Battery pack, method for manufacturing the same, and motor vehicle

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, a method for manufacturing the same, and an automobile.

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0138104 filed on October 25, 2022, and all of the contents disclosed in the specification and drawings of the application are incorporated herein by reference.

Background Art

[0003] Secondary batteries that are easily applicable 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 (EVs) or hybrid electric vehicles (HEVs) driven by an electric drive source. Such secondary batteries are attracting attention as a new energy source for improving energy efficiency because they are environmentally friendly not only in terms of the primary advantage of significantly reducing the use of fossil fuels but also in that no by-products are generated during energy use.

[0004] Currently, widely used types of secondary batteries include lithium-ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel metal hydride batteries, nickel zinc batteries, etc. The operating voltage of such a unit secondary battery cell, i.e., a unit battery cell, is about 2.5V to 4.5V. Therefore, when a higher output voltage is required, a plurality of battery cells can be connected in series to form a battery pack. Also, a plurality of battery cells may be connected in parallel to form a battery pack according to the charge and discharge capacity required for the battery pack. Therefore, the number of battery cells included in the battery pack can be variously set according to the required output voltage and / or charge and discharge capacity.

[0005] On one hand, when configuring a battery pack by connecting a plurality of battery cells in series / parallel, it is common to first configure a battery module including at least one battery cell, and then use such at least one battery module to add other components to configure the battery pack. Therefore, a conventional battery pack generally includes a plurality of battery cells, a module case for housing the battery cells in module units, and a pack case for housing these components.

[0006] In such a conventional battery pack, for example, in the case of a battery pack including cylindrical battery cells, there is a gap between the battery cells housed in the module case, and there is a frame for fixing the battery cells in the module case. The gap between the battery cells is filled with the ribs of the frame or remains as an empty space, and a plurality of battery modules in which the battery cells and the frame are combined gather to form the battery pack.

[0007] However, in the case of a conventional battery pack, when a cylindrical battery cell catches fire, there is a possibility of chain fire due to the ignition of the vent part and the side rupture of the adjacent battery cell. In addition to the battery pack case, a module case is also required, and since there are a plurality of individual frames in each battery module, the weight of the battery pack increases, and there is a problem that the space efficiency in the battery pack decreases. That is, even for battery packs of the same size, there is a problem that fewer battery cells can be housed.

[0008] Therefore, there is a need for a solution that can provide a battery pack with reduced possibility of chain fire and improved problem of reduced space efficiency, and an automobile including the same.

Summary of the Invention

Problems to be Solved by the Invention

[0009] The present invention aims to provide a battery pack with reduced likelihood of thermal runaway and reduced degradation of space efficiency by preventing rupture of the side portions 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] Yet another object of the present invention is to provide a motor vehicle including such a battery pack.

Means for Solving the Problems

[0012] To achieve the above problems, 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 part in the space between the plurality of battery cells, and an inorganic coating that relatively fills the upper part in the space between the plurality of battery cells.

[0013] The inorganic coating is characterized by having higher flame retardancy than the resin layer.

[0014] The battery cell is a cylindrical battery cell, the battery cell is vertically housed in the pack case, and the resin layer and the inorganic coating can surround the side surface of the battery cell.

[0015] The resin layer and the inorganic coating are a double layer formed by forcibly phase-separating while a composition including a base resin and an inorganic filler is cured.

[0016] The inorganic filler is lower in density than the base resin.

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

[0018] It is desirable that the initial viscosity of the base resin is 1000 cp or less.

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

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

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

[0022] An adhesive may be further included between the inner surface of the pack case and the lower end of the battery cell.

[0023] The battery cell includes a vent portion at the upper or lower part, and the inorganic coating may surround the vent portion.

[0024] In a desirable example, the pack case includes a bottom frame or a pack tray that houses the lower end of the battery cell.

