Battery system and vehicle including the same

Abstract

The invention relates to a battery system and a vehicle including the same. The battery system includes: a plurality of battery cells arranged along an alignment axis; and a cell separator in a gap between adjacent ones of the battery cells, the cell separator including a central portion and a boundary portion adjoining the central portion, the central portion having a greater thickness than the adjoining boundary portion, wherein opposite outer surfaces of the cell spacer are arranged at the same distance but in opposite directions from a central plane perpendicular to the alignment axis and extending through the central portion and the boundary portion.

Description

Technical Field

[0001] Aspects of the present disclosure relate to a battery system and a vehicle including the 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 cars that are propelled by an electric motor using energy stored in a rechargeable battery. Electric vehicles may be powered solely by batteries, such as in a battery electric vehicle (BEV), or may include a combination of an electric motor and, for example, a conventional internal combustion engine, such as in a plug-in hybrid electric vehicle (PHEV). BEVs and PHEVs use high-capacity rechargeable batteries designed to provide power for propulsion for sustained periods of time.

[0003] A single battery cell includes an electrode assembly, which includes a positive electrode, a negative electrode, and a separator interposed between the electrodes. A solid or liquid electrolyte allows ions to move during charging and discharging of the battery cell. The electrode assembly is located in a casing, and electrode terminals located outside 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 is formed by connecting a plurality of battery cells in series and / or in parallel. That is, a battery module is formed by interconnecting electrode terminals of a plurality of battery cells according to a desired amount of power in order to realize a high-power rechargeable battery.

[0005] Battery modules can be constructed in a block or modular design. In a block design, each battery is coupled 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 battery modules (e.g., identical battery modules) or individual battery cells. The battery modules or battery cells can be configured in series, parallel, or a mixture of the two to deliver the desired voltage, capacity, or power density. The components of a battery pack include the individual battery modules and the interconnections that provide electrical conductivity between them.

[0007] To ensure proper thermal control of the battery pack, a thermal management system can be utilized to safely utilize at least one battery module by effectively emitting, discharging, and / or dissipating heat generated from its rechargeable batteries. If heat dissipation / dissipation / heat dissipation is not adequately performed, temperature deviations can occur between different battery cells, potentially resulting in the battery module failing to generate the desired amount of power. Furthermore, an increase in internal temperature can cause abnormal reactions within the battery, degrading the charging and discharging performance of the rechargeable battery and shortening the life of the rechargeable battery. Therefore, cell cooling for effectively dissipating / discharging / heat dissipation from the cells is desirable.

[0008] The exothermic decomposition of a cell assembly can lead to so-called thermal runaway. In general, thermal runaway describes a process that is accelerated by increased temperature, which in turn releases energy that further increases the temperature. Thermal runaway occurs when an increase in temperature changes conditions in a way that causes a further increase in temperature, usually with destructive consequences. In rechargeable battery systems, thermal runaway is associated with a strongly exothermic reaction that is accelerated by an increase in temperature. In thermal runaway, the temperature of a battery cell rises incredibly quickly and the stored energy is released very suddenly. In extreme cases, thermal runaway can cause the battery cell to explode and start a fire. In other cases, it can result in the battery cell being damaged beyond repair.

[0009] When a battery cell is heated above a critical temperature (e.g., above 150°C), it can transition to a thermal runaway state. Typically, temperatures outside the safety zone on the low or high side can cause irreversible damage to the battery and, therefore, can trigger thermal runaway. Thermal runaway can also occur due to an internal or external short circuit in the battery or poor battery maintenance. For example, overcharging or rapid charging can cause thermal runaway.

[0010] During thermal runaway, a failed battery cell can reach temperatures exceeding 700°C. Furthermore, large amounts of hot gases are ejected from the interior of the failed battery cell through the exhaust openings of the cell housing into the battery pack. 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 within the battery pack to increase. In the worst case, the high temperature causes the process to spread to adjacent cells and cause a fire in the battery pack. At this stage, the fire may be difficult to extinguish.

[0011] A battery system may include multiple battery cells separated from each other by cell spacers. Such cell spacers are used to limit heat transfer between adjacent battery cells, particularly between a faulty battery cell and a healthy battery cell, such as during thermal runaway. In the related art, cell spacers are designed with a simple, uniform shape, particularly a cuboid with a rectangular or substantially rectangular cross-section, similar to the shape of a battery cell.

