BATTERY SYSTEM WITH IMPROVED THERMAL runaway PROCESSING AND ELECTRIC VEHICLE INCLUDING THE SAME

Abstract

A battery system and an electric vehicle including the same are provided. The battery system includes: a housing; a battery cell accommodated within the housing, the battery cell having an exhaust side, the exhaust side having an exhaust outlet; and a case cover sealing the battery cells in the case. The housing cover comprises an outer layer and an inner layer, the inner layer faces the exhaust side and forms part of the exhaust channel, and the outer layer is coated with an anti-corrosion coating on the outer surface of the outer layer. The outer layer and the inner layer are spaced apart from each other such that an air gap is formed between the outer layer and the inner layer.

Description

Technical Field

[0001] Aspects of the disclosed embodiments are directed to battery systems with improved thermal runaway management. Background Art

[0002] Recently, vehicles for transporting goods and people using electricity as a power source have been developed. Such electric vehicles are cars driven by electric motors using energy stored in rechargeable batteries. Electric vehicles can be powered by batteries alone, or can be hybrid vehicles powered by, for example, gasoline generators or hydrogen fuel cells. Hybrid vehicles can include a combination of electric motors and traditional internal combustion engines. Generally, electric vehicle batteries (EVB or traction batteries) are batteries used to power the propulsion of battery electric vehicles (BEVs). Electric vehicle batteries differ from starting batteries, lighting batteries, and ignition batteries in that they are designed to provide power for a sustained period of time. Rechargeable (or secondary) batteries differ from primary (or non-rechargeable) batteries in that they are designed to be repeatedly charged and discharged, while primary batteries are designed to provide only irreversible conversion of chemical energy to electrical energy. Low-capacity rechargeable batteries are used as power sources for small electronic devices (such as mobile phones, notebook computers, and cameras), while high-capacity rechargeable batteries are used as power sources for electric vehicles and hybrid vehicles, etc.

[0003] Generally, a rechargeable battery includes: an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; a housing that houses the electrode assembly; and an electrode terminal electrically connected to the electrode assembly. An electrolyte solution is injected into the housing to enable charging and discharging of the battery through an electrochemical reaction between the positive electrode, the negative electrode, and the electrolyte solution. The shape of the housing (such as a cylindrical or rectangular shape) can be selected based on the intended purpose of the battery. Lithium-ion (and similar lithium polymer) batteries, which are widely known for their use in laptops and consumer electronics, are the main form of secondary batteries used in recently developed electric vehicles.

[0004] The rechargeable battery 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 a motor drive of a hybrid vehicle. For example, depending on the desired amount of power and in order to provide a high power rechargeable battery, a battery module can be formed by interconnecting electrode terminals of a plurality of unit battery cells.

[0005] 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 collector structure and a common battery management system, and its units are arranged in a housing. In a 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 a plurality of battery modules connected 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 in parallel and then connected in series (XpYs) or cells connected in series and then connected in parallel (XsYp).

[0006] A battery pack is a group of any number of (usually identical) battery modules. The battery modules can be connected in series, in parallel, or in 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.

[0007] In order to provide thermal control of the battery pack, a thermal management system is required to safely use at least one battery module by effectively dissipating, releasing and / or dissipating the heat generated from its rechargeable batteries. If the heat dissipation, release and / or dissipation is not fully performed, a temperature difference may occur between the individual battery cells, so that at least one battery module may no longer generate the desired (or designed) amount of power. In addition, an increase in the internal temperature may cause abnormal reactions to occur therein. 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 is required to effectively dissipate the heat from the battery cells.

