Battery pack and manufacturing method thereof, and automobile

Abstract

Provided is a battery pack in which the possibility of thermal runaway and the reduction of space efficiency are reduced by preventing rupture of the side portions of battery cells and ensuring structural rigidity within the battery module. The battery pack of the present invention includes a pack case, a battery cell assembly including a plurality of battery cells housed in the pack case, a resin layer that relatively fills the lower portion in the space between the plurality of battery cells, and an inorganic film that relatively fills the upper portion in the space between the plurality of battery cells.

Description

[Technical Field]

[0001] The present invention relates to a battery pack, and more particularly to a battery pack and a manufacturing method thereof, and a vehicle.

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0138104, filed on October 25, 2022, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings of that application. [Background technology]

[0003] Secondary batteries, which are easily applicable to various products and have electrical properties such as high energy density, are widely used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs) that are driven by electrical sources. These secondary batteries are attracting attention as a new energy source that is environmentally friendly and improves energy efficiency because they do not produce any by-products associated with energy use, in addition to their primary advantage of dramatically reducing the use of fossil fuels.

[0004] Currently, widely used types of secondary batteries include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries. The operating voltage of such unit secondary battery cells, i.e., unit battery cells, is approximately 2.5V to 4.5V. Therefore, if a higher output voltage is required, a battery pack may be configured by connecting multiple battery cells in series. Alternatively, a battery pack may be configured by connecting multiple battery cells in parallel depending on the required charge / discharge capacity of the battery pack. Therefore, the number of battery cells included in the battery pack can be variously set depending on the required output voltage and / or charge / discharge capacity.

[0005] Meanwhile, when a battery pack is constructed by connecting a plurality of battery cells in series / parallel, a battery module including at least one battery cell is first constructed, and then other components are added to the at least one battery module to construct the battery pack. Therefore, a conventional battery pack includes a plurality of battery cells, a module case that houses the battery cells in modular units, and a pack case that houses them.

[0006] In such conventional battery packs, for example, a battery pack including cylindrical battery cells has gaps between the battery cells housed in a module case, and the module case has a frame that fixes the battery cells. The gaps between the battery cells are either filled with ribs of the frame or left as empty space, and a battery pack is made up of a plurality of battery modules in which the battery cells and frames are combined.

[0007] However, in the case of conventional battery packs, when a cylindrical battery cell ignites, there is a possibility of a chain reaction due to vent fire and side rupture of adjacent battery cells. Also, since a module case is required in addition to the battery pack case and each battery module has multiple individual frames, the weight of the battery pack increases and the space efficiency within the battery pack decreases. In other words, there is a problem that fewer battery cells can be stored in a battery pack of the same size.

[0008] Therefore, there is a need for a solution that can provide a battery pack and a vehicle including the same that can reduce the possibility of chain fire and improve the problem of reduced space efficiency. Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention aims to provide a battery pack that reduces the possibility of chain fires and reduces loss of space efficiency by preventing rupture of the sides of battery cells and ensuring structural rigidity within the battery module.

[0010] Another object of the present invention is to provide a method for manufacturing such a battery pack.

[0011] It is yet another object of the present invention to provide a vehicle including such a battery pack. [Means for solving the problem]

[0012] In order to achieve the above object, a battery pack of the present invention includes a pack case, a battery cell assembly including a plurality of battery cells housed in the pack case, a resin layer filling a relatively lower portion of spaces between the plurality of battery cells, and an inorganic coating filling a relatively upper portion of spaces between the plurality of battery cells.

[0013] The inorganic coating is characterized by being more flame-retardant than the resin layer.

[0014] The battery cell may be a cylindrical battery cell, the battery cell may be housed upright in the pack case, and the resin layer and the inorganic coating may surround the side surfaces of the battery cell.

[0015] The resin layer and the inorganic coating are a double layer formed by forced phase separation during curing of a composition containing a base resin and an inorganic filler.

[0016] The inorganic filler has a lower density than the base resin.

[0017] The inorganic filler may be hollow glass beads.

[0018] The initial viscosity of the base resin is preferably 1000 cp or less.

[0019] In the composition, the content of the inorganic filler may be 10% or more.

[0020] The base resin may have a Shore hardness A of 80 or more and a Shore hardness D of 30 or more after hardening.

[0021] The base resin preferably has an initial hardening time of 30 minutes or more.

[0022] The pack case may further include an adhesive between an inner surface of the pack case and a lower end of the battery cell.

[0023] The battery cell may include a vent portion at the top or bottom, and the inorganic coating may surround the vent portion.

[0024] In a preferred example, the pack case includes a bottom frame or a pack tray that accommodates lower ends of the battery cells.

[0025] The pack case may further include a cover frame that covers an upper end of the battery cell.

[0026] In another preferred example, the pack case includes a base case that supports the battery cell assemblies, and cross beams that are provided on both sides of the base case and are coupled to upper ends of the battery cell assemblies.

[0027] The base case may further include an adhesive filled to a predetermined height on the inner surface of the base case.

