Battery cell and battery module including the same

Abstract

The present invention includes a battery cell and a battery module including the same. The battery cell according to one embodiment of the present invention includes an electrode assembly including a positive electrode, a negative electrode, and a separator; a battery case including a receiving portion for receiving the electrode assembly; and a flame-retardant member located on the outer surface of the battery case, the receiving portion being a region of the battery case that is formed to protrude toward the outside of the battery case.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0134796, filed on October 11, 2023, and all contents disclosed in the documents of this Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a battery cell and a battery module including the same, and more particularly to a battery cell having enhanced durability and improved safety, and a battery module including the same. [Background technology]

[0003] With the technological development and increasing demand for mobile devices, the demand for secondary batteries as an energy source is rapidly increasing. As a result, research into secondary batteries that can meet various needs is actively being conducted.

[0004] Secondary batteries are attracting much attention as an energy source not only for mobile devices such as mobile phones, digital cameras, and laptop computers, but also for power devices such as electric bicycles, electric vehicles, and hybrid electric vehicles.

[0005] In recent years, the need for large-capacity secondary battery structures has increased, including the use of secondary batteries as energy storage sources, and there has been an increase in demand for battery packs with medium to large modular structures that combine battery modules in which multiple secondary batteries are connected in series or parallel.

[0006] Meanwhile, when a battery pack is constructed by connecting a plurality of battery cells in series / parallel, a battery module consisting of at least one battery cell is generally constructed, and other components are added to the at least one battery module to construct the battery pack. The battery cells that make up such a medium- to large-sized battery module are composed of secondary batteries that can be charged and discharged. Such high-power, large-capacity secondary batteries generate a large amount of heat during the charging and discharging process, which can vaporize the electrolyte, increase internal pressure, and cause the battery cell pouch to burst.

[0007] FIG. 1 is a diagram showing a conventional battery cell.

[0008] 1, a conventional battery cell 10 includes an electrode assembly and a battery case 30 that houses the electrode assembly. In this case, since the electrode assembly, which has a certain thickness, is housed inside the battery case 30, one side of the battery case 30 is molded to protrude outward, and one area of ​​the molded battery case 30 is a protrusion 31.

[0009] In such a conventional battery cell 10, a region of the battery case 30 may be ruptured due to heat generated during the charging and discharging process of the battery. Specifically, the heat generated during charging and discharging of the battery causes the electrolyte to evaporate, increasing the internal pressure of the battery case 30, which may cause a region of the battery case 30 to rupture and release venting gas to the outside. In this case, the battery case 30 may rupture indiscriminately without any particular direction, but generally, the protrusion 31, which is relatively less durable than other regions of the battery case 30, is more likely to rupture.

[0010] Specifically, the protruding portion 31 of the battery case 30 that protrudes outward is molded to be thinner than an unmolded area of ​​the battery case 30, which reduces durability. Therefore, under the same circumstances, the protruding portion 31 of the battery case 30 is more likely to break than other areas, and venting gas may be released to the outside.

[0011] Therefore, when venting occurs in one battery cell, high-temperature gas may move to adjacent battery cells, causing thermal runaway in the battery and reducing the safety of the battery. Therefore, there is an increasing need to solve this problem. Summary of the Invention [Problem to be solved by the invention]

[0012] The problem to be solved by the present invention is to provide a battery cell with improved durability and safety, and a battery module including the same.

[0013] 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]

[0014] A battery cell according to one embodiment of the present invention includes an electrode assembly including a positive electrode, a negative electrode, and a separator; a battery case including a receiving portion for receiving the electrode assembly; and a flame-retardant member located on an outer surface of the battery case, the receiving portion being a region of the battery case that is formed to protrude toward the outside of the battery case.

[0015] The flame retardant member may be provided on the storage section.

[0016] The storage portion may include a corner portion that is an edge region of the storage portion, and a first surface and a second surface that share the corner portion.

[0017] The first surface may be a surface that protrudes toward an outer surface of the battery case, and the second surface may be a surface that is positioned perpendicular to the first surface.

[0018] The flame retardant member may be positioned to cover the corner.

