Flame-resistant shield for battery modules on battery electric vehicles

Abstract

A flame-resistant shielding blank for covering multiple sides of a battery pack or battery module, the flame-resistant shielding blank comprising a main plate and at least one flap cut from the same blank of material, the main plate and the at least one flap being adjacent to each other and connected, the connection comprising at least one bridge element that at least partially breaks or deforms when the flame-resistant shielding blank is folded into its final shape.

Description

[Technical Field]

[0001] Flame-resistant shield blanks and flame-resistant shields formed from the flame-resistant shield blanks, as well as methods for making the same. [Background technology]

[0002] Flame-resistant shields that cover battery modules or full battery packs within a traction battery box are known in the industry. Such flame-resistant shields are needed to prevent any debris, fire, or smoke from escaping the battery box in the event of a battery thermal runaway. In a thermal runaway event, a defect in the battery can result in contact between chemical phases within the stacked batteries in a chemical fire that generates its own oxygen and is difficult to contain. Not only can the overall temperature rise to a high level very quickly, but an internal explosive reaction can also throw material against the enclosure walls. Therefore, the primary reason for a complete enclosure and internal flame-resistant shield is to prevent further damage to the surroundings from flying objects, fire, fumes, or debris.

[0003] Given the severity of such a thermal runaway event, the materials used must be highly impact-resistant and not subject to any cracking or breakage during the thermal event, which could result in additional damage. Therefore, all materials used are in the form of very rigid plates with a high content of inert fiber fillers, preferably composite materials with glass fiber or endless filaments. While these materials can be formed into 3D structures, the limited space provided within the battery box around the battery module or battery pack, and the resulting lack of draft angle of the material, make it difficult to achieve a good conformal structure. For this reason, today these materials are primarily used as flat top covers over battery cells, modules, or full packs within the battery box. They are often located underneath the actual battery box lid. While battery boxes are made of thick metal, the primary purpose of the flame-resistant shield is to protect against any flames, impact debris, and the heat itself.

[0004] Current materials used to make flame-resistant shields are so rigid that standard folding techniques cannot be used because the occurrence of fold lines is unpredictable and any fold line can result in a weak spot in the material. Unpredictable weak areas can cause the part to fail prematurely during a thermal runaway event.

[0005] Finished 3D structures are more costly to logistic and transport because they require a large shipping volume per piece and are difficult or expensive to stack efficiently. At the same time, breakage or damage to the formed parts can compromise their final fit as a cover.

[0006] Due to the actual nature of thermal runaway events, there is still a need for additional three-dimensional cover options that can fit into tight spaces and optimize transportation. Therefore, the goal is to provide an alternative solution that maintains the level of protection at the material level, but allows the cover to extend to multiple sides of the battery module or pack. Summary of the Invention

[0007] The objects of the present invention are achieved by a flame-resistant shielding blank that covers multiple sides of a battery pack or battery module, a flame-resistant shield produced using the flame-resistant shielding blank, and a method for producing the flame-resistant shielding blank and the flame-resistant shield.

[0008] In particular, the present invention provides a flame-resistant shielding blank comprising a main panel and at least one flap cut from a single blank of material, wherein the main panel and the at least one flap are connected adjacent to each other, and the connection comprises at least one bridge element that at least partially breaks or deforms when the flame-resistant shielding blank is folded into its final shape.

[0009] Surprisingly, it is possible to create a flame resistant shielding blank comprising a plurality of plates, with adjacent plates remaining connected to one another by bridge elements.

[0010] For clarity, the flaps and main panels are all made of the same material and can be seen as multiple plates connected to adjacent plates by connecting bridges, which together form a single flame-resistant shield blank in a distinct pattern that can be folded into a flame-resistant shield having a desired 3D shape. The use of main panels and flaps enables a folding and forming method by defining a base or reference plane from which the folding proceeds to create the final form. However, a single flame-resistant shield form may have different possibilities for the flame-resistant shield blank and optimized cutting and folding methods, offering one or more options or combined options to achieve the same form. For example, nesting two forms to achieve the same final flame-resistant shield may be used to achieve optimized material utilization.

