Battery modules, battery packs containing them, and automobiles

Abstract

The present invention relates to a battery module comprising: a cell stack including a plurality of battery cells; a module case configured to house the cell stack; and a thermal conductive layer provided between the module case and the cell stack, configured such that the adhesive strength differs from the outside to the inside.

Description

[[TECHNICAL FIELD]]

[0001] The present invention relates to a battery module, a battery pack including the same, and an automobile.

[0002] This application claims priority based on Korean Patent Application No. 10-2023-0162568 filed on November 21, 2023, and all contents disclosed in the specification and drawings of the said application are incorporated into this application. [[BACKGROUND ART]]

[0003] Secondary batteries, which can be easily applied according to product groups and have electrical characteristics such as high energy density, are widely applied not only to portable devices, but also to electric vehicles (EV) driven by electric drive sources, hybrid electric vehicles (HEV) and the like. Such secondary batteries are attracting attention as new energy sources for improving energy efficiency and being environmentally friendly, because they not only have the primary advantage of dramatically reducing the use of fossil fuels, but also generate no by-products accompanying energy use at all.

[0004] Currently, types of secondary batteries widely used include lithium ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and the like. When high output voltage is required, a plurality of battery cells may be connected in series to form a battery module or a battery pack. In addition, in order to increase charge and discharge capacity, a plurality of battery cells may be connected in parallel to form a battery module or a battery pack.

[0005] When configuring a battery pack by connecting multiple battery cells in series or parallel, it is common practice to first configure a battery module containing at least one battery cell, and then use this module to add other components to form a battery pack or battery rack. Alternatively, more recently, cell-to-pack battery packs have been manufactured in which multiple battery cells are directly housed in a pack housing or similar without modularization.

[0006] On the other hand, in the case of conventional battery modules, a thermally conductive adhesive for cooling the battery cells may be applied to one surface of the cell stack, which consists of such stacked battery cells. In such conventional battery modules, various problems can occur when swelling of the battery cells occurs during the charge-discharge cycle.

[0007] For example, when battery cell swelling occurs, the entire battery cell in the cell stack moves towards the outermost casing, while one side of the cell stack that is in direct contact with the thermal conductive adhesive is fixed by the hardened adhesive. This can lead to a problem where parts of the cell case with relatively weaker elongation rates are damaged.

[0008] Alternatively, when battery cells swell, the movement of the cell stack can damage the hardened thermal conductive adhesive, leading to partial or complete structural collapse of the cell stack or the battery device. In this process, the battery cells may detach from the thermal conductive adhesive, which can reduce the heat dissipation performance of the battery cells. [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] This invention has been made in view of the above-mentioned problems, and aims to provide a battery module with an improved structure that ensures stability even when a swelling phenomenon occurs, as well as a battery pack including the same and an automobile, etc.

[0010] However, the technical problems that the present invention aims to solve are not limited to those described above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description of the invention. [Means for solving the problem]

[0011] To achieve the above objectives, a battery module according to one embodiment of the present invention includes a cell stack comprising a plurality of battery cells, a module case configured to house the cell stack, and a thermal conductive layer provided between the module case and the cell stack, configured such that the adhesive strength differs from the outside to the inside.

[0012] The heat conductive layer may be configured such that the adhesive strength weakens as you move from the outside to the inside.

[0013] The thermal conductive layer may include a first thermal conductive layer configured to contact the module case, and a second thermal conductive layer provided inside the first thermal conductive layer and configured to contact the cell laminate.

[0014] The first thermal conductive layer and the second thermal conductive layer may be configured to have different adhesive strengths.

[0015] The adhesive strength of the second thermal conductive layer may be configured to be weaker than that of the first thermal conductive layer.

[0016] The second thermal conductive layer may be made of a material with a lower degree of hardening than the first thermal conductive layer.

[0017] The second thermal conductive layer may consist of a material containing silicone.

[0018] The second thermally conductive layer may be configured to surround a terminal end of the battery cell.

[0019] The second thermally conductive layer may be configured to be insertable between the plurality of battery cells when the battery cell swells.

[0020] The first thermally conductive layer may be configured to contact a terminal end of the battery cell.

[0021] The first thermally conductive layer may be configured to surround a terminal end of the battery cell.

[0022] The thermally conductive layer may be configured to include a portion where the thickness of the second thermally conductive layer varies as proceeding toward an outermost direction in a stacking direction of the battery cells.

[0023] The present invention provides a battery pack comprising the battery module according to the present invention.

[0024] The present invention also provides a vehicle comprising the battery module according to the present invention. Effects of the Invention

[0025] According to one embodiment of the present invention, stability against swelling of a battery device including battery cells, that is, a battery module or a battery pack, can be ensured.

[0026] In particular, according to one embodiment of the present invention, in a battery module or a battery pack including a plurality of battery cells stacked together, the stacked state of the cells can be stably maintained in a steady state, and damage to components of the battery module such as battery cells can be prevented when swelling occurs.

