Separator, method of manufacturing separator, and battery module including separator

Abstract

Disclosed examples include a separator including a polymer matrix and an endothermic flame retardant dispersed in the polymer matrix, a method of manufacturing the separator, and a battery module including the separator. The polymer matrix includes a fibrillated polymer, and the endothermic flame retardant is included in an amount ranging from about 60 wt% to about 98 wt% relative to the total weight of the spacer.

Description

Technical Field

[0001] This disclosure relates to spacers, methods of manufacturing spacers, and battery modules including spacers. Background Technology

[0002] Unlike primary batteries, which are typically non-rechargeable, secondary batteries can be charged and discharged. Low-capacity battery cells are used in small portable electronic devices (such as smartphones, feature phones, laptops, digital cameras, and camcorders), while high-capacity battery cells are widely used as drive power sources and energy storage batteries for motors in vehicles such as hybrid vehicles and electric vehicles. Such battery cells include electrode assemblies containing positive and negative electrodes, a housing for accommodating the electrode assemblies, and electrode terminals connected to the electrode assemblies. Summary of the Invention

[0003] Example embodiments of this disclosure include a spacer configured to absorb heat released in the event of a battery fire to reduce or suppress temperature rise and reduce or prevent a fire chain reaction, a method of manufacturing the spacer, and a battery module including the spacer.

[0004] However, the technical objectives to be achieved by this disclosure are not limited to those described above, and those skilled in the art will clearly understand from the following disclosure other objectives not described herein.

[0005] Example embodiments of this disclosure include a spacer comprising a polymer matrix and an endothermic flame retardant dispersed in the polymer matrix, wherein the polymer matrix comprises a fibrous polymer, and the endothermic flame retardant is included in an amount ranging from about 60 wt% to about 98 wt% relative to the total weight of the spacer.

[0006] In the example embodiment, the heat-absorbing flame retardant may be or includes an inorganic hydroxide compound.

[0007] In an example embodiment, the fibrous polymer may include at least one of polytetrafluoroethylene, cellulose nanofibers, and polycaprolactam.

[0008] In the example embodiment, the mass ratio of the heat-absorbing flame retardant to the fibrous polymer can be in the range of about 1.5 to about 49.

[0009] In the example embodiment, the fibrillation rate of the fibrillated polymer can be in the range of about 1% to about 40%.

[0010] In the example embodiment, the average diameter of the heat-absorbing flame retardant can be in the range of about 0.1 μm to about 50 μm.

[0011] In an example embodiment, the heat-absorbing flame retardant may include at least one of magnesium hydroxide, aluminum hydroxide, antimony trioxide, and antimony pentoxide.

[0012] Another exemplary embodiment of this disclosure includes a battery module comprising: a plurality of battery cells; and spacers disposed between the plurality of battery cells, wherein each of the spacers comprises a polymer matrix and an endothermic flame retardant dispersed in the polymer matrix. The polymer matrix comprises a fibrous polymer, and the endothermic flame retardant is included in an amount ranging from about 60 wt% to about 98 wt% relative to the total weight of the spacers.

[0013] In the example embodiment, the heat-absorbing flame retardant may be or includes an inorganic hydroxide compound.

[0014] In an example embodiment, the fibrous polymer may include at least one of polytetrafluoroethylene, cellulose nanofibers, and polycaprolactam.

[0015] In the example embodiment, the mass ratio of the heat-absorbing flame retardant to the fibrous polymer can be in the range of about 1.5 to about 49.

[0016] In the example embodiment, the fibrillation rate of the fibrillated polymer can be in the range of about 1% to about 40%.

[0017] In the example embodiment, the average diameter of the heat-absorbing flame retardant can be in the range of about 0.1 μm to about 50 μm.

[0018] In an example embodiment, each of the plurality of battery cells may include an electrode assembly and a conductive metal housing, the electrode assembly including a positive electrode, a negative electrode and a separator between the positive and negative electrodes, the electrode assembly being housed in the conductive metal housing.

