CN118825577A - Battery insulation sheet, manufacturing method thereof and battery module including the same - Google Patents

Abstract

The invention provides a battery insulating sheet, a manufacturing method thereof and a battery module comprising the same. The battery insulating sheet includes an aerogel layer. The aerogel layer comprises: a fibrillated polymer matrix comprising a dry binder; and aerogel particles distributed in the fibrillated polymer matrix.

Description

Battery insulation sheet, manufacturing method thereof and battery module including the same

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0052566 filed on April 21, 2023, and No. 10-2023-0106093 filed on August 14, 2023, respectively, in the Korean Intellectual Property Office, and the entire disclosure of each of the above patent applications is incorporated herein by reference.

Technical Field

Aspects of embodiments of the present disclosure relate to a battery insulating sheet, a method of manufacturing the same, and a battery module including the same.

Background Art

Secondary batteries are energy storage systems that convert electrical energy into chemical energy, store chemical energy and provide high energy density. Compared with primary batteries that are not designed to be rechargeable, secondary batteries are designed to be rechargeable and are widely used in IT devices, such as smart phones, mobile phones, laptop computers and tablet computers. Recently, people are increasingly interested in electric vehicles as a way to reduce or prevent environmental pollution, and high-capacity secondary batteries are being applied to electric vehicles. Secondary batteries usually show characteristics such as high density, high output and good stability.

If a battery module (such as a lithium secondary battery) includes a plurality of high-capacity battery cells, one battery cell may overheat for various reasons and may thermally run away, which may adversely affect other battery cells adjacent thereto. Therefore, it is desirable that adjacent battery cells be thermally isolated from each other.

Conventionally, in some cases, a plate or an insulating resin sheet is disposed between battery cells to isolate and insulate adjacent battery cells from each other.

The information disclosed in this section is provided for enhancement of understanding of the background of the disclosure and therefore, it may contain information that is not related (or prior) art.

Summary of the invention

Embodiments of the present disclosure provide a battery insulating sheet having desirable thermal insulation, heat resistance, low dust characteristics, and flexibility, a manufacturing method thereof, and a battery module including the same.

According to an embodiment of the present disclosure, a battery insulation device includes an aerogel layer including: a fibrillated polymer matrix including a dry binder; and aerogel particles distributed in the fibrillated polymer matrix.

The dry binder may include a fluorinated binder, wherein the fluorinated binder is at least one selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride-hexapropylene copolymer, and polyvinylidene fluoride.

The fibrillated polymer matrix may account for 10 wt % to 90 wt % of the total amount of the aerogel layer, and the aerogel particles may account for 10 wt % to 90 wt % of the total amount of the aerogel layer.

The aerogel particles may have a BET specific surface area ranging from 500 m ² /g to 1,000 ^{m 2} /g.

The aerogel particles may have an average particle size (D50) ranging from 5 μm to 100 μm.

Aerogel particles may be dispersed within the interior of the fibrillated polymer matrix.

The aerogel layer may satisfy the following formula 1:

[Formula 1]

0.1≤W _FB /T _PM ≤18

wherein W _FB is the content of dry binder in the total amount of the aerogel layer (in wt%), and T _PM is the average particle size of the aerogel particles (in μm).

The battery insulating sheet may further include a substrate on an upper surface, a lower surface, or both of the upper and lower surfaces of the aerogel layer.

The battery insulating sheet may have a structure in which a first substrate, an aerogel layer, and a second substrate are sequentially laminated.

According to an embodiment of the present disclosure, a method for manufacturing a battery insulating sheet includes: manufacturing a raw material mixture including a powdered dry binder and powdered aerogel particles; and extruding the raw material mixture by using an extruder to manufacture an aerogel layer, wherein the aerogel layer includes a fibrillated polymer matrix, the fibrillated polymer matrix includes the dry binder, and the aerogel particles are distributed in the fibrillated polymer matrix.

The production of the raw material mixture may include a primary dry mixing step or a primary dry mixing step and a secondary dry mixing step.

The production of the raw material mixture may include a primary dry mixing step and a secondary dry mixing step, and a stirring speed in the secondary dry mixing step may be at least twice the stirring speed in the primary dry mixing step.

In the primary dry mixing step, the temperature may range from 20°C to 65°C, the stirring speed may range from 2000 rpm or less, and the stirring time may range from 5 min to 15 min. In the secondary dry mixing step, the temperature may range from 20°C to 65°C, the stirring speed may range from 4000 rpm to 10,000 rpm, and the stirring time may range from 10 min to 60 min.

The production of the aerogel layer may include introducing a raw material mixture into an extruder and extruding the raw material mixture into a sheet form.

The production of the aerogel layer may be performed at a temperature ranging from 25° C. to 150° C. and a pressure ranging from 1 MPa to 100 MPa.

The method of manufacturing a battery insulating sheet may further include laminating a substrate on an upper surface, a lower surface, or both the upper surface and the lower surface of the aerogel layer.

The first substrate and the second substrate may be laminated on the upper and lower surfaces of the aerogel layer, respectively.