[0008] The exothermic decomposition of the cell assembly may lead to so-called thermal runaway. Generally, thermal runaway describes or refers to a process that is accelerated by the increased temperature, thereby releasing energy that further increases the temperature. In the case where the temperature increase changes the conditions in a way that causes the temperature to increase further, thermal runaway occurs, usually resulting in destructive results. In rechargeable battery systems, thermal runaway is associated with strong exothermic reactions that are accelerated by the increase in temperature. These exothermic reactions include the combustion of flammable gas components in the housing. For example, when the cell is heated above a critical temperature (e.g., above 150°C), the cell may turn into thermal runaway. The initial heating may be caused by a local fault (such as a short circuit inside the cell, heating from a defective electrical contact, a short circuit with an adjacent cell, etc.). During thermal runaway, a faulty battery cell (e.g., a battery cell with or experiencing a local fault) may reach a temperature of more than about 700°C. In addition, a large amount of hot gas is sprayed into the battery pack from the inside of the faulty battery cell through the exhaust port in the cell housing. The main components of the exhaust gas are H2, CO2, CO, electrolyte vapor and other hydrocarbons. Therefore, the exhaust gases are flammable and potentially toxic. The exhaust gases also cause the gas pressure inside the battery pack to increase.

[0009] A comparative venting concept for a battery is to allow a hot exhaust gas flow from a battery cell in a thermal runaway state to leave the battery cell, expand into the housing, and escape to the outside (e.g., the environment of the housing) through the housing vent valve. As a result, the exhaust gas flow heats the housing, for example, heating a portion of the housing opposite to the exhaust outlet of the battery cell (e.g., the housing cover). This may damage the anti-corrosion coating applied to the outer surface of the housing cover, and thus may expose the housing cover to corrosion. Summary of the invention

[0010] Aspects of some embodiments of the present disclosure provide a battery system that more safely handles thermal runaway of one or more of its battery cells without damaging components of the battery system.

[0011] The present disclosure is defined by the following claims and their equivalents. Any disclosure outside the scope of the claims is intended for illustrative and comparative purposes.

[0012] According to an embodiment of the present disclosure, a battery system includes: a housing; a battery cell contained in the housing, the battery cell having an exhaust side, the exhaust side having an exhaust outlet; and a housing cover that seals the battery cell in the housing. The housing cover includes an outer layer and an inner layer, the inner layer faces the exhaust side and forms a portion of the exhaust channel, and the outer layer is coated with an anti-corrosion coating on its outer surface. The outer layer and the inner layer are separated from each other, so that an air gap is formed between the outer layer and the inner layer.

[0013] In some embodiments, the inner layer can be a plate attached to the inner surface of the outer layer.

[0014] In some embodiments, the air gap may extend along a first length and the exhaust side may extend along a second length, and the first length may be less than the second length.

[0015] In some embodiments, the anti-corrosion coating may be a zinc nickel coating.

[0016] In some embodiments, both the outer layer and the inner layer may include steel or a steel alloy.

[0017] In some embodiments, the inner layer may include a guide protrusion protruding from the inner layer into the exhaust passage and toward the exhaust outlet to guide the exhaust gas flow discharged through the exhaust outlet into the exhaust passage.

[0018] In some embodiments, the guide protrusion may be a gas splitter protrusion having a conical shape with a tip facing the exhaust outlet, and may be configured to split the exhaust gas flow such that the exhaust gas flow is deflected to opposite sides of the exhaust passage.

[0019] In some embodiments, the battery system may further include a plurality of battery cells arranged inside the housing. The housing cover may include a plurality of steel plates attached to the inner surface of the outer layer of the housing cover, each of which may face the exhaust side of a corresponding one of the battery cells. The air gap may be formed as a free space confined between each steel plate and the outer layer of the housing cover.

[0020] According to some embodiments of the present disclosure, an electric vehicle includes the battery system described above.

[0021] Further aspects and features of the present disclosure will become apparent from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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:

[0023] Figure 1 is a cross-sectional view of a battery system according to an embodiment of the present disclosure.

[0024] Figure 2 yes Figure 1 A perspective view of the housing cover shown in FIG.

[0025] Figure 3 is a cross-sectional view of a battery system according to another embodiment of the present disclosure.

[0026] Reference numerals

[0027] 11 Shell

[0028] 12 battery cells

[0029] 13 Exhaust side

[0030] 14 Exhaust outlet

[0031] 20 housing cover

[0032] 22 Outer layer of the housing cover

[0033] 24 Inner layer of outer shell cover

[0034] 25 steel plate

[0035] 26 Anti-corrosion coating

[0036] 28 Exhaust channels

[0037] 30 air gap

[0038] 32 Shell exhaust valve

[0039] 34 guide protrusions

[0040] 100 battery system

[0041] 100' Battery System DETAILED DESCRIPTION

[0042] 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 suitable forms and should not be construed as being limited to the embodiments described herein. 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.

