KR102225637B1 - Composite material for battery pack case - Google Patents

Abstract

Composite materials for battery pack cases are provided. The composite material for the battery pack case includes a flame retardant layer and a metal layer disposed on the flame retardant layer. The metal layer contains silver (Ag) and has a thickness of 5 µm to 10 µm.
The flame-retardant layer includes a laminate in which fibrous layers including continuous fibers oriented in a plane are laminated and a flame-retardant resin substrate impregnated in the laminate. The fibrous layers are laminated in the thickness direction of the flame retardant layer so that the oriented surfaces of the continuous fibers face each other.

Description

Composite material for battery pack case{COMPOSITE MATERIAL FOR BATTERY PACK CASE}

The present invention relates to a composite material for a battery pack case.

Lithium-ion secondary batteries are used as power sources for portable electronic devices, electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and energy storage devices. Lithium-ion secondary batteries are commercialized in the form of a battery pack in which a battery cell, a protection circuit, and a protection device are set in a case.

Lithium-ion secondary batteries have a problem in that they explode or generate fire due to generation of combustible gas due to a decomposition reaction of an electrolyte, combustible gas due to a reaction between an electrolyte and an electrode, and oxygen due to decomposition of a positive electrode.

Electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, energy storage devices, and the like, require a large amount of power to be supplied, so the risk of a secondary explosion is very high.

Meanwhile, since electronic components are embedded in the battery pack, electromagnetic waves are generated therefrom. Electromagnetic waves radiated or conducted from the battery pack may impair the function of other devices, cause infertility, etc. by causing abnormalities in the reproductive organs of the user, or damage to the eyeball, causing cataracts, etc., and may cause headaches. Sometimes it does.

The present invention is to provide a composite material for a battery pack case that can improve the mechanical properties and safety of the battery pack.

In addition, the present invention is to provide a composite material for a battery pack case having electromagnetic wave shielding performance.

However, the technical problem to be achieved by the present invention is not limited to the problems mentioned above, and other problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

The composite material for a battery pack case according to the present invention includes a flame retardant layer and a metal layer disposed on the flame retardant layer. The metal layer contains silver (Ag) and has a thickness of 0.5 µm to 10 µm.

The flame retardant layer includes a laminate in which fibrous layers including continuous fibers oriented in a plane are laminated and a flame-retardant resin substrate impregnated in the laminate. The fibrous layers are laminated in the thickness direction of the flame retardant layer so that the oriented surfaces of the continuous fibers face each other.

The composite material for a battery pack case according to the present invention has an electromagnetic wave shielding performance of 85 dB or more in a frequency band of 30 MHz to 1.5 GHz.

The composite material for a battery pack case according to the present invention can secure flame resistance through a flame retardant layer.

In the discontinuous fiber composite material, compared to the continuous fiber composite material, since more resin substrates may be interposed between discontinuous fibers such as short fibers, there are more spaces and interfaces in which the resin substrate may be burned.

The flame retardant layer includes a laminate in which fibrous layers including continuous fibers oriented in a plane are laminated and a flame-retardant resin substrate impregnated in the laminate. Since the fiber layers are stacked in the thickness direction of the flame-retardant layer so that the oriented surfaces of the continuous fibers face each other, when a flame is applied in the thickness direction of the composite material for the battery pack case, the flame-retardant layer is the battery pack compared to the discontinuous fiber composite material. Since the flame propagation path in the thickness direction of the case composite material can be reduced, improved flame retardant performance can be provided to the composite material for the battery pack case.

The composite material for a battery pack case according to the present invention can exhibit an electromagnetic wave shielding performance of 85 dB or more in a frequency band of 30 MHz to 1.5 GHz through a metal layer containing silver (Ag) and having a thickness of 0.5 µm to 10 µm.

In addition, since the composite material for a battery pack case according to the present invention can reinforce the reinforcing part through the design of the fiber layers, it is mechanical for protecting the battery cell compared to the discontinuous fiber composite material in which the discontinuous fibers are arranged in a negative direction. It has an advantageous advantage in improving physical properties.

