Resin composition and battery module comprising same
阅读说明：本技术 树脂组合物和包含其的电池模块 (Resin composition and battery module comprising same ) 是由 赵允京 梁世雨 姜杨求 朴恩淑 金贤硕 朴亨淑 朴相敏 梁荣祚 于 2019-02-19 设计创作，主要内容包括：本申请涉及树脂组合物、包含所述树脂组合物的固化产物的电池模块、其制造方法以及电池组。根据本申请的一个实例,可以改善所述树脂组合物的注射可加工性,可以防止注射设备的过载,并且可以提供具有优异的绝缘特性的电池模块。(The present application relates to a resin composition, a battery module including a cured product of the resin composition, a method of manufacturing the same, and a battery pack. According to an example of the present application, injection processability of the resin composition may be improved, overload of an injection apparatus may be prevented, and a battery module having excellent insulation characteristics may be provided.)
1. A resin composition comprising a main resin and a curing agent, and satisfying the following equations 1 and 2:
[ equation 1]
Initial load value (Li) is more than or equal to 10 and less than or equal to 40
[ equation 2]
The load change rate (Lf/Li) is more than or equal to 1 and less than or equal to 3
Wherein Li is an initial load value (kgf) measured immediately after mixing the main resin and the curing agent, and Lf is an elapsed load value (kgf) measured at 3 minutes after mixing the main resin and the curing agent.
2. The resin composition according to claim 1, wherein Lf is 50kgf or less.
3. The resin composition of claim 1, wherein the viscosity measured at the point of 2.5/sec is from 150,000cP to 500,000cP when the viscosity is measured at room temperature at a shear rate range of 0.01/sec to 10.0/sec within 60 seconds after mixing the main resin and the curing agent.
4. The resin composition according to claim 1, wherein a thixotropic index measured at room temperature within 60 seconds after the main resin and the curing agent are mixed is 1.5 or more.
5. The resin composition of claim 1, wherein the primary resin comprises a silicone resin, a polyol resin, an epoxy resin, or an acrylic resin.
6. The resin composition of claim 5, wherein the silicone resin, the polyol resin, the epoxy resin, or the acrylic resin has a viscosity of less than 10,000cP measured at a point of 2.5/sec, measured according to a shear rate range of 0.01/sec to 10.0/sec at room temperature.
7. The resin composition of claim 1, wherein the primary resin comprises a filler and a polyol resin, and the curing agent comprises a filler and a polyisocyanate.
8. The resin composition according to claim 7, wherein the polyol resin is represented by the following formula 1 or 2:
[ formula 1]
[ formula 2]
Wherein X is a carboxylic acid derived unit, Y is a polyol derived unit, n is a number in the range of 2 to 10, m is a number in the range of 1 to 10, and R1And R2Each independently an alkylene group having 1 to 14 carbon atoms.
9. The resin composition of claim 8, wherein the carboxylic acid derived units X are derived from one or more compounds selected from the group consisting of: a fatty acid compound, an aromatic compound having two or more carboxyl groups, an alicyclic compound having two or more carboxyl groups, and an aliphatic compound having two or more carboxyl groups.
10. The resin composition according to claim 9, wherein the aromatic compound having two or more carboxyl groups is phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, tetrahydrophthalic acid, hexahydrophthalic acid, or tetrachlorophthalic acid.
11. The resin composition according to claim 9, wherein the alicyclic compound having two or more carboxyl groups is tetrahydrophthalic acid or hexahydrophthalic acid.
12. The resin composition according to claim 9, wherein the aliphatic compound having two or more carboxyl groups is oxalic acid, adipic acid, azelaic acid, sebacic acid, succinic acid, malic acid, glutaric acid, malonic acid, pimelic acid, suberic acid, 2-dimethylsuccinic acid, 3-dimethylglutaric acid, 2-dimethylglutaric acid, maleic acid, fumaric acid, or itaconic acid.
13. The resin composition of claim 8, wherein the polyol-derived units Y are derived from one or more compounds selected from the group consisting of: alicyclic compounds having two or more hydroxyl groups and aliphatic compounds having two or more hydroxyl groups.
14. The resin composition according to claim 13, wherein the alicyclic compound having two or more hydroxyl groups is 1, 3-cyclohexanedimethanol or 1, 4-cyclohexanedimethanol.
15. The resin composition according to claim 13, wherein the aliphatic compound having two or more hydroxyl groups is ethylene glycol, propylene glycol, 1, 2-butanediol, 2, 3-butanediol, 1, 3-propanediol, 1, 3-butanediol, 1, 4-butanediol, 1, 6-hexanediol, neopentyl glycol, 1, 2-ethylhexyl glycol, 1, 5-pentanediol, 1, 9-nonanediol, 1, 10-decanediol, glycerol, or trimethylolpropane.
16. The resin composition of claim 7, wherein the polyisocyanate is an alicyclic polyisocyanate, a carbodiimide-modified polyisocyanate of an alicyclic polyisocyanate, or an isocyanurate-modified polyisocyanate of an alicyclic polyisocyanate.
17. The resin composition of claim 7, wherein the filler isComprising fumed silica, clay, calcium carbonate (CaCO)3) Zinc oxide (ZnO), aluminum hydroxide (Al (OH)3) Alumina (Al)2O3) Aluminum nitride, boron nitride, silicon nitride, SiC, BeO or carbon fillers.
18. The resin composition according to claim 7, wherein the filler is contained in an amount of 50 parts by weight to 2,000 parts by weight with respect to 100 parts by weight of the sum of the polyol resin and the polyisocyanate.
19. A battery module, comprising: a module case having a top plate, a bottom plate, and sidewalls, wherein an inner space is formed by the top plate, the bottom plate, and the sidewalls;
a plurality of battery cells present in the interior space of the module case; and
a resin layer which is a cured layer of the resin composition according to claim 1 and is in contact with at least one of the bottom plate or the side surface and the plurality of battery cells.
20. A method for manufacturing a battery module, comprising the steps of:
injecting the resin composition of claim 1 into a module housing having a top plate, a bottom plate, and sidewalls, wherein an interior space is formed by the top plate, the bottom plate, and the sidewalls;
receiving a plurality of battery cells in the module housing; and
curing the resin composition.
21. A battery pack comprising one or more battery modules according to claim 19.
22. An automobile comprising the battery pack according to claim 21.
Technical Field
The present application claims the benefit of priority based on korean patent application No. 10-2018-0046255, filed on 20/4/2018, the disclosure of which is incorporated herein by reference in its entirety.
The present application relates to a resin composition. In particular, the present application relates to a resin composition, a battery module including a cured product of the resin composition, a method for manufacturing the battery module, a battery pack, and an automobile.
Background
The secondary battery includes a nickel-cadmium battery, a nickel-hydrogen battery, a nickel-zinc battery, a lithium secondary battery, or the like, of which a typical example is a lithium secondary battery.
Lithium secondary batteries mainly use lithium oxide and carbon materials as a positive electrode active material and a negative electrode active material, respectively. The lithium secondary battery includes: an electrode assembly in which positive and negative electrode plates coated with positive and negative electrode active materials, respectively, are provided with a separator interposed therebetween; and an exterior material in which the electrode assembly and the electrolyte are sealed and accommodated, the lithium secondary battery may be classified into a can type secondary battery and a pouch type secondary battery according to the kind of the exterior material. Such a single secondary battery may be referred to as a battery cell.
In the case of middle-and large-sized devices, such as automobiles or power storage systems, for capacity and power, a battery module in which a plurality of battery cells are electrically connected to each other may be used or a battery pack in which a plurality of such battery modules are connected may be used.
