Battery cell with improved structure and battery module containing the same

Abstract

This disclosure relates to a battery cell with an improved structure and a battery module including the same, more particularly to a battery cell and a battery module including the same, characterized in that it includes an electrode assembly having electrode tabs protruding and including a positive electrode, a separator membrane, and a negative electrode; a pair of cover separator membranes, consisting of a first cover separator membrane and a second cover separator membrane, positioned to surround the electrode assembly; a pouch case housing the electrode assembly and the pair of cover separator membranes; electrode leads, one end of which is connected to the electrode tabs and the other end protruding to the outside of the pouch case; and an insulating film positioned between the pouch case and the electrode leads.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0033077 filed on March 8, 2024, and all the contents disclosed in the Korean Patent Application are included as part of this specification.

[0002] The present disclosure relates to a battery cell with an improved structure and a battery module including the same, and specifically, to a battery cell with an improved structure and a battery module including the same, which can prevent the occurrence of defects due to height deviation by position of the battery cell, and includes a cover separation film surrounding the electrode assembly.

Background Art

[0003] In recent years, due to air pollution caused by the use of fossil fuels and the development of alternative energy due to energy depletion, the demand for secondary batteries that can store the generated electrical energy has been increasing.

[0004] As an energy source for various electronic devices that are essential and indispensable in modern society, secondary batteries have an increasing required capacity due to the increasing use and complexity of mobile devices and the development of electric vehicles, etc. To meet the needs of users, a large number of battery cells are arranged in small devices, while in vehicles, etc., a battery module that electrically connects a large number of battery cells or a battery pack including a large number of such battery modules is used.

[0005] On the other hand, in the manufacturing process of battery cells, in order to fix the electrode assembly formed by laminating the positive electrode, negative electrode, and separation membrane, a tape made of a PET material or the like is attached to a part of the electrode assembly for fixation.

[0006] FIG. 1 is a cross-sectional view showing a cell assembly for a pouch-type secondary battery according to the prior art. As shown in FIG. 1, in the cell assembly 1 for a secondary battery according to the prior art, electrode plates 10 and 20 and a separation membrane 30 are laminated, and the separation membranes 30 arranged on the outermost layer and the lowermost layer are fixed using a plurality of tapes 50.

[0007] In this type of tape-based fixing, the tape is attached so as to surround a portion of the top, side, and bottom surfaces of the electrode assembly, and because it is located on a portion of the top and bottom surfaces, positional height deviations occur in the electrode assembly.

[0008] Furthermore, the adhesive layer of the tape reacts with the electrolyte, causing problems such as browning of the separation membrane and depletion of the electrolyte. If the gas generated by the use of the battery cell is collected in the terrace area inside the pouch case before reaching the critical point, the gas may penetrate between the secondary battery cell assembly 1, causing a widening of the space between the electrode plates 10, 20 and the separation membrane 30. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Korean Patent Publication No. 10-1951783 [Overview of the project] [Problems that the invention aims to solve]

[0010] To solve the aforementioned problems, this disclosure aims to provide a battery cell and a battery module including the same, which have an improved structure that prevents the gaps between the electrode assemblies from widening due to gas generated within the battery cell, thereby suppressing positional height deviations, by providing a cover separation membrane that surrounds the electrode assemblies. [Means for solving the problem]

[0011] A battery cell according to the present disclosure for achieving the aforementioned objectives is characterized by comprising: an electrode assembly (100) having an electrode tab (110) protruding and including a positive electrode, a separator membrane, and a negative electrode; a pair of cover separator membranes (200) positioned to surround the electrode assembly (100) and consisting of a first cover separator membrane (210) and a second cover separator membrane (220); a pouch case (300) housing the electrode assembly (100) and the pair of cover separator membranes (200); an electrode lead (400) having one end connected to the electrode tab (110) and the other end protruding to the outside of the pouch case; and an insulating film (500) positioned between the pouch case (300) and the electrode lead (400).

