Battery system including improved cell cover attachment and electric vehicle including same

Abstract

A battery system and an electric vehicle including the same are disclosed, the battery system including: a plurality of battery cells each having an exhaust gas outlet for discharging an exhaust gas flow at an exhaust gas side thereof; and a cover member covering the exhaust side of at least one battery cell of the plurality of battery cells to protect the at least one battery cell from the exhaust airflow. The cover element is sealed directly to the exhaust side of the at least one battery cell by an adhesive extending around the exhaust outlet.

Description

Technical Field

[0001] The embodiments of this disclosure relate to battery systems. Background Technology

[0002] Recently, vehicles using electricity as a power source for transporting goods and people have been developed. Such electric vehicles are automobiles that are permanently or temporarily powered by an electric motor using energy stored in rechargeable batteries. Electric vehicles can be powered solely by batteries (so-called battery electric vehicles "BEVs"), or they can include a combination of an electric motor and, for example, a conventional internal combustion engine (so-called plug-in hybrid electric vehicles "PHEVs"). BEVs and PHEVs use high-capacity rechargeable batteries designed to provide power for propulsion over a sustained period of time.

[0003] Typically, a rechargeable (or secondary) battery cell includes an electrode assembly comprising a positive electrode, a negative electrode, and a separator interposed between the electrodes. A solid or liquid electrolyte allows ions to move during the charging and discharging of the battery cell. The electrode assembly is located (e.g., housed in) a casing, with electrode terminals positioned outside the casing establishing conductive connections to the electrodes. The casing may have, for example, a cylindrical or rectangular shape.

[0004] A battery module is formed by connecting multiple battery cells together in series or parallel. For example, a battery module is formed by interconnecting the electrode terminals of multiple battery cells in a number and configuration depending on the desired power, thereby providing a high-power rechargeable battery.

[0005] Battery modules can be constructed in a block design or a modular design. In a block design, each battery cell is integrated into a common current collector structure and a common battery management system, and the cells are arranged in a housing. In a modular design, multiple battery cells are connected together to form sub-modules, and several sub-modules are connected together to form a battery module. In automotive applications, battery systems typically include multiple battery modules connected in series to provide a desired voltage.

[0006] A battery pack is an assembly of any number (usually the same) of battery modules or individual battery cells. These modules or cells can be configured in series, parallel, or a combination of both to provide desired voltage, capacity, and / or power density. The components of a battery pack include individual battery modules and interconnections that provide conductivity between the modules.

[0007] The exothermic decomposition of a single cell component can lead to what is known as thermal runaway. Generally, thermal runaway describes a process that accelerates due to rising temperatures, releasing energy that further increases in temperature. Thermal runaway occurs when conditions change in a way that alters the temperature, often leading to further increases, and often results in destructive consequences. In rechargeable battery systems, thermal runaway is associated with a strongly exothermic reaction accelerated by rising temperatures. During thermal runaway, the temperature of a single cell rises extremely rapidly, and the stored energy is released very suddenly. In extreme cases, thermal runaway can cause a single cell to explode and ignite a fire. In milder cases, it can damage the cell beyond repair.

[0008] When a battery cell is heated above its critical temperature (e.g., above approximately 150°C), it may enter thermal runaway. Typically, temperatures outside the safe zone on the low or high side can cause irreversible damage to the battery cell, potentially triggering thermal runaway. Thermal runaway can also occur due to internal or external short circuits within the battery cell or poor battery maintenance. For example, overcharging or fast charging can lead to thermal runaway.

[0009] During thermal runaway, the faulty battery cell can reach temperatures exceeding approximately 700°C. Furthermore, a large amount of hot gas is ejected from the inside of the faulty cell into the battery pack through venting openings in the cell casing. The main components of the emitted gases are H2, CO2, CO, electrolyte vapor, and other hydrocarbons. Therefore, the emitted gases are flammable and potentially toxic. The emitted gases also cause an increase in pressure within the battery pack. In the worst-case scenario, the high temperature causes this process (e.g., thermal runaway) to spread to adjacent cells, leading to a fire within the battery pack. At this stage, the fire is difficult to extinguish.