[0043] Therefore, processes, elements, and techniques 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.In the drawings, relative sizes of elements, layers, and regions may be exaggerated for clarity.

[0044] It will be understood that when an element or layer is referred to as being "on," "connected to," or "bonded to" another element or layer, it may be directly on, directly connected to, or directly bonded to another element or layer, or one or more intervening elements or layers may also be present. When an element or layer is referred to as being "directly on," "directly connected to," or "directly bonded to" another element or layer, there are no intervening elements or layers. For example, when a first element is described as being "bonded to" or "connected to" a second element, the first element may be directly bonded or connected to the second element, or the first element may be indirectly bonded or connected to the second element via one or more intervening elements.

[0045] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. The same reference numerals represent the same elements. In addition, when describing embodiments of the present disclosure, the use of "may" refers to "one or more embodiments of the present disclosure." In the following description of embodiments of the present disclosure, terms in the singular may include plural forms unless the context clearly indicates otherwise.

[0046] It will be understood that, although terms such as "first" and "second" are used to describe various suitable elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the present disclosure, the first element can be named as the second element, and similarly, the second element can be named as the first element. As used herein, the term "and / or" includes any and all combinations of one or more related listed items. When after a column of elements, statements such as "at least one of ... " modify the entire column of elements without modifying the individual elements in the column. 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 a, b and c or its variant. As used herein, the terms "use", "use ... " and "being used" can be considered to be synonymous with the terms "utilize", "utilize ... " and "being utilized" respectively.

[0047] As used herein, the terms "substantially," "about," and similar terms are used as terms of approximation, rather than 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 a value centered around that value.

[0048] It will also be understood that the terms “comprises,” “includes,” “including,” or “comprising” specify attributes, regions, fixed numbers, steps, processes, elements, components, and combinations thereof, but do not exclude other attributes, regions, fixed numbers, steps, processes, elements, components, and combinations thereof.

[0049] It will also be understood that when a film, region or element is referred to as being “on” or “on” another film, region or element, it can be directly on the other film, region or element or intervening films, regions or elements may also be present.

[0050] Here, the terms "upper" and "lower" are defined according to the z-axis. For 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. In the accompanying drawings, the size of the elements may be exaggerated for clarity. For example, in the accompanying drawings, the size or thickness of each element may be arbitrarily shown for the purpose of illustration, and therefore, the embodiments of the present disclosure should not be construed as being limited thereto.

[0051] In the following description of the embodiments of the present disclosure, terms in the singular form may include plural forms unless the context clearly indicates otherwise.

[0052] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and / or the context of this specification, and should not be interpreted in an idealized or overly formal sense, unless explicitly defined as such herein.

[0053] According to an embodiment of the present disclosure, a battery system includes a housing and at least one battery cell housed in the housing. The battery system may include a plurality of battery cells housed in the housing, and the battery cells form a battery pack. The battery cells may be interconnected via bus bars contacting the corresponding electrode terminals of the battery cells to form one or more battery modules. The battery cells may be, for example, prismatic or cylindrical cells. The battery cell may include an exhaust outlet located on the exhaust side of the battery cell, the exhaust outlet being, for example, the terminal side of the battery cell. The exhaust outlet allows the exhaust gas flow to escape the battery cell during thermal runaway. An exhaust valve may be provided at (or in) the exhaust outlet. The cover plate may cover the exhaust side, and the cover plate may have a through hole arranged at the exhaust outlet (e.g., aligned with the exhaust outlet) for allowing the exhaust gas flow to pass through the through hole.

[0054] The battery system may further include a housing cover. The housing cover may be considered as part of the housing. The housing cover may be a cover plate, for example, an upper cover plate arranged on the upper side / top side of the battery system or a lower cover plate arranged on the lower side / bottom side of the battery system. After the battery cell has been inserted into the base of the housing, the housing cover may be attached to the base of the housing. The housing cover seals (e.g., closes) the housing with respect to the outside (e.g., the environment of the battery system). The housing cover, in combination with other parts of the housing (such as the base of the housing), may seal the interior of the housing to be separated from the outside of the housing, so that the exhaust gas flow discharged by one or more battery cells during thermal runaway may escape the housing only at a channel or opening provided for this purpose (e.g., at an exhaust valve arranged in the housing wall of the housing), thereby escaping the battery system. The housing cover may seal the battery pack in an airtight manner to be separated from the outside.