The effects of the present invention are not limited to the above-mentioned effects, and other effects that are not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 is a schematic cross-sectional view of an example of a composite material for a battery pack case, and shows that a metal layer is directly bonded to a flame retardant layer.
FIG. 2 is a schematic diagram of an example of the flame-retardant layer of FIG. 1, and shows that a laminate of continuous fibers is impregnated with a flame-retardant resin.
3 is a schematic diagram of an example of the flame-retardant layer of FIG. 1, and shows a laminate of woven fabrics of continuous fibers impregnated with a flame-retardant resin.
FIG. 4 is a schematic diagram of an example of the flame retardant layer of FIG. 1, and shows a laminate of non-crimp reinforcing fiber (NCF) fabrics impregnated with a flame-retardant resin.
5 is a schematic diagram of an example of the flame retardant layer of FIG. 1, and shows a laminate of UD prepregs.
6 is a schematic diagram of an example of the flame retardant layer of FIG. 1, and shows a laminate of raw prepregs.
7 is a schematic cross-sectional view of an example of a composite material for a battery pack case, showing that a bonding layer is interposed on the flame retardant layer and the metal layer.
8 is a schematic cross-sectional view of an example of a composite material for a battery pack case, and shows that a flame-retardant porous layer is interposed between fiber layers.

Advantages and features of the invention, and a method of achieving them will become apparent with reference to embodiments and experimental examples to be described later in detail together with the accompanying drawings. It should be noted that the accompanying drawings are only for easily understanding the spirit of the technology disclosed in the present specification, and should not be construed as limiting the spirit of the technology by the accompanying drawings.

In addition, the invention is not limited to the content disclosed below, but may be implemented in various forms, and the content disclosed below makes the disclosure of the invention complete, and the invention is for those of ordinary skill in the art to which the invention pertains. It is provided to fully inform the scope of the invention, and the invention is only defined by the scope of the claims.

If it is determined that a detailed description of a related known technology may obscure the gist of the technology, the detailed description may be omitted. The same reference numerals refer to the same elements throughout the specification. In the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity of description.

Although the first, second, and the like are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are only used to distinguish one component from another component, and unless otherwise stated, the first component may be the second component.

Throughout the specification, unless otherwise specified, each component may be singular or plural. Throughout the specification, when a part refers to "including" or "having" a certain component, this does not exclude other components, but further includes other components, unless specifically stated to the contrary. It means something that can be included.

Throughout the specification, when referred to as "A and/or B", it means A, B or A and B, unless otherwise specified, and when referred to as "C to D", it means that a special opposite description is Unless there is one, it means that it is C or more and D or less.

Spatially relative terms "below", "beneath", "lower", "above", "upper", etc. It may be used to easily describe the correlation between the device or components and other devices or components. Spatially relative terms should be understood as terms including different directions of the device during use or operation in addition to the directions shown in the drawings.

1 is a schematic cross-sectional view of an example of a composite material 100 for a battery pack case, and shows that the metal layer 20 is directly bonded to the flame retardant layer 10. 2 to 6 are schematic views of the flame retardant layer 10 of FIG. 1.

1 to 6, the composite material 100 for a battery pack case includes a flame retardant layer 10 and a metal layer 20 disposed on the flame retardant layer 10.

The flame-retardant layer 10 includes a laminate in which fibrous layers are laminated and a flame-retardant resin substrate impregnated in the laminate of fibrous layers. Each of the fibrous layers includes continuous fibers oriented in-plane, and is laminated in the thickness direction of the flame retardant layer 10 or the thickness direction of the composite material 100 for a battery pack case so that the oriented surfaces of the continuous fibers face each other. The fraction of continuous fibers in the flame retardant layer 10 is 35 vol% to 60 vol%.

The laminated structure between the fibrous layers may be designed according to mechanical properties required for the composite material 100 for a battery pack case. The laminated structure between the fibrous layers may be designed to be anisotropic for reinforcing rigidity. However, in order to limit the problem of unintended post-deformation, it is preferable that the stacked structure in the thickness direction of the composite material 100 for the battery pack case is a symmetrical structure.

The flame-retardant layer 10 is an array of continuous fibers in which continuous fibers 1 are oriented in one direction (F1, F2, F3 in FIG. 2), a woven fabric of continuous fibers in which continuous fibers are woven (WF1 in FIG. 3, HP-RTM (HIGH-PRESSURE RESIN TRANSFER MOLDING) is impregnated with flame-retardant resin in a laminate in which at least one fiber layer of WF2) and non-bending reinforcing fiber fabric fabrics (NCF1, NCF2 in Fig. 4) are laminated, and then cured. ) Can be obtained by the construction method.