[0027] Further, according to one embodiment of the present invention, when swelling occurs, collapse of the structure of the battery device due to damage of the curable adhesive can be prevented or suppressed.

[0028] Further, according to one embodiment of the present invention, it is possible to prevent the problem that the battery cell detaches from the thermally conductive adhesive due to the occurrence of swelling, resulting in a decrease in heat dissipation function. Thereby, the cooling performance of the battery device can be sustained.

[0029] Therefore, according to this aspect of the present invention, the cycle performance of the battery device is improved. That is, according to various aspects of the present invention, a battery device that can be stably used for a long time and has an improved service life can be provided.

[0030] In addition, the present invention can have various other effects. Regarding these, they will be described in each embodiment, and the description of effects that can be easily analogized by those skilled in the art will be omitted.

[0031] The following drawings attached to the present specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of the present invention together with the detailed description of the invention. Therefore, the present invention should not be construed as being limited only to the matters described in the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] [Figure 1] It is an overall perspective view of a battery module according to an embodiment of the present invention. [Figure 2] It is an exploded perspective view of a battery module according to an embodiment of the present invention. [Figure 3] It is a cross-sectional view of a battery module according to an embodiment of the present invention. For example, FIG. 3 is a view showing a cross-section taken along line I-I' of FIG. 1. [Figure 4] It is a cross-sectional view showing a state where swelling occurs in a battery cell in the battery module according to an embodiment of the present invention. [Figure 5]This is a cross-sectional view of a battery module according to another embodiment of the present invention. [Figure 6] This figure shows an example of a thermal conductive layer included in a battery module according to another embodiment of the present invention. [Figure 7] This is an enlarged view of section A in Figure 5. [Figure 8] This is an enlarged view of portion A in Figure 5, showing the case where swelling occurs in the battery cell in a battery module according to another embodiment of the present invention. [Figure 9] This is an enlarged cross-sectional view of a battery module according to yet another embodiment of the present invention. [Figure 10] This is an enlarged cross-sectional view of a battery module according to yet another embodiment of the present invention. [Figure 11] This is a cross-sectional view of a battery module according to yet another embodiment of the present invention. [Figure 12] This is an enlarged view of section B in Figure 11. [Figure 13] This is a cross-sectional view of a battery module according to yet another embodiment of the present invention. [Figure 14] This is a cross-sectional view of a battery module according to yet another embodiment of the present invention. [Figure 15] This is a schematic perspective view showing the configuration of a battery pack according to one embodiment of the present invention. [Figure 16] This is a schematic perspective of an automobile based on one embodiment of the present invention. [Modes for carrying out the invention]

[0033] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. Prior to this, terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner and concept appropriate to the technical idea of ​​the present invention, in accordance with the principle that the inventor himself can appropriately define the concepts of terms in order to best describe the invention.

[0034] Therefore, it should be understood that the embodiments and configurations shown in the drawings described herein represent only one of the most preferred embodiments of the present invention and do not represent the entirety of the technical concept of the present invention, and that there are various equivalents and modifications that can be substituted for them at the time of this application.

[0035] The present invention includes various embodiments. For configurations that are substantially identical or similar to each embodiment, redundant explanations will be omitted, and the focus will be on the differences.

[0036] In this specification, terms indicating direction such as up, down, left, right, front, and back may be used, but such terms are for illustrative purposes only, and it will be obvious to those skilled in the art that they can change depending on the position of the object in question, the observer's position, etc.

[0037] For example, in an embodiment of the present invention, the X-axis direction shown in the drawing is the left-right direction, the Y-axis direction is the front-back direction perpendicular to the X-axis direction in the horizontal plane (XY plane), i.e., the longitudinal direction of the battery cell, and the Z-axis direction may mean the up-down direction (vertical direction) perpendicular to both the X-axis and Y-axis directions, i.e., the height direction of the battery cell.

[0038] Figure 1 is an overall perspective view of a battery module according to one embodiment of the present invention, Figure 2 is an exploded perspective view of a battery module according to one embodiment of the present invention, and Figure 3 is a cross-sectional view of a battery module according to one embodiment of the present invention. Figure 4 is a cross-sectional view of a battery module according to one embodiment of the present invention when swelling occurs in the battery cells. For example, Figures 3 and 4 are diagrams showing the cross-section along line I-I' in Figure 1.

[0039] Referring to Figures 1 to 4, the battery module 10 according to the present invention includes a cell stack 100, a module case 200, and a thermal conductive layer 300.

[0040] The cell stack 100 may comprise one or more battery cells 110, in particular, a plurality of battery cells 110. Here, each battery cell 110 may represent a single secondary battery or a group of multiple secondary batteries. In this specification, a battery cell 110 will be described as representing a single secondary battery.

[0041] Multiple battery cells 110 may include an electrode assembly, a cell case housing the electrode assembly, and electrode leads 111 connected to the electrode assembly and extended to the outside of the cell case to function as electrode terminals. In this case, the shape of the battery case can be configured in various ways, and depending on the shape of the battery case, the battery cells 110 can be classified into pouch-type cells, cylindrical cells, prismatic cells, etc. Since such types of battery cells 110 are publicly known at the time of filing of the present invention, a detailed description will be omitted. The present invention is applicable to all various forms of secondary batteries known at the time of filing of the present invention and is not limited to any particular type of secondary battery.

