Protective element

Abstract

The invention relates to a protective element (10) comprising at least one first layer (1) and at least one second layer (2), the first layer (1) being made of an elastomeric material, and the second layer (2) forming a fireproof ply (3).

Description

Technical Field

[0001] The invention relates to a protective element comprising at least one first layer and at least one second layer. Background Art

[0002] Such a protective element is known from DE 10 2018 113 815 A1. The known protective element is used in an energy storage system, wherein the energy storage system comprises a housing in which a plurality of storage cells are arranged.

[0003] Energy storage systems, in particular rechargeable electrical energy storage devices, are widely used, primarily in mobile systems. Rechargeable electrical energy storage devices are used, for example, in portable electronic devices such as smartphones or laptops. In addition, rechargeable electrical energy storage devices are increasingly used to supply energy to electric vehicles. A wide range of electric vehicles is conceivable here, in addition to cars, for example, two-wheeled vehicles, vans or trucks are also conceivable. Applications in robots, ships, aircraft and mobile working machines are also conceivable. Other fields of application of electrical energy storage systems are stationary applications, for example in backup systems, in grid stabilization systems and for storing electrical energy from renewable energy sources.

[0004] Energy storage systems frequently used here are rechargeable energy storage systems in the form of lithium-ion batteries. Like other rechargeable electrical energy storage devices, lithium-ion batteries usually have a plurality of storage cells, which are installed together in a housing. A plurality of storage cells electrically connected to one another are usually assembled to form a module.

[0005] In this case, the energy storage system is not only a lithium-ion battery. Other rechargeable battery systems, such as lithium-sulfur batteries, solid-state batteries, sodium-ion batteries or metal-air batteries are also conceivable energy storage systems. In addition, supercapacitors are also conceivable as energy storage systems.

[0006] Energy storage systems in the form of rechargeable energy storage devices have the highest capacity and the best power absorption and power release only in a limited temperature range. If the optimal operating temperature range is exceeded or fallen below, the capacity, power absorption capacity and power release capacity of the energy storage device will drop significantly, and the functionality of the energy storage device will be impaired. In addition, excessively high temperatures can irreversibly damage the energy storage device. Therefore, both permanent elevated temperatures and short-term temperature peaks should be absolutely avoided. For example, in lithium-ion batteries, the temperature should not exceed more than 50°C permanently, and short-term temperature peaks should not exceed more than 80°C.

[0007] Especially when used in cars, the energy storage system is required to have a fast charging capability. Here, the battery constituting the energy storage system should be fully or almost fully charged in a short time, for example, within 15 minutes. Since the efficiency of the charging system is about 90% to 95%, a large amount of heat is released in the energy storage system during the charging process, and this heat must be discharged from the energy storage system. Under normal operating conditions, this heat will not be released. Therefore, it is necessary to design the cooling system of the energy storage system so that the heat generated during the charging process can be absorbed.

[0008] Excessively high temperatures can lead to irreversible damage to the energy storage system. In this regard, so-called thermal runaway is known, especially in lithium-ion cells. In this process, high thermal energy and gaseous and particulate decomposition products are released in a short time, thereby forming high pressure and temperature in the housing. Here, the pressure may be greater than 10 bar and the temperature may be as high as 1,000°C. The particles may have high temperatures and high abrasiveness. In prismatic cells, the release occurs particularly in the area of ​​the rupture, while in soft-pack cells, the location of the release is uncertain. This effect is particularly problematic in energy storage systems with high energy density, such as those required, for example, for providing electrical energy in electric vehicles. Due to the gradual increase in the energy of individual cells and the increase in the packaging density of the cells arranged in the housing, the problem of thermal runaway becomes more and more serious. In addition to thermal runaway, there is also the risk of thermal propagation. Heat propagation preferentially propagates the thermal runaway in a cascading manner to adjacent cells and (due to hot particle flow and arcing) also to distant cells.