2 to 4 show the flame retardant layer 10 obtained by using the HP-RTM (HIGH-PRESSURE RESIN TRANSFER MOLDING) method. Although a structure in which two layers are stacked is illustrated in FIGS. 2 to 4 by way of example, the number of fibrous layers constituting the flame retardant layer 10 is not limited to that shown.

2 is a schematic diagram of an example of the flame-retardant layer of FIG. 1, in which a flame-retardant resin substrate (P) is impregnated into a laminate of arrays (F1, F2, F3) of continuous fibers (1) oriented in one direction. Shows. As shown in FIG. 2, the fibrous layers may be arrays (F1, F2, F3) of continuous fibers 1 in which the continuous fibers 1 are oriented in one direction, respectively. As shown in FIG. 2, the one-way orientation direction of the continuous fibers 1 of each of the fibrous layers F1, F2, and F3 may be the same.

3 is a schematic diagram of an example of the flame-retardant layer 10 of FIG. 1, and a flame-retardant resin in a laminate (WF) of woven fabrics (WF1, WF2) of the weft (1) and warp (2) made of continuous fibers The substrate P is impregnated. 3, the flame-retardant layer 10 is a flame-retardant resin base material (P) on a laminate (WF) in which woven fabrics (WF1, WF2) are woven by crossing the weft (1) and the warp (2) upward and downward. ) Can also be obtained by impregnating.

4 is a schematic diagram of an example of the flame retardant layer 10 of FIG. 1, and a laminate of non-crimp fabric (NCF) fabrics (NCF1, NCF2) of continuous fibers (1, 2) It shows that (NCF) is impregnated with a flame-retardant resin base material (P). As shown in FIG. 4, the NCF fabrics (NCF1, NCF2), unlike the woven fabric fabrics, are arranged almost in a straight line, so that bending does not occur. Although not shown, in the NCF fabric (NCF1 NCF2), constituent fibers are stitched or bonded.

In the laminate (NCF) of the NCF fabrics (NCF1, NCF2), the orientation directions of the continuous fibers (1, 2) of each layer may be different from each other, for example, the continuous fibers (1, 2) of each layer. NCF fabrics (NCF1, NCF2) may be stacked so that the orientation direction of) is 0°/+45°/90°/-45° or 0°/90°/0°/90°. 4 shows a case where the orientation direction of the continuous fibers 1 and 2 of each layer is 0°/90°/0°/90°, but is not limited thereto.

The flame-retardant layer 10 may also be obtained by curing or laminating the laminates (UD, FP) of the UD prepregs (UD1, UD2) and/or the original prepregs (FP1, FP2).

FIG. 5 is a schematic diagram of an example of the flame retardant layer 10 of FIG. 1, and shows a stacked body UD of UD prepregs UD1 and UD2. Referring to FIG. 5, UD prepregs UD1 and UD2 have a structure in which a flame-retardant resin base material P is impregnated in a fibrous layer made of continuous fibers 1 and 2 oriented in one direction, and a flame retardant layer 10 ) May be obtained by stacking UD prepregs UD1 and UD2.

6 is a schematic diagram of an example of the flame retardant layer 10 of FIG. 1, and shows a laminate FP of the original prepregs FP1 and FP2. Referring to FIG. 6, the fabric prepregs FP1 and FP2 have a structure in which a flame-retardant resin base material is pre-impregnated into a woven fabric fabric layer or an NCF fabric fiber layer made of continuous fibers 1 and 2, respectively. The flame retardant layer 10 may be obtained by laminating woven fabric prepregs (FP1, FP2) or non-crimp reinforcing fiber fabric (non-crimp fabric; NCF) fabric prepregs (FP1, FP2).

As shown in FIGS. 4 and 5, the one-way orientation directions of the continuous fibers 1 and 2 of each layer may be alternated with each other. For example, the flame retardant layer 10 includes a first layer in which one direction of the continuous fibers 1 and 2 of each layer is a first direction and a second layer in which one direction of the continuous fibers is a second direction. The first direction and the second direction may be alternated with each other. For example, the second layer may be disposed on the first layer.

