Battery pack, battery system and method for transferring heat in battery pack

Abstract

The invention relates to a battery pack, a battery system and a method for transferring heat within the battery pack. A battery pack includes: a battery cell stack including a plurality of battery cells and a separator between two adjacent battery cells of the plurality of battery cells; and a cooler at a bottom side of the battery cell stack. The bottom side of the battery cell stack is opposite the exhaust side of the battery cell stack. The separator includes a thermally insulating core and a thermally conductive structure at a side surface of the separator, the side surface of the separator facing a side surface of one of the plurality of battery cells. The thermally conductive structure includes a central element centrally disposed in a side surface of the spacer and a trajectory extending from the central element into a peripheral region of the side surface of the spacer.

Description

Technical Field

[0001] Aspects of the disclosed embodiments relate to a battery pack, a battery system, and an insulator for a battery system. Background Art

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

[0003] A single battery cell typically includes an electrode assembly, which includes a positive electrode, a negative electrode, and a separator interposed between the positive and negative electrodes. A solid or liquid electrolyte allows ions to move during charging and discharging of the battery cell. The electrode assembly is housed in a casing, and electrode terminals located on the outside of the casing establish an electrically conductive connection with the electrodes. The casing can be cylindrical or rectangular in shape, for example.

[0004] A battery module includes a plurality of battery cells connected in series or in parallel. For example, a battery module may be formed by interconnecting electrode terminals of a plurality of battery cells with one another in an arrangement or configuration to provide a desired amount of power and realize a high-power rechargeable battery.

[0005] Battery modules can be constructed in either a block or modular design. In a block design, each battery cell is connected to 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 a submodule, and several submodules are connected together to form a battery module. In automotive applications, battery systems typically include multiple battery modules connected in series to provide the desired voltage.

[0006] A battery pack is a group of any number of (usually identical) battery modules or individual battery cells. The battery modules and individual battery cells can be configured in series, parallel, or a mixture of both to provide the 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 modules.

[0007] The exothermic decomposition of cell components can lead to so-called thermal runaway. Generally, thermal runaway refers to a process accelerated by a temperature increase that releases energy, causing the temperature to rise further. Thermal runaway occurs when the temperature increase alters the cell conditions in a way that causes a further temperature increase, often with destructive consequences. In rechargeable battery systems, thermal runaway is associated with a strongly exothermic reaction accelerated by the temperature increase. During thermal runaway, the temperature of the battery cell rises very rapidly, and the stored energy is released very suddenly. In extreme cases, thermal runaway can cause the battery cell to explode and catch fire. In milder cases, it can cause irreparable damage to the battery cell.

[0008] When a battery cell is heated above a critical temperature (typically above approximately 150°C), it may enter thermal runaway. Typically, temperatures outside the safe zone on either the low or high side can cause irreversible damage to the battery cell and, therefore, may trigger thermal runaway. Thermal runaway can also occur due to internal or external short circuits in the battery or poor battery maintenance. For example, overcharging or rapid charging can cause thermal runaway.

[0009] During thermal runaway, a failed battery cell can reach temperatures exceeding approximately 700°C. Furthermore, large quantities of hot gases are ejected from the interior of the failed battery cell into the battery pack through exhaust ports in the cell housing. The main components of the exhausted gases are H2, CO2, CO, electrolyte vapor, and other hydrocarbons. Therefore, the exhausted gases are flammable and potentially toxic. The exhausted gases also cause the gas pressure inside the battery pack to increase. In the worst case, the high temperatures cause the process to spread to adjacent battery cells and ignite a fire in the battery pack. At this stage, the fire is difficult to extinguish. Summary of the Invention

[0010] The present disclosure is defined by the appended claims and their equivalents. The following description is subject to this limitation. Any disclosure outside the scope of the claims and their equivalents is intended for illustrative and comparative purposes.

