Battery cells, battery modules, battery packs including the same, and vehicles

Abstract

The present invention introduces battery cells, battery modules, battery packs containing the same, and vehicles, which are packaged in packaging material comprising an aluminum layer and a polymer layer, wherein the packaging material is characterized in that a graphite layer is disposed in the aluminum layer, the polymer layer, or between the aluminum layer and the polymer layer.

Description

Technical Field

[0001] The present invention relates to a battery cell, a battery module, a battery pack including the same, and a vehicle, which can eliminate thermal imbalance in the battery cell, enable thermal balancing, prevent degradation of the battery cell and improve its performance, and enhance the safety of the battery cell by preventing heat concentration at specific sites.

Background Art

[0002] Recently, technologies for carbon reduction have been actively developed to address environmental issues such as abnormal temperatures. To reduce carbon, energy must be produced in an environmentally friendly way rather than using fossil fuels to produce energy. The produced energy must be stored in the form of electrical energy and used in vehicles, various industrial sites, and households.

[0003] To utilize electrical energy for carbon reduction, the use of a battery that can store and draw out electrical energy is essential. Therefore, ensuring the performance of the battery is essential for storing electrical energy sufficiently and using it conveniently.

[0004] Batteries mainly utilize the redox reaction of metal ions, use metal ions at high density to increase the capacity, charge-discharge performance, and efficiency of the battery, and much research has been done on substances constituting the electrolyte and solid electrolytes. However, generally, there is a problem that the stability of the battery decreases as its performance develops (progresses / evolves).

[0005] Batteries used in vehicles, industry, and homes are manufactured in physical units called battery packs. A battery pack contains numerous battery cells enclosed in a sealed battery case, preventing fire from spreading to the outside in the event of an accident such as battery overheating, and protecting the internal battery cells from degradation due to external environmental factors or physical damage.

[0006] A battery pack contains numerous battery cells in a form intermediate between modules and assemblies (CMAs, Cell module assemblies). In the case of battery modules or assemblies, numerous battery cells are assembled into a single module or assembly, and these modules are fastened together inside the pack case, completing the battery pack. During battery maintenance, maintenance is made easier by performing maintenance on these module or assembly units.

[0007] The numerous unit battery cells that make up a module or assembly consist of a positive electrode, a negative electrode, and an electrolyte. Since battery cells generate heat during charging and discharging, effective heat dissipation is necessary. Furthermore, from the perspective of battery modules, assemblies, and battery packs, efficient heat dissipation design is essential to prevent safety-related accidents.

[0008] On the other hand, batteries can deteriorate due to manufacturing errors, excessive charging and discharging, and aging. If battery deterioration continues, it can eventually lead to a fire. Therefore, it is necessary to take precautions to prevent fires from starting in batteries.

[0009] For this reason, batteries require cooling of the battery modules and assemblies through a cooling system, and overall temperature balancing must be achieved from the perspective of the battery cells that make up the modules and assemblies.

[0010] The matters described above as background technology are for the sole purpose of facilitating understanding of the background of the present invention and should not be interpreted as constituting prior art already known to those with ordinary skill in this field. [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] This invention was proposed to solve these problems and aims to provide a battery cell, a battery module, a battery pack including the same, and a vehicle that can improve the performance and safety of the battery cell by performing thermal balancing of the battery cell.

[0012] The technical problems that this invention aims to solve are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those with ordinary skill in the art to which this invention pertains from the description below. [Means for solving the problem]

[0013] To achieve the aforementioned objective, the battery cell according to the present invention is packaged in a packaging material comprising an aluminum layer and a polymer layer, wherein the graphite layer may be placed in the aluminum layer, in the polymer layer, or between the aluminum layer and the polymer layer.

[0014] The graphite layer of the packaging material may be positioned to be in close contact with the aluminum layer.

[0015] The packaging material may have an aluminum layer on the outside of the polymer layer, and a graphite layer on the outside of the aluminum layer.

[0016] The packaging material may have a graphite layer additionally bonded to the outside, with the polymer layer and aluminum layer molded together as a single unit.

[0017] The packaging material may be positioned so that the graphite layer corresponds to the sides of the battery cell.