[0009] Likewise, it should be possible to avoid flame breakdown or at least to achieve a significant time delay of at least 5 minutes. On the one hand, the housing of the energy storage system should be protected against the discharge of dangerous particles. Otherwise, in the case of a vehicle, these particles could enter the driver's cabin. On the other hand, components to be protected adjacent to the housing of the energy storage system, such as other electronic components, should be protected. The protective element should prevent the particle stream emitted from the battery cell from damaging the components to be protected or delay the occurrence of this as long as possible. Summary of the invention

[0010] The object of the present invention is to provide a protective element which allows improved operational safety.

[0011] This object is achieved by the features of claim 1. The dependent claims relate to advantageous embodiments.

[0012] The protective element according to the invention comprises at least one first layer and at least one second layer, wherein the first layer consists of an elastomeric material and wherein the second layer forms a fire protection ply.

[0013] In this embodiment, the thermal conductivity of the first layer is limited by the material properties of the elastomer material. The elastomer material is designed such that it preferably has a thermal conductivity of a maximum of 3 W / (m·K). Due to the limited thermal conductivity, the heat transfer through the protective element is reduced and the protective element has thermal insulation properties.

[0014] In the case of thermal runaway and also in the case of heat propagation, the protective element according to the invention can shield the housing wall from hot and possibly particle-laden and abrasive gas, liquid and / or vapor flows. The housing and / or the module walls arranged therein are usually made of deep-drawn steel sheets, aluminum, thermoplastics, thermosetting plastics or composite materials. The protective element prevents the housing or module walls from being damaged in the event of damage, resulting in partial melting through, crack formation or structural weakening. In addition, the protective element prevents the flame, the hot gas particle flow from escaping prematurely and uncontrolled, and therefore also prevents the carrier from catching fire uncontrolled, and in the case of electric vehicles, prevents the entire vehicle from catching fire.

[0015] Furthermore, the elastomeric material is preferably partially or completely crosslinked. Crosslinking describes the extent to which the macromolecular chains of the elastomeric material are crosslinked with one another and form a network. The elastic properties of the material can be influenced by crosslinking. Preferably, crosslinking is carried out so that the elastomeric material is elastic. As a result, on the one hand, it is possible for the protective element to have a desired, often even necessary flexibility for installation and to be specifically modified and, for example, bendable. This simplifies assembly. Furthermore, in an elastic design, the protective element can absorb changes in the volume of adjacent components.

[0016] Furthermore, the elastomeric material is preferably designed such that the protective element has no tendency to creep, but at least has a reduced tendency to creep. As a result, the protective element has a long service life and can be used even under long-term stress conditions.

[0017] Suitable crosslinking systems include, in particular, peroxide vulcanization, platinum-catalyzed addition crosslinking, radiation crosslinking or room temperature vulcanization systems.

[0018] An advantageous design of the present invention provides that the first layer contains a silicone elastomer compound. The silicone elastomer compound has high heat resistance. This achieves high temperature resistance of the protective element. The silicone elastomer compound preferably comprises a liquid silicone elastomer (LSR) or a high temperature crosslinking silicone elastomer compound (HTV silicone elastomer compound). In such a design, it is achieved that the thermal degradation products form an inorganic film or protective layer in the event of a fire, which is thermally stable and non-conductive and protects the remaining elastomer underneath with its protective properties. This further improves the operational safety of the protective element. In addition, the protective element thus has only a slight tendency to peel off.

[0019] The first layer may contain a first filler, wherein the first filler is composed of an organic material. The organic material includes, for example, materials such as polyimide, thermosetting plastic, polyacrylonitrile (PAN), oxidized PAN, aramid, cotton or cellulose. These materials have high temperature stable properties and improve the resistance of the protective element to temperature loads.

[0020] The first layer may contain a second filler, wherein the second filler is composed of an inorganic material. The first group of inorganic fillers is, for example, glass or ceramic, in particular basalt, alumina, mullite or ZrO 2 The second group of inorganic fillers comprises, for example, oxides, hydroxides or oxyhydroxides. Minerals such as mica, silicates, alkaline earth metal carbonates or silicon dioxide are also conceivable. In principle, the second filler can consist of a combination of the abovementioned materials.

