[0006] The above gap filler composition application process can be incorporated into the overall electric vehicle production platform. Therefore, to maintain automotive process efficiency and reliability, a gap filler composition that cures within a predetermined time and provides desired properties may be required.

[0007] There is a need to design a composition that can form a gap filler having improved thermal conductivity for dissipating heat generated by repeated charging / discharging of the battery pack, and having appropriate absorbency / elasticity against external impact while having low weight / specific gravity.

[0008] For example, Korean Patent Publication No. 10-2402503 discloses a battery pack structure including a battery module and a gap filler. However, it does not disclose the specific properties and composition of the gap filler.

[0009]

[0010] One object of the present invention is to provide a gap filler composition that provides improved thermal and mechanical properties.

[0011] One object of the present invention is to provide a battery pack including a gap filler formed of the gap filler composition.

[0012]

[0013] 1. A gap filler composition comprising a siloxane resin; a filler including thermally conductive inorganic particles, hollow particles and graphite particles; and a catalyst, wherein the hollow particles have a crushing strength of 1,000 psi or more.

[0014] 2. A gap filler composition in the above 1, wherein the crushing strength of the hollow particles is 2,000 psi to 60,000 psi.

[0015] 3. In the above 1, the gap filler composition comprises hollow silica particles.

[0016] 4. A gap filler composition in the above 1, wherein the content of the hollow particles is 1% to 5% by weight of the total weight of the composition.

[0017] 5. In the above 1, the gap filler composition comprises spherical graphite.

[0018] 6. In the above 1, the sphericity of the graphite particles according to the following formula 1 is 0.5 to 0.95, a gap filler composition:

[0019] [Formula 1]

[0020] Sphericity (D) s ) = l x / l y

[0021] (In the above equation 1, l x is the average of the major axis lengths of 10 to 30 particles included in the SEM images of graphite particles, and l y is the average of the short axis lengths of 10 to 30 particles included in the SEM images of graphite particles.

[0022] 7. A gap filler composition in the above 1, wherein the content of the graphite particles is 1 wt% to 12 wt% of the total weight of the composition.

[0023] 8. A gap filler composition in the above 1, wherein the content of the thermally conductive inorganic particles is 75% by weight to 95% by weight of the total weight of the composition.

[0024] 9. A gap filler composition further comprising an amino-silicone-based dispersant in the above 1, wherein the content of the amino-silicone-based dispersant is 0.1 wt% to 3 wt% of the total weight of the composition.

[0025] 10. A gap filler composition in the above 1, wherein the siloxane-based resin comprises a first siloxane-based resin including an unsaturated terminal group and a second siloxane-based resin including a saturated terminal group.

[0026] 11. A gap filler composition according to the above 10, wherein the siloxane-based resin further comprises a crosslinking agent including a siloxane-based resin having methyl groups bonded to silicon atoms at both terminals.

[0027] 12. A gap filler composition having a specific gravity of less than 2 in the above 1.

[0028] 13. A gap filler composition having a viscosity of 750 Paㆍs or less at 25℃ in the above 1.

[0029] 14. A battery pack comprising a plurality of battery modules; a support plate; and a gap filler formed between the battery modules and the support plate using the gap filler composition according to the embodiments described above.

[0030]

[0031] Gap filler compositions according to exemplary embodiments of the present invention may include hollow particles as fillers. Furthermore, the fillers may include graphite particles. The hollow particles may reduce the specific gravity of the gap filler composition, and the graphite particles may increase the thermal conductivity of the gap filler composition.

[0032] According to exemplary embodiments, hollow particles satisfying a predetermined range of crushing strengths may be used. In some embodiments, the hollow particles may be hollow silica particles. The specific gravity of the gap filler composition can be reduced by the hollow particles satisfying the predetermined range of crushing strengths.

[0033] According to exemplary embodiments, graphite particles satisfying a predetermined range of sphericity may be used. In some embodiments, the graphite particles may be spherical graphite. The thermal conductivity of the gap filler composition may be improved by graphite particles satisfying the above sphericity range.

[0034] Therefore, the above gap filler composition can be applied to a vehicle battery pack to reduce the weight of the battery pack and promote rapid heat dissipation even when the temperature increases due to repeated charging / discharging of the battery pack.

[0035]

[0036] FIG. 1 is a schematic cross-sectional view illustrating a battery pack according to exemplary embodiments.

[0037]

[0038] According to embodiments of the present invention, a gap filler composition comprising a siloxane-based resin, a catalyst, and a filler, and having improved curing properties and flowability is provided. Furthermore, according to embodiments of the present invention, a battery pack using the gap filler composition is provided.

[0039] Gap filler composition

[0040] A gap filler composition according to exemplary embodiments may include a siloxane-based resin, a catalyst, and a filler.

[0041] The above siloxane-based resin may be provided as a base component that provides curability to the gap filler composition. According to exemplary embodiments, the siloxane-based resin may include a first siloxane-based resin and a second siloxane-based resin.