According to an embodiment of the present disclosure, a battery module includes: a plurality of battery cells; and a battery insulating sheet as described above between the plurality of battery cells. The upper surface and the lower surface of the battery insulating sheet respectively face adjacent battery cells among the plurality of battery cells.

BRIEF DESCRIPTION OF THE DRAWINGS

The attached drawings incorporated into this specification illustrate embodiments of the present disclosure, and are provided in conjunction with the following detailed description to further illustrate aspects and features of the present disclosure. The present disclosure should not be construed as limited to what is shown in these drawings. In the drawings:

FIG1 is a schematic diagram showing the structure of a battery insulation sheet according to an embodiment;

FIG2 is a schematic diagram showing the structure of a battery insulation sheet according to another embodiment;

FIG3 is a schematic diagram showing the structure of a battery insulation sheet according to another embodiment;

FIG. 4 is a schematic diagram illustrating a battery insulating sheet between a plurality of battery cells according to an embodiment.

DETAILED DESCRIPTION

Hereinafter, the embodiments of the present disclosure will be described in detail so that those skilled in the art can easily implement the embodiments. However, the present disclosure and the described embodiments may be implemented in many different forms and are not limited to the embodiments described herein.

It will be understood that when an element or layer is referred to as being "on," "connected to," or "coupled to" another element or layer, it may be directly on, connected to, or coupled to the other element or layer, or there may be one or more intervening elements or layers. When an element or layer is referred to as being "directly on," "directly connected to," or "directly coupled to" another element or layer, there may be no intervening elements or layers. For example, when a first element is described as being "coupled to" or "connected to" a second element, the first element may be directly coupled to or connected to the second element, or the first element may be indirectly coupled to or connected to the second element via one or more intervening elements.

In the accompanying drawings, for clarity of explanation, the dimensions of various elements, layers, etc. can be enlarged. The same reference numerals mark the same elements. As used in this article, the term "and/or" includes any and all combinations of one or more related enumerated items. Further, when describing the embodiments of the present disclosure, the use of "may" relates to "one or more embodiments of the present disclosure". When after the list of elements, expressions such as "at least one of" and "any of" modify the entire list of elements and do not modify the individual elements of the list. For example, the expression "at least one of a, b, and c" indicates only a, only b, only c, both a and b, both a and c, both b and c, all a, b, and c, or variations thereof. As used in this article, the terms "use", "using", and "used" can be considered to be synonymous with the terms "utilize", "utilizing", and "utilized", respectively. As used in this article, the terms "substantially", "about", and similar terms are used as approximate terms, and are not used as terms of degree, and are intended to illustrate the inherent changes in measured or calculated values that will be recognized by those of ordinary skill in the art.

It will be understood that although the terms first, second, third, etc. may be used in this article to describe various elements, components, regions, layers and/or parts, these elements, components, regions, layers and/or parts should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the example embodiments, the first element, component, region, layer or part discussed below may be referred to as the second element, component, region, layer or part.

For ease of description, spatially relative terms, such as "below," "below," "below," "above," "on," etc., may be used herein to describe the relationship of one element or feature to another element or feature illustrated in the drawings. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the drawings. For example, if the device in the drawings is turned over, then the elements described as "below" or "below" other elements or features are then oriented "above" or "on" the other elements or features. Thus, the term "below" may encompass both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

The terms used in this article are intended to describe the embodiments of the present disclosure and are not intended to limit the present disclosure. As used in this article, the singular forms "a" and "an" are also intended to include the plural forms, unless the context clearly indicates otherwise. It will be further understood that when used in this specification, the terms "includes", "including", "comprises" and/or "comprising" indicate the presence of narrated features, integers, steps, operations, elements and/or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.

Insulation is a material that prevents or reduces the flow of heat from a higher temperature area to a lower temperature area and is used not only in refrigerators, cold storage and buildings, but also in various other industries, including aircraft, electronic equipment and the automotive industry.

Insulating materials provide the desired thermal insulation properties through low thermal conductivity and mechanical strength to maintain the thermal insulation properties over time.

Aerogel is a high-grade transparent or translucent material with a nanoporous structure, showing very low density and low thermal conductivity. Therefore, aerogel has attracted attention as an insulating material and is considered to be a highly efficient super-insulating material that can be used in various industrial applications.

Some aspects of aerogels are that the thermal conductivity of aerogels is lower than conventional organic insulating materials, such as closed-cell foams, e.g. (a registered trademark owned by DDP SPECIALTY ELECTRONIC MATERIALS US, INC.), and aerogel avoids weaknesses of organic insulating materials, such as fire vulnerability and generation of harmful gases during fire.

A battery insulation sheet according to an embodiment may include an aerogel layer including a fibrillated polymer matrix and aerogel particles distributed in the fibrillated polymer matrix. In some embodiments, the fibrillated polymer matrix may include a dry binder.

The battery insulating sheet having the above structure may include a relatively high content of a dry binder that exhibits heat resistance to improve heat resistance and thermal insulation. The dry binder may be present in a fibrillated polymer matrix structure, and aerogel particles may be dispersed in the fibrillated polymer matrix, so that the battery insulating sheet may have desired flexibility, and separation of aerogel particles (also called dust) may be alleviated or prevented, so that the battery insulating sheet may have low dust characteristics.

