Battery cell, battery cell stack and high-voltage battery

Abstract

The invention relates to a battery cell (10) for a high-voltage battery, in particular for use in an electric vehicle, having an interior space (12) and a housing (14), wherein the housing (14) encloses the interior space (12), and having at least one enveloping body (30), wherein the enveloping body (30) at least partially envelops an outer surface (15) of the housing (14). The enveloping body (30) is net-shaped or lattice-shaped with webs (37) and recesses (35) between the webs (37), wherein the webs (37) bear directly against the outer surface (15) of the housing (14) and the recesses (35) expose the outer surface (15) of the housing (14).

Description

[0001] The invention relates to a battery cell, a battery cell stack, a method for producing a battery stack and a high-voltage battery.

[0002] A directly cooled high-voltage battery (HV battery) is a type of battery used in electric vehicles and other applications such as boats, drones, and autonomous vehicles with high-voltage storage systems. In automotive engineering, the term "high-voltage" refers to alternating voltages in the range of 30 V to 1 kV (or direct voltages above 60 V to 1.5 kV). This voltage range is called "high voltage" because it is significantly higher than the usual on-board voltages in vehicles (usually 12 V) and places special demands on safety and technology.

[0003] In the production of high-voltage batteries, especially for use in electric vehicles, individual battery cells are assembled into a battery cell stack and then inserted into the high-voltage battery housing. Depending on its size and configuration, a high-voltage battery typically consists of several modules, which in turn are arranged in a master housing. This modular design allows for a certain degree of flexibility in the configuration and replacement of battery components.

[0004] Battery cells can be manufactured in a variety of shapes, including prismatic, cylindrical, and pouch cells. Each of these shapes has its own advantages and disadvantages and specific applications that depend on the requirements of the specific application. Prismatic cells are rectangular or cuboid-shaped and are often used in applications where space is limited, such as thin electronic devices and electric vehicles. Pouch cells are flat and flexible, similar to a bag. They are often used in applications where flexibility and the ability to conform to unusual shapes are important. Pouch cells are often found in thin, portable devices but can also be used in electric vehicles. Cylindrical cells have a cylindrical shape and are often used in electric vehicles, laptops, electronic devices, and other applications.

[0005] The choice of cell shape depends on various factors such as space requirements, heat dissipation, mechanical requirements, and application-specific requirements. Each cell shape has its own specific properties and advantages, and the decision for a particular shape depends on the specific requirements of the respective product.

[0006] The cylindrical shape, in particular, offers good heat dissipation and high mechanical stability. Cylindrical battery cells tend to be easier to cool because they have a larger surface area compared to other shapes. This is important for regulating the battery's temperature and extending its service life. Furthermore, cylindrical cells are often more robust and resistant to mechanical stress, especially under high pressure or shock. The main disadvantage of cylindrical battery cells is their space requirements. For applications with limited space, other cell shapes, such as prismatic or flat cells, may be more efficient. Furthermore, the production of cylindrical battery cells can be more expensive due to specific production processes and material requirements.

[0007] Cylindrical battery cells are therefore particularly suitable for applications where good cooling, high energy density, and robustness are essential, as is often the case with electric vehicles. In other applications where space or other form-factor requirements are critical, alternative cell shapes may be preferred.

[0008] The cooling system is one of the safety features of a high-voltage battery. The cooling system of a high-voltage battery is crucial for optimizing the battery's operating conditions, extending its service life, and ensuring its safety. High-voltage batteries can be cooled either actively or passively. With active cooling, a coolant is circulated using pumps to dissipate heat. The coolant is a special fluid designed to efficiently absorb and transfer heat. Typically, it is a mixture of water and antifreeze that is adjusted to the ambient temperature. However, batteries can also be oil-cooled, which use special cooling oils to absorb and dissipate heat from the battery cells. The cooling oil circulates through the cooling system, thus regulating the battery temperature.

[0009] EP 4 287 373 A1 discloses a battery cell whose housing is encased in an insulating material, wherein the outer peripheral surface of the insulating material is surrounded by a heat dissipation element. The heat dissipation element is a tubular element with both end portions open. The insulating material has a plurality of recesses.