[0042] The first siloxane-based resin may be a siloxane-based resin containing crosslinkable terminal groups. According to exemplary embodiments, the first siloxane-based resin may be a siloxane-based resin containing unsaturated terminal groups (e.g., vinyl groups) at both ends of the molecule.

[0043] For example, the first siloxane resin may include a compound represented by the following chemical formula 1.

[0044] [Chemical Formula 1]

[0045]

[0046] In some embodiments, 25 of the first siloxane resin o At C, the viscosity can be from 50 cps to 150,000 cps, from 70 cps to 1,500 cps, from 100 cps to 1,500 cps, from 200 cps to 1,500 cps, or from 300 cps to 1,200 cps.

[0047] Within the above viscosity range, the curing characteristics and curing speed described below can be more easily secured, and appropriate application characteristics and flowability of the gap filler composition can be secured.

[0048] In some embodiments, the weight average molecular weight of the first siloxane-based resin may be adjusted in consideration of the viscosity within the above-described range. For example, the weight average molecular weight of the first siloxane-based resin may be 1,500 to 50,000, 10,000 to 50,000, 10,000 to 30,000, or 10,000 to 25,000.

[0049] In chemical formula 1, n can be adjusted in consideration of the viscosity range. For example, n can be a natural number in the range of 40 to 800, 80 to 800, 100 to 800, 130 to 700, or 150 to 700.

[0050] The content of the first siloxane-based resin among the total weight of the gap filler composition (e.g., solid content) may be 1.5 wt% to 13 wt%. In one embodiment, the content of the first siloxane-based resin may be 5 wt% to 13 wt%, 7 wt% to 12 wt%, or 7.5 wt% to 10 wt%. Within the above content range, a gap filler having appropriate hardness and elasticity can be effectively formed.

[0051] The above second siloxane-based resin may be a siloxane-based resin having a different structure from the above first siloxane-based resin.

[0052] The above second siloxane resin is included as a chain extender or chain regulator of the gap filler composition, and can control the overall viscosity, flowability, crosslinking property, etc. of the composition.

[0053] According to exemplary embodiments, the second siloxane-based resin may be a siloxane-based resin in which a saturating group (e.g., a hydrogen atom) is bonded to silicon atoms at both terminals.

[0054] For example, the second siloxane resin may include a compound represented by the following chemical formula 2.

[0055] [Chemical Formula 2]

[0056]

[0057] In some embodiments, 25 of the second siloxane resin o At C, the viscosity can be from 10 cps to 1,500 cps, from 100 cps to 1,500 cps, from 200 cps to 1,500 cps, or from 300 cps to 1,200 cps.

[0058] The weight average molecular weight of the second siloxane-based resin can be adjusted according to the viscosity range. For example, the weight average molecular weight of the second siloxane-based resin can be 500 to 50,000, 10,000 to 50,000, 10,000 to 30,000, or 10,000 to 25,000. Within the molecular weight and viscosity ranges, the curing characteristics and curing speed described below can be more easily secured, and appropriate application characteristics and flowability of the gap filler composition can be secured.

[0059] In chemical formula 2, m can be adjusted in consideration of the molecular weight and viscosity ranges. For example, m can be a natural number in the range of 10 to 700, 20 to 700, 30 to 700, 50 to 700, 100 to 700, or 130 to 700.

[0060] The content of the second siloxane-based resin among the total weight of the gap filler composition (e.g., solid content) may be 0.5 wt% to 10 wt%. In one embodiment, the content of the second siloxane-based resin may be 2 wt% to 10 wt%, 2 wt% to 7 wt%, or 2 wt% to 5 wt%. Within the above content range, a gap filler having appropriate hardness and elasticity can be effectively formed.

[0061] According to exemplary embodiments, the content of the siloxane-based resin based on the total weight (e.g., solid content) of the gap filler composition may be from 2 wt% to 23 wt%. In one embodiment, the content of the siloxane-based resin may be from 7 wt% to 23 wt%, from 7 wt% to 20 wt%, from 10 wt% to 15 wt%, or from 10 wt% to 14 wt%.

[0062] In some embodiments, the gap filler composition may further include a crosslinking agent. The crosslinking agent may be a siloxane-based resin having relatively low viscosity and having methyl groups bonded to silicon atoms at both ends. For example, the crosslinking agent may include a compound represented by Chemical Formula 3.

[0063] [Chemical Formula 3]

[0064]

[0065] In one embodiment, the viscosity of the crosslinking agent may be less than the viscosity of the second siloxane-based resin. In one embodiment, the viscosity of the crosslinking agent may be 25 o In C, the viscosity can be less than 100 cps, and n in chemical formula 3 can be adjusted considering the above viscosity range.

[0066] A crosslinking agent may be included in the crosslinking composition described below. The content of the crosslinking agent in the total weight of the gap filler composition may be 0.1 wt% to 0.5 wt%.

[0067] The above catalyst can be used as a regulator for obtaining curing characteristics and curing speed described below by promoting crosslinking and / or interaction of the siloxane resin of the gap filler composition.