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

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

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

[0028] In addition, the method for manufacturing a battery pack according to the present invention for achieving the above other object includes a step of housing a plurality of battery cells in a pack case, a step of filling a space between the plurality of battery cells with a composition containing a base resin and an inorganic filler, and a step of curing the composition. During the curing process, the base resin and the inorganic filler are forcibly phase-separated by a density difference, thereby forming a resin layer that relatively fills the lower part in the space between the plurality of battery cells and an inorganic film that relatively fills the upper part in the space between the plurality of battery cells.

[0029] The automobile of the present invention for achieving still another object includes at least one battery pack according to the present invention.

Advantages of the Invention

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

[0031] According to the present invention, the space between battery cells can be filled with a resin layer to enable omission of a module case, and by a method of forcibly phase-separating a composition containing a base resin and an inorganic filler while curing the composition, the lower part in the space between battery cells can be formed as a resin layer and the upper part in the space between battery cells can be formed as an inorganic film. The inorganic film can ensure flame retardancy and reduce the possibility of chain ignition.

[0032] According to the present invention, it is possible to provide a battery pack and an automobile including the same in which the possibility of chain ignition and the reduction of space efficiency are decreased.

[0033] The following drawings attached to this 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

[0034]

Figure 1

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Figure 10a

Figure 10b

Figure 11a

Figure 11b

Figure 12a

Figure 12b

Modes for Carrying Out the Invention

[0035] The present invention will become clearer by explaining in detail the preferred embodiments of the present invention with reference to the accompanying drawings. The embodiments described herein are shown by way of example to assist in the understanding of the invention, and it must be understood that the present invention can be implemented in various ways different from the embodiments described herein. For the purpose of assisting in the understanding of the invention, the accompanying drawings may show some components exaggerated rather than at actual scale. In the drawings, the same reference numerals denote the same elements.

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

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

[0038] In this embodiment, the types and structures of the battery pack A, the battery module B, and the battery cell C are not particularly limited. The battery pack A of this embodiment can include battery packs of various types and structures as long as it has a predetermined shaped structure and shape and is coupled to the lower part of the vehicle. On the other hand, 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 dictionary sense. For example, the battery pack A of 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" can be interpreted in a broad sense to include energy storage means having a predetermined standardized structure and shape and coupled to the vehicle to supply electric power as a driving means.

[0039] The battery pack A includes a pack case A1. The battery module B is housed inside the pack case A1. The pack case A1 can be configured in various ways as in other embodiments described later.

[0040] The battery module B can be a concept of a battery cell assembly in which a plurality of battery cells C are electrically connected in series and / or in parallel. Or, it can be a concept including other electrical components such as a battery management system (BMS) up to a battery cell module assembly. Conventional battery modules included a module case made of a metal material to house the battery cells and have mechanical rigidity, and a frame for inserting and fixing the battery cells. Different from the conventional ones, the battery module B included in the battery pack A of this embodiment can have the module case, the frame, etc. omitted or minimized.

[0041] Between the plurality of battery cells C housed in the pack case A1, spaces will exist depending on the form and housing method of the battery cells C. In this embodiment, a resin layer D is included relatively at the lower part in the space between the battery cells C. Desirably, the resin layer D fills relatively the lower part in the space between the battery cells C so that no space exists between the battery cell C and the resin layer D. An inorganic film E is included relatively at the upper part in the space between the battery cells C. Desirably, the inorganic film E fills relatively the upper part in the space between the battery cells C so that no space exists between the battery cell C and the inorganic film E.

[0042] The resin layer D may be formed from the bottom of the pack case A1. The resin layer D can surround the bottom and side surfaces of the battery cell C. In another example, the resin layer D may be formed from the lower end of the battery cell C. The resin layer D can surround the side surface excluding the bottom surface of the battery cell C. The resin layer D supports the battery cell C in place of the module case and the frame of the conventional battery module, and in particular, can serve to mechanically protect the side surface of the battery cell C. Thereby, side ruptures of the battery cell C can be prevented.

[0043] For example, the battery cell C can be a cylindrical battery cell. The battery cell C can be vertically stored in the pack case A1. The resin layer D and the inorganic film E can mechanically support by surrounding the side surface of the battery cell C.