[0042] In the cell stack 100, the multiple battery cells 110 may be configured to be stacked in at least one direction. For example, the multiple battery cells 110 may be stacked horizontally, particularly in the left-to-right direction (X-axis direction), as shown in Figure 2. The multiple battery cells 110 provided in the cell stack 100 may be electrically connected to each other in series and / or parallel by busbars (not shown) or the like.

[0043] Although not shown in the diagram, the cell stack 100 may further comprise barriers in addition to the battery cells 110. One or more, and especially more than one, barriers may be provided in a single cell stack 100. Furthermore, the barriers may be positioned in the cell stack 100 between adjacent battery cells 110, or on the outermost edge in the stacking direction of the cell stack 100. The barriers are plate-shaped and may face the surface of the battery cell 110, particularly the outer surface of the housing portion of a pouch-type cell.

[0044] On the other hand, referring to Figure 2, the module case 200 may be configured to accommodate the cell stack 100. Specifically, the module case 200 may be configured to have a storage space, in which the cell stack 100 is housed.

[0045] For example, the module case 200 may have a limited storage space by comprising a case body 210, an upper plate 220, and an end plate 230. The cell stack 100 can then be positioned within this limited storage space. The module case 200 may be made of at least partially metal and / or plastic material.

[0046] At least some of the various plate-like members constituting the module case 200 can be integrated with each other. For example, as shown in Figure 2, the module case 200 may have a U-frame-shaped case body 210 in which the bottom plate, left side plate, and right side plate are integrated with each other, and the top plate 220 and end plates 230 may be configured to cover or seal the top, front, and rear of the case body 210. In this case, various methods such as welding, bonding, bolting, and hook fastening can be used to connect and fix the top plate 220 and end plates 230 to the case body 210. Alternatively, the module case 200 may be manufactured in a mono-frame form in which the top plate 220 and the case body 210 are integrated with each other. Alternatively, the module case 200 may be constructed by separately manufacturing each plate material and then joining and fixing it together by welding or the like. However, the present invention is not limited to such specific materials or forms of the module case 200.

[0047] The thermal conductive layer 300 may be provided between the cell laminate 100 and the module case 200. For example, referring to Figure 3, the thermal conductive layer 300 may be provided between one side of the cell laminate 100, for example, the lower part, and the lower surface of the module case 200.

[0048] The heat conduction layer 300 can be configured to transfer heat between the cell stack 100 and the module case 200. The battery cell 110 may generate heat during use, and if this heat is not properly dissipated, the performance of the battery cell 110 cannot be reliably guaranteed, and in severe cases, it may lead to thermal runaway, ignition, or explosion of the battery cell. Therefore, the heat generated in the battery cell 110 needs to be properly dissipated to the outside from the module case 200. In this case, the heat conduction layer 300 can ensure stable cooling performance for the battery module by facilitating heat transfer between the battery cell 110 and the module case 200.

[0049] The thermal conductive layer 300 may contain a material that conducts heat. In particular, the thermal conductive layer 300 may be made of a resin material, in which case it may be referred to as a thermal resin. The thermal conductive layer 300 may include a variety of materials, typically such as urethane, silicone, and epoxy. The thermal conductive layer 300 may also be expressed using terms such as TIM (Thermal Interface Material) or potting resin, and as the material for the thermal conductive layer 300 of the battery module 10 according to the present invention, a variety of thermal resins or TIMs known at the time of filing of the present invention may be used.

[0050] Furthermore, the thermal conductive layer 300 may be configured to adhere the cell laminate 100 to the module case 200. For this purpose, the thermal conductive layer 300 may include an adhesive component. For example, as shown in Figure 3, if the thermal conductive layer 300 is located below the cell laminate 100, the thermal conductive layer 300 can adhere and fix the lower part of the cell laminate 100 to the lower surface of the module case 200.

[0051] The thermal conductive layer 300 may be interposed between the entire battery cell 110 provided in the cell stack 100 and the module case 200. That is, the thermal conductive layer 300 may be configured to be in direct contact with all the battery cells 110 included in the cell stack 100. According to such an embodiment of the present invention, heat can be dissipated from all the battery cells 110 included in the battery module 10 via the thermal conductive layer 300. This further improves the overall cooling performance of the battery module 10.

[0052] In particular, in the battery module 10 according to the present invention, the thermal conductive layer 300 adheres at least a portion of the cell stack 100 to the module case 200, and the adhesive strength may be configured to vary. Here, adhesive strength may mean the force or strength with which the cell stack 100 and the module case 200 are fixed by the thermal conductive layer 300.

[0053] Specifically, the thermal conductive layer 300 may be configured such that its adhesive strength differs from the outside to the inside. That is, the thermal conductive layer 300 may be configured such that its adhesive strength differs along a direction perpendicular to one side of the module case 200. The adhesive strength of the thermal conductive layer 300 may change progressively from the outside to the inside, or it may be formed as a multilayer structure with layers having different adhesive strengths.

