Panel and battery pack for lithium secondary batteries comprising the same

Abstract

The present invention relates to a panel for a battery pack for a lithium secondary battery, the panel comprising a composite sheet comprising a substrate comprising a fibrous material and a first thermoplastic resin impregnated in the substrate. The panel further comprises a fire-retardant sheet arranged on the composite sheet and comprising a second thermoplastic resin, a first fire-retardant agent, and a second fire-retardant agent. The first fire-retardant agent comprises a halogen-based fire-retardant agent, a phosphorus-based fire-retardant agent, an inorganic fire-retardant agent, or any combination thereof. The second fire-retardant agent comprises expandable graphite.

Description

Technical Field

[0001] The present invention relates to a panel and a battery pack for lithium secondary batteries including the panel. Background Technology

[0002] As electric vehicles become heavier, their energy efficiency decreases and fuel economy declines. Lithium-ion batteries can be considered a solution to energy consumption problems and carbon reduction, but they weigh approximately 250 kg, making weight reduction a crucial task.

[0003] The battery pack casing (which houses multiple battery modules) must be robust enough to protect the batteries from various external factors during driving without significantly affecting the vehicle's weight. Various methods are being investigated to address this issue.

[0004] The protective panel located at the bottom of the battery pack casing is a component that protects the battery cooling channels and the battery itself. Currently, SMC (sheet molding compound) is being used in the panel. SMC is a composite material made of unsaturated polyester as a thermosetting resin and reinforcing fibers. SMC has a specific gravity of 1.8 to 2.1, which limits weight reduction, and because it uses thermosetting resins, it cannot be recycled, thus failing to meet carbon reduction regulations. Summary of the Invention

[0005] The various aspects disclosed herein provide a panel and a battery pack for a lithium secondary battery including the panel, the panel contributing to weight reduction due to its low specific gravity.

[0006] Another aspect disclosed herein provides a recyclable panel and a battery pack for a lithium secondary battery including the panel.

[0007] Another aspect disclosed herein provides a panel capable of protecting internal components of a battery pack from various external impacts, and a battery pack for a lithium secondary battery including the panel.

[0008] The aspects are not limited to those described above. The aspects should be clearly understood through the following description and implemented by the means described in the claims and combinations thereof.

[0009] Various aspects may provide a panel comprising a composite sheet, the composite sheet comprising a substrate comprising a fibrous material and a first thermoplastic resin impregnated therein. The panel may also include a flame-retardant sheet disposed on the composite sheet and comprising a second thermoplastic resin, a first flame retardant, and a second flame retardant.

[0010] The first flame retardant may include halogen-based flame retardants, phosphorus-based flame retardants, inorganic flame retardants, or any combination thereof.

[0011] The second flame retardant may include expandable graphite.

[0012] The substrate can be a fabric of fibrous material arranged along the warp and weft directions.

[0013] The fiber material may include synthetic fibers, natural fibers, inorganic fibers, or any combination thereof.

[0014] The fineness of the fiber material can be from 450 tex to 600 tex.

[0015] The first thermoplastic resin may include polyethylene, polypropylene, polyamide, acrylonitrile-butadiene-styrene, polycarbonate, polyethylene terephthalate, polyurethane, or any combination thereof.

[0016] The composite sheet may comprise a substrate and a first thermoplastic resin in a weight ratio of 1:1.2 to 1:1.4.

[0017] The composite sheet may include a plurality of substrates arranged in a stacked configuration and a first thermoplastic resin impregnated in the plurality of substrates.

[0018] The thickness of the composite material can be from 0.8 mm to 1.6 mm.

[0019] The second thermoplastic resin may include polyethylene, polypropylene, polyamide, acrylonitrile-butadiene-styrene, polycarbonate, polyethylene terephthalate, polyurethane, or any combination thereof.

[0020] The flame-retardant sheet material may include 30% to 60% by weight of a second thermoplastic resin, 20% to 50% by weight of a first flame retardant, and 10% to 20% by weight of a second flame retardant.

[0021] The thickness of the flame-retardant sheet can be from 0.4 mm to 0.8 mm.