One of the methods of constructing the above battery module or battery pack is to use an adhesive material capable of fixing a plurality of battery cells inside the battery module. At this time, the adhesive material may be injected into the battery module through injection holes formed on the surface of the battery module.
Disclosure of Invention
Technical problem
An object of the present application is to improve injection workability and prevent overload of an injection device in a resin composition that can be used to fix a battery cell in a battery module.
It is another object of the present application to provide a composition that may provide excellent insulation characteristics, adhesive force, heat generation, etc. after being injected into a battery module and cured.
It is another object of the present application to provide a battery module comprising a cured product of the resin composition, a method of manufacturing the same, and a battery pack.
Technical scheme
In one example related to the present application, the present application relates to a resin composition for a battery module or a battery pack. In particular, the composition of the present application may be a composition for fixing one or more battery cells in a battery module by being injected into a housing of the battery module and being in contact with the battery cells present in the battery module, as described below.
In this regard, the resin composition, for example, the adhesive composition, may be a resin composition that includes a main resin and a curing agent and satisfies the following
[ equation 1]
Initial load value (Li) is more than or equal to 10 and less than or equal to 40
[ equation 2]
The load change rate (Lf/Li) is more than or equal to 1 and less than or equal to 3
In the
In the present application, the term "room temperature" is a state without particular heating, and may mean any temperature in the range of about 10 ℃ to 30 ℃, for example, a temperature of about 15 ℃ or more, 18 ℃ or more, 20 ℃ or more, or about 23 ℃ or more and about 27 ℃ or less. In the physical properties mentioned herein, when the measurement temperature affects the physical properties, the physical properties may be physical properties measured at room temperature unless otherwise specified.
In the present application, with respect to the initial load value (Li) measured immediately after mixing the main resin and the curing agent, the main resin and the curing agent were respectively injected into two cartridges as described below, injected into a mixer as described below by pressurizing the cartridges at a uniform speed of 1 mm/sec with a pressurizing device as described below, and mixed in the mixer, and then the force required for the pressurizing device was measured from the first discharge time, thereby setting the maximum value at the point at which the force had the maximum value as the initial load value (Li). The maximum is the maximum determined first in the process, which is the maximum at the point where the required force first increases and then decreases, or at the point where the required force first converges. Then, when the times at which the maximum values are determined by the two pressurizing means are different, the initial load value (Li) is the maximum value that is determined first.
In the present application, as for the elapsed load value (Lf) measured at 3 minutes after the main resin and the curing agent were mixed, the main resin and the curing agent were injected into the mixer by the pressurizing means described below, respectively, the pressurization was stopped when the resin composition injected into the mixer became about 95% of the capacity (volume) of the mixer, the mixer was pressurized again at a uniform speed of 1 mm/sec after the lapse of 3 minutes from the stop time, and the required force was measured from the time when the resin composition was first discharged through the discharge portion of the mixer, thereby setting the maximum value at the point at which the force had the maximum value as the elapsed load value (Lf). The maximum is the maximum determined first in the process, which is the maximum at the point where the required force first increases and then decreases, or at the point where the required force first converges. Then, when the times at which the maximum values are determined by the two pressurizing devices are different, the elapsed load value (Lf) is the maximum value that is determined first.
After charging the main resin into either one of the two cartridges described below and the curing agent into the other cartridge, they were mixed in a mixer described below via the discharge portion of the cartridge described below by applying a constant force with a pressurizing device described below, and then the load value was measured at the time of discharge to the discharge portion of the mixer described below. The initial load value (Li) of the resin composition measured immediately after mixing the main resin and the curing agent may be about 10kgf or more to about 40kgf or less. In one example, the initial load value (Li) may be about 10kgf or more, 12kgf or more, or about 14kgf or more, and may be about 40kgf or less, 38kgf or less, or about 36kgf or less.
Further, the value of the load with time (Lf) measured at 3 minutes after mixing the main resin and the curing agent may be about 50kgf or less, and the lower limit thereof may be, for example, about 20kgf or more. In one example, the elapsed load value measured after 3 minutes of cure may be about 50kgf or less, or about 48kgf, and may be about 20kgf or more, 22kgf or more, or about 24kgf or more.
Such a load value is particularly advantageous in forming a battery module having a specific structure as described below, and an excessively low load value may cause flooding after injection or may deteriorate the storage stability of the resin composition. In addition, an excessively high load value may apply strain to an injection apparatus of the resin composition, thereby shortening the life of the apparatus, or may deteriorate the productivity of the battery module.
In one example, the rate of change of load of the resin composition may be in a range of about 1 or more to about 3 or less. In the present application, the term load change rate is a ratio of an initial load value (Li) measured immediately after mixing the main resin and the curing agent with respect to an elapsed load value (Lf) measured at 3 minutes after mixing the main resin and the curing agent. That is, it may be defined as Lf/Li.
A load change rate of more than 3 means that the increase in the load value is large, which means that the curing rate of the resin composition is fast and thus may cause overload of the injection apparatus. On the other hand, a load change rate of less than 1 means that the increase in the load value is not large, which means that the curing rate of the resin composition is slow, and the productivity of the battery module may deteriorate.
Therefore, when the initial load value (Li) of the resin composition satisfies the
In the present application, Li and Lf may be referred to as temporary curing load values. In the present application, the temporary curing may mean that the resin composition does not reach a true cured state, wherein the true cured state means a state in which the material injected into the module may be considered to have cured enough to serve as an adhesive to be imparted with a function such as actual heat dissipation in order to manufacture the battery module. Taking the urethane resin as an example, the real curing state can be determined by the following steps of 2250cm-1The fact that the conversion of the NCO peak in the vicinity was 80% or more was confirmed by FT-IR analysis based on curing at room temperature and 30% to 70% relative humidity for 24 hours.
In the present application, the mixing machine may comprise two cartridges and one mixer associated with the cartridges. Fig. 1 is a sectional view showing an
The
The
[ equation 3]
V＜t2/td*Q
In the
In one example, the viscosity value of the resin composition can be about 500,000cP or less. The lower limit may be, for example, about 150,000cP or greater. In one example, the viscosity value of the resin composition may be about 450,000cP or less, 400,000cP or less, or about 350,000cP or less, and may be about 160,000cP or more, 180,000cP or more, or about 200,000cP or more. When the relevant range is satisfied, it is advantageous to satisfy the
On the other hand, in the present application, unless otherwise mentioned, when the viscosity is measured at a shear rate range of 0.01/sec to 10.0/sec using a rheological property measuring Apparatus (ARES) at room temperature within 60 seconds after mixing the main resin and the curing agent, it is a viscosity value measured at a point of 2.5/sec.
In one example, the thixotropic index of the resin composition may be about 1.5 or greater, and the upper limit may be, for example, about 5.0 or less. In one example, the thixotropic index may be about 1.5 or greater, 1.6 or greater, or about 1.7 or greater, and may be about 5.0 or less, 4.5 or less, 4.0 or less, or about 3.5 or less.
The thixotropic index represents the viscosity ratio of the resin composition. In the present application, when the thixotropic index is measured at room temperature using a rheology measuring Apparatus (ARES) at a shear rate ranging from 0.01/sec to 10.0/sec, it represents a viscosity ratio of the resin composition measured at a point at which the shear rate is 0.25/sec and a point at which the shear rate is 2.5/sec.
A thixotropic index of less than 1.5 is not suitable for use in the injection process because the viscosity of the resin composition at the point where the shear rate is 0.25/sec does not differ much from the viscosity of the resin composition at the point of 2.5/sec, and even a resin composition having the same viscosity is not preferable because flow may occur before curing. On the other hand, if the viscosity of the resin composition at the point of 2.5/sec is small, flooding may occur due to insufficient curing of the resin composition in a pressurizing device that pressurizes the resin composition in a mixing machine and injects it into a battery module. Therefore, when the thixotropic index is in the range of about 1.5 or more to about 5.0 or less, proper processability can be ensured.