[0019] Another exemplary embodiment of this disclosure includes a method of manufacturing a spacer, the method comprising the steps of: forming a mixture by mixing a heat-absorbing flame retardant and a polymer powder; pressing the mixture; and forming the spacer by molding the mixture, wherein the spacer comprises a polymer matrix and a heat-absorbing flame retardant dispersed in the polymer matrix. The polymer matrix comprises a fibrous polymer, and the heat-absorbing flame retardant is included in an amount ranging from about 60 wt% to about 98 wt% relative to the total weight of the spacer.

[0020] In the example embodiment, the heat-absorbing flame retardant may be or includes an inorganic hydroxide compound.

[0021] In an example embodiment, the fibrous polymer may include at least one of polytetrafluoroethylene, cellulose nanofibers, and polycaprolactam.

[0022] In the example embodiment, the mass ratio of the heat-absorbing flame retardant to the fibrous polymer can be in the range of about 1.5 to about 49.

[0023] In the example embodiment, the fibrillation rate of the fibrillated polymer can be in the range of about 1% to about 40%.

[0024] In the example embodiment, the average diameter of the heat-absorbing flame retardant can be in the range of about 0.1 μm to about 50 μm. Attached Figure Description

[0025] The accompanying drawings illustrate exemplary embodiments of the present disclosure and, together with the following detailed description, serve to provide a further understanding of the technical principles of the present disclosure. However, the present disclosure is not to be construed as limited to the details shown in the drawings, in which: Figure 1 This is a schematic perspective view illustrating an example of a battery module according to an exemplary embodiment of the present disclosure; Figure 2 It is shown Figure 1 A schematic perspective view of examples of battery cells and spacers in a battery module; Figure 3 It shows along Figure 2 A schematic cross-sectional view of an example of a section cut by line III-III'; Figure 4 Is included Figure 1 Scanning electron microscope (SEM) images of the fibrous polymer and heat-absorbing flame retardant in the spacer; and Figure 5 This is a flowchart illustrating a method for manufacturing a spacer according to an example of this disclosure. Detailed Implementation

[0026] In the following description, exemplary embodiments of the present disclosure are described with reference to the accompanying drawings. Before description, it should be understood that the terminology used in the specification and appended claims should not be construed as limited to its general or dictionary meaning, but rather interpreted based on the principle of allowing the inventor to appropriately define terms for best description, and on the meaning and concepts corresponding to the technical aspects of the present disclosure. Therefore, the exemplary embodiments disclosed in this specification and the constructions shown in the drawings are merely exemplary embodiments of the present disclosure and do not represent all the technical ideas of the present disclosure. It should be understood that various equivalents and modifications may exist to replace these exemplary embodiments at the time of filing this application.

[0027] Furthermore, the terms “including and encompassing” and / or variations thereof used in this specification should be interpreted as indicating the presence of the described shapes, quantities, steps, operations, components, elements and / or groups thereof, without excluding the presence or addition of other shapes, quantities, operations, components, elements and / or groups thereof.

[0028] Furthermore, for better understanding of this disclosure, the drawings are not shown to scale, and the dimensions of some elements may be exaggerated. Additionally, the same reference numerals may be assigned to the same components in different embodiments.

[0029] It is understood that although the terms “first,” “second,” etc., are used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another, and unless otherwise specifically described, a first element may also be a second element.

[0030] Throughout this specification, unless otherwise specifically stated, each element may be singular or plural.

[0031] When it is mentioned that any element is positioned on the “upper (or lower)” of a component or above (or below) a component, this can mean not only that the arbitrary element is positioned to contact the upper (or lower) surface of the component, but also that another element can be positioned between the component and the arbitrary element positioned above (or below) the component.

[0032] Furthermore, when referring to an element being “connected” or “joined” to another element, this can mean that the elements are directly connected or joined to each other. However, it should be understood that the other element may be “placed” between these elements, or that these elements may be “connected” or “joined” to each other via another element. In addition, the term “electrical connection” can mean not only “direct connection” but also “connection via other interposed elements.”