[0012] During their lifetime, the battery cells of a battery system are charged and discharged many times, wherein the battery cells expand during charging, i.e. increase in thickness and therefore increase in volume, and contract during discharging, i.e. decrease in thickness and therefore decrease in volume. This periodic volume change is called cell breathing. Due to this cell breathing, the cell spacers deform and their thickness decreases, especially in their middle section, as this is typically where the greatest pressure / force is applied by adjacent battery cells. As the cell spacers become thinner, the distance between adjacent battery cells may decrease, such that they can no longer adequately perform their purpose of limiting heat conduction between adjacent battery cells. Moreover, the structural integrity of the battery system may be compromised, as the cell spacers no longer adequately hold the battery cells in place.

[0013] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art. Summary of the Invention

[0014] Aspects of the disclosed embodiments are directed to overcoming or reducing at least some of the disadvantages of the prior art and providing a battery system in which battery cells are sufficiently thermally isolated from each other during multiple breathing cycles, thereby extending the life of the battery system.

[0015] According to some embodiments of the present disclosure, a battery system is provided, comprising: a plurality of battery cells arranged along an alignment axis; and a cell separator in a gap between adjacent battery cells in the battery cells, the cell separator comprising a central portion and a boundary portion adjacent to the central portion, the central portion having a greater thickness than the adjacent boundary portion, wherein opposite outer surfaces of the cell separator are arranged at the same distance from a central plane but in opposite directions, the central plane being perpendicular to the alignment axis and extending through the central portion and the boundary portion.

[0016] In some embodiments, the cell spacer has a mirror-symmetrical shape.

[0017] In some embodiments, the thickness of the cell spacer decreases continuously from the central portion to each boundary portion.

[0018] In some embodiments, the cell spacer has an oval cross-section.

[0019] In some embodiments, the thickness of the cell spacer decreases in a step-wise manner from the central portion to each boundary portion.

[0020] According to some embodiments of the present disclosure, an electric vehicle including the battery system is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Features will become apparent to those skilled in the art by describing in detail exemplary embodiments with reference to the accompanying drawings, in which:

[0022] Figure 1 is a schematic cross-sectional view of a battery system with a swollen battery cell, according to some examples.

[0023] Figure 2 is a schematic cross-sectional view of a battery system with a deformed cell separator, according to some examples.

[0024] Figure 3 is a schematic perspective view of a cell spacer according to some embodiments of the present disclosure.

[0025] Figure 4 According to some embodiments of the present disclosure, Figure 3 Schematic cross-sectional view of a battery system with cell separators shown in .

[0026] Figure 5 is a schematic cross-sectional view of a battery system having a cell separator according to some other embodiments of the present disclosure.

[0027] Figure 6 is at the end of life stage according to some embodiments of the present disclosure Figure 4 or Figure 5 Schematic cross-sectional view of the battery system shown in . DETAILED DESCRIPTION

[0028] Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. The effects and features of the exemplary embodiments and their implementation methods will be described with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals represent the same elements, and redundant descriptions are omitted. However, the present disclosure can be implemented in various different forms and should not be construed as being limited to the embodiments shown herein. On the contrary, 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.

[0029] 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.In the drawings, the relative sizes of elements, layers, and regions may be exaggerated for clarity.

[0030] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. 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, unless the context clearly indicates otherwise, terms in the singular may include plural forms.

[0031] It should be understood that although the terms "first" and "second" are used to describe various 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 this 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 associated listed items. Expressions such as "at least one of..." modify the entire element list when it is before the element list, rather than modifying the individual elements in the list.

[0032] 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 take into account the inherent variations in measured or calculated values ​​that one of ordinary skill in the art would recognize. Furthermore, if the term "substantially" is used in conjunction with a feature that can be expressed using a numerical value, the term "substantially" means a range of + / - 5% of that value centered around that value.

[0033] It will be further understood that the terms “include,” “comprising,” “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.

[0034] It will also be understood that when a film, region or element is referred to as being “on” or “over” 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.

