Battery modules, battery packs and energy storage systems

Abstract

A battery module according to an embodiment of the present invention includes a battery cell stack in which a plurality of battery cells are stacked, a bus bar frame formed on one or both sides of the battery cell stack, and a bus bar on an outer surface of the bus bar frame, the bus bar being electrically connected to an electrode lead of the battery cell stack, the bus bar including a bus bar body connected to the electrode lead, and a heat-resistant member interposed between the bus bar and the bus bar frame.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0060976, filed May 11, 2023, and all contents disclosed in the documents of said Korean patent application are incorporated herein by reference. [Background technology]

[0002] In modern society, the use of portable devices such as mobile phones, laptops, video cameras, digital cameras, and energy storage systems (ESS) has become commonplace, leading to active development of related technologies. Furthermore, rechargeable secondary batteries are a solution to address air pollution caused by existing gasoline-powered vehicles that use fossil fuels, and are used as the power source for electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (P-HEVs), creating a growing need for development of secondary batteries.

[0003] Currently commercially available secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries. Of these, lithium secondary batteries are attracting the most attention due to their advantages of being freely chargeable and dischargeable, having a low self-discharge rate, and having a high energy density.

[0004] FIG. 1 shows a front view of a battery module equipped with a busbar 30 according to the prior art. FIG. 2 shows a cross-sectional view taken along line AA in FIG. 1. FIG. 1 also shows a front view of a battery module or battery pack after electrode leads 11 have been welded to the busbar 30. The battery module includes a battery cell stack in which a plurality of battery cells 10 are stacked, electrode leads 11 protruding from one or both ends of the battery cells 10, a busbar frame 20, a busbar 30, and end plates 40 at both ends of the battery cell stack. The electrode leads 11 pass through slits 21 in the busbar frame 20 and are welded to the busbar 30 on the outer surface of the busbar frame 20. The electrode leads 11 can be electrically connected to the busbar 30. The busbar 30 is made of a metal material, such as copper, aluminum, or a mixture thereof.

[0005] According to the prior art of Figure 1, a busbar frame 20 includes hook-shaped fixing portions 22 at its upper and lower ends, respectively, and the busbar 30 can be fixed to the outer surface of the busbar frame 20 by the hook-shaped fixing portions 22. The cross-sectional view of Figure 2 also shows that the busbar 30 is hook-coupled to the hook-shaped fixing portions 22. The upper fixing portion 22 has a snap fit structure, and the lower fixing portion 22 has a guide rib structure.

[0006] The bus bar frame 20 further includes bus bar support portions 23, which support the bus bars 30. As a result, the bus bar support portions 23 support the bus bars 30 when the bus bars 30 are welded or when an actual battery module or battery pack is used.

[0007] Meanwhile, reducing the thickness of the busbars can reduce the cost of materials required for manufacturing the busbars and increase the energy density of the battery module and / or battery pack. However, heat generated in the busbars during charging and discharging of the battery cells is transferred to the busbar frame due to the reduced thickness of the busbars, which can cause thermal deformation of the injection-molded busbar frame. For example, the fixing portion 22 and / or the busbar support portion 23 of the busbar frame 20 shown in FIG. 2 may be thermally deformed, and in some cases, the entire body of the busbar frame 20 may be thermally deformed.

[0008] Therefore, a solution is needed that can prevent deformation of the bus bar frame by blocking heat transfer from the bus bar to the bus bar frame while reducing the thickness of the bus bar. Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a battery module, a battery pack, and an energy storage system that can prevent deformation of a bus bar frame due to a temperature rise of the bus bar while reducing the thickness of the bus bar.

[0010] However, the problems to be solved by the embodiments of the present invention are not limited to the above problems, and can be variously expanded within the scope of the technical ideas included in the present invention. [Means for solving the problem]

[0011] A battery module according to an embodiment of the present invention includes a battery cell stack in which a plurality of battery cells are stacked, a bus bar frame formed on one or both sides of the battery cell stack, and a bus bar electrically connected to an electrode lead of the battery cell stack on an outer surface of the bus bar frame, wherein the bus bar may include a bus bar body connected to the electrode lead and a heat-resistant member interposed between the bus bar and the bus bar frame.