[0019] The flame retardant member may be positioned to cover the first surface and the second surface.

[0020] The flame-retardant members may be connected to each other and positioned to form one area on the receiving portion.

[0021] The flame-retardant member may be coated on the battery case with a uniform thickness.

[0022] The flame-retardant member may be uniformly applied to a thickness of 1 mm or more on the battery case.

[0023] The flame-retardant member may include a material that has flame retardancy and adhesive properties.

[0024] The flame-retardant member may include at least one of an epoxy-based resin and a silicone-based resin.

[0025] The flame-retardant member may be applied to the battery case, cured, and adhered to and fixed on the battery case.

[0026] A battery module according to another embodiment of the present invention includes the above-described battery cells. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a diagram showing a conventional battery cell. [Figure 2] 1 is a perspective view of a battery cell according to an embodiment of the present invention. [Figure 3] FIG. 2 is an exploded perspective view of a battery cell according to an embodiment of the present invention. [Figure 4] FIG. 3 is an enlarged view showing A1 in FIG. 2. [Figure 5] FIG. 5 is a cross-sectional view taken along the line BB' in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention may be embodied in several different forms and is not limited to the embodiments set forth herein.

[0029] To clearly describe the present invention, portions unnecessary for the description will be omitted and the same reference numerals will be used throughout the specification to refer to the same or similar components.

[0030] In addition, 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. Thicknesses are exaggerated to clearly show various layers and regions in the drawings. In addition, in the drawings, the thicknesses of some layers and regions are exaggerated for the convenience of explanation.

[0031] Furthermore, when a layer, film, region, plate, or other part is said to be "on" or "above" another part, this includes not only the case where it is "directly above" that other part, but also the case where there is another part in between. Conversely, when a part is said to be "directly above" another part, it means that there is no other part in between. Furthermore, being "on" or "above" a reference part means being located above or below the reference part, and does not necessarily mean being located "on" or "above" in the opposite direction of gravity.

[0032] Furthermore, throughout the specification, when a part is said to "comprise" a certain element, this means that it may further include other elements, rather than excluding other elements, unless otherwise specified.

[0033] Also, throughout the specification, "on a plane" means a view of the subject part from above, and "on a cross section" means a view of the subject part cut vertically from the side.

[0034] Furthermore, the terms "first" and "second" used in this application can be used to describe various components, but the components should not be limited by the terms. The terms are used only to distinguish one component from another.

[0035] Here, the "side direction" refers to the direction toward the center of the battery cell, and the "outside direction" refers to the direction toward the outside of the battery cell. From the same perspective, the "inside" refers to a surface toward the center of the battery cell, and the "outside" refers to a surface facing the inside and toward the outside. In this specification, the terms "inside" and "outside" are used interchangeably unless otherwise specified.

[0036] Fig. 2 is a perspective view of a battery cell according to an embodiment of the present invention, and Fig. 3 is an exploded perspective view of a battery cell according to an embodiment of the present invention.

[0037] 2 and 3, a battery cell 100 according to an embodiment of the present invention includes an electrode assembly 200 including a positive electrode, a negative electrode, and a separator, a battery case 300 having a receiving portion 310 for receiving the electrode assembly 200, and a flame-retardant member 400 applied to the outer surface of the battery case 300.

[0038] The electrode assembly 200 may be a stacked electrode assembly 200 in which a plurality of positive and negative electrodes cut into a certain size are stacked in order with a separator interposed therebetween, but is not limited thereto, and may be a winding-type assembly in which a stacked structure of positive and negative electrodes with a separator interposed therebetween is wound up.

[0039] The electrode lead 210 is electrically connected to the electrode assembly 200. Such electrode leads 210 may be provided in pairs. Portions of the pair of electrode leads 210 may protrude outward from the battery case 300 toward the front and rear (both ends in the longitudinal direction of the electrode assembly, in the x-axis direction or the -x-axis direction) of the battery case 300. The configuration of the battery cell 100 described above is an example, and the shape of the battery cell 100 may be modified in various ways.