[0054] On the other hand, in this specification, the direction toward the center of the battery module 10 is defined as the inward direction, and the direction toward the outside of the battery module 10 is defined as the outward direction. Such inward and outward may be concepts that indicate relative positions.

[0055] As a more specific example, in the implementation configuration shown in Figure 3, when the thermal conductive layer 300 is interposed between the lower part of the cell stack 100 and the lower surface of the module case 200, the adhesive strength of the thermal conductive layer 300 may be configured to differ in the vertical direction. In such a case, the adhesive strength of the portions in which each of the battery cells 110 contained in the cell stack 100 contacts the thermal conductive layer 300 may be configured to differ in the vertical direction.

[0056] When a swelling phenomenon occurs in a cell stack 100, which is provided with multiple battery cells 110 stacked on top of each other, the battery cells 110 move in the stacking direction. Because one side of the cell stack 100 that is in contact with the thermal conductive layer 300 is fixed, damage or breakage of the battery cells 110 may occur. However, as shown in Figure 4, in the battery module 10 of the present invention, the adhesive force of the thermal conductive layer 300 is configured to differ from the outside to the inside, thereby providing the battery cells 110 with a degree of freedom to move up to a certain level. Therefore, damage to the battery cells 110 when swelling occurs is suppressed. Thus, the battery module 10 according to the present invention ensures stability or safety against swelling.

[0057] In particular, the thermal conductive layer 300 may be configured such that the adhesive strength decreases, at least partially, as you move from the outside to the inside. That is, the portion of the thermal conductive layer 300 located on the inside may be configured to have weaker adhesive strength than the portion located on the outside. For example, in the embodiment shown in Figure 3, the thermal conductive layer 300 may be configured so that the adhesive strength of the upper portion is weaker than that of the lower portion.

[0058] Here, "weak adhesive force" can mean both that there is some adhesive force, but it is relatively weak compared to other parts, and that there is zero adhesive force, i.e., no adhesive force at all. For example, the inner part of the heat conduction layer 300 in Figure 3 can have its adhesive force released even with a relatively weaker force compared to the outer part of the heat conduction layer 300. Alternatively, the inner part of the heat conduction layer 300 may not adhere to the battery cell 110 at all, and may only serve the role of transferring heat.

[0059] In areas where the cell laminate 100 and the thermal conductive layer 300 are in direct contact, fixing the battery cell 110 with strong adhesive force can increase the likelihood of damage due to swelling. However, in the implementation configuration described above, by weakening the adhesive force to the thermal conductive layer 300 on the inner part of the battery cell 110, a certain degree of freedom of movement for the battery cell 110 can be granted. This protects the battery cell 110 from surrounding stress and impact when swelling occurs. Therefore, the stability or safety of the battery module 10 against swelling can be further ensured.

[0060] On the other hand, if the adhesive force to the thermal conductive layer 300 is weakened on the inner portion of the battery cell 110, the adhesive force to the module case 200 may be weakened. However, according to the above-described embodiment of the present invention, by strengthening the adhesive force to the thermal conductive layer 300 on the outer portion of the battery cell 110, damage to the battery cell 110 during swelling is prevented, and the adhesive force to the module case 200 on the outer portion of the battery cell 110 can be maintained. Furthermore, according to the above-described embodiment of the present invention, the cell laminate 100 and the module case 200 can be reliably insulated.

[0061] Figure 5 is a cross-sectional view of a battery module according to another embodiment of the present invention, and Figure 6 is a diagram showing an example of a thermal conductive layer included in a battery module according to another embodiment of the present invention.

[0062] Referring to Figures 5 and 6, the thermal conductive layer 300 may include a first thermal conductive layer 310 and a second thermal conductive layer 320. Here, the first thermal conductive layer 310 and the second thermal conductive layer 320 are unit components (unit members) of the thermal conductive layer 300 and may consist of different types, i.e., different materials.

[0063] The first thermal conductive layer 310 and the second thermal conductive layer 320 may be arranged along the direction from the outside to the inside. Specifically, the first thermal conductive layer 310 may be configured to be in contact with the module case 200. The first thermal conductive layer 310 may indirectly or directly fix the cell laminate 100 to the module case 200.

[0064] The second thermal conductive layer 320 may be provided inside the first thermal conductive layer 310. The second thermal conductive layer 320 may be configured to be in contact with the cell laminate 100. This allows the second thermal conductive layer 320 to be interposed between the first thermal conductive layer 310 and the cell laminate 100. That is, the modules may be arranged to be stacked in the order of module case 200, first thermal conductive layer 310, second thermal conductive layer 320, and cell laminate 100 as you move from the outside to the inside.

