Battery pack

Abstract

In one example, the disclosed battery pack includes a pack case having a base plate and a plurality of cell units mounted on the base plate, and a thermal resin and a TIM pad are interposed in parallel between the bottom surface of the cell unit and the base plate to fix the cell unit, and the adhesive strength of the TIM pad is weaker than the adhesive strength of the thermal resin.

Description

[Technical Field]

[0001] The present invention relates to a battery pack, and more particularly to a battery pack that can extend its lifespan with minimal maintenance by enabling replacement of a battery cell when a problem occurs in the battery cell, without the need to discard the entire battery pack.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0072978, filed June 7, 2023, and all contents disclosed in the documents of said Korean patent application are incorporated herein by reference. [Background technology]

[0003] To improve the space utilization rate of a battery pack, a battery pack with a cell-to-pack structure has been proposed. The cell-to-pack structure has the advantage of improving the space utilization rate of the battery pack by directly assembling multiple battery cells into a battery pack without the need for a modular structure.

[0004] In the cell-to-pack structure, a new structure has been proposed to efficiently mount a large number of battery cells in a pack case by eliminating or simplifying a separate module housing. For example, a side frame can be attached to a cell unit (corresponding to a conventional battery module) in which multiple battery cells form a group, and the side frames of adjacent cell units can be combined to provide sufficient rigidity, allowing the structure to replace the role of a conventional pack cross beam (a cross beam integrated into the pack case).

[0005] In addition, by omitting a separate module housing, thermal resin is placed between the bottom of the cell unit, where the battery cells are exposed, and the base plate of the pack case, which promotes conductive heat dissipation from the cell unit and also fixes the cell unit more firmly as the thermal resin hardens.

[0006] However, a battery pack structure that further fixes the cell unit by curing the thermal resin has many advantages over a cell-to-pack structure, such as improving the space utilization of the battery pack by directly assembling multiple battery cells into a battery pack without the need for a modular structure, and improving heat dissipation performance through thermal conduction compared to a structure with a single interposed module housing. However, it also has disadvantages in terms of battery pack maintenance. That is, such a cell-to-pack structure makes it very difficult to disassemble an assembled battery pack into individual cell units. For example, a structure that fixes the bottom of the cell unit by curing the thermal resin can cause damage to the battery cells bonded to the thermal resin when the cell unit is removed, which can lead to dangerous consequences such as electrolyte leakage.

[0007] There is a strong need for the development of a battery pack with a cell-to-pack structure that allows a battery pack to be easily disassembled into cell units, and therefore allows maintenance of the battery pack by replacing the cell unit even if a problem occurs in only one battery cell in the battery pack, thereby enabling expensive battery packs to be used to the end of their designed lifespan without being discarded. Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a battery pack having a cell-to-pack structure in which any cell unit can be easily removed regardless of the assembly order, thereby facilitating the replacement of a defective battery cell.

[0009] However, the technical problems that the present invention aims to solve are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Means for solving the problem]

[0010] The present invention relates to a battery pack, which in one example includes a pack case having a base plate and a plurality of cell units mounted on the base plate, wherein a thermal resin and a TIM pad are interposed in parallel between the bottom surface of the cell unit and the base plate to fix the cell unit, and the adhesive strength of the TIM pad is weaker than the adhesive strength of the thermal resin.

[0011] The thermal resin can be applied along the periphery of the TIM pad.

[0012] The adhesive strength of the cell unit to the base plate is adjusted as the area ratio between the adhesive area of ​​the thermal resin and the adhesive area of ​​the TIM pad.

[0013] The thermal resin may form a curable adhesive layer, and the TIM pad may form a non-curable adhesive layer.

[0014] In an exemplary embodiment, the bonding area of ​​the TIM pad may occupy 60 to 90% of the entire bottom surface area of ​​the cell unit.

[0015] The TIM pads may be in the form of a pair and may be spaced apart from each other and disposed on the bottom surface of the cell unit.

[0016] In this case, the thermal resin applied along the periphery of each of the pair of TIM pads can be insulated from each other.

[0017] Meanwhile, in the battery pack of the present invention, the pack case includes a cross beam connected to the base plate so as to horizontally divide the storage space inside the base plate, and the cell unit has a side frame fixed to the cross beam, and the side frames of adjacent cell units along the vertical direction share the upper surface of the cross beam located between the side frames of the adjacent cell units and may not overlap each other vertically.