[0022] The specific gravity of the panel, as measured according to ISO 1183-1, can be between 0.9 and 1.5.

[0023] The panel can absorb shock energy of 30 J or more, as measured according to ISO 6603-2.

[0024] Based on panels that have been flame-treated at 1100°C to 1300°C, perforation may occur after 5 minutes.

[0025] The panel has a tensile strength of 20 MPa to 90 MPa as measured according to ISO 527, a flexural strength of 30 MPa to 90 MPa as measured according to ISO 178, and a flexural modulus of 800 MPa to 2500 MPa.

[0026] Another embodiment of the present invention provides a battery pack including a lithium secondary battery and a housing configured to house the lithium secondary battery, wherein at least one surface of the housing includes a panel as described above. Attached Figure Description

[0027] The various aspects are described in detail below with reference to specific embodiments shown in the accompanying drawings, which are given by way of illustration only and therefore do not limit the scope of the invention, wherein: Figure 1 The housing of a battery pack according to an embodiment of the present invention is shown; Figure 2 A panel is shown according to an embodiment of the present invention; Figure 3 A composite sheet material according to an embodiment of the present invention is shown; and Figure 4 A composite sheet material according to an embodiment of the present invention is shown. Detailed Implementation

[0028] The above and other aspects, features, and advantages of the present invention should be more clearly understood through the following embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed herein, but can be modified in various forms. These embodiments are provided to fully illustrate the invention and to adequately convey its spirit to those skilled in the art.

[0029] Throughout these figures, the same reference numerals will refer to the same or similar elements. For clarity of the invention, the dimensions of the structures are depicted as larger than their actual size. It should be understood that although terms such as "first," "second," etc., may be used herein to describe various elements, these elements are not limited by these terms. These terms are used only to distinguish one element from another. For example, a "first" element discussed below may be referred to as a "second" element without departing from the scope of the invention. Similarly, a "second" element may also be referred to as a "first" element. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise.

[0030] It should be further understood that when the terms "comprising," "including," "having," etc., are used in this specification, they indicate the presence of the stated features, values, steps, operations, elements, components, or combinations thereof, but do not exclude the presence or addition of one or more other features, values, steps, operations, elements, components, or combinations thereof. Additionally, it should be understood that when an element such as a layer, film, region, or plate is referred to as being "on top of" another element, it may be directly on top of the other element, or there may be intermediate elements between them. Similarly, when an element such as a layer, film, region, or plate is referred to as being "below" another element, it may be directly below the other element, or there may be intermediate elements between them.

[0031] Unless otherwise stated, all figures, values, and / or expressions used herein to represent the amounts of components, reaction conditions, polymer compositions, and mixtures are considered approximations that include, among other things, the various uncertainties inherent in the measurement that affect the acquisition of these values, and are therefore to be understood as being modified in all cases by the term "about". Furthermore, when numerical ranges are disclosed in this specification, the ranges are continuous and include all values ​​from the minimum to the maximum of the range, unless otherwise stated. Additionally, when such ranges involve integer values, all integers from the minimum to the maximum are included, unless otherwise stated.

[0032] When the components, units, controllers, devices, elements, instruments, etc. of the present invention are described as having a purpose or performing an operation or function, the components, units, controllers, devices, elements, instruments, etc. herein should be considered as "configured" to satisfy that purpose or perform that operation or function. Each component, unit, controller, device, element, instrument, etc. may individually embody or include a processor and memory (e.g., a non-volatile computer-readable medium) as part of the instrument.

[0033] Figure 1 A battery pack housing 10 is shown. The housing 10 may include a casing 11 configured to house the battery pack internally and a cover 12 configured to cover the casing 11. At least one surface of the housing 10 may include a panel. For example, in one example, the lower surface 111 of the casing 11 may include a panel.

[0034] Figure 2 Panel 20 is shown. Panel 20 may include composite panel 100 and flame-retardant panel 200 disposed on composite panel 100.

[0035] Figure 3 A composite sheet 100 according to one embodiment is shown. The composite sheet 100 may include a substrate 110 and a first thermoplastic resin 120 impregnating the substrate 110.