[0028] In order to achieve the other object, a method for manufacturing a battery pack according to the present invention includes the steps of: accommodating a plurality of battery cells in a pack case; filling spaces between the plurality of battery cells with a composition including a base resin and an inorganic filler; and curing the composition to forcibly phase-separate the base resin and the inorganic filler due to a density difference during curing, thereby forming a resin layer that fills a relatively lower portion of the spaces between the plurality of battery cells and an inorganic coating that fills a relatively upper portion of the spaces between the plurality of battery cells.

[0029] In order to achieve the above-mentioned further object, the automobile of the present invention includes at least one battery pack of the present invention. [Effects of the Invention]

[0030] According to the present invention, it is possible to prevent the side rupture of the battery cells and ensure the structural rigidity within the battery module.

[0031] According to the present invention, the space between battery cells is filled with a resin layer, making it possible to omit a module case, and a method of forcibly phase-separating a composition containing a base resin and an inorganic filler while curing the composition can form a resin layer in the relatively lower portion of the space between the battery cells and an inorganic coating in the relatively upper portion of the space between the battery cells. The inorganic coating can ensure flame retardancy and reduce the possibility of chain fires.

[0032] According to the present invention, it is possible to provide a battery pack and a vehicle including the same that reduce the possibility of chain fires and the reduction in space efficiency.

[0033] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical concept of the present invention, so the present invention should not be interpreted as being limited to the matters described in the drawings. [Brief explanation of the drawings]

[0034] [Figure 1] 1 is a conceptual diagram of a battery pack according to an embodiment of the present invention. [Figure 2] FIG. 1 is a diagram illustrating phase separation. [Figure 3] 10A and 10B are diagrams illustrating a battery pack according to another embodiment of the present invention. [Figure 4] 4 is a diagram for explaining a battery cell included in the battery pack of FIG. 3. FIG. [Figure 5] 4 is a diagram for explaining a mechanism for ensuring safety when an abnormal situation occurs in the battery pack of FIG. 3. FIG. [Figure 6] 10A and 10B are diagrams illustrating a battery pack according to another embodiment of the present invention. [Figure 7] 7 is a diagram illustrating a battery cell assembly of the battery pack of FIG. 6. FIG. [Figure 8] FIG. 7 is a diagram for explaining the pack case of FIG. 6. [Figure 9] 1 is a diagram illustrating a vehicle according to an embodiment of the present invention; [Figure 10a] 1 is a photograph of the state of Comparative Example 1 after curing. [Figure 10b] 1 is a photograph showing a flame retardancy test of Comparative Example 1. [Figure 11a] 1 is a photograph of the state after curing of Comparative Example 2. [Figure 11b] 1 is a photograph showing the flame retardancy test of Comparative Example 2. [Figure 12a] 1 is a photograph of the state of an example after curing. [Figure 12b] 1 is a photograph showing a flame retardancy test of an example. DETAILED DESCRIPTION OF THE INVENTION

[0035] The present invention will become clearer by describing in detail preferred embodiments of the present invention with reference to the accompanying drawings. The embodiments described herein are illustrative to aid in understanding the invention, and it should be understood that the present invention can be implemented in various ways different from the embodiments described herein. Note that, to aid in understanding the invention, the accompanying drawings may be drawn not to scale, and some components may be exaggerated. In the drawings, the same reference numerals refer to the same elements.

[0036] FIG. 1 is a conceptual diagram of a battery pack according to one embodiment of the present invention.

[0037] Referring to FIG. 1, a battery pack A is composed of one or more battery modules B, and the battery module B may further be composed of a plurality of battery cells C.

[0038] In this embodiment, the types and structures of the battery pack A, battery module B, and battery cell C are not particularly limited. The battery pack A in this embodiment may include various types and structures of battery packs as long as they have a predetermined regular structure or shape and are coupled to the underside of a vehicle. Meanwhile, in this embodiment, the term "battery pack" is used for convenience of explanation, but this does not necessarily refer only to a battery pack in the encyclopedia sense. For example, the battery pack A in this embodiment may include technical concepts such as cell-to-pack (CTP) and cell-to-chassis (CTC). That is, in this embodiment, the term "battery pack A" may be interpreted to broadly include an energy storage means having a predetermined standardized structure or shape, coupled to a vehicle, and supplying power as a driving means.

[0039] The battery pack A includes a pack case A1. The pack case A1 accommodates a battery module B. The pack case A1 may have various configurations, as in other embodiments described below.

[0040] The battery module B may be a battery cell assembly in which a plurality of battery cells C are electrically connected in series and / or parallel. Alternatively, the battery module assembly may include other electrical components such as a battery management system (BMS). Conventional battery modules include a metal module case for housing the battery cells and providing mechanical rigidity, and a frame for securing the battery cells. Unlike conventional battery modules, the battery module B included in the battery pack A of this embodiment may be one in which the module case and frame are omitted or minimized.

[0041] Spaces exist between the plurality of battery cells C housed in the pack case A1 depending on the shape and housing method of the battery cells C. In this embodiment, a resin layer D is included in a relatively lower portion of the space between the battery cells C. Preferably, the resin layer D fills a relatively lower portion of the space between the battery cells C, so that no space exists between the battery cells C and the resin layer D. An inorganic coating E is included in a relatively upper portion of the space between the battery cells C. Preferably, the inorganic coating E fills a relatively upper portion of the space between the battery cells C, so that no space exists between the battery cells C and the inorganic coating E.

