Battery cell, battery system, electric vehicle, and energy storage system

Abstract

A battery cell, a battery system, an electric vehicle, and an energy storage system are provided. The battery cell comprises: a metal cell housing having a top side, a bottom side and a side wall, the metal cell housing having an exhaust gas outlet at the top side and / or the bottom side of the metal cell housing to allow an exhaust gas flow to exit from the metal cell housing to form an exhaust gas side of the battery cell; and a cell cover covering the top side, the bottom side, and the outer surface of the side wall of the metal cell case. The monomeric covering includes a composite material including a fibrous mat embedded in a matrix support material. The monolith cover has an exhaust opening at the exhaust side and aligned with the exhaust outlet to allow an exhaust flow through the monolith cover.

Description

Technical Field

[0001] Aspects of embodiments of the present disclosure relate to a battery system and a vehicle including the battery system. Background Art

[0002] In recent years, vehicles for transporting goods and people have been developed that use electricity as a power source. Such electric vehicles are cars that are driven by an electric motor using energy stored in a rechargeable battery. Electric vehicles may be powered solely by batteries, or may be hybrid vehicles powered by, for example, a gasoline generator. Furthermore, vehicles may include a combination of an electric motor and a conventional internal combustion engine.

[0003] Generally, an electric vehicle battery (EVB) or traction battery is a battery used to power the propulsion of a battery electric vehicle (BEV). Electric vehicle batteries differ from starting batteries, lighting batteries, and ignition batteries in that they are designed to output power for sustained periods of time.

[0004] A rechargeable (or secondary) battery differs from a primary battery in that it is designed to be repeatedly charged and discharged, whereas the latter is designed to provide an irreversible conversion of chemical energy into electrical energy. Low-capacity rechargeable batteries are used as power sources for small electronic devices such as mobile phones, notebook computers, and video cameras, while high-capacity rechargeable batteries are used as power sources for hybrid vehicles and the like.

[0005] Generally, a rechargeable (or secondary) battery cell comprises an electrode assembly, a shell containing the electrode assembly, and an electrode terminal electrically connected to the electrode assembly, the electrode assembly comprising a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. An electrolyte solution is injected into the shell to enable the battery cell to be charged and discharged by an electrochemical reaction between the positive electrode, the negative electrode, and the electrolyte solution. The shape of the shell (such as a cylindrical or rectangular shape) can be selected based on the intended use of the battery. Lithium-ion (and similar lithium polymer) batteries, which are widely known for their use in laptop computers and consumer electronics, are the main form of secondary batteries for newly developed electric vehicles.

[0006] Rechargeable batteries can be used as a battery module including a plurality of unit battery cells connected in series and / or in parallel to each other to provide high power density, such as for electric motor drive of hybrid vehicles. For example, depending on the desired amount of electricity and in order to provide a high-power rechargeable battery, a battery module can be formed by interconnecting electrode terminals of the plurality of unit battery cells.

[0007] The battery module can be constructed in a block design or a modular design. In the block design, each battery is connected to a common current collector structure and a common battery management system, and its cells are arranged in a housing. In the modular design, multiple battery cells are connected together to form a sub-module, and several sub-modules are connected together to form a battery module. In automotive applications, the battery system typically includes multiple battery modules connected together in series to provide the desired voltage. The battery module may include a sub-module comprising a plurality of stacked battery cells (e.g., a battery stack or stack), each stack including cells connected together in parallel and then in series (XpYs) or cells connected together in series and then in parallel (XsYp).

[0008] A battery pack is a group of any number of (usually, identical) battery modules. The battery modules can be connected in series, parallel, or a series / parallel connection configuration to provide a desired voltage, capacity, and / or power density. The components of a battery pack include the individual battery modules and the interconnects that provide electrical conductivity between the battery modules.

[0009] In order to provide thermal control of the battery pack, a thermal management system may be employed to safely use the battery module by effectively dissipating, releasing and / or dissipating the heat generated from the rechargeable batteries therein. If the heat dissipation / release / dissipation is not adequately performed, temperature deviations may occur between the individual battery cells, and the battery module may not generate the desired amount of electricity. In addition, an increase in the internal temperature of the battery cell may cause an abnormal reaction therein, and therefore, the charging and discharging performance of the rechargeable battery may deteriorate, and the life of the rechargeable battery may be shortened. Therefore, cell cooling that effectively dissipates / releases / dissipates heat from the battery cell is desired.