[0035] In this document, the terms "upper" and "lower" are defined relative to the z-axis. For example, the upper cover is located above the z-axis, while the lower cover is located below it. In the accompanying drawings, the dimensions of elements may be exaggerated for clarity. For example, in the accompanying drawings, the dimensions or thickness of each element may be arbitrarily illustrated for illustrative purposes, and thus the embodiments of the present disclosure should not be construed as limited thereto.

[0036] In the following description of the embodiments of the present disclosure, terms in the singular may include plural forms unless the context clearly indicates otherwise.

[0037] 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, unless expressly defined as such herein, 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 this specification, and should not be interpreted in an idealized or overly formal sense.

[0038] According to some aspects of the present disclosure, a battery system is provided. The battery system includes a plurality of battery cells, such as prismatic battery cells. The battery system may include a housing for accommodating the battery cells. The battery cells within each battery pack may be interconnected via electrical connection devices (e.g., bus bars) that contact the corresponding electrodes / cell terminals of the battery cells. The battery cells are arranged to form one or more battery packs, wherein in the battery pack, the battery cells are electrically interconnected in series and / or in parallel, for example, as described above. A plurality of battery cells within a battery pack may form a battery module. Two or more of the battery modules may be stacked to form a battery stack. The battery cells are preferably prismatic battery cells.

[0039] The battery cells may be arranged along an alignment axis. For example, the battery cells may be stacked along the axis. A cell spacer is arranged between two adjacent / neighboring battery cells. Thus, a cell spacer is provided in each gap between adjacent battery cells. Thus, adjacent battery cells are separated from each other by the cell spacer. The battery system may include a plurality of battery cells and cell spacers, and the battery cells and cell spacers may be arranged or stacked alternately along the alignment direction. The battery system includes at least two battery cells and one cell spacer arranged between the two battery cells. The cell spacer separates or spaces adjacent battery cells from each other. The cell spacer also holds the battery cells in place by keeping them at a set or predetermined distance from each other and limits heat conduction between adjacent battery cells, for example during thermal runaway of one of the battery cells.

[0040] According to some embodiments of the present disclosure, a cell separator includes a center portion and an adjacent boundary portion. The center portion has a greater thickness than the adjacent boundary portion. In other words, the center portion is thicker than the boundary portion. The center portion refers to a portion / section of the cell separator arranged in the middle area of ​​the cell separator, and the center portion transitions to the boundary portion on the side. When the battery system is installed / placed in an electric vehicle, the boundary portion may be composed of an upper boundary portion and a lower boundary portion. The thickness of the cell separator represents the extension of the cell separator along the alignment axis and refers to the distance between two opposing outer surfaces of the cell separator along the alignment axis. The opposing outer surfaces of the cell separator are arranged at the same distance from a center plane in opposite directions, the center plane being perpendicular to the alignment axis and extending through the center portion and the boundary portion in opposite directions. In other words, the cell separator has two opposing outer surfaces of the cell separator, and the two opposing outer surfaces are spaced apart from the center plane by a first distance in opposite directions along the alignment axis, such that the distance between the two opposing outer surfaces is twice the first distance. This distance between the two opposing outer surfaces (i.e., twice the first distance) is the thickness of the cell separator. Therefore, the distance at which the outer surface is arranged from the central plane is greater at the central portion than at the boundary portion.

[0041] During a breathing cycle, battery cells of a battery system may expand and, therefore, exert pressure / force on adjacent cell separators, as described above. Since battery cells typically exert greater force or pressure at their center than at their edges, the center portion of the cell separator according to some embodiments is compressed more than the boundary portions. Since the cell separator according to some embodiments of the present disclosure is thicker at its center portion than at its boundary portions, and since the opposing outer surfaces are the same distance from the center plane, the cell separator more evenly distributes the forces received by adjacent battery cells. Therefore, the cell separator according to some embodiments of the present disclosure can better withstand these forces.