[0068] In some embodiments, the catalyst may comprise a compound or complex of Pt(II), Pt(IV), and / or Pt(0). For example, the catalyst may comprise chloroplatinic acid, Ashby's catalyst, or Karstedt catalyst.

[0069] According to exemplary embodiments, the catalyst may include an organic-inorganic hybrid catalyst containing platinum and silicon. In one embodiment, the platinum may be Pt(0) having an oxidation state of 0.

[0070] The catalyst may contain Pt atoms and Si2O groups (-Si-O-Si-) within the molecule. For example, silicon (Si) atoms of the Si2O group may be bonded to vinyl groups, and Pt atoms may be coordinated or captured by the vinyl groups.

[0071] According to exemplary embodiments, the weight ratio of platinum (Pt) to the weight of silicon (Si) atoms and oxygen atoms (O) in the catalyst may be 1.2 to 2.0, 1.2 to 1.5, or 1.25 to 1.45.

[0072] By using a catalyst having the above weight ratio range, appropriate catalyst activity through Pt atoms can be maintained. Accordingly, the curing characteristics and curing speed of the gap filler composition described below can be easily achieved using the catalyst.

[0073] For example, the catalyst may include a unit represented by the following chemical formula 4 within the molecule.

[0074] [Chemical Formula 4]

[0075] Ptㆍ[(CH2=CH(CH3)2Si)O]

[0076] In some embodiments, the content of the catalyst may be 0.01 wt% to 0.05 wt% of the total weight of the composition. Within this range, an appropriate curing speed can be achieved while preventing excessive hardness / elasticity increase of the gap filler.

[0077] The above filler may be included as a component that increases the thermal conductivity of the gap filler and thus improves the heat dissipation characteristics of the battery pack.

[0078] The above filler may include thermally conductive inorganic particles. Examples of the thermally conductive inorganic particles include aluminum hydroxide (Al(OH)3), magnesium hydroxide (Mg(OH)2), calcium hydroxide (Ca(OH)2), hydromagnesite (Mg5(CO3)4(OH)2·4H2O), magnesia, alumina, aluminum nitride (AlN), boron nitride (BN), silicon nitride, SiC, ZnO, BeO, etc.

[0079] According to exemplary embodiments, the filler may include aluminum hydroxide (Al(OH)3) particles. The aluminum hydroxide particles have a relatively low specific gravity compared to alumina particles, and can lower the overall specific gravity of the gap filler composition and improve filling properties and flowability.

[0080] In some embodiments, the gap filler composition may not include alumina particles. In one embodiment, the thermally conductive inorganic particles may consist essentially of aluminum hydroxide particles.

[0081] In some embodiments, the thermally conductive inorganic particles or aluminum hydroxide particles may be non-surface-treated particles. For example, the thermally conductive inorganic particles or aluminum hydroxide particles may be bare particles that have not been surface-treated with an alkyl group or an alkylsilane group. Therefore, the specific gravity reduction effect resulting from the use of the aluminum hydroxide particles can be more effectively implemented. For example, the thermally conductive inorganic particles may not be surface-treated with an alkylsilane agent such as hexyltrimethoxysilane.

[0082] The above thermally conductive inorganic particles can be included in the largest amount (weight %) in the gap filler composition. Therefore, the thermal conductivity properties of the gap filler composition can be sufficiently increased.

[0083] The content of the thermally conductive inorganic particles in the total weight of the composition may be 70 wt% to 95 wt%, or 75 wt% to 95 wt%. In some embodiments, the content of the thermally conductive inorganic particles may be 75 wt% to 90 wt%, or 80 wt% to 90 wt%, or 82 wt% to 88 wt%.

[0084] According to exemplary embodiments, the filler may further include hollow particles. The hollow particles may be added to further reduce the specific gravity of the gap filler composition while maintaining or increasing thermal conductivity.

[0085] Examples of the hollow particles include hollow organic particles such as acrylic particles such as PMMA (poly(methylmethacrylate)), epoxy particles, nylon particles, styrene particles, styrene / vinyl copolymer particles, and the like; or hollow inorganic particles such as silica particles, indium oxide particles, tin oxide particles, zirconium oxide particles, zinc oxide particles, and titania particles.

[0086] According to exemplary embodiments, the crush strength of the hollow particles may be greater than or equal to 1,000 psi. In some embodiments, the crush strength of the hollow particles may be from 1,000 psi to 100,000 psi, from 1,500 psi to 60,000 psi, or from 2,000 psi to 50,000 psi. The crush strength may be an isostatic crush strength.

[0087] Within the above range, the external impact resistance of a gap filler formed using the gap filler composition can be enhanced. If the crushing strength of the hollow particles is less than 1,000 psi, some of the hollow particles may be destroyed, resulting in uncured or increased specific gravity of the gap filler composition. If the crushing strength of the hollow particles exceeds the above range, the specific gravity of the gap filler composition may increase due to an increase in the density of the hollow particles.

[0088] In one embodiment, hollow inorganic particles may be used as the hollow particles, for example, hollow silica particles may be used.