[0018] The side frame includes a side plate that surrounds the side of the cell unit and a support block that protrudes from the side plate, and the support blocks of adjacent cell units along the vertical direction can occupy areas on the upper surface of the cross beam that do not overlap each other.

[0019] For example, the side frame may include a plurality of support blocks spaced apart from one another, and the support blocks of adjacent cell units along the longitudinal direction may be arranged alternately with respect to the upper surface of the cross beam.

[0020] The cell units can then be fixed to the cross beams by bolts that pass vertically through the support blocks. [Effects of the Invention]

[0021] In the battery pack of the present invention having the above-described configuration, the adhesive force for fixing the cell unit to the base plate is provided by both the thermal resin and the TIM pad. However, by limiting the adhesive area so that the curable thermal resin is only locally attached to the bottom surface of the cell unit, it becomes easy to separate a cell unit that has developed a problem from the battery pack, and this makes it possible to reuse the entire battery pack through maintenance without having to discard it.

[0022] In particular, the battery pack of the present invention is applicable to a cell-to-pack structure, and while heat dissipation from the bottom surface of the cell unit is sufficiently increased by both the thermal resin and the TIM pad, the adhesive area of ​​the non-curable TIM pad, which has relatively low adhesive strength, can be adjusted to easily design the fixing strength to a level that is firm but allows for subsequent separation of the cell unit.

[0023] Furthermore, the side frames of each cell unit share the top surface of one cross beam but are designed so that they do not overlap each other vertically. This means that even if a problem occurs with only one cell unit in an assembled battery pack, the problematic cell unit can be easily removed regardless of the assembly order.

[0024] However, the technical effects that can be obtained by the present invention are not limited to the effects described above, and other effects not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0025] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical concept of the present invention, and therefore the present invention should not be interpreted as being limited solely to the matters depicted in such drawings. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a view showing a fixing structure of a cell unit in a battery pack according to the present invention; [Figure 2] FIG. 2 is a cross-sectional view taken along line "AA" in FIG. [Figure 3] 3 is a diagram illustrating an example of a state in which the cell unit of FIG. 2 is separated from the battery pack. [Figure 4] 1 is a diagram illustrating an example of an installation structure of a thermal resin and a TIM pad. [Figure 5] 1 is a view showing a cell unit mounting structure according to an embodiment of the present invention; [Figure 6] FIG. 6 is a plan view of the battery pack according to the embodiment of FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0027] Because the present invention can be modified in various ways and can have various embodiments, specific embodiments will be described in detail below.

[0028] However, this is not intended to limit the invention to any particular embodiment, but rather to be understood as including all modifications, equivalents, or alternatives falling within the spirit and scope of the invention.

[0029] In the present invention, terms such as "comprise" and "have" are intended to specify the presence of features, numbers, steps, operations, components, parts or combinations thereof described in the specification, and may be understood as not precluding the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0030] Furthermore, in the present invention, when a layer, film, region, plate, or other portion is described as being "on" another portion, this includes not only the case where it is "directly on" the other portion, but also the case where there is another portion therebetween. Conversely, when a layer, film, region, plate, or other portion is described as being "under" the other portion, this includes not only the case where it is "directly under" the other portion, but also the case where there is another portion therebetween. Furthermore, in this application, being "located on" can include not only the case where it is located at the top, but also the case where it is located at the bottom.

[0031] The present invention relates to a battery pack, which in one example includes a pack case having a base plate and a plurality of cell units mounted on the base plate, wherein a thermal resin and a TIM pad are interposed in parallel between the bottom surface of the cell unit and the base plate to fix the cell unit, and the adhesive strength of the TIM pad is weaker than the adhesive strength of the thermal resin.

[0032] In the battery pack of the present invention having such a configuration, the adhesive force for fixing the cell unit to the base plate is provided by both the thermal resin and the TIM pad, but by limiting the adhesive area so that the curable thermal resin is only locally fixed to the bottom surface of the cell unit, it becomes easy to separate a cell unit that has developed a problem from the battery pack, and this makes it possible to reuse the entire battery pack through maintenance without having to discard it.