[0011] Preferably, the material blank comprises at least one rigid flame-resistant layer, which may consist of a fibrous material, such as a woven or nonwoven fabric, impregnated with a thermoplastic or thermosetting material, so that the final layer is flame-resistant up to a temperature of at least 1100°C.

[0012] A preferred flame-resistant shielding blank according to the present invention may have each flap separated from the main plate by a partial cut through at least the rigid layer, leaving a bridge element in the rigid layer as a connecting element, which partial cut line serves as a folding line to form the final flame-resistant shield shape in a second stage.

[0013] In a preferred embodiment, an additional flap or tab may be positioned adjacent to and connected to the flap. These may be smaller flaps that overlap adjacent plates to form overlapping joints, or they may form additional walls, either as an outer structure of the flame-resistant shield or as an internal separation wall for the flame-resistant shield to allow for further separation of battery units or ancillary equipment within a battery module or pack.

[0014] Preferably, plates or flaps, preferably along edges that contact other flaps, can further include notches, slots, or other design features to facilitate folding or connection between adjacent contacting plates or flaps. The flame-resistant shield blank can include other cutouts to facilitate covering or to serve as passages to allow equipment to reach battery cells, modules, or packs that are covered by the formed flame-resistant shield.

[0015] A preferred flame-resistant shielding blank comprises at least a main plate and at least four flaps arranged along portions of the main plate so that, when folded, the plate and flaps form a shape that conforms to the battery module or battery pack being covered.

[0016] In an alternative embodiment, the flame resistant shield may comprise one or more flame resistant shield blanks, whereby portions of the main plate or flaps can be folded to form interior walls or dividers within the ultimately formed flame resistant shield.

[0017] Most folds that are formed result in an internal angle between two faces of adjacent plates or flaps of between 60° and 120°, preferably close to 90°.

[0018] The flame-resistant shielding blank of the present invention may further include at least partial coverage of at least one surface with a flexible flame-resistant layer, preferably at least one of a flexible tape, sealant, film, or foil. This at least partial coverage is preferably at least the side areas of the fold lines with the flexible flame-resistant layer, preferably a tape, sealant, film, or foil, so that when the shielding blank is folded into its final shape and the bridge element is at least partially broken or deformed, the flexible layer provides a connection between the main plate and the at least one flap. The flexible layer may be flexible during folding and may be cured with a hard adhesive after forming the final flame-resistant shielding configuration. This curing may be accelerated by heat treatment, UV treatment, or application of pressure to the area or the entire area.

[0019] The flame-resistant shielding blank is made of a single material blank with at least one flame-resistant layer, which may be composed of a composite material including reinforcing fibers or filaments, preferably a fibrous material such as a nonwoven or woven fabric, impregnated with a matrix material selected from at least one of polyurethane, polyisocyanurate, epoxy, or silicone, the composite material having flame resistance up to at least 1100°C, and the matrix material impregnating the fibrous material so that the flame-resistant layer is airtight.

[0020] Preferably, flame resistance is further optimized by ensuring that all fiber material is covered and that no fiber ends protrude from the face of the flame resistant shielding blank facing a potential ignition source such as a battery cell. Preferably, an additional coating, preferably of the same matrix material or a similar material, is applied over the flame resistant shielding blank.

[0021] In a preferred embodiment, the fibers or filaments used, for example in the form of a nonwoven fabric, are bonded with a thermosetting binder before being impregnated with a final matrix material, such as polyurethane. Preferably, a water-based acrylic binder is used in the preliminary bonding step.

[0022] The thickness of the flame resistant layer may be comprised between 0.5 mm and 7 mm, preferably between 0.5 mm and 5 mm, more preferably between 0.7 mm and 3 mm.