[0012] The heat-resistant member may include a heat-sealing portion for heat-sealing the heat-resistant member to the bus bar frame.

[0013] At least one of the corners of the busbar body may include a recess, and the heat-resistant member may be exposed in the recess, where the heat-sealing portion is provided.

[0014] When viewed from the front, the busbar body and the heat-resistant member may have the same shape, and the busbar body may further include the recess.

[0015] The exposed heat-resistant member may have holes formed therein, and the heat-resistant member may be joined to the bus bar frame through the holes.

[0016] The heat-sealed portion may be spaced a predetermined distance from the periphery of the recess of the busbar body.

[0017] The heat-sealing portion and the recessed portion of the bus bar body may be provided at two corners of the bus bar that face each other diagonally.

[0018] The heat-sealing portion may be made of the same material as the bus bar frame.

[0019] The busbar body may be made of a metal material, and the heat-resistant member may be made of a material having a glass-transition temperature (Tg) higher than the maximum temperature rise of the battery cells of the busbar body during charging and discharging.

[0020] The heat resistant member can include a polymer having a middle or high glass transition temperature (Tg).

[0021] The busbar body and the heat-resistant member may be bonded to each other with an adhesive.

[0022] The adhesive may be a heat-resistant epoxy adhesive.

[0023] The thickness of the busbar body may be 20% to 80% of the overall thickness of the busbar.

[0024] The bus bar may include a slit through which the electrode lead passes, and the slit may be integrally formed at the same position on the bus bar body and the heat-resistant member.

[0025] According to another embodiment of the present invention, a battery pack including the battery module according to the above embodiment can be provided.

[0026] According to another embodiment of the present invention, there is provided an energy storage system including the battery pack according to the above embodiment. [Effects of the Invention]

[0027] According to the present invention, by reducing the thickness of the busbar, it is possible to reduce the cost of materials required for manufacturing the busbar and increase the energy density of the battery module and / or battery pack. Furthermore, even though the thickness of the busbar is reduced, it is possible to prevent deformation of the busbar frame due to an increase in temperature of the busbar.

[0028] The effects of the present invention are not limited to those mentioned above, and other effects not mentioned above will be clearly understood by those skilled in the art from the description of the claims. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a front view of a battery module equipped with bus bars according to the prior art. [Figure 2] 2 shows a cross-sectional view taken along line AA in FIG. 1. [Figure 3] 1 is a front view showing a battery module according to an embodiment of the present invention; [Figure 4] 4 is a perspective view of a bus bar, which is one component of the battery module of FIG. 3 and can be attached to the battery module. FIG. [Figure 5] FIG. 5 is an exploded perspective view of the bus bar of FIG. 4. [Figure 6] 4 is an enlarged view of a portion of FIG. 3 showing the bus bar of FIG. 3 installed; [Figure 7] A comparison table of the properties of High Tg FR-4 and FR-4 is shown below. DETAILED DESCRIPTION OF THE INVENTION

[0030] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention may be embodied in various different forms and is not limited to the embodiments set forth herein.

[0031] In order to clearly explain the present invention, parts unnecessary for the explanation are omitted, and the same reference numerals are used throughout the specification to refer to the same or similar components.

[0032] Furthermore, the size and thickness of each component shown in the drawings are arbitrarily shown for the convenience of explanation, and the present invention is not necessarily limited to those shown in the drawings. In the drawings, thicknesses are exaggerated to clearly show multiple layers and regions. In the drawings, thicknesses of some layers and regions are exaggerated for the convenience of explanation.

[0033] Furthermore, when a layer, film, region, plate, or other part is said to be "above" another part, this does not only mean that it is "directly above" that part, but also includes cases where there are other parts in between. Conversely, when a part is said to be "directly above" another part, it means that there are no other parts in between. Furthermore, being "above" a reference part means being located above or below the reference part, and does not necessarily mean being "above" in the direction opposite to gravity.

[0034] Furthermore, throughout the specification, when a part is said to "comprise" a certain element, this does not mean that it excludes other elements and may further include other elements, unless specifically stated to the contrary.

[0035] Also, throughout the specification, "on a plane" means when the subject part is viewed from above, and "on a cross section" means when the subject part is cut vertically and viewed from the side.