[0044] The inorganic film E may be formed above the resin layer D. The inorganic film E can surround the upper surface and the side surface of the battery cell C. In another example, the inorganic film E can surround only the side surface of the battery cell C. The inorganic film E can be formed to fill up to the upper surface of the pack case A1. The resin layer D can surround the side surface excluding the bottom surface of the battery cell C. The resin layer D can support the battery cell C in place of the module case and the frame of a conventional battery module, and particularly can play a role of mechanically protecting the side surface of the battery cell C. The inorganic film E can have a higher flame retardancy than the resin layer D. The inorganic film E can ensure the flame retardancy of the battery pack A as compared with the case where the inside of the battery pack A is entirely filled with the resin layer.

[0045] The concept of "relative" changes depending on the reference. In this embodiment, the bottom surface of the pack case A1 is used as the reference. That is, "relatively lower" indicates the side closer to the bottom of the pack case A1. Between the plurality of battery cells C, the resin layer D and the inorganic film E are formed in the height direction along the upward direction perpendicular to the bottom surface of the pack case A1. The space between the battery cells C in the height direction can be filled with the resin layer D and the inorganic film E without gaps. There is a discontinuity between the materials filling the space 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 film E is included on the other side.

[0046] After storing a plurality of battery cells C in the pack case A1 first, the resin layer D and the inorganic film E can be formed in the space between the battery cells C. In such a case, as shown in FIG. 1, the resin layer D can be formed on the side closer to the bottom surface of the pack case A1, and the inorganic film E can be formed above the resin layer D in the height direction.

[0047] In another example, after a resin layer D and an inorganic film E are first formed outside the packing case A1 in the space between a plurality of battery cells C, they can be housed in the packing case A1. In this case, the height-direction positions of the resin layer D and the inorganic film E can change along the direction in which the plurality of battery cells C are housed in the packing case A1. For example, when the resin layer D is formed on the bottom side and housed in the packing case A1, as shown in FIG. 1, the resin layer D is located on the side closer to the bottom surface of the packing case A1, and the inorganic film E can be located above the resin layer D in the height direction. Conversely, when the inorganic film E is formed on the bottom side and housed in the packing case A1, the inorganic film E is located on the side closer to the bottom surface of the packing case A1, and the resin layer D can be located above the inorganic film E in the height direction.

[0048] In particular, the resin layer D and the inorganic film E are a double layer formed by forced phase separation while a composition containing a base resin and an inorganic filler is cured. There is an advantage that the step of forming the resin layer D and the step of forming the inorganic film E do not have to be performed separately. Further, since an inorganic filler is included, not only can the weight of the battery pack A be reduced, but also a relatively expensive base resin can be used less, so that it can contribute to cost reduction in manufacturing.

[0049] The forced phase separation of the composition can be used to position the inorganic film E in a portion that requires more flame retardancy in the height direction. For example, when a vent portion is formed at the upper end of the battery cell C, the inorganic film E can be formed to be located at the upper end portion of the battery cell C so as to surround such a vent portion. Conversely, when a vent portion is formed at the lower end of the battery cell C, the inorganic film E can be formed to be located at the lower end portion of the battery cell C so as to surround such a vent portion. By using the forced phase separation of the composition in a state where the lower end of the battery cell C is arranged so as to face upward, the inorganic film E can be formed on the lower end side of the battery cell C. The inorganic film E can more effectively block heat transfer to the surroundings when an abnormal situation occurs in the battery cell C.

[0050] The resin layer D is formed to have a thickness of 1 / 2 or less based on the height of the battery cell C, and the inorganic film E can be formed to have a thickness of 1 / 2 or more. In another example, the resin layer D is formed to have a thickness of 2 / 3 or less based on the height of the battery cell C, and the inorganic film E can be formed to have a thickness of 1 / 3 or more. In yet another example, the resin layer D is formed to have a thickness of 4 / 5 or less based on the height of the battery cell C, and the inorganic film E can be formed to have a thickness of 1 / 5 or more. The greater the thickness of the resin layer D is than that of the inorganic film 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 film E is made smaller than that of the resin layer D, but it is desirable that the thickness be equal to or greater than the minimum thickness at which the effect of flame retardancy can be obtained.