[0036] Figure 4 A composite sheet 100 according to another embodiment is shown. The composite sheet 100 may include a substrate 110, a first thermoplastic resin 120 impregnating the substrate 110, and a resin layer 130 formed on at least one surface of the substrate 110 and including the first thermoplastic resin 120.

[0037] Figure 3 The composite material can be configured such that the thickness of the substrate 110 is the same as the thickness of the composite material 100 and the substrate 110 is impregnated with a first thermoplastic resin 120. Figure 4 The composite material can be configured such that the thickness of the substrate 110 is less than the thickness of the composite material 100, the substrate 110 is impregnated with a first thermoplastic resin 120, and the remaining first thermoplastic resin 120 after impregnation forms a resin layer 130 on at least one surface of the substrate 110. The composite material 100 can be configured such that a plurality of substrates 110 are stacked and impregnated with the first thermoplastic resin 120.

[0038] Substrate 110 may include fibrous material. Substrate 110 may include a fabric in which the fibrous material is arranged along the warp and weft directions. For example, substrate 110 may be a fabric in which the fibrous material is arranged at a density of about 10 / inch to 20 / inch along the warp and at a density of about 20 / inch to 30 / inch along the weft. The fabric may be knitted or twill. However, there are no particular limitations on the form of substrate 110, and any form may be used as long as the fibrous material is irregularly or regularly intertwined to provide a mesh structure.

[0039] The fibrous material may include synthetic fibers, natural fibers, inorganic fibers, or any combination thereof. Synthetic fibers may include polyvinyl alcohol, polyethylene terephthalate, polyethylene, polypropylene, acrylic acid, polyacrylonitrile, rayon, carbon fiber, or any combination thereof. Natural fibers may include cellulose, flax, wood fiber, or any combination thereof. Inorganic fibers may include glass fiber, rock wool, basalt fiber, or any combination thereof. In one example, the fibrous material includes glass fiber. For example, glass fiber may be long fibers with a length of approximately 1 mm to 50 mm.

[0040] The fineness of the fiber material can be approximately 450 tex to 600 tex. If the fineness of the fiber material is less than 450 tex, durability may deteriorate and heat resistance may decrease. On the other hand, if the fineness of the fiber material exceeds 600 tex, the panel 20 may become heavier and effective heat dissipation may become difficult.

[0041] The first thermoplastic resin 120 may include polyethylene, polypropylene, polyamide, acrylonitrile-butadiene-styrene, polycarbonate, polyethylene terephthalate, polyurethane, or any combination thereof. In one example, the first thermoplastic resin 120 includes polyethylene or polypropylene. Unlike conventional panels that use thermosetting resins, the panel 20 according to the invention may include a recyclable first thermoplastic resin 120.

[0042] The composite panel 100 may comprise a substrate 110 and a first thermoplastic resin 120 in a weight ratio of approximately 1:1.2 to 1:1.4. If the weight ratio is less than 1:1.2, the amount of the first thermoplastic resin 120 is lower, and therefore the adhesive strength and dimensional stability of the composite panel 100 may be reduced, and its thermal and chemical stability may deteriorate. On the other hand, if the weight ratio exceeds 1:1.4, the panel 20 may become heavier and its flexibility may decrease, resulting in poor processability.

[0043] The thickness of the composite plate 100 can be approximately 0.8 mm to 1.6 mm. If the thickness of the composite plate 100 is less than 0.8 mm, it may not be able to protect the lithium secondary battery inside the battery pack from external impacts, while if the thickness of the composite plate 100 exceeds 1.6 mm, it may be detrimental to weight reduction.

[0044] The flame-retardant sheet 200 may include a second thermoplastic resin, a first flame retardant, and a second flame retardant. The flame-retardant sheet 200 may further include fillers as needed.

[0045] The second thermoplastic resin may include polyethylene, polypropylene, polyamide, acrylonitrile-butadiene-styrene, polycarbonate, polyethylene terephthalate, polyurethane, or any combination thereof. The second thermoplastic resin may be the same as or different from the first thermoplastic resin 120.