[0042] The resin layer D may be formed from the bottom of the pack case A1. The resin layer D may surround the bottom and side surfaces of the battery cells C. In another example, the resin layer D may be formed from the lower end of the battery cells C. The resin layer D may surround the side surfaces of the battery cells C except for the bottom surfaces. The resin layer D supports the battery cells C in place of the module case and frame of a conventional battery module, and in particular may play a role in mechanically protecting the side surfaces of the battery cells C. This can prevent side rupture of the battery cells C.

[0043] For example, the battery cell C may be a cylindrical battery cell. The battery cell C may be housed upright in the pack case A1. The resin layer D and the inorganic coating E may surround the side surfaces of the battery cell C to mechanically support it.

[0044] The inorganic coating E may be formed above the resin layer D. The inorganic coating E may surround the top and side surfaces of the battery cells C. In another example, the inorganic coating E may surround only the side surfaces of the battery cells C. The inorganic coating E may be formed to fill the top surface of the pack case A1. The resin layer D may surround the side surfaces of the battery cells C except for the bottom surfaces. The resin layer D supports the battery cells C in place of the module case and frame of a conventional battery module, and in particular may play a role in mechanically protecting the side surfaces of the battery cells C. The inorganic coating E may have flame retardancy compared to the resin layer D. The inorganic coating E can ensure the flame retardancy of the battery pack A compared to when the interior of the battery pack A is completely filled with a resin layer.

[0045] The concept of "relative" varies depending on the reference. In this embodiment, the bottom surface of the pack case A1 is used as the reference. That is, "relatively lower" refers to the side closer to the bottom of the pack case A1. A resin layer D and an inorganic coating E are formed between multiple battery cells C in the height direction, which is perpendicular to the bottom surface of the pack case A1 and extends upward. The spaces between the battery cells C in the height direction can be filled without gaps with the resin layer D and the inorganic coating E. There is discontinuity between the materials filling the spaces between the battery cells C in the height direction. The resin layer D is included on one side along the height direction, and the inorganic coating E is included on the other side.

[0046] After a plurality of battery cells C are first housed in the pack case A1, a resin layer D and an inorganic coating E may be formed in the spaces between the battery cells C. In this case, as shown in FIG. 1, the resin layer D may be formed on the side closer to the bottom surface of the pack case A1, and the inorganic coating E may be formed on top of the resin layer D in the height direction.

[0047] In another example, a plurality of battery cells C may be housed in the pack case A1 after first forming a resin layer D and an inorganic coating E in the spaces between them on the outside of the pack case A1. In this case, the heightwise positions of the resin layer D and the inorganic coating E may vary along the direction in which the plurality of battery cells C are housed in the pack case A1. For example, when the side on which the resin layer D is formed is housed in the pack case A1 at the bottom, the resin layer D may be located closer to the bottom of the pack case A1, and the inorganic coating E may be located above the resin layer D in the heightwise direction, as shown in FIG. 1 . Conversely, when the side on which the inorganic coating E is formed is housed in the pack case A1 at the bottom, the inorganic coating E may be located closer to the bottom of the pack case A1, and the resin layer D may be located above the inorganic coating E in the heightwise direction.

[0048] In particular, the resin layer D and the inorganic coating E are double layers formed by forced phase separation during curing of a composition containing a base resin and an inorganic filler. This has the advantage that the process of forming the resin layer D and the process of forming the inorganic coating E do not need to be performed separately. In addition, the inclusion of an inorganic filler not only enables the battery pack A to be made lighter, but also has the advantage of contributing to a reduction in manufacturing costs by allowing for the use of less of the relatively expensive base resin.

[0049] Forced phase separation of the composition can be used to position the inorganic coating E in areas where greater flame retardancy is required in the height direction. For example, if a vent is formed at the upper end of the battery cell C, the inorganic coating E can be formed to be positioned at the upper end of the battery cell C so as to surround the vent. Conversely, if a vent is formed at the lower end of the battery cell C, the inorganic coating E can be formed to be positioned at the lower end of the battery cell C so as to surround the vent. If forced phase separation of the composition is used with the battery cell C positioned so that its lower end faces upward, the inorganic coating E can be formed on the lower end side of the battery cell C. The inorganic coating E can more effectively block heat transfer to the surrounding area when an abnormal condition occurs in the battery cell C.

[0050] The resin layer D may be formed to a thickness of ½ or less based on the height of the battery cell C, and the inorganic coating E may be formed to a thickness of ½ or more. In another example, the resin layer D may be formed to a thickness of ⅔ or less based on the height of the battery cell C, and the inorganic coating E may be formed to a thickness of ⅓ or more based on the height of the battery cell C. In yet another example, the resin layer D may be formed to a thickness of ⅘ or less based on the height of the battery cell C, and the inorganic coating E may be formed to a thickness of ⅕ or more based on the height of the battery cell C. The greater the thickness of the resin layer D than the thickness of the inorganic coating E based on the height of the battery cell C, the more advantageous it is in terms of ensuring mechanical rigidity. The thickness of the inorganic coating E is preferably smaller than the thickness of the resin layer D but greater than the minimum thickness required to achieve flame retardancy.