[0011] According to one embodiment of the present disclosure, a battery pack includes: a battery cell stack including a plurality of battery cells; and a separator between two adjacent battery cells among the plurality of battery cells in the battery cell stack. The battery pack also includes a cooler at a bottom side of the battery cell stack, the bottom side of the battery cell stack being opposite to an exhaust side of the battery cell stack. The separator includes a thermally insulating core and a thermally conductive structure, the thermally conductive structure being arranged at a side surface of the separator, the side surface of the separator facing a side surface of one of the plurality of battery cells. The thermally conductive structure includes a central element and a trajectory, the central element being centrally arranged in the side surface of the separator, the trajectory extending from the central element to a peripheral region of the side surface of the separator.

[0012] According to another embodiment of the present disclosure, a battery system includes the battery pack described above.

[0013] According to another embodiment of the present disclosure, a separator for a battery pack includes a thermally insulating core and a thermally conductive structure disposed on a side surface of the separator. The thermally conductive structure includes a central element disposed at an upper portion of the side surface of the separator and a track extending from the central element to a peripheral region of the separator.

[0014] According to another embodiment of the present disclosure, a method for transferring heat within a battery system includes: providing a battery system as described above; separating battery cells of a battery cell stack from each other by positioning a separator between two adjacent battery cells of a plurality of battery cells such that a first side surface of the separator contacts a first side surface of a first battery cell of the two adjacent battery cells and a second side surface of the separator opposite the first side surface of the separator contacts a second side surface of a second battery cell of the two adjacent battery cells of the battery cell stack; and transferring heat from a heated battery cell of the battery cell stack via the separator. The heat is transferred from a hot spot of the heated battery cell to a peripheral area of ​​the separator so as not to exceed a critical temperature that could cause thermal runaway of the battery cell adjacent to the separator. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] 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:

[0016] Figure 1 is a schematic cross-sectional view of a battery system according to an embodiment of the present disclosure.

[0017] Figure 2 is a perspective view of a spacer according to an embodiment of the present disclosure.

[0018] Figure 3 is a perspective view of a spacer according to another embodiment of the present disclosure.

[0019] Figure 4 is a top view of a separator according to another embodiment of the present disclosure.

[0020] Figure 5 is a flow chart describing a process for transferring heat from heated battery cells within a battery pack, according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0021] Reference will now be made in detail to embodiments, examples of which are shown in the accompanying drawings. Aspects and features of the present disclosure and methods for implementing the same will be described with reference to the embodiments shown in 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 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.

[0022] 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.

[0023] 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 can be directly on, directly connected to, or coupled to the other element or layer, or one or more intervening elements or layers may be present. When an element or layer is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another element or layer, there are no intervening elements or layers present. 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.

[0024] In the drawings, for clarity of illustration, the sizes of various elements, layers, etc. may be exaggerated. The same reference numerals represent the same elements. As used herein, the term "and / or" includes any and all combinations of one or more related listed items. In addition, the use of "may" when describing the embodiments of the present disclosure relates to "one or more embodiments of the present disclosure." Expressions such as "at least one of..." and "any of...", when following a list of elements, modify the entire list of elements without modifying the individual elements in the 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 of a, b, and c, or variations thereof. As used herein, the terms "use," "use...", and "being used" may be considered to be synonymous with the terms "utilize," "utilize...", and "being utilized," respectively. As used herein, the terms "substantially," "about," and similar terms are used as approximate terms rather than as terms of degree, and are intended to illustrate the inherent variations in measurements or calculated values ​​that a person of ordinary skill in the art would recognize.

[0025] 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 parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Therefore, a first element, component, region, layer, or part discussed below may be referred to as a second element, component, region, layer, or part without departing from the teachings of the example embodiments.

[0026] For ease of description, spatial relational terms such as "under," "beneath," "below," "above," "on," etc. may be used herein to describe the relationship of one element or feature to another element or feature as shown in the figures. It will be understood that the spatial relational terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if the device in the figures is turned over, an element described as "under" or "beneath" another element or feature will be oriented "above" or "above" the other element or feature. Thus, the term "under" can encompass both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relational descriptors used herein should be interpreted accordingly.