[0012] Furthermore, in the battery cell according to this disclosure, the first cover separator membrane (210) includes a first side portion (211) that is in close contact with one side surface of the electrode assembly (100), a first upper portion (212) that is in close contact with a part of the upper surface of the electrode assembly (100), and a first lower portion (213) that is in close contact with a part of the lower surface of the electrode assembly (100), and the second cover separator membrane (220) includes a second side portion (221) that is in close contact with the other side surface of the electrode assembly (100), a second upper portion (222) that is in close contact with a part of the upper surface of the electrode assembly (100), and a second lower portion (223) that is in close contact with a part of the lower surface of the electrode assembly (100).

[0013] Furthermore, in the battery cell according to this disclosure, the first side portion (211) is formed with a first through-hole (211') through which the electrode tab (110) provided on one side of the electrode assembly (100) passes, and the second side portion (221) is formed with a second through-hole (221') through which the electrode tab (110) provided on the other side of the electrode assembly (100) passes.

[0014] Furthermore, in the battery cell according to this disclosure, the sum of the lengths (in the Y-axis direction) of the first upper portion (212) and the second upper portion (222) is the same as the length (in the Y-axis direction) of the electrode assembly (100), and the sum of the lengths (in the Y-axis direction) of the first lower portion (213) and the second lower portion (223) is the same as the length (in the Y-axis direction) of the electrode assembly (100).

[0015] Furthermore, in the battery cell according to this disclosure, the length (in the Y-axis direction) of each of the first upper portion (212), the second upper portion (222), the first lower portion (213), and the second lower portion (223) is half the length (in the Y-axis direction) of the electrode assembly (100).

[0016] Furthermore, in the battery cell according to this disclosure, the separation membrane and the cover separation membrane (200) are made of the same material.

[0017] Furthermore, in the battery cell according to this disclosure, the first cover separator membrane (210) and the second cover separator membrane (220) are characterized in that the portions in contact with each other are connected.

[0018] Furthermore, in the battery cell according to this disclosure, the width (in the X-axis direction) of the first cover separator membrane (210) and the second cover separator membrane (220) is greater than or equal to the width (in the X-axis direction) of the electrode assembly (100).

[0019] Furthermore, in the battery cell according to this disclosure, the portions of the first cover separator membrane (210) and the second cover separator membrane (220) that are in contact with each other are connected via an adhesive member.

[0020] Furthermore, in the battery cell according to this disclosure, the portions of the first cover separation membrane (210) and the second cover separation membrane (220) that are in contact with each other are connected by a lamination process.

[0021] Furthermore, this disclosure may be a battery module including the aforementioned battery cells.

Advantages of the Invention

[0022] As described above, the battery cell with an improved structure according to the present disclosure and the battery module including the same have the advantage that the generation of height deviation by position can be suppressed because the cover separation film surrounds the entire upper and lower surfaces of the electrode assembly.

[0023] Further, according to the battery cell and the battery module including the same according to the present disclosure, since the cover separation film surrounds the side surface provided with the electrode tab of the electrode assembly, there is an advantage that gas generated in the battery cell can be prevented from penetrating from the terrace portion into the electrode assembly.

Brief Description of the Drawings

[0024] [Figure 1] It is a cross-sectional view showing a cell assembly for a pouch-type secondary battery according to the prior art.

[0025] [Figure 2] It is an exploded perspective view showing a battery cell according to a preferred embodiment of the present disclosure.

[0026] [Figure 3] It is an exploded perspective view showing an electrode assembly of a battery cell according to a preferred embodiment of the present disclosure.

[0027] [Figure 4] It is a cross-sectional view showing a battery cell according to a preferred embodiment of the present disclosure.

Modes for Carrying Out the Invention

[0028] Hereinafter, embodiments that enable a person having ordinary knowledge in the technical field to which the present disclosure pertains to easily implement the present disclosure will be described in detail with reference to the accompanying drawings. However, when it is determined that a detailed description of related known functions or configurations may unnecessarily obscure the gist of the present disclosure in explaining the operating principle of the preferred embodiment of the present disclosure, the detailed description thereof will be omitted.