[0033] When the terms “about” or “substantially” are used in conjunction with numerical values ​​in this specification, it is intended that the relevant numerical value include a tolerance of ±10% around the stated value. When a range is specified, the range includes all values ​​within that range, such as increments of 0.1%.

[0034] Figure 1 This is a schematic perspective view showing an example of a battery module 100 according to an exemplary embodiment of the present disclosure. Figure 2 It is shown Figure 1 A schematic perspective view of an example of a battery cell 10 and a spacer 200 in a battery module 100. Figure 3 It shows along Figure 2 A schematic cross-sectional view of an example of a section cut by line III-III'. Figure 4 Is included Figure 1 Scanning electron microscope (SEM) images of the fibrous polymer and heat-absorbing flame retardant in the spacer.

[0035] First, refer to Figures 1 to 3According to an example embodiment of the present disclosure, a battery module 100 may include a plurality of battery cells 10 arranged in one direction, a spacer 200 located between the battery cells 10, and a pair of end plates 61, 62 located at opposite ends of the plurality of battery cells 10.

[0036] Multiple battery cells 10 can be arranged in one direction such that the wide surfaces of the battery cells 10 face each other, and the multiple battery cells 10 arranged can be fixed by housings 61, 62, 63, and 64.

[0037] The housings 61, 62, 63, and 64 may include a pair of end plates 61 and 62 facing the wide surface of the battery cell 10, and a side plate 63 and a bottom plate 64 connecting the pair of end plates 61 and 62 together.

[0038] A pair of end plates 61, 62 can be located at opposite ends of a plurality of battery cells 10 to compress the plurality of battery cells 10. Therefore, the internal components of the battery module 100, including the battery cells 10, can be substantially protected from external impacts, and physical deformations such as expansion phenomena in the battery module 100 can be reduced or prevented.

[0039] Side plate 63 can support the side surface of battery cell 10, and bottom plate 64 can support the bottom surface of battery cell 10. In addition, a pair of end plates 61, 62, side plate 63 and bottom plate 64 can be connected to each other by components such as bolts 65.

[0040] Each of the plurality of battery cells 10 may be equipped with terminal portions 11, 12 and an exhaust port 13. The terminal portions 11, 12 are electrically connected to the connecting tab 20, and the exhaust port 13 is a channel for venting any gases that may be generated internally. The terminal portions 11, 12 of the battery cell 10 may be first terminals 11 and second terminals 12 with different polarities. As an example, when the first terminal 11 is a positive electrode terminal, the second terminal 12 may be a negative electrode terminal, and conversely, when the first terminal 11 is a negative electrode terminal, the second terminal 12 may be a positive electrode terminal. That is, the first terminal 11 and the second terminal 12 are configured to have different polarities and are not limited to a specific polarity.

[0041] The terminal portions 11 and 12 of adjacent battery cells 10a and 10b can be connected in series or in parallel via the connecting tabs 20 described below. (See reference...) Figure 1 An example of a series connection has been described, but this disclosure is not limited to this structure, and various connection structures can be adopted as needed. Furthermore, the number and configuration of the battery cells 10 are not limited to this. Figure 1 The structure shown can be modified as desired.

[0042] For example, the battery module 100 includes a connecting piece 20 and a protection circuit module 30. The connecting piece 20 connects one battery cell 10a to another battery cell 10b adjacent to it, and the protection circuit module 30 has an end connected to the connecting piece 20.

[0043] The protection circuit module 30 may be or may include a battery management system (BMS). The connecting tab 20 includes a body portion that contacts the terminal portions 11 and 12 between adjacent battery cells 10a and 10b, and an extension portion that extends from the body portion and connects to the protection circuit module 30.

[0044] The protection circuit module 30 can be configured with electronic components and protection circuits, and can be electrically connected to the connecting terminal block 20.