The dry binder may have a desired heat resistance, but may be relatively difficult to disperse in water. However, the battery insulating sheet according to the embodiment may include a relatively high content of the dry binder without affecting the dispersibility of the dry binder through the drying process, so that the dry binder can be easily included in the battery insulating sheet, thereby providing improved heat resistance, the desired heat resistance can be achieved by a relatively thin thickness of the battery insulating sheet, and the separation of aerogel particles can be reduced.

In an embodiment, the fibrillated polymer matrix may not include (or may omit any) aqueous binder. The aqueous binder may refer to a common water-soluble binder and may include, for example, an inorganic binder, an aqueous polymer, an anionic water-soluble polymer, a cationic water-soluble polymer and/or a water-dispersible polymer.

The fibrillated polymer matrix may be manufactured by a dry process and may not include an aqueous binder. Since an aqueous binder is not included, an aerogel layer having an aerogel dispersed structure in the fibrillated polymer matrix may be formed by extrusion in a dry process (eg, a dry extrusion process).

The inorganic binder may include a soluble silicate and may be a common waterborne polymer such as sodium silicate, potassium silicate or lithium silicate.

The water-based polymer may refer to a common water-based polymer such as polyvinyl alcohol, polyethylene oxide, polyacrylamide or polyvinyl pyrrolidone.

The anionic water-soluble polymer may refer to a common anionic water-soluble polymer such as a polymer having a functional group of carboxylic acid, sulfonic acid, sulfate ester and/or phosphate ester, or a polymer having a functional group of a salt thereof.

The cationic water-soluble polymer may refer to at least one selected from the group consisting of polymers having functional groups of amines, ammoniums, phosphoniums, sulfoniums, and salts thereof. For example, the cationic water-soluble polymer may be a polymer having an amine group, and the cationic water-soluble polymer may be a common cationic water-soluble polymer, such as polyethyleneamine or polyamine.

The water-dispersible polymer may refer to a common water-dispersible polymer such as water-dispersible polyurethane or water-dispersible polyester.

The dry binder may be, for example, a fibrillating binder.The dry binder may be a binder capable of fibrillating or a binder that fibrillates to form a matrix.

The dry binder may be a binder that is not impregnated in a solvent, not dissolved in a solvent, and/or not dispersed in a solvent. The dry binder may be a fibrillated binder that may serve as a matrix configured to support and bind aerogels (e.g., aerogel particles). The dry binder may have an aspect ratio of about 10 or greater, about 20 or greater, about 50 or greater, or about 100 or greater.

The dry binder may include at least one copolymer selected from the group consisting of polytetrafluoroethylene (PTFE), polyvinylidene fluoride-hexapropylene (PVDF-HFP) copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, cellulose, polyvinyl pyrrolidone, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR) and fluorinated rubber; however, embodiments of the present disclosure are not limited thereto.

For example, the dry binder may include a fluorinated binder. The fluorinated binder may include at least one selected from the group consisting of polytetrafluoroethylene (PTFE), polyvinylidene fluoride-hexapropylene (PVDF-HFP) copolymers and polyvinylidene fluoride (PVDF). Because the dry binder is included, the dry binder can be fibrillated by a drying process. In the drying process, the raw material mixture can be extruded using an extruder to manufacture an aerogel layer. If an aqueous binder is included, it can be difficult to fibrillate the binder.

In an embodiment, the aerogel particles may have a BET specific surface area ranging from about 500 m ² /g to about 1,000 m ² /g. For example, the aerogel particles may have a BET specific surface area ranging from about 500 m ² /g to about 950 m ² /g, about 550 m ² /g to about 950 m ² /g, or about 600 m ² /g to about 900 m ² /g. When aerogel particles having a BET specific surface area value within the above range are included, heat transfer and heat propagation between a plurality of battery cells may be effectively prevented, thereby improving thermal insulation of the battery insulation sheet.

The average particle size D50 of the aerogel particles may range from about 5 μm to about 100 μm, from about 10 μm to about 100 μm, or from about 50 μm to about 100 μm. When aerogel particles having a particle size within the above range are included, thermal insulation can be improved while substantially preventing agglomeration between aerogel particles and an increase in the thickness of a battery insulation sheet to further delay heat transfer between a plurality of battery cells.

The average particle size D50 can be measured, for example, by using a laser diffraction method or a scanning electron microscope (SEM). The average particle size D50 of the particles can be defined as the particle size at 50% of the particle size distribution (eg, the particle size corresponding to the cumulative 50% by volume of the particle size distribution).

The aerogel particles may be dispersed in the fibrillated polymer matrix.When the aerogel layer is formed by using the manufacturing method described below, the aerogel layer may be formed to have a structure in which the aerogel particles are uniformly or substantially uniformly dispersed in the fibrillated polymer matrix.