[0033] Hereinafter, specific embodiments of the battery pack 10 according to the present invention will be described in detail with reference to the accompanying drawings. For reference, the directions of front, back, up, down, left, and right used in the following description to designate relative positions are intended to facilitate understanding of the invention, and unless otherwise specified, are based on the directions shown in the drawings.

[0034] (First embodiment) FIG. 1 is a view showing a fixing structure of a cell unit 200 in a battery pack 10 according to the present invention, and FIG. 2 is a cross-sectional view taken along line "AA" in FIG.

[0035] The present invention relates to a battery pack 10, which includes a pack case 100 and a plurality of cell units 200 mounted in the pack case 100. Here, the cell unit 200 refers to a unit in which a plurality of battery cells 210 are bundled together as a group, and includes a structure for unitizing the plurality of battery cells 210. For example, the cell unit 200 may include a bus bar frame assembly 220 that mechanically and electrically couples the plurality of battery cells 210 to both lateral ends from which the leads (not shown) of the battery cells 210 protrude, and side frames 230 that protect the battery cells 210 on both longitudinal ends. The illustrated cell unit 200 has the battery cells 210 exposed at its bottom without any additional structure, so that it is compatible with a battery pack 10 having a cell-to-pack structure.

[0036] The pack case 100 includes a base plate 110, which is a bottom plate. The base plate 110 supports the bottom surfaces of the cell units 200 and absorbs heat from the bottom surfaces of the cell units 200 in the form of thermal conduction and dissipates the heat to the outside. To dissipate the absorbed heat to the outside using a refrigerant, a heat sink may be built into the base plate 110 itself, or a separate heat sink may be attached to the bottom surface of the base plate 110. Since the configuration of the heat sink itself is not important in this specification, a description and illustration thereof will be omitted.

[0037] The multiple cell units 200 mounted on the base plate 110 are one of the fixing structures for the pack case 100, and a thermal resin 300 with excellent thermal conductivity may be applied to the bottom surface of the cell units 200. The thermal resin 300 has the properties of a viscous gel when first applied, but hardens into a hard solid form after a certain period of time when exposed to air. As a result of the hardening of the thermal resin 300, the bottom surface of the cell units 200 is firmly fixed to the base plate 110.

[0038] However, although the hardening of the thermal resin 300 can firmly secure the cell unit 200, if an abnormality occurs in the cell unit 200, it can prevent it from being separated from the battery pack 10. In most cases, it is almost impossible to separate a cell unit 200 that is fixed with the thermal resin 300, or even if it is removed, it can cause damage to the cell unit itself, other surrounding cell units 200, and the pack case 100. For this reason, battery packs 10 that cannot be repaired must be discarded as a whole.

[0039] The battery pack 10 of the present invention is designed to solve these problems, and is characterized in that the thermal resin 300 and the TIM pad 400 are interposed in parallel between the bottom surface of the cell unit 200 and the base plate 110 to fix the cell unit 200, and the adhesive strength of the TIM pad 400 is weaker than the adhesive strength of the thermal resin 300.

[0040] The thermal resin 300 and the TIM pad 400 are interposed in parallel, meaning that the thermal resin 300 and the TIM pad 400 are not stacked one above the other (interposed in series), but rather that the adhesive surface between the bottom surface of the cell unit 200 and the top surface of the base plate 110 is partly made of the thermal resin 300 and partly made of the TIM pad 400. This can be clearly understood by referring to Figures 1 and 2.

[0041] The TIM pad 400 refers to a slightly elastic pad coated with or incorporating a thermally conductive thermal interface material (TIM). It typically has adhesive layers formed on both sides (e.g., double-sided adhesive tape attached to both sides of the pad). Its function is similar to that of the thermal resin 300, with high thermal conductivity and rapid heat conduction. The adhesive layers on both sides of the TIM pad 400 are respectively attached to the bottom surface of the cell unit 200 and the top surface of the base plate 110, and the bond between the two is much weaker than that of the thermal resin 300. Therefore, the TIM pad 400 alone is insufficient to secure the cell unit 200 to the base plate 110.