[0021] The first filler and / or the second filler may comprise a filler in the form of fibers. Here, the elastomeric material forms the elastomeric matrix and the fibers are preferably connected to the elastomeric matrix by vulcanization. As a result, the advantageous properties of the fiber material can be combined with the advantageous properties of the elastomeric matrix. Preferably, the fibers have a fiber length between 5 μm and 50 mm and a fiber diameter between 2 μm and 500 μm.

[0022] The first filler and / or the second filler may also contain other fibers, whose fiber length and / or fiber diameter are outside the above-defined ranges. Preferably, all fibers of the first filler and / or the second filler have a fiber length and / or fiber diameter within the defined ranges. Preferably, at least 90% of the fibers, based on the total surface area of ​​all fibers, are surrounded by the elastomer matrix. The fibers preferably contain organic material and / or inorganic material of the first group.

[0023] The first filler and / or the second filler may comprise a filler in the form of particles. The elastomeric material forms an elastomeric matrix. Preferably, at least 90% of the particles are surrounded by the elastomeric matrix, based on the total surface area of ​​all particles. Preferably, the particles have a spherical, flaky or amorphous shape. In addition, the particles preferably have endothermic properties. This endothermic property can be achieved, for example, by phase change or by chemical reaction. The desired endothermic temperature range is between 100 and 800° C. As a result, the temperature characteristics of the protective element can be further improved. The particles preferably contain a second group of inorganic materials.

[0024] The first layer may contain an adhesion promoter. In this embodiment, preferably silanes or resins are used as adhesion promoters. This can achieve an improved connection between the first and / or second filler and the elastomer matrix.

[0025] Fire barrier layers can include textile fabrics Preferred textile fabrics are woven fabrics and knitted fabrics, wherein the textile fabric contains fibers. Fabrics consisting of randomly arranged fibers, such as felt or nonwovens, are also conceivable. Preferably, at least 10% of the textile fabric, based on the total surface area of ​​the textile fabric, is surrounded by the elastomer matrix.

[0026] The fireproof layer may comprise an inorganic material. Inorganic materials are, for example, glass or ceramics, in particular basalt, alumina, silicates or ZrO 2 .

[0027] The fireproof layer may comprise organic materials, such as polyimide, thermosetting plastic, polyacrylonitrile (PAN), oxidized PAN, aramid, cotton or cellulose, which have the characteristics of high temperature stability.

[0028] The fireproof layer may also contain metal material. Preferably, the fireproof layer contains metal wire and / or metal fabric.

[0029] The protective element may have a surface structured portion. Preferably, the protective element has a surface structured portion in a free surface area. This structured portion improves the deformability of the protective element on the one hand and also has a thermal effect on the other hand. Depending on the configuration of the macroscopic structured portion, a channel can be generated between the protective element and the adjacent component, through which the heat emitted by the adjacent component can be discharged. It is also conceivable that the structured portion will have a thermal insulation effect. Accordingly, it is conceivable that the surface structured portion of the protective element forms a flow-guiding structure. The flow-guiding structure also enables the gas escaping from the storage unit to be discharged in the event of thermal runaway.

[0030] The protective element can be constructed in a planar shape. The planar protective element can preferably be constructed as a web product. In addition, the protective element preferably has such elastic deformability that the protective element or a preform for manufacturing the protective element can be supported on a reel. This further improves the operability of the protective element. The protective element preferably has a thickness of 0.3 mm to 5 mm. The protective element particularly preferably has a thickness of 0.8 mm to 2.5 mm. This further improves the deformability of the protective element, so that the protective element has a desired elastic response when adjacent components expand and contract. In addition, the protective element has improved tolerance compensation due to its deformability.

[0031] The protective element can be configured as a molded part. In this configuration, the protective element can in particular form a fireproof seal.

[0032] The protective element is preferably configured such that under the influence of heat, for example in the event of a fire, no electrically conductive particles are generated or released on the side facing the flame.