In an embodiment, the fibrillated polymer matrix may be included in an amount of about 10 wt % to about 90 wt % of the total amount of the aerogel layer, and the aerogel particles may be included in an amount of about 10 wt % to about 90 wt % of the total amount of the aerogel layer.

The fibrillated polymer matrix may be included in an amount of about 20 wt % to about 90 wt %, about 20 wt % to about 75 wt %, or about 20 wt % to about 65 wt % of the total amount of the aerogel layer, and the aerogel particles may be included in an amount of about 10 wt % to about 80 wt %, about 25 wt % to about 80 wt %, or about 35 wt % to about 80 wt % of the total amount of the aerogel layer. By varying the contents of the fibrillated polymer matrix and the aerogel particles in the aerogel layer within the above range, a battery insulating sheet having desired thermal insulation, heat resistance, flexibility, and low dust characteristics can be provided.

In an embodiment, the content of the dry binder may be adjusted according to the size of the aerogel particles. The aerogel layer may satisfy Formula 1 below.

Formula 1

0.1≤W _FB /T _PM ≤18

In the above Formula 1, W _FB indicates the content (wt %) of the dry binder relative to the total amount of the aerogel layer, and T _PM indicates the average particle size (μm) of aerogel particles.

The W _FB /T _PM value may range from about 0.1 to about 18, about 0.1 to about 10, about 0.1 to about 5, or about 0.2 to about 1.3. The W _FB /T _PM value may indicate a relationship between an average particle size of the aerogel particles and a content of a dry binder that may be included in the aerogel layer. For example, as the size of the aerogel particles increases, the dry binder may be more difficult to fill into the fibrillated polymer matrix, and as the size of the aerogel particles decreases, the specific surface area may increase, requiring an excess of dry binder, which may reduce the thermal insulation of the battery insulating sheet. Therefore, the aerogel particle size may affect the content of the dry binder that may be included. By adjusting the W _FB /T _PM value within the above range, therefore, it is possible to provide a thin thickness battery insulating sheet having desired thermal insulation, heat resistance, flexibility, and low dust characteristics.

The aerogel layer may have a structure in which aerogel particles are uniformly distributed in a fibrillated polymer matrix by using a manufacturing method, which will be described below. Even if the aerogel layer is formed to have a small thickness, the aerogel layer may have a desired thermal insulation because there are not many empty spaces therein. The aerogel layer may have a desired heat resistance because the aerogel layer may include a high content of a dry binder having heat resistance. Since the aerogel particles may be substantially uniformly distributed in the fibrillated polymer matrix, dust generated due to separation of the aerogel particles may be reduced or prevented. The internal voids of the aerogel layer may absorb vibrations and shocks, but the thickness of the battery insulating sheet may be increased.

The battery insulating sheet according to the embodiment can be used as an insulating sheet for various types of batteries because the aerogel layer can achieve desired flexibility through the fibrillated polymer matrix even if the aerogel layer does not have many internal voids, and in an environment where the battery is not stationary but running during operation, such as in electric vehicles, separation of aerogel particles can be prevented.

The thickness of the aerogel layer may range from about 1 mm to about 10 mm, about 1 mm to about 5 mm, or about 1 mm to about 3 mm. By forming an aerogel layer having a thickness within the above range on a substrate, a thin-thickness battery insulating sheet having desired thermal insulation, heat resistance, flexibility, and low dust characteristics may be manufactured.

In an embodiment, the battery insulating sheet may further include a substrate provided on an upper surface, a lower surface, or both of the upper and lower surfaces of the aerogel layer.

As an example, FIG. 1 is a schematic diagram showing the structure of a battery insulation sheet according to an embodiment.

1 , a battery insulation sheet 100 may include an aerogel layer 110. Upper and lower surfaces of the aerogel layer 110 may be disposed to face battery cells (eg, battery cells) adjacent thereto, respectively.

As another example, FIG. 2 is a schematic diagram showing the structure of a battery insulation sheet according to another embodiment.

2, the battery insulation sheet 100 includes a substrate 120 and an aerogel layer 110 formed on the substrate 120. An upper surface of the battery insulation sheet (eg, an upper surface of the aerogel layer 110) and a lower surface of the substrate 120 may be disposed to face battery cells adjacent thereto, respectively.

As yet another example, FIG. 3 is a schematic diagram illustrating a structure of a battery insulation sheet according to another embodiment.

3, the battery insulating sheet 100 may have a structure including a first substrate 130, an aerogel layer 110 formed on the first substrate 130, and a second substrate 140 on (e.g., formed on) the aerogel layer 110. The battery insulating sheet may have a structure in which the first substrate 130, the aerogel layer 110, and the second substrate 140 are sequentially laminated. The first substrate 130 and the second substrate 140 may be disposed to face the battery cells adjacent thereto, respectively. The first substrate 130 and the second substrate 140 may be made of the same material or different materials.

The substrate (e.g., the first substrate 130, the second substrate 140, or the substrate 120 as described above) may include, but is not limited to, resin, metal, inorganic materials other than metal, and/or a composite thereof. The form of the substrate may be, but is not limited to, a film, a diaphragm, a sheet, etc. The substrate may refer to the substrate 120 shown in FIG. 2 or the first substrate 130 and the second substrate 140 shown in FIG. 3.