[0010] The object of the invention is to create possibilities for further improving the cooling performance of a high-voltage battery, particularly for electric vehicles, in order to increase the performance, service life, and safety of the high-voltage battery. Furthermore, the manufacturing process of a high-voltage battery is to be further optimized.

[0011] This object is achieved according to the invention with respect to a battery cell by the features of patent claim 1, with respect to a battery cell stack by the features of patent claim 10, with respect to a method for producing a battery cell stack by the features of claim 11, and with respect to a high-voltage battery by the features of claim 12. The remaining patent claims relate to preferred embodiments of the invention.

[0012] The inventive net-like or lattice-like structure of the enveloping body with webs and recesses can improve the cooling of a high-voltage battery because the cooling medium has direct contact with the outer surface of the battery cell housing. At the same time, the inventive enveloping body achieves high mechanical stability and electrical insulation of the battery cell. Furthermore, the stability of a battery stack can be improved because the adhesive has direct contact with the housing in the region of the recesses of the enveloping body. Furthermore, the manufacturing process for enclosing a battery cell can be simplified because, in particular, an enveloping body designed as a net tube can be easily pulled over the housing of a battery cell. Furthermore, the net tube represents a further option for making the production of a high-voltage battery more sustainable due to the reduced plastic requirements.

[0013] According to a first aspect, the invention provides a battery cell for a high-voltage battery, in particular for use in an electric vehicle. The battery cell comprises an interior space and a housing, wherein the housing encloses the interior space, and at least one enveloping body, wherein the enveloping body at least partially envelops an outer surface of the housing. The enveloping body is net-shaped or grid-shaped with webs and recesses between the webs, wherein the webs bear directly against the outer surface of the housing and the recesses expose the outer surface of the housing.

[0014] In a further development, the battery cell is designed as a lithium-ion battery.

[0015] In an advantageous embodiment, the shape of the battery cell is cylindrical, prismatic or designed as a pouch cell.

[0016] In a further embodiment, the shape of the battery cell is cylindrical.

[0017] Advantageously, the casing body is made of a plastic material.

[0018] In a further development, it is provided that the enveloping body consists of a net tube with a plurality of meshes, wherein the meshes form the webs and the spaces between the meshes form the recesses of the enveloping body.

[0019] In particular, the mesh of the net hose is made of polyethylene.

[0020] Advantageously, the plastic material of the casing contains a flame retardant.

[0021] In particular, the casing provides electrical insulation for the battery cell.

[0022] According to a second aspect, the invention provides a battery cell stack for a high-voltage battery, in particular for use in an electric vehicle. The battery cell stack comprises a plurality of battery cells, wherein one battery cell is configured according to the first aspect.

[0023] According to a third aspect, the invention provides a method for producing a battery cell stack according to the second aspect. In the method, an adhesive is introduced into the recesses of the enveloping body to bond the battery cells together to form a battery cell stack, wherein the adhesive forms a direct bond with the outer surface of the battery cell housing.

[0024] According to a fourth aspect, the invention provides a high-voltage battery with at least one battery module housing, in particular for use in an electric vehicle. The high-voltage battery comprises battery cells according to the first aspect and / or battery cell stacks according to the second aspect, wherein the high-voltage battery is designed as a directly cooled battery with a cooling system, and wherein a coolant of the cooling system flows around the outer surface of the battery cell housing exposed by the recesses in the enveloping body.

[0025] The invention is explained in more detail below with reference to embodiments shown in the drawing.

[0026] It shows: Fig. 1 a schematic sectional view of two cylindrical battery cells of a high-voltage battery; Fig. 2a a schematic sectional view of two cylindrical battery cells for a high-voltage battery with a shrink tube as a covering according to the prior art; Fig. 2b a schematic external representation of two cylindrical battery cells for a high-voltage battery with a shrink tube as a casing according to the prior art; Fig. 3a a schematic sectional view of two cylindrical battery cells for a high-voltage battery with an enveloping body according to the invention; Fig. 3b a schematic external representation of two cylindrical battery cells for a high-voltage battery with an enveloping body according to the invention.