[0010] The exothermic decomposition of a single component may lead to so-called thermal runaway. Generally, thermal runaway describes or refers to a process that is accelerated by a temperature increase and releases energy that further increases the temperature. Thermal runaway occurs when the temperature increase changes the conditions leading to a further increase in temperature, which usually leads to destructive consequences.

[0011] In rechargeable battery systems, thermal runaway is associated with strong exothermic reactions that are accelerated by temperature rise. These exothermic reactions include the combustion of combustible gas components within the battery pack housing. For example, when the monomer is heated above a critical temperature (usually above about 150°C), the battery cell may turn into thermal runaway. The initial heating may be caused by local faults, such as internal short circuits of the battery cell, heating from defective electrical contacts, short circuits with adjacent battery cells, etc. During thermal runaway, the failed battery cell (i.e., a battery cell that has or is experiencing a local fault) may reach a temperature of more than about 700°C. In addition, a large amount of hot gas is ejected from the inside of the failed battery cell through the exhaust opening in the monomer housing into the battery pack. The main components of the exhaust gas are H2, CO2, CO, electrolyte vapor and other hydrocarbons. Therefore, the exhaust gas is flammable and may be toxic. The exhaust gas also causes the gas pressure inside the battery pack to increase.

[0012] The battery cells in the battery system may be insulated with a plastic sheet that provides electrical insulation from the side walls and bottom of the battery housing within normal operating temperatures of up to about 150°C. The battery cells are pressed or glued into the cell compartment of the battery housing toward the bottom and side walls, while the top side (or upper side or upper end) of the battery cells is generally uncovered. During the temperature increase of the damaged battery cell caused by, for example, thermal runaway inside the battery cell, the plastic sheet may melt, resulting in a loss of electrical insulation. This may result in low resistance between components or assemblies with high differential voltages (e.g., at least about 20V), resulting in internal short circuits and / or arc discharges between these components / assemblies. For example, the housing of the battery cell, which is typically composed of aluminum, may be conductive at such voltages that internal short circuits and / or arc discharges may occur with adjacent battery cells due to the loss of electrical insulation between the battery cells. Summary of the invention

[0013] According to embodiments of the present disclosure, at least some of the disadvantages of the prior art are overcome by providing a battery cell that more safely handles thermal runaway by preventing short circuits and / or arc discharges.

[0014] The present disclosure is defined by the appended claims and their equivalents. The following description is limited thereto. Any disclosure outside the scope of the claims is for illustration and comparison purposes only.

[0015] According to one embodiment of the present disclosure, a battery cell includes: a metal cell shell having a top side, a bottom side and a side wall, the metal cell shell having an exhaust outlet at the top side and / or the bottom side of the metal cell shell to allow exhaust gas flow to leave the metal cell shell, thereby forming an exhaust side of the battery cell; and a cell cover covering the outer surface of the top side, the bottom side and the side wall of the metal cell shell. The cell cover includes a composite material, which includes a fiber mat embedded in a matrix support material. The cell cover has an exhaust opening aligned with the exhaust outlet at the exhaust side to allow exhaust gas flow to pass through the cell cover.

[0016] The battery cell may further include an electrode terminal disposed at a top side of the battery cell. The cell cover may have an opening through which the electrode terminal extends.

[0017] The fiber mat may include glass fibers, basalt fibers, and / or mica fibers.

[0018] The matrix support material may include a resin and / or a glue.

[0019] The matrix support material may include epoxy and / or polyurethane adhesives.

[0020] The monomer cover may also include a flame retardant.

[0021] The composite material may be a FR-4 composite material.

[0022] The cell cover may conform to the contours of the outer surfaces of the top side, bottom side, and side walls of the metal cell housing.

[0023] According to another embodiment of the present disclosure, a battery system includes a battery housing accommodating a plurality of battery cells as described above. The battery cells may be arranged to form one or more battery packs and / or battery modules.

[0024] According to another embodiment of the present disclosure, an electric vehicle includes the above-mentioned battery system.

[0025] According to another embodiment of the present disclosure, an electric vehicle includes the above-mentioned battery cell.

[0026] According to another embodiment of the present disclosure, an energy storage system (ESS) includes the above-mentioned battery system.

