KR102832948B1 - Gap filler composition and battery pack - Google Patents

Abstract

A gap filler composition according to embodiments of the present invention includes a siloxane-based resin, a filler including alumina particles, aluminum hydroxide particles, and boron nitride particles, and a catalyst. The content of the filler is 82 wt% or more and less than 89 wt% of the total weight of the composition. Of the total weight of the filler, the content of the alumina particles is 30 wt% to 40 wt%, the content of the aluminum hydroxide particles is 35 wt% to 60 wt%, and the content of the boron nitride particles is 2 wt% to 25 wt%.

Description

Gap filler composition and battery pack {GAP FILLER COMPOSITION AND BATTERY PACK}

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

Secondary batteries are batteries that can be repeatedly charged and discharged, and are widely used as power sources for portable electronic devices such as mobile phones and laptop PCs. For example, lithium secondary batteries have high operating voltage, energy density, and rate characteristics, and have recently been used as power sources for electric vehicles.

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.

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.

The above gap filler composition application process can be included in the entire electric vehicle production platform. Therefore, a gap filler composition that is cured within a predetermined time period and provides desired properties may be required to maintain automotive process efficiency/reliability.

In addition, there is a need to design a composition capable of forming 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.

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 specific properties and composition of the gap filler.

Korean Patent Publication No. 10-2402503

An object of the present invention is to provide a gap filler composition providing improved thermal properties and mechanical properties.

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

1. A siloxane-based resin; a filler including alumina particles, aluminum hydroxide particles and boron nitride particles; and a catalyst.

The content of the filler in the total weight of the composition is 82 wt% or more and less than 89 wt%,

A gap filler composition, wherein, among the total weight of the filler, the content of the alumina particles is 20 wt% to 40 wt%, the content of the aluminum hydroxide particles is 40 wt% to 70 wt%, and the content of the boron nitride particles is 2 wt% to 30 wt%.

2. A gap filler composition according to 1 above, wherein the alumina particles include first alumina particles having an average particle diameter of 50 μm or more.

3. A gap filler composition in the above 2, wherein the alumina particles further include second alumina particles having an average particle diameter (D50) in a range of 15 ㎛ to 30 ㎛, and third alumina particles having an average particle diameter (D50) of less than 15 ㎛.

4. A gap filler composition in the above 3, wherein the content of the first alumina particles among the total weight of the alumina particles is 50 wt% or more.

5. A gap filler composition according to the above 1, wherein the aluminum hydroxide particles include first aluminum hydroxide particles having an average particle diameter (D50) in the range of 45 μm to 90 μm.

6. A gap filler composition according to the above 5, wherein the aluminum hydroxide particles further include second aluminum hydroxide particles having an average particle diameter (D50) in a range of 20 ㎛ to 35 ㎛, and third aluminum hydroxide particles having an average particle diameter (D50) of less than 15 ㎛.

7. A gap filler composition according to 6 above, wherein the content of the first aluminum hydroxide particles is 50 wt% or more of the total weight of the aluminum hydroxide particles.

8. A gap filler composition in the above 1, wherein the average particle diameter (D50) of the boron nitride particles is in the range of 20 ㎛ to 40 ㎛.

9. In the above 1, the gap filler composition includes particles each surface-treated with a silane agent, the alumina particles and the boron nitride particles.

10. A gap filler composition in the above 9, wherein the aluminum hydroxide particles are particles not treated with a silane agent.

11. A gap filler composition in the above 1, wherein the siloxane-based resin includes a low ^- viscosity siloxane-based resin having a viscosity in the range of 200 cps to 400 cps at 25 ^o C, a medium-viscosity siloxane-based resin having a viscosity in the range of 800 cps to 1,200 cps at 25 ^o C, and a high-viscosity siloxane-based resin having a viscosity in the range of 18,000 cps to 22,000 cps at 25 o C.

12. A gap filler composition in the above 11, wherein the low viscosity siloxane resin, the medium viscosity siloxane resin and the high viscosity siloxane resin are each a siloxane resin containing a crosslinkable terminal group.

13. A gap filler composition according to 12 above, wherein the siloxane-based resin further comprises a siloxane resin containing a non-crosslinkable terminal group.

14. A gap filler composition according to 13 above, wherein the non-crosslinkable terminal group-containing siloxane resin comprises a first non-crosslinkable terminal group-containing siloxane resin in which both terminals are capped with hydrogen (H) and a second non-crosslinkable terminal group-containing siloxane resin in which both terminals are capped with methyl groups (-CH ₃ ).

15. 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.

A gap filler composition according to exemplary embodiments of the present invention may include alumina particles, boron nitride (BN) particles, and aluminum hydroxide particles. By using the boron nitride (BN) particles and aluminum hydroxide particles together with the alumina particles in a predetermined content ratio range, the specific gravity of the gap filler composition can be reduced while maintaining the thermal conductivity of the gap filler.