[0018] The packaging material may have an insulating layer on the outermost surface.

[0019] The packaging material consists of a polymer layer and an aluminum layer molded together, with an additional graphite layer bonded to the outside. The graphite layer is folded multiple times and bonded to enclose the battery cell, and an insulating layer may be placed on the outside of the graphite layer at a position corresponding to the sides of the battery cell.

[0020] The battery module according to the present invention includes a first battery cell packaged in a packaging material comprising an aluminum layer and a polymer layer, and a second battery cell packaged in a packaging material comprising an aluminum layer and a polymer layer, wherein the packaging material has a graphite layer disposed in the aluminum layer, or in the polymer layer, or between the aluminum layer and the polymer layer, and the first battery cell and the second battery cell may be arranged adjacent to each other.

[0021] A pair of first battery cells may be arranged adjacent to each other between a pair of second battery cells.

[0022] A pair of first battery cells may be arranged adjacent to each other with a graphite sheet in between.

[0023] A compression pad may be placed on the outside of each of the second battery cells.

[0024] A second battery cell may be positioned between a pair of first battery cells.

[0025] A compression pad may be placed on the outside of each of the first battery cells.

[0026] A graphite sheet may be placed between the compression pad and the first battery cell.

[0027] At least one or more first battery cells and at least one or more second battery cells together form a cell bank, and compression pads can be arranged on the outer sides of both sides of the cell bank respectively.

[0028] A graphite sheet can be arranged between the compression pad and the first battery cell adjacent thereto.

[0029] The compression pad may include a heat insulation layer.

[0030] The battery pack and the vehicle according to the present invention may include the battery module described above.

Advantages of the Invention

[0031] According to the battery cell, battery module, battery pack including the same, and vehicle of the present invention, the battery cells included in the module or assembly can perform self-thermal balancing, thereby enhancing the overall thermal management efficiency and improving performance and stability.

[0032] Also, since thermal balancing can be performed by one battery cell, the efficiency of overall thermal management is increased, and performance and stability can be significantly improved while still using the existing cooling system as it is.

[0033] Furthermore, by effectively using the graphite sheets required for performing thermal balancing of each battery cell, the manufacturing cost can be reduced and the assembly man-hours can be significantly reduced.

[0034] The effects obtained by the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those with ordinary knowledge in the technical field to which the present invention pertains from the following description.

Brief Description of the Drawings

[0035] [Figure 1] It is a cross-sectional view of a packaging material for a battery cell according to an embodiment of the present invention. [Figure 2] This figure shows a battery cell according to one embodiment of the present invention. [Figure 3] This is a cross-sectional view of a battery cell packaging material according to yet another embodiment of the present invention. [Figure 4] This figure shows a battery cell according to yet another embodiment of the present invention. [Figure 5] Figure 4 is a cross-sectional view of the battery cell shown. [Figure 6] This is a structural diagram of a battery module according to one embodiment of the present invention. [Figure 7] This is a structural diagram of a battery module according to yet another embodiment of the present invention. [Figure 8] This figure shows a compression pad for a battery module according to one embodiment of the present invention. [Figure 9] Figure 8 is a cross-sectional view of the compression pad. [Figure 10] This figure shows a battery pack and a vehicle to which the battery cells of the present invention are applied. [Modes for carrying out the invention]

[0036] In describing the embodiments disclosed herein, if a specific description of related published technology is deemed to obscure the gist of the embodiments disclosed herein, such detailed description will be omitted. Furthermore, the accompanying drawings are merely for the purpose of facilitating the understanding of the embodiments disclosed herein, and it should be understood that the accompanying drawings do not limit the technical ideas disclosed herein and include all modifications, equivalents, or substitutions that fall within the concept and technical scope of the present invention.

[0037] Terms including ordinal numbers, such as "first," "second," etc., can be used to describe a variety of components, but the components are not limited by such terms. These terms are used solely for the purpose of distinguishing one component from another.

[0038] A singular expression includes plural forms unless the context clearly indicates a different meaning.