[0051] The base resin preferably has a Shore hardness A of 80 or more and a Shore hardness D of 30 or more after curing. Shore hardness A is well known as a measure of the hardness of soft rubber, and Shore hardness D is well known as a measure of the hardness of hard rubber. Shore hardness A and Shore hardness D have values ​​between 0 and 100. Products with a Shore hardness A of 80 or more and a Shore hardness D of 30 or more fall into the hard and extra hard categories on the well-known Shore hardness scale. For example, tires, shoe heels, and cart wheels fall into the hard category, and safety helmets fall into the extra hard category. If the base resin has a Shore hardness A of 80 or more after hardening and a Shore hardness D of 30 or more, the rigidity of the resin layer D can be ensured to provide sufficient mechanical support for the battery cells C, and the mechanical rigidity of the battery pack A can be ensured without the need for a module case or frame.

[0052] Examples of the base resin include epoxy and urethane, and epoxy is preferred for the purpose of ensuring rigidity.

[0053] Epoxy and urethane are not flame-retardant, so additional flame-retardant supplements are required. In the field of conventional battery packs, when epoxy or urethane is used as a potting agent, phosphorus-based flame retardants or flame-retardant fillers are sometimes added and uniformly dispersed. However, these phosphorus-based flame retardants and flame-retardant fillers can increase the cost and weight.

[0054] The inorganic filler is preferably a hollow glass bead. Hollow glass beads have a lower density than phosphorus-based flame retardants and flame-retardant fillers, and are flame-retardant. They are also advantageous in terms of weight reduction and cost.

[0055] The present invention is characterized in that the inorganic filler is not uniformly dispersed in the base resin and then cured, but rather, forced phase separation of the mixture due to density differences is used to collect the base resin on one side and the inorganic filler on the other side, and then cured.

[0056] FIG. 2 is a diagram for explaining phase separation in more detail.

[0057] 2a shows the state of composition F containing base resin F1 and inorganic filler F2 before curing. When composition F is produced by mixing base resin F1 and inorganic filler F2, inorganic filler F2 is uniformly dispersed within base resin F1 before curing.

[0058] Figure 2b shows a state in which the inorganic filler F2, which has a lower density, is concentrated at the top due to density differences, and the base resin F1 is mainly located below it.

[0059] Composition F, which contains base resin F1 and inorganic filler F2, undergoes phase separation over time due to differences in density. The inorganic filler F2, which has a lower density, gathers relatively at the top to form the upper layer, while base resin F1 gathers relatively at the bottom to form the lower layer. When cured in this state, a resin layer D is formed from the base resin F1 that has gathered relatively at the bottom, and an inorganic coating E is formed from the inorganic filler F2 that has gathered relatively at the top. Curing can be thermal curing, UV curing, or natural curing, depending on the properties of the base resin.

[0060] In this way, after the base resin F1 is completely cured, an inorganic coating E containing mainly the inorganic filler F2 is formed in the relatively upper part, and a resin layer D containing mainly the base resin F1 is formed in the relatively lower part.

[0061] Such phase separation can be used to manufacture the battery pack A according to the present invention.

[0062] The manufacturing method of the battery pack A may be performed as follows.

[0063] First, a plurality of battery cells C are housed in a pack case A1. The spaces between the plurality of battery cells C are filled with a composition F containing a base resin F1 and an inorganic filler F2.

[0064] When the composition F is cured, as described in FIG. 2, the base resin F1 and the inorganic filler F2 are forced to phase separate due to the density difference during curing, thereby forming a resin layer D that fills the lower part of the space between the plurality of battery cells C, and an inorganic coating E that fills the upper part of the space between the plurality of battery cells C.

[0065] If the base resin F1 is cured while the inorganic filler F2 is uniformly dispersed in it, the content of the inorganic filler F2 must be increased to ensure the desired level of flame retardancy. Increasing the content of the inorganic filler F2 requires decreasing the content of the base resin F1, which is undesirable in terms of ensuring rigidity.

[0066] In the present invention, the flame-retardant inorganic filler F2 is concentrated on one side to form the inorganic coating E, thereby ensuring flame retardancy particularly in the area where the inorganic coating E is located. This has the effect of ensuring a desired level of flame retardancy with a smaller amount of inorganic filler F2 than when the inorganic filler F2 is uniformly dispersed in the base resin F1 and cured.

[0067] To manufacture battery pack A, it is necessary to select the initial viscosity and initial curing time of base resin F1 to facilitate phase separation. Also, the content of inorganic filler F2 (which determines the thickness of the inorganic coating) must be determined to ensure flame retardancy.

[0068] The initial viscosity of the base resin F1 is preferably 1000 cp or less. The initial viscosity is the viscosity before gelation begins. If the initial viscosity is greater than 1000 cp, even if a low-density inorganic filler F2 is used, the inorganic filler F2 will have difficulty moving above the base resin F1, making complete phase separation less likely, and increasing the likelihood that the inorganic filler F2 will harden in a uniformly dispersed state within the base resin F1. If the initial viscosity is too low, the hardening time may be prolonged or the resin layer D may not have sufficient hardness. The initial viscosity of the base resin F1 is determined taking these factors into consideration. The initial viscosity of the base resin F1 can be adjusted by the type of base resin F1, the molecular weight of the base resin F1, additives such as viscosity modifiers, etc.