[0045] The protection circuit module 30 may include a first protection circuit module 30a and a second protection circuit module 30b, which extend at different locations along the direction in which the plurality of battery cells 10 are arranged. In this case, the first protection circuit module 30a and the second protection circuit module 30b may be spaced apart from each other by a given distance and may be positioned parallel to each other, and each of the first protection circuit module 30a and the second protection circuit module 30b may be electrically connected to an adjacent connecting piece 20.

[0046] For example, the first protection circuit module 30a can be configured to extend on one upper side of the plurality of battery cells 10 along the direction along which the plurality of battery cells 10 are arranged, and the second protection circuit module 30b can be configured to extend on another upper side of the plurality of battery cells 10 along the direction along which the plurality of battery cells 10 are arranged. The second protection circuit module 30b can be spaced apart from the first protection circuit module 30a by a given interval when the exhaust port 13 is placed between the second protection circuit module 30b and the first protection circuit module 30a, and can be configured to be parallel to the first protection circuit module 30a.

[0047] Therefore, the two protection circuit modules 30a and 30b are configured to be parallel to each other and spaced apart from each other in the direction along which the plurality of battery cells 10 are arranged, thereby reducing or minimizing the unnecessary area of ​​the printed circuit board (PCB) constituting the protection circuit module 30.

[0048] The first protection circuit module 30a and the second protection circuit module 30b can be connected to each other via a conductive connecting member 50. For example, one side of the connecting member 50 can be connected to the first protection circuit module 30a, and the other side of the connecting member 50 can be connected to the second protection circuit module 30b, so that an electrical connection can be established between the two protection circuit modules 30a and 30b.

[0049] The connection can be performed by any of the following methods: brazing, resistance welding, laser welding, and projection welding.

[0050] The connecting member 50 may be, for example, an electrical wire. Furthermore, the connecting member 50 may be made of or include elastic or flexible materials. Through the connecting member 50, it is possible to check and manage whether the voltage, temperature, and current of multiple battery cells 10 are normal or within the expected range.

[0051] For example, information such as voltage, current and temperature received by the first protection circuit module 30a from its adjacent connecting piece 20 and information such as voltage, current and temperature received by the second protection circuit module 30b from its adjacent connecting piece 20 can be managed as a whole by the protection circuit module 30 through the connecting member 50.

[0052] For example, when the battery cell 10 expands, the impact is essentially absorbed due to the elasticity or flexibility of the connecting member 50, thereby reducing or preventing damage to the first protection circuit module 30a and the second protection circuit module 30b.

[0053] For example, the shape and structure of the connecting member 50 are not limited to Figure 1 The shape shown.

[0054] In the example, because the protection circuit module 30 is configured as a first protection circuit module 30a and a second protection circuit module 30b, the area of ​​the PCB constituting the protection circuit module 30 can be reduced or minimized, thereby ensuring sufficient space inside the battery module 100. Therefore, the fastening operation of connecting the connecting tabs 20 and the protection circuit module 30 can be facilitated, and repairs can be made easier when an abnormality is detected in the battery module 100, thus improving operational efficiency.

[0055] For example, such as Figure 3 As shown, the battery cell 10 may include a housing 15 for the battery, an electrode assembly 210 housed in the housing 15 for the battery, and an electrolyte. The electrode assembly 210 and the electrolyte react electrochemically with each other to generate energy.

[0056] The battery cell 10 may include a housing 15 and at least one electrode assembly 210, wherein a separator 213, which serves as an insulator, is placed between a positive electrode 211 and a negative electrode 212 and then wound up, and the electrode assembly 210 is housed in the housing 15.

[0057] An example of a prismatic lithium-ion battery cell 10 according to an exemplary embodiment has been described. However, this disclosure is not limited thereto, and it can be applied to various types of battery cells, such as lithium polymer battery cells or cylindrical battery cells.