[0051] It is desirable that the base resin have a Shore hardness A of 80 or more and a Shore hardness D of 30 or more after curing. The Shore hardness A is well-known as a means for measuring the hardness of soft rubber, and the Shore hardness D is well-known as a means for measuring the hardness of hard rubber. The Shore hardness A and the Shore hardness D have values between 0 and 100. Those with a Shore hardness A of 80 or more and a Shore hardness D of 30 or more fall within the categories of hard and extra hard in the well-known Shore hardness scale. For example, tires, shoe heels, and cart wheels belong to the hard category, and safety helmets belong to the extra hard category. When using a base resin having a Shore hardness A of 80 or more and a Shore hardness D of 30 or more after curing, the rigidity of the resin layer D can be ensured, and the battery cell C can be mechanically supported sufficiently, enabling the mechanical rigidity of the battery pack A to be ensured without having a module case or a frame.

[0052] Examples of the base resin include epoxy, urethane, etc., and for the purpose of ensuring rigidity, it is desirable that it be epoxy.

[0053] Epoxy, urethane, etc. are not flame-retardant, so further supplementation of flame retardancy is required. When epoxy or urethane is used as a potting agent in the conventional battery pack field, it is sometimes used by adding a phosphorus-based flame retardant or a flame-retardant filler and uniformly dispersing them. However, such phosphorus-based flame retardants and flame-retardant fillers may increase the price and weight.

[0054] The inorganic filler is preferably hollow glass beads. The hollow glass beads have a smaller density than the phosphorus-based flame retardant and the flame-retardant filler, and have flame retardancy. Also, it is advantageous for weight reduction and the price is low.

[0055] In the present invention, instead of curing the base resin with the inorganic filler uniformly dispersed therein, using the forced phase separation of the mixture due to the density difference, the base resin is collected on one side and the inorganic filler is collected on the other side and cured. This is the feature.

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

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

[0058] Figure 2b shows a state in which the inorganic filler F2 having a smaller density gathers relatively at the upper part due to the density difference, and the base resin F1 is mainly located below it.

[0059] The composition F containing the base resin F1 and the inorganic filler F2 undergoes phase separation due to the density difference over time. The inorganic filler F2 with a lower density accumulates relatively in the upper part to form an upper layer, and the base resin F1 accumulates relatively in the lower part to form a lower layer. When cured in this state, a resin layer D is formed from the base resin F1 that has accumulated relatively in the lower part, and an inorganic film E is formed from the inorganic filler F2 that has accumulated relatively in the upper part. The curing can be thermal curing, UV curing, or natural curing depending on the properties of the base resin.

[0060] Thus, after the base resin F1 is completely cured, an inorganic film E mainly containing the inorganic filler F2 is formed relatively in the upper part. A resin layer D mainly containing the base resin F1 is formed relatively in the 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 can be carried out as follows.

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

[0064] In curing the composition F, while curing as described in FIG. 2, by forcibly phase-separating the base resin F1 and the inorganic filler F2 due to the density difference, a resin layer D that fills the relatively lower part in the space between the plurality of battery cells C and an inorganic film E that fills the relatively upper part in the space between the plurality of battery cells C can be formed.

[0065] When cured in a state where the inorganic filler F2 is uniformly dispersed in the base resin F1, it is necessary to increase the content of the inorganic filler F2 to ensure the desired degree of flame retardancy. Since only increasing the content of the inorganic filler F2 requires decreasing the content of the base resin F1, it is not desirable in terms of ensuring rigidity.

[0066] In the present invention, the flame-retardant inorganic filler F2 is collected on one side to form an inorganic film E, and the flame retardancy of the portion where the inorganic film E is located can be particularly ensured. It has the effect of ensuring the desired degree of flame retardancy with a smaller amount of the inorganic filler F2 than in the case of curing in a state where the inorganic filler F2 is uniformly dispersed in the base resin F1.

