Battery cell and method

Abstract

The present disclosure relates to a battery unit (100) for an electric vehicle. The battery cell (100) comprises a battery tray (1) made of a composite material and defining an interior space configured for accommodating a battery (2) comprising one or more battery cells. The inner space is delimited by a bottom wall (3) and one or more side walls (4). Furthermore, the side wall (4) comprises a side flange (5) extending outwardly from the side wall (4), and the side flange (5) comprises one or more embedded metal inserts (6). The metal insert (6) is configured for receiving one or more fasteners in order to secure the battery tray (1) to a load bearing structure of an electric vehicle. The present disclosure further relates to a method (500) for manufacturing a battery cell.

Description

[0001] This application claims the benefit of European Patent Application No. EP22382911.0 filed on September 30, 2022. The present disclosure relates to battery cells for vehicles. More specifically, the present disclosure relates to battery cells including battery trays made of composite materials. The present disclosure further relates to methods for manufacturing such battery cells. Background Art

[0002] Vehicles such as cars incorporate a structural frame designed to withstand all loads that the vehicle may be subjected to during its life. The structural frame or "body in white" (BIW) is also designed to withstand and absorb impacts in the event of, for example, a collision with another car. The structural frame is also designed to be as light as possible in order to reduce, for example, CO 2 The emission of pollutants such as chlorine to the environment or the reduction of electricity consumption in electric vehicles.

[0003] The structural framework or BIW of an automobile may include, for example, bumpers, pillars (e.g., A-pillars, B-pillars, C-pillars), side impact beams, and body fenders. These and other structural members may have one or more regions with a generally U-shaped (also referred to as a "hat" shaped) cross-section. These structural members may be manufactured in a variety of ways and may be made from a variety of materials. For example, body fenders may be made from steel, particularly ultra-high strength steel (UHSS), and may be manufactured by press hardening.

[0004] Ultra-high strength steel (UHSS) exhibits optimized maximum strength per unit weight and favorable formability for the structural frame of a vehicle or at least its components in the automotive industry. In the present disclosure, UHSS may be considered to be a steel having a maximum tensile strength (after hot stamping) of at least 1000 MPa, preferably at most about 1500 MPa or at most 2000 MPa or more. An example of UHSS used in the automotive industry is 22MnB5 steel.

[0005] Machining components for vehicles may include forming metal sheets, in particular steel sheets, so as to give the sheets a desired shape. One method used in particular in the automotive industry is hot forming die quenching (HFDQ). In the HFDQ method, a steel blank is heated to above the austenitizing temperature, above Ac1 or above Ac3. After heating above the austenitizing temperature, the blank is placed in a hot forming press. The blank is deformed and simultaneously quenched (cooled rapidly). Cooling is generally carried out at a rate above the so-called critical cooling rate.

[0006] The rapid development of electric vehicles (EVs) and hybrid vehicles has forced the industry to design new vehicle components, for example, for weight reduction to achieve improved vehicle range, and for housing and protecting new vehicle components, etc. Structural components with new geometries and alternative materials are being manufactured and integrated into EVs to achieve safety and weight reduction goals.

[0007] The traction battery is an essential part of EV and hybrid vehicles that provides power to the vehicle's electric motor. The electronic and chemical properties of these batteries make them particularly sensitive to high mechanical loads, such as crash impacts. In order to extend the battery life and protect them from external impacts, the automotive industry has put considerable effort into providing battery housings and load-bearing structures suitable for EVs. Therefore, over the past few years, a wide range of protective elements have been designed and engineered to house and protect traction batteries.

[0008] Steel battery boxes or battery trays have been designed for this purpose. Polymer (plastic) or composite components have also been developed. Although plastics and composites can be lighter than metal components, they need to be designed and sized to protect against severe impacts.

[0009] An object of the present disclosure is to provide improvements in structures for protecting automotive batteries. Summary of the invention

[0010] In a first aspect, a battery unit for a vehicle is provided. The battery unit includes a battery tray made of a composite material. The battery tray defines an interior space that is configured to accommodate a battery including one or more battery cells. The interior space of the battery tray is bounded by a bottom wall and one or more side walls. In addition, the lateral walls include side flanges extending outwardly from the lateral walls. In addition, the side flanges include one or more metal inserts embedded in the side flanges. The metal inserts are configured to accommodate one or more fasteners to secure the battery tray to a load-bearing structure of an electric vehicle.