[0027] 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 form "a" and "an" are intended to also include the plural form, unless the context clearly indicates otherwise. It will be further understood that the terms "comprise," "comprising," "including," and / or "comprising" when used in this specification specify the presence of stated features, integers, steps, operations, elements, and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, and / or groups thereof.

[0028] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will also be 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 expressly defined as such herein.

[0029] According to one embodiment of the present disclosure, a battery pack includes a battery cell stack including a plurality of battery cells and at least one spacer positioned between two adjacent battery cells in the battery cell stack. The battery pack includes a cooler positioned at a bottom side of the battery cell stack, with an exhaust side opposite the bottom side of the battery cell stack. The spacer includes a thermally insulating core and at least one thermally conductive structure disposed on or near a side surface of the spacer, the side surface of the spacer facing the side surfaces of the battery cells. The thermally conductive structure includes a central element disposed in the side surface of the spacer and a track (or protrusion) extending from the central element to a peripheral region of the side surface of the spacer.

[0030] Embodiments of the present disclosure are directed to a battery pack comprising a plurality of battery cells and at least one separator. In some embodiments, for example, the separators are arranged alternately with the battery cells within the battery pack. The battery pack includes a cooler connected to (or arranged at) a cooling side of the battery pack and an exhaust vent on an exhaust side of the battery pack opposite the cooling side. Separators are arranged between adjacent battery cells to thermally isolate the cells and prevent thermal runaway of the battery pack. Each of the plurality of separators includes a thermally insulating core and at least one heat-conducting structure. The heat-conducting structure is arranged on a side surface of the separator (the side surface of the separator facing the side surface of the battery cell) to transfer heat from the battery cell. The heat-conducting structure is configured to transfer heat to a peripheral region of the separator and, therefore, may be referred to as a heat transfer structure. The heat-conducting structure includes a central element or central point / region and rails (e.g., arms, rays, or protrusions) extending from the central element to a peripheral region of the separator to transfer heat generated by an affected battery cell to the peripheral region of the separator, thereby reducing heating of adjacent battery cells and preventing thermal runaway of the battery pack.

[0031] A spacer is an element that separates and thermally isolates two adjacent battery cells from each other, thereby reducing or minimizing heat transfer between the two adjacent battery cells. A heat-conductive structure is a structure made of a material with a relatively high thermal conductivity and may include, for example, silver, copper, aluminum, iron, or other metals.

[0032] A thermally insulating core is a core made of a material having a relatively very low thermal conductivity and may comprise, for example, a polymer material, foam or other insulating material.

[0033] A cooler is a structure designed to direct a cooling fluid (such as water) to (or around) the housing of a battery cell to cool the battery cell and transfer heat from the battery cell to other areas of the battery system. The vent side is the side of the battery cell from which pressure can be released if the pressure inside the battery cell increases beyond a certain threshold (beyond which further pressure increase would cause dangerous deformation of the battery cell).

[0034] "The heat-conductive structure is on a side surface of the separator" means that when the separator is inserted into the battery cell stack (i.e., in the assembled state of the battery cell stack or battery pack), the heat-conductive structure is in direct contact with the side surface of the battery cell. "The heat-conductive structure is proximate to the side surface" means that the heat-conductive structure may be fully or partially embedded in the thermally insulating material of the separator's core. In some embodiments, to the extent that the side surface of the heat-conductive structure embedded in the separator is separated from the side surface of the separator closest thereto, the ratio of the distance between the side surface of the heat-conductive structure and the side surface of the separator to the total thickness of the separator is at most approximately 10%, and in some embodiments, at most approximately 5%.

[0035] For example, in the event of a battery cell failure, the heat-conducting structure of the insulator conducts heat from the heated battery cell, thereby reducing or minimizing the thermal impact on the battery cells immediately adjacent to the heated battery cell. This prevents thermal runaway of the entire battery cell stack and a chain reaction that could cause the battery system to burn out. Thermal runaway can be prevented by transferring heat to an area of ​​the insulator that is not directly adjacent to the hot spot at the side surface of the affected battery cell, so that only the heated battery cell that has experienced the failure is affected. This not only improves the safety of the battery cells, but also makes it possible and cost-effective to repair the battery system by simply replacing one affected battery cell. Compared to standard metal plates, the tracks allow for weight reduction, which can reduce the weight of the insulator. In addition, the tracks allow heat to be conducted to areas of the insulator and battery pack where heat can be better and most easily dissipated, thereby reducing the risk of thermal runaway. In addition, the thermal capacity of the heat-conducting element can be reduced compared to metal plates, allowing the structure to heat and cool faster.