[0046] The first flame retardant may include halogen-based flame retardants, phosphorus-based flame retardants, inorganic flame retardants, or any combination thereof.

[0047] Halogen-based flame retardants may include brominated flame retardants, chlorinated flame retardants, or combinations thereof. Brominated flame retardants may include tribromophenoxyethylene, tetrabromobisphenol A, or combinations thereof. Chlorinated flame retardants may include chlorinated paraffin, chlorinated polyethylene, aliphatic chlorinated flame retardants, or any combination thereof.

[0048] Phosphorus-based flame retardants may include at least one functional group of phosphate esters, phosphonates, hypophosphonates, phosphonium oxides or phosphazenes, and may include phosphorus / halogen flame retardants, phosphorus / nitrogen flame retardants, etc.

[0049] Inorganic flame retardants may include aluminum hydroxide (Al(OH)3), antimony oxide (Sb2O3), magnesium hydroxide (Mg(OH)2), or any combination thereof.

[0050] The second flame retardant can include expandable graphite. Expandable graphite forms a solid layer of flame retardant, while the expanded carbon layer acts as an insulating layer to prevent heat transfer. Expandable graphite can be used as a non-halogenated, low-flame, environmentally friendly flame retardant. When expandable graphite expands due to heat, it exhibits excellent thermal insulation properties in the direction perpendicular to the plane of the layer. Expandable graphite has the advantages of being non-toxic, lightweight, halogen-free, insoluble in water, and not producing toxic gases.

[0051] The filler may include calcium carbonate, silicate, clay, glass fiber, carbon fiber, or any combination thereof. Glass fiber is included as a filler.

[0052] The flame-retardant sheet 200 may include approximately 30% to 60% by weight of a second thermoplastic resin, approximately 20% to 50% by weight of a first flame retardant, and approximately 10% to 20% by weight of a second flame retardant. The flame-retardant sheet 200 may also include approximately 30% to 60% by weight of a second thermoplastic resin, approximately 20% to 50% by weight of the first flame retardant, approximately 10% to 20% by weight of the second flame retardant, and approximately 5% to 15% by weight of filler. When the amount of each component of the flame-retardant sheet 200 falls within the above-mentioned range, the flame retardancy and physical properties of the panel 20 can be improved.

[0053] The thickness of the flame-retardant sheet 200 can be approximately 0.4 mm to 0.8 mm. If the thickness of the flame-retardant sheet 200 is less than 0.4 mm, the flame retardancy may be compromised, while if the thickness of the flame-retardant sheet 200 exceeds 0.8 mm, it may be detrimental to weight reduction.

[0054] Panel 20, meeting the above conditions, has a specific gravity of approximately 0.9 to 1.5, as measured according to ISO 1183-1. Panel 20 can help reduce the weight of the battery pack.

[0055] Furthermore, the impact absorption energy of panel 20, measured according to ISO 6603-2, can be approximately 30 J or greater. There is no particular upper limit to the impact absorption energy; it can be 200 J or less, 150 J or less, or 100 J or less. The tensile strength of panel 20, measured according to ISO 527, can be approximately 20 MPa to 90 MPa; the flexural strength, measured according to ISO 178, can be approximately 30 MPa to 90 MPa; and the flexural modulus can be approximately 800 MPa to 2500 MPa. The casing incorporating panel 20 protects the internal lithium-ion battery.

[0056] Based on the panel 20, which has been flame-treated at 1100°C to 1300°C, perforation may occur after approximately 5 minutes. There is no particular upper limit to the perforation time; it can be 1 hour or less, 50 minutes or less, 40 minutes or less, or 30 minutes or less. The housing on which the panel 20 is applied is heat-resistant and can protect the internal lithium secondary battery.

[0057] The following examples can provide a better understanding of the invention, but these examples should not be construed as limiting the invention.

[0058] Example 1 A substrate woven from glass fibers with a fineness of approximately 600 tex was prepared. A composite board was obtained by impregnating the substrate with polyethylene and then drying it at room temperature. Specifically, a polyethylene sheet was laminated onto both surfaces of the substrate, followed by pressing at approximately 200°C to 240°C under a pressure of approximately 7.0 kPa to 9.0 kPa to impregnate the substrate with polyethylene. The weight ratios of the substrate and polyethylene in the composite board are shown in Table 1 below. The thickness of the composite board is approximately 1.2 mm.