Accordingly, the gap filler composition can be applied to a vehicle battery pack to reduce the weight of the battery pack while promoting rapid heat dissipation even when the temperature increases due to repeated charging/discharging of the battery pack.

The gap filler composition according to embodiments of the present invention may include a plurality of siloxane-based resins having different viscosity ranges. Accordingly, the curing speed of the gap filler composition can be increased and the target hardness can be secured within a predetermined time range.

FIG. 1 is a schematic perspective view illustrating a battery pack according to exemplary embodiments.

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 is provided. In addition, according to embodiments of the present invention, a battery pack using the gap filler composition is provided.

<Gap filler composition>

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

The above siloxane-based resin may be provided as a base component that provides curability of the gap filler composition. According to exemplary embodiments, the siloxane-based resin may include a siloxane resin containing a crosslinkable terminal group.

According to exemplary embodiments, the crosslinkable terminal group-containing siloxane resin may be a siloxane-based resin having vinyl groups bonded to both terminals of the molecule.

For example, the crosslinkable terminal group-containing siloxane resin may include a compound represented by the following chemical formula 1.

[Chemical Formula 1]

In some embodiments, the weight average molecular weight of the first siloxane resin may be from 10,000 to 50,000, preferably from 10,000 to 30,000, more preferably from 10,000 to 25,000.

According to exemplary embodiments, the first siloxane resin may include a plurality of resins having different viscosity ranges.

According to embodiments of the present invention, the crosslinkable terminal group-containing siloxane resin may include a low viscosity siloxane resin, a medium viscosity siloxane resin, and a high viscosity siloxane resin, the viscosities of which sequentially increase.

In some embodiments, the viscosity (viscosity at 25 ^o C) of the low viscosity siloxane resin can be from 200 cps to 400 cps, preferably from 200 cps to 300 cps, more preferably from 250 cps to 300 cps.

The viscosity (viscosity at 25 ^o C) of the above intermediate viscosity siloxane resin may be 800 cps to 1,200 cps, preferably 900 cps to 1,100 cps, more preferably 950 cps to 1,050 cps.

The viscosity (viscosity at 25 ^o C) of the above high viscosity siloxane resin may be 18,000 cps to 22,000 cps, preferably 19,000 cps to 21,000 cps, and more preferably 19,500 cps to 20,500 cps.

In some embodiments, the content of the low viscosity siloxane resin may be 0.5 wt% to 2 wt%, the content of the medium viscosity siloxane resin may be 70 wt% to 90 wt%, and the content of the high viscosity siloxane resin may be 10 wt% to 20 wt%, of the total weight of the crosslinkable terminal group-containing siloxane resin.

Preferably, among the total weight of the crosslinkable terminal group-containing siloxane resin, the content of the low viscosity siloxane resin may be 0.5 wt% to 1.5 wt%, the content of the medium viscosity siloxane resin may be 80 wt% to 90 wt%, and the content of the high viscosity siloxane resin may be 10 wt% to 15 wt%.

As described above, a plurality of crosslinkable siloxane resins having different viscosity ranges can be combined and used. Accordingly, the curing speed of the gap filler composition can be promoted while maintaining the dispersibility and flowability of the resin. Accordingly, a predetermined desired target hardness can be secured within a limited process time, and thermal stability can be quickly obtained.

For example, the base resin matrix and crosslinking points can be formed through the above-mentioned intermediate viscosity siloxane resin, and the curing speed and mechanical strength can be improved together by adding low viscosity and high viscosity siloxane resins.

In chemical formula 1, n can be adjusted in consideration of the molecular weight and viscosity range. For example, n is a natural number greater than or equal to 100, and can be a natural number in the range of, for example, 130 to 700, or 200 to 300.

The content of the crosslinkable terminal siloxane resin among the total weight of the gap filler composition (e.g., solid content) may be 10 wt% to 20 wt%, preferably 11 wt% to 20 wt%, more preferably 12 wt% to 20 wt%, or 14 wt% to 20 wt%. Within the above content range, a gap filler having appropriate hardness and elasticity can be effectively formed.

In some embodiments, the siloxane-based resin may further include a non-crosslinkable terminal group-containing siloxane resin. For example, the non-crosslinkable terminal group-containing siloxane resin may be a siloxane-based resin that does not include a crosslinkable group at a terminal.

In one embodiment, both terminals in the chain length direction of the non-crosslinkable terminal group-containing siloxane resin may be capped with hydrogen (H). In one embodiment, both terminals in the chain length direction of the non-crosslinkable terminal group-containing siloxane resin may be capped with an alkyl group (e.g., a methyl group (-CH ₃ )).

The non-crosslinkable terminal group-containing siloxane resin may be included as a chain extender or chain regulator in the gap filler composition, and may control the overall viscosity, flowability, crosslinkability, etc. of the composition. In addition, the non-crosslinkable terminal group-containing siloxane resin may be used as an auxiliary siloxane resin that controls the curing speed of the gap filler composition.