[0036] According to an embodiment of the present disclosure, a separator includes two heat-conducting structures disposed on opposite side surfaces of the separator (e.g., on or near opposite side surfaces of the separator). For example, one of the two heat-conducting structures may be disposed on a first side surface of the separator facing a first battery cell among two adjacent battery cells, and the other of the two heat-conducting structures may be disposed on a second side surface of the separator facing a second battery cell among the two adjacent battery cells. These two heat-conducting structures allow the separator to heat more evenly and better transfer heat to the peripheral areas of the separator, regardless of which of the two adjacent battery cells contacting the separator is heated, thereby interrupting thermal runaway in two ways.

[0037] In an embodiment, the heat-conducting structure is spaced from the exhaust side by at least about 10% of the distance from the cooling side to the exhaust side (e.g., separated from the exhaust side). This allows for better heat transfer from the hot spot of the failed battery cell, thereby reducing or minimizing heat transfer to adjacent battery cells via the insulator. Insulators without heat-conducting structures can only slow heat transfer. According to embodiments of the present disclosure, the heat-conducting structure can transfer heat from the hot spot to cooler areas of the insulator, resulting in more uniform heating of the insulator and less heat transfer to adjacent battery cells.

[0038] According to embodiments of the present disclosure, the thermally conductive structure has a thermal conductivity that is at least about one hundred times greater than that of the thermally insulating core, and in some embodiments, at least about five hundred times greater or at least about one thousand times greater than that of the thermally insulating core. The higher thermal conductivity of the thermally conductive structure results in more uniform heating of the insulator and better heat transfer to the peripheral areas of the insulator, allowing more heat to be transferred to the cooler and further preventing heating of adjacent battery cells.

[0039] In embodiments, a heat-conducting structure is made of or includes metal (e.g., a metal composite) and is used to distribute heat within the separator. While the separator core can be made of a material with relatively low thermal conductivity (such as a polymer), a heat-conducting structure made of metal has significantly higher thermal conductivity than plastic components, allowing heat to be better conducted to the edge regions of the separator and achieving more uniform heating of the separator. This prevents or at least reduces the risk of hot spots in the separator and spillage into adjacent battery cells.

[0040] The metal may be, for example, aluminum or copper. Aluminum and copper not only have relatively high thermal conductivity, but can also be easily processed and shaped to form thermally conductive components.

[0041] According to an embodiment of the present disclosure, the heat-conducting structure is a stamped or finely blanked metal sheet of a relatively high thermal conductivity material, or includes such a stamped sheet. The stamped metal sheet on the surface of the separator or embedded in the edge area of ​​the separator can transfer heat from the hot spots of the affected battery cells that contact the separator, thereby resulting in uniform heating of the separator.

[0042] According to another embodiment of the present disclosure, a heat-conducting structure includes a highly thermally conductive central element and highly thermally conductive tracks extending from the central element into the peripheral region of the insulator. A first set of tracks extends from the central element into the upper peripheral region of the insulator, and a second set of tracks extends from the central element into the lower peripheral region of the insulator. This component can reduce weight and the heat capacity of the heat-conducting structure, allowing the insulator to be heated more evenly and heat to be transferred from hot spots at the side surfaces of the battery cells, making adjacent batteries less susceptible to such hot spots. Furthermore, this component can be easily produced as a stamped part. The tracks can define heat distribution leads and transfer heat along the tracks.