[0033] The invention also relates to an arrangement (Anordnung), which comprises a protective element, a combustible element and an element to be protected from fire, wherein the protective element is arranged between the combustible element and the element to be protected from fire, wherein the fireproof layer of the protective element is arranged on the side facing away from the combustible element. It has been surprisingly found that a particularly good flame retardant effect is obtained if the first layer formed by the elastomeric material faces the combustible element (for example, the rupture of the battery cell). It has been found that in this arrangement, the fire protection effect is improved compared to an arrangement in which the second layer forming the fireproof layer faces the combustible element. One reason for this is that the elastomeric material of the first layer already has excellent flame retardant properties, while the high temperature resistant second layer forms a supporting layer and ensures mechanical stability even under large thermal loads. The element to be protected from fire can be a medium-conducting or electrically conductive device.

[0034] Furthermore, the arrangement according to the invention has the advantage that a fire protection layer consisting of a fiber material can be placed between the first layer and the housing. This avoids contamination by fibers that may be released. Furthermore, due to the smooth first layer facing outwards, the protective element is not susceptible to contamination.

[0035] In the described arrangement, the protective element protects the element to be protected, in particular from being penetrated by a flame emitted from the combustible element. The protective element at least ensures a significant time delay, thereby greatly increasing operational safety.

[0036] The invention also relates to an accumulator system, comprising a protective element and a housing, in which at least one storage unit is arranged, wherein the protective element is arranged between the at least one storage unit and the housing, wherein the fireproof layer is arranged on the side facing away from the storage unit. This corresponds to a specific design of the arrangement described above, wherein the storage unit is a combustible element and the housing is an element to be protected from fire. This arrangement can prevent or delay the escape of flames and / or gases from the housing, in particular in the event of thermal runaway (thermal runaway or heat propagation).

[0037] The protective element can be produced by calendering in combination with continuous vulcanization. During calendering, the protective element is guided through the gap between a plurality of rollers arranged one above the other. This preferably produces a planar protective element. It is also conceivable to use an injection molding method to produce the protective element as a molded part. In addition, extrusion is conceivable as a production process for special profile geometries of the protective element. Depending on the production process, the surface of the protective element can have embossing in the form of contours or ribs.

[0038] Preferably, the thickness of the protective element increases by less than 50% under the action of heat, especially in the event of a fire. This distinguishes the protective element according to the invention from a layer with an intumescent configuration. The heat preservation mechanism of the intumescent layer is that, under thermal load, a thermal insulation pad consisting of thermal degradation products is formed in situ. However, in the case of the present invention, this pad will disadvantageously hinder the discharge of gases released from the battery cell. This also increases the risk of important components, such as exhaust channels, being blocked. On the one hand, this in turn can lead to a significant increase in pressure in the accumulator system and cause the accumulator system to rupture. On the other hand, heat accumulation may occur in a blocked accumulator system, which can cause adjacent components to be subjected to severe high temperature loads.

[0039] The protective element may comprise at least one third layer. Preferably, a third layer is provided, which may be configured in the form of a coating applied to the protective element. In this design, the third layer forms the outer layer of the protective element. The protective element may be provided with a third layer on one side, multiple sides or all sides. The third layer may be applied by spraying or scraping. Preferably, the third layer comprises a polymer material, such as a silicone elastomer or a polyurethane. In addition, the third layer may comprise an expandable and / or ceramic material, which is embedded in the material of the third layer. The protection of the protective element against thermal and / or mechanical loads is further improved by the third layer.

[0040] Some embodiments of the protection element according to the present invention are described in detail below with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The figure schematically shows:

[0042] Figure 1 A cross-sectional view showing a protective element;

[0043] Figure 2 a cross-sectional view showing the arrangement of the protection element;

[0044] Figure 3 A cross-sectional view of a protective element with a coating is shown. DETAILED DESCRIPTION

[0045] Figure 1 A cross-sectional view of a protective element 10 is shown. The protective element 10 comprises a first layer 1 and a second layer 2, wherein the first layer 1 consists of an elastomeric material and wherein the second layer 2 forms a fire barrier ply 3.

[0046] In the present embodiment, the elastomeric material of the first layer 1 has a thermal conductivity of 1.5 W / (m·K). Furthermore, the elastomeric material is partially crosslinked in this embodiment in order to achieve good assembly properties due to the elastic properties. The elastomeric material is further designed to be elastic in order to absorb volume changes of adjacent components. Furthermore, the elastomeric material has a reduced tendency to creep, whereby the protective element 10 is suitable for withstanding long-term loads.