[0069] The base resin F1 preferably has an initial curing time of 30 minutes or more. The initial curing time is the time until gelation begins. During the initial curing time, the inorganic filler F2 migrates to the top, allowing sufficient phase separation to occur. If the initial curing time is too short, complete phase separation may be difficult to achieve. If the initial curing time is too long, the overall process time increases, which is undesirable from the perspective of productivity. The initial curing time of the base resin F1 is determined taking these factors into consideration. The initial curing time of the base resin F1 can be adjusted depending on the type of the base resin F1, the molecular weight of the base resin F1, or additives such as curing agents that assist gelation.

[0070] The content of the inorganic filler F2 in the composition F may be 10% or more. This content is expressed as a percentage of the volume of the inorganic filler F2 relative to the total volume of the composition F. 10% may be the minimum content at which flame retardancy can be ensured. The higher the content of the inorganic filler F2, the higher the flame retardancy and the lower the content of the base resin F1, which is advantageous in terms of cost. However, if the content of the inorganic filler F2 is too high, complete phase separation may be hindered, which may be disadvantageous in terms of ensuring mechanical rigidity. The content of the inorganic filler F2 is determined taking these factors into consideration.

[0071] As described above, by filling the spaces between the battery cells C in the battery pack A with a resin layer D having hard physical properties, structural rigidity can be ensured. The resin layer D can replace a frame or a module case with ribs. This is advantageous for reducing the weight of the battery pack A, and does not reduce the space efficiency within the battery pack A. In other words, even in a battery pack of the same size, more battery cells can be placed in it than before, thereby increasing the energy density.

[0072] By using forced phase separation of composition F, which is a mixture of base resin F1 capable of forming resin layer D and inorganic filler F2, it is possible to form resin layer D and inorganic coating E in the same process step. Inorganic coating E is formed by forced phase separation of composition F, and can ensure flame retardancy. Inorganic coating E complements the flame retardancy of resin layer D.

[0073] As mentioned above, the pack case A1 can be embodied in various ways, which will be described in detail below with reference to the examples.

[0074] FIG. 3 is a diagram illustrating a battery pack according to another embodiment of the present invention.

[0075] Referring to FIG. 3 , the battery pack 10 may include a battery cell assembly 100 , a resin layer 200 , an inorganic coating 250 , a pack case 300 , and an adhesive 400 .

[0076] The battery cell assembly 100 may include a plurality of battery cells 110 .

[0077] FIG. 4 is a diagram for explaining a battery cell included in the battery pack of FIG.

[0078] The battery cell 110 is a secondary battery and may be cylindrical, pouch-shaped, or rectangular. Hereinafter, in this embodiment, the battery cell 110 will be described as being cylindrical.

[0079] A vent portion 115 for discharging gases, flames, etc. may be provided at the top of each battery cell 110. The vent portion 115 may be formed thinner at the top of the battery cell 110 than the surrounding area. This is because, when an abnormal situation occurs in the battery cell 110 and the internal pressure increases above a certain level, the vent portion 115 ruptures, thereby more easily discharging the gases and flames to the outside of the battery cell 110.

[0080] The vent 115 may be provided as an opening or notch of a predetermined size, or may be formed as a structure in which a film that breaks when pressure exceeds a certain level is added to the opening of the predetermined size.

[0081] An insulating tube 118 may be provided on the outer circumferential surface of each battery cell 110. The insulating tube 118 is for insulating the battery cell 110 and may cover the outer circumferential surface of the battery cell 110. Thus, a plurality of insulating tubes 118 may be provided corresponding to the number of battery cells 110. Such insulating tubes 118 may be provided as shrink tubes.

[0082] The battery cells 110 may be connected by, for example, wire bonding.

[0083] As shown in FIG. 3 , the battery cell assembly 100 is housed in a pack case 300. A resin layer 200 may be filled between the plurality of battery cells 110 of the battery cell assembly 100. This resin layer 200 may be the same as the resin layer D in the above-described embodiment, and therefore, a redundant description will be omitted. The resin layer 200 fills a relatively lower portion of the space between the plurality of battery cells 110. The resin layer 200 may ensure structural rigidity. In this case, a frame or module case with ribs may not be used. This is advantageous for reducing the weight of the battery pack 10, and does not reduce the space efficiency of the battery pack 10.

[0084] An inorganic coating 250 may also be filled between the plurality of battery cells 110 of the battery cell assembly 100. Such an inorganic coating 250 may be the same as the inorganic coating E in the above-described embodiment, and therefore a duplicated description will be omitted. The inorganic coating 250 fills the relatively upper portion of the space between the plurality of battery cells 110. The inorganic coating 250 surrounds the vent portion 115. The inorganic coating 250 has a thickness that extends to the bottom of the vent portion 115, based on the height of the battery cell 110. The inorganic coating 250 is flame-retardant, and therefore can respond to the outbreak of a flame at the vent portion 115.

[0085] The pack case 300 may accommodate the battery cell assembly 100, the resin layer 200, and the inorganic coating 250. To this end, the pack case 300 may be provided with an accommodation space capable of accommodating the battery cell assembly 100, the resin layer 200, and the inorganic coating 250.