[0043] In an embodiment of the present disclosure, the heat transfer structure has a star-shaped configuration, comprising a center (e.g., a central element) and multiple paths extending from the center to the periphery of the separator. The paths are spaced at equal (or equidistant) distances from one another. The star-shaped paths facilitate heat transfer from the center of the separator to the periphery. This allows for uniform heating of the separator, preventing adjacent battery cells from exceeding the critical temperature for thermal runaway of the battery cell stack.

[0044] In another embodiment of the present disclosure, the heat-conducting structure has a spider web structure, in which tracks extend from a central element into the peripheral region of the insulator, and additional circular structures connect the tracks (or extend between the tracks), thereby allowing additional heat to be transferred along the circular structure. For example, the spider web structure includes a center and multiple protrusions / arms / rays extending from the center into the peripheral region of the insulator, and also includes multiple circles surrounding (or extending around) the center and connecting the protrusions / arms / rays extending from the center to the peripheral region of the insulator. The spider web structure allows heat to be dissipated evenly throughout the insulator from the center. This prevents localized overheating of the insulator due to punctual (or localized) heat input from defective battery cells (particularly from hot spots at the side surfaces of the affected battery cells).

[0045] According to an embodiment of the present disclosure, the heat-conducting structure is embedded within the thermal insulation material of the thermal insulation core. This embedding of the heat-conducting structure prevents damage to the heat-conducting structure during assembly of the battery cell stack and prevents breakage or bending of the spacer tracks when installing the spacer in the battery pack. Furthermore, the spacer can be manufactured using a simple injection molding process, where the heat-conducting structure is surrounded by the spacer core and thus secured in the desired position.

[0046] In an embodiment of the battery pack, the battery cells are prismatic cells. Prismatic cells can be easily assembled into parallel stacks, allowing heat to be transferred from the prismatic cells via the separators. Separators can also be used for rounded cells with corresponding designs, so that adjacent cells are separated from each other by separators to prevent thermal runaway of the battery pack.

[0047] According to another embodiment of the present disclosure, a battery system includes a battery pack including a housing and a plurality of battery cells and separators alternately arranged within the housing to form a battery cell stack. The battery system also includes a cooler connected to a cooling side at the bottom of the battery cell stack (or arranged adjacent to the cooling side), and an exhaust side opposite to the cooling side of the battery cell stack. The separator includes a thermally insulating core and at least one heat-conducting structure arranged at (e.g., on or near) a side surface of the separator, the side surface of the separator facing the side surface of the battery cell. The heat-conducting structure includes a central element arranged in an upper half of the side surface of the separator and a track extending from the central element to a peripheral area of ​​the side surface of the separator. In one embodiment, the track extends further toward the cooling side of the battery pack than toward the exhaust side, that is, the track is closer to the cooling side than to the exhaust side.

[0048] In the event of a battery cell failure, for example, the spacer conducts heat away from the heated battery cell, thereby reducing or minimizing the thermal shock to the heated battery cell's immediate neighbors. This prevents the entire battery pack from experiencing thermal runaway and a chain reaction that could potentially destroy the battery system. This thermal runaway can be prevented when heat is transferred to areas of the spacer that are not directly adjacent to the heated hot spot of the heated battery cell, so that only the failed heated battery cell is affected. This not only improves battery cell safety but also allows for cost-effective repairs to the battery system by simply replacing a single affected battery cell.

[0049] According to another embodiment of the present disclosure, an insulator for a battery pack includes a thermally insulating core and at least one heat-conducting structure arranged at a side surface of the insulator (e.g., on or near a side surface of the insulator). The heat-conducting structure includes a central element centrally arranged in an upper half of the side surface of the insulator and a track extending from the central element into a peripheral area of ​​the insulator. According to an embodiment of the present disclosure, the insulator allows for a more uniform heat distribution within the insulator and allows heat to dissipate from hot spots of affected battery cells. This reduces the risk of thermal runaway because the affected battery cells are heated more evenly and prevents point-like (or localized) heat pockets that could otherwise cause thermal damage to adjacent battery cells or thermal runaway of the battery pack.