[0036] Hereinafter, a battery module according to an embodiment of the present invention will be described with reference to FIGS.

[0037] Fig. 3 is a front view of a battery module according to one embodiment of the present invention. Fig. 4 is a perspective view of a bus bar, which is one component of the battery module of Fig. 3 and can be attached to the battery module. Fig. 5 is an exploded perspective view of the bus bar of Fig. 4. Fig. 6 is an enlarged view of a portion of Fig. 3, showing the bus bar of Fig. 3 attached to a bus bar frame.

[0038] Referring to FIG. 3, the battery module according to this embodiment includes a battery cell stack in which a plurality of battery cells 10 are stacked, electrode leads 11 protruding from one end or both ends of the battery cell stack, bus bars 100, and a bus bar frame 200.

[0039] First, the battery cell 10 is a secondary battery, and may be configured as, for example, a pouch-type secondary battery. A plurality of such battery cells 10 may be configured, and the plurality of battery cells 10 are stacked on each other so that they can be electrically connected to each other to form a battery cell stack.

[0040] The busbar 100 is welded to the electrode lead 11 and electrically connected to the electrode lead 11. The busbar frame 200 includes a plurality of slits 210, and the busbar 100 is arranged to correspond to the slits 210. The electrode lead 11 passes through the slits 210 and is joined to the busbar 100. The busbar frame 200 may be, for example, plastic injection molded, and may be made of a material commonly used for busbar frames 200.

[0041] 4 and 5, the bus bar 100 may be roughly composed of two layers: a bus bar body 110 electrically connected to the electrode lead 11, and a heat-resistant member 120.

[0042] The busbar body 110 is made of a metal material, for example, any one selected from copper, iron, aluminum, and alloys thereof. The busbar body 110 is joined to the electrode lead 11 by welding. The electrode lead 11 passes through the slit 130 of the busbar 100 or the space between adjacent busbars 100 and overlaps with one side of the busbar body 110 (the side facing the outside of the battery module). The electrode lead 11 and the busbar body 110 are electrically connected by welding the overlapping portion of the electrode lead 11 and the busbar body 110.

[0043] The heat-resistant member 120 is interposed between the busbar body 110 and the busbar frame 200. This prevents the risk of heat generated in the busbar body 110 during charging and discharging of the battery cells 10 being transferred to the injection-molded busbar frame 200, which could cause thermal deformation of the busbar frame 200.

[0044] More specifically, the busbar frame 200 is typically made of plastic. Conventionally, when the thickness of the busbar body 110 made of a metal material is reduced, more heat is generated in the busbar body 110 due to resistance, which may result in thermal deformation of the busbar frame 200. However, according to the present invention, by providing a heat-resistant member 120 between the busbar body 110 and the busbar frame 200, the heat generated in the busbar body 110 is prevented from being transferred to the busbar frame 200, thereby preventing thermal deformation of the busbar frame 200.

[0045] The heat-resistant member 120 may be formed in a plate shape and cover at least one surface of the busbar body 110. More specifically, the heat-resistant member 120 may cover the rear surface of the busbar body 110, which faces the busbar frame, among the two large-area surfaces (front and rear surfaces) of the busbar body 110. The size of the large surface of the heat-resistant member 120 may be the same as or larger than the size of the large surface of the busbar body 110. The slits 130 are integrally formed at the same position on the busbar body 110 and the heat-resistant member 120.

[0046] According to the prior art, the busbar 30 is hook-coupled to the busbar frame 20 by the fastening portion 22 (see FIG. 1) having a snap-fit ​​structure and a guide rib structure.

[0047] Meanwhile, according to one embodiment of the present invention, the busbar 100 is connected to the busbar frame 200 by heat fusion. That is, the fixing portion 22 having a snap-fit ​​structure and a guide rib structure in the busbar frame 200 is eliminated. Instead, as shown in Fig. 6, the busbar 100 is connected to the busbar frame 200 by the heat fusion portion 140. To this end, as shown in Figs. 4 to 6, at least one corner of the busbar body 110 is cut to expose the heat-resistant member 120. The heat fusion portion 140 may be made of the same material as the busbar frame 200.