[0065] In particular, the thermal conductive layer 300, which is arranged on one side of the cell laminate 100, may be configured in a plate shape. In this case, the different types of unit layers constituting the thermal conductive layer 300, that is, two or more thermal conductive unit layers, may each be configured in a plate shape and arranged butt against each other. For example, referring to the configuration shown in Figures 5 and 6, one first thermal conductive layer 310 and one second thermal conductive layer 320 may be horizontally laid plates and arranged parallel to each other in the vertical direction.

[0066] The first thermal conductive layer 310 and the second thermal conductive layer 320 may be configured to have different adhesive strengths. In particular, the adhesive strength of the second thermal conductive layer 320 may be configured to be weaker than that of the first thermal conductive layer 310. Such a second thermal conductive layer 320 may be configured to allow the battery cell 110 to move when swelling occurs.

[0067] According to this embodiment, the battery module 10 according to the present invention can be provided with a simple structure. Furthermore, according to this embodiment, the battery module 10 according to the present invention can be manufactured more easily. In particular, according to the above embodiment, the problem of the battery cell 110 being easily damaged by swelling can be prevented more effectively.

[0068] The thermal conductive layer 300 may be configured to have partially different degrees of curing. The degree of curing refers to the degree to which it has solidified, and under the same conditions, for example at room temperature, a thermal conductive paste with a high degree of curing will have higher adhesive strength (fixing strength) than a thermal conductive paste with a low degree of curing. Techniques for measuring or determining the degree of curing are publicly known at the time of filing of this invention, so a detailed explanation thereof will be omitted.

[0069] In particular, the thermal conductive layer 300 may be configured such that the degree of hardening differs from the outside to the inside. For example, in the embodiments shown in Figures 5 and 6, the first thermal conductive layer 310 and the second thermal conductive layer 320 may be configured to have different degrees of hardening.

[0070] In this configuration, the second thermal conductive layer 320 may be configured to have a lower degree of hardening than the first thermal conductive layer 310. That is, in the steady state after the battery module is manufactured, the first thermal conductive layer 310 is maintained in a relatively harder state than the second thermal conductive layer 320, and a strong adhesive force with the module case 200 can be maintained. In contrast, the second thermal conductive layer 320 may be provided so as to not harden into a solid state, but remain in a gel-like state. This allows the second thermal conductive layer 320 to remain in a relatively softer state than the first thermal conductive layer 310, and can be configured to allow a certain degree of movement of the battery cells 110.

[0071] According to the above-described embodiment of the present invention, by configuring the heat conductive layer 300 to have a low degree of hardening in the portion that contacts the inner portion of the battery cell 110, the battery cell 110 can be made to move sufficiently when the cell laminate 100 swells. This makes it possible to minimize damage to the battery cell 110 during swelling.

[0072] In particular, the second thermal conductive layer 320 may be formed from a silicone-containing material. More specifically, the first thermal conductive layer 310 may be made of a urethane-based thermal resin, and the second thermal conductive layer 320 may be made of a gel-state silicone-based thermal resin.

[0073] On the other hand, the fact that the thermal conductive layer 300 has partially different degrees of hardening can also be expressed as having partially different properties. Here, different properties may include being a perfectly elastic body, and being in a solid, gel, or sol state. That is, the difference in the partially hardened degree of the thermal conductive layer 300 can be indicated by differences in elasticity, viscosity, fluidity, etc. In particular, the thermal conductive layer 300 may have both a solid portion and a gel portion. For example, the first thermal conductive layer 310 may be a curable resin in a perfectly elastic state, while the second thermal conductive layer 320 may be an uncured resin in a gel state.

[0074] Figure 7 is an enlarged view of portion A in Figure 5. Figure 8 is an enlarged view of portion A in Figure 5 in a battery module according to another embodiment of the present invention, in which swelling occurs in the battery cell.

[0075] Referring to Figure 7, the second thermal conductive layer 320 may be configured to surround the end portion of the battery cell 110. That is, the end portion of the battery cell 110 may be configured to be surrounded by the second thermal conductive layer 320. The entire battery cell 110 contained in the cell stack 100 may be configured to be inserted into the second thermal conductive layer 320. In the above embodiment, the cell stack 100 does not have to be in direct contact with the first thermal conductive layer 310. The cell stack 100 is in contact only with the second thermal conductive layer 320, which has weak adhesive force, while the first thermal conductive layer 310, which has strong adhesive force, is interposed on the outside of the second thermal conductive layer 320, and the second thermal conductive layer 320 can be fixed to the module case 200. In this way, the cell stack 100 can be indirectly fixed to the module case 200 by the first thermal conductive layer 310.

[0076] In this case, the second thermal conductive layer 320 may be interposed between the end portions of the battery cell 110. More specifically, the battery cell 110 may include a housing portion for housing an electrode assembly and a sealing portion formed by sealing the outer portion of the housing portion. The sealing portion is provided to be in contact with the second thermal conductive layer 320, and the second thermal conductive layer 320 may be interposed between the sealing portions of the battery cell 110.