[0029] Furthermore, the same reference numerals shall be used throughout the drawings for parts that have similar functions and operations. Throughout the specification, when it is said that one part is connected to another part, this includes not only direct connections but also indirect connections through other elements in between. Also, when it is said that a component is included, unless otherwise stated, it does not mean that other components are excluded, but rather that other components may be included.

[0030] The battery cell with the improved structure described herein and the battery module including it will be described below with reference to the attached drawings.

[0031] Figure 2 is an exploded perspective view showing a battery cell according to a preferred embodiment of the present disclosure, Figure 3 is an exploded perspective view showing an electrode assembly of a battery cell according to a preferred embodiment of the present disclosure, and Figure 4 is a cross-sectional view showing a battery cell according to a preferred embodiment of the present disclosure.

[0032] Referring to Figures 2 to 4, a battery cell according to a preferred embodiment of the present disclosure includes an electrode assembly 100, a cover separator membrane 200, a pouch case 300, electrode leads 400, and an insulating film 500.

[0033] First, the electrode assembly 100 has a structure in which positive and negative electrodes are repeatedly stacked alternately with a separator membrane in between. A pair of electrode leads 400, consisting of a positive lead and a negative lead, are electrically connected to the positive tab and the negative tab, and then exposed to the outside of the pouch case 300.

[0034] The positive electrode is manufactured by coating a positive electrode mixture containing positive electrode active material onto a positive electrode current collector and then drying it. The positive electrode mixture may optionally further contain binders, conductive agents, fillers, etc.

[0035] The positive electrode current collector can generally have a thickness of 3 μm to 500 μm. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes to the battery, and can be made of, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc. Furthermore, the positive electrode current collector can have fine irregularities formed on its surface to enhance the adhesion of the positive electrode active material, and can take various forms such as film, sheet, foil, net, porous material, foam, and nonwoven fabric.

[0036] The positive electrode active material is a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7; chemical formula LiNi 1-x Ni-site type lithium nickel oxide represented as MxO2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 to 0.3); chemical formula LiMn 2-x M x Lithium manganese composite oxides represented as O2 (where M = Co, Ni, Fe, Cr, Zn, or Ta, and x = 0.01 to 0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu, or Zn); LiMn2O4 in which part of the Li in the chemical formula is replaced with an alkaline earth metal ion; disulfide compounds; Fe2(MoO4)3, etc. are examples, but are not limited to these.

[0037] The negative electrode is manufactured by coating a negative electrode mixture containing negative electrode active material onto a negative electrode current collector and then drying it. The negative electrode mixture may optionally contain components such as conductive agents, binders, and fillers.

[0038] Negative electrode current collectors are generally manufactured to a thickness of 3 μm to 500 μm. Such negative electrode current collectors are not particularly limited as long as they have high conductivity without causing chemical changes to the battery. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper stainless steel with surface treatment of carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloys can be used. Also, similar to positive electrode current collectors, fine irregularities can be formed on the surface to strengthen the bonding force of the negative electrode active material, and various forms such as films, sheets, foils, nets, porous materials, foams, and nonwoven fabrics can be used.

[0039] The separation membrane uses an insulating thin film with high ion permeability and mechanical strength to prevent short circuits between the negative and positive electrodes, allowing only the movement of lithium ions. The pore diameter of the separation membrane is generally 0.01 μm to 10 μm, and the thickness is generally 5 to 300 μm. The material of such a separation membrane is preferably, but not limited to, one selected from polyethylene, polypropylene, polyethylene / polypropylene bilayer, polyethylene / polypropylene / polyethylene triple layer, polypropylene / polyethylene / polypropylene triple layer, and organic fiber filter paper.

[0040] On the other hand, the negative electrode current collector and the positive electrode current collector are composed of a portion coated with a slurry containing an active material and a plain portion where the slurry is not coated. The plain portion is cut to form an electrode tab 110, or a separate conductive member is attached to the plain portion by ultrasonic welding or the like to form an electrode tab 110, and these electrode tabs 110 are gathered together to form a tab bundle.

[0041] The cover separation membrane 200 surrounds the electrode assembly 100 and includes a first cover separation membrane 210 and a second cover separation membrane 220.