In some embodiments, the non-crosslinkable terminal group-containing siloxane resin may include a first non-crosslinkable terminal group-containing siloxane resin in which both terminals in the chain length direction are capped with hydrogen (H) and a second non-crosslinkable terminal group-containing siloxane resin in which both terminals in the chain length direction are capped with methyl groups (-CH ₃ ).

The above first non-crosslinkable terminal group-containing siloxane resin can be represented by the following chemical formula 2.

[Chemical formula 2]

For example, in chemical formula 2, m and n may each be a natural number in the range of 10 to 30. Preferably, m and n may each be a natural number in the range of 10 to 25, or in the range of 10 to 20.

The above second non-crosslinkable terminal group-containing siloxane resin can be represented by the following chemical formula 3.

[Chemical Formula 3]

For example, in chemical formula 3, m and n may each be a natural number in the range of 50 to 90. Preferably, m and n may each be a natural number in the range of 60 to 90, or in the range of 70 to 80.

The non-crosslinkable terminal group-containing siloxane resin may have a relatively lower viscosity than the crosslinkable terminal group-containing siloxane resin. In some embodiments, the non-crosslinkable terminal group-containing siloxane resin may have a viscosity of 30 cps to 130 cps at 25 ^o C. In the above viscosity range, the curing time can be appropriately controlled without lowering the ductility of the gap filler.

Preferably, the viscosity of the non-crosslinkable terminal group-containing siloxane resin may be from 30 cps to 90 cps, more preferably from 40 cps to 90 cps.

The content of the non-crosslinkable terminal group-containing siloxane resin may be 0.02 wt% to 0.2 wt% of the total weight of the gap filler composition. Within the above range, the curing speed of the gap filler composition is maintained within an appropriate range and ductility can be secured.

Preferably, the content of the non-crosslinkable terminal group-containing siloxane resin may be 0.05 wt% to 0.15 wt%, more preferably 0.05 wt% to 0.1 wt%.

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

According to exemplary embodiments, the catalyst may comprise an organic-inorganic hybrid catalyst containing platinum and silicon.

The above catalyst may contain Pt atoms and Si ₂ O groups (-Si-O-Si-) within the molecule. For example, silicon (Si) atoms of the Si ₂ O group may be bonded to vinyl groups, and Pt atoms may be coordinated or captured by the vinyl groups.

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

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. According to exemplary embodiments, the filler may include ceramic particles such as alumina (Al ₂ O ₃ ), aluminum nitride (AlN), boron nitride (BN), silicon nitride, SiC, ZnO, aluminum hydroxide (Al(OH) ₃ ), boehmite, BeO, and the like.

In embodiments of the present invention, the filler may include alumina particles, boron nitride (BN) particles, and aluminum hydroxide particles together. In some embodiments, the filler may consist essentially of alumina particles, boron nitride (BN) particles, and aluminum hydroxide particles.

The above alumina particles can be used to improve the thermal conductivity properties of the gap filler. In addition, the boron nitride particles and the aluminum hydroxide particles can be included together to maintain the thermal conductivity of the gap filler while suppressing an excessive increase in the specific gravity of the composition due to the alumina particles.

For example, the specific gravity of the composition and gap filler can be reduced more effectively by including aluminum hydroxide particles.

According to exemplary embodiments, the content of the alumina particles may be 20 wt% to 40 wt%, the content of the aluminum hydroxide particles may be 40 wt% to 70 wt%, and the content of the boron nitride particles may be 2 wt% to 30 wt% of the total weight of the filler.

In some embodiments, the aluminum hydroxide particles may be included in the largest amount among the fillers.

In preferred embodiments, the content of the alumina particles may be 23 wt% to 40 wt%, the content of the aluminum hydroxide particles may be 41 wt% to 60 wt%, and the content of the boron nitride particles may be 2 wt% to 25 wt% of the total weight of the filler.

Within the content range described above, the specific gravity of the composition can be effectively reduced without excessively reducing the thermal conductivity of the gap filler.

In exemplary embodiments, the specific gravity of the gap filler composition may be less than 3, preferably less than 2.5. For example, the specific gravity of the gap filler composition may be from 1.5 to 2.5, more preferably from 1.5 to 2.3.

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

A gap filler having improved mechanical stability and desired heat dissipation characteristics can be obtained without increasing the weight of the battery pack within the above specific gravity range.

According to exemplary embodiments, the filler may include alumina particles surface-treated with a silane agent. The silane agent may be chemically bonded or attached to the surface of the alumina particles to interact with the siloxane-based resin described above to stabilize the filler. Accordingly, the filler may be uniformly dispersed in the gap filler composition, thereby realizing uniform thermal conductivity characteristics within the battery pack.

According to exemplary embodiments, the number of carbon atoms in the alkyl group included in the silane agent may be 8 or more. In this case, interaction with the siloxane-based resin can be effectively promoted.