[0058] The positive electrode 211 and the negative electrode 212 may include coated portions and uncoated portions 211a and 212a. The coated portions are areas on which active material is applied to a current collector made of or including a thin metal foil, and the uncoated portions 211a and 212a are areas on which active material is not coated.

[0059] The positive electrode 211 and the negative electrode 212 can be wound up after the diaphragm 213, which serves as an insulator, is placed between the positive electrode 211 and the negative electrode 212. However, this disclosure is not limited thereto, and the electrode assembly 210 may have a structure in which positive electrodes 110 and negative electrodes 120, each comprising a plurality of sheets, are alternately stacked with the diaphragm 213 placed between them.

[0060] The housing 15 can form the overall appearance of the battery cell 10 and can be made of or include a conductive metal (such as at least one of aluminum, aluminum alloy and nickel-plated steel). In addition, the housing 15 can provide space to accommodate the electrode assembly 210.

[0061] The battery cell 10 may include a cover 17 that covers the opening of the housing 15, and the housing 15 and the cover 17 may be made of or comprise conductive material. Here, the first terminal 11 and the second terminal 12, which are electrically connected to the positive electrode 211 and the negative electrode 212, may be configured to pass through the cover 17 and protrude to the outside.

[0062] Furthermore, the outer peripheral surfaces of the upper columns protruding outward from the cover plate 17 of the first terminal 11 and the second terminal 12 can be threadedly connected to and fixed to the cover plate 17 by a fixing device (such as a nut).

[0063] However, the examples disclosed herein are not limited thereto, and the first terminal 11 and the second terminal 12 may have a riveted structure for being riveted together, or may be welded and joined to the cover plate 17.

[0064] Furthermore, the cover plate 17 may be made of or comprise a thin plate and may be coupled to an opening in the housing 15. An electrolyte injection port 14 may be constructed in the cover plate 17, and an exhaust port 13 may be installed therein. A sealing plug may be installed on the electrolyte injection port 14, and a notch may be formed in the exhaust port 13.

[0065] The first terminal 11 and the second terminal 12 can be electrically connected to the current collector, which includes a first current collector 240 and a second current collector 250 (hereinafter referred to as the positive electrode current collector and the negative electrode current collector) that are welded to the uncoated portion 211a of the positive electrode and the uncoated portion 212a of the negative electrode.

[0066] For example, the first terminal 11 and the second terminal 12 can be soldered to the positive electrode current collector 240 and the negative electrode current collector 250. However, this disclosure is not limited thereto, and the first terminal 11 and the second terminal 12, as well as the positive electrode current collector 240 and the negative electrode current collector 250, can be integrally bonded to each other.

[0067] Furthermore, an insulating member may be installed between the electrode assembly 210 and the cover plate 17. Here, the insulating member may include a first lower insulating member 260 and a second lower insulating member 270, and each of the first lower insulating member 260 and the second lower insulating member 270 may be installed between the electrode assembly 210 and the cover plate 17.

[0068] Furthermore, according to this example embodiment, one end of a separator member that can be mounted to face one side surface of the electrode assembly 210 can be mounted between the insulating member and each of the first terminal 11 and the second terminal 12.

[0069] Here, the separating member may include a first separating member 280 and a second separating member 290.

[0070] Therefore, one end of the first separating member 280 and the second separating member 290 that can face one side surface of the electrode assembly 210 can be installed between the first lower insulating member 260 and the second lower insulating member 270 and the first terminal 11 and the second terminal 12.

[0071] As a result, the first terminal 11 and the second terminal 12, which are connected to the positive electrode current collector 240 and the negative electrode current collector 250, can be connected to the ends of the first lower insulating member 260 and the second lower insulating member 270, as well as the ends of the first separating member 280 and the second separating member 290.

[0072] For example, refer to Figure 1 and Figure 2 Spacers 200 can be disposed between battery cells 10. This prevents adjacent battery cells 10a, 10b from directly contacting each other, thereby reducing or preventing chain explosions of the arranged battery cells 10 due to high-temperature heat transfer. Spacers 200 can be configured to have dimensions corresponding to the wide surface of the battery cell 10.