[0010] The Battery Management System (BMS) is crucial for the safe operation and optimal performance of rechargeable battery cells, and reduces or minimizes the possibility of thermal runaway. For example, if the BMS detects that the temperature is too high, it can regulate the temperature by controlling the cooling fans. If the battery cells cannot be adequately cooled and return to safe conditions, the BMS will shut down the necessary battery cells to protect the entire system.

[0011] The traditional venting design for battery modules involves allowing the exhaust gas from the individual battery cells to expand into the battery casing and escape to the outside (e.g., to the environment surrounding the battery casing) through a casing vent valve. However, this design causes the exhaust gas to heat components inside the battery casing, such as other battery cells. Furthermore, particles from the exhaust gas may deposit on the battery cells, potentially leading to heat propagation and possibly inducing thermal runaway in adjacent cells. To protect the battery cells, a cover element can be provided that covers the venting side of the battery cells.

[0012] Such a cover element can have a through-hole-shaped vent opening aligned with the vent outlet of a battery cell to allow vent gas to pass through the cover element in the event of thermal runaway of one of the covered battery cells. After passing through the cover element, particles of the discharged vent gas can deposit on the cover element. However, particles of the vent gas can pass through another vent opening of the cover element aligned with the vent outlet of another battery cell and may come into contact with (or enter) that other battery cell. This can lead to heat propagation in that other battery cell and, in the worst case, trigger thermal runaway in that other battery cell.

[0013] To address this issue, a cover element can be provided that is thin enough to rupture at a section aligned with and corresponding to the exhaust outlet of the battery cell when exposed to high pressure from the exhaust gas stream exiting from one of the covered battery cells affected by thermal runaway. Furthermore, the cover element may include perforations corresponding to the exhaust outlet at the section aligned with the exhaust outlet to provide a fracture point (e.g., a predetermined fracture point) that can rupture upon exposure to the high pressure of the exhaust gas stream. The cover element is typically adhered to the surface of the battery cell via two adhesive strips extending in a straight line along the stacking direction of the battery cells to span multiple battery cells, with one adhesive strip positioned on each side of the exhaust outlet of the battery cell.

[0014] However, these solutions carry the risk that, before the cover element ruptures, it may bend outward due to the pressure of the exhaust gas flow, causing it to lift from the cell adjacent to the affected cell. This allows exhaust gas to flow beneath the cover element into the adjacent cell. In this scenario, the two adhesive strips can form a channel for the exhaust gas flow, extending along the surface of the cell from one cell to the next. This could lead to heat propagation within the adjacent cell, potentially triggering thermal runaway in the worst-case scenario. Summary of the Invention

[0015] According to embodiments of this disclosure, a battery system is provided that can more safely handle thermal runaway in one or more of its battery cells.

[0016] This disclosure is defined by the appended claims and their equivalents. The following description is subject to this limitation. Any disclosure beyond the scope of the claims and their equivalents is intended for illustrative and comparative purposes.

[0017] According to one embodiment of this disclosure, a battery system includes: a plurality of battery cells, each battery cell having an exhaust outlet on its exhaust side for discharging an exhaust gas flow; and a cover element covering the exhaust side of at least one of the plurality of battery cells to protect the at least one battery cell from the exhaust gas flow. The cover element is directly sealed to the exhaust side of the at least one battery cell by an adhesive extending around the exhaust outlet.

[0018] According to embodiments of this disclosure, the cover element can be integrally formed from a sheet material.

[0019] According to embodiments of this disclosure, the cover element may be a mica sheet.

[0020] According to embodiments of this disclosure, the adhesive can be applied to the entire exhaust side of the battery cell, excluding the exhaust outlet.

[0021] According to embodiments of this disclosure, the adhesive may include adhesive beads.