[0050] According to an embodiment of the present disclosure, the insulator includes two heat-conducting structures, which are arranged on opposite side surfaces of the insulator or embedded in the thermal insulation material of the core near the opposite surfaces of the insulator. When the insulator is in contact with the side surfaces of the battery cells, the heat-conducting structures on the side surfaces of the insulator provide improved heat distribution. The partially or fully embedded heat-conducting structures reduce the risk of damaging one or more of the tracks when the insulator is inserted into the battery pack. The heat-conducting tracks transfer heat from the central element to the periphery of the insulator. Therefore, uniform heating of the insulator can be achieved, preventing the affected battery cells from heating above a critical temperature (above which thermal runaway of the battery cell stack will occur).

[0051] According to another embodiment of the present disclosure, a method for transferring heat within a battery pack includes: providing a battery system as described above; separating battery cells of a battery cell stack from each other by positioning a separator between two adjacent battery cells in the battery cells, wherein a first side surface of the separator contacts a first side surface of the first battery cell, and a second side surface of the separator opposite the first side surface of the separator contacts a second side surface of a second battery cell in the battery cell stack; and transferring heat from the heated battery cells of the battery cell stack via the separator. The heat is transferred from the hot spot of the battery cell to a peripheral area of ​​the separator so as not to exceed a critical temperature that would cause thermal runaway of the battery cell adjacent to the separator.

[0052] A first side surface of the first battery cell is opposite to a second side surface of the second battery cell such that the spacer contacts and thermally separates the first side surface of the first battery cell and the second side surface of the second battery cell.

[0053] Figure 1is a schematic cross-sectional view of a battery system 100 according to an embodiment of the present disclosure. The battery system 100 includes a battery pack 10 including a housing 50 that houses a plurality of battery cells 12, 16 and at least one separator 20 disposed between two adjacent ones of the battery cells 12, 16. In the illustrated embodiment, the battery cells 12, 16 and separators 20 are arranged alternately to form a battery cell stack 14 within the housing 50. The battery pack 10 also includes a cooler 44 connected to (or disposed at) a cooling side 40 of the battery pack 10. In the depicted embodiment, the cooling side 40 is the bottom side of the battery pack 10. Each of the battery cells 12, 16 includes a vent valve 18 that is oriented away from (or facing away from) the cooling side 40 and toward a vent side 42 of the battery pack 10 that is opposite the cooling side 40. The vent valve 18 is positioned at (or in) a cover plate (e.g., a cap plate) 64 that seals a shell surrounding the battery cells 12, 16 (e.g., forming an exterior structure of the battery cells 12, 16). The cooler 44 includes a cooling plate 56 that is configured to allow coolant to flow therethrough to dissipate heat from the battery cells 12, 16 of the battery cell stack 14. The battery cell stack 14 is disposed on the cooling plate 56. The spacer 20 includes a thermally insulating core 22 made of a material having a relatively low thermal conductivity, such as a polymer or a rigid foam. Two heat-conductive structures 24, 26 are disposed on or near opposing side surfaces 32, 34 of each spacer 20. The first side surface 32 of the spacer 20 faces the first side surface 52 of the first battery cell 12 , and the second side surface 34 of the spacer 20 (opposite the first side surface 32 of the spacer 20 ) faces the second side surface 54 of the second battery cell 16 (opposite the first side surface 52 of the first battery cell 12 ).