[0027] Additional features, aspects and advantages of the invention or embodiments thereof will become apparent from the detailed description taken in conjunction with the claims.

[0028] Fig. 1 shows a schematic sectional view of two cylindrical battery cells 10 of a high-voltage battery arranged side by side. The high-voltage battery is used in particular in an electric vehicle. A cylindrical battery cell 10 consists of a cathode and an anode, a separator for separating the cathode and anode, and an electrolyte. The electrolyte is a conductive liquid that enables the movement of ions between the anode and cathode. The interior 12 of the battery cell 10, containing the cathode, anode, separator, and electrolyte, is surrounded by a cylindrical housing 14. The housing 14 of a cylindrical battery cell 10 is generally made of metal, in particular aluminum. It serves to protect the internal components while also providing mechanical stability. In addition, seals protect the battery cell 10 from external influences and prevent the electrolyte from leaking out.

[0029] The battery cell 10 is, in particular, a lithium-ion cell. Lithium-ion cells use lithium ions for electron transport between the anode and cathode during the discharge and charge processes. This enables high energy density and efficient energy transfer. The anode of lithium-ion cells is often made of graphite, while the cathode can be made of various materials such as lithium cobalt(III) oxide (LiCoO2), lithium iron(III) phosphate (LiFePO4), or other lithium metal oxides. The separator in lithium-ion cells is often a porous material that enables ion transport between the anode and cathode. The separator is typically made of polymer films made of polyethylene or polypropylene. The electrolyte in lithium-ion cells is a lithium-containing solution that supports the movement of the ions. The choice of electrolyte can affect the performance and safety of the cell.

[0030] Lithium-ion cells can be recharged through a controlled charging process and generally exhibit good cycling stability, meaning they can undergo many charge and discharge cycles without significant loss of capacity. Lithium-ion cells have a high energy density, meaning they can store a large amount of energy in a relatively small and lightweight package. This makes them ideal for portable electronic devices and electric vehicles.

[0031] However, lithium-ion cells require effective thermal management to control the temperature during operation, as overheating can impair performance and pose a safety risk. Furthermore, lithium-ion cells are sensitive to mechanical damage or overcharging. For this reason, modern lithium-ion batteries incorporate safety mechanisms such as protection circuits and temperature sensors.

[0032] In many cases, lithium-ion cells are encased in an additional protective layer, often made of plastic, to protect them from mechanical stress. This protective layer can take the form of shrink tubing or another plastic covering.

[0033] Fig. 2a shows a schematic sectional view of two cylindrical battery cells 10 for a high-voltage battery with a shrink tube 20 as a casing according to the prior art. Fig. 2b shows a schematic external view of the two cylindrical battery cells from Fig. 2a.

[0034] The heat-shrink tubing 20 is a flexible plastic tube that contracts when heated. The heat-shrink tubing 20 serves to mechanically protect the battery cell 10 and provide electrical insulation. Heat-shrink tubing is made of various polymer materials that shrink when heated and tightly wrap around the underlying object. Heat-shrink tubing is manufactured from various materials, such as polyolefin, PVC (polyvinyl chloride), and other thermoplastic polymers.

[0035] The heat-shrink tubing 20 protects the battery cell 10 from external influences such as shocks, vibrations, and scratches. This is important to maintain the structural integrity of the battery cell 10 and prevent potential damage that could compromise safety. Furthermore, the heat-shrink tubing 20 acts as an insulator, ensuring that the battery cell 10 does not suffer an electrical short circuit due to direct contact with other objects. Furthermore, the heat-shrink tubing 20 can help prevent or slow thermal damage in the event of an internal problem such as overheating or damage. Furthermore, the heat-shrink tubing 20 provides a barrier against moisture and environmental influences that could affect the cell's internal components.The shrink tube 20 is therefore part of the safety mechanisms used in modern lithium-ion batteries to ensure their reliability and safety.

[0036] Encapsulation is also possible for prismatic battery cells, which can be equipped with an outer covering in the form of plastic film or other protective materials. Pouch cells, which are flat and flexible, typically have a flexible plastic wrapper as their outer covering. This wrapper protects the cell from external influences, insulates it, and allows for a certain degree of adaptability to different shapes. However, pouch cells can also be reinforced with additional protective layers to ensure their stability.