The resin may include at least one selected from the group consisting of, for example, polyethylene, polypropylene, polystyrene, polyethylene terephthalate, and polyamide.

The metal may include at least one selected from the group consisting of, for example, copper, nickel, cobalt, iron, chromium, vanadium, palladium, ruthenium, rhodium, molybdenum, tungsten, iridium, silver, gold and platinum. When a substrate made of the above metal is used, the substrate may be subjected to anti-corrosion treatment or insulation treatment.

The inorganic material other than the metal may include at least one selected from the group consisting of calcium carbonate (CaCO ₃ ), talc, and mica.

In one embodiment, the substrate may include an inorganic material other than metal, and more specifically, the substrate may include mica. In such an embodiment, thermal insulation, durability, etc. of the battery insulating sheet may be improved.

The thickness of the substrate may range from about 0.01 mm to about 5 mm, about 0.05 mm to about 3 mm, or about 0.1 mm to about 1 mm. When the substrate having a thickness within the above range is included, the durability of the battery insulating sheet may be improved.

A method for manufacturing a battery insulating sheet according to an embodiment may include the steps of manufacturing a raw material mixture including a powdered dry binder and powdered aerogel particles, and extruding the raw material mixture by using an extruder to manufacture an aerogel layer including a fibrillated polymer matrix in which aerogel particles are distributed and the dry binder.

The method of manufacturing the battery insulating sheet may be entirely performed through a drying process, and the detailed description of the aerogel layer may be the same as above.

In the step of manufacturing a raw material mixture including a powdery dry binder and powdery aerogel particles, detailed descriptions of the dry binder and the aerogel particles may be the same as described above.

In the step of manufacturing the raw material mixture, the dry binder and the aerogel particles may not contain a solvent and may be mixed in a powder phase.

The step of making a raw material mixture may be performed by one or two mixing steps. The step of making a raw material mixture may include a primary dry mixing step and a secondary dry mixing step. The stirring speed in the secondary dry mixing step may be at least about 2 times, in the range of about 2 to about 8 times, or in the range of about 4 to about 6 times, the stirring speed in the primary dry mixing step.

In the primary dry mixing step, the temperature may range from about 20°C to about 65°C, from about 25°C to about 50°C, or from about 25°C to about 35°C, the stirring speed may be about 2000 rpm or less, in the range of about 500 rpm to about 1800 rpm, or in the range of about 800 rpm to about 1300 rpm, and the stirring time may range from about 5 min to about 15 min.

In the secondary dry mixing step, the temperature may range from about 20°C to about 65°C, about 25°C to about 50°C, or about 25°C to about 35°C, the stirring speed may range from about 4000 rpm to about 10,000 rpm, about 4000 rpm to about 8000 rpm, or about 4000 rpm to about 6000 rpm, and the stirring time may range from about 10 min to about 60 min, about 10 min to about 40 min, or about 20 min to about 30 min.

The raw material mixture that has been completed through the primary dry mixing step and the secondary dry mixing step under the above conditions is extruded to form an aerogel layer having aerogel particles distributed in the fibrillated polymer matrix.

In the step of manufacturing the raw material mixture, an agitator can be used for stirring. The agitator may include, for example, a kneader. For example, the agitator may have a structure including a chamber, at least one rotating shaft rotatably arranged in the chamber, and a blade rotatably coupled to the rotating shaft. The blade may be arranged in the longitudinal direction of the rotating shaft. The blade may include at least one selected from, for example, a ribbon blade, a sigma scraper, a jet (Z) blade, a dispersion blade, and a spiral blade. When the blade is included, the aerogel particles and the dry binder can be effectively mixed without any solvent to manufacture a dough-like raw material mixture.

In manufacturing the raw material mixture, the dry binder may be included in the range of about 20 wt % to about 70 wt %, about 30 wt % to about 60 wt %, or about 40 wt % to about 60 wt % of the total amount of the raw material mixture, and the aerogel particles may be included in the range of about 30 wt % to about 80 wt %, about 40 wt % to about 70 wt %, or about 40 wt % to about 60 wt % of the total amount of the raw material mixture. When the raw material mixture is manufactured within the above range, an aerogel layer having desired thermal insulation, heat resistance, flexibility, and low dust characteristics may be manufactured.

In an embodiment, the step of manufacturing the aerogel layer may include introducing a raw material mixture into an extruder, and extruding the raw material mixture in a sheet form.

The step of manufacturing an aerogel layer may be performed at a temperature ranging from about 25° C. to about 150° C., about 30° C. to about 100° C., or about 30° C. to about 70° C. In the step of manufacturing an aerogel layer, the pressure during extrusion may range from about 1 MPa to about 100 MPa, about 20 MPa to about 80 MPa, or about 30 MPa to about 70 MPa. When the raw material mixture is extruded under the above conditions, an aerogel layer having a structure in which aerogel particles are uniformly distributed in a dry binder may be formed.

The method of manufacturing a battery insulating sheet according to an embodiment may be performed through a drying process in which a process solvent is not included, and therefore, an additional process for removing a residual solvent may not be required.