[0039] In this specification, terms such as “includes” or “have” are intended to indicate the presence of features, figures, stages, operations, components, parts, or combinations thereof as described in the specification, and should be understood not to preemptively exclude the presence or possibility of adding one or more other features, figures, stages, operations, components, parts, or combinations thereof.

[0040] The suffixes "module" and "unit" used for the components in the following description are added or used interchangeably solely for the sake of ease of specification preparation and do not have any distinct meaning or role in themselves.

[0041] When it is mentioned that one component is "connected" or "linked" to another component, it should be understood that it may be directly connected to or linked to the other component, but it may also be the case that other components exist in between (in the middle). On the other hand, when it is mentioned that one component is "directly connected" or "directly linked" to another component, it must be understood that there are no other components in between.

[0042] Figure 1 is a cross-sectional view of the packaging material for a battery cell according to one embodiment of the present invention; Figure 2 is a drawing showing a battery cell according to one embodiment of the present invention; Figure 3 is a cross-sectional view of the packaging material for a battery cell according to yet another embodiment of the present invention; Figure 4 is a drawing showing a battery cell according to yet another embodiment of the present invention; Figure 5 is a cross-sectional view of the battery cell shown in Figure 4; Figure 6 is a structural diagram of a battery module according to one embodiment of the present invention; Figure 7 is a structural diagram of a battery module according to yet another embodiment of the present invention; Figure 8 is a drawing showing the compression pad of a battery module according to one embodiment of the present invention; Figure 9 is a cross-sectional view of the compression pad in Figure 8; and Figure 10 is a drawing showing a battery pack to which the battery cell of the present invention is applied and a vehicle.

[0043] The embodiments disclosed herein will now be described in detail with reference to the attached drawings. Regardless of the reference numerals used in the drawings, identical or similar components will be given the same reference numerals, and redundant descriptions thereof will be omitted.

[0044] Battery cells heat up during charging and discharging, and such temperature increases induce a decrease in the performance and lifespan of the battery itself. Therefore, a cooling structure is necessary to keep the battery cells below a certain temperature at all times. One such structure is bottom cooling, which involves circulating cooling water inside the battery pack to cool the bottom of the battery module. This would involve using a cooling structure. However, this type of cooling method causes a temperature difference between the bottom and top of the battery cell, reducing the efficiency of battery use. To improve this, it is necessary to cool the overall temperature of the battery cell uniformly. In other words, thermal balancing is required not only in the battery module but also in the battery cell itself.

[0045] This invention aims to improve the rapid charging performance and lifespan of a battery module, assembly, cell bank, or stack structure made up of numerous battery cells by reducing temperature deviations between different battery cells (top-bottom, side-center) and effectively balancing the temperature of individual battery cells.

[0046] This invention solves the problem of temperature differences occurring at different locations within a single battery cell by adding a thin-film thermal conductive material between battery cells in structures such as stacks, assemblies, modules, and banks, which combine multiple battery cells, thereby reducing temperature deviations in the planar direction of the battery cells.

[0047] Battery cells can be classified into rectangular, cylindrical, or pouch-type batteries made from cans. The various packaging materials for such battery cells are mainly made of aluminum. The present invention applies a thin-film graphite sheet or graphite layer to the packaging material of such battery cells, which is lighter and slimmer than aluminum while having superior thermal conductivity and other properties. The present invention applies the graphite layer or sheet in various ways and further adds an insulating barrier to the compression pad to suppress heat transfer between adjacent battery cells, thereby ensuring thermal balancing at the cell level and blocking flame propagation between cells.

[0048] According to the present invention, a number of battery cells can be stacked to form a single stack, assembly, or bank. In this invention, such a collection of battery cells is referred to as a battery module. Therefore, a battery module according to the present invention should be interpreted as a collection of a number of battery cells, such as a stack, assembly, or bank. And a battery pack should be understood to consist of at least one or more battery modules.

[0049] Figure 1 shows a cross-sectional structure of a battery cell packaging material according to one embodiment of the present invention. The battery cell according to the present invention may consist of an electrode assembly 10 composed of a positive electrode, a negative electrode, and an electrolyte, and a packaging material 100 that surrounds and protects the electrode assembly 10. The packaging material 100 must be made of a material that prevents the penetration / intrusion of moisture and foreign matter to prevent short circuits, allows heat exchange with the outside, but blocks the propagation of flames.