[0047] According to the present design, the first layer 1 is made of an organic silicone elastomer. The organic silicone elastomer has high heat resistance. In the present design, the first layer 1 contains a first filler, which is oxidized polyacrylonitrile. In alternative designs, other organic fillers may also be used, such as thermosetting plastics, polyacrylonitrile, polyimide, aramid, cotton or cellulose.

[0048] In the present embodiment, the first filler comprises fibers. The elastomeric material is used as the elastomeric matrix and the fibers are connected to the elastomeric matrix by vulcanization. The fibers are present as a fiber mixture with a fiber length between 2 μm and 50 mm and a fiber diameter between 2 μm and 400 μm. The fibers are mostly embedded in the matrix and are 95% surrounded by the elastomeric matrix.

[0049] The first layer 1 comprises a second filler, in this case mica. In alternative embodiments, other inorganic fillers can also be used, such as ceramics (especially basalt, alumina, mullite, phlogopite, muscovite or ZrO 2 ), glass or inorganic oxides, hydroxides or oxyhydroxides, as well as minerals, silicates, alkaline earth metal carbonates, borates or silicon dioxide.

[0050] The second filler is present in the form of particles. The particles are mostly embedded in the matrix of the elastomer material and are at least 95% surrounded by the elastomer matrix. The particles have a spherical shape. In addition, the particles have heat absorption properties, thereby further improving the temperature properties of the protective element 10.

[0051] In the present design, the first layer 1 contains an adhesion promoter, which is used to improve the connection between the first filler and the second filler and the elastomer matrix.

[0052] The fire protection layer 3 comprises a textile fabric, which is designed as a textile fabric in this case. The textile fabric is only partially embedded in the matrix of the elastomeric material and is only 20% surrounded by the elastomeric matrix.

[0053] In the present embodiment, the fireproof layer 3 comprises an organic material, in this case oxidized polyacrylonitrile. In alternative embodiments, thermosetting plastics, polyacrylonitrile (PAN), polyimide, aramid, cotton or cellulose may also be used, but inorganic materials such as ceramics (especially basalt, alumina, mullite, phlogopite, muscovite or ZrO 2 ) or glass. In alternative designs, metal materials may also be considered, so that the fireproof layer 3 may comprise metal wires and / or metal fabrics.

[0054] In the present design, the protective element 10 has a surface structuring in the free surface area. The surface structuring improves the deformability of the protective element 10 on the one hand and also has a thermal effect on the other hand. In addition, the protective element 10 can be easily mounted on the housing, for example by means of an adhesive.

[0055] In the present design, the protective element 10 is constructed in a planar shape and exists as a web product. In an alternative design, the protective element 10 can also be constructed as a molded part. Due to the elastic deformability of the protective element 10, the protective element 10 can be supported on a reel in particular. In the present design, the protective element 10 has a thickness of 1.5 mm.

[0056] The protection element 10 is manufactured by calendaring combined with continuous vulcanization. Alternatively, the protection element 10 is manufactured by extrusion combined with continuous vulcanization.

[0057] In the present embodiment, the protective element 10 increases in thickness by at most 25% during a fire.

[0058] Figure 2 Shown in Figure 1 20 of the arrangement of the protective element 10 shown in FIG. In addition to the protective element 10, the arrangement 20 also includes a combustible element 4 and an element 5 to be protected from fire. The protective element 10 is arranged between the combustible element 4 and the element 5 to be protected from fire. The fireproof layer 3 of the protective element 10 is arranged on the side facing away from the combustible element 4. The fireproof layer 3 of the protective element 10 is therefore arranged on the side facing the element 5 to be protected from fire. In this arrangement 20, the protective element 10 in particular protects the element 5 to be protected from fire from being penetrated by the flame ejected from the combustible element 4. The protective element 10 at least ensures a significant time delay.