[0027] Further aspects and features of the present disclosure can be acquired from the dependent claims, the following description or from the practice of the described embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Aspects and features of the present disclosure will become apparent to those skilled in the art by describing in detail embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0029] Figure 1 is a schematic cross-sectional view of a battery cell according to an embodiment.

[0030] Figure 2 yes Figure 1 A schematic top view of a battery cell is shown.

[0031] Figure 3 is a schematic cross-sectional view of a battery cell according to another embodiment.

[0032] Some reference signs

[0033] 10 Battery Cell 10' Battery Cell

[0034] 12 Monolithic housing 12a Top side

[0035] 12b bottom side 12c side wall

[0036] 13 Exhaust side 14 Exhaust outlet

[0037] 16 Electrode terminal 20 Monomer cover

[0038] 22 Exhaust opening 24 Opening for electrode terminal DETAILED DESCRIPTION

[0039] Reference will now be made in detail to embodiments, examples of which are shown in the accompanying drawings. Aspects and features of the embodiments and methods of implementing the same will be described with reference to the accompanying drawings. However, the present disclosure may be implemented in a variety of different forms and should not be construed as being limited to the embodiments shown here. Rather, these embodiments are provided as examples so that the present disclosure will be thorough and complete and will fully convey the aspects and features of the present disclosure to those skilled in the art.

[0040] Therefore, processes, elements, and techniques that are not considered necessary for one of ordinary skill in the art to fully understand the aspects and features of the present disclosure may not be described.

[0041] It will be understood that when an element or layer is referred to as being "on," "connected to," or "coupled to" another element or layer, it may be directly on, directly connected to, or coupled to the other element or layer, or there may be one or more intervening elements or layers. When an element or layer is referred to as being "directly on," "directly connected to," or "directly coupled to" another element or layer, there may be no intervening elements or layers. For example, when a first element is described as being "coupled to" or "coupled to" a second element, the first element may be directly coupled to or coupled to the second element, or the first element may be indirectly coupled to or coupled to the second element via one or more intervening elements.

[0042] In the accompanying drawings, for the clarity of the illustration, the sizes of various elements, layers, etc. may be exaggerated. The same reference numerals refer to the same elements. As used herein, the term "and / or" includes any and all combinations of one or more associated listed items. In addition, when describing the embodiments of the present disclosure, the use of "may" relates to "one or more embodiments of the present disclosure". Statements such as "at least one of ... " and "any one of ... " modify the entire column of elements when following a column of elements, rather than modifying the individual elements in the list. For example, the statement "at least one of a, b or c" represents only a, only b, only c, both a and b, both a and c, both b and c, all of a, b and c or their variants. As used herein, the terms "use (use)", "use ... (using)" and "used (used)" can be considered to be synonymous with the terms "utilize (utilize)", "utilize ... (utilizing)" and "utilized (utilized)" respectively.

[0043] It will be understood that although the terms first, second, third, etc. can be used here to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are used to distinguish an element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teaching of the example embodiments, the first element, component, region, layer or part discussed below can be referred to as the second element, component, region, layer or part.

[0044] For ease of description, spatial relationship terms such as "under", "below", "below", "above", "on", etc. may be used here to describe the relationship between one element or feature and another one or more elements or features as shown in the drawings. For example, the terms "upper" and "lower" are defined according to the z-axis, so that, as an example, the upper cover is located at the upper part of the z-axis and the lower cover is located at the lower part of the z-axis. It will be understood that in addition to the orientations drawn in the drawings, the spatial relationship terms are intended to cover different orientations of the device in use or operation. For example, if the device in the drawings is turned over, the elements described as being "below" or "below" other elements or features will be oriented as being "above" or "above" other elements or features. Therefore, the term "below" can cover both the above and below orientations. The device can be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relationship descriptors used here should be interpreted accordingly.

[0045] The terms used herein are for the purpose of describing the embodiments of the present disclosure and are not intended to limit the present disclosure. As used herein, the singular forms "a" and "an" are intended to also include plural forms, unless the context clearly indicates otherwise. It will also be understood that when used in this specification, the terms "includes", "including", "comprises" and / or "comprising" specify the presence of the features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0046] As used herein, the terms "substantially," "about," and similar terms are used as terms of approximation, not terms of degree, and are intended to account for the inherent deviations in measured or calculated values ​​that one of ordinary skill in the art would recognize. In addition, if the term "substantially" is used in conjunction with a feature that can be expressed using a numerical value, the term "substantially" means a range of + / - 5% of that value centered around that value.