[0067] In order to manufacture the battery pack A, it is necessary to select the initial viscosity and the initial curing time of the base resin F1 that facilitate phase separation. And the content of the inorganic filler F2 capable of ensuring flame retardancy (this determines the thickness of the inorganic film) must be determined.

[0068] It is desirable that the initial viscosity of the base resin F1 is 1000 cp or less. The initial viscosity is the viscosity before gelation starts. If the initial viscosity is greater than 1000 cp, even when using the low-density inorganic filler F2, it becomes difficult for the inorganic filler F2 to move upward from the base resin F1, making it difficult to cause complete phase separation, and there is a high possibility of curing in a state where the inorganic filler F2 is uniformly dispersed in the base resin F1. If the initial viscosity is too low, the curing time may become long or the hardness of the resin layer D may not be sufficient. The initial viscosity of the base resin F1 is determined in consideration of such points. The initial viscosity of the base resin F1 can be adjusted using the type of the base resin F1, the molecular weight of the base resin F1, additives such as a viscosity modifier, and the like.

[0069] It is desirable that the base resin F1 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 moves upward so that sufficient phase separation occurs. If the initial curing time is too short, phase separation may not occur completely. If the initial curing time is too long, the overall process time becomes long, which is not desirable from the viewpoint of productivity. The initial curing time of the base resin F1 is determined in consideration of such points. The initial curing time of the base resin F1 can be adjusted by the type of the base resin F1, the molecular weight of the base resin F1, or additives such as a curing agent that assists gelation.

[0070] The content of the inorganic filler F2 in the composition F can be 10% or more. Such content indicates the ratio of the volume of the inorganic filler F2 to the total volume of the composition F as a percentage. 10% can 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 since the content of the base resin F1 can be reduced, it is advantageous in terms of price. However, if the content of the inorganic filler F2 is too high, complete phase separation is inhibited, which may be disadvantageous in terms of ensuring mechanical rigidity. The content of the inorganic filler F2 is determined in consideration of such points.

[0071] As described above, by filling the space 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 provided with ribs. Therefore, it is advantageous for weight reduction of the battery pack A, and the space efficiency in the battery pack A does not decrease. That is, even for battery packs of the same size, more battery cells can be incorporated than before to increase the energy density.

[0072] When using the forced phase separation of the composition F in which the inorganic filler F2 is mixed with the base resin F1 capable of forming the resin layer D, the resin layer D and the inorganic film E can be formed in the same process step. The inorganic film E is formed by the forced phase separation of the composition F and enables ensuring flame retardancy. The inorganic film E complements the flame retardancy of the resin layer D.

[0073] As described above, the types of the pack case A1 can be embodied in various ways. Hereinafter, it will be described in detail with examples.

[0074] FIG. 3 is a diagram for explaining 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 film 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 the battery cells included in the battery pack of FIG. 3.

[0078] The battery cell 110 is a secondary battery and may be provided in a cylindrical shape, a pouch shape, or a rectangular shape. Hereinafter, in this embodiment, the description will be limited to the case where the battery cell 110 is a cylindrical battery cell.

[0079] On the upper part of each battery cell 110, a vent part 115 for discharging gas, flame, etc. may be provided. Such a vent part 115 may be formed to have a thickness thinner than the peripheral region at the upper part of the battery cell 110. This is because when an abnormal situation occurs in the battery cell 110 and the internal pressure increases above a certain level, it breaks and discharges the gas and flame to the outside of the battery cell 110 more easily.

[0080] The vent portion 115 may be provided in the form of an opening or notch of a predetermined size. Further, the vent portion 115 can also be formed as a structure in which a film or the like that breaks at a pressure equal to or higher than a certain level is further added to the opening of the predetermined size.

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

[0082] The battery cells 110 can be connected, for example, by wire bonding or the like.

[0083] As shown in FIG. 3, the battery cell assembly 100 is housed in a pack case 300. The resin layer 200 can be filled between the plurality of battery cells 110 of the battery cell assembly 100. Since such a resin layer 200 may be the same as the resin layer D of the above-described embodiment, duplicate description is omitted. The resin layer 200 fills relatively the lower part in the space between the plurality of battery cells 110. The resin layer 200 can secure structural rigidity. In this case, it may not be necessary to use a frame or a module case provided with ribs. Therefore, it is advantageous for weight reduction of the battery pack 10, and the space efficiency in the battery pack 10 does not decrease.