[0089] In one embodiment, particles having a density in the range of 0.05 g / cc to 0.8 g / cc may be used as the hollow particles. Within this range, the effect of reducing specific gravity through the use of the hollow particles can be sufficiently achieved. The density of the hollow particles may be 0.1 g / cc to 0.8 g / cc, 0.1 g / cc to 0.5 g / cc, or 0.2 g / cc to 0.4 g / cc.

[0090] In one embodiment, the average particle diameter (D50) of the hollow particles may be 0.01 μm to 100 μm. The average particle diameter (D50) of the hollow particles may be adjusted depending on the particle size of the thermally conductive inorganic particles and the graphite particles. The average particle diameter (D50) of the hollow particles may be 1 μm to 70 μm, or 2 μm to 60 μm.

[0091] In some embodiments, the content of the hollow particles may be 0.1 wt% to 5 wt%, 0.5 wt% to 5 wt%, 1 wt% to 5 wt%, or 1 wt% to 4 wt% of the total weight of the composition. Within this range, the specific gravity of the gap filler composition can be effectively reduced without excessively lowering the thermal conductivity of the composition.

[0092] The above filler may include graphite particles. The inclusion of the graphite particles may improve thermal conductivity while maintaining a reduced specific gravity of the gap filler composition.

[0093] Examples of the above graphite particles include natural graphite, artificial graphite, activated carbon, carbon black, fullerene, carbon nanotubes, and graphene oxide.

[0094] According to exemplary embodiments, natural graphite may be used as the graphite particles. The natural graphite may include spheroidal graphite, expanded graphite, and / or spheroidal graphite.

[0095] In some embodiments, spherical graphite may be used as the graphite particles. The average particle size of the spherical graphite may be from 0.1 μm to 50 μm, or from 1 μm to 30 μm.

[0096] By including spherical graphite as graphite particles, the thermal conductivity of the gap filler composition can be increased while improving the viscosity change rate, and thus the storage stability of the gap filler composition can be improved.

[0097] In one embodiment, the sphericity of the graphite particles may be from 0.5 to 0.95. In one embodiment, the sphericity of the graphite particles may be from 0.7 to 0.95.

[0098] The above sphericity may be a value calculated according to the following equation 1.

[0099] Equation 1: Degree of sphericity (D s ) = l x / l y

[0100] In the above equation 1, l x is the average of the major axis lengths of 10 to 30 particles included in the SEM images of graphite particles, and l y is the average of the short axis lengths of 10 to 30 particles included in the SEM images of graphite particles.

[0101] Above lx and l y Each SEM image may be an average of 10 to 30 particles. In addition, the SEM image may be an average of values ​​measured from one or more images. For example, the average value of 10 to 30 particles included in one SEM image may be measured, the average value of 10 to 30 particles included in another SEM image may be measured, and then the average value of the two values ​​may be derived.

[0102] Above l x is the longest axis value of one particle in the SEM image, and l y is the shortest axis value of the particle that is identical to the particle whose major axis value was measured.

[0103] The thermal conductivity of the gap filler composition can be significantly improved within the above sphericity range. If the sphericity is lower than the above sphericity, the thermal conductivity may not be improved and the viscosity may decrease, and if the sphericity is higher than the above sphericity, the production yield of the gap filler composition may be reduced.

[0104] In one embodiment, the content of the graphite particles may be 0.5 wt% to 16 wt% of the total weight of the composition. The content of the graphite particles may be 1 wt% to 16 wt%, 1 wt% to 12 wt%, or 1 wt% to 8 wt%. Within the above range, the thermal conductivity of the gap filler composition can be effectively increased without excessively increasing the viscosity of the composition.

[0105] The gap filler composition according to exemplary embodiments may further comprise an amino-silicone based dispersant.

[0106] In some embodiments, the amino-silicone dispersant may comprise an amino silicone oil comprising siloxane units and amino groups.

[0107] For example, the amino-silicone dispersant may include a siloxane unit represented by the following general formula 1 and an amino-containing group represented by the following general formula 2. The amino-containing group may be bonded to a silicon atom.

[0108] [General Formula 1]

[0109]

[0110] In general formula 1, R a and R b Each can be hydrogen, a C1-C5 alkyl group, or any one of the groups represented by the general formula 2.

[0111] [General Formula 2]

[0112] -ALK1-NH-ALK2-NH-R c

[0113] General formula 1, R c may be hydrogen or a C1-C5 alkyl group. ALK1 and ALK2 may each independently be a C1-C6 alkylene group.

[0114] For example, a siloxane unit represented by the general formula 1 may be included as a repeating unit of the amino-silicone dispersant. R of at least one siloxane unit among the siloxane units in which an amino-containing group represented by the general formula 2 is repeated a or R b can be combined as

[0115] In one embodiment, the amino-silicone-based dispersant may include a terminal amine group (-NH2). The inclusion of an amine group at the terminal of the amino-silicone-based dispersant may enhance the dispersibility of aluminum hydroxide.