[0047] According to one embodiment of the present disclosure, a battery cell is provided. The battery cell may be one of a plurality of battery cells of a traction battery of an electric vehicle. The battery cell includes a cell housing, and an electrochemical cell (e.g., an electrode assembly) is arranged within the cell housing. The cell housing may be a metal cell housing; for example, the cell housing may be composed of metal or may include metal, or may mainly include metal. In one embodiment, the metal cell housing may be an aluminum cell housing; for example, the cell housing may be composed of aluminum or may include aluminum, or may mainly include aluminum. The metal cell housing is conductive at voltages that may occur during normal operation of a battery cell as part of a traction battery of an electric vehicle and / or at voltages that may occur during thermal runaway within the battery cell.

[0048] In one embodiment, the monolithic housing has a top side, a bottom side and side walls. The monolithic housing may be prismatic, for example in the form of a cuboid. In such an embodiment, the monolithic housing may have six sides—a top side, a bottom side and four side walls.

[0049] In another embodiment, the cell housing (and thus the battery cell) may be cylindrical having two circular regions parallel to each other and a side surface connecting the two circular surfaces (or extending between the two circular surfaces), the side wall forming the side surface of the cylinder. For example, in a cylindrical cell housing (and thus a cylindrical battery cell), the side surface of the cylinder may be considered to form the side wall, one of the circular regions may be considered to form the top side, and the other of the circular regions may be considered to form the bottom side of the cell housing.

[0050] The battery cell has at least one exhaust outlet on the exhaust side of the battery cell, which exhaust side may also be the terminal side of the battery cell, i.e., the side including electrode terminals for electrically connecting the battery cell to other battery cells and / or to the electric motor of the electric vehicle. The exhaust outlet is configured to allow exhaust gas flow to escape the battery cell during thermal runaway of the battery cell. The exhaust valve may be arranged at (or in) the exhaust outlet. The exhaust side of the battery cell may be the top side and / or the bottom side of the battery cell; that is, the exhaust outlet may be provided at the top side and / or the bottom side of the battery cell.

[0051] In addition, a battery cell according to an embodiment of the present disclosure includes a cell cover covering the outer surface of the cell housing. As used herein, covering means that the cell cover completely surrounds or substantially surrounds the cell housing, wherein the cell cover is in direct contact with the outer surface of the cell housing. For example, the cell cover covers or surrounds or envelops the cell housing from the outside. In one embodiment, the cell cover completely covers the outer surface of the cell housing. In other words, the entire outer surface of the cell housing may be covered by the cell cover. However, the exhaust outlet of the battery cell and the electrode terminals of the battery cell are not covered by the cell cover. Therefore, the top side, bottom side and all side walls of the cell housing are covered by the cell cover. In a prismatic cell housing, the top side, bottom side and all four side walls may be covered (e.g., completely covered) by the cell cover. In a cylindrical battery cell, two circular surfaces and the side surface may be covered (e.g., completely covered) by the cell cover.

[0052] The cell cover comprises or consists of a fiber mat embedded in a matrix support material so that the combination of the fiber mat and the matrix support material forms a composite material. Within the fiber mat, the fibers are not loosely arranged, but are, for example, purposefully or intentionally arranged. For example, the fiber mat is a textile, that is, the fibers are woven or interwoven to form a fabric / mat. The matrix support material provides stability to the fiber mat. The cell cover includes an exhaust opening aligned with the exhaust outlet of the battery cell on the exhaust side for allowing the exhaust gas flow to pass through the cell cover. The exhaust opening may be (or may include) a cut in the cell cover. The exhaust opening may correspond in form and size to the form and size of the exhaust outlet aligned therewith. In addition, the exhaust opening may be a simple cut along a line. Such a cut may be sufficient to allow the exhaust gas flow to pass through it, while the cell cover can still prevent pollutants from entering the battery cell from the outside through the exhaust outlet. The cell cover may be fixed to the outer surface of the cell housing, for example, by glue.