[0050] The battery cell packaging material 100 of the present invention comprises an aluminum layer 120 and a polymer layer 110, with an additional graphite layer 130 positioned on one side of the aluminum layer 120, on one side of the polymer layer 110, or between the aluminum layer 120 and the polymer layer 110. As shown in Figure 1, a PP (polypropylene) layer is provided as the polymer at the innermost interior. The aluminum layer 120 is provided on the polymer layer 110. The aluminum layer 120 maintains the rigidity of the packaging material 100 and facilitates heat conduction, while the internal PP layer 110 is responsible for insulation. The aluminum layer 120 can be formed from various aluminum alloys in addition to pure aluminum.

[0051] A graphite layer 130 is in direct contact with the outside of this aluminum layer 120. Unlike aluminum, graphite has superior thermal conductivity in the width direction compared to the thickness direction. Therefore, aluminum is placed near the battery electrode assembly to prioritize heat dissipation and thermal conduction, and graphite is applied to eliminate temperature imbalances in the plane direction of the aluminum. Thus, through the aluminum and graphite, thermal conduction and thermal balancing in the plane direction can be ensured in the battery cell. For insulation and protection of the graphite layer 130, a nylon layer 140 and a PET (polyethylene terephthalate) layer 150 are bonded to the outside to form the packaging material 100.

[0052] In the embodiment shown in Figure 1, a graphite layer 130 is placed after the polymer layer 110 and the aluminum layer 120, and these are integrally molded to form a single packaging material 100, showing the cross-sectional structure of the packaging material. In this case, the graphite layer 130 of the packaging material 100 is positioned so as to be in close contact with the aluminum layer 120, thereby allowing the heat from the aluminum layer 120 to be transferred in the planar direction and achieving planar balancing.

[0053] Figure 2 shows a battery cell as an example to which this type of packaging material 100 is applied. The battery cell in Figure 2 is a prismatic cell, in which an electrode assembly 10 is inserted into a prismatic can with an internal space and finished with leads 30. In this case, by constructing the prismatic packaging material 100 with the packaging material of Figure 1, thermal balancing in the planar direction can be ensured. Alternatively, as shown, in the case of the graphite layer 130, it may be possible to apply it partially to a relatively large area only on the parts that form a surface, excluding the corners of the packaging material.

[0054] On the other hand, Figure 3 shows another example of packaging material. In this case, a polymer layer 110 and an aluminum layer 120 are first laminated, then another polymer layer of nylon 140 and PET 150 is laminated, and finally a graphite layer 130 is bonded to the outermost layer. In other words, in this case, a battery cell is constructed using packaging material consisting only of polymer layers 110, 140, 150 and an aluminum layer 120, and then the graphite layer 130 is bonded to the outside of the packaging material through additional work. In this case, the graphite layer 130 is electrically insulated by being separated from the aluminum layer 120 through the PET layer 150 and the nylon layer 140, and thermal balancing is pursued by performing heat conduction in the planar direction.

[0055] When the graphite layer 130 is molded together with the packaging material 100, the bonding process is eliminated, which has the advantage of simplifying manufacturing. When the graphite layer 130 is bonded separately, packaging materials with and without the graphite layer can be appropriately mixed, resulting in material savings, reduced weight, and increased energy density.

[0056] On the other hand, an insulating layer 160 may be additionally bonded to the outside of the graphite layer 130. The insulating layer 160 may consist of a mica layer. The mica layer, mainly composed of mica, can perform insulation and effectively block the propagation of flames. However, since the insulating layer 160 may have lower moldability compared to the polymer, this method of bonding it separately may be considered. By applying the insulating layer 160 together, the battery cell can simultaneously achieve thermal balancing in the planar direction and flame blocking.