[0059] exist Figure 2 The arrangement 20 shown in the figure forms an energy storage system, which is equipped with one or more protective elements 10. Here, the combustible element 4 is an energy storage unit, and the element 5 to be protected from fire is a housing. The protective element 10 is arranged between the storage unit and the housing, wherein the fireproof layer 3 is arranged on the side facing away from the storage unit. In addition, the protective element 10 can protect other components of the energy storage system, such as control devices, conductive lines or coolant pipes.

[0060] The protective element 10 prevents excessive thermal loading of the element 5 to be protected from fire, i.e. the housing, in the event of damage. The protective element 10 is designed in such a way that it increases in thickness by up to 50% under the action of heat, in particular in the event of a fire. This prevents the problem of the protective element 10 blocking the exhaust duct in the event of damage.

[0061] Figure 3 Shown in Figure 1 , which has a third layer 6. In the present design, the third layer 6 comprises a matrix, wherein the matrix comprises polyurethane. According to another design, the matrix comprises silicone. In addition, the third layer 6 comprises an expanded and ceramic material embedded in the matrix. The protection of the protective element 10 against thermal and mechanical loads is further improved by the third layer. In the present design, the third layer 6 is applied to the protective element 10 from both sides as a coating of the protective element 10.

Claims

1. A protective element (10) comprising at least one first layer (1) and at least one second layer (2), wherein the first layer (1) consists of an elastomeric material and wherein the second layer (2) forms a fire barrier ply (3).

2. The protection element according to claim 1, characterized in that: The first layer (1) comprises a silicone elastomer.

3. The protection element according to claim 1 or 2, characterized in that: The first layer (1) comprises a first filler, wherein the first filler is composed of an inorganic material.

4. The protection element according to any one of claims 1 to 3, characterized in that: The first layer (1) comprises a second filler, wherein the second filler is composed of an organic material.

5. The protection element according to any one of claims 1 to 4, characterized in that: The first filler and / or the second filler comprises a filler in the form of fibers.

6. The protection element according to any one of claims 1 to 5, characterized in that: The first filler and / or the second filler comprises a filler in the form of particles.

7. The protection element according to any one of claims 1 to 6, characterized in that: The first layer (1) comprises an adhesion promoter.

8. The protection element according to any one of claims 1 to 7, characterized in that The fireproof layer (3) comprises a textile fabric.

9. The protection element according to any one of claims 1 to 8, characterized in that: The fireproof layer (3) comprises an inorganic material.

10. The protection element according to any one of claims 1 to 8, characterized in that The fireproof layer (3) comprises organic material.

11. The protection element according to any one of claims 1 to 10, characterized in that The fireproof layer (3) comprises a metal material.

12. The protection element according to any one of claims 1 to 11, characterized in that: The protective element (10) has a surface structuring.

13. The protection element according to any one of claims 1 to 12, characterized in that The protective element (10) is designed to be flat.

14. The protection element according to any one of claims 1 to 13, characterized in that The protective element (10) is designed as a molded part.

15. The protection element according to any one of claims 1 to 14, characterized in that The thickness of the protection element (10) increases by less than 50% under the action of heat.

16. An arrangement (20), comprising a protective element (1), a combustible element (4) and an element to be protected from fire (5) according to any one of the preceding claims, wherein the protective element (1) is arranged between the combustible element (4) and the element to be protected from fire (5), and wherein the fireproof layer (3) of the protective element (1) is arranged on a side facing away from the combustible element (4).

17. The arrangement according to claim 16, characterized in that The element (5) to be protected against fire is a medium-conducting or electrically conductive device.

18. An accumulator system, comprising a protection element (1) according to any one of claims 1 to 15 and a shell, at least one storage unit being arranged in the shell, wherein the protection element (1) is arranged between the at least one storage unit and the shell, and wherein the fireproof layer (3) is arranged on a side facing away from the storage unit.

19. An accumulator system according to claim 18, wherein the accumulator system further comprises a combustible element (4) and an element to be protected from fire (5), wherein the protective element (1) is arranged between the combustible element (4) and the element to be protected from fire (5), wherein the fireproof layer (3) of the protective element (1) is arranged on a side facing away from the combustible element (4).

20. The accumulator system according to claim 19, characterized in that The element (5) to be protected against fire is a medium-conducting or electrically conductive device.

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