[0116] By including the amino-silicone-based dispersant, sufficient dispersibility can be secured even when non-surface-treated thermally conductive inorganic particles are used. Accordingly, uniform thermal conductivity can be achieved throughout the gap filler while reducing the composition's specific gravity.

[0117] Additionally, a dispersant containing a siloxane unit can be used to stabilize the filler at the interface between the siloxane-based resin and the filler described above. Accordingly, agglomeration of the filler can be prevented, the viscosity of the composition can be stably maintained, and flowability can be improved.

[0118] In some embodiments, a dispersant containing a hydroxyl group or an epoxy group may not be used as the dispersant. Accordingly, side reactions with the filler and siloxane-based resin due to the hydroxyl group or epoxy group can be prevented, and the composition dispersibility and thermal conductivity uniformity can be improved.

[0119] In some embodiments, the content of the amino-silicone-based dispersant may be 0.1 wt% to 3 wt% of the total weight of the composition. In one embodiment, the content of the amino-silicone-based dispersant may be 0.1 wt% to 0.5 wt%, or 0.2 wt% to 0.4 wt%. Within the above range, the dispersibility of the aluminum hydroxide particles can be improved and an increase in the specific gravity of the composition can be prevented.

[0120] In some embodiments, the amine value, defined as the amount of 0.1 N HCl titrant required to neutralize 10 g of the amino-silicone-based dispersant, may be 1 mgKOH / g to 80 mgKOH / g, 10 mgKOH / g to 60 mgKOH / g, or 20 mgKOH / g to 50 mgKOH / g. Within this range, the filler stabilization effect described above can be effectively implemented.

[0121] In some embodiments, the gap filler composition may further include additives to enhance the conductivity and curability of the composition within a range that does not inhibit the actions of the siloxane-based resin, the catalyst, and the filler described above. For example, the additives may include flame retardants, surfactants, silane coupling agents, colorants (e.g., pigments), antioxidants, plasticizers, and the like. The additives may be included in the composition as a remainder or extra amount, excluding the siloxane-based resin, catalyst, and filler described above.

[0122] For example, examples of the flame retardant include organic flame retardants such as melamine cyanurate, and inorganic flame retardants such as magnesium hydroxide. In one embodiment, a liquid type flame retardant material (such as triethyl phosphate (TEP) or tris(1,3-chloro-2-propyl)phosphate (TCPP)) may be used.

[0123] For example, examples of the surfactant include polyethylene glycol, polypropylene glycol, oleic acid ethoxylate, alkylphenol ethoxylate, copolymers of ethylene oxide and propylene oxide, and silicone polymers.

[0124] Examples of the above silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, 3-mercaptopropyl trimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, 3-isocyanatepropyltriethoxysilane, γ-acetoacetatepropyltrimethoxysilane, etc.

[0125] As the above antioxidants, phenol compounds, quinone compounds, amine compounds, phosphorus compounds, phosphite compounds, thioether compounds, etc. can be used.

[0126] Examples of the above plasticizers include tetraethylene glycol monobutyl ether (3,6,9,12-tetraoxahexadecanol), triethylene glycol monobutyl ether (3,6,9-trioxatridecanol), diethylene glycol monobutyl ether (2-(2-butoxyethoxy)ethanol), propylene glycol monobutyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether (1-methoxy-2-propanol), propylene glycol monomethyl ether acetate, polyethylene glycol, and glycerin.

[0127] In exemplary embodiments, the specific gravity of the gap filler composition may be less than 3, or less than 2.5. In some embodiments, the specific gravity of the gap filler composition may be from 1.5 to 2, or from 1.5 to 1.9.

[0128] The above specific gravity is 4 under 1 atm. o C is a numerical value measured as a relative ratio of the density of water to a standard.

[0129] A gap filler having improved mechanical stability can be manufactured without increasing the weight of the battery pack within the above specific gravity range.

[0130] In exemplary embodiments, the viscosity of the gap filler composition may be 1,000 Pa·s or less, 850 Pa·s or less, or 200 Pa·s or more and 750 Pa·s or less. The viscosity may be 25 o It may be a value measured in C.

[0131] The stability of the gap filler composition is secured within the above viscosity range, enabling long-term storage.

[0132] The gap filler composition may be prepared as a two-component composition. For example, the gap filler composition may be prepared by separately preparing a main composition and a crosslinking composition, and then mixing the main composition and the crosslinking composition.

[0133] According to embodiments of the present invention, the above-described first siloxane resin may be commonly included in the subject composition and the crosslinking composition.

[0134] According to exemplary embodiments, the gap filler composition may be prepared as a two-component composition. For example, the gap filler composition may be prepared by separately preparing a main composition and a crosslinking composition, and then mixing the main composition and the crosslinking composition.

[0135] The above-mentioned subject composition may include the first siloxane-based resin, the catalyst, and the filler. The above-mentioned crosslinking composition may include the second siloxane-based resin, the crosslinking agent, and the filler.