[0073] The spacer 200 may include a polymer matrix and a heat-absorbing flame retardant dispersed in the polymer matrix, thereby substantially absorbing the heat released in the event of a fire to reduce or prevent temperature rise.

[0074] The polymer matrix may include fibrous polymers. Because conventional materials used as spacers require additional materials such as adhesives, there are limitations on the addition of heat-absorbing flame retardants in amounts ranging from about 40 wt% to more. However, in the composite materials according to this disclosure, because an adhesive, fibrous material is used, the content of the heat-absorbing flame retardant can be increased to about 60 wt% or more.

[0075] Such fibrous polymers may include at least one of polytetrafluoroethylene, cellulose nanofibers and polycaprolactam, but one or more embodiments are not limited thereto.

[0076] The heat-absorbing flame retardant can be included in a content ranging from about 60 wt% to about 98 wt% relative to the total weight of the spacer 200. Therefore, even when the spacer 200 is formed thin, the heat-absorbing and heat-resistant properties of the spacer 200 can be achieved, and the filling density of the battery module 100 can be increased. Furthermore, the mass ratio (i.e., weight ratio) of the heat-absorbing flame retardant to the fibrous polymer can be in the range of about 1.5 to about 49.

[0077] When the content of the heat-absorbing flame retardant is less than about 60 wt% of the total weight of spacer 200, the flame retardant and heat-absorbing effects may be insufficient, and therefore the filler density may decrease due to the increased thickness of the composite material. Conversely, when the heat-absorbing flame retardant is included in a content of more than about 98 wt% of the total weight of spacer 200, the polymer material may not be able to act as a matrix, which may lead to difficulties in manufacturing spacer 200.

[0078] For example, when the mass ratio of the endothermic flame retardant to the fibrous polymer is less than about 1.5, it may not exhibit flame retardant effects, and when the mass ratio exceeds about 49, there may be challenges in achieving composite materials.

[0079] Such endothermic flame retardants may be or include hydroxide inorganic compounds or oxide inorganic compounds. Endothermic flame retardants may include at least one of magnesium hydroxide, aluminum hydroxide, antimony trioxide, and antimony pentoxide, but one or more example embodiments are not limited thereto.

[0080] Figure 4 Is included Figure 1 Scanning electron microscope (SEM) images of the fibrous polymer and heat-absorbing flame retardant in the spacer. Figure 4 The prepared fibrous polytetrafluoroethylene (B) and magnesium hydroxide (A) according to the example embodiment are shown.

[0081] This disclosure describes a spacer comprising a fibrous polymer, thus eliminating the need for additional materials other than the polymer material and the flame retardant, and achieving the desired or improved flame retardant effect by using an adhesive, fibrous material comprising an endothermic flame retardant in a content of about 60 wt% or more.

[0082] For example, when fibrillation within the polymer matrix is ​​insufficient, the binding force of the flame retardant in the matrix may be low, which can make increasing the content of endothermic flame retardants challenging. Conversely, when the polymer matrix is ​​over-fibrillated, there may be challenges in the stratification of the endothermic flame retardant rather than its bonding with the fibrillated polymer. Therefore, the fibrillation rate of the fibrillated polymer in the matrix can range from about 1% to about 40%.

[0083] In the example, the endothermic flame retardant can have an average diameter of about 0.1 μm to about 50 μm, and can be included in an amount of about 60 wt% to about 98 wt% relative to the total weight of the spacer 200. As the diameter of the endothermic flame retardant decreases, the surface area can increase, and the flame retardancy can be improved. However, when the diameter is less than about 0.1 μm, there may be challenges in terms of adhesion. Conversely, when the diameter exceeds about 50 μm, there may be challenges in terms of reduced flame retardancy.

[0084] Figure 5 This is a flowchart illustrating a method for manufacturing a spacer according to an example of this disclosure.