The type of the resin composition is not particularly limited as long as it has the load value of
In one example, as the resin composition, a room temperature curable composition may be used as the resin composition. The room-temperature-curable composition means a composition having a system capable of exhibiting a predetermined adhesive ability by a curing reaction at room temperature, and may be, for example, a two-component resin composition comprising a main resin and a curing agent. As the main resin, a silicone resin, a polyol resin, an epoxy resin, or an acrylic resin can be used. On the other hand, as the curing agent, a known curing agent suitable for the main resin may be used. In one example, when the main resin is a silicone resin, a siloxane compound may be used as a curing agent; when the main resin is a polyol resin, an isocyanate compound may be used as a curing agent; when the main resin is an epoxy resin, an amine compound may be used as a curing agent; and when the main resin is an acrylic resin, an isocyanate compound may be used as the curing agent.
In one example, the viscosity of the primary resin may be about 10,000cP or less. Specifically, the viscosity of the resin component may be about 8,000cP or less, 6,000cP or less, 4,000cP or less, 2,000cP or less, or about 1,000cP or less. Preferably, the upper limit of viscosity can be about 900cP or less, 800cP or less, 700cP or less, 600cP or less, 500cP or less, or about 400cP or less. Although not particularly limited, the lower viscosity limit of the main resin may be about 50cP or more, or about 100cP or more. If the viscosity is too low, the workability may be good, but since the molecular weight of the raw material is low, the possibility of volatilization may increase, and heat/cold resistance, flame retardancy, and adhesion may deteriorate, wherein such disadvantages may be prevented by satisfying the lower limit range. The viscosity of the resin can be measured at room temperature, for example, using a Brookfield LV type viscometer.
In one example, the resin composition may be a two-part urethane-based composition. When a two-part urethane-based composition is used, the composition may have the following constitution. In the case of a two-component polyurethane, a main material containing a polyol or the like and a curing agent containing an isocyanate or the like can be reacted and cured at room temperature. The curing reaction may be assisted by a catalyst such as dibutyltin dilaurate (DBTDL). Thus, the two-part urethane-based composition may comprise a physical mixture of a main component (polyol) and a curing agent component (isocyanate), and/or may comprise reactants of the main component and the curing agent component (cured product).
The two-part urethane-based composition may include a main resin containing at least a polyol resin and a curing agent containing at least an isocyanate. Thus, the cured product of the resin composition may comprise both polyol-derived units and polyisocyanate-derived units. At this time, the polyol-derived unit may be a unit formed by urethane-reacting a polyol with a polyisocyanate, and the polyisocyanate-derived unit may be a unit formed by urethane-reacting a polyisocyanate with a polyol.
The primary resin and the curing agent may each comprise a filler. For example, the compositions of the present application may contain an excess amount of filler, as described below, in order to ensure the thixotropy required in the process and/or to ensure heat dissipation (thermal conductivity) within the battery module or pack. The details will be described in detail in the following related description.
In one example, an ester polyol resin may be used as the polyol resin contained in the main resin. When the ester polyol resin is used, it may be advantageous to ensure excellent adhesion and adhesion reliability in the battery module after curing the resin composition.
In one example, as the ester polyol resin, for example, a carboxylic acid polyol or a caprolactone polyol may be used.
Carboxylic acid polyols may be formed by reacting components comprising a carboxylic acid and a polyol (e.g., a diol or triol), and caprolactone polyols may be formed by reacting components comprising caprolactone and a polyol (e.g., a diol or triol). In this case, the carboxylic acid may be a dicarboxylic acid.
In one example, the polyol resin may be a polyol resin represented by the following
[ formula 1]
[ formula 2]
In
As used herein, the term "carboxylic acid-derived unit" may mean a moiety other than a carboxyl group in a carboxylic acid compound. Similarly, as used herein, the term "polyol-derived units" can mean moieties in the polyol compound structure other than hydroxyl groups.
That is, when the hydroxyl group of the polyol reacts with the carboxyl group of the carboxylic acid, water (H) is eliminated by the condensation reaction2O) molecules to form ester linkages. Thus, when carboxylic acids form ester bonds by condensation reactions, the carboxylic acids are derivatizedThe unit of (b) may mean a portion of the carboxylic acid structure that does not participate in the condensation reaction. Further, polyol-derived units may mean portions of the polyol structure that do not participate in condensation reactions.
Further, after the polyol forms an ester bond with caprolactone, Y in
On the other hand, when the polyol-derived unit Y in the above formula is a unit derived from a polyol having three or more hydroxyl groups, for example, a triol unit, a branched structure may be realized in the Y portion in the formula structure.
In
In one example, the aromatic compound having two or more carboxyl groups may be phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, or tetrachlorophthalic acid.
In one example, the cycloaliphatic compound having two or more carboxyl groups may be tetrahydrophthalic acid, hexahydrophthalic acid, or tetrachlorophthalic acid.
Further, in one example, the aliphatic compound having two or more carboxyl groups may be oxalic acid, adipic acid, azelaic acid, sebacic acid, succinic acid, malic acid, glutaric acid, malonic acid, pimelic acid, suberic acid, 2-dimethylsuccinic acid, 3-dimethylglutaric acid, 2-dimethylglutaric acid, maleic acid, fumaric acid, or itaconic acid.
From the viewpoint of a low glass transition temperature within the above range, the aliphatic carboxylic acid-derived units may be preferred to the aromatic carboxylic acid-derived units.
On the other hand, in
In one example, the cycloaliphatic compound having two or more hydroxyl groups can be 1, 3-cyclohexanedimethanol or 1, 4-cyclohexanedimethanol.
Further, in one example, the aliphatic compound having two or more hydroxyl groups may be ethylene glycol, propylene glycol, 1, 2-butanediol, 2, 3-butanediol, 1, 3-propanediol, 1, 3-butanediol, 1, 4-butanediol, 1, 6-hexanediol, neopentyl glycol, 1, 2-ethylhexyl glycol, 1, 5-pentanediol, 1, 9-nonanediol, 1, 10-decanediol, glycerol, or trimethylolpropane.
On the other hand, in the
Further, in the
If n and m in
In
As described below, the molecular weight of the polyol may be adjusted in consideration of low viscosity characteristics, durability, adhesion, or the like, which may be in the range of, for example, about 300 to 2,000. In the present specification, unless otherwise specified, "molecular weight" may be a weight average molecular weight (Mw) measured using GPC (gel permeation chromatography). If the above range is exceeded, the reliability of the resin layer after curing may be poor and problems related to volatile components may occur.
In the present application, the kind of polyisocyanate contained in the curing agent is not particularly limited, but in order to ensure desired physical properties, a non-aromatic isocyanate compound containing no aromatic group may be used. When an aromatic polyisocyanate is used, the reaction rate may be too fast and the glass transition temperature of the cured product may be increased, so that it may be difficult to ensure processability and physical properties suitable for use of the composition of the present application.
As the non-aromatic isocyanate compound, for example, aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, norbornane diisocyanate methyl, ethylene diisocyanate, propylene diisocyanate or tetramethylene diisocyanate; alicyclic polyisocyanates such as trans-cyclohexane-1, 4-diisocyanate, isophorone diisocyanate, bis (isocyanatomethyl) cyclohexane diisocyanate or dicyclohexylmethane diisocyanate; or the aforementioned one or more carbodiimide-modified polyisocyanates or isocyanurate-modified polyisocyanates; and so on. Furthermore, mixtures of two or more of the above listed compounds may be used.