[0042] The cover separation membrane 200 is made of the same material as the separation membrane included in the electrode assembly 100, and is preferably, but not limited to, one of the following materials: polyethylene, polypropylene, polyethylene / polypropylene double layer, polyethylene / polypropylene / polyethylene triple layer, polypropylene / polyethylene / polypropylene triple layer, and organic fiber filter paper.

[0043] The portions of the first cover separation membrane 210 and the second cover separation membrane 220 that are in contact with each other may be connected. These contact portions may be connected via an adhesive member or by a lamination process, and the method of connection is not particularly limited as long as it does not cause positional height (Z-axis direction) deviations of the electrode assembly 100 surrounded by the first cover separation membrane 210 and the second cover separation membrane 220.

[0044] The width (in the X-axis direction) of the first cover separation membrane 210 and the second cover separation membrane 220 may be formed to be greater than or equal to the width (in the X-axis direction) of the electrode assembly 100. This is because if the width (in the X-axis direction) of the first cover separation membrane 210 and the second cover separation membrane 220 is less than the width (in the X-axis direction) of the electrode assembly 100, there may be a portion on the upper or lower surface of the electrode assembly 100 that is not surrounded by the first cover separation membrane 210 and the second cover separation membrane 220, and the unsurrounded portion may have a relatively lower height (in the Z-axis direction), which may cause a height deviation.

[0045] Next, the first cover separation membrane 210 is positioned to surround a portion of one side of the electrode assembly 100 and includes a first side portion 211 that is in close contact with one side of the electrode assembly 100 on which the electrode tab 110 protrudes, a first upper portion 212 that is in close contact with a portion of the upper surface of the electrode assembly 100, and a first lower portion 213 that is in close contact with a portion of the lower surface of the electrode assembly 100.

[0046] Since the first side portion 211 is in close contact with one side of the electrode assembly 100 on which the electrode tab 110 is formed, a first through-hole 211' can be formed through which the electrode tab 110 can pass.

[0047] The first side portion 211 is positioned in close contact with one side of the electrode assembly 100, so that it can be located in one side terrace portion T inside the battery cell.

[0048] Here, the first side portion 211 can prevent gas generated by charging and discharging the battery cell from accumulating on the terrace portion T, and from penetrating in the direction of the electrode assembly 100.

[0049] The second cover separation membrane 220 is positioned to surround a portion of the other side of the electrode assembly 100 and includes a second side portion 221 that is in close contact with the other side of the electrode assembly 100 on which the electrode tab 110 protrudes, a second upper portion 222 that is in close contact with a portion of the upper surface of the electrode assembly 100, and a second lower portion 223 that is in close contact with a portion of the lower surface of the electrode assembly 100.

[0050] Since the second side portion 221 is in close contact with the other side of the electrode assembly 100 on which the electrode tab 110 is formed, a second through-hole 221' can be formed through which the electrode tab 110 can pass.

[0051] Since the second side portion 221 is located in close contact with one side of the electrode assembly 100, it may be located in the other side terrace portion T inside the battery cell.

[0052] Here, the second side portion 221, similar to the first side portion 211 described above, can prevent gas generated by charging and discharging of the battery cell, which may accumulate in the terrace portion T, from penetrating towards the electrode assembly 100.

[0053] It is preferable that the sum of the lengths (in the Y-axis direction) of the first upper portion 212 and the second upper portion 222 is the same as the length (in the Y-axis direction) of the electrode assembly 100. This is because if the sum of the lengths (in the Y-axis direction) of the first upper portion 212 and the second upper portion 222 is shorter than the length (in the Y-axis direction) of the electrode assembly 100, the height (in the Z-axis direction) of the portion not surrounded by the first upper portion 212 and the second upper portion 222 may be relatively low, resulting in a height (in the Z-axis direction) deviation.