[0085] like Figure 5 As shown, the method for manufacturing a spacer according to this disclosure includes: operation S10, mixing polymer powder and a heat-absorbing flame retardant; operation S20, pressing the mixture of polymer powder and heat-absorbing flame retardant; and operation S30, molding the pressed mixture of polymer powder and heat-absorbing flame retardant. The content of polymer powder and heat-absorbing flame retardant can be determined taking into account processing performance and flame retardant performance.

[0086] The mixing process can be performed by applying shear force to the polymer material to achieve fiberization and substantially uniformly mix the material, and can be performed by using, for example, a ball mill, a high-speed mixer or a closed mixer, but one or more example embodiments are not limited thereto.

[0087] Furthermore, the mixing time and mixing temperature can vary depending on the method. For example, when using polytetrafluoroethylene, the mixing process can be performed at a temperature of about 30°C or higher for at least about 1 minute, but one or more example embodiments are not limited to this.

[0088] A pressing process can be performed to incorporate an endothermic flame retardant into a polymer material that exists in the form of a separate powder, and the pressing process can be performed manually or using automated equipment.

[0089] If necessary, further operations can be performed to improve the binding force of the prepared mixture. For example, the mechanical properties can be improved by repeating the rolling process, and the binding force and shape freedom of the mixture can be changed by optimizing the process.

[0090] This disclosure is described in more detail by way of the following examples.

[0091] Example 1: A composite material was prepared by mixing polymer powder and an endothermic flame retardant, followed by pressing. The composite material was also prepared by adding cellulose nanofibers and magnesium hydroxide as polymer and flame retardant in a 5:95 weight ratio.

[0092] Comparison Example 1: Cellulose nanofibers without added magnesium hydroxide were used as the composite material in Comparative Example 1.

[0093] Compare with Example 2: The composite material was prepared in the same manner as in Example 1, except that cellulose nanofibers and magnesium hydroxide were added in a weight ratio of 90:10.

[0094] Compare with Example 3: The composite material was prepared in the same manner as in Example 1, except that cellulose nanofibers and magnesium hydroxide were added in a weight ratio of 75:25.

[0095] Compare with Example 4: The composite material was prepared in the same manner as in Example 1, except that cellulose nanofibers and magnesium hydroxide were added in a 50:50 weight ratio.

[0096] Table 1 below shows the addition ratio of cellulose nanofibers and magnesium hydroxide in Example 1 of this disclosure and Comparative Examples 1 to 4.

[0097] Table 1:

[0098] Experimental Example 1: Flame Retardancy Evaluation Flame retardancy was evaluated on the composite materials prepared in Example 1 and Comparative Examples 1 to 4. Flame retardancy was evaluated based on the flame retardancy rating, limiting oxygen index, and heat release value according to the UL94 method.

[0099] Table 2 below shows the results of the flame retardancy evaluation according to Experimental Example 1 of this disclosure.

[0100] Table 2:

[0101] Referring to Table 2 above, compared with pure cellulose nanofibers (Comparative Example 1), the flame retardancy rating was evaluated as better with increasing magnesium hydroxide content. As a result of the flame retardancy evaluation, Example 1, with a flame retardancy rating of V-0, a limiting oxygen index (LOI) of 95% or greater, and a total heat release (THR) of 3 MJ / m², exhibited the desired or improved flame retardant effect.

[0102] According to an example embodiment of this disclosure, the spacers located between the battery cells can absorb the heat released in the event of a battery fire, thereby reducing or preventing a chain reaction of temperature rise and fire.

[0103] However, the effects that can be achieved through this disclosure are not limited to those described above, and those skilled in the art will clearly understand, based on the above disclosure, other technical effects not described herein.

[0104] Although this disclosure has been described with limited exemplary embodiments and accompanying drawings, it is not limited thereto. Rather, it will be understood by those skilled in the art that various modifications and changes can be made to these exemplary embodiments without departing from the principles and spirit of this disclosure, the scope of which is defined by the claims and their equivalents.