[0055] The housing cover may include an outer layer and an inner layer. The inner layer and / or the outer layer may be made of steel. The outer layer may define the outer shell cover and the outer side of the housing, and the inner layer may define the outer shell cover and the inner side of the housing. For example, the inner layer of the housing cover faces the interior of the housing. For example, the inner layer may face the exhaust side of the battery cell. The inner layer may be arranged opposite to the exhaust outlet of the battery cell so that the exhaust gas flow leaving the exhaust outlet of the battery cell hits the inner layer and is deflected to the side of the housing by the inner layer. Therefore, the exhaust gas flow flows along the exhaust channel formed at least in part by the inner layer. The inner layer may define the boundary between the exhaust channel and one side. The exhaust channel may be defined on the other side by the exhaust side of the battery cell or by the above-mentioned cover plate (if present). Therefore, the exhaust channel may be formed by the inner layer and the exhaust side / cover plate. The exhaust gas flow discharged into the exhaust channel through the exhaust outlet during thermal runaway may be deflected by the inner layer and directed away from the exhaust outlet along the exhaust channel. As the exhaust gas flow flows from the exhaust outlet toward and strikes the inner layer of the housing cover, heat is transferred from the exhaust gas flow to the inner layer, thereby cooling the exhaust gas flow.

[0056] The outer layer of the housing cover may be coated with an anti-corrosion coating on its outer surface. The outer surface is the surface of the outer layer that faces the outside (e.g., the environment of the housing / battery system), and is therefore away from the inner layer of the housing cover. The anti-corrosion coating prevents or reduces corrosion of the outer layer, and therefore prevents or reduces corrosion of the housing cover by external sources. The anti-corrosion coating protects the housing cover from moisture that may come into contact with the housing cover from outside the housing / battery system. As described above, such an anti-corrosion coating may be damaged if exposed to high temperatures. For example, if the outer layer of the housing cover is in contact with the exhaust gas flow, the outer layer may heat up so that the anti-corrosion coating may be damaged. This may cause the housing cover to be corroded, which may in turn cause damage to the internal components of the battery system due to moisture entering the housing and / or, for example, exhaust gas leakage to the outside.

[0057] Therefore, according to an embodiment of the present disclosure, an inner layer is provided to protect the outer layer from the exhaust gas flow. An air gap is formed between the outer layer and the inner layer. The inner layer and the outer layer are away from each other (e.g., separated) so that the air gap is formed as a free space (e.g., an open space or a gap) confined between the inner layer and the outer layer. For example, the free space is confined between the cover plate and the outer shell cover, and the free space is filled with air. The air gap may be located at least at a portion of the outer shell cover that is arranged opposite to the exhaust outlet. According to an embodiment of the present disclosure, the outer shell cover may include a double-layer structure with an air gap therebetween.

[0058] When the exhaust gas flow leaving the exhaust outlet of the battery cell hits the inner layer and transfers heat to the inner layer, the air gap on the other side of the inner layer acts as a heat insulator, hindering the heat from being transferred from the inner layer to the outer layer of the outer shell cover. This prevents or reduces excessive heating of the outer layer of the outer shell cover, thereby preventing or reducing damage to the anti-corrosion coating of the outer layer. This improves (e.g., increases) the life expectancy of the coating, and thus improves the life expectancy of the battery system.