[0059] Flame-retardant sheets were prepared by mixing a second thermoplastic resin, a first flame retardant, a second flame retardant, and fillers in the amounts shown in Table 1, followed by extrusion into sheets. The second thermoplastic resin was polypropylene, and the filler was glass fiber. The thickness of the flame-retardant sheets was approximately 0.6 mm.

[0060] A panel is made by placing flame-retardant sheets on a composite sheet and then pressing them together.

[0061] Example 2 The panel was manufactured in the same manner as in Example 1, except that the weight ratio of the substrate to polyethylene in the composite panel was changed, as shown in Table 1.

[0062] Example 3 The panel is manufactured in the same manner as in Example 1, except that a substrate woven from glass fibers with a fineness of approximately 450 tex is used.

[0063] Comparative Example 1 and Comparative Example 2 The panels were manufactured in the same manner as in Example 1, except that a substrate woven from glass fibers with a fineness of approximately 300 tex was used and the composition of the flame-retardant material was changed.

[0064] Table 1 The specific gravity, impact energy absorption, and flame-induced perforation time of the panels from Examples 1 to 3, as well as Comparative Examples 1 and 2, are measured as follows. The results are shown in Table 2 below.

[0065] [proportion] 1) Testing standard: ISO 1183-1 2) Test method: Among the immersion method, liquid specific gravity bottle method and titration method (electronic specific gravity meter principle), the immersion method is used to measure specific gravity.

[0066] - Measure the apparent mass of the specimen in air (m S,A ) - Measure the apparent mass (m) of the specimen in the liquid (water). S,IL ) - Specimen density (ρ) S )= (m S,A x ρ IL ) / (m S,A - m S,IL ), where ρ IL It is the density of the liquid (water).

[0067] - Specific gravity of the specimen (S) = ρ S / ρ IL - Determine the average value after three measurements. [Impact energy absorption] 1) Testing standard: ISO 6603-2 2) Test method: Using a lubricated impact rod, strike the center of the specimen surface perpendicularly at a constant speed until perforation occurs, and record the force-deflection curve. 3) Test conditions: Test mass is 20 kg, test speed is 4.4 m / s, drop weight: 20 mm semi-circular weight. [Time of flame-induced perforation] 1) Testing Method - Ignition source: Butane gas spray gun - During the evaluation process, temperature is measured by installing temperature measuring devices before and after the heating point of the specimen. - Flame temperature: >1000°C - Flame distance: 7 cm 2) Judgment: Measure the time when the perforation occurs on the back of the specimen. Table 2 Referring to Table 2, Examples 1 to 3 have lower specific gravity, which can reduce the weight of the battery pack. In addition, the impact energy absorption and flame-induced perforation occurrence time are better than those of Comparative Examples 1 and 2, which can effectively protect the lithium secondary battery inside the battery pack.

[0068] It is evident from the above that a panel that helps reduce weight due to its low specific gravity and a battery pack for lithium secondary batteries including the panel can be obtained.

[0069] It is possible to obtain recyclable panels and battery packs for lithium secondary batteries that include the panels.

[0070] It is possible to obtain a panel that can protect the internal components of the battery pack from various external impacts, as well as a battery pack for lithium secondary batteries including the panel.

[0071] The effects of this invention are not limited to those described above. It should be understood that the effects of this invention include all effects that can be inferred from the description of this invention.

[0072] As described above, although embodiments have been described, those skilled in the art will understand that various modifications and changes can be made to the above embodiments. For example, suitable results can be obtained even if the described techniques are performed in a different order than the described methods and / or even if the described components (e.g., systems, structures, devices, circuits, etc.) are linked or combined in a different form than the described methods, or are replaced or substituted by other components or equivalents. Therefore, other embodiments, other examples, and equivalents of the claims are also within the scope of the appended claims.