The ratio of the polyol-derived resin component to the polyisocyanate-derived resin component in the resin composition is not particularly limited, and it may be appropriately adjusted so that urethane reaction therebetween may be performed.
As described above, in order to ensure heat dissipation (thermal conductivity) or thixotropy required in the process, an excessive amount of filler may be included in the composition, wherein if an excessive amount of filler is used, the viscosity of the composition increases, so that the processability when the composition is injected into the case of the battery module may be deteriorated. Therefore, low viscosity characteristics sufficient not to interfere with processability are required while containing an excessive amount of filler. In addition, when only low viscosity is exhibited, it is also difficult to ensure workability, so that it may be necessary that appropriate thixotropy is required, excellent adhesion is exhibited upon curing, and curing itself is performed at room temperature. Then, the ester polyol is advantageous for securing adhesiveness after curing, but it is highly crystallized, so that there is a high possibility of becoming waxy at room temperature and there is a disadvantage in securing proper injection workability due to an increase in viscosity. Even if it is used by reducing the viscosity through melting, the viscosity is increased by crystallization during injection or application of the composition, which may continue after mixing with the filler, occurs during storage due to naturally occurring crystallinity, and thus, processability may be reduced. In view of this, the ester polyol used in the present application may satisfy the following characteristics.
In the present application, the ester polyol may be an amorphous polyol or a polyol with sufficiently low crystallinity. As used herein, the meaning of the term "amorphous" is well known to those skilled in the art. For example, "amorphous" means that the crystallization temperature (Tc) and melting temperature (Tm) are not observed in DSC (differential scanning calorimetry) analysis. At this time, the DSC analysis may be performed at a rate of 10 ℃/min in the range of-80 ℃ to 60 ℃, for example, such a method may be performed: the temperature was increased from 25 ℃ to 60 ℃ at the above rate, and then the temperature was again decreased to-80 ℃ and again increased to 60 ℃. Herein, "sufficiently low crystallinity" means a case where the melting point (Tm) observed in DSC analysis is lower than 15 ℃, which is about 10 ℃ or lower, 5 ℃ or lower, 0 ℃ or lower, -5 ℃ or lower, -10 ℃ or lower, or about-20 ℃ or lower. At this time, the lower limit of the melting point is not particularly limited, but for example, the melting point may be about-80 ℃ or higher, about-75 ℃ or higher, or about-70 ℃ or higher. When the polyol is crystalline or has high (room temperature) crystallinity, for example, does not satisfy the melting point range, the viscosity difference depending on temperature easily increases, so that the degree of dispersion of the filler and the viscosity of the final mixture may be adversely affected during mixing of the filler and the resin, workability decreases, and thus, it may become difficult to satisfy cold resistance, heat resistance, and water resistance required in the adhesive composition for a battery module.
In one example, the glass transition temperature (Tg) of the resin component included in the urethane-based composition after curing (true curing) may be less than 0 ℃.
When the glass transition temperature range is satisfied, even at a low temperature at which the battery module or the battery pack can be used, the brittle characteristic can be ensured in a relatively short time, thereby ensuring impact resistance and vibration resistance. On the other hand, if the above range is not satisfied, the adhesive property of the cured product may be excessively high or the thermal stability may be lowered. In one example, the lower limit of the glass transition temperature of the urethane-based composition after curing may be about-70 ℃ or higher, -60 ℃ or higher, -50 ℃ or higher, -40 ℃ or higher, or about-30 ℃ or higher, and the upper limit may be about-5 ℃ or lower, -10 ℃ or lower, -15 ℃ or lower, or about-20 ℃ or lower.
Further, in the present application, an additive may be used to ensure the use of the resin composition and the functions required according to the use thereof. For example, the resin composition may contain a predetermined filler in consideration of thermal conductivity, insulation characteristics, heat resistance (TGA analysis), and the like of the resin layer. The form or method in which the filler is contained in the resin composition is not particularly limited. For example, the filler may be used in a state where it is previously contained in the main resin and/or the curing agent to form the urethane-based composition. Alternatively, in the process of mixing the main resin and the curing agent, separately prepared fillers may also be used by a method of mixing them together.
In one example, the filler included in the composition may be at least a thermally conductive filler. In the present application, the term thermally conductive filler may mean a material having a thermal conductivity of about 1W/mK or greater, 5W/mK or greater, 10W/mK or greater, or about 15W/mK or greater. Specifically, the thermally conductive filler may have a thermal conductivity of about 400W/mK or less, about 350W/mK or less, or about 300W/mK or less. The kind of the heat conductive filler that can be used is not particularly limited, but when insulation properties and the like are considered together, it may be a ceramic filler. For example, alumina (Al) can be used2O3) Aluminum nitride, boron nitride, silicon nitride, SiC or BeCeramic particles of O. The shape or ratio of the filler is not particularly limited, and may be appropriately adjusted in consideration of the viscosity of the urethane-based composition, the possibility of sedimentation in the cured resin layer of the composition, desired heat resistance or thermal conductivity, insulating properties, filling effect or dispersibility, and the like. Generally, the larger the size of the filler, the higher the viscosity of the composition containing it and the higher the likelihood of the filler precipitating in the resin layer. Further, the smaller the size, the thermal resistance tends to increase. Therefore, the filler having an appropriate type and size may be selected in consideration of the above points, and two or more fillers may also be used according to need. The use of spherical fillers is advantageous in view of the amount of filling, but fillers in a form such as a needle-like form or a flat form may also be used in view of network formation or conductivity.
In one example, the composition may include thermally conductive fillers having an average particle size in a range of about 0.001 μm to about 80 μm. In another example, the filler can have an average particle size of about 0.01 μm or greater, 0.1 μm or greater, 0.5 μm or greater, 1 μm or greater, 2 μm or greater, 3 μm or greater, 4 μm or greater, 5 μm or greater, or about 6 μm or greater. In another example, the filler can have an average particle size of about 75 μm or less, 70 μm or less, 65 μm or less, 60 μm or less, 55 μm or less, 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, 10 μm or less, or 5 μm or less.
In order to obtain excellent heat dissipation performance, it may be considered to use a high content of the thermally conductive filler. For example, the filler may be used in an amount of about 50 parts by weight to 2,000 parts by weight, relative to 100 parts by weight of the total resin components (i.e., the sum of the ester polyol resin and the polyisocyanate content). In another example, filler content in excess of the total resin component may be used. Specifically, the filler may be used in an amount of 100 parts by weight or more, 150 parts by weight or more, 200 parts by weight or more, 250 parts by weight or more, 300 parts by weight or more, 350 parts by weight or more, 400 parts by weight or more, 500 parts by weight or more, 550 parts by weight or more, 600 parts by weight or more, or about 650 parts by weight or more, relative to 100 parts by weight of the sum of the ester polyol resin and the polyisocyanate content.
As described above, when the thermally conductive filler is used at a high content, the viscosity of the main resin or curing agent containing the filler or a composition containing the same may increase.
As described above, when the viscosity of the resin composition is too high, injection processability is poor, and thus physical properties required for the resin layer may not be sufficiently achieved in the entire resin layer. In view of this, it is preferable to use a low-viscosity component which may be liquid or have sufficient fluidity as the resin component.
In addition to the above, various fillers may be used. For example, it is conceivable to use a carbon (carbon-based) filler such as graphite to ensure the insulating property of the cured resin layer of the resin composition. Alternatively, a material such as fumed silica, clay, calcium carbonate, zinc oxide (ZnO) or aluminum hydroxide (Al (OH)3) The filler of (3). The form or content ratio of the filler is not particularly limited, and may be selected in consideration of the viscosity of the resin composition, the possibility of sedimentation in the resin layer, thixotropy, insulating properties, filling effect, or dispersibility.