[0136] For example, the second siloxane-based resin may be mixed with the first siloxane-based resin in the above-described subject composition while the catalyst is distributed therein. Accordingly, since the second siloxane-based resin is introduced while the crosslinking points are distributed within the subject composition, curing efficiency may be enhanced.

[0137] In some embodiments, the first siloxane-based resin may also be included in the crosslinking composition. The weight of the first siloxane-based resin included in the subject composition may be greater than the weight of the first siloxane-based resin included in the crosslinking composition.

[0138] The filler may be divided and included in the main composition and the crosslinking composition. In one embodiment, the ratio of the amount of the filler included in the main composition to the amount of the filler included in the crosslinking composition may be 0.8 to 1.2, or 0.85 to 1.15. Within the above ratio range, the heat conduction efficiency can be enhanced through uniform distribution of the filler.

[0139] As described above, the filler includes thermally conductive inorganic particles, hollow particles, and graphite particles, and an amino-silicon-based dispersant may be used to improve the dispersibility of the unsurfaced particles. The amino-silicon-based dispersant may also be separately included in the main composition and the crosslinking composition.

[0140] Battery Pack

[0141] FIG. 1 is a schematic cross-sectional view illustrating a battery pack according to exemplary embodiments.

[0142] Referring to FIG. 1, a battery pack (100) includes a battery module (110) and a support plate (130), and may include a gap filler (120) formed on the battery module (110) and the support plate (130).

[0143] The battery module (110) may include a plurality of battery cells (112). Each of the battery cells (112) may include an electrode assembly including a positive electrode and a negative electrode alternately and repeatedly stacked. The positive electrode and the negative electrode may be alternately and repeatedly stacked with a separator interposed therebetween. The positive electrode includes lithium metal oxide as a positive electrode active material, and the battery cell (112) may be provided as a lithium secondary battery.

[0144] A plurality of battery cells (112) each include a positive lead and a negative lead, and the positive leads and the negative leads can be joined to each other via a bus bar to define a battery module (110).

[0145] The battery module (110) can be fixed on the support plate (130). A gap filler composition according to the above-described embodiments can be applied and cured between the battery module (110) and the support plate (130) to form a gap filler (120).

[0146] The battery module (110) can be stably fixed on the support plate (130) by the gap filler (120). As described above, the gap filler (120) has stable curing characteristics and can have improved thermal conductivity characteristics.

[0147] According to exemplary embodiments, the gap filler composition has a low specific gravity and can maintain a target hardness range over a predetermined time period. Therefore, stable hardness characteristics can be maintained without compromising the overall electric vehicle process efficiency or increasing the weight of the battery pack.

[0148] Therefore, it has impact resistance and heat resistance for protecting the battery module (110) even under high temperature conditions, and can provide sufficient heat dissipation characteristics.

[0149] The gap filler (120) may be provided as a thermally conductive layer. For example, the thermal conductivity of the gap filler (120) may be about 2.0 W / m·K or more. In one embodiment, the thermal conductivity of the gap filler (120) may be 2.20 W / m·K to 6.0 W / m·K, 2.20 W / m·K to 6.0 W / m·K, or 2.40 W / m·K to 5.0 W / m·K.

[0150] The above thermal conductivity can be measured by a measuring device and method according to ISO 22007-2 standard.

[0151] In the above thermal conductivity range, heat generated during the charging / discharging process of the battery pack can be quickly transferred to the outside, thereby improving the thermal stability of the battery pack.

[0152] According to exemplary embodiments, the height of the gap filler (120) on which the battery module (110) is mounted may be 5.4 mm to 5.8 mm, or 5.4 mm to 5.7 mm. Within the above range, sufficient support stability for the battery module (110) is provided, and sufficient thermal conductivity characteristics can be realized. In addition, the occurrence of a gap between the battery module (110) and the gap filler (120) due to excessive curing can be prevented.

[0153] Hereinafter, experimental examples including specific examples and comparative examples are presented to help understand the present invention, but these are only illustrative of the present invention and do not limit the scope of the appended claims. It is obvious to those skilled in the art that various changes and modifications to the examples are possible within the scope and technical idea of ​​the present invention, and it is natural that such changes and modifications fall within the scope of the appended claims.

[0154] Examples and Comparative Examples

[0155] A gap filler composition was prepared according to the ingredients and contents (parts by weight) described in Table 1 below.

[0156] Specifically, the subject composition included a first siloxane-based resin (vinyl-terminated siloxane resin) and a catalyst, and the crosslinking composition included a first siloxane-based resin (vinyl-terminated siloxane resin) and a second siloxane-based resin (hydrogen-terminated siloxane resin). The first siloxane-based resin was divided and included in the subject composition and the crosslinking composition at a weight ratio of about 2:1. The crosslinking composition further included a crosslinking agent having a hydrogen-terminated siloxane resin structure.

[0157] Thermally conductive inorganic particles, hollow particles, graphite particles and amino-silicon dispersants were each divided and included in the main composition and the crosslinking composition at a weight ratio of 1:1.