[0040] The battery case 300 may include a storage portion 310, a sealing portion 320, and a folding portion 330. The battery case 300 may include a first region 301 and a second region 302 that correspond to each other, and may be made of a sheet-like base material including a first storage portion 310a located in the first region 301, a second storage portion 310b located in the second region 302, and a folding portion 330 located between the first storage portion 310a and the second storage portion 310b.

[0041] The first region 301 and the second region 302 may be separated by a fold 330. The first region 301 and the second region 302 may be separated by a central region of the fold 330 that extends in the x-axis direction.

[0042] During manufacturing of the battery case 300, a receiving portion 310 for receiving the electrode assembly 200 may be formed in at least one of the first region 301 and the second region 302 by forming. That is, the receiving portion 310 may be a region of the battery case 300 formed to protrude toward the outside of the battery case 300 in order to receive the electrode assembly 200.

[0043] The storage section 310 may include a first storage section 310a located in the first region 301 and a second storage section 310b located in the second region 302. Each of the first storage section 310a and the second storage section 310b houses a portion of the electrode assembly 200, and the first storage section 310a and the second storage section 310b may be folded to face each other with the folding section 330 therebetween, thereby surrounding and storing the electrode assembly 200.

[0044] After the receiving portion 310 is formed, the folding portion 330 of the battery case 300 can be bent 180 degrees based on the center of the folding portion 330 extending in the x-axis direction to cover the receiving portion 310, thereby completing the battery case 300 structure.

[0045] The folding portion 330 may be a portion for bending the battery case 300. The first region 301 and the second region 302 may correspond to and contact each other along the center of the folding portion 330 extending in the x-axis direction.

[0046] The electrode assembly 200 has a four-sided planar shape, and the folding portion 330 may be located at a portion corresponding to one of the four sides. Specifically, the folding portion 330 is closely attached to one side 230 of the electrode assembly 200, and the sheet-like base material is folded at both edges of the folding portion 330, so that the first and second receiving portions 310a and 310b face each other. Therefore, the width (P) of the folding portion 330 is the same as the thickness (t) of the electrode assembly 200.

[0047] The edges of the first receiving portion 310a and the second receiving portion 310b are joined together on three sides excluding the side corresponding to the folding portion 330 to form a sealing portion 320. The sealing portion 320 is sealed by a method such as heat sealing.

[0048] More specifically, the sheet-shaped base material of the battery case 300 is made of a laminate sheet including a metal layer and a resin layer. In particular, the laminate sheet may be an aluminum laminate sheet. The sheet-shaped base material includes a core made of a metal layer, a heat-sealing layer formed on one surface of the core, and an insulating film formed on one surface of the core.

[0049] The heat-sealing layer is made of modified polypropylene, such as cast polypropylene (CPP), which is a polymer resin, and acts as an adhesive layer. The insulating film is made of a resin material such as nylon or polyethylene terephthalate (PET), but the structure and material of the pouch exterior material are not limited thereto.

[0050] In the sealing part 320, the heat-sealing layers of the first receiving part 310a and the second receiving part 310b are in contact with each other, and the battery case 300 is sealed by performing a heat-sealing process in this contact state.

[0051] The sealing portion 320 may include a first sealing portion 321 , a second sealing portion 325 and a third sealing portion 327 .

[0052] The first sealing portion 321 and the second sealing portion 325 may be sealing portions 320 located on both sides (x-axis direction or -x-axis direction) of the battery case 300. The first sealing portion 321 may be an edge of one side of the battery case 300, and the second sealing portion 325 may be an edge of the other side of the battery case 300. The first sealing portion 321 and the second sealing portion 325 may be sealing portions 320 where the electrode lead 210 is located.

[0053] The third sealing portion 327 may be a portion of the sealing portion 320 facing the folded portion 330. The third sealing portion 327 may be an edge of the sealing portion 320 facing the folded portion 330. The third sealing portion 327 may be a portion of the sealing portion 320 where the electrode lead 210 is not located.