The composition may further comprise a viscosity control agent, such as a thixotropic agent, a diluent, a dispersing agent, a surface treatment agent or a coupling agent, as necessary, for adjusting the viscosity, for example, for increasing or decreasing the viscosity or for controlling the viscosity according to a shear force.
The thixotropic agent controls the viscosity of the resin composition according to a shear force, whereby the process of manufacturing the battery module can be efficiently performed. Examples of useful thixotropic agents include fumed silica and the like.
The diluent or dispersant is generally used to reduce the viscosity of the resin composition, and any of various kinds known in the art may be used without limitation so long as it can exhibit the above effects.
The surface treatment agent is used to surface-treat the filler introduced into the resin layer, and any of various kinds known in the art may be used without limitation so long as it can exhibit the above effect.
The coupling agent may be used, for example, to improve dispersibility of the thermally conductive filler such as alumina, and any of various kinds known in the art may be used without limitation so long as it can exhibit the above effect.
In addition, the resin composition may further include a flame retardant or a flame retardant aid. In this case, known flame retardants may be used without any particular limitation, and for example, a flame retardant in a solid phase form or a liquid flame retardant may be applied. Flame retardants include, for example, organic flame retardants such as melamine cyanurate and inorganic flame retardants such as magnesium hydroxide. When the amount of filler filled in the resin layer is large, a liquid type flame retardant material (TEP, i.e., triethyl phosphate; or TCPP, i.e., tris (1, 3-chloro-2-propyl) phosphate, etc.) may also be used. In addition, a silane coupling agent that can be used as a flame retardant synergist may also be added.
In another example for controlling the desired viscosity of the resin composition, the viscosity of the main composition and the curing agent composition may be controlled by controlling the preparation conditions of the main composition including the polyol resin or the curing agent composition including the isocyanate, and thus the viscosity of the resin composition, which is a mixed composition of the main composition and the curing agent composition, may also be controlled. In one example, in the case of preparing a main composition including a main resin, a filler, and a catalyst, when the mixing time or the mixing rpm is increased, the viscosity of the main composition may be increased. In another example, in the case of preparing a curing agent composition comprising an isocyanate and a filler, the viscosity of the curing agent composition may increase when the mixing time or mixing rpm is increased.
The resin composition may include the above-described constitution, and may be a solvent-based composition, a water-based composition, or a solvent-free composition, but a solvent-free type may be suitable in view of the convenience of the manufacturing process.
The resin composition of the present application, after curing, may have physical properties suitable for the uses described below. The expression "after curing" can be used in the same sense as the above true curing with respect to the physical properties.
In one example, the resin composition may have a predetermined adhesive force (S) at room temperature after curing1). Specifically, the adhesive force of the resin layer may be about 150gf/10mm or more, 200gf/10mm or more, 250gf/10mm or more, 300gf/10mm or more, 350gf/10mm or more, or about 400gf/10mm or more. When the adhesive force satisfies the above range, appropriate impact resistance and vibration resistance can be ensured. The upper limit of the adhesive force of the resin layer is not particularly limited, and it may be about 1,000gf/10mm or less, 900gf/10mm or less, 800gf/10mm or less, 700gf/10mm or less, 600gf/10mm or less, or about 500gf/10mm or less. When the adhesive force is too high, there is a risk that the pouch portion to which the cured composition is attached may tear. In particular, in the case where an impact occurs that causes the shape of the battery module to be deformed due to an accident while the vehicle is running, when the battery cells are attached too strongly by the cured resin layer, hazardous materials inside the battery may be exposed or explode while the pouch is torn. Adhesion can be measured relative to an aluminum bag. For example, an aluminum pouch for manufacturing a battery cell is cut to a width of about 10mm, a resin composition is supported on a glass plate, and the cut aluminum pouch is supported thereon such that the resin composition contacts a PET (poly (ethylene terephthalate)) surface of the pouch, and then the adhesive force may be measured while curing the resin composition at 25 ℃ and 50% RH for 24 hours and peeling the aluminum pouch with a tensile tester (texture analyzer) at a peeling angle of 180 ° and a peeling speed of 300 mm/min.
In another example, the adhesive force of the resin composition after curing can be maintained at a considerable level even under high temperature/high humidity. Specifically, in the present application, the adhesive force (S) measured by the same method after the high temperature/high humidity acceleration test performed under predetermined conditions (S)2) Relative to the adhesion measured at room temperature (S)1) Of [ (S) ]ratio2/S1)×100]May be 70% or greater, or 80% or greater. In one embodiment, the high temperature/high humidity accelerated test may be performed on the same test specimen used to measure room temperature adhesion at 40 ℃ to 100 DEG CIs measured after being stored for 10 days under the conditions of temperature of (1) and humidity of 75% RH or more. When the adhesive force and the relationship are satisfied, excellent adhesive durability can be maintained even if the use environment of the battery module is changed.
In one example, the resin composition may have excellent heat resistance after curing. In this regard, the 5% weight loss temperature of the composition herein may be 120 ℃ or higher when thermogravimetric analysis (TGA) is measured on the cured product of only the resin component in a state not containing the filler. Further, when thermogravimetric analysis (TGA) is measured on a cured product of the resin composition in a state containing the filler, the 800 ℃ margin of the composition of the present application may be 70% by weight or more. In another example, the 800 ℃ margin may be about 75 wt% or greater, 80 wt% or greater, 85 wt% or greater, or about 90 wt% or greater. In another example, the 800 ℃ margin may be about 99 wt% or less. At this time, thermogravimetric analysis (TGA) may be at 60cm3Nitrogen gas (N) per minute2) Measured at a ramp rate of 20 ℃/minute under an atmosphere in the range of 25 ℃ to 800 ℃. By controlling the kind of the resin and/or the filler or the content thereof, the heat resistance characteristics associated with the thermogravimetric analysis (TGA) can be ensured.
In one example, the resin composition may provide excellent electrical insulation after curing. In the battery module structure as described below, when the resin layer exhibits electrical insulation, the performance of the battery module may be maintained and stability may be ensured. For example, when the dielectric breakdown voltage of the cured product is measured 24 hours after the components of the resin composition are mixed, the dielectric breakdown voltage may be about 10kV/mm or more, 15kV/mm or more, or about 20kV/mm or more. The higher the value of the dielectric breakdown voltage is, the more excellent the insulation property is exhibited by the resin layer, and therefore the upper limit is not particularly limited, but may be about 50kV/mm or less, 45kV/mm or less, 40kV/mm or less, 35kV/mm or less, or about 30kV/mm or less in consideration of the composition of the resin layer and the like. Dielectric breakdown voltage may be measured according to ASTM D149, as described in the examples below. By adjusting, for example, the filler or the resin component used in the resin composition or the content thereof, the dielectric breakdown voltage in the above range can be ensured.
In another example of the present application, the present application relates to a battery module. The module includes a module housing and a battery cell. The battery cells may be accommodated in the module case. One or more battery cells may be present in the module case, and a plurality of battery cells may be accommodated in the module case. The number of battery cells accommodated in the module case is adjusted according to applications and the like, and is not particularly limited. The battery cells received in the module case may be electrically connected to each other.
The module case may include at least a sidewall and a bottom plate forming an inner space in which the battery cells may be received. In addition, the module case may further include a top plate for sealing the inner space. The side walls, the bottom plate and the top plate are formed integrally with each other, or the side walls, the bottom plate and/or the top plate, which are separate from each other, are assembled so that a module case may be formed. The shape and size of such a module case are not particularly limited, and may be appropriately selected according to the application, or the type and number of battery cells accommodated in the inner space, or the like.