[0084] The inorganic film 250 can also be filled between a plurality of battery cells 110 of the battery cell assembly 100. Since such an inorganic film 250 may be the same as the inorganic film E of the foregoing embodiments, redundant descriptions are omitted. The inorganic film 250 relatively fills the upper part in the space between the plurality of battery cells 110. The inorganic film 250 surrounds the vent part 115. The inorganic film 250 has a thickness formed up to the lower part of the vent part 115 based on the height of the battery cell 110. Since the inorganic film 250 has flame retardancy, it can cope with the flame ejection at the vent part 115.

[0085] The pack case 300 can accommodate the battery cell assembly 100, the resin layer 200, and the inorganic film 250. For this purpose, 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 film 250.

[0086] Specifically, the pack case 300 of the present embodiment includes a bottom frame 305 (or a pack tray) that accommodates the lower end portion of the battery cell 110. And it may further include a cover frame (not shown) that covers the upper end portion of the battery cell 110.

[0087] The bottom frame 305 can support the battery cell assembly 100. For this purpose, the bottom frame 305 may have a predetermined area capable of supporting the battery cell assembly 100. Also, a groove 305a may be formed so that the lower end portion of the battery cell 110 is inserted. By directly placing the battery cell 110 in the bottom frame 305, the frame can be minimized to increase the space efficiency, which is advantageous for improving the energy density. A cell-to-pack (CTP) structure can be implemented.

[0088] Referring to FIG. 3, the adhesive 400 is provided at a predetermined height within the pack case 300 and fills a part of the groove 305a up to a certain height. The adhesive 400 further firmly fixes the battery cell 110 inserted into the groove 305a. The adhesive 400 may at least partially cover the lower end portion of the battery cell assembly 100.

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

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

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

[0092] As in the foregoing embodiments, a composition including a base resin and an inorganic filler is filled into the space between the battery cells 110.

[0093] In curing the composition, by forcibly phase-separating the base resin and the inorganic filler due to a density difference during curing, a resin layer 200 and an inorganic film 250 are formed.

[0094] As described above, the battery pack 10 according to this embodiment implements a flame retardant and mechanical support structure by adhesive bonding using a resin layer 200, an inorganic film 250, an adhesive 400, etc., so that the process can be further simplified. Instead of a structure in which the battery cells 110 are coupled to a frame or a module case by interference fit, it is implemented by an integrated adhesive bonding structure of the battery cells 110, so that the efficiency of the assembly process can be significantly increased, and the possibility of leakage can be significantly reduced compared to an individual battery cell bonding structure.

[0095] Hereinafter, in the battery pack 10 according to such an embodiment, a mechanism for ensuring safety 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. 3.

[0097] Referring to FIG. 5, in the battery pack 10, an abnormal situation such as overheating may occur in any one of the battery cells 110, and gas, flame, etc. may be generated. At this time, gas, flame 405, etc. can quickly escape from the vent portion 115 of the battery cell 110 in which the abnormal situation has occurred.

[0098] Also, in the case of this embodiment, since the inorganic film 250 is filled while surrounding the vent portion 115 of the battery cell 110, such an inorganic film can effectively prevent the propagation of flame 405, etc. to the side of the battery cell 110 adjacent to the battery cell 110 in which the abnormal situation has occurred and the vent portion 115 has been opened. As a result, the possibility of chain ignition is reduced.

[0099] On the other hand, since the inorganic film 250 basically has brittleness, when the flame 405, etc. occurs, the flame 405, etc. can escape more quickly to the outside of the battery pack 10 before being propagated to the side of the adjacent battery cell 110 around the battery cell 110 in which the abnormal situation has occurred.

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

[0101] Furthermore, when an abnormal situation 410 occurs on the side surface of the battery cell 110, the resin layer 200 located on the side surface can suppress side ruptures.