Claims

1. A spacer, the spacer comprising: Polymer matrix; as well as An endothermic flame retardant is dispersed in the polymer matrix. The polymer matrix comprises a fibrous polymer, and The heat-absorbing flame retardant is included in a content ranging from 60 wt% to 98 wt% relative to the total weight of the spacer.

2. The spacer according to claim 1, wherein, The heat-absorbing flame retardant includes an inorganic compound of hydroxide.

3. The spacer according to claim 1, wherein, The fibrous polymer includes at least one of polytetrafluoroethylene, cellulose nanofibers, and polycaprolactam.

4. The spacer according to claim 1, wherein, The mass ratio of the heat-absorbing flame retardant to the fibrous polymer is in the range of 1.5 to 49.

5. The spacer according to claim 1, wherein, The fibrillation rate of the fibrillated polymer is in the range of 1% to 40%.

6. The spacer according to claim 1, wherein, The average diameter of the heat-absorbing flame retardant is in the range of 0.1 μm to 50 μm.

7. The spacer according to claim 1, wherein, The heat-absorbing flame retardant includes at least one of magnesium hydroxide, aluminum hydroxide, antimony trioxide, and antimony pentoxide.

8. A battery module, the battery module comprising: Multiple battery cells; as well as Spacers are disposed between the plurality of battery cells. Each of the spacers comprises a polymer matrix and a heat-absorbing flame retardant dispersed in the polymer matrix. The polymer matrix comprises a fibrous polymer, and The heat-absorbing flame retardant is included in a content ranging from 60 wt% to 98 wt% relative to the total weight of the spacer.

9. The battery module according to claim 8, wherein, The heat-absorbing flame retardant includes an inorganic compound of hydroxide.

10. The battery module according to claim 8, wherein, The fibrous polymer includes at least one of polytetrafluoroethylene, cellulose nanofibers, and polycaprolactam.

11. The battery module according to claim 8, wherein, The mass ratio of the heat-absorbing flame retardant to the fibrous polymer is in the range of 1.5 to 49.

12. The battery module according to claim 8, wherein, The fibrillation rate of the fibrillated polymer is in the range of 1% to 40%.

13. The battery module according to claim 8, wherein, The average diameter of the heat-absorbing flame retardant is in the range of 0.1 μm to 50 μm.

14. The battery module according to claim 8, wherein, Each of the plurality of battery cells includes an electrode assembly and a conductive metal housing, the electrode assembly including a positive electrode, a negative electrode and a separator between the positive electrode and the negative electrode, the electrode assembly being housed within the conductive metal housing.

15. A method for manufacturing a spacer, the method comprising the following steps: A mixture is formed by mixing an endothermic flame retardant and polymer powder; The mixture of the heat-absorbing flame retardant and the polymer powder is pressed; as well as Spacers are formed by molding the mixture of the heat-absorbing flame retardant and the polymer powder. The spacer comprises a polymer matrix and a heat-absorbing flame retardant dispersed in the polymer matrix. The polymer matrix comprises a fibrous polymer, and The heat-absorbing flame retardant is included in a content ranging from 60 wt% to 98 wt% relative to the total weight of the spacer.

16. The method according to claim 15, wherein, The heat-absorbing flame retardant includes an inorganic compound of hydroxide.

17. The method according to claim 15, wherein, The fibrous polymer includes at least one of polytetrafluoroethylene, cellulose nanofibers, and polycaprolactam.

18. The method according to claim 15, wherein, The mass ratio of the heat-absorbing flame retardant to the fibrous polymer is in the range of 1.5 to 49.

19. The method according to claim 15, wherein, The fibrillation rate of the fibrillated polymer is in the range of 1% to 40%.

20. The method of claim 15, wherein, The average diameter of the heat-absorbing flame retardant is in the range of 0.1 μm to 50 μm.

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