[0023] The density of the flame-resistant layer is 800 kg / m 3 and 2500 kg / m 3 Between 1000 kg / m and 2000 kg / m, preferably 3 and 1800 kg / m 3 It may include between.

[0024] The weight of the fibrous material in the flame resistant layer may be between 40% and 80%, preferably between 50% and 70%, of the total weight of the flame resistant layer. The flame resistant layer may comprise multiple layers that together form the flame resistant layer, including, for example, organo sheet or unidirectional tape, to further enhance the impact performance of the sheet.

[0025] In an alternative embodiment, the material blank for the flame-resistant shield blank is a mica-based material, for example, the rigid flame-resistant layer can include mica platelets forming a plate-like structure and a binder, such that the rigid flame-resistant layer has flame resistance up to at least 1100°C.

[0026] In an alternative embodiment, the flame-resistant shielding blank is covered with an additional flame-resistant layer on at least one side of the blank, over the front plate surface, including the cut areas with the bridge elements according to the present invention. When the flame-resistant shielding blank is folded into its final form, the bridges break or deform to allow folding, while the film conforms to the new shape to close and seal the folded structure. The applied seal or foil can be cut partially larger than the flame-resistant shielding blank to form an overlap area that can be used to seal and close the newly formed corner where the edges of adjacent flaps meet during folding and forming of the final structure.

[0027] The fibrous material may include fibers and / or endless filaments.

[0028] The fibers or filaments may be at least one of ceramic fibers, glass fibers, carbon fibers, mineral-based fibers, and oxidized polyacrylonitrile fibers.

[0029] When staple fibers are used, the average length for at least 80% of the fibers is preferably comprised between 20 mm and 150 mm, more preferably between 30 mm and 80 mm, and even more preferably between 40 mm and 60 mm.

[0030] The fibrous material may comprise fibers bonded with a thermosetting binder prior to impregnation with the matrix material, preferably the pre-bonding is performed with a thermosetting binder.

[0031] Polyurethane or polyisocyanurate can preferably be used as a possible matrix, and / or a pre-binder can preferably be obtained from the reaction of a polyurethane- or polyisocyanurate-forming mixture without any blowing agent. The polyurethane or polyisocyanurate can be applied as an in-mold reaction mixture to impregnate the fibrous material and form the flame-resistant shield blank in a one-step process. Preferably, the mold used can incorporate the final shape and allow for in-mold cutting of the fold lines and / or contours of the flame-resistant shield, leaving the bridge elements uncut.

[0032] The pre-bond material and the matrix material may further include a flame retardant or additive.

[0033] Optionally, a mica layer may be disposed between the at least two fiber layers prior to impregnation with the matrix material. The mica improves the flame resistant properties of the rigid flame resistant layer.

[0034] The method for producing a flame-resistant shielding blank according to the present invention comprises at least the following steps: - providing a textile material, wherein the fibers and / or filaments comprised in the textile material are preferably in the form of a woven, nonwoven or fabric; - dispersing the matrix-forming mixture in a fibrous material; - heat-compressing the stack thus formed, so that the matrix impregnates the fibrous material and completely envelops the fibres and / or filaments, so that most of the air bubbles can be forced out of the layer, forming an impermeable, rigid flame-resistant layer having a flame resistance up to at least 1100°C; - cutting the rigid flame-resistant layer thus formed into flame-resistant shielding blanks comprising a plurality of plates including at least one plate forming a panel and at least one plate forming a flap, and cutting additional fold lines between the plates and adjacent flaps while leaving the bridge elements uncut so as to maintain the integrity of the flame-resistant shielding blank formed.