[0053] According to an embodiment of the present disclosure, the cell cover provides thermally stable electrical insulation to the battery cell by covering the outer surface of the cell housing. The cell cover provides electrical insulation and thermal insulation. Since the cell cover surrounds the cell housing on all sides, the battery cell is (electrically) insulated on all sides. The battery cell is insulated from any adjacent battery cell. As explained above, due to high temperatures (about 1000°C and higher), the cell insulation such as plastic sheets melts during thermal runaway, which leads to the loss of electrical insulation. This problem is overcome by the cell cover according to an embodiment of the present disclosure because the cell cover can withstand these temperatures. Due to its composite material, the cell cover provides improved insulation during thermal runaway of the battery cell itself or adjacent battery cells, because at the high temperatures occurring during thermal runaway, the matrix support material may be destroyed, but the fiber mat can still maintain its structure and its electrical insulation properties. The composite material ensures that the cell cover is stable but still flexible, which is easy to assemble. However, although not mechanically rigid, the cell cover provides sufficient electrical insulation as well as sufficient thermal insulation, thereby mitigating or preventing thermal runaway from spreading to other battery cells. Thus, the cell cover according to an embodiment of the present disclosure provides a heat-resistant cover on the outside of the cell housing so that in the event of thermal runaway, the cell housing remains electrically insulated (e.g., its electrical insulation remains intact). Due to the exhaust opening provided in the cell cover, the battery cell can be exhausted through its exhaust outlet in a controlled manner. Thus, the cell cover covers the exhaust side (e.g., the top side or bottom side of the cell housing) while still allowing the exhaust gas flow to leave the battery cell. Thus, the cell cover completely covers the outer surface of the battery cell, that is, the top side, bottom side, and any side wall except the exhaust outlet and except the electrode terminal. The cell cover can provide thermal insulation for the battery cell by, for example, protecting the battery cell from any exhaust products that may be deposited on the cell cover from the outside (e.g., from adjacent battery cells). Therefore, the battery cell according to an embodiment of the present disclosure is able to maintain its electrical insulation during thermal runaway, and thus handle thermal runaway more safely. The cell cover can provide "integrated" insulation that fits tightly with the cell housing.

[0054] According to one embodiment, the battery cell includes an electrode terminal arranged at the top side of the battery cell, and the cell cover has an opening through which the electrode terminal extends. The electrode terminal may also be referred to as a cell terminal. The electrode terminal is an electrode of the battery cell, which is used to obtain electrical energy stored in the electrochemical cell and is used for the electrical connection of the battery cell to one or more other battery cells of the battery module / system. Adjacent battery cells can be interconnected with each other by contacting an electrical connection means (such as a wire or a bus bar) of the electrode terminal of the corresponding battery cell. The electrode terminal extends through the cell cover so that the cell cover does not cover the electrode terminal. Therefore, the cell cover completely covers the outer surface of the battery cell, that is, the top side, the bottom side, and any side wall, except for the exhaust outlet and except for the electrode terminal. In other words, among the entire outer surface of the cell housing, and therefore among the entire outer surface of the battery cell, only the electrode terminal and the exhaust outlet are exposed by the cell cover (e.g., not covered by the cell cover). As explained, the cell cover covering the entire outer surface of the cell housing provides improved insulation during thermal runaway. The cell cover not covering the electrode terminal allows easy electrical connection of the electrode terminal with, for example, another battery cell. However, the electrode terminal may be covered by the covering element after the battery cell has been placed into the battery housing of the battery system together with the other battery cells (i.e. after assembly of the battery system). The opening for the electrode terminal may be formed as a cutout in the cell cover, as this is easy to manufacture.

[0055] According to an embodiment, the fiber mat comprises one or more of the following: glass fibers, basalt fibers, mica fibers. As described above, these fibers can form a textile. Mica can refer to a mica silicate mineral. The matrix support material is or includes a resin and / or a glue. The matrix support material is or includes an epoxy resin and / or a polyurethane adhesive. These fibers and the matrix support material provide a flexible and thermally stable monomer cover that can be easily arranged to cover the (entire) outer surface of the monomer housing (as described above) while providing sufficient electrical insulation even during thermal runaway.

[0056] According to one embodiment, the cell cover further comprises a flame retardant. The flame retardant is activated by the high temperatures occurring during thermal runaway and prevents or at least slows down further heat propagation. The flame retardant further improves the ability of the cell cover to withstand the high temperatures occurring during thermal runaway, so that the cell cover provides reliable electrical insulation of the battery cell.