In an embodiment, when the raw material mixture is extruded by an extruder in the step of manufacturing an aerogel layer, the temperature may range from about 20° C. to about 90° C., about 30° C. to about 60° C., or about 35° C. to about 55° C. The pressure during extrusion may range from about 30 MPa to about 70 MPa, about 40 MPa to about 65 MPa, or about 40 MPa to about 60 MPa. When the raw material mixture is extruded under the conditions within the above range, an aerogel layer including a fibrillated polymer matrix in which aerogel particles are dispersed can be manufactured.

The extruder may be, but is not limited to, a known extruder. For example, a single-screw extruder and a twin-screw extruder may be used.

In an embodiment, the method may further include the step of laminating a substrate on the upper surface, the lower surface, or the upper and lower surfaces of the aerogel layer. As an example, a battery insulating sheet may be manufactured by laminating an aerogel layer on a substrate. In another embodiment, a battery insulating sheet may be manufactured by laminating a first substrate and a second substrate on the upper and lower surfaces of the aerogel layer, respectively. The substrate, the first substrate, and the second substrate may be the same as described above.

In the step of laminating the substrate, the substrate may be laminated on the upper surface, the lower surface, or the upper and lower surfaces of the aerogel layer by using an adhesive. The step of laminating the substrate may be performed by applying a common adhesive to form an adhesive layer on the lower surface or the upper and lower surfaces of the aerogel layer and laminating the substrate on the adhesive layer.

The battery module according to the embodiment may include a plurality of battery cells and a battery insulating sheet disposed between the plurality of battery cells. The upper surface and the lower surface of the battery insulating sheet may be disposed to face the battery cells adjacent thereto, respectively.

FIG. 4 is a schematic diagram illustrating a battery insulating sheet between a plurality of battery cells according to an embodiment.

4, the battery insulating sheet 100 according to the embodiment may be formed (or placed) between a plurality of battery cells 200 included in the battery module. The battery insulating sheet 100 may have an upper surface, a lower surface, and an edge side surface between the upper surface and the lower surface. The upper surface and the lower surface of the battery insulating sheet 100 may be arranged (or disposed) to face the battery cells 200 adjacent thereto, respectively. For example, the upper surface and the lower surface of the aerogel layer 110 shown in FIG. 1 may be arranged to face the battery cells 200 formed on the left and right sides in FIG. 4, respectively. As another example, the upper surface of the aerogel layer 110 shown in FIG. 2 and the lower surface of the substrate 120 may be arranged to face the battery cells 200 formed on the left and right sides in FIG. 4, respectively. As yet another example, the lower surface of the first substrate 130 and the upper surface of the second substrate 140 shown in FIG. 3 may be arranged to face the battery cells 200 formed on the left and right sides in FIG. 4, respectively. When the battery insulating sheet 100 according to an embodiment is formed between a plurality of battery cells 200, a battery module capable of substantially blocking the movement of flame or heat from one battery cell to another battery cell is provided, thereby appropriately suppressing the propagation of heat and flame to another battery cell with a higher level of safety, and a battery pack including the battery module.

Hereinafter, specific embodiments will be described. However, the following embodiments are intended to illustrate or describe aspects and features of the present disclosure and should not be construed as limiting the present disclosure. Those skilled in the art can fully infer technically that the contents not described herein will be omitted for description.

Manufacturing of battery insulation sheets

Example 1

1. Manufacture of raw material mixture

The raw material mixture was prepared by mixing powdered polytetrafluoroethylene as a dry binder and aerogel particles (D50 50 μm). The raw material mixture was subjected to primary dry mixing at a stirring speed of 1000 rpm at 25° C. for 10 minutes to prepare a first mixture. Subsequently, the first mixture was further mixed at a stirring speed of 5000 rpm at 25° C. for 20 minutes to prepare a second mixture.

The content of polytetrafluoroethylene was 50 wt % of the total amount of the raw material mixture, and the content of the aerogel particles was 50 wt % of the total amount of the raw material mixture.

2. Manufacturing of aerogel layer

The manufactured second mixture was introduced into an extruder and extruded at a temperature of 45° C. and a pressure of 50 MPa to form an aerogel layer having aerogel particles distributed in a fibrillated polytetrafluoroethylene matrix. The thickness of the aerogel layer was measured to be 2 mm.

3. Manufacturing of battery insulation sheets

The battery insulating sheet was manufactured by laminating a 0.1 mm thick mica sheet (eg, from Famica, Muscovite) on each of the upper and lower surfaces of the aerogel layer using a coating method using an adhesive.

Example 2

A battery insulating sheet was manufactured by using the same method as Example 1, except that the raw material mixture was manufactured to include 20 wt % of polytetrafluoroethylene and 80 wt % of aerogel particles.

Example 3

A battery insulating sheet was manufactured by using the same method as Example 1, except that the raw material mixture was manufactured to include 35 wt % of polytetrafluoroethylene and 65 wt % of aerogel particles.