[0042] In addition, although the cell spacers according to some embodiments of the present disclosure may be deformed by the expanded battery cells after a large number of breathing cycles, the cell spacers are deformed into a more suitable shape than known cell spacers. Due to the more evenly distributed force received by the adjacent battery cells, the cell cover can be flattened. That is, the cell spacer is deformed so that the material moves (e.g., is pushed) from the center portion to the boundary portion, so that the thickness difference between the center portion and the boundary portion is at least partially compensated over time. After multiple breathing cycles, the shape of the cell spacers according to some embodiments of the present disclosure can be transformed into a shape that is closer to a cuboid with a rectangular or substantially rectangular cross-section similar to the above-mentioned cell spacers. In this shape, the cell spacers can still perform their intended purpose: as the deformed cell spacer contacts the adjacent battery cells substantially over its entire surface, the battery cells are spaced apart and heat conduction between the battery cells is limited. Compared to known cell spacers, the contact area between the cell spacer and the adjacent battery cells does not decrease over time, but may even expand. Therefore, the cell spacer ensures that the distance between two adjacent / adjacent battery cells is not less than a set or predetermined minimum distance.

[0043] In summary, therefore, battery systems according to some embodiments of the present disclosure allow the cell spacers to fully perform their intended purpose: to separate the battery cells and limit heat conduction between the battery cells, even after multiple breathing cycles. Thus, using the cell spacers of battery systems according to some embodiments of the present disclosure, the battery cells are thermally isolated from each other over multiple breathing cycles. Here, the cell spacers can maintain a stable thermal resistance over the life of the battery system. These cell spacers can even extend the life of the battery system.

[0044] According to some embodiments, the cell separator has a mirror-symmetrical shape. That is, there can be a mirror-symmetrical plane for the cell separator so that the reflection at this plane is a symmetrical operation of the cell separator. In other words, the cell separator can be an object for which each point has a one-to-one mapping to another point equidistant from and on the opposite side of a common plane, which is a mirror-symmetrical plane. The mirror-symmetrical plane is a plane perpendicular to the alignment axis. The mirror-symmetrical plane is a center plane. When the cell separator is mirror-symmetrical, the outer surface of the cell separator is the same amount away from the mirror-symmetrical plane in opposite directions. Therefore, there are at least two outer surfaces of the cell separator that extend the same distance in opposite directions from the center plane (i.e., the mirror-symmetrical plane), which is perpendicular to the alignment axis and extends through the center portion and the boundary portion. Cell separators of this shape are particularly suitable for maintaining sufficient distance between adjacent battery cells, which may be because the external pressure applied by adjacent battery cells is evenly distributed along the surface and interior of the cell separator.

[0045] According to some embodiments, the thickness of the cell separator decreases continuously from the center portion to each boundary portion. As described above, the thickness of the cell separator is the largest at the center portion and is smaller at the boundary portion. Therefore, with reference to an axis perpendicular to the alignment axis, the farther the distance from the center of the cell separator along the perpendicular axis is, the thickness of the cell separator decreases. Continuous reduction can refer to a stable reduction, for example, without steps (for example, discrete steps). In other words, the cell separator becomes thinner continuously toward the opposite end. This results in a particularly stable shape of the cell separator because the force applied by the adjacent battery cells can be particularly evenly distributed on the surface and inside of the cell separator. According to some embodiments, the cell separator has an elliptical cross-section. The elliptical cross-section can be along the alignment direction. In other words, the cell separator can have a biconvex shape. Cell separators of this shape can be particularly stable and easy to manufacture.

[0046] According to some embodiments, the thickness of the cell separator decreases in a step-by-step manner from the center portion to each boundary portion. As described above, the thickness of the cell separator is the largest at the center portion and is smaller at the boundary portion. Therefore, with reference to an axis perpendicular to the alignment axis, the farther the distance from the center of the cell separator along the perpendicular axis is, the thickness of the cell separator decreases. Continuous reduction means gradually decreasing in multiple steps (for example, at least two or at least three steps). Therefore, in contrast to the continuous reduction explained above, the cell separator of this embodiment becomes thinner towards the end in multiple steps. This alternative also results in a particularly stable shape of the cell separator, because the forces exerted by adjacent battery cells can be particularly evenly distributed on the surface and inside of the cell separator.

[0047] The present disclosure also relates to an electric vehicle including the battery system.

[0048] Figure 1 and Figure 2 A battery system 10 according to some examples is shown. The battery system 10 includes a plurality of battery cells 12 and cell separators 14 arranged alternately. The cell separators 14 can provide spaces between adjacent battery cells 12, space the battery cells 12 from each other, and limit heat conduction between the battery cells 12. The cell separators 14 can limit the propagation of heat via conduction between a faulty battery cell (e.g., a battery cell experiencing thermal runaway) and a healthy battery cell. The cell separators 14 have a rectangular parallelepiped shape having a rectangular or substantially rectangular cross-section, such as Figure 1 shown.