[0059] According to an embodiment, the inner layer can be formed by a plate attached to the inner surface of the outer layer of the outer shell cover. The inner surface of the outer layer is the surface of the outer layer facing the inside of the shell. As explained above, the plate is away from the outer layer to form an air gap between the plate and the outer layer. The plate can be a steel plate. The plate can be welded to the inner surface of the outer layer of the outer shell cover. When the battery system includes a plurality of battery cells, such a plate can be provided for each battery cell. For example, for each battery cell, such a plate can be attached to the inner surface of the outer layer of the outer shell cover, each plate facing the exhaust side, respectively, opposite to the exhaust outlet of one of the battery cells. Such a plate allows a relatively simple construction of the inner layer and the air gap, and therefore allows a relatively simple construction of the double-layer structure. Such a plate can be attached to an existing outer shell cover that is generally available. Such a plate can be used with a known battery system.

[0060] According to an embodiment, the air gap extends along a first length, the exhaust side extends along a second length, and the first length is less than the second length. As used herein, extending along the length means extending along the same direction or axis. Extending along the length may mean, for example, extending along the longitudinal axis of the battery cell. The length may be the direction or axis along which the exhaust gas mainly flows. For example, the inner layer may not extend along the entire (or entire) length of the exhaust side of the battery cell, but only along a portion of the exhaust side / battery cell. For example, the inner layer may only partially cover the exhaust side / battery cell in the area opposite to the exhaust outlet. After having been deflected by the inner layer as described above, the exhaust gas flow may contact the inner surface of the outer layer. The first length is determined or designed so that the exhaust gas flow has enough time to transfer heat to the inner layer, thereby sufficiently cooling the exhaust gas flow so as not to damage the outer layer and the coating on the outer layer when in contact with the outer layer. Therefore, the inner surface of the outer layer can be exposed to the exhaust gas at a distance far enough from the exhaust outlet so that the exhaust gas flow is cooled enough not to damage the coating on the outer layer. In one embodiment, the inner layer is formed by a plate. According to an embodiment, the air gap may contact less than the entire inner surface. In such an embodiment, the configuration of the air gap may be simpler than providing the air gap along the entire inner surface of the outer layer.

[0061] According to an embodiment, the anti-corrosion coating may be a zinc-nickel coating. Such a coating is very suitable for preventing or reducing corrosion of the outer layer of the housing cover, but is sensitive to temperature. Due to the double-layer structure of the housing cover with an air gap between the inner layer and the outer layer, thermal damage to the anti-corrosion coating by the exhaust gas flow can be prevented or at least significantly reduced.

[0062] According to an embodiment, both the outer layer and the inner layer may be made of steel or a steel alloy. Both the outer layer and the inner layer may be made of the same or substantially the same steel or steel alloy. These layers may all be made of steel or a steel alloy and / or may consist of, or consist essentially of, steel or a steel alloy. This allows the housing cover to be suitably rigid and / or suitably resilient.

[0063] According to an embodiment, the inner layer includes a guide protrusion formed as a protrusion in the inner layer and protruding into the exhaust channel toward the exhaust outlet to guide the exhaust gas flow discharged through the exhaust outlet and entering the exhaust channel. According to an embodiment, the guide protrusion may be a gas splitter protrusion having a conical shape facing the exhaust outlet and configured to split (or separate) the exhaust gas flow so that the exhaust gas flow is deflected to the opposite side of the exhaust channel. Therefore, in such an embodiment, the inner layer of the outer shell cover may include a guide protrusion, such as a protruding element for guiding the exhaust gas flow. The guide protrusion may be an integrated (or integral) guide protrusion; for example, the guide protrusion may be an integral part of the inner layer of the outer shell cover. For example, the inner layer may form a guide protrusion. For example, the guide protrusion may be a protrusion in the inner layer (or protruding from the inner layer). The guide protrusion protrudes toward the exhaust outlet of at least one battery cell, and thus protrudes into the exhaust channel. The guide protrusion is configured to guide the exhaust gas flow discharged through the exhaust outlet of the battery cell away from the exhaust outlet during a thermal runaway event. The guide protrusion is configured to divide the exhaust gas flow into two sub-flows and direct these sub-flows away from each other in opposite directions. The guide protrusion leads (or directs) the exhaust gas flow along the exhaust channel away from the exhaust outlet and the battery cell. This allows the exhaust gas flow to be quickly and reliably transported away. In addition, the guide protrusion can expand the surface area of ​​the inner layer so that the exhaust gas flow can transfer heat to the inner layer well to fully cool the exhaust gas flow. By using an aerodynamically efficient design, the guide protrusion can also reduce the pressure drop during the exhaust gas flow discharge. The guide protrusion can serve as a collector for molten particles carried by the exhaust gas flow. The inner layer and thus the guide protrusion can be formed by the above-mentioned (e.g. steel) plate to simplify the structure.