[0077] In particular, as shown in the embodiment in Figure 8, the second thermal conductive layer 320 may be configured to be insertable between multiple battery cells 110 when swelling occurs in the battery cells 110. The second thermal conductive layer 320 may also be interposed between the battery cells 110, especially between the sealing portions, even when swelling does not occur in the battery cells 110. Furthermore, when swelling occurs in the battery cells 110, the spacing between the battery cells 110 widens, and a gap may also be formed between the housing portions. As a result, the second thermal conductive layer 320 may even be interposed between the housing portions of the battery cells 110.

[0078] According to the above-described embodiment of the present invention, the shape of the second thermal conductive layer 320, which has weak adhesive force and fluidity, can be deformed depending on whether or not swelling occurs in the battery cell 110. In particular, when the second thermal conductive layer 320 is inserted between the battery cells 110, the contact area between the battery cells 110 and the second thermal conductive layer 320 can be increased. This further improves the cooling efficiency of the battery cells 110. It also further improves the insulation performance between the battery cells 110.

[0079] Figure 9 is an enlarged cross-sectional view of a battery module according to yet another embodiment of the present invention. Figure 9 is an enlarged view of portion A of Figure 5.

[0080] Unlike the embodiment shown in Figure 8, the first thermal conductive layer 310 may be configured to directly fix the cell laminate 100 to the module case 200.

[0081] For example, as shown in Figure 9, the first thermal conductive layer 310 may be configured to contact the end portion of the cell stack 100. That is, the thermal conductive layer 300 may be interposed on one surface of the cell stack 100, and the end portion of each battery cell 110 may be configured to contact the interface between the first thermal conductive layer 310 and the second thermal conductive layer 320.

[0082] According to the above-described embodiment of the present invention, when swelling occurs in the battery cell 110, the first thermal conductive layer 310 provides adhesive force to the cell stack 100, thereby preventing the overall structure of the cell stack 100 from collapsing significantly even under shocks such as vibration. As a result, while some movement of the cell stack 100 is permitted, the overall structural rigidity and structural stability of the cell stack 100 can be improved.

[0083] Figure 10 is an enlarged cross-sectional view of a battery module according to yet another embodiment of the present invention. Figure 10 is an enlarged view of portion A of Figure 5.

[0084] Alternatively, as shown in the embodiment in Figure 10, the first thermal conductive layer 310 may be configured to surround the end portion of the battery cell 110. In other words, the end portion of the battery cell 110 may be inserted into the first thermal conductive layer 310. This allows the end portion of the battery cell 110 to be surrounded not only by the second thermal conductive layer 320 but also by the first thermal conductive layer 310. In this case, the contact area between the battery cell 110 and the strongly adhesive first thermal conductive layer 310 may increase.

[0085] In the above-described embodiment of the present invention, the contact area of ​​the first thermal conductive layer 310 with respect to all battery cells 110 contained in the cell stack 100 is maximized. According to the above-described embodiment of the present invention, the adhesive force between the cell stack 100 and the module case 200 is ensured, so overall structural collapse of the cell stack 100 is prevented even under shocks such as vibrations. Therefore, the overall structural rigidity and structural stability of the cell stack 100 can be ensured.

[0086] Figure 11 is a cross-sectional view of a battery module according to yet another embodiment of the present invention, and Figure 12 is an enlarged view of portion B of Figure 11.

[0087] Referring to Figures 11 and 12, the thermal conductive layer 300 may be configured such that its adhesive strength differs as it progresses towards the outermost edge in the stacking direction of the battery cells 110. That is, the adhesive strength of the thermal conductive layer 300 may be configured to differ not only in the direction perpendicular to one side of the module case 200, but also along the direction in which the battery cells 110 are stacked. In particular, the thermal conductive layer 300 may be configured, at least partially, so that in the direction in which the multiple battery cells 110 are stacked in the cell stack 100, the portion located on the outer edge has weaker adhesive strength than the portion located in the center.

[0088] Specifically, the thermal conductive layer 300 may be configured to include portions where the thickness of the second thermal conductive layer 320 differs. In such a case, the thickness of the first thermal conductive layer 310 may also differ according to the thickness of the second thermal conductive layer 320. The thicknesses of the first thermal conductive layer 310 and the second thermal conductive layer 320 may be constant or different.

[0089] As a more specific example, in the embodiment shown in Figure 11, the second thermal conductive layer 320 may be configured such that the portion located in the center of the cell stack 100 is thinner than the portion located on the outer edge of the cell stack 100. This allows the battery cells 110 located in the center of the cell stack 100 to be more strongly bonded, while the battery cells 110 located on the outer edge of the cell stack 100 can move more freely.

[0090] When multiple battery cells 110 are stacked in one direction, for example, left-right (X-axis direction), during swelling, the battery cells 110 located on the outer casing may be pushed more than the battery cells 110 located in the center. As a result, if the battery cells 110 are fixed with the same adhesive force, the outer cells are more likely to be damaged due to swelling. However, in the above-described configuration, by making the adhesive force to the thermal conductive layer 300 weaker for the outer cells than for the inner cells, a certain degree of freedom of movement for the battery cells 110 can be granted. Therefore, when swelling occurs, problems such as damage to the outer cells and collapse of the entire cell stack 100 structure can be suppressed.