[0057] According to one embodiment, the composite material of the cell cover is or includes a FR-4 composite material. According to the National Electrical Manufacturers Association (NEMA) rating designation for glass-reinforced epoxy laminates, FR-4 is a composite material consisting of woven fiberglass fabric and epoxy resin adhesive that is flame retardant (e.g., self-extinguishing). The FR-4 composite material is suitable for withstanding the high temperatures that occur during thermal runaway and is therefore suitable for providing reliable electrical insulation of the battery cell.

[0058] According to one embodiment, the monomer cover is adapted to the contour of the outer surface of the monomer housing (including the top side, bottom side and side walls). Adaptation to the contour means that the monomer cover has a shape corresponding to the shape of the element it covers. The contour or form of the monomer cover can be adapted to the contour of the outer surface of the monomer housing, such as the top side, bottom side and all side walls of the monomer housing. The monomer cover is suitable for such adaptation because it is relatively flexible due to the fiber mat, but can still maintain its shape due to the matrix support material. Such adaptation of the monomer cover to the covered part provides improved electrical and thermal insulation. In addition, this makes it rare or no chance for exhaust products to reach the covered part, thus allowing reliable shielding.

[0059] Another embodiment of the present disclosure relates to a battery system, which includes one or more of the above-mentioned battery cells. The battery system may include a battery housing and a plurality of battery cells contained in the housing, thereby forming a battery housing. The battery housing may also be considered as a cell compartment of the battery cell. The battery cells may be interconnected by electrical connections (such as bus bars) that contact the corresponding electrodes / cell terminals of the battery cells to form one or more battery modules / battery packs. The battery cells may be arranged to form one or more battery packs, and in the battery packs, the battery cells are electrically interconnected in series and / or in parallel. A plurality of such battery packs may form a battery module. Two or more battery packs may be stacked to form a cell stack. The battery cell may be, for example, a prismatic or cylindrical cell. Each battery cell may include a metal housing having a top side, a bottom side, and a sidewall extending from the top side to the bottom side. Each battery cell may include an exhaust outlet at the exhaust side of the battery cell, the exhaust outlet allowing the exhaust gas flow to escape the battery cell during thermal runaway. An exhaust valve may be provided at the exhaust outlet. The exhaust side may be the top side and / or the bottom side of the battery cell. For example, exhaust outlets may be provided on the top side and / or the bottom side of the battery cell.Each battery cell may include a cell cover as described above.

[0060] Another embodiment of the present disclosure is directed to an electric vehicle including the battery system as described above.

[0061] Another embodiment of the present disclosure is directed to an energy storage system (ESS) including the battery system as described above.

[0062] Figure 1 and Figure 2 A battery cell 10 according to an embodiment of the present disclosure is schematically illustrated. Figure 1 A cross-sectional view of a battery cell 10 is shown, Figure 2 The battery cell 10 is shown from above.

[0063] The battery cell 10 includes an electrochemical cell enclosed by a cell housing 12. The cell housing 12 includes aluminum. Thus, the cell housing 12 is a metal cell housing that is conductive at least at a sufficiently high differential voltage (eg, at least about 20V).

[0064] The cell housing 12 has a rectangular parallelepiped shape and has a top side 12a, a bottom side 12b and four side walls 12c. The top side 12a forms (or is) an exhaust side 13 of the battery cell 10, because the battery cell 10 includes an exhaust outlet 14 on this side. During thermal runaway inside the battery cell 10, the exhaust gas flow can leave the battery cell 10 through the exhaust outlet 14. An exhaust valve can be provided at (or in) the exhaust outlet 14. In addition, the battery cell 10 includes an electrode terminal 16 at the top side 12a, so that at the top side 12a of the cell housing 12, the electrode terminal 16 forms an electrode.

[0065] The battery cell 10 also includes a cell cover 20 that surrounds the battery cell 10 from all sides, thereby covering the outer surface of the cell housing 12, including the top side 12a, the bottom side 12b and all the side walls 12c. The cell cover 20 directly abuts the outer surface of the cell housing 12, and thus abuts the aluminum material. The cell cover 20 is adapted to the contour of the outer surface of the cell housing 12 (i.e., the top side 12a, the bottom side 12b and the side walls 12c). The cell cover 20 can be directly glued to the outer surface of the cell housing 12 and in close contact therewith.