[0158] The subject composition and the crosslinking composition were prepared by including the components of Table 1 as described above, placing them in a paste mixer, mixing and stirring them at 600 rpm / 500 rpm for 3 minutes, and then defoaming them in a vacuum at 1000 rpm / 100 rpm for 10 minutes.

[0159] The crushing strength of the hollow particles and the sphericity of the graphite particles included in the above-mentioned subject composition and crosslinking composition are as shown in Table 2. Table 2 below shows examples having the same contents of resin, catalyst, etc. as Example 1, and examples having different crushing strengths of the hollow particles and different sphericity of the graphite particles.

[0160] Classification 1 Siloxane resin (A-1) 2 Siloxane resin (B-1) Crosslinking agent (C-1) Dispersant (D-1) Thermally conductive inorganic particles (E-1) Hollow particles (F-1) Graphite Particle (G-1) Catalyst (H-1) Example 18.034.000.200.2485.001.501.000.03 Example 28.034.000.200.2486.000.501.000.03 Example 38.034.000.200.2484.002.501.000.03 Example 48.034.000.200.2481.505.001.000.03 Example 58.034.000.200.2484.001.502.000.03 Example 68.034.000.200.2482.001.5 04.000.03Example 78.034.000.200.2478.001.508.000.03Example 88.034.000.200.2474.001.5012.000.03Example 98.034.000.200.2470.001.5016.000.03Comparative Example 19.054.480.200.2485.00-1.000.03Comparative Example 29.054.480.200.2485.001.50-0.03Comparative Example 38.034.000.200.2485.001.501.000.03

[0161] The specific ingredients listed in Table 1 are as follows.

[0162] A-1) First siloxane resin

[0163] Polydimethylsiloxane resin with a viscosity of 270 cps and vinyl groups at both ends (see Chemical Formula 1)

[0164] B-1) Second siloxane resin

[0165] Polydimethylsiloxane resin with a viscosity of 500 cps and hydrogenated at both ends (see Chemical Formula 2)

[0166] C-1) Crosslinking agent

[0167] Polydimethylsiloxane resin hydrogenated at both ends with a viscosity of 65 cps (see Chemical Formula 3)

[0168] D-1) Amino-silicone dispersant (see general formulas 1 and 2): amine value 36 mgKOH / g

[0169] E-1) Thermally conductive inorganic particles

[0170] Aluminum hydroxide particles (D50: 5 μm)

[0171] F-1) Hollow silica particles

[0172] Density 0.35 g / cc, Isostatic Crush Strength: 2,000 psi

[0173] G-1) Graphite particles

[0174] Natural spherical graphite (D50: 15㎛, sphericity 0.80 according to Equation 1 below)

[0175] H-1) Catalyst

[0176] Catalyst: Pt / Si2O combined catalyst (Pt / (Si+O) weight ratio: 1.35)

[0177] Classification Hollow particle crushing strength (psi) Graphite particle sphericity Example 1-14,000 0.80 Example 1-28,000 Example 1-316,000 Example 1-41,000 Example 1-580,000 Example 1-62,000 0.01 Example 1-70.40 Example 1-80.50 Example 1-90.95 Example 1-100.97 Comparative Example 3500 0.80

[0178] The hollow particle crushing strength in Table 2 is the isostatic crushing strength, and the graphite particle sphericity is the value of the major axis length of the particle compared to the minor axis length of the particle in the image measured by SEM (see Equation 1 below).

[0179] Equation 1: Degree of sphericity (D s ) = l x / l y (l x is the major axis length of the particle, and l y is the short-axis length of the particle)

[0180] Experimental example

[0181] (1) Specific gravity measurement

[0182] The subject composition and crosslinking composition of the examples and comparative examples were mixed at a mass ratio of 1:1 using a two-component cartridge to prepare a gap filler composition. The specific gravity of the gap filler composition was measured according to Test Method A of ASTM D792.

[0183] Specifically, the weight of each composition and the weight of the composition in water were measured according to the above specifications, and the specific gravity was calculated through the difference in the measured weights.

[0184] (2) Thermal conductivity measurement

[0185] The subject composition and crosslinking composition of the examples and comparative examples were mixed at a mass ratio of 1:1 using a two-component cartridge and cured to form a resin layer.

[0186] The thermal conductivity of the above resin layer was measured using a hot disk measuring device according to the ISO 22007-2 standard. Specifically, a numerical layer measuring 20 mm in length and width and 6.0 mm in thickness was formed, and the average value was calculated after a total of three measurements.

[0187] (3) Viscosity measurement

[0188] The subject composition and crosslinking composition of the examples and comparative examples were mixed at a mass ratio of 1:1 using a two-component cartridge to prepare a gap filler composition. The viscosity of the gap filler composition over time was measured using a viscoelasticity measuring instrument (Advanced Rheometic Expansion System) (Brookfield, DV2T Rheometer). (Measurement conditions: 20 rpm / 25°C, Gap 5 mm).

[0189] The evaluation results are shown in Table 3 below.