[0022] According to embodiments of this disclosure, the adhesive may include a gap filler.

[0023] According to embodiments of this disclosure, the cover element may be configured to rupture at a section opposite the exhaust outlet due to the exhaust gas flow leaving the covered exhaust outlet.

[0024] According to embodiments of this disclosure, the cover element may have a material-weakened portion opposite to the exhaust outlet of the battery cell.

[0025] Another embodiment of this disclosure provides an electric vehicle that includes the battery system described above.

[0026] Further aspects and features of this disclosure may be understood from the dependent claims and / or the following description. Attached Figure Description

[0027] The aspects and features of this disclosure will become apparent to those skilled in the art from the detailed description of embodiments thereof with reference to the accompanying drawings, in which:

[0028] Figure 1 This is a schematic top view of a battery system according to an embodiment.

[0029] Figure 2 yes Figure 1 A schematic cross-sectional view of the battery system shown.

[0030] Some reference symbols

[0031] 12 battery cells

[0032] 13 top side

[0033] 14 exhaust outlets

[0034] 16 Adhesives

[0035] 20 cover components

[0036] 30 wall components

[0037] 32 protrusions

[0038] 34 exhaust channels

[0039] 100 battery system

[0040] V exhaust airflow Detailed Implementation

[0041] Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. Aspects and features of this disclosure and methods of implementation thereof will be described with reference to the accompanying drawings. However, this disclosure may be implemented in a variety of different forms and should not be construed as limited to the embodiments shown herein. Rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete and will fully convey to those skilled in the art the aspects and features of this disclosure.

[0042] Therefore, processes, elements, and techniques that are not considered essential for a full understanding of the aspects and features of this disclosure by one of ordinary skill in the art may be omitted or only briefly described. It will be understood that when an element or layer is referred to as being "on" another element or layer, "connected to," or "bonded to" another element or layer, it may be directly on, directly connected to, or bonded to the other element or layer, or there may be one or more intermediary elements or layers. When an element or layer is referred to as being "directly on" another element or layer, "directly connected to," or "directly bonded to" another element or layer, there are no intermediary elements or layers. For example, when a first element is described as being "bonded" or "connected" to a second element, the first element may be directly bonded to or connected to the second element, or the first element may be indirectly bonded to or connected to the second element via one or more intermediary elements.

[0043] In the figures, the dimensions of various elements, layers, etc., may be exaggerated for clarity. The same reference numerals denote the same elements. As used herein, the term “and / or” includes any and all combinations of one or more of the related listed items. Furthermore, when describing embodiments of this disclosure, the use of “may” refers to “one or more embodiments of this disclosure.” Expressions such as “at least one of…” and “any one of…”, when following a list of elements, modify the entire list of elements without modifying individual elements within that list. For example, the expression “at least one of a, b, or c” means only a, only b, only c, both a and b, both a and c, both b and c, all a, b, and c, or variations thereof. As used herein, the terms “use,” “using…,” and “being used” may be considered synonymous with the terms “utilize,” “using…,” and “being exploited,” respectively.

[0044] It will be understood that although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or segment from another element, component, region, layer, or segment. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0045] For ease of description, spatial relation terms such as “below,” “under,” “down,” “above,” and “above” are used herein to describe the relationship between one element or feature and another element or feature as shown in the figure. It will be understood that, in addition to the orientation depicted in the figure, spatial relation terms are also intended to cover different orientations of the device in use or operation. For example, if the device in the figure is flipped, the element described as “below” or “under” other elements or features will be oriented “above” or “above” other elements or features. Therefore, the term “below” can cover both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relation descriptors used herein should be interpreted accordingly.