[0054] Conversely, if the sum of the lengths (in the Y-axis direction) of the first upper portion 212 and the second upper portion 222 is longer than the length (in the Y-axis direction) of the electrode assembly 100, then an overlapping portion of the first upper portion 212 and the second upper portion 222 will occur, and the height (in the Z-axis direction) of the overlapping portion will be relatively high, which may cause a height (in the Z-axis direction) deviation.

[0055] Furthermore, it is preferable that the sum of the lengths (in the Y-axis direction) of the first lower portion 213 and the second lower portion 223 is the same as the length (in the Y-axis direction) of the electrode assembly 100. This is because if the sum of the lengths (in the Y-axis direction) of the first lower portion 213 and the second lower portion 223 is shorter than the length (in the Y-axis direction) of the electrode assembly 100, the height (in the Z-axis direction) of the portion not surrounded by the first lower portion 213 and the second lower portion 223 will be relatively low, which may cause a height (in the Z-axis direction) deviation.

[0056] Conversely, First lower surface part 213 and second lower surface part 223 If the sum of the lengths (in the Y-axis direction) is longer than the length (in the Y-axis direction) of electrode assembly 100, First lower surface part 213 and second lower surface part 223 This is because overlapping areas occur, and the height (in the Z-axis direction) of these overlapping areas is relatively high, which can cause a height (Z-axis direction) deviation.

[0057] Here, the lengths (in the Y-axis direction) of the first upper portion 212, the second upper portion 222, the first lower portion 213, and the second lower portion 223 can be formed to be half the length (in the Y-axis direction) of the electrode assembly 100. This has the advantage that, since the first cover separation membrane 210 and the second cover separation membrane 220 are formed in the same shape, the first cover separation membrane 210 and the second cover separation membrane 220 can be assembled to the electrode assembly 100 without distinction, making assembly easy.

[0058] Next, the pouch case 300 may include an upper case 310, a lower case 320, and, if necessary, a connecting part to connect them.

[0059] The upper case 310 may consist of a substantially hexahedral cup portion and an extension portion located outside the cup portion, so as to house a part of the electrode assembly 100.

[0060] The lower case 320 is positioned facing the upper case 310 described above and may consist of a roughly hexahedral cup portion and an extension portion located outside the cup portion, so as to accommodate a part of the electrode assembly 100.

[0061] Of course, unlike in Figures 2 and 4, the cup portion can also be provided in only one of the upper case 310 or the lower case 320.

[0062] The pouch case 300, which includes the upper case 310 and the lower case 320, forms the cup portion using a laminate sheet consisting of an outer resin layer, a metal layer, and an inner resin layer.

[0063] The outer resin layer is located on the outermost edge of the pouch case 300 and protects the electrode assembly 100 while ensuring heat resistance and chemical resistance. A heat-resistant polymer with excellent tensile strength, moisture resistance, and air resistance can be used for this layer. For example, nylon or polyethylene terephthalate can be used, but is not limited to these.

[0064] The metal layer in contact with the outer resin layer acts as a barrier layer that prevents moisture and various gases from penetrating into the battery from the outside. A preferred material for such a metal layer is a thin aluminum film, which is lightweight yet has excellent moldability.

[0065] Furthermore, since the internal resin layer is in direct contact with the electrode assembly, it must have insulating and electrolytic resistance properties. In addition, for sealing against the outside, it must have sealing properties; that is, the sealing portion where the internal layers are heat-bonded together must have excellent thermal bonding strength.

[0066] The material for such an internal resin layer can be selected from polyolefin resins such as polypropylene, polyethylene, polyethylene acrylic acid, and polybutylene, polyurethane resins, and polyimide resins, which have excellent chemical resistance and good sealing properties, but are not limited to these. Polypropylene is most preferred because it has excellent mechanical properties such as tensile strength, rigidity, surface hardness, and impact strength, as well as excellent chemical resistance.

[0067] The pair of electrode leads 400, consisting of a positive electrode lead and a negative electrode lead, are typically connected to the aforementioned electrode tab bundle 110, more specifically the positive electrode tab bundle and the negative electrode tab bundle, by methods such as welding, and then protrude to the outside of the pouch case 300.