[0086] Specifically, the pack case 300 of this embodiment includes a bottom frame 305 (or pack tray) that accommodates the lower ends of the battery cells 110. The pack case 300 may further include a cover frame (not shown) that covers the upper ends of the battery cells 110.

[0087] The bottom frame 305 may support the battery cell assembly 100. To this end, the bottom frame 305 may have a predetermined area capable of supporting the battery cell assembly 100. Also, grooves 305a may be formed so that the lower ends of the battery cells 110 can be inserted. By directly inserting the battery cells 110 into the bottom frame 305, the frame can be minimized, increasing space efficiency and contributing to improved energy density. A cell-to-pack (CTP) structure may be implemented.

[0088] 3, the adhesive 400 is provided at a predetermined height in the pack case 300 and partially fills the grooves 305a. The adhesive 400 further firmly fixes the battery cells 110 inserted in the grooves 305a. The adhesive 400 may at least partially cover the lower ends of the battery cell assemblies 100.

[0089] A method for manufacturing such a battery pack 10 will be specifically described below.

[0090] A manufacturer or the like may store the battery cells 110 in the pack case 300. For example, the battery cell assembly 100 may be fixed in the pack case 300 filled with adhesive 400. Thereafter, the battery cells 110 may be electrically connected to each other by wire bonding or the like.

[0091] In another example, the battery cells 110 may be electrically connected first outside the pack case 300 , and then the battery cell assembly 100 may be housed inside the pack case 300 filled with the adhesive 400 .

[0092] As in the previous embodiment, the space between the battery cells 110 is filled with a composition containing a base resin and an inorganic filler.

[0093] When the composition is cured, the base resin and the inorganic filler are forced to undergo phase separation due to the density difference during curing, thereby forming the resin layer 200 and the inorganic coating 250 .

[0094] As described above, the battery pack 10 according to this embodiment embodies a flame retardant and mechanical support structure through adhesive bonding using the resin layer 200, inorganic coating 250, and adhesive 400, etc., thereby further simplifying the process. Since the battery pack 10 is embodied through an integrated adhesive bonding structure of the battery cells 110, rather than a structure in which the battery cells 110 are bonded to a frame or module case by an interference fit, the efficiency of the assembly process can be significantly improved and the possibility of leakage can be significantly reduced compared to a structure in which individual battery cells are bonded.

[0095] Hereinafter, a mechanism for ensuring safety in the battery pack 10 according to this embodiment when an abnormal situation such as overheating occurs will be specifically described.

[0096] FIG. 5 is a diagram for explaining a mechanism for ensuring safety when an abnormal situation occurs in the battery pack of FIG.

[0097] 5, an abnormal condition such as overheating may occur in any one of the battery cells 110 in the battery pack 10, generating gas or flames. In this case, the gas or flames 405 can be quickly released through the vent 115 of the battery cell 110 where the abnormal condition has occurred.

[0098] In addition, in this embodiment, the inorganic coating 250 is filled while surrounding the vent portion 115 of the battery cell 110, and such inorganic coating can effectively prevent the spread of a flame 405 or the like to the battery cell 110 adjacent to the battery cell 110 in which the vent portion 115 is opened due to an abnormal situation, thereby reducing the possibility of a chain fire.

[0099] Meanwhile, since the inorganic coating 250 is basically brittle, when the flame 405 or the like occurs, the flame 405 or the like can quickly escape to the outside of the battery pack 10 before spreading to the adjacent battery cells 110 around the battery cell 110 where the abnormal situation occurred.

[0100] Therefore, the battery pack 10 according to this embodiment can further ensure the safety of the battery pack 10 by preventing explosions such as thermal runaway caused by chain fires when an abnormal situation occurs.

[0101] Furthermore, if an abnormal situation 410 occurs on the side of the battery cell 110, the resin layer 200 located on the side can prevent side rupture.

[0102] FIG. 6 is a diagram illustrating a battery pack according to another embodiment of the present invention.

[0103] 6, the battery pack 20 may include a battery cell assembly 100, a resin layer 200, an inorganic coating 250, a pack case 310, and an adhesive 420. Because the battery pack 20 according to this embodiment is similar to the battery pack 10 according to the previous embodiment, redundant descriptions of configurations that are substantially the same as or similar to those of the previous embodiment will be omitted, and the following description will focus on differences from the previous embodiment.

[0104] FIG. 7 is a diagram illustrating a battery cell assembly of the battery pack of FIG.

[0105] The battery cell assembly 100 may include a plurality of battery cells 110 and a bus bar assembly 150 .

[0106] The battery cell assembly 100 may include a first case (not shown) that supports one side, for example, the upper side, of the battery cell 110. The battery cell assembly 100 may include a second case (not shown) that supports the other side, for example, the lower side, of the battery cell 110. The first case and the second case may not be included.

[0107] When the first and second cases are included, they may be made of a plastic material. When the first and second cases are included, they may be coupled to the pack case 310. For example, they may be coupled by adhesive bonding, such as with an adhesive, to simplify the assembly process.