[0011] The composite battery tray provides a lightweight structure for the disclosed battery cell. Furthermore, the composite material can be selected to provide tailored mechanical strength, for example, the composite material can provide higher strength in one direction than in another direction. Additionally, the introduction of metal inserts embedded in the side flanges of the battery tray provides a secure connection point between the battery tray and other structures of the electric vehicle, such as a load-bearing frame surrounding the battery tray or (additional) parts of the vehicle frame. Thus, the provided battery cell has the benefits of lightness from a unit made of a composite or polymer material, while at the same time it provides a secure connection between the components, which allows mechanical loads to be transferred through the load-bearing structure.

[0012] Throughout this disclosure, an “electric vehicle” or “hybrid vehicle” may be understood to include any vehicle having a battery that is at least partially configured to provide power to an electric drivetrain of the vehicle.

[0013] Furthermore, throughout this disclosure, references to "mechanical properties of a structure" may be understood to refer to the mechanical properties of the material from which the structure is formed. Thus, unless otherwise indicated, comparisons of mechanical properties of structures, components, or other parts refer to the material, not to the geometry or other characteristics of the material.

[0014] In an embodiment, the composite material used to form the battery tray may include glass fibers, although other materials such as carbon fibers or aramid fibers may also be used.

[0015] In some embodiments, the battery tray can be made of sheet molding compound. Sheet molding compound is a composite material provided in sheet form. The sheet is typically made by extending a resin paste into a surface on which chopped fibers are distributed. Another layer of resin is then added on top of the chopped fibers and compacted and stored while the sheet cures.

[0016] In an embodiment, the metal insert is a plate including at least two fastener holes. The fastener holes can be configured to receive fasteners and secure the battery tray to the load-bearing structure of the electric vehicle. Thus, the holes can act as connection points between the plate and the load-bearing structure and can limit the forces and torques experienced by the battery tray in the event of an impact.

[0017] In some embodiments, the metal insert may be perforated. The strength of the composite-metal sheet connection may be enhanced by the perforations, i.e., the composite material may at least partially flow into the perforations and solidify inside, thereby increasing the contact surface between the components and creating a solid bridge of composite material between the two sides of the metal sheet.

[0018] In an embodiment, the metal insert comprises at least one pin protruding perpendicularly from the surface of the side flange. The pin can serve as an additional contact point between the metal insert and other components of the battery cell, such as a fixing bracket. A pin is understood here to cover any structural element used to fasten objects together or as a support by which one object can be suspended from another object. The pin can be implemented here, for example, as a stud or a rod, or a bolt.

[0019] In an embodiment, the battery unit may further include a load-bearing frame. In addition, the load-bearing frame may include structural elements made of aluminum. These structural elements may be relatively light and may provide support and protection for the battery tray.

[0020] In some embodiments, the battery tray may further include a plurality of reinforcing ribs located at the bottom wall. In embodiments, the reinforcing ribs may define a substantially Cartesian grid. The ribs may increase the rigidity of the tray and may also promote air circulation between the bottom wall and the battery.

[0021] In an embodiment, the battery unit may further include one or more fixing brackets configured to couple with the metal insert and at least partially retain one or more of the battery cells in the internal space. The fixing bracket may thus be understood as a component of the battery unit that is configured to at least partially cover the internal space of the battery tray and limit the movement of the battery by geometric interference. The fixing bracket may also reduce vibration of the battery within the battery tray.

[0022] In some embodiments, the fixing bracket may include an internal channel configured to guide a cooling medium. In addition, the fixing bracket may include an aluminum profile extending into an interior space, and the internal channel may be located in the interior space. Therefore, the fixing bracket with a cooling channel may help keep the battery within a suitable temperature range.

[0023] In embodiments, the aluminum extrusion may be configured to be positioned adjacent to or between battery cells.

[0024] In some embodiments, the fixing bracket includes at least one fixing segment configured to receive a pin of a metal insert. The fixing segment can be substantially horizontal. Thus, the fixing bracket can be connected to the load-bearing structure via the metal insert. This configuration allows the load to be transferred from the load-bearing structure or frame to the fixing bracket without the composite battery tray having to withstand high mechanical loads.