[0091] Referring to Figures 11 and 12, the thermal conductive layer 300 may be configured such that its width gradually changes along the stacking direction of the battery cells 110. In such a case, the width of the second thermal conductive layer 320 may change along the vertical direction at the portion where one battery cell 110 is in contact with the thermal conductive layer 300. In particular, the first thermal conductive layer 310 may be formed to bulge as it moves from the ends to the center in the left-right direction. That is, the width of the first thermal conductive layer 310 may gradually increase as it moves from the ends to the center in the front-back direction, with the center being the thickest. The second thermal conductive layer 320 may be formed to be thicker at the ends in the left-right direction, corresponding to the shape of the first thermal conductive layer 310. That is, the width of the second thermal conductive layer 320 may gradually decrease as it moves from the ends to the center in the left-right direction, with the center being the thinnest.

[0092] In this case, as shown in Figure 12, at least some of the battery cells 110 may have a boundary line between the first thermal conductive layer 310 and the second thermal conductive layer 320 formed as a diagonal or curved line. In particular, for battery cells 110 included in a cell stack 100, the contact area of ​​the second thermal conductive layer 320, which has weaker adhesive force, decreases as you move towards the center of the cell stack 100, while the contact area of ​​the first thermal conductive layer 310, which has stronger adhesive force, may increase. In particular, for battery cells 110 located on the outermost edge in the stacking direction of the battery cells 110, fluidity is ensured by configuring a large contact area with the second thermal conductive layer 320, and such a contact area of ​​the second thermal conductive layer 320 may gradually increase as you move outwards.

[0093] Figure 13 is a cross-sectional view of a battery module according to yet another embodiment of the present invention.

[0094] Referring to Figure 13, similar to the embodiment in Figure 11, the second thermal conductive layer 320 may be formed with a thicker width at its outermost edge in the stacking direction of the battery cells 110, and the first thermal conductive layer 310 may be formed with a thicker width at its central part in the stacking direction of the battery cells 110. Furthermore, the thermal conductive layer 300 may include a portion where the boundary line between the second thermal conductive layer 320 and the first thermal conductive layer 310 is shaded.

[0095] In this configuration, the contact area of ​​the first thermal conductive layer 310 and / or the second thermal conductive layer 320 in the vertical direction can be changed by a constant rate for at least some of the battery cells 110 included in the cell stack 100. This allows the change in the fixing force (adhesion force) between the multiple battery cells 110 stacked on top of each other to be constant and gradual.

[0096] Figure 14 is a cross-sectional view of a battery module according to yet another embodiment of the present invention.

[0097] Referring to Figure 14, the entire battery cell 110 contained in the cell stack 100 has strong adhesive force and can come into contact with the first thermal conductive layer 310 which constitutes a unit member. However, at least some of the battery cells 110 may be configured to have different contact areas with the first thermal conductive layer 310.

[0098] For example, in the case of a battery cell 110 located towards the center in the cell stacking direction, as shown in region S1, it may be in contact with only the first thermal conductive layer 310 overall. On the other hand, in the case of a battery cell 110 located towards the outer edge in the cell stacking direction, as shown in region S3, it may be in contact with only the second thermal conductive layer 320 overall. In particular, the outermost cell may be included in region S3, and such an outermost cell may not be in contact with the first thermal conductive layer 310, but only with the second thermal conductive layer 320, and thus may have fluidity.

[0099] Furthermore, as shown in the region indicated by S2, the thickness of the second thermal conductive layer 320 may be increased as one moves towards the outer casing in the cell stacking direction. In addition, in the region indicated by S2, as one moves outward in the cell stacking direction, the contact area of ​​the first thermal conductive layer 310 with respect to the battery cell 110 may gradually decrease, while the contact area of ​​the second thermal conductive layer 320 may gradually increase.

[0100] According to this embodiment of the present invention, the first thermal conductive layer 310 provides adhesive force to the battery cell 110 located in the center of the cell stack 100, thereby preventing the overall structure of the cell stack 100 from collapsing significantly due to vibration, swelling, etc. This improves the overall structural rigidity and structural stability of the cell stack 100.

[0101] Furthermore, in the above-described configuration, the contact area of ​​the second thermal conductive layer 320 with respect to the outermost cell is the largest among all the battery cells 110 included in the cell stack 100. This allows for partial movement during swelling, thereby further reliably reducing the possibility of damage to the outermost cell due to swelling.

[0102] Furthermore, as shown in the embodiments in Figures 11, 13, and 14, when the boundary lines of the first thermal conductive layer 310 and / or the second thermal conductive layer 320 are configured as diagonal lines or curves, a gradual change in the adhesive force along the cell stacking direction of the thermal conductive layer 300 can be achieved more easily. In particular, to gradually change the adhesive force of the thermal conductive layer 300 according to its position, sequentially changing the composition of the thermal conductive layer 300 according to its position, or arranging various types of thermal conductive materials with different compositions according to their position, can be an inconvenient process. However, according to the above embodiments, a gradual change in the adhesive force of the thermal conductive layer 300 according to the position of the battery cell 110 can be easily realized without performing complex processes.