[0108] The bus bar assembly 150 may be electrically connected to the battery cells 110. The bus bar assembly 150 may be connected to the battery cells 110 by laser welding, wire bonding, or the like. The bus bar assembly 150 may be electrically connected to the battery cells 110 on the upper side or the lower side of the battery cell assembly 100. In this embodiment, an example in which the bus bar assembly 150 is connected to the lower side of the battery cell assembly 100 is given.

[0109] The pack case 310 may accommodate the battery cell assembly 100, the resin layer 200, and the inorganic coating 250. To this end, the pack case 310 may be provided with an accommodation space capable of accommodating the battery cell assembly 100, the resin layer 200, and the inorganic coating 250.

[0110] FIG. 8 is a diagram for explaining the pack case of FIG.

[0111] Referring to FIG. 8, the pack case 310 may include a base case 320 and a cross beam 330 .

[0112] The base case 320 may support the battery cell assembly 100. To this end, the base case 320 may have a predetermined area for supporting the battery cell assembly 100.

[0113] The cross beams 330 may be provided on both sides of the base case 320 and may be coupled to the upper end of the battery cell assembly 100. For example, if the first case is included, the cross beams 330 may be coupled to both ends of the first case.

[0114] The cross beam 330 absorbs or buffers external impacts applied from outside the pack case 310, and can prevent the impacts from being transmitted to the battery cells 110 inside the pack case 310.

[0115] With further reference to FIG. 6 , the adhesive 420 may be provided at a predetermined height within the pack case 310 and may at least partially cover the lower ends of the battery cell assemblies 100 .

[0116] Specifically, the adhesive 420 may be provided to fill the inner surface of the base case 320 to a predetermined height. The lower portions of the battery cells 110 and the bus bar assemblies 150 of the battery cell assembly 100 may be immersed in the adhesive 420.

[0117] In this embodiment, the battery cell assembly 100 can be fixed in the pack case 310 by the adhesive 420, and if a waterproof adhesive is used as the adhesive 420, the waterproofing process can be further simplified, reducing manufacturing costs and improving waterproof reliability.

[0118] A method for manufacturing such a battery pack 20 will be described in more detail below.

[0119] A manufacturer may first manufacture the battery cell assembly 100 by arranging the battery cells 110 and then connecting the bus bar assembly 150. For example, the bus bar assembly 150 and the battery cells 110 may be electrically connected to each other by laser welding, wire bonding, or the like.

[0120] Thereafter, the battery cell assembly 100 may be fixed in the pack case 310 filled with adhesive 420 , and the battery cells 110 may be housed in the pack case 310 .

[0121] As described in the above-mentioned embodiment, a composition containing a base resin and an inorganic filler is filled into the space between the battery cells 110, and during curing, the density difference causes forced phase separation between the base resin and the inorganic filler, thereby forming the resin layer 200 and the inorganic coating 250.

[0122] As described above, the battery pack 20 according to this embodiment embodies waterproof, flame-retardant, and mechanical support structures through adhesive bonding using the resin layer 200, inorganic coating 250, and adhesive 420, etc., thereby simplifying the manufacturing process.

[0123] FIG. 9 is a diagram illustrating a vehicle according to an embodiment of the present invention.

[0124] 9, the automobile 1 is an electric vehicle or a hybrid vehicle and may include at least one of the battery packs A, 10, and 20 according to the above-described embodiments as an energy source. Since the automobile 1 according to this embodiment includes the battery packs A, 10, and 20, it may have all the advantages of the battery packs A, 10, and 20.

[0125] Through the various embodiments described above, it is possible to provide a battery pack A, 10, 20 and an automobile 1 including the same, which reduce the possibility of chain fires and the reduction in space efficiency.

[0126] The present invention will be explained in more detail below by way of experimental examples.

[0127] We checked the flame retardancy and phase separation depending on the viscosity of the base resin. We conducted the experiment using a base resin with an initial curing time of 30 minutes or more, which is sufficient for phase separation to occur.

[0128] Fig. 10a is a photograph of the state of Comparative Example 1 after curing, and Fig. 10b is a photograph of the flame retardancy test of Comparative Example 1. Fig. 11a is a photograph of the state of Comparative Example 2 after curing, and Fig. 11b is a photograph of the flame retardancy test of Comparative Example 2.

[0129] In Comparative Examples 1 and 2, an epoxy resin with an initial viscosity of 2000 cp was used as the base resin.

[0130] Comparative Example 1 is a sample in which only the base resin is cured without the low-density filler. As shown in Figure 10a, this sample consists of only a resin layer. Referring to Figure 10b, it can be seen that this sample sustained a flame during a flame retardancy test. It is difficult to expect flame retardancy from the base resin alone.

[0131] In Comparative Example 2, 10% hollow glass beads were mixed into the base resin and cured. Referring to Figure 11a, it can be seen from the outer surface and cross section of the sample that no phase separation occurred. As shown in Figure 11b, this sample sustained flame during the flame retardancy test. Therefore, even if hollow glass beads are included, adequate flame retardancy cannot be ensured unless phase separation occurs. The reason for the lack of phase separation is that the initial viscosity of the base resin was high.

[0132] FIG. 12a is a photograph of the example in its post-cured state, and FIG. 12b is a photograph of the example after flame retardancy testing.