[0054] Figure 2 is a perspective view of an embodiment of a separator 20 for use with a battery pack 10. The separator 20 has a thermally insulating core 22 and two thermally conductive structures 24, 26 disposed on or near opposing side surfaces 32, 34 of the separator 20. Figure 2In the embodiment shown in , the heat conducting structures 24, 26 are provided on the side surfaces 32, 34, respectively. The heat conducting structures 24, 26 include a high thermal conductivity central element (also referred to as a "central element") 28 that covers (or is aligned with) an expected thermal hotspot of the battery cell 12 when the battery cell 12 becomes hot due to, for example, a fault. There are a plurality of tracks (or protrusions) 30 that extend from the high thermal conductivity central element 28 to the peripheral area of ​​the insulator 20 to improve heat transfer and achieve a more uniform heat distribution throughout the insulator 20. Therefore, the heat conducting structures 24, 26 can be designed as a radial structure 45. The central element 28 and the tracks 30 are made of a high thermal conductivity material, such as copper or aluminum. As Figure 2 As shown in FIG, the heat-conducting structures 24, 26 include six rails 30 extending from a highly thermally conductive central element 28 to a lower peripheral region of the spacer 20 to transfer heat to the cool side of the battery pack 10. Some rails 30 may have a first portion 60 extending from the highly thermally conductive central element 28 and a second portion 62 extending at an angle relative to the first portion 60 to provide more uniform coverage of the side surfaces 32, 34 of the spacer 20. The heat-conducting structures 24, 26 may further include another set of rails 30 extending from the central element 28 to an upper peripheral region of the spacer 20 to further improve (e.g., further equalize) the heat distribution on the side surfaces of the spacer 20. The heat-conducting structures 24, 26 can be easily and inexpensively produced, for example, as stamped or fine-blanked parts. In another embodiment, the heat-conducting structures 24, 26 may be designed as a star-shaped structure, wherein the rails 30 extend from the central element 28 to a peripheral region of the spacer 20, with the same distance between adjacent rails 30.

[0055] Figure 3A separator 20 according to another embodiment of the present disclosure is shown. Separator 20 has a thermally insulating core 22 and two heat-conducting structures 24, 26 arranged on or near opposing side surfaces 32, 34 of separator 20. Heat-conducting structures 24, 26 are designed as a spider web structure 46, with a highly thermally conductive central element 28 covering (or aligned with) anticipated hot spots in battery cells 12, which may occur when a battery cell 12 heats up, for example, due to a fault. Spider web structure 46 includes a plurality of rails 30 extending from central element 28 to a peripheral region of separator 20 and circular structures 58 connecting rails 30 (e.g., extending between rails 30), allowing heat to be conducted along circular structures 58. Central element 28, circular structures 58, and rails 30 are made of a highly thermally conductive material, such as copper or aluminum. Heat-conducting structures 24, 26 can be easily and inexpensively produced, for example, as stamped or fine-blanked parts. The spider web structure 46 allows for improved heat transfer on the side surfaces 32 , 34 of the spacer 20 to achieve a more uniform heat distribution in (or across) the spacer 20 .

[0056] Figure 4 FIG2 is a cross-sectional view of an insulator 20 according to another embodiment. Insulator 20 includes a thermally insulating core 22 and two thermally conductive structures 24, 26, embedded within the thermally insulating core 22 and formed from a highly thermally conductive material (such as copper or aluminum). Thermally conductive structures 24, 26 are formed as stamped metal sheets 36 that are partially or completely embedded within the thermally insulating core 22 of insulator 20. Thermally conductive structures 24, 26 can be designed as described above and in a radial, star, spider-web, or other suitable configuration. The distance from first side surface 32 to first thermally conductive structure 24 (specifically, the surface of first thermally conductive structure 24 embedded within insulator 20) is between approximately 1% and approximately 10% of the total thickness of insulator 20, and in some embodiments, between approximately 2% and approximately 5% of the total thickness of insulator 20. The distance from the second side surface 34 to the second heat-conducting structure 26 (specifically, the surface of the second heat-conducting structure 26 embedded in the spacer 20) is within a range of between about 1% and about 10% of the total thickness of the spacer 20, and in some embodiments, between about 2% and about 5% of the total thickness of the spacer 20. The gap between the first heat-conducting structure 24 and the second heat-conducting structure 26 is greater than about 80% of the total thickness of the spacer 20.