[0103] On the other hand, while some of the drawings in this specification have primarily described a configuration in which the thermal conductive layer 300 is located on the lower part of the battery module 10, the thermal conductive layer 300 may be located on other surfaces, such as the upper part of the battery module 10. Furthermore, the thermal conductive layer 300 may be located on two or more sides of the battery module 10. For example, the thermal conductive layer 300 may be applied to the upper and lower parts of the cell stack 100, respectively.

[0104] Figure 15 is a schematic perspective view of a battery pack containing a battery module according to one embodiment of the present invention.

[0105] Referring to Figure 15, a battery pack 1 according to one embodiment of the present invention may include one or more battery modules 10 according to one embodiment of the present invention as described above. The battery pack 1 according to the present invention may further include a BMS (Battery Management System) for integrated control of the charging and discharging of one or more battery modules, a current sensor, a fuse, etc., and a pack case 2 for housing such electrical components.

[0106] Alternatively, the battery pack 1 according to the present invention may include a battery module 10 according to the present invention but not a separate pack case 2, and the module case 200 of the battery module 10 may be configured to function as the pack case 2. In this case, the module case 200 may contain battery pack components such as a BMS, busbars, and relays. Such a form of battery pack is also called cell-to-pack (CTP) in that the battery cells 110 are directly housed in the pack case 2. Recently, development of such CTP-type battery packs has been increasing, and the present invention is also applicable to such CTP-type battery packs.

[0107] In particular, by providing a thermal conductive layer 300 with partially different adhesive strengths on the inner surface of the housing, which is both the pack case 2 and the module case 200, such as the bottom surface, stability against swelling can be ensured. Furthermore, the cooling performance of the multiple battery cells 110 is further improved by directly transferring heat to the pack case PC via the thermal conductive layer 300.

[0108] Figure 16 is a schematic perspective view of an automobile containing a battery pack according to one embodiment of the present invention.

[0109] Referring to Figure 16, an automobile 3 according to one embodiment of the present invention may include one or more battery packs 1 or battery modules 10 according to one embodiment of the present invention. The automobile 3 according to the present invention may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The automobile 3 includes four-wheeled vehicles and two-wheeled vehicles. The automobile 3 operates by receiving full power from the battery pack 1 or battery module 10 according to one embodiment of the present invention.

[0110] Although the present invention has been described above with reference to limited embodiments and drawings, it goes without saying that the present invention is not limited thereto, and that various modifications and variations are possible within the equivalent scope of the technical concept and claims of the present invention by persons with ordinary skill in the art to which the present invention belongs. [Explanation of Symbols]

[0111] 1 Battery Pack 2-pack case 3. Automobile 10 Battery Modules 100-cell stack 110 battery cells 111 Electrode Leads 200 Module Case 210 Case Body 220 Top Plate 230 End Plate 300 Thermal conductive layer 310 First thermal conductive layer 320 Second thermal conductive layer

Claims

1. A cell stack containing multiple battery cells, A module case configured to house the aforementioned cell stack, A battery module comprising a thermal conductive layer provided between the module case and the cell stack, configured such that the adhesive strength differs from the outside to the inside.

2. The battery module according to claim 1, characterized in that the heat conductive layer is configured such that the adhesive strength weakens as you move from the outside to the inside.

3. The aforementioned heat conductive layer is A first thermal conductive layer configured to contact the module case, The battery module according to claim 1, further comprising a second thermal conductive layer provided inside the first thermal conductive layer and configured to contact the cell laminate.

4. The battery module according to claim 3, characterized in that the first thermal conductive layer and the second thermal conductive layer are configured to have different adhesive strengths.

5. The battery module according to claim 3, characterized in that the adhesive force of the second thermal conductive layer is weaker than the adhesive force of the first thermal conductive layer.

6. The battery module according to claim 3, characterized in that the second thermal conductive layer is made of a material with a lower degree of hardening than the first thermal conductive layer.

7. The battery module according to claim 3, characterized in that the second thermal conductive layer is made of a material containing silicone.

8. The battery module according to claim 3, characterized in that the second heat conductive layer is configured to surround the end portion of the battery cell.

9. The battery module according to claim 8, characterized in that the second heat conduction layer is configured to be insertable between the plurality of battery cells when swelling occurs in the battery cells.

10. The battery module according to claim 8, characterized in that the first heat conductive layer is configured to contact the end portion of the battery cell.

11. The battery module according to claim 8, characterized in that the first heat conductive layer is configured to surround the end portion of the battery cell.

12. The battery module according to claim 3, characterized in that the thermal conductive layer is configured to include portions in which the thickness of the second thermal conductive layer differs as it progresses toward the outermost edge in the stacking direction of the battery cells.

13. A battery pack comprising a battery module according to any one of claims 1 to 12.

14. An automobile comprising a battery module according to any one of claims 1 to 12.

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