[0037] In addition, certain types of battery cells may have multiple layers of different materials to provide additional protection and functionality.

[0038] Fig. 3a shows a schematic sectional view of two cylindrical battery cells 10 for a high-voltage battery with a net-shaped or grid-shaped enveloping body 30 according to the invention. Fig. 3b shows a schematic external representation of the two cylindrical battery cells 10 with the net-shaped or grid-shaped enveloping body 30 according to the invention.

[0039] The enveloping body 30 is designed, in particular, as a mesh tube 32 that is placed around the outer surface 15 of the housing 14 of the battery cell 10. The mesh tube 32 consists of elastic, diamond-shaped meshes, so that, due to its high elasticity and adaptability, it can be easily pulled over the housing 14 of the battery cell 10. The meshes of the mesh tube 32 are made of plastic, in particular polyethylene.

[0040] Due to the plastic fabric, the mesh tube 32 is highly elastic and optimally adapts to the product shape of the housing 14 of the battery cell 10. Since mesh tubes 32 are commercially available in various material thicknesses, sizes, and diameters, as well as in various colors with very different expansion ranges from a few millimeters to several centimeters, a mesh tube 32 can be easily integrated into battery production. In particular, battery cells 10 of different sizes can be additionally identified by a different color.

[0041] Plastic mesh hoses 32 are robust and resistant to various chemicals and solvents. Flame retardants can also be incorporated into the plastic of the mesh hose 32 to reduce its flammability. To install the mesh hose 32 around the housing 14 of the battery cell 10, the mesh hose 32 is typically cut to the desired length from a mesh hose reel.

[0042] In a further embodiment, the enveloping body 30 can be made of a net-like or lattice-like material other than a mesh tube. For example, the material of the enveloping body can be applied directly to the outer surface 15 of the housing 14 of the battery cell 10 using a printing process. What is crucial is that not the entire outer surface 15 of the housing 14 is covered by the material of the enveloping body 30, but rather that recesses 35 are provided in the enveloping body 30, which extend to the outer surface 15 of the housing 14 and expose it, while the webs 37 of a net or lattice bear directly against the outer surface 15 of the housing 14 and thus protect the battery cell 10 from external influences.

[0043] Due to the net-like or grid-like structure of the enveloping body 30 in the form of a net, grid, or grid, the battery cell 10 is not completely enclosed as with a shrink tube, but rather the outer surface 15 of the housing 14 has direct access to the environment. This is a great advantage for a high-voltage battery with direct cooling, since the cooling medium has direct contact with the housing 14 of the battery cell 10 via the recesses 35 and can thus flow directly around the outer surface 15 of the housing 14, allowing the heat emitted by the battery cell 10 to be dissipated more quickly.

[0044] Furthermore, advantages arise in the production of a battery cell stack 10 that can be inserted into a module of a high-voltage battery. The battery cells 10 with the enveloping body 30 according to the invention can be better bonded to form a battery cell stack because an adhesive or bonding agent can be introduced into the recesses 35 and has direct contact with the outer surface 15 of the housing 14 of the battery cell 10, so that a direct connection is established between the adhesive and the outer surface 15 of the housing 14 in the region of the recesses 35. However, the housings 14 of two adjacent battery cells 10 cannot touch directly because the webs 37 of the enveloping body 30 form a distance between the housings 14. Both the spatial distance and the webs 37 of the enveloping body 30 provide electrical insulation between two adjacent battery cells 10.

[0045] In a mesh hose 32, the webs 37 are formed by the mesh of the mesh, and the recesses 35 are formed by the spaces between the meshes. The mesh of the mesh hose 32 can ensure the required mechanical stability and electrical insulation, so that a complete covering of the housing 14 of the battery cell 10 is not necessary. The spaces between the meshes are significantly larger compared to the material thickness of the mesh, so that a large part of the outer surface 15 of the housing 14 of the battery cells 10 is directly accessible and can be flowed around by a coolant when installed in a high-voltage battery. This can significantly improve the heat exchange between the battery cells 10 and the coolant.In addition, less plastic material is used for the mesh tube 32 than for a shrink tube or another complete plastic covering of the battery cell 10, so that sustainability criteria can be better taken into account in the design of a high-voltage battery.