[0035] The method may further include applying tape, film, sealant, or foil to at least one surface of the flame-resistant shielding blank at least above and beside the fold line, including the bridge element, so that, at least upon folding, adjacent plates are still connected by the tape, sealant, film, or foil after breaking and / or deforming the bridge element. This step may be applied before or after cutting the flame-resistant shielding blank, preferably after the cutting step to prevent any damage to the foil. A second cutting step may also be included to cut any unnecessary tape, foil, film, or sealant. Alternatively, the flexible flame-resistant coating may be applied before or after cutting the flame-resistant shielding blank.

[0036] A possible example of a flame resistant tape or foil could be a mica paper material combined with an organic and / or inorganic film, preferably a mica paper, forming the outer layer.

[0037] The method of folding a flame-resistant shielding blank of the present invention includes folding the flame-resistant shielding blank into a final shape of the flame-resistant shielding blank and using a flame-resistant adhesive to seal any gaps between plates that are in contact with each other after folding, the final shape representing a box shape having at least one open side, which box shape can be placed or slid onto a battery unit, cell, module, or pack, or any other unit requiring strict flame protection.

[0038] After the flame-resistant shield blank is folded into its final shape, additional sealant can be applied to fill any remaining gaps between the plates, preferably at least on any side facing the battery pack or module to be covered.

[0039] Producing the flame-resistant shield in a two-step process allows the possibility of storing and shipping the flame-resistant shield blank in a flat-pack state, and the placement of the bridge elements allows the flame-resistant shield to maintain its integrity and optimize material utilization depending on the shape design and the flame-resistant shield blank, while also allowing multiple designs to be formed from one flame-resistant shield blank by folding or combining different blanks.

[0040] Impregnation of the fibrous layer or layers can be carried out, for example, by a spray or flow process before entering the compression step in a continuous belt press or mold. Alternatively, a matrix material can be applied to the reinforcing fibrous material inside the mold just before or when the mold is fully closed. The binder or matrix element can be composed of any thermosetting polymer, including polyurethane, polyisocyanurate, epoxy, phenolic, or acrylic resins. Generally, thermosetting polymers are preferred due to their liquid state before curing, although thermoplastic polymers are also contemplated. Compression of the material thus impregnated is preferred to push out any air and obtain an airtight layer.

[0041] The use of an airtight flame resistant layer increases the overall flame resistance. [Brief explanation of the drawings]

[0042] [Figure 1A] FIG. 1A is an example of a flame-resistant shield blank and a flame-resistant shield according to the present invention. [Figure 1B] FIG. 1B is an example of a flame-resistant shield blank and a flame-resistant shield according to the present invention. [Figure 2A]FIG. 2A is an example of an alternative embodiment of a corner joint of a flame-resistant shield. [Figure 2B] FIG. 2B is an example of an alternative embodiment of a corner joint of the flame-resistant shield. [Figure 3] FIG. 3 is an example of a flame-resistant shield according to the present invention applied to a traction battery for an electric vehicle. DETAILED DESCRIPTION OF THE INVENTION

[0043] 1A shows an example of a flame-resistant shielding blank 1 according to the present invention, having a main panel 2 and flaps 3a, 3b, and 3c. The entire blank is cut from the same blank of material, whereby the main panel and adjacent flaps have cut lines that form the fold lines. However, at least in the unfolded blank, the main panel and adjacent flaps are connected to each other by at least one bridge element 4. These bridge elements are formed by the areas at the fold lines that have not yet been cut.

[0044] Although the material used for the flame-resistant shielding blank is a rigid flame-resistant composite, it is possible to break or fold small areas between the plates. Furthermore, the ends of the bridge elements that are broken or fold are not capable of puncturing or damaging surrounding areas or materials. Depending on the size of the flaps, the bridge elements may be wider or smaller. In relatively large flaps, there may be multiple bridge elements per side. The size of the bridge elements should be selected so that they are strong enough to hold together during transportation of the flame-resistant shielding blank, while breaking or folding the elements can be done without requiring a great deal of force when folding the flame-resistant shielding blank into its final shape.