[0064] According to an embodiment, the battery system includes a plurality of battery cells arranged inside the housing, and the housing cover includes a plurality of plates attached to the inner surface of the outer layer of the housing cover. Each plate faces the exhaust side, opposite to the exhaust outlet of one of the battery cells, and the air gap is formed as a free space (or open space) confined between each steel plate and the outer layer of the housing cover. For example, the inner layer formed by the corresponding plate is away from the outer layer (e.g., separated from the outer layer) so that the air gap is formed as a free space confined between the corresponding plate and the outer layer. In one embodiment, the plate may be a steel plate. In such an embodiment, the battery system may be provided with a double-layer structure including air gaps corresponding to some or all of the battery cells in the battery cell. Each battery cell may have its own plate and therefore has its own double-layer structure including an air gap. The plate may be welded to the outer layer of the housing cover. The known housing cover may be retrofitted with such a plate, so that in the event of a thermal runaway event, the coating on the outer surface of the outer layer of the housing cover may be protected from damage.

[0065] The embodiments of the present disclosure are also applicable to an electric vehicle including the battery system described above.

[0066] Figure 1 A cross section of a battery system 100 is shown according to an embodiment of the present disclosure.

[0067] The battery system 100 includes a housing 11 and a plurality of battery cells 12 inside the housing 11. Figure 1 Only one battery cell 12 is shown in the figure. The battery cell 12 has an exhaust side 13 with an exhaust outlet 14 through which an exhaust gas flow can leave the battery cell 12 during a thermal runaway event inside the battery cell 12. The housing cover 20 covers the housing 11 to seal the battery system 100.

[0068] The housing cover 20 has a double-layer structure including (or formed of) an outer layer 22 and an inner layer 24. The outer layer 22 faces the outside of the battery system 100 and can prevent or reduce moisture and other contaminants from entering the battery system 100. The outer layer 22 can be coated with an anti-corrosion coating 26, such as a zinc-nickel coating, to prevent or reduce corrosion of the outer layer 22, and thus prevent or reduce corrosion of the housing cover 20 due to contact with moisture.

[0069] The inner layer 24 may be a steel plate 25 attached (e.g., welded) to the outer layer 22. Hereinafter, the terms "inner layer" and "steel plate" are used interchangeably. The inner layer 24 of the outer housing cover 20 faces the exhaust side 13 of the battery cell 12, opposite to the exhaust outlet 14. The inner layer 24 and the outer layer 22 are away from each other (e.g., spaced apart) so that the air gap 30 is formed as a free space confined between the inner layer 24 and the outer layer 22. Therefore, by attaching the steel plate 25 to the outer layer 22 of the outer housing cover 20, a double-layer structure having an air gap 30 inside is provided opposite to the exhaust outlet 14. An exhaust channel 28 may be formed between the inner layer 24 (i.e., the steel plate 25) and the exhaust side 13 of the battery cell 12.

[0070] When thermal runaway occurs inside the battery cell 12, the exhaust gas flow containing hot exhaust gas and particles is discharged from the battery cell 12 through the exhaust outlet 14 and enters the exhaust channel 28. The exhaust gas flow flows to the steel plate 25 and is deflected to the side by the steel plate 25, as shown by the dotted line. The exhaust gas flow can leave the housing 11 through the housing exhaust valve 32. The exhaust gas flow thereby transfers heat to the steel plate 25, which forms the inner layer 24 of the double-layer structure of the housing cover 20. The air in the air gap 30 acts as a heat insulator, preventing or at least significantly reducing heat transfer from the inner layer 24 to the outer layer 22. Therefore, at least while the exhaust gas flow is still hot, the outer layer 22 is protected from the exhaust gas flow. This prevents or reduces damage to the anti-corrosion coating 26 applied to the outer surface of the outer layer 22. Therefore, the double-layer structure with an air gap therebetween improves (e.g., increases) the expected life of the battery system 100.