[0048] The heat-resistant member 120 may be made of a material having a glass-transition temperature (Tg) higher than the maximum temperature rise of the busbar body 110. The heat-resistant member 120 may include, for example, a polymer having a middle or high glass-transition temperature (Tg).

[0049] The heat-resistant member 120 may have a high Tg (high glass transition temperature). The glass transition temperature of the heat-resistant member 120 may be, for example, 170°C or higher, or 170°C to 300°C, or 200°C to 250°C, or approximately 210°C to 220°C, or 210°C. Alternatively, the heat-resistant member 120 may include, for example, a high Tg FR-4 material, polysulfone, or polynorbornene. The high Tg FR-4 may have the properties shown in FIG. 7. For reference, FIG. 7 shows a comparison table of the properties of the high Tg FR-4 and the properties of FR-4.

[0050] Alternatively, in some cases, if the maximum temperature rise of the busbar body 110 is less than 140 degrees Celsius, the heat-resistant member 120 may have a high Tg (high glass transition temperature), but may also have a middle Tg (middle glass transition temperature). The heat-resistant member 120 may have a glass transition temperature of, for example, 150 degrees Celsius or higher, or, for example, 150 degrees Celsius or higher and 300 degrees Celsius or lower. In this case, the heat-resistant member 120 may include, for example, a middle Tg FR-4 material.

[0051] The busbar body 110 and the heat-resistant member 120 may be bonded together with an adhesive. The adhesive may be a heat-resistant adhesive, such as a heat-resistant epoxy adhesive. The adhesive may be provided in a sheet form or a paste form that is applied and then cured. If the adhesive is applied and then cured, it may be manufactured in a room temperature drying type, room temperature curing type, heat curing type, high temperature baking type, UV curing type, or the like.

[0052] When viewed from the front (when viewed from the outside of the busbar frame), the busbar body 110 and the heat-resistant member 120 have the same shape, and the busbar body 110 may further include a recess 111, which will be described later.

[0053] The heat-sealed portion 140 and the recess 111 may be provided at at least one of the corners of the bus bar 100, or may be provided at two diagonally opposite corners of the bus bar 100 as shown in Figures 4 to 6, or may be provided at all of the corners of the bus bar 100.

[0054] Meanwhile, as described above, a recess 111 is formed in at least one corner of the busbar body 110 so that the heat-sealing portion 140 can be provided, thereby exposing the heat-resistant member 120. For example, the recess 111 may have a recessed (indented) shape recessed from the periphery of the busbar body 110, and the recess 111 may have a rectangular or circular shape. As shown in FIGS. 4 to 6, the recess 111 may be formed in a rectangular shape with a 90-degree corner, for example. However, the present invention is not limited to the illustrated examples. It is sufficient that the heat-resistant member 120 is exposed and the heat-sealing portion 140 can be provided, and various shapes and structures may be used. For example, various modifications and variations are possible, such as chamfering the corners of the busbar body 110. The recess 111 may be formed by cutting the corner of the busbar body 110, or the busbar body 110 may be cast to have the shape of the recess 111.

[0055] The recess 111 of the busbar body 110 may be spaced a predetermined distance from the periphery of the recess 111 and the heat-sealed portion 140 so that the heat-sealed portion 140 is not affected by the heat generated by welding when the electrode lead 11 is welded to the busbar body 110.

[0056] Holes 121 are formed on the exposed surface of the heat-resistant member 120. The busbar 100 may be joined to the busbar frame 200 by heat fusion through the holes 121. The heat-sealing portion 140 may be formed by welding through the holes 121, for example. The busbar 100, in which the busbar body 110 and the heat-resistant member 120 are bonded with an adhesive, may be joined to the busbar frame 200 by heat fusion at the heat-sealing portion 140. Alternatively, the heat-resistant member 120 may be first joined to the busbar frame 200 by heat fusion, and then the adhesive may be applied to the heat-resistant member 120 and the busbar body 110 may be attached thereto.

[0057] According to such an embodiment of the present invention, it is possible to reduce the thickness by more than half compared to a conventional busbar made of a single metal material. For example, the thickness of the busbar body 110 may be 20% to 80%, 30% to 70%, or 40% to 60% of the overall thickness of the busbar 100 (the sum of the thicknesses of the busbar body 110 and the heat-resistant member 120).