Example 4

A battery insulating sheet was manufactured by using the same method as Example 1, except that the raw material mixture was manufactured to include 65 wt % of polytetrafluoroethylene and 35 wt % of aerogel particles.

Example 5

A battery insulating sheet was manufactured by using the same method as in Example 1, except that aerogel particles having an average particle size D50 of 5 μm were used and the raw material mixture was manufactured to include 80 wt % of polytetrafluoroethylene and 20 wt % of the aerogel particles.

Example 6

A battery insulating sheet was manufactured by using the same method as in Example 1, except that aerogel particles having an average particle size D50 of 100 μm were used.

Comparative Example 1

1. Manufacture of aerogel compositions

The aerogel composition is manufactured by introducing polyvinyl alcohol (eg, from Sigma Aldrich) as an aqueous binder, polytetrafluoroethylene as a dry binder, and aerogel particles into an ultrapure solvent and mixing them.

The solid content of the aerogel composition was measured to be 85 wt% aerogel particles, 10 wt% polyvinyl alcohol, and 5 wt% polytetrafluoroethylene.

2. Manufacturing of battery insulation sheets

The slurry for making the aerogel composition is applied to a 0.1 mm thick mica sheet (e.g., from Famica, muscovite), another 0.1 mm thick mica sheet is laminated thereon in a sandwich manner, and coated by using a roll-rolling method. Subsequently, an aerogel layer is formed by drying to make a battery insulating sheet.

Comparative Example 2

A battery insulating sheet was manufactured using the same method as in Comparative Example 1, except that an aerogel composition including 50 wt % of aerogel particles and 50 wt % of polytetrafluoroethylene as solid content was manufactured by adjusting the input amount of raw materials. In this case, since polytetrafluoroethylene was difficult to disperse, a battery insulating sheet could not be manufactured.

Comparative Example 3

A battery insulating sheet was manufactured using the same method as in Comparative Example 1, except that an aerogel composition including 85 wt % of aerogel particles, 5 wt % of polyvinyl alcohol, and 10 wt % of polytetrafluoroethylene as solid content was manufactured by adjusting the input amounts of raw materials. In this case, since polytetrafluoroethylene was difficult to disperse, the battery insulating sheet could not be manufactured.

Experimental example

Experimental Example 1: Evaluation of thermal insulation properties

The thermal insulation property of each of the battery insulating sheets manufactured in Examples 1 to 6 and Comparative Examples 1 to 3 was evaluated using the following method, and the results are shown in Table 1 below.

The measurement of thermal conductivity (mW/mK) at room temperature (23±5° C.) was performed by cutting each battery insulating sheet into samples of 125 mm to 150 mm width and 125 mm to 150 mm length, and measuring the thermal conductivity of the samples at room temperature (23±5° C.) by using HFM 436 Lambda equipment from NETZSCH. The lower the thermal conductivity at room temperature, the better the thermal insulation of the battery insulating sheet.

Experimental Example 2: Evaluation of Dust Content

The dust content of each of the battery insulating sheets manufactured in Examples 1 to 6 and Comparative Examples 1 to 3 was evaluated using the following method, and the results are shown in Table 1 below.

The dust content test was conducted by measuring the weight reduction rate of each battery insulating sheet under vibration at 24 Hz/3 mm for 6 hours using a vibration tester (ASTM C592-04).

- Sample preparation, including preparation of 12 inch x 12 inch battery insulation sheets.

-Weight reduction rate [%] = [(weight of battery insulating sheet before evaluation) - (weight of battery insulating sheet after evaluation)] / (weight of battery insulating sheet before evaluation) × 100

Experimental Example 3: Evaluation of Flexibility

The flexural modulus of each of the battery insulating sheets manufactured in Examples 1 to 6 and Comparative Examples 1 to 3 was evaluated using the following method, and the results are shown in Table 1 below.

The flexural modulus (MPa) was measured by making samples from each battery insulating sheet according to ASTM D790, and the flexural modulus of the samples was measured by using UTM (UT-005E) from MTDI. A 3-point bending analysis method was used. The manufactured sample was placed on a support, a force was applied to the center of the sample at a speed of 1 mm/min to 10 mm/min to record the load, and the initial slope value was measured by dividing the load by 15% strain to measure the flexural modulus at 15% strain. The lower the flexural modulus, the more flexible the battery insulating sheet.

Table 1

Referring to the above Table 1, the examples exhibited excellent thermal insulation, dust content, and flexibility. It can be expected that the heat resistance of the battery insulating sheet is excellent because the battery insulating sheet includes a high content of a dry binder having excellent heat resistance.

With reference to Examples 1 to 6, thermal insulation, dust content, and flexibility vary according to the content of aerogel particles and polytetrafluoroethylene. It can be seen that when the average particle size of the aerogel particles ranges from 50 μm to 100 μm and the content of polytetrafluoroethylene ranges from 20 wt % to 65 wt %, the physical property measurement results are better.