[0057] Figure 4 shows an example in which a graphite layer 130 is additionally bonded to the outside of a packaging material in which the polymer layer and aluminum layer are integrally molded. The graphite layer 130 is positioned to correspond to the side of the battery cell 20, and a heat insulating layer 160 may be placed on the outermost part of the packaging material 100 as shown in Figure 5. Specifically, the packaging material 100 has a graphite layer 130 additionally bonded to the outside of a packaging material in which the polymer layer and aluminum layer are integrally molded, the graphite layer 130 is folded multiple times and bonded to wrap around the battery cell 20, and a heat insulating layer 160 may be placed on the outside of the graphite layer 130 to correspond to the side of the battery cell.

[0058] In the case of Figure 4, a graphite layer 130 is bonded to the outside of the packaging material as a pouch-type battery cell 20. Then, as shown in Figure 5, by adding an insulating layer 160 to the side section excluding the lower end of the battery cell, heat balancing, flame shielding, and heat propagation shielding on the side are simultaneously achieved without impairing heat dissipation through the lower end of the battery cell 20.

[0059] Figures 6 and 7 show a battery module to which such a battery chamber is applied. As mentioned earlier, a battery module is an assembly of multiple battery cells and is a concept that encompasses all concepts such as stack, assembly, and bank.

[0060] The battery module according to the present invention includes a first battery cell 20 packaged in packaging material containing an aluminum layer and a polymer layer, and a second battery cell 20' packaged in packaging material containing an aluminum layer and a polymer layer, wherein the packaging material has a graphite layer 130 arranged in the aluminum layer, the polymer layer, or between the aluminum layer and the polymer layer. That is, a general battery cell in which a graphite layer is not applied to the packaging material can be defined as the first battery cell 20, and a battery cell in which a graphite layer is applied to the packaging material can also be defined as the first battery cell 20. The battery module of the present invention aims to reduce weight and cost by efficiently using graphite by appropriately mixing and arranging such first battery cells 20 and second battery cells 20', while simultaneously achieving performance equivalent to that of a module with graphite applied throughout in terms of thermal balancing.

[0061] Specifically, a cell bank refers to a group of battery cells gathered between compression pads. Figure 6 shows a case where there are four battery cells in the bank, while Figure 7 shows a case where there are three. Each battery cell performs basic heat dissipation through its lower end by contacting the cooling unit 50 at its lower end.

[0062] In both cases, the first battery cell 20 and the second battery cell 20' are arranged adjacent to each other. By arranging the first battery cell 20 and the second battery cell 20' in this mixed arrangement, the first battery cell 20, which does not contain a graphite layer, utilizes the graphite layer 130 of the adjacent second battery cell 20' to achieve thermal balancing in the planar direction. Therefore, in the case of the first battery cell, which does not contain a graphite layer, by arranging it in contact with the second battery cell 20', which contains a graphite layer 130, it becomes possible to omit some of the graphite, thereby saving cost and weight. Furthermore, by omitting some of the graphite layer, the overall energy density of the battery module can be increased.

[0063] Specifically, as shown in Figure 6, a pair of first battery cells 20 can be arranged adjacent to each other between a pair of second battery cells 20'. A pair of first battery cells 20 facing each other between the pair of second battery cells 20' can be arranged adjacent to each other with a graphite sheet 300 in between. In the case of a first battery cell 20 positioned in the center, thermal balancing is performed on one side by sharing the graphite layer 130 of the second battery cells 20', and on the other side by sharing the separately added graphite sheet 300. In such a graphite layer 130 and graphite sheet 300, an insulating layer 160 can be added as shown in Figure 3 to prevent the diffusion of heat and flames.

[0064] On the other hand, in the case of Figure 7, the second battery cell 20' is located between a pair of first battery cells 20. In this case, the graphite layer 130 contained in the central second battery cell 20' is shared, and the first battery cells 20 on both sides perform thermal balancing together.

[0065] Compression pads 500 are placed on the outside of each first battery cell 20, and a graphite sheet 300 may be placed between the compression pads 500 and the first battery cell 20. Thus, the first battery cell 20 performs thermal balancing on one side by sharing the graphite layer 130 of the second battery cell 20', and on the other side by using the separately added graphite sheet 300. As shown in Figure 3, an insulating layer 160 can be added to the graphite layer 130 and graphite sheet 300 to prevent the diffusion of heat and flames.