[0042] The present invention improves the ease of separation during maintenance while ensuring sufficient fixing strength for the cell unit 200 by combining the properties of the thermal resin 300 and the TIM pad 400, i.e., adhesive strength and curability. That is, the thermal resin 300 forms a curable adhesive layer 310, and the TIM pad 400 forms a non-curable adhesive layer 410. The adhesive strength of the cell unit 200 to the base plate 110 is adjusted by adjusting the area ratio between the adhesive area of ​​the thermal resin 300 and the adhesive area of ​​the TIM pad 400. For example, the adhesive area of ​​the TIM pad 400 can be designed to occupy 60 to 90% of the entire bottom surface area of ​​the cell unit 200, taking into account the adhesive strengths of the thermal resin 300 and the TIM pad 400, so that the cell unit 200 can be separated without applying excessive force.

[0043] 3 is a diagram illustrating an example of a state in which the cell unit 200 of FIG. 2 is separated from the battery pack 10. As shown in FIG. 2, the cell unit 200 is fixed to the base plate 110 by the curable adhesive layer 310 of the thermal resin 300 and the non-curable adhesive layer 410 of the TIM pad 400. When an upward pulling force is applied to the cell unit 200, even a small force overcomes the adhesive force of the non-curable adhesive layer 410 of the TIM pad 400, and the cell unit 200 can be separated without significant damage. For reference, although the curable adhesive layer 310 of the thermal resin 300 is shown remaining on the cell unit 200 in FIG. 3, this is merely an example and does not mean that the cell unit 200 can be separated only in the form shown in FIG. 3.

[0044] 4 is a diagram showing an example of an installation structure of a thermal resin 300 and a TIM pad 400. As shown in Fig. 4(a), one TIM pad 400 may be disposed in the center, and the thermal resin 300 may be applied along the edge of the TIM pad 400. Alternatively, as shown in Fig. 4(b), a pair of TIM pads 400 may be disposed at a distance from each other, and the thermal resin 300 may be applied along each periphery of each TIM pad 400.

[0045] 4(b), the thermal resin 300 applied along each periphery of a pair of TIM pads 400 can be insulated from each other. This creates a blank space with no adhesive layer in the central area of ​​the bottom surface of the cell unit 200. This blank space can act as a separation initiation point that promotes peeling of the curable adhesive layer 310 formed by the thermal resin 300 when the cell unit 200 is separated. This allows the cell unit 200 to be separated more stably.

[0046] (Second embodiment) The adhesive strength of the cell unit 200 to the base plate 110 can be adjusted as the area ratio between the adhesive area of ​​the thermal resin 300 and the adhesive area of ​​the TIM pad 400. However, in some cases, it may be necessary to fix the cell unit 200 more firmly. For example, this may be the case when the battery pack 10 is used in an environment where vibrations occur frequently. For this purpose, a detachable fixing structure may be added to the cell unit 200.

[0047] FIG. 5 is a view showing a mounting structure of a cell unit 200 according to an embodiment of the present invention, and FIG. 6 is a plan view of the battery pack 10 according to the embodiment of FIG.

[0048] 5 and 6, pack case 100 includes a base plate 110, side plates 120 that are joined around the periphery of base plate 110 to form an internal storage space, and cross beams 130 that are joined to base plate 110 to horizontally divide the storage space inside base plate 110. In some embodiments, as shown in FIGS. 5 and 6, the pack case may further include a center beam 140 that vertically divides the storage space inside base plate 110, whereby the storage space of the pack case can be divided into a grid pattern by cross beams 130 and center beam 140.

[0049] One cell unit 200 is mounted in each of the storage spaces partitioned by the cross beam 130, and thus the battery pack 10 accommodates a plurality of cell units 200 to fulfill its design capacity. The cell unit 200 includes a plurality of battery cells 210 and a bus bar frame assembly 220 that mechanically and electrically couples the plurality of battery cells 210 to both lateral ends from which the leads (not shown) of the battery cells 210 protrude. The cell unit 200 also includes side frames 230 on both longitudinal sides that protect the battery cells 210.

[0050] The side frames 230 of adjacent cell units 200 along the vertical direction share the upper surface of the cross beam 130 located between the side frames 230 of the adjacent cell units 200, and do not overlap each other vertically. For example, in the illustrated embodiment, the side frame 230 includes a side plate 232 that surrounds the side of the cell unit 200, and a support block 234 that protrudes relative to the side plate 232. Furthermore, the support blocks 234 of adjacent cell units 200 along the vertical direction occupy areas on the upper surface of the cross beam 130 that do not overlap each other.