In some embodiments, the number of carbon atoms in the alkyl group included in the silane agent may be 8 to 16, preferably 8 to 14, more preferably 10 to 14. In this case, the decrease in dispersibility due to an excessive increase in the number of carbon atoms can be prevented.

In some embodiments, the filler may comprise boron nitride particles surface-treated with the silane agent described above.

In some embodiments, the aluminum hydroxide particles included in the filler may be particles that have not been treated with a silane agent. For example, the aluminum hydroxide particles included in an excessive amount in the filler may be included in the form of bare particles, thereby sufficiently lowering the specific gravity of the composition while suppressing a decrease in the thermal conductivity of the gap filler.

According to exemplary embodiments, the alumina particles may include particles (first alumina particles) having an average particle diameter (D50) of 50 μm or more, or 60 μm to 80 μm.

For example, among the total weight of the alumina particles, the content of the first alumina particles may be 50 wt% or more, preferably 60 wt% or more.

In some embodiments, the filler may include a plurality of types of alumina particles having different average particle diameters. Accordingly, the packing properties and distribution properties of the alumina particles within the composition may be improved, and the thermal conductivity properties may be enhanced.

For example, the alumina particles may include first alumina particles, second alumina particles and third alumina particles having sequentially decreasing average particle diameters.

In exemplary embodiments, the average particle diameter (D50) of the third alumina particles may be less than 15 μm. The average particle diameter (D50) of the second alumina particles may be from 15 μm to 30 μm. The average particle diameter (D50) of the first alumina particles may be 50 μm or more.

In a preferred embodiment, the average particle diameter (D50) of the third alumina particles may be 5 μm to 13 μm. The average particle diameter (D50) of the second alumina particles may be 15 μm to 25 μm. The average particle diameter (D50) of the first alumina particles may be 60 μm to 80 μm.

In some embodiments, the first alumina particles among the alumina particles may be included in the largest amount. Accordingly, the heat conduction efficiency through the filler may be sufficiently increased.

For example, among the total weight of the alumina particles, the content of the first alumina particles may be 50 wt% to 70 wt%, the content of the second alumina particles may be 10 wt% to 30 wt%, and the content of the third alumina particles may be 10 wt% to 30 wt%.

Preferably, among the total weight of the alumina particles, the content of the first alumina particles provided as large-diameter particles may be 55 wt% to 65 wt%, the content of the second alumina particles may be 15 wt% to 25 wt%, and the content of the third alumina particles may be 15 wt% to 25 wt%.

As described above, the second alumina particles and the third alumina particles provided as medium-diameter particles and small-diameter particles are distributed together in similar or equal amounts, thereby preventing an increase in brittleness of the gap filler due to the filler and maintaining heat conduction characteristics.

According to exemplary embodiments, the aluminum hydroxide particles may include particles having an average particle diameter (D50) of 45 μm to 90 μm (first aluminum hydroxide particles).

For example, among the total weight of the aluminum hydroxide particles, the content of the first aluminum hydroxide particles may be 50 wt% or more, preferably 60 wt% or more.

In some embodiments, the filler may include a plurality of types of aluminum hydroxide particles having different average particle diameters. Accordingly, the packing properties and distribution properties of the aluminum hydroxide particles within the composition may be improved, and the thermal conductivity properties may be enhanced.

For example, the aluminum hydroxide particles may include first aluminum hydroxide particles, second aluminum hydroxide particles, and third aluminum hydroxide particles, the average particle diameters of which sequentially decrease.

In exemplary embodiments, the average particle diameter (D50) of the third aluminum hydroxide particles may be less than 15 μm. The average particle diameter (D50) of the second aluminum hydroxide particles may be from 20 μm to 35 μm. The average particle diameter (D50) of the first aluminum hydroxide particles may be from 45 μm to 90 μm or more.

In a preferred embodiment, the average particle diameter (D50) of the third aluminum hydroxide particles may be 5 μm to 10 μm. The average particle diameter (D50) of the second aluminum hydroxide particles may be 22 μm to 30 μm. The average particle diameter (D50) of the first aluminum hydroxide particles may be 45 μm to 70 μm.

The term "average particle size (D50)" as used in this application refers to the median particle size corresponding to 50% in a cumulative distribution (e.g., a count-based distribution) in which the particles are distributed in size order.

In some embodiments, the first aluminum hydroxide particles among the aluminum hydroxide particles may be included in the largest amount. Accordingly, the heat conduction efficiency through the filler may be sufficiently increased.

For example, among the total weight of the aluminum hydroxide particles, the content of the first aluminum hydroxide particles may be 50 wt% to 70 wt%, the content of the second aluminum hydroxide particles may be 10 wt% to 30 wt%, and the content of the third aluminum hydroxide particles may be 10 wt% to 30 wt%.