[0049] During its lifetime, the battery cell 12 is charged and discharged many times, wherein the battery cell 12 expands during charging, i.e., increases in thickness and thus volume, and contracts during discharging, i.e., decreases in thickness and thus volume. This cyclic volume change is known as cell breathing. Figure 1 A battery cell 12 is shown in the middle of the battery system 10 in a swollen state, with the increase in thickness exaggerated for illustrative purposes. As indicated by the arrows, the swollen battery cell 12 exerts a force on the adjacent cell separator 14 on the opposite side of the swollen battery cell 12. The battery cell 12 generally swells more in the center than at the edges.

[0050] As a result of the expansion of the battery cells 12, the cell separators 14 deform over time, as shown in FIG. Figure 2 As shown, Figure 2 The battery system 10 is shown after multiple breathing cycles. With each breathing cycle, the battery cells 12 compress the cell separator 14, thereby gradually reducing its thickness over time. Because the battery cells 12 expand more in the center than at the edges, the cell separator 14 forms a concave shape with a reduced thickness in the middle, as shown in FIG. Figure 2 These deformed cell spacers 14 are no longer able to adequately perform their intended purpose of spacing the battery cells 12 apart and limiting heat conduction between the battery cells 12 , which can prove detrimental to the structural integrity of the battery system 10 .

[0051] Some embodiments of the present disclosure overcome Figures 3 to 5 This problem is addressed by the battery systems 100 and 100 ′ and the cell separators 14 shown in FIG.

[0052] Figure 3 and Figure 4 A cell separator and a battery system 100 including the cell separator according to some embodiments of the present disclosure are shown. Figure 4 The battery system 100 shown in FIG. 1 includes a plurality of prismatic battery cells 12 arranged along an alignment axis x, with cell separators 14 disposed between adjacent ones of the battery cells 12. In other words, the battery cells 12 and the cell separators 14 are alternately stacked along the alignment axis x. The battery cells 12, while prismatic in their regular state, are shown in their expanded state due to cell breathing, as shown in FIG. Figure 4 shown.

[0053] Figure 3 A perspective view of a cell spacer 14 is schematically shown. Figure 3 and Figure 4, each monomer separator 14 has a mirror-symmetric shape, and the mirror-symmetric plane lies in the y-z plane and centrally cuts through the monomer separator 14. Thus, the mirror-symmetric plane is the central plane 18. Each monomer separator 14 includes a central portion 15, and a lower boundary portion 16a and an upper boundary portion 16b adjacent to the central portion 15. The boundary portion 16 includes the lower boundary portion 16a and the upper boundary portion 16b. The central portion 15 has a thickness w1 greater than the thickness w2 of the adjacent boundary portion 16. The central plane 18 extends along the z-axis through the central portion 15 and the boundary portion 16. In some embodiments, each monomer separator 14 has an elliptical cross-section as Figure 4 shown. The thickness of the monomer separator 14 continuously (e.g., steadily) decreases from the central portion 15 having a thickness w1 (where the thickness w1 is at its maximum 'w'1 when the distance is from point O' to O'') to each boundary portion 16 having a smaller value of thickness w2 (i.e., w2 < w1). The thickness w2 has a minimum value of 0 at the end points A or B. The thickness represents the extension of the monomer separator 14 along the alignment axis x. Since the monomer separator 14 is mirror-symmetric with respect to the central plane 18 (or the y-z plane), the outer surfaces 17a and 17b of the monomer separator 14 are the same amount away from the central plane 18 in opposite directions. Both the outer surfaces 17a and 17b can extend the same distance in opposite directions along the alignment axis x from the mirror-symmetric plane, i.e., a distance of 0.5w1 at the central portion 15. In Figure 3 , for illustrative purposes, the ellipsoidal shape of the monomer separator 14 can be enlarged.

[0054] As described above, Figure 4 the battery cell 12 in Figure 6In this rectangular parallelepiped shape, the cell spacers 14 can still perform their intended purpose: spacing the battery cells 12 apart and limiting heat conduction between the battery cells 12 as the deformed cell spacers 14 contact adjacent battery cells over substantially their entire surfaces. Even in this deformed shape, the cell spacers 14 ensure that a set or predetermined distance between two adjacent / adjacent battery cells 12 is maintained.