[0068] The insulating film 500 is positioned on the upper and lower surfaces of the electrode leads 400 that overlap with the sealing portion of the heat-sealed pouch case 300, preventing electricity generated in the electrode assembly 100 from flowing to the pouch case 300 via the electrode leads 400, and further maintaining the sealing of the pouch case 300.

[0069] Here, the insulating film 500 is preferably made of a non-conductive material that does not conduct electricity well, and generally, an insulating tape that is relatively thin while easily adhering to the electrode lead 400 can be used.

[0070] Specifically, the insulating film 500 is one or more materials selected from the group consisting of polyimide (PI), polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyvinyl chloride (PVC), high-density polyethylene (HDPE), and epoxy resin, and is heat-fused to the inner resin layer of the pouch case by heat and pressure.

[0071] Furthermore, this disclosure relates to a battery cell manufactured by the battery cell manufacturing method described above, and may be a battery module, battery pack, or device including the battery cell.

[0072] A person with ordinary skill in the art to which this disclosure belongs will be able to make various applications and modifications within the scope of this disclosure based on the foregoing. [Explanation of Symbols]

[0073] 100 electrode assembly

[0074] 110 Electrode Tabs

[0075] 200 Cover separation membrane

[0076] 210 First cover separation membrane

[0077] 211 First side part 211' First Through Hole

[0078] 212 1st top section 213 1st bottom part

[0079] 220 Second cover separation membrane

[0080] 221 Second side part 221' Second Through Hole

[0081] 222 2nd top section

[0082] 223 2nd bottom part

[0083] 300 pouch cases

[0084] 310 Top Case

[0085] 320 Lower Case

[0086] 400 electrode leads

[0087] 500 insulating film

[0088] T Terrace Section

Claims

1. The electrode tab protrudes, and the electrode assembly includes a positive electrode, a separator membrane, and a negative electrode. A pair of cover separation membranes, consisting of a first cover separation membrane and a second cover separation membrane, are positioned to surround the electrode assembly. A pouch case for housing the electrode assembly and the pair of cover separation membranes, An electrode lead is connected to the electrode tab on one end and protrudes to the outside of the pouch case on the other end, A battery cell comprising an insulating film positioned between the pouch case and the electrode leads.

2. The first cover separation membrane includes a first side portion that adheres to one side of the electrode assembly, a first upper portion that adheres to a part of the upper surface of the electrode assembly, and a first lower portion that adheres to a part of the lower surface of the electrode assembly. The battery cell according to claim 1, wherein the second cover separation membrane includes a second side portion that is in close contact with the other side of the electrode assembly, a second upper portion that is in close contact with a part of the upper surface of the electrode assembly, and a second lower portion that is in close contact with a part of the lower surface of the electrode assembly.

3. The first side portion has a first through-hole formed through which the electrode tab provided on one side of the electrode assembly passes. The battery cell according to claim 2, wherein the second side portion has a second through-hole formed through which the electrode tab provided on the other side of the electrode assembly passes.

4. The sum of the lengths of the first upper portion and the second upper portion is the same as the length of the electrode assembly. The battery cell according to claim 2, wherein the sum of the lengths of the first lower portion and the second lower portion is the same as the length of the electrode assembly.

5. The battery cell according to claim 4, wherein the length of each of the first upper portion, the second upper portion, the first lower portion, and the second lower portion is half the length of the electrode assembly.

6. The battery cell according to claim 1, wherein the separator membrane and the cover separator membrane are made of the same material.

7. The battery cell according to claim 2, wherein the portions of the first cover separator membrane and the second cover separator membrane that are in contact with each other are connected.

8. The battery cell according to claim 2, wherein the widths of the first cover separator membrane and the second cover separator membrane are greater than or equal to the width of the electrode assembly.

9. The battery cell according to claim 7, wherein the portions of the first cover separator and the second cover separator that are in contact with each other are connected via an adhesive member.

10. The battery cell according to claim 7, wherein the portions of the first cover separation membrane and the second cover separation membrane that are in contact with each other are connected by a lamination process.

11. A battery module comprising a battery cell according to any one of claims 1 to 10.

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