Preferably, among the total weight of the aluminum hydroxide particles, the content of the first aluminum hydroxide particles provided as large-diameter particles may be 55 wt% to 65 wt%, the content of the second aluminum hydroxide particles may be 15 wt% to 25 wt%, and the content of the third aluminum hydroxide particles may be 15 wt% to 25 wt%.

As described above, the second aluminum hydroxide particles and the third aluminum hydroxide particles provided as medium-diameter particles and small-diameter particles are distributed together in similar or equal amounts, thereby preventing an increase in brittleness of the gap filler due to the filler and maintaining the heat conduction characteristics.

In some embodiments, the average particle diameter (D50) of the boron nitride particles may be 20 μm to 40 μm, preferably 25 μm to 35 μm. In the above range, the overall dispersibility of the filler particles can be improved while buffering the decrease in thermal conductivity due to the addition of aluminum hydroxide particles.

In some embodiments, the amount of the filler including the alumina particles, the aluminum hydroxide particles, and the boron nitride particles may be 82 wt% or more and less than 89 wt% of the total weight of the composition (e.g., solid content). When the content of the filler is less than 82 wt%, sufficient thermal conductivity of the gap filler may not be secured. When the content of the filler is 89 wt% or more, the dispersibility of the filler particles may be reduced, so that a gap filler composition in a paste form may not be substantially formed.

Preferably, the amount of the filler may be 82 wt% to 88 wt% of the total weight of the composition, more preferably 82 wt% to 87 wt%.

In some embodiments, the gap filler composition may further include an additive for improving 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 additive may include a flame retardant, a surfactant, a silane coupling agent, a colorant (e.g., a pigment), an antioxidant, a plasticizer, and the like. The additives may be included in the composition as a remainder or extra amount excluding the siloxane-based resin, the catalyst, and the filler described above.

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.

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.

Examples of the above silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, 3-mercapto propyl trimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, 3-isocyanatepropyltriethoxysilane, γ-acetoacetatepropyltrimethoxysilane, and the like.

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

Examples of the plasticizer 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.

The above gap filler composition can be prepared as a two-component composition. For example, the gap filler composition can be prepared by separately preparing the subject composition and the crosslinking composition, and then mixing the subject composition and the crosslinking composition.

According to embodiments of the present invention, the crosslinkable terminal group-containing siloxane resin described above may be commonly included in the subject composition and the crosslinked composition.

As described above, the crosslinkable terminal group-containing siloxane resin may include a low viscosity siloxane resin, a medium viscosity siloxane resin, and a high viscosity siloxane resin. The subject composition may include the low viscosity siloxane resin, the medium viscosity siloxane resin, and the high viscosity siloxane resin. The crosslinking composition may also include the low viscosity siloxane resin, the medium viscosity siloxane resin, and the high viscosity siloxane resin.

The above-described content ranges of the low viscosity siloxane resin, the medium viscosity siloxane resin and the high viscosity siloxane resin can be commonly included in the above-described subject composition and the above-described crosslinked composition.

The amount of the crosslinkable terminal group-containing siloxane resin included in the above-mentioned subject composition and the amount of the crosslinkable terminal group-containing siloxane resin included in the above-mentioned crosslinking composition may be substantially the same or similar.

In some embodiments, the ratio of the amount of the crosslinkable terminal group-containing siloxane resin included in the subject composition to the amount of the crosslinkable terminal group-containing siloxane resin included in the crosslinking composition may be 0.4 to 0.6, preferably 0.45 to 0.55. Within this ratio range, uniform hardness and elasticity can be achieved throughout the composition or gap filler.

The above-mentioned subject composition may further comprise the above-mentioned catalyst and the above-mentioned filler. The above-mentioned crosslinking composition may further comprise the above-mentioned filler.

For example, the crosslinking composition can be mixed in a state where the catalyst is distributed in the subject composition. Accordingly, since the crosslinking composition is introduced in a state where crosslinking points are preliminarily formed in the subject composition, the curing efficiency and curing speed can be improved.

Additionally, as described above, the subject composition and the crosslinking composition may include a siloxane-based resin having substantially the same composition. Accordingly, the process time for producing a gap filler composition having uniform properties is reduced, and the compatibility between the siloxane-based resins is improved, thereby securing faster curing properties.

The filler may be divided and included in the subject composition and the crosslinking composition. In one embodiment, the ratio of the amount of the filler included in the subject composition to the amount of the filler included in the crosslinking composition may be 0.4 to 0.6, preferably 0.45 to 0.55. In the above ratio range, the heat conduction efficiency can be improved through uniform distribution of the filler.

In some embodiments, the crosslinking composition may include the non-crosslinkable terminal group-containing siloxane resin. The non-crosslinkable terminal group-containing siloxane resin may be first added to the crosslinking composition and used as an auxiliary resin to promote mixing with the subject composition.

Accordingly, the mixing time for forming a gap filler composition when mixing the subject composition and the crosslinking composition can be reduced, and the gap filler composition can be directly applied as a gap filler in a battery pack to achieve the desired hardness in a short period of time.