[0055] Figure 5 A battery system 100' according to some other embodiments of the present disclosure is shown. The battery system 100' differs from the above-described embodiments in the shape of the cell separator. The battery system 100' includes a plurality of battery cells 12 arranged along an alignment axis x, wherein cell separators 14' are provided between adjacent ones of the battery cells 12. The cell separator 14' is also mirror-symmetrical, with its mirror-symmetrical plane being in the yz plane, i.e., the mirror-symmetrical plane being perpendicular to the x-axis and therefore perpendicular to the alignment axis. In addition, the cell separator 14' includes a central portion 15 and a boundary portion 16 adjacent to the central portion 15. The central portion 15 has a thickness w1 that is greater than a thickness w2 of the adjacent boundary portion 16.

[0056] exist Figure 5 In the embodiment, the cell spacer 14' is not an elliptical shape in which the thickness continuously decreases from the center portion to the boundary portion. Instead, the thickness of the cell spacer 14' decreases in a stepwise manner from the center portion 15 to each boundary portion 16 (for example, gradually decreases in a stepwise manner). Figure 5 As shown, the thickness is greatest at the central portion 15 and decreases in at least one step at the boundary portion 16 .

[0057] Similar to Figure 3-Figure 4 The cell separator of the embodiment, when the battery cell 12 is as Figure 5 When expanded as shown, the cell separator 14' is compressed by the battery cell 12. This stepped shape of the cell separator 14' is also particularly suitable for withstanding the compressive force exerted by the battery cell 12. However, after a plurality of breathing cycles, the result can be the same as that of the cell separator 14 having an elliptical cross section. That is, the cell separator 14' can be flat and can eventually be formed into a rectangular parallelepiped shape with a rectangular or substantially rectangular cross section, such as Figure 6 shown.

[0058] Thus, providing mirror-symmetrical cell spacers 14, 14' that are thicker at their central portions 15 than at their border portions 16 allows the cell spacers 14, 14' to fully perform their intended purpose of spacing the battery cells 12 apart and limiting heat conduction between the battery cells 12, even after multiple breathing cycles.

[0059] It should be understood that the embodiments described herein should be considered illustrative rather than restrictive. Descriptions of features or aspects within each embodiment should generally be considered applicable to other similar features or aspects in other embodiments. Although one or more embodiments have been described with reference to the accompanying drawings, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope defined by the appended claims and their equivalents.

[0060] Some reference numerals

[0061] 10 Known battery systems

[0062] 12 battery cells

[0063] 14,14' monomer spacer

[0064] 15 The center part of the monomer spacer

[0065] 16 The boundary part of the monomer spacer

[0066] 16a lower boundary

[0067] 16b upper boundary

[0068] 17a outer surface

[0069] 17b outer surface

[0070] 100 Battery system according to some embodiments of the present disclosure

[0071] 100′ Battery system according to some embodiments of the present disclosure

Claims

1. A battery system comprising: a plurality of battery cells arranged along an alignment axis; as well as a cell separator positioned in a gap between adjacent battery cells among the battery cells, the cell separator including a central portion and a boundary portion adjacent to the central portion, the central portion having a greater thickness than the boundary portion, Wherein, opposite outer surfaces of the cell spacers are arranged at the same distance from a central plane but in opposite directions, the central plane being perpendicular to the alignment axis and extending through the central portion and the boundary portion.

2. The battery system according to claim 1, wherein: The cell spacer has a mirror-symmetrical shape.

3. The battery system according to claim 1, wherein: The thickness of the cell spacer continuously decreases from the central portion to each of the boundary portions.

4. The battery system according to claim 3, wherein: The cell spacer has an elliptical cross section.

5. The battery system according to claim 1, wherein: The thickness of the cell spacer decreases in a stepwise manner from the central portion to each of the boundary portions.

6. The battery system according to claim 1, wherein: The cell separator is in contact with the adjacent battery cell, The contact area between the cell spacer and the adjacent battery cell does not decrease over time.

7. An electric vehicle comprising the battery system according to any one of claims 1 to 6.

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