[0058] Where a conventional busbar has a thickness of, for example, 3 mm, the thickness of the busbar body 110 can be reduced to, for example, 1.4 mm according to an embodiment of the present invention. In this case, the thickness of the heat-resistant member 120 can be, for example, 1.6 mm, but may be less than that.

[0059] The thickness can be the same or smaller than that of a conventional bus bar made of a single metal material, and above all, the amount of metal required to manufacture the bus bar can be reduced, thereby reducing overall manufacturing costs. At the same time, the functionality of the bus bar (electrode lead and electrical connection) can be maintained and deformation of the bus bar frame 200 due to the thermal resistance of the bus bar can be prevented.

[0060] The bus bar frame 200 shown in Fig. 3 is connected to end plates 40 to form a battery module. The stack of battery cells 10 can be housed in a module frame, or a module-less structure can be provided in which the module frame is omitted. The end plates 40 can be ordinary end plates.

[0061] The battery module may be included in a battery pack. The battery pack may include one or more battery modules according to the present embodiment, and may further include a battery management system (BMS) for managing the temperature and voltage of the battery, a cooling device, and the like.

[0062] The battery module and the battery pack including the same may be applied to various devices, such as transportation means such as electric bicycles, electric vehicles, and hybrid vehicles, and / or energy storage systems (ESS), but the present invention is not limited thereto and may be applied to various devices that can use the battery module and the battery pack including the same, which also fall within the scope of the present invention.

[0063] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the claims also fall within the scope of the present invention. [Explanation of symbols]

[0064] 10: Battery cell stack 11: Electrode lead 20: Busbar frame 30: Busbar 40: End plate 100: Busbar 110: Busbar body 120: Heat-resistant material 130: Slit 140: Heat-sealed part 200: Busbar frame 210: Slit

Claims

1. a battery cell stack in which a plurality of battery cells are stacked; a bus bar frame formed on one or both sides of the battery cell stack; and a bus bar on an outer surface of the bus bar frame, the bus bar being electrically connected to an electrode lead of the battery cell stack; The bus bar includes a bus bar body connected to the electrode lead, and a heat-resistant member interposed between the bus bar and the bus bar frame.

2. The battery module according to claim 1 , further comprising a heat-sealing portion that allows the heat-resistant member to be heat-sealed to the bus bar frame.

3. The battery module according to claim 2 , wherein at least one of the corners of the bus bar body includes a recess, and the heat-resistant member is exposed in the recess to provide the heat-sealed portion.

4. The battery module according to claim 3 , wherein the bus bar body and the heat-resistant member have the same shape when viewed from the front, and the bus bar body further includes the recess.

5. The battery module according to claim 3 , wherein the exposed heat-resistant member has a hole through which the heat-resistant member is joined to the bus bar frame.

6. The battery module according to claim 3 , wherein the heat-sealing portion is spaced a predetermined distance from a periphery of the recess of the bus bar body.

7. The battery module according to claim 3 , wherein the heat-sealing portion and the recessed portion of the bus bar body are provided at two corners of the bus bar that face each other diagonally.

8. The battery module according to claim 3 , wherein the heat-sealing portion is made of the same material as the bus bar frame.

9. the busbar body is made of a metal material, 2. The battery module according to claim 1, wherein the heat-resistant member is made of a material having a glass-transition temperature (Tg) higher than a maximum temperature rise during charging and discharging of the battery cells of the bus bar body.

10. The battery module according to claim 1 , wherein the heat-resistant member comprises a polymer having a middle or high glass transition temperature (Tg).

11. The battery module according to claim 1 , wherein the bus bar body and the heat-resistant member are bonded to each other with an adhesive.

12. The battery module according to claim 11 , wherein the adhesive is a heat-resistant epoxy adhesive.

13. The battery module of claim 1 , wherein the thickness of the bus bar body is 20% to 80% of the thickness of the entire bus bar.

14. The battery module according to claim 1 , wherein the bus bar includes a slit through which the electrode lead passes, the slit being integrally formed at the same position on the bus bar body and the heat-resistant member.

15. A battery pack comprising the battery module according to claim 1.

16. 16. An energy storage system comprising the battery pack of claim 15.

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