[0057] Figure 5This flowchart, according to an embodiment of the present disclosure, describes a process for transferring heat from a battery cell 12 that has become heated, for example, due to a fault. A heated battery cell 12 is one whose temperature is significantly above its normal operating temperature or in which thermal runaway has occurred. In a first step 200 , a battery pack 10 as described above is provided. In a second step 210 , the battery cells 12 and 16 of a battery cell stack 14 are separated from one another by positioning a separator 20 between a first battery cell 12 and a second battery cell 16 such that a first side surface 32 of the separator 20 contacts a first side surface 52 of the first battery cell 12 and a second side surface 34 of the separator 20, opposite the first side surface 32, contacts a second side surface 54 of the second battery cell 16 of the battery cell stack. In a third step 220 , heat from the heated (or hot) battery cell 12 of the battery cell stack 14 is transferred via the separator 20. In more detail, heat is transferred from the hot spots on the side surfaces 52, 54 of the affected battery cell 12 to the central element 28 of the spacer 20 and then to the peripheral areas of the spacer 20 so that a critical temperature is not exceeded that could cause thermal runaway of the battery cells 16 adjacent to the heated battery cell 12.

[0058] Some reference numbers

[0059] 10 battery pack 12 first battery cell

[0060] 14 Battery cell stack 16 Second battery cell

[0061] 18 Exhaust valve

[0062] 20 Insulation 22 Thermal insulation core

[0063] 24. First heat conduction structure

[0064] 26. Second heat conduction structure

[0065] 28 center element

[0066] 30 track line 32 first side surface

[0067] 34 Second side surface 36 Stamping metal plate

[0068] 40 Cooling side / bottom side 42 Exhaust side

[0069] 44 Cooler 45 Radial structure

[0070] 46 Spider Web Structure

[0071] 50 shell

[0072] 52 First side surface of battery cell

[0073] 54 Second side surface of the battery cell

[0074] 56 Cooling plate 58 Circular structure

[0075] 60 Part 1 62 Part 2

[0076] 64 Cover Plate

[0077] 100 battery system

Claims

1. A battery pack comprising: a battery cell stack comprising a plurality of battery cells and a separator between two adjacent battery cells among the plurality of battery cells; as well as a cooler at a bottom side of the battery cell stack, the bottom side of the battery cell stack being opposite an exhaust side of the battery cell stack, wherein the spacer includes a heat insulating core and a heat conducting structure, the heat conducting structure being at a side surface of the spacer, the side surface of the spacer facing a side surface of one of the plurality of battery cells, The heat conducting structure comprises a central element and tracks, the central element being centrally arranged in the side surface of the spacer, the tracks extending from the central element to a peripheral region of the side surface of the spacer. 2 . The battery pack according to claim 1 , wherein the heat-conducting structure comprises two heat-conducting structures respectively arranged at opposite side surfaces of the spacer. 3 . The battery pack of claim 1 , wherein the thermally conductive structure has a thermal conductivity at least one hundred times greater than a thermal conductivity of the thermally insulating core. The battery pack according to claim 1 , wherein the heat conductive structure is made of metal. The battery pack according to claim 4 , wherein the metal is aluminum or copper.

6. The battery pack of claim 1, wherein the thermally conductive structure comprises a stamped metal plate of a high thermal conductivity material.

7. The battery pack of claim 1 , wherein the rail comprises: a first set of trajectories extending from the central element into an upper peripheral region of the spacer; as well as a second set of trajectories extending from the central element to a lower peripheral region of the spacer, The central element and the rails are made of a material having a relatively high thermal conductivity. The battery pack according to claim 1 , wherein the heat conductive structure has a radial structure.

9. The battery pack according to claim 1, wherein the heat conducting structure has a star-shaped structure, The trajectories extend from the central element into the peripheral region of the spacer and have the same distance between adjacent ones of the trajectories.

10. The battery pack according to claim 1, wherein the heat conducting structure has a spider web structure, The spider web structure includes the trajectories extending from the central element into the peripheral region of the spacer and circular structures connecting adjacent ones of the trajectories.

11. The battery pack of claim 1 , wherein the thermally conductive structure is embedded in the thermally insulating core.

12. The battery pack of claim 1, wherein the battery cell is a prismatic battery cell.

13. A battery system comprising the battery pack according to any one of claims 1 to 12.

14. A method for transferring heat within a battery pack according to any one of claims 1 to 12, the method comprising transferring heat from a heated battery cell in the battery cell stack via the spacer from a hot spot of the heated battery cell to the peripheral region of the spacer.

Images