Here, since there are at least two plates constituting the module case, the terms top plate and bottom plate are terms having relative concepts to distinguish them. That is, this does not mean that the top plate is necessarily present at the upper portion and the bottom plate is necessarily present at the lower portion in the actual use state.
Fig. 2 is a view showing an
Fig. 3 is a schematic view of the
Holes may be formed in the bottom, side and/or top panels of the module housing. When the resin layer is formed by an injection process, the hole may be an injection hole for injecting a material for forming the resin layer, i.e., a resin composition. The shape, number, and position of the holes may be adjusted in consideration of injection efficiency of a material for forming the resin layer. In one example, the holes may be formed on at least the bottom plate and/or the top plate.
In one example, the aperture may be formed at about 1/4 to 3/4 points or at about 3/8 to 7/8 points or about midway along the entire length of the side, bottom or top wall. By injecting the resin composition through the injection hole formed at the point, the resin layer can be injected to have a wide contact area. As shown in fig. 4, the 1/4, 3/4, 3/8 or 7/8 point is a ratio of a distance a to a hole forming position measured based on either end face E of the bottom plate or the like, for example, with respect to the entire length L. The end E forming the length L and the distance a may be any end E as long as the length L and the distance a are measured from the same end E. In fig. 4, the
The size and shape of the injection hole are not particularly limited and may be adjusted in consideration of the injection efficiency of the resin layer material. For example, the aperture may have a circular shape, an elliptical shape, a polygonal shape (e.g., triangular or square), or an amorphous shape. The number and interval of the injection holes are not particularly limited and may be adjusted so that the resin layer may have a wide contact area with the substrate or the like.
A viewing hole (e.g., 50b in fig. 4) may be formed at an end of the top and bottom plates, etc., in which the injection hole is formed. For example, when the material of the resin layer is injected through the injection hole, such an observation hole may be formed to observe whether the injected material is well injected to the end of the side wall, the bottom plate, or the top plate. The position, shape, size and number of the observation holes are not particularly limited as long as they are formed so that it can be determined whether the injected material is properly injected.
The module housing may be a thermally conductive housing. The term thermally conductive housing means a housing: wherein the thermal conductivity of the entire housing is 10W/mk or more, or includes at least a portion having thermal conductivity as above. For example, at least one of the side walls, bottom plate, and top plate as described above may have the thermal conductivity described above. In another example, at least one of the side wall, the bottom plate, and the top plate may include a portion having the thermal conductivity. For example, the battery module of the present application may include a first filler-containing cured resin layer in contact with the top plate and the battery cell, and a second filler-containing cured resin layer in contact with the bottom plate and the battery cell, wherein at least the second filler-containing cured resin layer may be a heat conductive resin layer, whereby it can be said that at least the bottom plate may have heat conductivity or may include a heat conductive portion.
Here, the thermal conductivity of the thermally conductive top plate, bottom plate, side wall, or thermally conductive portion may be about 20W/mk or greater, 30W/mk or greater, 40W/mk or greater, 50W/mk or greater, 60W/mk or greater, 70W/mk or greater, 80W/mk or greater, 90W/mk or greater, 100W/mk or greater, 110W/mk or greater, 120W/mk or greater, 130W/mk or greater, 140W/mk or greater, 150W/mk or greater, 160W/mk or greater, 170W/mk or greater, 180W/mk or greater, 190W/mk or greater, or about 195W/mk or greater. From the viewpoint of heat dissipation characteristics of the module and the like, the higher the value of the thermal conductivity, the more advantageous, and the upper limit is not particularly limited. In one example, the thermal conductivity can be, but is not limited to, about 1,000W/mK or less, 900W/mK or less, 800W/mK or less, 700W/mK or less, 600W/mK or less, 500W/mK or less, 400W/mK or less, 300W/mK or less, or about 250W/mK or less. The kind of the material exhibiting thermal conductivity as above is not particularly limited, and for example, includes a metal material such as aluminum, gold, silver, tungsten, copper, nickel, or platinum. The module case may be entirely composed of the above heat conductive material, or at least a part of the module case may be a part composed of the heat conductive material. Thus, the module housing may have a thermal conductivity in the above-mentioned range, or comprise at least a portion having a thermal conductivity as described above.
In the module case, the portion having the thermal conductivity in the above range may be a portion in contact with a resin layer and/or an insulating layer as described below. Further, the portion having the thermal conductivity may be a portion that is in contact with a cooling medium such as cooling water. When it has such a structure, heat generated from the battery cell can be effectively discharged to the outside.
In addition, the type of the battery cells accommodated in the module case is not particularly limited, and various known battery cells may be applied. In one example, the battery cell may be a pouch type. Referring to fig. 5, the pouch type battery cell 100 may generally include an electrode assembly, an electrolyte, and a pouch exterior material.
Fig. 5 is an exploded perspective view schematically showing the configuration of an exemplary bag-type unit, and fig. 6 is an assembled perspective view of the configuration of fig. 5.
The electrode assembly 110 included in the pouch cell 100 may be in the form of: wherein at least one positive electrode plate and at least one negative electrode plate are provided with respective separators interposed therebetween. The electrode assembly 110 may be a winding type in which one positive electrode plate and one negative electrode plate are wound with separators, or a stacking type in which a plurality of positive electrode plates and a plurality of negative electrode plates are alternately laminated with separators interposed therebetween.
The bag exterior material 120 may be configured to be provided with, for example, an outer insulating layer, a metal layer, and an inner adhesive layer. Such an outer material 120 protects the inner elements, such as the electrode assembly 110. The metal layer of the electrode assembly 110 may include a thin metal film such as aluminum in order to protect internal elements such as an electrolyte, to compensate electrochemical characteristics by the electrode assembly 110 and the electrolyte, and to allow for heat dissipation, etc. Such a thin metal film may be interposed between insulating layers formed of an insulating material to ensure electrical insulation from elements such as the electrode assembly 110 and the electrolyte or other elements outside the battery 100. Furthermore, the bag may also comprise, for example, a layer (substrate) of a polymer resin, such as PET.
In one example, the exterior material 120 may include an upper bag 121 and a lower bag 122, wherein a concave inner space I may be formed in at least one of the upper bag 121 and the lower bag 122. The electrode assembly 110 may be housed in the interior space I of the bag. A sealing portion S is provided on the outer circumferential surface of each of the upper and lower bags 121 and 122, and these sealing portions S are joined to each other, so that the inner space in which the electrode assembly 110 is accommodated can be sealed.
Each electrode plate of the electrode assembly 110 is provided with an electrode tab (electrode tab), and one or more electrode tabs may be connected to the electrode lead. The electrode lead may be interposed between the sealing parts S of the upper and lower pouches 121 and 122 and exposed to the outside of the exterior material 120 to serve as an electrode terminal of the pouch assembly 100.
The shape of the pouch type cell as described above is only an example, and the battery cell applied in the present application is not limited to the above-described kind. In the present application, various shapes of known pouch-type cells or other types of cells may be used as the battery cells.
The battery module of the present application may further include a resin layer. Specifically, the battery module of the present application may include a cured resin layer in which the filler-containing composition is cured. The cured resin layer may be formed of the resin composition as described above.
The battery module may have, as resin layers, a first filler-containing cured resin layer in contact with the top sheet and the battery cells and a second filler-containing cured resin layer in contact with the bottom sheet and the battery cells. One or more of the first filler-containing cured resin layer and the second filler-containing cured resin layer may contain a cured product of the resin composition as described above, thereby having predetermined adhesion, cold resistance, heat resistance, and insulation as described above. Further, the first filler-containing cured resin layer and the second filler-containing cured resin layer may have the following characteristics.