<Battery Pack>

FIG. 1 is a schematic perspective view illustrating a battery pack according to exemplary embodiments.

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).

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 cathode and a negative electrode alternately and repeatedly stacked. The cathode and the negative electrode may be alternately and repeatedly stacked with a separator interposed therebetween. The cathode includes lithium metal oxide as a cathode active material, and the battery cell (112) may be provided as a lithium secondary battery.

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 through a bus bar to define a battery module (110).

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).

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 heat conduction characteristics.

According to exemplary embodiments, the gap filler composition has a low specific gravity and can maintain a target hardness range for a predetermined time range. Accordingly, stable hardness characteristics can be maintained without impairing the overall electric vehicle process efficiency or increasing the weight of the battery pack.

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.

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 W/mK or more. For example, the thermal conductivity of the gap filler (120) may be 10 W/mK or less. In one embodiment, the thermal conductivity of the gap filler (120) may be 2.4 W/mK to 5 W/mK, or 2.4 W/mK to 3.5 W/mK.

Within the above range, sufficient heat dissipation properties can be secured without excessively increasing the specific gravity of the gap filler or gap filler composition.

For example, the thermal conductivity can be measured according to ASTM D5470 standard.

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, preferably 5.4 mm to 5.7 mm. In the above range, sufficient support stability for the battery module (110) is provided, and sufficient thermal conductivity characteristics can be implemented. In addition, the occurrence of a gap between the battery module (110) and the gap filler (120) due to excessive curing can be prevented.

Hereinafter, in order to help understanding of the present invention, experimental examples including specific examples and comparative examples are presented; however, these are only illustrative of the present invention and do not limit the scope of the appended claims. It will be apparent 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.

Examples and Comparative Examples

The subject composition and the crosslinking composition having the components and contents (parts by weight) described in Tables 1 to 3 below were respectively prepared. The alumina particles and boron nitride particles included in the filler were surface-treated with a silane agent of Chemical Formula 4 below, and the amount of the silane agent was included together with the amounts of the alumina particles and the boron nitride particles. Specifically, the alumina particles and the boron nitride particles were mixed with the silane agent in ethanol and reacted for 1 hour while stirring at 300 rpm.

[Chemical Formula 4]

The above fillers were included in the subject composition and the crosslinking composition in the same amounts as described in Tables 1 to 3, respectively.

Specifically, the components of the subject composition and the crosslinking composition, respectively, in Tables 1 and 2 were placed into a paste mixer, mixed and stirred at 600 rpm/500 rpm for 3 minutes, and then defoamed at 1000 rpm/100 rpm for 10 minutes in a vacuum.

The specific ingredients listed in Tables 1 to 3 are as follows.

(1) Siloxane resin containing crosslinkable terminal groups

A-1) Polydimethylsiloxane resin with a viscosity of 270 cps and vinyl group treatment at both ends (DW27, manufactured by Damiepolychem)

A-2) Polydimethylsiloxane resin with a viscosity of 20,000 cps and vinyl group treatment at both ends (DW2000, manufactured by Damiepolychem)

A-3) Polydimethylsiloxane resin with a viscosity of 1,000 cps and vinyl group treatment at both ends (DW100, manufactured by Damie Polychem)

(2) Catalyst (B-1): Pt/Si2O combined catalyst (DW134, Damiepolychem)

(3) Pigment (C-1): Yellow (SPP-1039, Kyungshin Sangsa)

(4) Siloxane resin containing non-crosslinkable terminal groups

D-1) Polydimethylsiloxane resin with hydrogen treatment at both ends (viscosity 65 cps) (Product name: DW520, Dami Polychem)

D-2): Polydimethylsiloxane resin with methyl groups at both ends (viscosity 40 cps) (Product name: XL-02, Biogen)

(5) Filler

Alumina particles

E-1) Average particle size (D50) approx. 70㎛ (DAM-70, Denka)

E-2) Average particle size (D50) approximately 20㎛ (DAM-20, Denka)

E-3) Average particle size (D50) approx. 7㎛ (DAM-7, Denka)

Aluminum hydroxide particles

F-1) Average particle size (D50) approximately 50㎛ (DH-50P, Dongyang Chemical)

F-2) Average particle size (D50) approximately 25㎛ (SH-25B, Dongyang Chemical)

F-3) Average particle size (D50) approx. 8㎛ (SH-8K, Dongyang Chemical)

Boron nitride particles

G-1) Particles with an average particle size of approximately 30㎛

Experimental example

(1) Thermal conductivity measurement

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.

The thermal conductivity of the above resin layer was measured using a hot disk measuring device according to the standard of ISO22007-2. Specifically, a numerical layer of 20 mm in width/length and 6.0 mm in thickness was formed, and the average value was calculated after measuring a total of three times.

(2) Specific gravity measurement

The subject composition and the 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.