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

[0103] Referring to FIG. 6, the battery pack 20 may include a battery cell assembly 100, a resin layer 200, an inorganic film 250, a pack case 310, and an adhesive 420. Since the battery pack 20 according to this embodiment is similar to the battery pack 10 of the foregoing embodiment, duplicate descriptions of substantially the same or similar configurations as those of the foregoing embodiment will be omitted, and the description will be centered on the differences from the foregoing embodiment.

[0104] FIG. 7 is a diagram for explaining the battery cell assembly of the battery pack of FIG. 6.

[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 case and the second case are included, they can be provided with a plastic material. When the first case and the second case are included, they can be coupled to the pack case 310. For example, they can be coupled by an adhesive bond or the like for simplifying the assembly process.

[0108] The bus bar assembly 150 can be electrically connected to the battery cell 110. Such a bus bar assembly 150 can be connected to the battery cell 110 by laser welding or wire bonding or the like. The bus bar assembly 150 can be electrically connected to the battery cell 110 above or below the battery cell assembly 100. In this embodiment, an example of connecting below the battery cell assembly 100 is given.

[0109] The pack case 310 can accommodate the battery cell assembly 100, the resin layer 200, and the inorganic film 250. For this purpose, the pack case 310 can be provided with an accommodation space capable of accommodating the battery cell assembly 100, the resin layer 200, and the inorganic film 250.

[0110] FIG. 8 is a diagram for explaining the pack case of FIG. 6.

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

[0112] The base case 320 can support the battery cell assembly 100. For this purpose, the base case 320 can have a predetermined area for supporting the battery cell assembly 100.

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

[0114] The cross beam 330 can absorb or buffer an external impact applied from outside the pack case 310, and prevent the transmission of the impact to the battery cell 110 side inside the pack case 310.

[0115] Referring further to FIG. 6, the adhesive 420 is provided at a predetermined height within the pack case 310 and can at least partially cover the lower end portion of the battery cell assembly 100.

[0116] Specifically, the adhesive 420 can be provided to fill the inner surface of the base case 320 at a predetermined height. The lower portion of the battery cell 110 of the battery cell assembly 100 and the bus bar assembly 150 can be immersed in such an adhesive 420.

[0117] In the case of this embodiment, the battery cell assembly 100 can be fixed within the pack case 310 by the adhesive 420. When a waterproof adhesive is used as the adhesive 420, the waterproofing process can be made simpler, the manufacturing cost can be reduced, and the waterproof reliability can be improved.

[0118] Hereinafter, the manufacturing method of such a battery pack 20 will be described more specifically.

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

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

[0121] As described in the foregoing embodiments, a composition containing a base resin and an inorganic filler is filled into the space between battery cells 110, and while curing, the base resin and the inorganic filler are forcibly phase-separated due to the density difference to form a resin layer 200 and an inorganic film 250.

[0122] Thus, the battery pack 20 according to this embodiment realizes a waterproof, flame-retardant, and mechanical support structure by adhesive bonding using a resin layer 200, an inorganic film 250, an adhesive 420, etc., so that the process can be further simplified.

[0123] FIG. 9 is a diagram for explaining an automobile according to an embodiment of the present invention.

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

[0125] According to various embodiments as described above, it is possible to provide battery packs A, 10, 20 with reduced possibility of thermal runaway and reduced reduction in space efficiency, and an automobile 1 including the same.

[0126] Hereinafter, the present invention will be described in more detail with reference to experimental examples.

[0127] The presence or absence of phase separation and the flame retardancy due to the viscosity of the base resin were confirmed. Experiments were conducted using a base resin having an initial curing time of 30 minutes or more during which sufficient phase separation could occur.

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

[0129] Comparative Example 1 and Comparative Example 2 were based on an epoxy resin with an initial viscosity of 2000 cp.

[0130] Comparative Example 1 was obtained by curing only the base resin without a low-density filler. It becomes a sample consisting only of a resin layer as shown in Fig. 10a. Referring to Fig. 10b, it can be confirmed that such a sample has a persistent flame without extinguishing during the flame retardancy test. It is difficult to expect flame retardancy from only the base resin.