Referring to Comparative Example 1, it can be seen that when the aerogel layer is formed by a wet process using a solvent, although the aerogel particle content is higher, the thermal insulation is similar to that of Example 2, and the flexibility and dust content are also reduced. When the aerogel layer is manufactured by a wet process, it can be seen from Comparative Examples 1 to 3 that it is impossible to contain more than 5wt% of polytetrafluoroethylene, and when the content of polytetrafluoroethylene exceeds the above value, it is difficult to form an aerogel layer due to dispersibility problems. It can be seen that, unlike the embodiment, when the aerogel layer is manufactured by a wet process, it is difficult to manufacture a battery insulating sheet with a thin thickness.

Therefore, it can be seen that when the aerogel composition according to the embodiment is used, thermal insulation, heat resistance, flexibility, and low dust characteristics are excellent.

As is apparent from the above description, the battery insulating sheet according to the embodiment may include a fibrillated polymer matrix in which aerogel particles are distributed by using a heat-resistant drying binder and a drying process of aerogel particles, thereby providing the battery insulating sheet with excellent thermal insulation, heat resistance, low dust properties and flexibility.

Although the embodiments of the present disclosure are described above, the present disclosure is not limited thereto, and it is contemplated that various modifications may be made within the scope of the claims and their equivalents, the detailed description of the embodiments, and the accompanying drawings, which also belong to the scope of the present disclosure.

Claims (18)

1. A battery insulating sheet, comprising an aerogel layer, wherein the aerogel layer comprises: a fibrillated polymer matrix comprising a dry binder; and Aerogel particles are distributed in the fibrillated polymer matrix. 2 . The battery insulating sheet of claim 1 , wherein the dry binder comprises a fluorinated binder, wherein the fluorinated binder is at least one selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride-hexapropylene copolymer, and polyvinylidene fluoride. 3. The battery insulating sheet according to claim 1, wherein The fibrillated polymer matrix accounts for 10 wt% to 90 wt% of the total amount of the aerogel layer, and The aerogel particles account for 10 wt % to 90 wt % of the total amount of the aerogel layer. 4 . The battery insulating sheet of claim 1 , wherein the aerogel particles have a BET specific surface area ranging from 500 to 1,000 ^{m 2 /} g. 5 . The battery insulation sheet of claim 1 , wherein the aerogel particles have an average particle size D50 ranging from 5 μm to 100 μm. 6. The battery insulation sheet of claim 1, wherein the aerogel particles are dispersed inside the fibrillated polymer matrix. 7. The battery insulation sheet according to claim 1, wherein the aerogel layer satisfies the following formula 1: [Formula 1] 0.1≤W _FB /T _PM ≤18 Wherein W _FB is the content of the dry binder in wt % of the total amount of the aerogel layer, and T _PM is the average particle size of the aerogel particles in μm. 8 . The battery insulating sheet of claim 1 , further comprising a substrate on an upper surface, a lower surface, or both of the upper and lower surfaces of the aerogel layer. 9 . The battery insulating sheet of claim 1 , wherein the battery insulating sheet has a structure in which a first substrate, the aerogel layer, and a second substrate are sequentially laminated. 10. A method for manufacturing a battery insulating sheet, the method comprising: producing a raw material mixture comprising a powdered dry binder and powdered aerogel particles; and by extruding the raw material mixture using an extruder to produce an aerogel layer, The aerogel layer comprises a fibrillated polymer matrix, the fibrillated polymer matrix comprises the dry binder, and the aerogel particles are distributed in the fibrillated polymer matrix. 11. The method of claim 10, wherein the manufacturing of the raw material mixture comprises a primary dry mixing step or a primary dry mixing step and a secondary dry mixing step. 12. The method of claim 10, wherein said manufacturing of said raw material mixture comprises a primary dry mixing step and a secondary dry mixing step, and The stirring speed in the secondary dry mixing step is at least twice the stirring speed in the primary dry mixing step. 13. The method according to claim 11 or 12, wherein in the primary dry mixing step, the temperature ranges from 20°C to 65°C, the stirring speed is 2000 rpm or less, and the stirring time ranges from 5 min to 15 min, and Wherein, in the secondary dry mixing step, the temperature ranges from 20°C to 65°C, the stirring speed ranges from 4000rpm to 10,000rpm, and the stirring time ranges from 10min to 60min. 14. The method of claim 10, wherein the manufacturing of the aerogel layer comprises introducing the raw material mixture into the extruder and extruding the raw material mixture into a sheet form. 15. The method of claim 10, wherein the manufacturing of the aerogel layer is performed at a temperature ranging from 25°C to 150°C and a pressure ranging from 1 MPa to 100 MPa. 16 . The method of claim 10 , further comprising laminating a substrate on an upper surface, a lower surface, or both of the upper and lower surfaces of the aerogel layer. 17. The method of claim 10, wherein a first substrate and a second substrate are laminated on an upper surface and a lower surface of the aerogel layer, respectively. 18. A battery module, comprising: a plurality of battery cells; and A battery insulating sheet according to any one of claims 1 to 9 or a battery insulating sheet manufactured by the method according to any one of claims 10 to 17 between the plurality of battery cells, The upper surface and the lower surface of the battery insulating sheet respectively face adjacent battery cells among the plurality of battery cells.