Specifically, the weight of the 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.

The evaluation results are listed in Tables 1 to 3 below.

division Example 1 Example 2 Example 3 Example 4 Example
5 Example
6 subject
Composition Crosslinkability
Terminal
Contains siloxane
profit A-1 0.399 0.399 0.399 0.399 0.453 0.345 A-2 4.649 4.649 4.649 4.649 5.273 4.025 A-3 34.871 34.871 34.871 34.871 39.553 30.189 catalyst B-1 0.2 0.2 0.2 0.2 0.2 0.2 Pigment C-1 0.081 0.081 0.081 0.081 0.081 0.081 Bridge
Composition Crosslinkability
Terminal group containing siloxane resin A-1 0.398 0.398 0.398 0.398 0.452 0.344 A-2 4.635 4.635 4.635 4.635 5.259 4.011 A-3 34.765 34.765 34.765 34.765 39.447 30.083 Non-crosslinking
Contains terminal group
Siloxane resin D-1 0.201 0.201 0.201 0.201 0.201 0.201 D-2 0.201 0.201 0.201 0.201 0.201 0.201 filling E-1 53.060 53.064 48.240 32.160 49.848 53.064 E-2 17.690 17.688 16.080 10.720 16.616 17.688 E-3 17.690 17.688 16.080 10.720 16.616 17.688 F-1 75.580 80.400 56.280 80.400 75.576 78.792 F-2 25.190 26.800 18.760 26.800 25.192 26.264 F-3 25.190 26.800 18.760 26.800 25.192 26.264 G-1 13.400 5.360 53.600 40.200 13.400 13.400 Total filler content 455.600 455.600 455.600 455.600 444.880 466.320 Total composition content 536.000 536.000 536.000 536.000 536.000 536.000 Thermal Conductivity (W/mk) 2.6 2.4 3.4 2.5 2.4 2.8 specific gravity 2 2 2 1.9 2 2.2

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative example
5 Comparative example
6 subject
Composition Crosslinkability
Terminal
Contains siloxane
profit A-1 0.399 0.292 0.506 0.399 0.399 0.399 A-2 4.649 3.401 5.897 4.649 4.649 4.649 A-3 34.871 25.507 44.235 34.871 34.871 34.871 catalyst B-1 0.2 0.2 0.2 0.2 0.2 0.2 Pigment C-1 0.081 0.081 0.081 0.081 0.081 0.081 Bridge
Composition Crosslinkability
Terminal group containing siloxane resin A-1 0.398 0.291 0.505 0.398 0.398 0.398 A-2 4.635 3.387 5.883 4.635 4.635 4.635 A-3 34.765 25.401 44.129 34.765 34.765 34.765 Non-crosslinking
Contains terminal group
Siloxane resin D-1 0.201 0.201 0.201 0.201 0.201 0.201 D-2 0.201 0.201 0.201 0.201 0.201 0.201 filling E-1 27.175 53.064 49.848 136.680 0.000 0.000 E-2 9.058 17.688 16.616 45.560 0.000 0.000 E-3 9.058 17.688 16.616 45.560 0.000 0.000 F-1 98.088 80.400 72.360 0.000 136.680 0.000 F-2 32.696 26.800 24.120 0.000 45.560 0.000 F-3 32.696 26.800 24.120 0.000 45.560 0.000 G-1 19.028 16.080 13.400 0.000 0.000 227.800 Total filler content 455.600 477.040 434.160 455.600 455.600 455.600 Total composition content 536.000 536.000 536.000 536.000 536.000 536.000 Thermal Conductivity (W/mk) 2.1 Uneven 1.9 2.1 1 Uneven specific gravity 2 Uneven 1.9 2.9 1.8 Uneven

division Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative example
11 subject
Composition Crosslinkability
Terminal
Contains siloxane
profit A-1 0.399 0.399 0.399 0.399 0.399 A-2 4.649 4.649 4.649 4.649 4.649 A-3 34.871 34.871 34.871 34.871 34.871 catalyst B-1 0.2 0.2 0.2 0.2 0.2 Pigment C-1 0.081 0.081 0.081 0.081 0.081 Bridge
Composition Crosslinkability
Terminal group containing siloxane resin A-1 0.398 0.398 0.398 0.398 0.398 A-2 4.635 4.635 4.635 4.635 4.635 A-3 34.765 34.765 34.765 34.765 34.765 Non-crosslinking
Contains terminal group
Siloxane resin D-1 0.201 0.201 0.201 0.201 0.201 D-2 0.201 0.201 0.201 0.201 0.201 filling E-1 53.064 104.520 0.000 53.064 53.064 E-2 17.688 34.840 0.000 17.688 17.688 E-3 17.688 34.840 0.000 17.688 17.688 F-1 83.616 0.000 104.520 51.456 82.008 F-2 27.872 0.000 34.840 17.152 27.336 F-3 27.872 0.000 34.840 17.152 27.336 G-1 0.000 53.600 53.600 53.600 2.680 Total filler content 455.600 455.600 455.600 455.600 455.600 Total composition content 536.000 536.000 536.000 536.000 536.000 Thermal Conductivity (W/mk) 2.2 3.3 Uneven 2.6 1.9 specific gravity 2.1 2.8 Uneven 2.6 2.3

Referring to Tables 1 to 3, in examples in which alumina particles, aluminum hydroxide particles, and boron nitride particles were used together in a predetermined content range, the thermal conductivity of the gap filler was improved while the specific gravity of the composition was reduced.