[0131] Comparative Example 2 was obtained by mixing 10% of hollow glass beads into the base resin and curing it. Referring to Fig. 11a, it was confirmed that phase separation did not occur from the outer surface or cross-section of the sample. As shown in Fig. 11b, such a sample had a persistent flame without extinguishing during the flame retardancy test. Therefore, it can be seen that appropriate flame retardancy cannot be ensured even when hollow glass beads are included if phase separation does not occur. The reason for the lack of phase separation was the high initial viscosity of the base resin.

[0132] Fig. 12a is a photograph of the cured state of the example, and Fig. 12b is a photograph of the flame retardancy test of the example.

[0133] The example was obtained by using an epoxy resin with an initial viscosity of 1000 cp as the base resin, mixing 10% of hollow glass beads, and curing it. Referring to Fig. 12a, it was confirmed that complete phase separation occurred from the outer surface and cross-section of the sample. The layer F2' of hollow glass beads that was phase-separated and aggregated in the upper layer can be confirmed. Also, since the layer F2' of hollow glass beads has continuity in the vertical and horizontal directions of the sample, a thing that can be called an inorganic coating can be confirmed. As a result of heating the phase-separated part, that is, the layer F2' of hollow glass beads with a torch, as shown in Fig. 12b, the fire went out within 10 seconds after the heating ended. It can be seen that sufficient flame retardancy is ensured.

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

[0135] As described above, the present invention has been described with reference to the limited examples and drawings. However, the present invention is not limited thereto, and various modifications and variations can be made within the equivalent scope of the technical idea and claims of the present invention by those having ordinary knowledge in the technical field to which the present invention pertains.

Explanation of Reference Numerals

[0136] A, 10, 20 Battery Pack A1, 300, 310 Pack Case B Battery Module C Battery Cell D, 200 Resin Layer E, 250 Inorganic Film F Composition F1 Base Resin F2 Inorganic Filler F2’ Layer of Hollow Glass Beads 1 Automobile 100 Battery Cell Assembly 115 Vent Part 150 Busbar Assembly 305 Bottom Frame 320 Base Case 330 Cross Beam 400, 420 Adhesive

Claims

1. A battery pack, comprising: a pack case; a battery cell assembly including a plurality of battery cells housed in the pack case; a resin layer filling relatively the lower part in the space between the plurality of battery cells; an inorganic film filling relatively the upper part in the space between the plurality of battery cells.

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

3. The battery pack according to Claim 1, wherein the battery cell is a cylindrical battery cell, the battery cell is vertically housed in the pack case, and the resin layer and the inorganic film surround the side surface of the battery cell.

4. The battery pack according to Claim 1, wherein the resin layer and the inorganic film are a double layer formed by forcibly phase-separating a composition containing a base resin and an inorganic filler while the composition is cured.

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 hollow glass beads.

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

8. The battery pack according to Claim 4, wherein a 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 curing.

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 an 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 an upper part or a lower part, and the inorganic film surrounds the vent portion.

13. The battery pack according to Claim 1, wherein the pack case includes a bottom frame or a pack tray for housing a lower end portion of the battery cell.

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

15. The pack case is a base case that supports the battery cell assembly, and cross beams provided on both sides of the base case and coupled to the upper end portion of the battery cell assembly. The battery pack according to claim 1, characterized by comprising the above.

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

17. Storing a plurality of battery cells in a pack case; Filling a space between the plurality of battery cells with a composition containing a base resin and an inorganic filler; In curing the composition, by forcibly phase-separating the base resin and the inorganic filler due to a density difference during curing, a resin layer that relatively fills the lower part in the space between the plurality of battery cells and an inorganic film that relatively fills the upper part in the space between the plurality of battery cells are formed. A method for manufacturing a battery pack, including the above.

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

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

20. The method for manufacturing a battery pack according to claim 17, wherein in the composition, a content of the inorganic filler 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 curing.

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. An automobile, characterized by including at least one battery pack according to any one of claims 1 to 16.

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