The first direction may have an angle of +θ° with respect to the reinforcement required direction, and the second direction may have an angle of -θ° with respect to the reinforcement required direction. In this case, θ° may be 1° to 44°. For example, an angle of intersection between the first and second directions may be 30° to 90°.

'Reinforcement request direction' is a predetermined direction in which strength and rigidity need to be supplemented in consideration of external force or load applied from the outside when the battery pack case is mounted on a vehicle, or when the vehicle is operated and moved after installation. Means. The direction required for reinforcement may be determined by a restraint position and an installation condition when the battery pack is mounted to a component such as a vehicle, and most principally refers to one direction in which strength and rigidity need to be supplemented.

The continuous fibers (1, 2) are made of a material with good heat resistance, for example, glass fiber, carbon fiber, aramid fiber, glass fiber and carbon fiber blend, glass fiber and aramid fiber blend, carbon fiber and aramid It may be a blend of fibers or a blend of glass fibers, carbon fibers and aramid fibers.

The flame-retardant resin base material P may be composed of a flame-retardant thermosetting plastic or a flame-retardant thermoplastic. Examples of the flame-retardant thermosetting plastic include at least one of a flame-retardant epoxy resin, a flame-retardant urethane resin, a flame-retardant phenol resin, a flame-retardant urea resin, and a flame-retardant melamine resin.

Examples of flame-retardant thermoplastic plastics include at least one of polyphenylene sulfide (PPS), flame-retardant prescription polycarbonate (PC), and flame-retardant polyamide (PA).

The flame-retardant thermosetting plastic or flame-retardant thermoplastic plastic may be prepared by adding a known flame retardant to the thermosetting plastic or thermoplastic plastic, and examples of the known flame retardant include a halogen-based flame retardant and/or a non-halogen-based flame retardant. In terms of toxicity and environmental friendliness, a non-halogen-based flame retardant may be used as a flame retardant, and examples of the non-halogen-based flame retardant include a phosphorus-based flame retardant.

The metal layer 20 includes silver (Ag) or an alloy thereof, and has a thickness of 0.5 µm to 10 µm. The metal layer 20 may provide an electromagnetic wave shielding performance of 85 dB or more in a frequency band of 30 MHz to 1.5 GHz to the composite material 100 for a battery pack case.

The metal layer 20 may be plated on the flame-retardant laminate 10 using a spray deposition method. The metal layer 20 can be obtained by repeatedly spray-depositing silver (Ag) particles on the flame-retardant laminate 10.

Silver (Ag) is a material excellent in electromagnetic wave shielding performance in the frequency band of 30 MHz to 1.5 GHz. However, as can be seen in the comparative experiment to be described later, when the thickness of the metal layer 20 is less than 0.5 μm, the electromagnetic wave shielding performance in the frequency band of 30 MHz to 1.5 GHz is less than 85 dB, which is required for the battery pack case. It is difficult to implement shielding performance.

On the other hand, when the thickness of the metal layer 20 is more than 10 μm, the composite material for the battery pack case 100 shields electromagnetic waves of 85 dB or more in the frequency band of 30 MHz to 1.5 GHz, as in the case where the thickness of the metal layer 20 is 10 μm or less. Performance can be demonstrated.

However, the composite material 100 for a battery pack case in which the thickness of the metal layer 20 is greater than 10 μm is difficult to provide a lightweight battery pack case due to an increase in weight, and the number of deposition processes for forming the metal layer 20 is reduced. There is a problem that the price competitiveness of the battery pack case is weakened due to the increase and the production cost such as material cost increases.

Examples and Comparative Examples

After producing a flame-retardant laminate of 8 UD prepregs having a thickness of 3.2 mm by hot press bonding, silver (Ag) particles were repeatedly deposited on the flame-retardant laminate by spraying to have the same thickness as in Table 1 below. A composite material for a battery pack case with a metal layer plated was obtained.

The eight UD prepregs were composed of 50 vol% of continuous glass fibers and 50 vol% of flame-retardant epoxy resin impregnated therewith, and the cross angle of the continuous glass fibers between each layer in one direction of orientation was 90°.

Experimental example

The shielding performance and weight reduction rate of the composite material for the battery pack case according to the examples and the composite material for the battery pack case according to the comparative examples were measured. Table 1 below summarizes the measurement results.