[0045] Additionally, the size of the bridge elements should be selected so that they are strong enough to remain rigid during gripping and transportation by the robotic gripper elements during packaging, unpacking, and assembly.

[0046] The use of a substantially flat flame-resistant shield blank during production and logistics has the advantage of being relatively economical and environmentally friendly to transport, since there is less "air" or volume per part, compared to fully formed boxes that are shipped or stored for the same reasons. Furthermore, the box can be more easily adapted to the amount of surface area used when forming and placing the flame-resistant shield within a battery box. The flame-resistant shield thus formed can be placed on a battery module, cell, or pack. The shape can be adapted and the design for the blank can be created as needed. While a square box is shown, this may be the preferred solution for most current battery modules or packs. Also, other shapes can be formed in a substantially flat configuration that can be folded into a final structure according to the teachings of the present disclosure.

[0047] FIG. 1B shows the same configuration as FIG. 1A, but for clarity, the numbering has been omitted in favor of the folding scheme.

[0048] The produced flame-resistant shield blank can be formed into its final shape by folding it at fold line 5 in FIG. 1A as indicated by arrow f. For example, the fold is performed so that the edges of adjacent flaps abut one another, e.g., so that edges a and a' of adjacent flaps 3c and 3b abut one another. The newly formed shape can be further stabilized with adhesive beads or strips of sealing tape along the newly formed corners. The adhesive or sealing tape used should be flame-resistant to seal the box at the fold line. In the example of FIGS. 1A and 1B, the use of sealing strips on the inside is indicated by dotted lines on both sides of the fold line. Sealing strips or tape are used at least on the inside of the formed shape, but can be used on both sides of the fold line without interfering with folding the flame-resistant shield into its final shape. Preferably, a tape is used that is flexible to form the fold and has slight stretch to obtain proper sealing around the corners of the folded structure.

[0049] 2 shows an alternative embodiment for the connection of two adjacent flaps during folding, where the flaps may include an additional dovetail joint. Preferably, the bridge element is arranged in the dovetail joint, and the height t of the joint area is slightly greater than the thickness of the material, so that the folded or broken edge of the bridge and the thickness of the opposing flap form a substantially flat surface.

[0050] 3 shows a battery box 10 having a lower tray 12 and a lid 11. Disposed within the box are battery cells or modules 13 that may each be covered with a folded flame-resistant shield according to the present invention. Alternatively, the flame-resistant shield blank incorporates a design that, upon folding, includes additional connecting walls between modules, as shown by flame-resistant shield 1b.

[0051] To achieve a more attractive design, additional adjacent flaps may be used. This may also be a smaller flap that may overlap when other flaps are folded to obtain a more stable closure of the corners or fold lines. Such overlapping flaps may be dedicated to adhesive and sealing of the overlap area, for example, may already have adhesive applied to the flame-resistant shield blank that is later accelerated during folding to the final shape by heat, pressure, or UV curing.

[0052] An additional adhesive layer may be applied to the edges to connect the flame-resistant shield thus formed to the unit to be covered.

Claims

1. A flame-resistant shielding blank for covering multiple sides of a battery pack or battery module, comprising: a main plate and at least one flap cut from the same blank of material; the main plate and the at least one flap are adjacently connected to one another; and the connection comprises at least one bridge element that at least partially breaks or deforms when the flame-resistant shielding blank is folded into its final shape; Flame-resistant shield blank.

2. 2. The flame-resistant shielding blank according to claim 1, wherein each flap is separated from the main plate by at least a partial cut through the material blank, leaving a bridge element in the material blank as a connecting element.

3. 3. A flame-resistant shielding blank according to claim 1 or 2, wherein the material blank is provided with at least one hard layer, preferably a flame-resistant layer.

4. The material blank is provided with at least one rigid flame-resistant layer comprising at least one reinforcing fiber material, preferably at least one rigid flame-resistant layer comprising a woven and / or nonwoven fabric impregnated with a matrix material, whereby the rigid flame-resistant layer has flame resistance up to at least 1100°C. A flame-resistant shielding blank according to any one of claims 1 to 3.