[0025] Furthermore, in an embodiment, the fixing segments are configured to be connected together by an aluminum profile.Thus, the fixing bracket may have a fixing segment surrounding the periphery of the battery cell.

[0026] In some embodiments, the battery unit may include a central separator support configured to be positioned between rows of battery cells. The central separator may be configured to limit the movement of the battery by geometric interference and may include a plurality of internal channels to conduct a cooling medium for battery cooling.

[0027] In another aspect, a method for manufacturing a battery cell for an electric vehicle is provided. The method includes providing a plurality of metal inserts in a mold. In addition, the method includes providing a sheet molding compound in the mold. Then, the method includes forming the battery cell by thermal compression molding. Note that the first and second steps of the method can be performed in the order described above or in reverse order.

[0028] According to this aspect, the provided method allows the battery cell to be produced in a single forming step. This allows the integration of metal inserts into the composite material, which provides additional strength to the battery tray. In addition, the resulting battery cell is lighter than a similar battery cell primary made of metal, and it still provides sufficient rigidity to withstand the weight and other mechanical loads associated with the battery. In addition, the disclosed method allows the battery cell to be manufactured in a fast and inexpensive manner. In addition, the method allows the use of at least partially recycled composite materials, helping to reduce overall CO 2 emission.

[0029] In some embodiments of the method, forming the battery tray may include heating the mold between 100° C. and 160° C. Furthermore, the battery tray may be formed by applying a pressure between 30 and 120 bar to the sheet molding compound. Furthermore, the sheet molding compound may include glass fibers.

[0030] Throughout this disclosure, a rib may be understood as an elongated, substantially straight portion of a battery tray for local reinforcement. The rib may be manufactured during the process of forming the battery tray by thermal compression molding, or may be included in the battery tray after the battery tray has been manufactured. The rib may be made of a composite material, or may be made of any other material and embedded in the composite material during the process of forming the battery tray. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Non-limiting examples of the present disclosure will now be described with reference to the accompanying drawings, in which: Figure 1 schematically illustrates a perspective top view of one embodiment of a battery cell according to the present disclosure; Figure 2 Schematically shows Figure 1 A perspective top view of the battery tray in FIG. Figure 3 schematically illustrates a perspective top view of one embodiment of a metal insert; Figure 4 Schematically shows the Figure 1 A cross section of the width of the battery cell in ; and Figure 5 is a flow chart of a method for manufacturing a battery cell according to the present disclosure.

[0032] The drawings relate to example implementations and are intended only to aid in understanding the claimed subject matter and are not intended to limit the same in any sense. DETAILED DESCRIPTION

[0033] Figure 1 A battery cell 100 for a vehicle, in particular an electric vehicle or a hybrid vehicle, is schematically shown.

[0034] The battery unit 100 includes a battery tray 1 made of a composite material. The battery tray 1 defines an interior space, which is configured to accommodate a battery 2 including one or more battery cells. The interior space of the battery tray 1 is defined by a bottom wall 3 and at least one side wall 4. In addition, the side wall 4 includes a side flange 5 extending outward from the side wall 4. In addition, the side flange 5 includes one or more metal inserts 6 embedded in the side flange 5. In addition, the metal insert 6 is configured to accommodate one or more fasteners to fix the battery tray 1 to the load-bearing structure of the electric vehicle.

[0035] The provided battery tray 1 is made of a composite material and can therefore be relatively lightweight. In addition, the composite material can be selected and customized to provide specific mechanical properties for the battery tray 1. For example, the composite material may include a biaxial or triaxial fiber layer to increase the mechanical properties of the tray in a specific direction. In addition, the materials of the fibers and resins can also be selected to obtain a final product, i.e., a battery tray 1, having specific mechanical properties. For example, the fibers may include glass fibers, carbon fibers, or aramid fibers, etc. In some embodiments, different types of fibers may be combined in the same tray.

[0036] In addition, the metal insert 6 embedded in the side flange 5 of the battery tray 1 provides additional local strength to the battery tray 1. More specifically, the metal insert 6 can transfer the load acting on the battery unit 100 through a relatively high-strength component, thereby limiting the magnitude of the load acting on the composite battery tray 1. The metal insert 6 can be made of steel.