[0046] The terminology used herein is for the purpose of describing embodiments of this disclosure and is not intended to limit this disclosure. As used herein, the singular form “a” is also intended to include the plural form unless the context clearly indicates otherwise. It will be further understood that, when used in this specification, the terms “comprising,” “including,” “including,” and / or “containing” indicate the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0047] In view of the whole of this disclosure, those skilled in the art will understand that each suitable feature of the various embodiments of this disclosure may be combined in part or in whole or in combination with each other, and may be technically linked and operated in a variety of suitable ways, and unless otherwise stated or implied, each embodiment may be implemented independently of each other or in combination with each other in any suitable way.

[0048] As used herein, the terms “substantially,” “about,” and similar terms are used as approximate terms rather than terms of degree and are intended to account for the inherent biases of measured or calculated values ​​that would be recognized by one of ordinary skill in the art. Furthermore, if the term “substantially” is used in combination with a feature that can be expressed numerically, the term “substantially” indicates a range of + / -5% of the value centered on that value.

[0049] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will also be understood that terms (such as those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and / or the context of this specification, and shall not be interpreted in an idealized or overly formal sense, unless expressly defined herein.

[0050] According to one embodiment of this disclosure, a battery system includes a plurality of battery cells. The battery cells may be housed within a battery casing of the battery system. The battery cells may be arranged or stacked along a stacking direction to form one or more cell stacks. The battery cells may be interconnected via electrical connectors (e.g., busbars) that contact the respective electrode terminals of the battery cells to form one or more battery modules / packs. The battery cells may be arranged to form one or more battery packs. In a battery pack, the battery cells may be electrically interconnected, for example, in series and / or in parallel, as described above. A plurality of these battery packs may form a battery module. The battery cells may be, for example, prismatic or cylindrical cells.

[0051] Each battery cell includes an exhaust outlet located on the exhaust side of the battery cell, which may be the terminal side of the battery cell where the electrode terminals of the battery cell are disposed. Each exhaust outlet is configured to allow the discharge of exhaust gas streams from the respective battery cell during thermal runaway. An exhaust valve may be provided at (or within) the exhaust outlet, which may open (e.g., burst) when a reference pressure (e.g., a predetermined pressure) is exceeded.

[0052] The battery system also includes heat-resistant cover elements or covers arranged to cover one or more of the battery cells at the vent side of one or more of the battery cells. For example, the cover element may cover multiple or all of the battery cells at multiple or all of the vent sides. In some embodiments, the cover element may span all battery cells or extend over all battery cells. In other embodiments, multiple cover elements may be provided, each covering one or a group of battery cells. The cover element may cover the top side of the battery cell(s). The cover element is directly sealed to each battery cell by an adhesive extending around the periphery of each vent (e.g., around each vent). For example, the cover element is adhered to the surface of each battery cell via adhesive. The adhesive may extend continuously around each vent (e.g., the adhesive may extend uninterruptedly around each vent). For example, each vent may be surrounded by an uninterrupted line of adhesive. The adhesive may be applied to the vent side of the battery cell (e.g., applied to the top side of the battery cell) such that it surrounds each vent. For example, the adhesive may be applied in the form of multiple beads or lines, each bead or line surrounding the vent.

[0053] According to embodiments of this disclosure, the cover element is securely adhered to the venting side of the battery cell via an adhesive extending around each vent. This provides a robust seal in every direction. For example, because the adhesive extends around each vent, each vent is sealed and isolated from the others, so that no vent gas flow exiting one vent would be directed to another battery cell. In other words, no vent gas flow is provided to extend along the surface of the battery cell from one battery cell to the next (e.g., below the cover element). Furthermore, for example, when the cover element is configured to rupture at the section opposite the venting outlet of the battery cell when exposed to the pressure of the vent gas flow exiting the covered battery cell affected by thermal runaway, the seal around the venting outlet ensures that the cover element is not bent outward or lifted by the pressure of the vent gas flow. Thus, heat propagation to adjacent battery cells and thermal runaway of adjacent battery cells are reliably prevented.