[0190] ClassificationSpecific gravityThermal conductivity(W / m·K)Viscosity(Pa·s)Example 11.852.50450Example 1-11.852.50452Example 1-21.852.50454Example 1-31.852.50455Example 1-42.002.20648Example 1-52.052.50452Example 1-61.852.20740Example 1-71.852.28600Example 1-81.852.50500Example 1-91.852.60430Example 1-101.852.60432Example 22.152.50406Example 31.802.50432 Example 41.601.80593 Example 51.852.70492 Example 61.853.30570 Example 71.853.80656 Example 81.854.00750 Example 91.854.501,252 Comparative Example 12.002.50350 Comparative Example 21.852.20580 Comparative Example 32.102.00800

[0191] Referring to Tables 1 and 2, examples including thermally conductive inorganic particles, hollow particles and graphite particles provided stable viscosity stability while maintaining a low specific gravity of 3.0 or less, or less than 2.00 and 1.5 or more; and a thermal conductivity of 2.20 W / m·K or more, or in the range of 2.50 W / m·K to 4.50 W / m·K.

[0192] In Examples 1-4, where the hollow particle crushing strength was relatively low, some of the hollow particles were destroyed, resulting in a somewhat higher specific gravity, a lower thermal conductivity, and a somewhat higher viscosity compared to other examples. In Examples 1-5, where the hollow particle crushing strength was relatively high, the density of the hollow particles increased, resulting in a somewhat higher specific gravity compared to other examples.

[0193] In Examples 1-6 and 1-7, where the degree of sphericity of the graphite particles was relatively low, the thermal conductivity was lower and the viscosity was higher compared to other examples.

[0194] In the case of Examples 1-10, in which the degree of sphericity of the graphite particles was relatively high, the specific gravity, thermal conductivity, and viscosity were within the above-described ranges, but the manufacturing efficiency decreased, resulting in a decrease in the amount of the manufactured gap filler composition.

[0195] In Example 2, where the content of hollow particles was relatively low, the specific gravity was relatively high compared to other examples, and in Example 4, where the content of hollow particles was relatively high, the specific gravity was low compared to other examples, but the thermal conductivity was low.

[0196] In Example 9, where the content of graphite particles was relatively high, the flowability of the composition was reduced, and a relatively high viscosity was confirmed compared to other examples.

[0197] In the case of Comparative Example 1, which does not include hollow particles, the specific gravity increased compared to the examples including hollow particles.

[0198] In the case of Comparative Example 2, which does not include graphite particles, the thermal conductivity was significantly reduced compared to the examples including graphite particles.

[0199] In Comparative Example 3, where the fracture strength of the hollow particles was less than 1,000 psi, the specific gravity of the composition increased even when the hollow particles were included, and it was confirmed that the specific gravity was actually higher than when the hollow particles were not included. In addition, the thermal conductivity was found to be lower than when the hollow particles were not included.

Claims

1. Siloxane resin; Filler comprising thermally conductive inorganic particles, hollow particles and graphite particles; and Containing a catalyst, A gap filler composition wherein the crushing strength of the hollow particles is greater than or equal to 1,000 psi.

2. A gap filler composition according to claim 1, wherein the hollow particles have a crushing strength of 2,000 psi to 60,000 psi.

3. A gap filler composition according to claim 1, wherein the hollow particles include hollow silica particles.

4. A gap filler composition according to claim 1, wherein the content of the hollow particles is 1 wt% to 5 wt% of the total weight of the composition.

5. A gap filler composition according to claim 1, wherein the graphite particles include spherical graphite.

6. In claim 1, a gap filler composition wherein the sphericity of the graphite particles according to the following formula 1 is 0.5 to 0.95: [Formula 1] Spherical shape(D) s ) = l x / l y (In the above equation 1, l x is the average of the major axis lengths of 10 to 30 particles included in the SEM images of graphite particles, and l y is the average of the short axis lengths of 10 to 30 particles included in the SEM images of graphite particles.

7. A gap filler composition according to claim 1, wherein the content of the graphite particles is 1 wt% to 12 wt% of the total weight of the composition.

8. A gap filler composition according to claim 1, wherein the content of the thermally conductive inorganic particles is 75 wt% to 95 wt% of the total weight of the composition.

9. A gap filler composition according to claim 1, further comprising an amino-silicon-based dispersant, wherein the content of the amino-silicon-based dispersant is 0.1 wt% to 3 wt% of the total weight of the composition.

10. A gap filler composition according to claim 1, wherein the siloxane-based resin comprises a first siloxane-based resin including an unsaturated terminal group and a second siloxane-based resin including a saturated terminal group.

11. A gap filler composition according to claim 10, wherein the siloxane-based resin further comprises a crosslinking agent including a siloxane-based resin having methyl groups bonded to silicon atoms at both terminals.

12. A gap filler composition having a specific gravity of less than 2 according to claim 1.

13. A gap filler composition according to claim 1, having a viscosity of 750 Paㆍs or less at 25°C.

14. Multiple battery modules; Support plate; and A battery pack comprising a gap filler formed using the gap filler composition of claim 1 between the battery modules and the support plate.

Images