[0066] On the other hand, Figures 8 and 9 show that the graphite sheet 300 is applied to the compression pad 500. The compression pad 500 is molded from a compressible material and plays a role in absorbing the contraction / expansion caused by the charging and discharging of the battery cells. Graphite sheets 300 are bonded to both sides of such a compression pad 500 to realize thermal balancing of the adjacent first battery cells 20.

[0067] Furthermore, by molding the compression pad 500 to include an insulating layer 160 in its center, it can also perform the function of blocking heat diffusion or flame propagation between battery cells that are placed with the compression pad 500 in between.

[0068] Figure 10 shows a battery pack BP to which the battery module according to the present invention is applied, and a vehicle V to which the battery pack BP is installed. In the present invention, by applying a graphite layer or sheet to the side surface of the battery cell or compression pad, thermal balancing at the cell level can be effectively achieved. Furthermore, heat dissipation is also improved by bending the graphite layer or sheet and bringing it into contact with the cooling section below.

[0069] Furthermore, by folding a single graphite layer or sheet to simultaneously cover both sides and the bottom of a single battery cell, assembly is easy. The compression pad, likewise incorporating an insulating layer along with the graphite sheet, improves the thermal balancing of the battery cell while preventing heat transfer.

[0070] Although illustrated and described in relation to specific embodiments of the present invention, it will be obvious to those ordinary in the art that the present invention can be improved and modified in various ways without departing from the technical spirit of the invention provided by the following claims.

Claims

1. A battery cell packaged in packaging material containing an aluminum layer and a polymer layer, wherein the packaging material is characterized in that a graphite layer is disposed in the aluminum layer, in the polymer layer, or between the aluminum layer and the polymer layer.

2. The battery cell according to claim 1, characterized in that the graphite layer of the packaging material is arranged to be in close contact with the aluminum layer.

3. The battery cell according to claim 1, characterized in that the packaging material has an aluminum layer arranged on the outside of a polymer layer, and a graphite layer arranged on the outside of the aluminum layer.

4. The battery cell according to claim 1, characterized in that the packaging material has a polymer layer and an aluminum layer integrally molded together, with a graphite layer additionally bonded to the outside.

5. The battery cell according to claim 1, characterized in that the packaging material has a graphite layer positioned to correspond to the side surface of the battery cell.

6. The battery cell according to claim 1, characterized in that the packaging material has an insulating layer on the outermost surface.

7. The battery cell according to claim 1, characterized in that the packaging material has a polymer layer and an aluminum layer integrally molded, with an additional graphite layer bonded to the outside, the graphite layer is folded multiple times and bonded to enclose the battery cell, and an insulating layer is placed on the outside of the graphite layer at a position corresponding to the side of the battery cell.

8. A first battery cell packaged in packaging material containing an aluminum layer and a polymer layer, and The packaging material includes a second battery cell in which a graphite layer is placed in the aluminum layer, or in the polymer layer, or between the aluminum layer and the polymer layer. A battery module characterized in that a first battery cell and a second battery cell are arranged adjacent to each other.

9. The battery module according to claim 8, characterized in that a pair of first battery cells are arranged adjacent to each other between a pair of second battery cells.

10. The battery module according to claim 9, characterized in that a pair of first battery cells are arranged adjacent to each other with a graphite sheet in between.

11. The battery module according to claim 9, characterized in that a compression pad is placed on the outside of each of the second battery cells.

12. The battery module according to claim 8, characterized in that a second battery cell is positioned between a pair of first battery cells.

13. The battery module according to claim 12, characterized in that a compression pad is arranged on the outside of each of the first battery cells.

14. The battery module according to claim 13, characterized in that a graphite sheet is placed between the compression pad and the first battery cell.

15. The battery module according to claim 8, characterized in that at least one first battery cell and at least one second battery cell together constitute a cell bank, and compression pads are arranged on the outer sides of both sides of the cell bank.

16. The battery module according to claim 15, characterized in that a graphite sheet is placed between the compression pad and the adjacent first battery cell.

17. The battery module according to claim 15, characterized in that the compression pad includes an insulating layer.

18. A battery pack comprising a battery module according to any one of claims 8 to 17.

19. A vehicle characterized by including a battery module according to any one of claims 8 to 17.

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