In one example, the resin layer may be a thermally conductive resin layer. In this case, the thermal conductivity of the thermal conductive resin layer may be about 1.5W/mK or more, 2W/mK or more, 2.5W/mK or more, 3W/mK or more, 3.5W/mK or more, or about 4W/mK or more. The thermal conductivity can be 50W/mK or less, 45W/mK or less, 40W/mK or less, 35W/mK or less, 30W/mK or less, 25W/mK or less, 20W/mK or less, 15W/mK or less, 10W/mK or less, 5W/mK or less, 4.5W/mK or less, or about 4.0W/mK or less. When the resin layer is a heat conductive resin layer as described above, the bottom plate, the top plate, and/or the side wall, etc. to which the resin layer is attached may be a portion having the above-described thermal conductivity of 10W/mK or more. At this time, the module case portion exhibiting the thermal conductivity may be a portion that is in contact with a cooling medium such as cooling water. The thermal conductivity of the resin layer is a value measured, for example, according to the ASTM D5470 standard or the ISO22007-2 standard. As described above, the thermal conductivity of such a resin layer can be ensured, for example, by appropriately adjusting the filler contained in the resin layer and the content thereof.
In one example, in the battery module, the resin layer or the battery module applied with the resin layer may have a thermal resistance of about 5K/W or less, 4.5K/W or less, 4K/W or less, 3.5K/W or less, 3K/W or less, or about 2.8K/W. When the resin layer or the battery module having the resin layer applied thereto is adjusted to exhibit heat resistance in the above range, excellent cooling efficiency or heat dissipation efficiency can be ensured. The method of measuring thermal resistance is not particularly limited, and for example, thermal resistance can be measured according to ASTM D5470 standard or ISO22007-2 standard.
In one example, the resin layer may be a resin layer formed to maintain durability even in a predetermined thermal shock test. For example, when one cycle consists of holding the battery module at a low temperature of-40 ℃ for 30 minutes and then holding it for 30 minutes after raising the temperature to 80 ℃, it may be a resin layer that is not peeled or cracked from the module case or the battery cell of the battery module after repeating the thermal shock test of the cycle 100 times. For example, when the battery module is applied to a product (e.g., an automobile) requiring a long shelf life (e.g., about 15 years or more in the case of an automobile), the same level of performance as above may be required to ensure durability.
In one example, the resin layer may be a flame retardant resin layer. In the present application, the term flame retardant resin layer may mean a resin layer showing a V-0 rating in a UL 94V test (vertical burning test). This may ensure stability against fire and other accidents that may occur in the battery module.
In one example, the specific gravity of the resin layer may be about 5 or less. In another example, the specific gravity may be about 4.5 or less, 4 or less, 3.5 or less, or about 3 or less. A resin layer exhibiting a specific gravity within this range is advantageous for manufacturing a lightweight battery module. The lower limit is not particularly limited, since the smaller the value of the specific gravity, the more advantageous the weight reduction of the module becomes. For example, the specific gravity may be about 1.5 or greater, or about 2 or greater. The components added to the resin layer may be adjusted so that the resin layer exhibits a specific gravity within the above range. For example, when a filler is added, a method of applying a filler capable of ensuring a desired thermal conductivity even at a low specific gravity (i.e., a filler having a low specific gravity or a surface-treated filler), or the like may be used, if possible.
In one example, it is preferred that the resin layer does not contain volatile substances, if possible. For example, the ratio of the nonvolatile component of the resin layer may be 90 wt% or more, 95 wt% or more, or 98 wt% or more. Here, the nonvolatile components and the ratio thereof may be determined in the following manner. That is, the nonvolatile component may be defined as the remaining portion after the resin layer is maintained at 100 ℃ for about 1 hour. Therefore, the ratio of the nonvolatile components may be measured based on the initial weight of the resin layer and the ratio after holding the resin layer at 100 ℃ for about 1 hour.
In one example, it may be advantageous for the resin layer to have low shrinkage during the curing process or after curing. This may prevent the occurrence of peeling or voids that may occur during the manufacturing or use process of the module. The shrinkage ratio may be appropriately adjusted within a range capable of exhibiting the above-described effects, and may be, for example, less than 5%, less than 3%, or less than about 1%. The lower limit is not particularly limited, since the lower the value of the shrinkage rate, the more favorable the shrinkage rate is.
In one example, the resin layer may have a low Coefficient of Thermal Expansion (CTE) to prevent the occurrence of peeling or voids, etc., that may occur during the manufacturing or using process of the module. The coefficient of thermal expansion may be, for example, less than about 300ppm/K, less than 250ppm/K, less than 200ppm/K, less than 150ppm/K, or less than about 100 ppm/K. The lower the value of the thermal expansion coefficient, the more favorable the coefficient, and therefore the lower limit is not particularly limited.
In one example, the resin layer may have a tensile strength of an appropriate level in order to impart good durability or impact resistance to the battery module. For example, the resin layer may be configured to have a tensile strength of about 1.0MPa or greater.
In one example, the elongation of the resin layer may be appropriately adjusted. Therefore, a module having excellent durability can be provided by ensuring excellent impact resistance and the like. The elongation may be adjusted, for example, in a range of about 10% or more or about 15% or more.
In one example, it may be advantageous for the resin layer to exhibit an appropriate hardness. For example, if the hardness of the resin layer is too high, reliability may be adversely affected due to the brittle characteristics of the resin layer. When this is taken into consideration, by controlling the hardness of the resin layer, impact resistance and vibration resistance can be ensured, and durability of the product can be ensured. The resin layer may have, for example, a shore a hardness of less than about 100, 99 or less, 98 or less, 95 or less, or about 93 or less, or a shore D hardness of less than about 80, about 70 or less, about 65 or less, or about 60 or less. The lower limit of the hardness is not particularly limited. For example, the shore a durometer may be 60 or greater, or the shore OO durometer may be about 5 or greater, or about 10 or greater. The hardness in the above range can be ensured by controlling the content of the filler, etc.
By forming the cured resin layer satisfying the characteristics in the battery module as described above, it is possible to provide a battery module having excellent durability against external impact or vibration.
In the battery module of the present application, at least one of the side wall, the bottom plate, and the top plate, which is in contact with the resin layer, may be the above-described thermally conductive side wall, bottom plate, or top plate. On the other hand, in the present specification, the term contact may also mean, for example, a case where the top plate, the bottom plate, and/or the side wall, or the battery cell is in direct contact with the resin layer, or a case where another element (e.g., an insulating layer, etc.) is present therebetween. Furthermore, the resin layer in contact with the thermally conductive side wall, bottom plate or top plate may be in thermal contact with the target. At this time, the thermal contact may mean a state in which the resin layer is in direct contact with the substrate or the like, or a state in which another element (e.g., an insulating layer or the like described below) is present between the resin layer and the substrate or the like but the other element does not interfere with heat transfer from the battery cell to the resin layer and from the resin layer to the substrate or the like. Here, the phrase "does not interfere with heat transfer" means that even when other elements (e.g., an insulating layer or a guide as described below) are present between the resin layer and the chassis or the like, the overall thermal conductivity of the other elements and the resin layer is about 1.5W/mK or more, 2W/mK or more, 2.5W/mK or more, 3W/mK or more, 3.5W/mK or more, or about 4W/mK or more, or even when other elements are present, the overall thermal conductivity of the resin layer and the chassis or the like in contact therewith is included in the range. The thermal conductivity of the thermal contact can be about 50W/mK or less, 45W/mK or less, 40W/mK or less, 35W/mK or less, 30W/mK or less, 25W/mK or less, 20W/mK or less, 15W/mK or less, 10W/mK or less, 5W/mK or less, 4.5W/mK or less, or about 4.0W/mK or less. When other elements are present, the thermal contact may be achieved by controlling the thermal conductivity and/or thickness of the other elements.