5. The material blank has at least one rigid flame-resistant layer comprising mica platelets forming a plate-like structure and a thermosetting binder, whereby the rigid flame-resistant layer has flame resistance up to at least 1100°C. A flame-resistant shielding blank according to any one of claims 1 to 3.

6. 6. The flame-resistant shielding blank according to claim 1, further comprising at least partial covering of at least one side of the fold line with a flexible flame-resistant layer, preferably a tape, film, or foil, whereby when the shielding blank is folded into its final shape and the bridge element is at least partially broken or deformed, the flexible layer provides the connection between the main plate and the at least one flap.

7. 7. A flame-resistant shielding blank according to claim 1, comprising at least one flame-resistant layer made of a woven fabric and / or nonwoven fabric containing fibers impregnated with at least one of polyurethane, polyisocyanurate, epoxy, or silicone, wherein the polyurethane impregnates the porous fibrous nonwoven fabric so that the flame-resistant layer is impermeable to airflow and has flame resistance up to at least 1100°C.

8. The density of the flame-resistant layer is 800 kg / m ３ and 2500 kg / m ３ and more preferably between 1000 kg / m ３ and 1800 kg / m ３ The flame-resistant shielding blank according to any one of claims 1 to 7, which is included between

9. A flame-resistant shielding blank according to any one of claims 1 to 8, wherein the weight of the fibrous nonwoven or woven fabric is between 40% and 80%, preferably between 50% and 70%, of the total weight of the flame-resistant layer.

10. A flame-resistant shielding blank according to any one of claims 1 to 9, wherein the fibrous material comprises fibers that are bonded by a thermosetting binder before being impregnated with a matrix material, preferably polyurethane or polyisocyanurate, and preferably the thermosetting binder is an epoxy or phenolic binder.

11. A flame-resistant shielding blank according to any one of claims 1 to 10, wherein the fibers of the fibrous material include at least one of ceramic fibers, glass fibers, carbon fibers, mineral-based fibers, and oxidized polyacrylonitrile fibers.

12. A method for producing the flame-resistant shielding blank according to any one of claims 1 to 11, comprising at least the following steps: - providing a textile material, preferably in the form of a woven, nonwoven or fabric, wherein the fibers and / or filaments contained in said textile material have a flame resistance up to at least 1100°C; - dispersing a matrix-forming mixture in said fibrous material; - heat-compressing the stack thus formed, so that the matrix impregnates the fibrous material and completely envelops the fibres and / or filaments, forcing most of the air bubbles out of the layer, forming an impermeable, rigid, flame-resistant layer; - Cutting the rigid flame-resistant layer thus formed into a flame-resistant shielding blank having a main panel and at least one flap, wherein an additional fold line is cut between the main panel and the adjacent flap, leaving the bridge element uncut so as to maintain the integrity of the flame-resistant shielding blank formed.

13. 13. The method of claim 12, further comprising applying tape, film, sealant, or foil to at least one side of the flame-resistant shielding blank at least above and beside the fold line including the bridge element, whereby adjacent plates remain connected by the tape, sealant, film, or foil, at least after breaking and / or deforming the bridge element upon folding.

14. A method for folding a flame-resistant shielding blank according to any one of claims 1 to 11 or a flame-resistant shielding blank produced by the method according to claim 12 or 13, comprising: folding the flame-resistant shield blank into its final shape and using a flame-resistant adhesive to seal any gaps between the plates that are in contact with each other after folding; the final shape represents a box shape with at least one open side, so that it can be placed or slid onto a battery unit, cell, module or pack; method.

15. 15. The method of claim 14, wherein after the flame-resistant shielding blank is folded into the final shape, additional sealant is applied to fill any remaining gaps between plates on at least one surface, preferably at least on any surface facing the battery pack or module to be covered.

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