[0046] In the Fig. 3a and Fig. 3b shows a cylindrical battery shape for the battery cell 10. However, within the scope of the present invention, it is also possible to use the net-shaped or lattice-shaped enveloping body 30 according to the invention for other battery shapes, such as prismatic battery cells or pouch cells.

[0047] The inventive net-like or lattice-like structure of the enveloping body 30 with webs 37 and recesses 35 can improve the cooling of a high-voltage battery because the cooling medium has direct contact with the outer surface 15 of the housing 14 of the battery cell 10. At the same time, the inventive enveloping body 30 achieves high mechanical stability and electrical insulation of the battery cell 10. Furthermore, the stability of a battery stack can be improved because the adhesive has direct contact with the housing 14 in the region of the recesses 35 of the enveloping body 30. Furthermore, the manufacturing process for enclosing a battery cell 10 can be simplified because, in particular, an enveloping body 30 designed as a mesh tube 32 can be easily pulled over the housing 14 of a battery cell 10.In addition, the mesh hose 32 represents another way to make the production of a high-voltage battery more sustainable due to the reduced plastic requirements. Reference symbol 10 battery cells 12 Interior 14 housings 15 Exterior area 20 shrink tubing 30 enveloping bodies 32 mesh hose 35 recess 37 jetty QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 4 287 373 A1

[0009]

Claims

[1] Battery cell (10) for a high-voltage battery, in particular for use in an electric vehicle, with an interior space (12) and a housing (14), wherein the housing (14) encloses the interior space (12), and with at least one enveloping body (30), wherein the enveloping body (30) at least partially envelops an outer surface (15) of the housing (14), characterized by that the enveloping body (30) is designed in a net-like or lattice-like manner with webs (37) and recesses (35) between the webs (37), wherein the webs (37) lie directly against the outer surface (15) of the housing (14) and the recesses (35) expose the outer surface (15) of the housing (14). [2] Battery cell (10) according to claim 1, wherein the battery cell (10) is designed as a lithium-ion battery. [3] Battery cell (10) according to claim 1 or 2, wherein the shape of the battery cell (10) is cylindrical, prismatic or as a pouch cell. [4] Battery cell (10) according to claim 3, wherein the shape of the battery cell (10) is cylindrical. [5] Battery cell (10) according to one of claims 1 to 4, wherein the enveloping body (30) consists of a plastic material. [6] Battery cell (10) according to one of claims 1 to 5, wherein the enveloping body (30) consists of a mesh tube (32) with a plurality of meshes, wherein the meshes form the webs (37) and the spaces between the meshes form the recesses (35) of the enveloping body (30). [7] Battery cell (10) according to claim 6, wherein the meshes of the mesh tube (32) are made of polyethylene. [8] Battery cell (10) according to one of claims 5 to 7, wherein the plastic material of the enveloping body (30) contains a flame retardant. [9] Battery cell (10) according to one of claims 1 to 8, wherein the enveloping body (30) forms an electrical insulation for the battery cell (10). [10] Battery cell stack for a high-voltage battery, in particular for use in an electric vehicle, comprising a plurality of battery cells (10), wherein a battery cell (10) is designed according to one of claims 1 to 9. [11] Method for producing a battery cell stack according to claim 10, wherein an adhesive is introduced into the recesses (35) of the enveloping body (30) in order to bond the battery cells (10) to form a battery cell stack, and wherein the adhesive forms a direct connection with the outer surface (15) of the housing (14) of the battery cell (10). [12] High-voltage battery with at least one battery module housing, in particular for use in an electric vehicle, wherein the high-voltage battery comprises battery cells (10) according to one of claims 1 to 9 and / or battery cell stacks according to claim 10, and wherein the high-voltage battery is designed as a directly cooled battery with a cooling system, wherein a coolant of the cooling system flows around the outer surface (15) of the housing (14) of the battery cells (10) exposed by the recesses (35) of the enveloping body (30).

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