[0054] After the sealing unit 320 is completely sealed, if the battery cell 100 is in a high temperature state, the electrolyte present inside the battery cell 100 may evaporate, causing an increase in the internal pressure of the battery cell 100 and causing the battery cell 100 to expand, which may cause the sealed battery case 300 to break. In this case, the battery case 300 may break, causing high-temperature particles and gas inside the battery cell 100 to burst, and additional heat may be transferred to the sealing unit 320 to provide directionality to the bursting of the particles and gas.

[0055] The flame-retardant member 400 may be provided on the outer surface of the battery case 300. The flame-retardant member 400 is provided in one region of the outer surface of the battery case 300, and specifically, the flame-retardant member 400 is provided in the storage section 310.

[0056] The flame-retardant member 400 may be a flame-retardant and adhesive material that is applied to the battery case 300, cured, and adhered to and fixed on the battery case 300. For example, the flame-retardant member 400 may be an epoxy resin.

[0057] The flame-retardant member 400 is additionally provided on the outer surface of the battery case 300, thereby ensuring the thickness of the battery case 300 and improving the durability of the battery. Therefore, during charging and discharging of the battery, the frequency with which venting gas breaks the battery case 300 and is released to the outside is reduced compared to conventional methods, thereby ensuring the safety of the battery.

[0058] The flame-retardant member 400 will be described in detail below.

[0059] Fig. 4 is an enlarged view showing A1 in Fig. 2. Fig. 5 is a cross-sectional view taken along line BB' in Fig. 4.

[0060] The battery cell 100 according to the embodiment of the present invention includes a flame-retardant member 400 provided on the outer surface of the receiving portion 310 of the battery case 300 .

[0061] The flame-retardant member 400 is located in a region of the battery case 300 formed to accommodate the electrode assembly, and may be applied to a portion of the battery case 300 where durability is weakened.

[0062] Specifically, the flame-retardant member 400 is provided in an edge region of the storage section 310 that protrudes outward. More specifically, the flame-retardant member 400 is provided in a corner portion 311 that is a protruding edge region of the storage section 310.

[0063] The corner 311 may be an edge region that determines the overall shape of the receiving portion 310, which is a region of the battery case 300 that protrudes outward. The corner 311 has a shape corresponding to the shape of the electrode assembly and may be formed on the battery case 300. In the present invention, the corner 311 corresponds to a rectangle, but is not limited thereto.

[0064] The flame retardant member 400 may be applied to and positioned in an area of ​​the receiving portion 310 including the corner portion 311 .

[0065] The receiving portion 310 may include a first surface 312 and a second surface 313 that share a corner 311. Here, the first surface 312 may refer to a surface that protrudes toward the outer surface of the battery case 300, and the second surface 313 may refer to a side surface that is perpendicular to the first surface 312.

[0066] The flame retardant member 400 may be positioned on the corners 311, the first surface 312, and the second surface 313 of the storage section 310. In this case, the flame retardant member 400 may be positioned to cover the entire first surface 312, or may be positioned to cover only a partial area of ​​the first surface 312 as shown in the drawing. The flame retardant member 400 may be positioned to cover the entire second surface 313 as shown in the drawing, or may be positioned to cover only a partial area of ​​the second surface 313.

[0067] However, since the corners 311 of the storage section 310 are formed to have the thinnest thickness when the battery case 300 is formed, the flame-retardant member 400 must be additionally applied to the corners 311 to ensure the durability of the battery. Therefore, the flame-retardant member 400 must be positioned on the first surface 312 and the second surface 313, which include and are connected to the corners 311.

[0068] In other words, the flame-retardant member 400 may be connected and positioned to form one area on the receiving portion 310. However, the flame-retardant member 400 may be applied to an area where durability needs to be further enhanced after being applied as described above.

[0069] Such flame-retardant member 400 may be uniformly applied to corners 311, first surface 312, and second surface 313. For example, flame-retardant member 400 may be uniformly applied and positioned with a thickness of 1 mm or more. Therefore, when battery cells are stacked to form a battery module or a battery pack, the stacking rate may be improved while reducing assembly tolerances within the module or pack case.