[0051] To explain the support block 234 of the cell unit 200 in more detail, the support block 234 of the side frame 230 is a protruding member that can additionally support and secure the cell unit 200 to the cross beam 130, and the cell unit 200 is supported by being seated on the upper surface of the cross beam 130. In addition, the cell unit 200 is secured to the cross beam 130 by a bolt 240 that passes vertically through the support block 234. The head of the bolt 240, which has a larger diameter, is supported at the entrance of the through hole 236, and the fastening force of the bolt 240 acts on the cell unit 200.

[0052] 6 shows a structure in which all cell units 200 are mounted in a battery pack 10. Cell units 200 adjacent in the vertical direction with a cross beam 130 between them are supported and fixed by sharing the cross beam 130 between them. For this reason, the support blocks 234 of cell units 200 adjacent in the vertical direction are alternately arranged on the top surface of the cross beam 130, thereby occupying areas that do not overlap each other.

[0053] 6, the side frames 230, particularly the support blocks 234, of the cell units 200 with the cross beams 130 therebetween share the upper surface of one cross beam 130, but do not overlap one another vertically. This allows for easy upward removal of the problematic cell unit 200, regardless of the assembly order, even if a problem occurs with one of the cell units 200 in the battery pack 10.

[0054] In this way, the battery pack 10 of the present invention allows maintenance of the battery pack 10 by replacing a defective cell unit 200, thereby enabling the expensive battery pack 10 to be fully utilized until its designed lifespan without being discarded altogether.

[0055] The present invention has been described in more detail above through the drawings and embodiments, etc. However, the configurations described in the drawings or embodiments in this specification are merely one embodiment of the present invention and do not represent all of the technical ideas of the present invention, and therefore, there may be various equivalents and modifications that can replace them at the time of filing this application. [Explanation of symbols]

[0056] 10: Battery pack 100: Pack case 110: Base plate 120: Side plate 130: Cross beam 140: Center beam 200: Cell unit 210: Battery cell 220: Busbar frame assembly 230: Side frame 232: Side plate 234: Support block 236:Through hole 240: Bolt 300: Thermal resin 310: Curable adhesive layer 400: TIM pad 410: Non-hardening adhesive layer

Claims

1. a pack case having a base plate; and a plurality of cell units mounted on the base plate; a thermal resin and a TIM pad are interposed in parallel between the bottom surface of the cell unit and the base plate to fix the cell unit; The battery pack has a lower adhesive strength of the TIM pad than the adhesive strength of the thermal resin.

2. The battery pack of claim 1 , wherein the thermal resin is applied along a periphery of the TIM pad.

3. The adhesive strength of the cell unit to the base plate is The battery pack according to claim 1 or 2, wherein the area ratio between the adhesive area of ​​the thermal resin and the adhesive area of ​​the TIM pad is adjusted.

4. The thermal resin forms a curable adhesive layer; 4. The battery pack of claim 3, wherein the TIM pad forms a non-curing adhesive layer.

5. The adhesive area of ​​the TIM pad is: The battery pack according to claim 3 , wherein the cell unit occupies 60 to 90% of the entire bottom surface area.

6. The TIM pad is The battery pack according to claim 2 , comprising a pair of the battery packs spaced apart from each other and disposed on the bottom surface of the cell unit.

7. 7. The battery pack of claim 6, wherein the thermal resin applied along each periphery of the pair of TIM pads is insulated from each other.

8. the pack case includes a cross beam coupled to the base plate so as to laterally define an accommodation space inside the base plate, The cell unit includes a side frame fixed to the cross beam, 3. The battery pack according to claim 1, wherein the side frames of adjacent cell units along the longitudinal direction share an upper surface of the cross beam located between the side frames of the adjacent cell units and do not overlap each other vertically.

9. The side frame is a side plate surrounding a side surface of the cell unit; and a support block protruding from the side plate, The battery pack according to claim 8 , wherein the support blocks of vertically adjacent cell units occupy areas on the top surface of the cross beam that do not overlap each other.

10. The side frame includes a plurality of support blocks spaced apart from one another, The battery pack according to claim 9 , wherein the support blocks of the cell units adjacent along the longitudinal direction are arranged alternately with respect to the upper surface of the cross beam.

11. The cell unit comprises:

10. The battery pack of claim 9, wherein the support block is secured to the cross beam by a bolt that passes vertically through the support block.

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