(Shielding performance evaluation)

The shielding performance of the sample was evaluated by measuring the electromagnetic wave generated by the signal generator through the sample in the sample holder by the receiver. The standard was in accordance with ASTM D4935 and the measurement frequency was 30MHz~1.5GHz.

(How to calculate weight reduction rate)

The weight was measured by making a flat plate (thickness: 3.2 mm) similar to the size of the battery pack case made of aluminum that is applied to mass-produced battery packs. The weight of the flat plate made of aluminum was taken as the weight (a).

As shown in Table 1 below, the weight (b) of the composite material for the battery pack case was calculated according to the change in the thickness of the metal layer, and the weight reduction rate was calculated as (a-b)/a (%).

Thickness of flame retardant laminate
(mm) Metal layer thickness
(μm) Shielding performance (dB) Light weight reduction rate (%) Comparative Example 1 3.2 0 0 30.741 Comparative Example 2 3.2 0.3 60 30.737 Comparative Example 3 3.2 15 85 or more 30.567 Comparative Example 4 3.2 70 85 or more 29.931 Example 1 3.2 0.5 85 or more 30.735 Example 2 3.2 5 85 or more 30.683 Example 3 3.2 10 85 or more 30.625

The composite material for a battery case according to Examples 1 to 3 had a shielding performance of 85 dB or more, and a weight reduction rate of 30% or more.

The composite material for a battery case according to Comparative Example 1 does not have a metal layer, and the composite material for a battery case according to Comparative Example 2 has a thickness of less than 0.5 μm. The composite material for a battery case according to Comparative Examples 1 and 2 had a shielding performance of less than 85dB.

The composite material for a battery case according to Comparative Examples 3 and 4 is a case in which the thickness of the metal layer is more than 10 μm, and the unit price is increased compared to the composite material for a battery case according to Examples 1 to 3, or the weight reduction rate is increased with the increase in the unit price. fell.

Although the embodiments have been described with reference to the accompanying drawings, the invention is not limited to the above embodiments, but may be manufactured in various different forms by combining the contents disclosed in each embodiment. Those skilled in the art will understand that the invention can be implemented in other specific forms without changing the technical idea or essential features. Therefore, it should be understood that the embodiments described above are illustrative and non-limiting in all respects.

1,2: continuous fiber
P: flame retardant resin substrate
10: flame retardant layer 20: metal layer
100: composite material for battery pack case

Claims (11)

A flame-retardant layer including a laminate in which fibrous layers including continuous fibers are oriented in a plane are laminated and a flame-retardant resin substrate impregnated in the laminate; And
Contains silver (Ag) and has a thickness of 0.5 µm to 10 µm, and a metal layer disposed on the flame-retardant layer; includes,
The fiber layers are laminated in the thickness direction of the flame retardant layer so that the oriented surfaces of the continuous fibers face each other,
The metal layer is directly bonded on the flame retardant layer,
The electromagnetic wave shielding performance in the frequency band of 30 MHz to 1.5 GHz is 85 dB or more.
Composite material for battery pack case. The method of claim 1,
The fiber layers are each of the continuous fibers oriented in one direction
Composite material for battery pack case. The method of claim 1,
The fibrous layers include a first layer and a second layer disposed on the first layer,
In the first layer, the continuous fibers are oriented in one direction in a first direction,
In the second layer, the continuous fibers are oriented in one direction in a second direction,
The first direction and the second direction are crossed
Composite material for battery pack case. The method of claim 1,
Each of the fiber layers is a woven fabric fabric layer in which the continuous fibers are woven
Composite material for battery pack case. The method of claim 1,
Each of the fiber layers is a non-crimp reinforcing fiber (NCF) fabric layer of continuous fibers of the continuous fibers.
Composite material for battery pack case. The method of claim 1,
The flame-retardant layer further comprises a flame-retardant porous layer interposed between the fibrous layers.
Composite material for battery pack case. The method of claim 1,
The metal layer is formed by spray deposition
Composite material for battery pack case. delete delete The method of claim 1,
The continuous fibers are composed of glass fiber, carbon fiber, or a combination of glass fiber and carbon fiber
Composite material for battery pack case. The method of claim 1,
The flame retardant layer has a fraction of the continuous fibers of 35 vol% to 60 vol%
Composite material for battery pack case.

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