[0133] The epoxy resin of the example, with an initial viscosity of 1000 cp, was used as the base resin, and 10% hollow glass beads were mixed and cured. Referring to Figure 12a, complete phase separation was confirmed from the outer surface and cross section of the sample. A layer F2' of hollow glass beads, which had been phase-separated and gathered, can be seen in the upper layer. Furthermore, the hollow glass bead layer F2' is continuous in both the vertical and horizontal directions of the sample, confirming its role as an inorganic coating. When the phase-separated portion, i.e., the hollow glass bead layer F2', was heated with a torch, the fire was extinguished within 10 seconds after heating, as shown in Figure 12b. This demonstrates sufficient flame retardancy.

[0134] When inorganic filler is mixed into a base resin with a specific initial viscosity of 1000 cp or less and an initial curing time of 30 minutes or more, it has been confirmed that separation of the mixture occurs due to differences in density before curing (phase separation). When inorganic filler is mixed at 10% or more, a thicker upper inorganic coating is formed due to phase separation, which is advantageous in ensuring flame retardancy. The content of inorganic filler in the composition varies depending on the structure of the battery pack, and the higher the content of inorganic filler, the more advantageous it is in terms of ensuring flame retardancy and price competitiveness. At current laboratory levels, it has been confirmed that flame retardancy can be ensured even with inorganic filler at the 10% level.

[0135] As described above, the present invention has been described using limited examples and drawings, but the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary skill in the art to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims. [Explanation of symbols]

[0136] A, 10, 20 battery pack A1, 300, 310 pack case B Battery module C Battery Cell D, 200 resin layers E, 250 inorganic coating F Composition F1 base resin F2 Inorganic filler F2' Hollow glass bead layer 1. Automobiles 100 Battery Cell Assembly 115 Vent 150 Busbar Assembly 305 bottom frame 320 Base Case 330 Cross Beam 400, 420 adhesive

Claims

1. Pack case and a battery cell assembly including a plurality of battery cells housed in the pack case; a resin layer filling a relatively lower portion of spaces between the plurality of battery cells; an inorganic coating that relatively fills the upper portion of spaces between the battery cells; Including the battery pack.

2. The battery pack according to claim 1 , wherein the inorganic coating has a higher flame retardancy than the resin layer.

3. 2. The battery pack according to claim 1, wherein the battery cells are cylindrical battery cells, the battery cells are housed upright in the pack case, and the resin layer and the inorganic coating surround the sides of the battery cells.

4. 2. The battery pack according to claim 1, wherein the resin layer and the inorganic coating are a double layer formed by forced phase separation during curing of a composition including a base resin and an inorganic filler.

5. The battery pack according to claim 4 , wherein the inorganic filler has a lower density than the base resin.

6. The battery pack according to claim 4 , wherein the inorganic filler is a hollow glass bead.

7. The battery pack according to claim 4, wherein the base resin has an initial viscosity of 1000 cp or less.

8. The battery pack according to claim 4 , wherein the content of the inorganic filler in the composition is 10% or more.

9. The battery pack according to claim 4, wherein the base resin has a Shore hardness A of 80 or more and a Shore hardness D of 30 or more after hardening.

10. The battery pack according to claim 4 , wherein the base resin has an initial curing time of 30 minutes or more.

11. The battery pack according to claim 1 , further comprising an adhesive between the inner surface of the pack case and the battery cell.

12. The battery pack according to claim 1 , wherein the battery cell includes a vent portion at the top or bottom, and the inorganic coating surrounds the vent portion.

13. The battery pack according to claim 1 , wherein the pack case includes a bottom frame or a pack tray that houses lower ends of the battery cells.

14. The battery pack according to claim 13 , wherein the pack case further comprises a cover frame that covers an upper end of the battery cell.

15. The pack case is a base case supporting the battery cell assembly; cross beams provided on both sides of the base case and coupled to upper ends of the battery cell assemblies; 10. The battery pack of claim 1, comprising:

16. The battery pack according to claim 15, further comprising an adhesive agent filled to a predetermined height on the inner surface of the base case.

17. storing a plurality of battery cells in a pack case; Filling spaces between the plurality of battery cells with a composition including a base resin and an inorganic filler; curing the composition, forcibly phase-separating the base resin and the inorganic filler due to a density difference during curing, thereby forming a resin layer that fills a relatively lower portion of the space between the plurality of battery cells and an inorganic coating that fills a relatively upper portion of the space between the plurality of battery cells; A method for manufacturing a battery pack, comprising:

18. The method for manufacturing a battery pack according to claim 17, wherein the inorganic coating has higher flame retardancy than the resin layer.

19. The method for manufacturing a battery pack according to claim 17, wherein the base resin has an initial viscosity of 1000 cp or less.

20. The method of manufacturing a battery pack according to claim 17, wherein the content of the inorganic filler in the composition is 10% or more.

21. The method for manufacturing a battery pack according to claim 17, wherein the base resin has a Shore hardness A of 80 or more and a Shore hardness D of 30 or more after hardening.

22. The method for manufacturing a battery pack according to claim 17, wherein the base resin has an initial curing time of 30 minutes or more.

23. A motor vehicle comprising at least one battery pack according to any one of claims 1 to 16.

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