[0054] According to one embodiment, the cover element is integrally formed from a sheet material (e.g., monolithically formed). That is, the cover element can be formed from a single sheet material. This provides simplicity in manufacturing the cover element. Furthermore, the cover element can be firmly adhered to the battery cell via an adhesive, and the cover element can be allowed to crack at the section opposite the vent outlet.

[0055] According to an embodiment, the cover element is a mica sheet. That is, the sheet material can be a mica sheet. In other words, the cover element can be integrally formed from a mica sheet. Therefore, the cover element can include mica. Mica refers to mica silicate mineral. This mica sheet is heat-resistant, allowing the cover element to withstand any particle deposition from the exhaust gas flow onto the cover element. Furthermore, this mica sheet can be a suitable material that allows the cover element to break at a section opposite the exhaust outlet.

[0056] According to one embodiment, the entire venting side surface of the battery cell is provided with an adhesive, except for the vent outlet. For example, the adhesive may cover the entire venting side of the battery cell (e.g., all or the entire top side). Therefore, the cover element can be securely sealed to the entire surface to provide a safe and reliable seal between the cover element and the battery cell, which prevents the cover element from lifting.

[0057] According to the implementation, the adhesive is (or includes) adhesive beads. A bead refers to a raised area or line. For example, the adhesive can be applied in the form of a line. Each exhaust outlet can be surrounded by such adhesive beads. In other words, the adhesive can include multiple adhesive beads, each extending around one of the exhaust outlets. Providing the adhesive in the form of adhesive beads extending around the exhaust outlets can provide a strong and reliable seal from the cover element to the battery cell, which can prevent the cover element from lifting.

[0058] According to the embodiment, the adhesive is or includes a gap filler. The gap filler may be, for example, polyurethane, such as Demak Group's SEPUR114FR THIXO+DK001.

[0059] For example, the gap filler can be readily cured at room temperature (RT), eliminating the need for additional heating during application. The mixing ratio of the base resin to the curing agent can be 100:14, and its mixed viscosity at 25°C can be 1800 cps. It can provide a thermal conductivity of 0.7 W / m·K. Furthermore, the glass transition temperature range of -10 to +5°C allows the material to maintain flexibility even at lower temperatures, while its moderate hardness (Shore hardness 35-45) balances flexibility and durability. It can also be flame retardant, meeting the UL 94V0 electronic safety rating by self-extinguishing upon exposure to flame. It functions normally even in high-temperature environments, with a maximum operating temperature of 130°C.

[0060] According to one embodiment, the cover element is configured to rupture at a section opposite (e.g., aligned with) the exhaust outlet due to the pressure of the exhaust gas flow exiting the covered exhaust outlet. The cover element may be configured to have a specific maximum thickness (e.g., thin enough to rupture due to the exhaust gas flow). According to another embodiment, the cover element includes a material-weakened portion, such as a perforation, opposite the exhaust outlet of the battery cell. These material-weakened portions ensure that the cover element ruptures at the section opposite the exhaust outlet. Therefore, the cover element may include a perforation corresponding to the exhaust outlet at the section opposite the exhaust outlet to provide a rupture point (e.g., a predetermined rupture point) that can rupture upon exposure to the high pressure of the exhaust gas flow. This ensures that the exhaust gas flow can exit the lower battery cell affected by thermal runaway. Because the adhesive extends around the exhaust outlet, the cover element remains firmly held at the battery cell without lifting.

[0061] Embodiments of this disclosure also provide an electric vehicle that includes a battery system, such as a traction battery, as described herein.

[0062] Figure 1 This is a top view of a battery system 100 according to an embodiment of the present disclosure, without the cover element 20 (see, for example...). Figure 2 The battery system 100 includes a plurality of battery cells 12 arranged along a stacking direction d. Each battery cell 12 has an exhaust outlet 14 on its exhaust side for discharging an exhaust gas flow V in the event of thermal runaway. Each exhaust outlet 14 may include an exhaust valve. The exhaust side of the battery cell 12 forms a top side 13 of the battery cell 12.