[0071] The air gap 30 and thus the inner layer 24 need not extend along the entire length of the battery cell 12, but may extend (or be provided) only near the exhaust outlet 14 where the temperature of the exhaust gas flow is highest. After the exhaust gas flow is sufficiently cooled by at least transferring heat to the steel plate 25, the exhaust gas flow may contact the outer layer 22 of the housing cover 20. Thus, the air gap 30 may extend along a first length L1, which is less than the second length L2, such as Figure 1 As shown, the exhaust side 13 and thus the battery cell 12 extend along a second length L2. This may allow a simpler construction.

[0072] Figure 2 Shown from below Figure 1 The housing cover 20 shown in FIG. The housing cover 20 includes a plurality of steel plates 25 attached to an outer layer 22. For example, in the case where the steel plates 25 are attached to the housing cover 20, the housing cover 20 is provided with an outer layer 22 and an inner layer 24, and the inner layer 24 is made of (or formed of) the steel plates 25, respectively. Between each steel plate 25 and the outer layer 22 is a corresponding air gap 30 (see, for example, Figure 1For example, a plurality of double-layer structures are provided, each double-layer structure including an air gap between two layers. When placed on top of the housing 11, as Figure 1 As shown, each steel plate 25 can cover one battery cell 12. Thus, each battery cell 12 can be provided with a double-layer structure including an air gap, with the inner layer 24 forming the upper wall of the corresponding exhaust channel 28. Thus, the anti-corrosion coating 26 applied to the outer layer 22 is fully protected from the exhaust gas flow. The exhaust gas flow leaving the battery cell experiencing thermal runaway can then enter a common exhaust gas channel for all cells (e.g., open to all cells).

[0073] Figure 3 A battery system 100' according to another embodiment is shown. The battery system 100' differs from the above-described battery system 100 in that the steel plate 25 and thus the inner layer 24 are provided with guide protrusions 34. The guide protrusions 34 have a conical shape having a tip facing the exhaust outlet 14, and are configured to split (or separate) the exhaust gas flow so that the exhaust gas flow is deflected to the opposite side of the exhaust channel 28, as shown in FIG. Figure 3 This improves the heat transfer from the exhaust gas flow to the steel plate 25 and allows for better conveyance of the exhaust gas flow away from the exhaust outlet 14.

Claims

1. A battery system comprising: shell; a battery cell housed in the housing, the battery cell having a vent side, the vent side having an vent outlet; as well as a housing cover sealing the battery cell in the housing, the housing cover comprising an outer layer and an inner layer, the inner layer facing the exhaust side and forming a portion of the exhaust passage, the outer layer being coated with an anti-corrosion coating on an outer surface thereof, The outer layer and the inner layer are spaced apart from each other so that an air gap is formed between the outer layer and the inner layer.

2. The battery system according to claim 1, wherein: The inner layer is a plate attached to the inner surface of the outer layer.

3. The battery system according to claim 1, wherein: The air gap extends along a first length and the exhaust side extends along a second length, and Wherein, the first length is smaller than the second length.

4. The battery system according to claim 1, wherein: The anti-corrosion coating is a zinc-nickel coating.

5. The battery system according to claim 1, wherein: Both the outer layer and the inner layer comprise steel or a steel alloy.

6. The battery system according to claim 1, wherein: The inner layer includes a guide protrusion protruding from the inner layer into the exhaust passage and toward the exhaust outlet to guide the exhaust gas flow discharged through the exhaust outlet into the exhaust passage.

7. The battery system according to claim 6, wherein: The guide protrusion is a gas splitting protrusion having a conical shape having a tip facing the exhaust outlet, and is configured to separate the exhaust gas flow so that the exhaust gas flow is deflected to an opposite side of the exhaust passage.

8. The battery system according to claim 1, wherein: The battery system further includes a plurality of battery cells arranged inside the housing, wherein the housing cover comprises a plurality of steel plates attached to an inner surface of the outer layer of the housing cover, each of the steel plates facing the exhaust side of a corresponding one of the battery cells, and Therein, an air gap is formed as a free space confined between each of the steel plates and the outer layer of the housing cover.

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

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