In Comparative Example 1, where the amount of alumina particles was reduced, thermal conductivity was reduced. In Comparative Example 2, where the amount of filler was excessively increased, Comparative Example 6, where only boron nitride particles were used, and Comparative Example 9, where the alumina particles were omitted, the filler particles were not substantially uniformly mixed, so a stable composition was not implemented (indicated as “non-uniform”).

In Comparative Example 3, where the amount of filler was excessively reduced, and Comparative Example 5, where only aluminum hydroxide particles were used, the thermal conductivity was excessively reduced.

In Comparative Example 4, where only alumina particles were used as filler, the thermal conductivity decreased compared to the examples, and the specific gravity of the composition increased excessively.

In Comparative Example 7, where boron nitride particles were omitted, the thermal conductivity was also reduced compared to the examples. In Comparative Example 8, where aluminum hydroxide particles were omitted, the specific gravity of the composition was excessively increased.

In Comparative Examples 10 and 11, where the amounts of alumina particles, aluminum hydroxide particles, and boronite particles were outside the range of the examples of the present invention, the specific gravity increased excessively or the thermal conductivity decreased excessively, respectively.

100: Battery pack 110: Battery module
112: Battery cell 120: Gap filler
130: Support plate

Claims (15)

Siloxane resin;
Filler comprising alumina particles, aluminum hydroxide particles and boron nitride particles; and
Contains a catalyst,
The content of the filler in the total weight of the composition is 82 wt% or more and less than 89 wt%,
Among the total weight of the filler, the content of the alumina particles is 20 wt% to 40 wt%, the content of the aluminum hydroxide particles is 40 wt% to 70 wt%, and the content of the boron nitride particles is 2 wt% to 30 wt%.
The alumina particles include first alumina particles having an average particle diameter (D50) of 50 μm or more, second alumina particles having an average particle diameter (D50) in the range of 15 μm to 30 μm, and third alumina particles having an average particle diameter (D50) of less than 15 μm.
A gap filler composition, wherein the content of the first alumina particles is 50 wt% to 70 wt% of the total weight of the alumina particles, the content of the second alumina particles is 10 wt% to 30 wt%, and the content of the third alumina particles is 10 wt% to 30 wt%.
delete delete delete A gap filler composition according to claim 1, wherein the aluminum hydroxide particles include first aluminum hydroxide particles having an average particle diameter (D50) in a range of 45 μm to 90 μm.
A gap filler composition according to claim 5, wherein the aluminum hydroxide particles include second aluminum hydroxide particles having an average particle diameter (D50) in a range of 20 μm to 35 μm, and third aluminum hydroxide particles having an average particle diameter (D50) of less than 15 μm.
A gap filler composition according to claim 6, wherein the content of the first aluminum hydroxide particles among the total weight of the aluminum hydroxide particles is 50 wt% or more and 70 wt% or less.
A gap filler composition according to claim 1, wherein the average particle diameter (D50) of the boron nitride particles is in a range of 20 μm to 40 μm.
In claim 1, the gap filler composition comprises the alumina particles and the boron nitride particles, each of which is surface-treated with a silane agent.
A gap filler composition according to claim 9, wherein the aluminum hydroxide particles are particles not treated with a silane agent.
A ^gap filler composition according to claim 1, wherein the siloxane-based resin comprises a low viscosity siloxane-based resin having a viscosity in the range of 200 cps to 400 cps at 25 ^o C, a medium viscosity siloxane-based resin having a viscosity in the range of 800 cps to 1,200 cps at 25 ^o C, and a high viscosity siloxane-based resin having a viscosity in the range of 18,000 cps to 22,000 cps at 25 o C.
A gap filler composition according to claim 11, wherein the low viscosity siloxane resin, the medium viscosity siloxane resin and the high viscosity siloxane resin are each a crosslinkable terminal group-containing siloxane resin.
A gap filler composition according to claim 12, wherein the siloxane-based resin further comprises a siloxane resin containing a non-crosslinkable terminal group.
A gap filler composition according to claim 13, wherein the non-crosslinkable terminal group-containing siloxane resin comprises a first non-crosslinkable terminal group-containing siloxane resin in which both terminals are capped with hydrogen (H) and a second non-crosslinkable terminal group-containing siloxane resin in which both terminals are capped with methyl groups (-CH ₃ ).
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.