Claims

1. A panel comprising: A composite sheet comprising a substrate and a first thermoplastic resin impregnated in the substrate, the substrate comprising a fibrous material; and A flame-retardant board, wherein the flame-retardant board is disposed on a composite board and comprises a second thermoplastic resin, a first flame retardant, and a second flame retardant. The first flame retardant includes halogen-based flame retardants, phosphorus-based flame retardants, inorganic flame retardants, or any combination thereof; The second flame retardant includes expandable graphite.

2. The panel according to claim 1, wherein, The substrate is a fabric of fibrous material arranged along the warp and weft directions.

3. The panel according to claim 1, wherein, The fiber material includes synthetic fibers, natural fibers, inorganic fibers, or any combination thereof.

4. The panel according to claim 1, wherein, The fineness of the fiber material is 450 tex to 600 tex.

5. The panel according to claim 1, wherein, The first thermoplastic resin includes polyethylene, polypropylene, polyamide, acrylonitrile-butadiene-styrene, polycarbonate, polyethylene terephthalate, polyurethane, or any combination thereof.

6. The panel according to claim 1, wherein, The composite sheet comprises a substrate and a first thermoplastic resin in a weight ratio of 1:1.2 to 1:1.

4.

7. The panel according to claim 1, wherein, The composite sheet comprises a plurality of substrates arranged in a stacked configuration and a first thermoplastic resin impregnated in the plurality of substrates.

8. The panel according to claim 1, wherein, The thickness of the composite material is 0.8 mm to 1.6 mm.

9. The panel according to claim 1, wherein, The second thermoplastic resin includes polyethylene, polypropylene, polyamide, acrylonitrile-butadiene-styrene, polycarbonate, polyethylene terephthalate, polyurethane, or any combination thereof.

10. The panel according to claim 1, wherein, The flame-retardant sheet comprises 30% to 60% by weight of a second thermoplastic resin, 20% to 50% by weight of a first flame retardant, and 10% to 20% by weight of a second flame retardant.

11. The panel according to claim 1, wherein, The thickness of the flame-retardant sheet is 0.4 mm to 0.8 mm.

12. The panel according to claim 1, wherein, The panel has a specific gravity of 0.9 to 1.5 as measured according to ISO 1183-1.

13. The panel according to claim 1, wherein, The panel absorbs an impact energy of 30 J or more, as measured according to ISO 6603-2.

14. The panel according to claim 1, wherein, When the panel is flame-treated at 1100°C to 1300°C, perforation occurs after 5 minutes.

15. The panel according to claim 1, wherein, The panel has a tensile strength of 20 MPa to 90 MPa as measured according to ISO 527, a flexural strength of 30 MPa to 90 MPa as measured according to ISO 178, and a flexural modulus of 800 MPa to 2500 MPa.

16. A battery pack comprising: Lithium secondary batteries; and The housing is configured to house a lithium secondary battery. Wherein, at least one surface of the housing includes a panel, the panel comprising: Composite sheet, the composite sheet comprising a substrate and a first thermoplastic resin impregnated in the substrate, the substrate comprising a fibrous material; and A flame-retardant board, wherein the flame-retardant board is disposed on a composite board and comprises a second thermoplastic resin, a first flame retardant, and a second flame retardant. The first flame retardant includes halogen-based flame retardants, phosphorus-based flame retardants, inorganic flame retardants, or any combination thereof. The second flame retardant includes expandable graphite.

17. The battery pack according to claim 16, wherein, The substrate is a fabric of fibrous material arranged along the warp and weft directions.

18. The battery pack according to claim 16, wherein, The fiber material includes synthetic fibers, natural fibers, inorganic fibers, or any combination thereof.

19. The battery pack according to claim 16, wherein, The composite sheet comprises a plurality of substrates arranged in a stacked configuration and a first thermoplastic resin impregnated in the plurality of substrates.

20. The battery pack according to claim 16, wherein, The first thermoplastic resin and the second thermoplastic resin include polyethylene, polypropylene, polyamide, acrylonitrile-butadiene-styrene, polycarbonate, polyethylene terephthalate, polyurethane, or any combination thereof.

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