[0070] The flame-retardant member 400 may include a flame-retardant epoxy resin, which may be one that satisfies the flame-retardant evaluation standard UL-94 test. Specifically, the flame-retardant member 400 may include, but is not limited to, an aromatic-based flame-retardant epoxy resin, which is a common flame-retardant epoxy resin, and may also include a silicone-based resin. That is, the flame-retardant member 400 may include at least one of an epoxy-based resin and a silicone-based resin. The flame-retardant resin may have a heat resistance temperature of at least 150°C.

[0071] In summary, by additionally positioning the flame-retardant member 400 on the outer surface of the receiving portion 310 of the battery case 300, it is possible to improve the durability of a region of the battery case 300 that has been weakened due to a reduction in thickness caused by molding the battery case 300. Therefore, even if the internal pressure of the battery case 300 increases due to the vaporization of the electrolyte caused by heat generated during charging and discharging of the battery, it is possible to prevent the battery case 300 from breaking and venting gas from being discharged to the outside, thereby preventing thermal runaway and improving the safety of the battery.

[0072] Furthermore, the flame-retardant member 400 is applied to the outer surface of the battery case 300 with a uniform thickness, but is not applied to the inner surface of the battery case 300, so that it does not affect the energy density of the battery. That is, the flame-retardant member 400 is not applied to the inner surface of the housing 310 in which the electrode assembly is housed, so that it does not affect the energy density of the electrode assembly. Therefore, the durability of the battery case 300 is improved, the energy density of the battery can be maintained, and the safety of the battery can be more effectively ensured.

[0073] The battery cells and battery modules including the same can be applied to battery packs and various devices, such as electric bicycles, electric cars, hybrid cars, and other means of transportation, but the present invention is not limited thereto and can be applied to various devices that can use battery modules and battery packs including the same, which also fall within the scope of the present invention.

[0074] 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 following claims also fall within the scope of the present invention. [Industrial Applicability]

[0075] According to the embodiment, the battery cell of the present invention can improve the safety of the battery cell by strengthening the durability of the battery case.

[0076] Furthermore, according to the embodiment, the battery cell of the present invention can ensure the energy density of the battery by ensuring the space for accommodating the electrode assembly.

[0077] The effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims. [Explanation of symbols]

[0078] 100 battery cells 200 Electrode Assembly 300 Battery Case 310 Storage section 310a First storage section 310b Second storage section 311 Corner 312 1st page 313 2nd page 320 Sealing section 330 Folding section 400 Flame retardant materials

Claims

1. an electrode assembly including a positive electrode, a negative electrode, and a separator; a battery case including a housing for housing the electrode assembly; and a flame-retardant member located on an outer surface of the battery case; The battery cell, wherein the storage portion is a region of the battery case that is formed to protrude toward the outside of the battery case.

2. The battery cell according to claim 1 , wherein the flame-retardant member is provided on the housing portion.

3. The storage section is a corner portion that is an edge region of the storage portion; and The battery cell of claim 1 , comprising a first surface and a second surface that share the corner.

4. the first surface is a surface that protrudes toward an outer surface of the battery case, The battery cell according to claim 3 , wherein the second surface is a surface positioned perpendicular to the first surface.

5. The battery cell according to claim 3 , wherein the flame-retardant member is positioned to cover the corner portion.

6. The battery cell according to claim 5 , wherein the flame-retardant member is positioned to cover the first surface and the second surface.

7. The battery cell according to claim 6 , wherein the flame-retardant member is connected to form one area on the receiving portion.

8. The battery cell according to claim 1 , wherein the flame-retardant member is applied to the battery case with a uniform thickness.

9. The battery cell according to claim 8 , wherein the flame-retardant member is uniformly applied to the battery case to a thickness of 1 mm or more.

10. The battery cell according to claim 1 , wherein the flame-retardant member includes a material that is flame-retardant and adhesive.

11. The battery cell according to claim 10 , wherein the flame-retardant member includes at least one of an epoxy-based resin and a silicone-based resin.

12. The battery cell according to claim 1 , wherein the flame-retardant member is applied onto the battery case, hardened, and adhered and fixed to the battery case.

13. A battery module comprising the battery cell according to any one of claims 1 to 12.

Images