The heat conductive resin layer may be in thermal contact with a base plate or the like, or may be in thermal contact with the battery cell. By adopting such a structure, various fastening parts or module cooling devices and the like, which have been previously required when constructing a general battery module or a battery pack as an assembly of such modules, are greatly reduced, and at the same time, a module that secures heat dissipation characteristics and accommodates more battery cells per unit volume can be realized. Therefore, the present application can provide a battery module having high power while being more compact and lighter.
Fig. 7 is an exemplary sectional view of a battery module. In fig. 7, the module may be in the form of: it comprises a
In the above structure, the base plate or the like in contact with the
The contact area between the resin layer and the base plate or the like may be about 70% or more, about 75% or more, about 80% or more, about 85% or more, about 90% or more, or about 95% or more with respect to the total area of the base plate or the like. The upper limit of the contact area is not particularly limited, and may be, for example, 100% or less, or less than about 100%.
When the top plate or the bottom plate conducts heat and the cured resin layer in contact therewith also conducts heat, the heat conducting portion or the heat conducting bottom plate or the like may be a portion in contact with a cooling medium such as cooling water. That is, as schematically shown in fig. 7, with the above structure, heat H can be easily discharged to the floor panel or the like, and by bringing the floor panel or the like into contact with the cooling medium CW, heat release can be easily performed even in a more simplified structure.
The thickness of the resin layer may be, for example, in the range of about 100 μm to 5mm or in the range of about 200 μm to 5 mm. In the structure of the present application, the thickness of the resin layer may be set to an appropriate thickness in consideration of desired heat dissipation characteristics or durability. The thickness may be the thickness of the thinnest portion, the thickness of the thickest portion, or an average thickness of the resin layer.
As shown in fig. 7, a
In one example, the battery module may further include an insulating layer between the module case and the battery cell or between the resin layer and the module case. Fig. 8 schematically shows a case where an insulating layer 40 is formed between the
In another example of the present application, the present application relates to a method for manufacturing a battery module, such as the battery module described above.
The manufacturing method of the present application may include the steps of: injecting a resin composition into the module case; receiving a battery cell in a module case; and curing the resin composition to form a resin layer.
The order of the step of injecting the resin composition into the module case and the step of accommodating the battery cells in the module case is not particularly limited. For example, the resin composition may be first injected into the module case and then the battery cell may be accommodated in this state, or the battery cell may be first accommodated in the module case and then the resin composition may be injected therein.
As the resin composition, the above resin composition can be used.
The method of injecting the resin composition into the module case is not particularly limited, and a known method may be applied. For example, the resin composition may be injected by pouring the resin composition into an opening of the module case, or a method of injecting the resin composition through the above-described injection port formed on the module case, a method of applying the resin composition to both the battery cell and the battery module, or the like may be applied. For proper fixation, the injection process may also be performed while continuously vibrating the battery module or the battery cell.
The manner of accommodating the battery cells in the module case into which the resin composition is injected or in the module case before the injection of the composition is not particularly limited.
The accommodation of the battery cells may be performed by arranging the battery cells at appropriate positions in the module case in consideration of desired arrangement and the like. Further, when a cartridge structure is present, this step may be performed by disposing the battery cells at appropriate positions of the cartridge structure or inserting the cartridge structure with the battery cells positioned therein into the module case.
After the battery cells are accommodated therein, the adhesion between the battery cells or the adhesion between the battery cells and the module case may be achieved by curing the injected resin composition. The manner of curing the resin composition is not particularly limited. In one example, when the composition is used, the resin composition may be cured by a method of maintaining the resin composition at room temperature for a predetermined time (about 24 hours). Curing can also be accelerated by applying heat for a time and at a level that does not compromise the thermal stability of the unit. For example, by applying heat at a temperature of less than 60 ℃ (more specifically, in the range of about 30 ℃ to 50 ℃) before curing or during the curing process, or before housing the battery cell or during the housing process, the takt time may be reduced and the workability may be improved. As described above, the cured product capable of achieving the adhesion between the battery cells or between the battery cells and the module case may have a conversion rate of at least 80% or more.
In another example of the present application, the present application relates to a battery pack, for example, a battery pack including two or more battery modules as described above. In the battery pack, the battery modules may be electrically connected to each other. A method of electrically connecting two or more battery modules to constitute a battery pack is not particularly limited, and all known methods may be applied thereto.
The present application also relates to a device comprising a battery module or battery pack. Examples of such a device may include, but are not limited to, automobiles such as electric vehicles, and may be a device for all applications that require a secondary battery as electric power. In addition, a method of constructing an automobile using the battery module or the battery pack is not particularly limited, and general methods known in the art may be applied.
Advantageous effects
According to an example of the present application, there is provided a resin composition: which can have excellent injection workability to the battery module and prevent overload of an injection apparatus by exhibiting a load value and a load change rate of the reference resin composition. In addition, the composition has excellent insulation, heat dissipation and adhesion after curing.
Drawings
Fig. 1 illustrates an exemplary mixing machine that may be applied in the present application.
Fig. 2 shows an exemplary module housing that can be applied in the present application.
Fig. 3 schematically shows a form in which the battery cells are accommodated in the module case.
Fig. 4 schematically illustrates an exemplary base plate having an injection hole and a viewing hole formed therein.
Fig. 5 and 6 schematically illustrate exemplary battery bags that may be used as battery cells.
Fig. 7 and 8 schematically illustrate the structure of an exemplary battery module.
Fig. 9 is a photograph of an exemplary mixing machine.
FIG. 10 is a photograph of an exemplary static mixer applied to a mixing machine.
Detailed Description
Hereinafter, the resin composition of the present application will be described with reference to examples and comparative examples, but the scope of the present application is not limited to the following ranges.
Evaluation method
1. viscosity/TI
The viscosity was measured using A Rheometer (ARES) at room temperature and a shear rate of 0.01/sec to 10.0/sec. The viscosity mentioned in the examples is the viscosity at the point of a shear rate of 2.5/sec, wherein TI (thixotropic index) can be determined by the ratio of the viscosity at the point of a shear rate of 0.25/sec to the viscosity at the point of a shear rate of 2.5/sec.
2. Load value and load rate of change
As shown in fig. 1, the load value (kgf) of the resin composition was measured using a mixing
In the mixing machine constructed as shown in fig. 1, as the
In the configuration shown in fig. 1, TA (texture analyzer) is applied as the pressurizing means 3, 3a, 3 b.
After charging the main resin into either of the two
As for the initial load value (Li), the main resin and the curing agent were injected into the two
With respect to the elapsed load value (Lf), the main resin and the curing agent were injected into the
The load change rate (Lf/Li) can be determined via the ratio of the initial load value (Li) measured immediately after mixing the main resin and the curing agent to the elapsed load value (Lf) measured at 3 minutes after mixing the main resin and the curing agent.
3. Workability
When the fill time for dispensing was within 3 minutes and there was no overflow in the fixture made by dispensing, it is denoted as O; when the filling time for dispensing exceeds 3 minutes, or when overflow occurs in the jig manufactured by dispensing, it is denoted as X.
4. Load of equipment
When the value of the load with time (kgf) measured at 3 minutes after mixing the main resin and the curing agent exceeds 50kgf, when deformation of the device material itself is caused, for example, when occurrence of warpage in the device material is caused, or when noise is generated in the device, X is expressed, if not applicable, O is expressed.
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