[0037] also, Figure 1 The embodiment of the battery unit 100 shown in FIG. 1 shows that the battery unit 100 may also include a carrying frame 8, which includes a structural element 81. The carrying frame 8 may substantially completely surround the battery tray. In this embodiment, the carrying frame 8 may include two longitudinal cross members connected to the two cross members.

[0038] The load-bearing frame 8 can provide additional protection for the battery tray (and the battery inside) to resist external impacts, such as side collisions. In addition, the structural element 81 can provide protection at a relatively low weight, for example, the structural element 81 can be an aluminum extrusion profile with a low average density.

[0039] Furthermore, the carrier frame 8 may also facilitate integration of the battery unit 100 in an EV. For example, the carrier frame 8 may include connection points to a body-in-white of an EV.

[0040] also, Figure 1The embodiment of the battery unit 100 in the embodiment includes a fixing bracket 7 configured to be coupled with the metal insert 6. The fixing bracket 7 is configured to hold one or more battery cells at least partially in the interior space of the battery tray 1. The fixing bracket 7 can be made of metal, such as stainless steel or aluminum.

[0041] In some embodiments, the fixing bracket 7 may include a fixing section 72 or a flange configured to receive the pin 62 of the metal plate 6 (this will be referred to as Figure 3 further explanation).

[0042] The fixing bracket 7 in the example shown comprises a substantially vertical portion 71 and a substantially horizontal flange or fixing section 72. The flange or fixing section 72 may extend inwardly to hold the battery cell.

[0043] In addition, if Figure 1 As shown, the fixing bracket 7, in particular the vertical portion 71, may include an internal channel 73 configured to guide a cooling medium. The cooling medium may be water and / or ethylene glycol or another suitable heat exchange liquid. The fixing bracket 7 may extend into the interior of the tray adjacent to a row of battery cells of the battery, i.e. between the side wall of the tray and the row of battery cells. These internal cooling channels may extend substantially parallel to each other in the longitudinal direction.

[0044] In an embodiment, the fixing bracket may be made by extrusion, such as aluminum extrusion. The extruded profile may incorporate cooling channels.

[0045] Furthermore, in some embodiments, the battery unit 100 may include a central separator bracket 74 configured to be located between rows of battery cells, ie, both sides of the separator bracket 74 may be adjacent to the battery cells.

[0046] Thus, in some embodiments, the battery unit 100 may include an aluminum profile 71 that at least partially surrounds the battery 2, and a central separator bracket 74 between the battery cells. In the illustrated embodiment, the battery unit 100 includes two rows of battery cells in the battery tray. The central separator bracket 74 may be arranged between the two parallel rows. In the illustrated embodiment, the central separator bracket 74 may include a horizontal portion or horizontal flange that helps to retain the battery cells.

[0047] It should be clear that in Figure 4 The vertical separation between the bracket 74 and the battery cells of the battery is shown in an exaggerated manner.

[0048] The center divider bracket 74 may include internal cooling passages in a manner similar to that described for the fixed bracket 7. Figure 4 The arrangement of the vertical portions or profiles 71 and the central divider support 74 relative to the battery cells can be seen in more detail in FIG.

[0049] Figure 2 yes Figure 1 Schematic diagram of a battery tray 1 of a battery cell 100. As previously described, the battery tray 1 defines an interior space bounded by a bottom wall 3 and at least one or more side walls 4. In this embodiment, the battery tray is rectangular and includes four side walls 4, but battery trays 1 having other geometric shapes may also be provided.

[0050] Figure 2 The battery tray 1 in the embodiment of the embodiment also shows that the side walls 4 include a side flange 5, in which one or more metal inserts 6 are embedded. In the embodiment shown, all four side walls 4 include side flanges 5, but in other embodiments, some of the side walls 4 may not include side flanges 5.

[0051] The composite battery tray 1 can be manufactured using compression molding or sheet molding compound. In this case, the sheet molding compound (SMC) can be cut into pieces of appropriate size and placed in a heated mold of a mold. In an embodiment, the heated die head can be at a temperature of 100-160°C. The mold (one or more) of the mold can then be put together and closed, applying a pressure of 30-120 bar. Thus, when the viscosity of the material decreases, the SMC flows and fills the mold cavity. Note that other techniques in which the pressure applied to the SMC is quite low, i.e., less than 30 bar, can also be used.