[0063] Each exhaust outlet 14 is surrounded by an adhesive 16 (e.g., surrounded in a plan view), the adhesive 16 forming a continuous line (e.g., the adhesive 16 extends around the periphery of the exhaust outlet 14). The adhesive 16 may be a gap filler. The adhesive 16 may be or may include adhesive beads. Beads may refer to bulges or lines. The adhesive 16 seals the cover element 20 to the top side 13 of the battery cell 12 (e.g., see...). Figure 2 ).

[0064] Figure 2 This is a cross-sectional view of the battery system 100, showing a plurality of battery cells 12 covered by a cover element 20. The cover element 20 may be integrally formed from a mica sheet (e.g., it may be integrally formed). The cover element 20 may include perforations corresponding to an exhaust outlet 14 (e.g., in a section opposite or aligned with the exhaust outlet 14) to provide a fracture point (e.g., a predetermined fracture point) that can break upon exposure to an exhaust flow V (e.g., upon exposure to the pressure of the exhaust flow V).

[0065] The cover element 20 is directly sealed to the top side 13 (e.g., the vent side) of the battery cell 12 via adhesive 16, which extends around the periphery of each vent outlet 14.

[0066] refer to Figure 2 This illustrates a scenario where thermal runaway occurs in the rightmost cell 12, causing an exhaust gas flow V to exit from the exhaust outlet 14 of the rightmost cell 12. The cover element 20 ruptures due to the exhaust gas flow V in the section opposite (e.g., aligned with) the exhaust outlet 14. Figure 2 As shown in the diagram, the exhaust airflow V can be deflected by a protrusion 32 extending from the wall member 30 (which may form part of the battery housing) and can be guided along an exhaust passage 34 formed by the wall member 30 and the cover element 20 (or formed between the wall member 30 and the cover element 20).

[0067] The adhesive 16 surrounding each exhaust outlet 14 provides a circumferential seal that prevents the exhaust gas flow V from flowing toward adjacent battery cells 12 between the top side 13 and the cover element 20 (e.g., preventing the exhaust gas flow V from flowing toward adjacent battery cells 12 below the cover element 20). For example, the adhesive 16 extends around each exhaust outlet 14 such that each of the exhaust outlets 14 is sealed and isolated from the others, and no channel is created for the exhaust gas flow V to extend along the surface of the battery cells 12 from one battery cell 12 to the next, which may occur if the adhesive 16 is applied in a straight line across multiple battery cells 12.

[0068] Furthermore, the adhesive 16 surrounding the exhaust outlet 14 ensures that the cover element 20 does not bend outward or lift due to the pressure of the exhaust flow V. Therefore, heat propagation to adjacent battery cells 12 and thermal runaway of adjacent battery cells 12 are reliably prevented.

Claims

1. A battery system, comprising: Multiple battery cells, each of which has an exhaust outlet on its exhaust side for discharging exhaust gas flow; as well as A cover element that covers the exhaust side of at least one of the plurality of battery cells to protect the at least one battery cell from the exhaust airflow. The cover element is directly sealed to the exhaust side of the at least one battery cell by an adhesive extending around the exhaust outlet.

2. The battery system of claim 1, wherein the cover element is integrally formed from a sheet material.

3. The battery system according to claim 1, wherein the cover element is a mica sheet.

4. The battery system of claim 1, wherein the adhesive is applied to the entire exhaust side of the plurality of battery cells, excluding the exhaust outlet.

5. The battery system of claim 1, wherein the adhesive comprises adhesive beads.

6. The battery system of claim 1, wherein the adhesive comprises a gap filler.

7. The battery system of claim 1, wherein the cover element is configured to rupture at a section opposite the exhaust outlet due to the exhaust gas flow exiting the covered exhaust outlet.

8. The battery system of claim 7, wherein the cover element has a material-weakened portion opposite to the exhaust outlet of the battery cell.

9. An electric vehicle comprising a battery system according to any one of claims 1 to 8.

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