[0066] The cell cover 20 has openings only at the position of the electrode terminal 16 and at the position of the exhaust outlet 14. For example, the cell cover 20 includes an exhaust opening 22 at the top side 12a of the battery cell 10, which is aligned with the exhaust outlet 14. The exhaust opening 22 can be formed by a notch or a cutout. Therefore, the exhaust gas flow discharged outward from the exhaust outlet 14 can pass through the cell cover 20 to the outside of the battery cell 10. In addition, the cell cover 20 has two openings 24, one for each of the two electrode terminals 16. The electrode terminal 16 extends through the opening 24 and therefore passes through the cell cover 20. The opening 24 can be formed by a cutout.

[0067] In one embodiment, the cell cover 20 is made of a FR-4 composite material that includes glass and / or basalt fibers in the form of a fiber mat that is tensioned (or fixed) by a composite glue (such as epoxy or polyurethane). The cell cover 20 is flexible while providing improved thermal and electrical insulation properties compared to other cell insulations such as plastic sheets.

[0068] During thermal runaway, temperatures of about 1000° C. and higher may be reached, which the cell cover 20 can withstand due to the cell cover 20. The cell cover 20 fully protects the battery cell 10 from electrical faults, such as internal short circuits or arc discharges between adjacent cells, because the cell cover 20 maintains its electrical insulation properties even during thermal runaway. Since the cell cover 20 covers the entire cell housing from all sides, the battery cell 10 is fully insulated. The cell cover 20 provides an “integrated” insulation that fits tightly with the cell housing 12. Therefore, according to an embodiment of the present disclosure, the battery cell 10 is able to maintain its electrical insulation during thermal runaway and handle thermal runaway more safely.

[0069] Figure 3 A battery cell 10' according to another embodiment of the present disclosure is shown. The battery cell 10' is a cylindrical battery cell having a cell housing 12 having a cylindrical shape. In this embodiment, the cell housing 12 also has a top side 12a and a bottom side 12b formed by the circular surface of the cell housing 12 and a side wall 12c formed by the side surface of the cell housing 12. In this embodiment, the cell cover 20 therefore also has a cylindrical shape and completely covers the cell housing 12 from all sides, except for the opening 24 through which the electrode terminal 16 extends and the exhaust opening 22 aligned with the exhaust outlet 14. Therefore, according to an embodiment of the present disclosure, a cylindrical battery cell may also be provided with a cell cover 20, thereby providing thermally stable electrical insulation.

Claims

1. A battery cell, comprising: a metal cell housing having a top side, a bottom side and side walls, the metal cell housing having an exhaust outlet at the top side and / or the bottom side of the metal cell housing to allow exhaust gas flow to exit from the metal cell housing to form an exhaust side of the battery cell; and a cell cover covering the outer surfaces of the top side, the bottom side and the side walls of the metal cell housing, the cell cover comprising a composite material including a fiber mat embedded in a matrix support material, The monolithic cover has an exhaust opening at the exhaust side and aligned with the exhaust outlet to allow the exhaust gas flow to pass through the monolithic cover.

2. The battery cell according to claim 1, further comprising an electrode terminal arranged at the top side of the battery cell, The single body cover has an opening through which the electrode terminal extends. 3 . The battery cell according to claim 1 , wherein the fiber mat comprises glass fiber, basalt fiber and / or mica fiber. 4 . The battery cell according to claim 1 , wherein the matrix support material comprises a resin and / or a glue. 5 . The battery cell of claim 1 , wherein the matrix support material comprises an epoxy resin and / or a polyurethane binder. 6 . The battery cell according to claim 1 , wherein the cell cover further comprises a flame retardant.

7. The battery cell according to claim 1, wherein the composite material is a FR-4 composite material.

8. The battery cell of claim 1, wherein the cell cover conforms to the contours of the outer surfaces of the top side, the bottom side, and the sidewalls of the metal cell casing.

9. A battery system comprising a battery housing accommodating a plurality of battery cells according to claim 1, The battery cells are arranged to form one or more battery packs and / or battery modules.

10. An electric vehicle comprising the battery system according to claim 9.

11. An electric vehicle comprising the battery cell according to claim 1.

12. An energy storage system comprising the battery system according to claim 9.

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