[0052] SMC made of fiberglass can cure between 30 seconds and 150 seconds after starting the forming process. Therefore, the entire manufacturing cycle can be as fast as 80 seconds, including the loading and unloading movements of the parts, allowing high-volume production at reduced material costs.

[0053] The composition of the SMC can be tailored to provide a composite material with improved properties. For example, other fibers can be introduced into the SMC to increase the strength- and stiffness-to-weight ratio. In addition, other additives can be provided to prevent surface microcracks caused by degassing.

[0054] Different types of thermosetting resins may be used, such as polyester resins, vinyl ester resins, epoxy resins, or poly(methyl methacrylate) (PMMA). Fiber reinforced composites can not only provide relatively lightweight structures, but if the right materials (and in particular the right resins) are used, they can also act as electrical insulation.

[0055] It should be noted that Figure 2The battery tray 1 in the embodiment further includes a plurality of reinforcing ribs 11 located at the bottom wall 3. The ribs 11 can provide rigidity to the bottom of the tray. The ribs 11 can be formed integrally with the battery tray 1. For example, a mold for manufacturing the battery tray can include a suitable geometry, and the ribs can be formed of a composite material.

[0056] In this embodiment, the stiffening ribs 11 define a generally Cartesian grid to provide stiffness in two perpendicular directions (eg, longitudinal and transverse directions).

[0057] The reinforcing ribs 11 can also provide a gap between the bottom wall and the battery 2, and thus they can enhance air flow circulation and battery cooling. In addition, the height of the reinforcing ribs 11 can be selected so that when the battery 2 is located on the reinforcing ribs 11, the battery 2 is substantially aligned with the side flanges 5.

[0058] In other embodiments, the composite battery tray 1 can be manufactured by hand layup, which includes manually placing layers of any dry fabric onto a tool (mold) to form a laminate stack. Resin can then be applied to the dry fabric, for example, by resin infusion or injection using resin transfer molding (RTM). In another example, prepregs (fabrics pre-impregnated with resin) can be used. After the prepregs are laid, they can be heated and cured.

[0059] In other cases, the manufacturing process may include laying down fabric that has been coated with resin and then debulking the stack. Debulking may be done by hand, by rollers, or using vacuum bagging techniques.

[0060] Figure 3 Schematically, a perspective top view of an embodiment of a metal insert 6 is shown. In this embodiment, the metal insert 6 is a plate comprising two fastening holes 61 in order to connect the metal insert 6 with other components of the battery cell 100 and more precisely with the battery cell 100. Figure 1 The supporting frame 8 shown in FIG.

[0061] The metal insert 6 shown in this embodiment defines a substantially triangular shape with two fastener holes 61 at the vertices of the longest sides and a pin 62 protruding perpendicularly from the surface of the metal insert 6. In other embodiments, the metal insert 6 may have fastener holes 61 and pins 62 distributed in different ways. For example, the metal insert 6 may have three fastening holes substantially located at the vertices of the triangle and the pin 62 located at a substantially central position. It should be noted that the pin 62 may be configured to protrude perpendicularly from the surface of the side flange 5 to engage with the fixing bracket 7 of the battery cell 100.

[0062] The pin 62 may be a simple rod, or in other embodiments may be configured as a stud or bolt, for example.

[0063] Likewise Figure 3 As shown, the metal plate can be a perforated plate. The perforations here can be understood as through holes, which can generally be smaller than the fastener holes. The bonding strength between the metal plate 6 and the battery tray 1 can be enhanced by the perforations 63, that is, the composite material of the battery tray 1 can at least partially flow into the perforations 63 and solidify inside, thereby increasing the contact surface between the components and creating a solid bridge of the composite material between the two sides of the metal plate. Therefore, the bonding can be not only chemical but also mechanical. In other embodiments, and also in order to strengthen the metal plate-battery tray connection, the metal plate 6 may include surface ridges or surface depressions.

[0064] Figure 5 is a flow chart of a method 500 for manufacturing a battery cell 100 according to the present disclosure.

[0065] The method 500 includes, at block 501, providing a plurality of metal inserts 6 in a mold. The method further includes, at block 502, providing a sheet molding compound in the mold. Furthermore, the method includes, at block 503, forming the battery tray 1 by thermocompression molding.

[0066] As previously described, the provided method 500 allows for a simple, fast, and reliable way to manufacture the battery cell 100. Furthermore, the method 500 can be easily automated for mass production, thereby reducing manual supervision and associated costs.

[0067] In an example, and as previously mentioned, forming the battery cell 100 may include heating the mold to between 100° C. and 160° C. and applying between 30 bar and 120 bar of pressure to the sheet molding compound. Additionally, the sheet molding compound may include glass fibers, which may result in a total manufacturing time of about 80 seconds.

[0068] Furthermore, the method 500 may be adapted to form a battery cell 100 having any combination of the technical features discussed above.

[0069] After the tray is manufactured, a plurality of battery cells can be introduced into the tray. In the example of the previous figures, two rows of battery cells are provided. Stop elements can be arranged at two opposite ends of the row of battery cells. The fixing brackets can be attached to the metal insert along at least two sides of the battery tray.

[0070] The fixing brackets may be mechanically connected, for example screwed, to the metal insert. The fixing brackets may also be connected to the retaining elements so that they at least partially cover the battery cells and thereby hold the battery cells in place. The central divider bracket may be arranged between the rows of battery cells and connected to the retaining elements at both ends.

[0071] Although only a plurality of examples are disclosed herein, other replacements, modifications, uses and / or their equivalents are possible. In addition, all possible combinations of the described examples are also contemplated. Therefore, the scope of the present disclosure should not be limited by the specific examples, but should only be determined by a reasonable reading of the appended claims.

Claims

1. A battery unit (100) for a vehicle, the battery unit (100) include: A battery tray (1) is made of a composite material and defines an interior space, the interior space is configured to accommodate a battery (2) including one or more battery cells, and the interior space is bounded by a bottom wall (3) and one or more side walls (4), wherein The side wall (4) comprises a side flange (5) extending outwardly from the side wall (4), and wherein the side flange (5) comprises one or more metal inserts (6) embedded in the side flange (5), and The battery unit further comprises a carrying frame (8), which substantially completely surrounds the battery tray (1), and wherein The metal insert (6) is configured to receive one or more fasteners for securing the battery tray (1) to the carrier frame (8).

2. The battery cell according to claim 1, in, The battery tray is made of sheet molding compound.

3. The battery cell according to any one of claims 1 and 2, in, The composite material includes glass fibers.

4. The battery cell according to any one of claims 1 to 3, in, The metal insert is a plate comprising at least two fastening holes (61).

5. The battery cell according to any one of claims 1 to 4, in, The metal insert is a porous plate.

6. The battery cell according to any one of claims 1 to 5, in, The metal insert includes at least one pin (62) protruding perpendicularly from the surface of the side flange.

7. The battery cell according to any one of claims 1 to 6, in, The load-bearing frame comprises structural elements (81) made of aluminium.

8. The battery cell according to any one of claims 1 to 7, in, The battery tray further comprises reinforcing ribs (11) at the bottom wall, the reinforcing ribs optionally defining a substantially Cartesian grid.

9. The battery cell according to any one of claims 1 to 8, in, The battery unit further includes one or more fixing brackets (7) configured to couple with the metal insert and to at least partially retain one or more of the battery cells in the interior space.

10. The battery cell according to claim 9, in, The fixing bracket includes a generally horizontal fixing section configured to receive a pin of the metal insert.

11. The battery cell according to claim 9 or 10, in, The fixing bracket further includes an internal passage (73) configured to guide a cooling medium.

12. The battery cell according to claim 11, in, The fixing bracket includes a substantially vertical portion, and the substantially vertical portion includes the internal passage (73) configured to conduct the cooling medium.

13. The battery unit according to any one of claims 1-12, further comprising a center separator bracket (74) configured to be positioned between two rows of battery cells.

14. A method (500) for manufacturing a battery cell for an electric vehicle according to any one of claims 1 to 13, the method include: providing (501) a plurality of metal inserts in a mold; providing (502) a sheet molding compound in the mold; as well as The battery cell is formed (503) by thermal compression molding.

15. The method according to claim 14, in, Forming the battery cell includes heating the mold to between 100° C. and 160° C. and applying a pressure between 30 bar and 120 bar to the sheet molding compound, and wherein the sheet molding compound includes glass fibers.

Images