Battery cell having improved structure and battery module including same

Abstract

The present invention relates to a battery cell having an improved structure and a battery module including same and, specifically, to a battery cell and a battery module including same, the battery cell comprising: an electrode assembly that has an electrode tab protruding therefrom and includes a positive electrode, a separator, and a negative electrode; a pair of cover separators that surround the electrode assembly and include a first cover separator and a second cover separator; a pouch case that accommodates the electrode assembly and the cover separators; an electrode lead, one side of which is connected to the electrode tab and the other side of which protrudes to the outside of the pouch case; and an insulating film located between the pouch case and the electrode lead.

Description

Battery cell with improved structure and battery module including the same

[0001] This application claims the benefit of priority to Korean Patent Application No. 2024-0033077, filed March 8, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a battery cell with an improved structure and a battery module including the same, and more particularly, to a battery cell with an improved structure and a battery module including the same, which is provided with a cover separator that surrounds an electrode assembly to prevent defects caused by height deviations depending on the position of the battery cell.

[0003] Recently, due to the development of alternative energy sources to address air pollution and energy depletion caused by the use of fossil fuels, demand for secondary batteries that can store generated electric energy is increasing.

[0004] Secondary batteries, the energy source for various electronic devices indispensable in modern society, are seeing increased capacity requirements due to the increasing use and complexity of mobile devices and the development of electric vehicles. To meet user demand, small devices are equipped with multiple battery cells. However, automobiles and other devices utilize battery modules, which electrically connect multiple battery cells, or battery packs comprising multiple such modules.

[0005] Meanwhile, in the battery cell manufacturing process, a tape made of PET material or other material is attached to a portion of the electrode assembly to secure the electrode assembly formed by laminating the positive electrode, negative electrode, and separator.

[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, the cell assembly (1) for a secondary battery according to the prior art has electrode plates (10, 20) and a separator (30) laminated, and the separator (30) arranged on the uppermost and lowermost layers is fixed using a plurality of tapes (50).

[0007] Fixation using such tape is attached to wrap around a portion of the upper surface, side surface, and lower surface of the electrode assembly, and is located on a portion of the upper surface and lower surface, causing a height deviation depending on the position of the electrode assembly.

[0008] In addition, the adhesive layer of the tape reacts with the electrolyte, causing problems such as browning of the separator and depletion of the electrolyte, and when the gas generated during use of the battery cell is trapped in the terrace portion inside the pouch case and reaches a critical point, the gas may penetrate between the secondary battery cell assembly (1), causing a problem of separation between the electrode plates (10, 20) and the separator (30).

[0009] (Prior art literature)

[0010] (Patent Document 1) Korean Patent Publication No. 10-1951783

[0011] In order to solve the above problems, the present invention provides a battery cell having an improved structure in which a cover separator covering the electrode assembly is provided to prevent gaps between components of the electrode assembly due to gas generated within the battery cell and to suppress height deviation by location, and a battery module including the same.

[0012] In order to achieve the above object, a battery cell according to the present invention is characterized by including an electrode assembly (100) having a protruding electrode tab (110) and including a positive electrode, a separator, and a negative electrode, a pair of cover separators (200) positioned to surround the electrode assembly (100) and comprising a first cover separator (210) and a second cover separator (220), a pouch case (300) for storing the electrode assembly (100) and the pair of cover separators (200), an electrode lead (400) having one side connected to the electrode tab (110) and the other side protruding outward from the pouch case, and an insulating film (500) positioned between the pouch case (300) and the electrode lead (400).

[0013] In addition, in the battery cell according to the present invention, the first cover separator (210) includes a first side portion (211) that is in close contact with one side of the electrode assembly (100), 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), and the second cover separator (220) includes a second side portion (221) that is in close contact with the other side of the electrode assembly (100), 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).

[0014] In addition, in the battery cell according to the present invention, 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) can pass, 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) can pass.

[0015] In addition, in the battery cell according to the present invention, the sum of the lengths (Y-axis direction) of the first upper surface portion (212) and the second upper surface portion (222) is equal to the length (Y-axis direction) of the electrode assembly (100), and the sum of the lengths (Y-axis direction) of the first lower surface portion (213) and the second lower surface portion (223) is equal to the length (Y-axis direction) of the electrode assembly (100).

[0016] In addition, in the battery cell according to the present invention, the length (Y-axis direction) of each of the first upper surface portion (212), the second upper surface portion (222), the first lower surface portion (213), and the second lower surface portion (223) is characterized in that it is half the length (Y-axis direction) of the electrode assembly (100).

[0017] In addition, in the battery cell according to the present invention, the separator and the cover separator (200) are characterized in that they are made of the same material.

[0018] In addition, in the battery cell according to the present invention, the first cover separator (210) and the second cover separator (220) are characterized in that the parts that come into contact with each other are connected.

[0019] In addition, in the battery cell according to the present invention, the width (X-axis direction) of the first cover separator (210) and the second cover separator (220) is characterized in that it is greater than the width (X-axis direction) of the electrode assembly (100).

[0020] In addition, in the battery cell according to the present invention, it is characterized in that the contacting portions of the first cover separator (210) and the second cover separator (220) are connected through an adhesive member.

[0021] In addition, in the battery cell according to the present invention, it is characterized in that the contacting portions of the first cover separator (210) and the second cover separator (220) are connected through a lamination process.

[0022] Additionally, the present invention may be a battery module including the above-described battery cell.

[0023] As described above, the battery cell and battery module including the same having an improved structure according to the present invention have the advantage that the cover separator can cover the entire upper and lower surfaces of the electrode assembly, thereby suppressing the occurrence of height deviation depending on the location.

[0024] In addition, according to the battery cell and the battery module including the same according to the present invention, there is an advantage in that the cover separator surrounds the side of the electrode assembly having the electrode tabs, thereby preventing gas generated within the battery cell from penetrating into the electrode assembly from the terrace portion.

[0025] Figure 1 is a cross-sectional view showing a cell assembly for a pouch-type secondary battery according to the prior art.

[0026] Figure 2 is an exploded perspective view showing a battery cell according to a preferred embodiment of the present invention.

[0027] Figure 3 is an exploded perspective view showing an electrode assembly in a battery cell according to a preferred embodiment of the present invention.

[0028] Figure 4 is a cross-sectional view showing a battery cell according to a preferred embodiment of the present invention.

[0029] Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail, so that those skilled in the art can easily implement the present invention. However, when describing the operating principles of preferred embodiments of the present invention in detail, if it is determined that a detailed description of related known functions or configurations may unnecessarily obscure the gist of the present invention, such detailed descriptions will be omitted.

[0030] Additionally, the same drawing reference numerals are used for parts with similar functions and actions throughout the drawings. Throughout the specification, when a part is said to be connected to another part, this includes not only direct connections but also indirect connections with other elements intervening. Furthermore, inclusion of a component does not exclude other components unless specifically stated otherwise, but rather implies the inclusion of additional components.

[0031] Hereinafter, a battery cell having an improved structure according to the present invention and a battery module including the same will be described with reference to the attached drawings.

[0032] FIG. 2 is an exploded perspective view showing a battery cell according to a preferred embodiment of the present invention, FIG. 3 is an exploded perspective view showing an electrode assembly in a battery cell according to a preferred embodiment of the present invention, and FIG. 4 is a cross-sectional view showing a battery cell according to a preferred embodiment of the present invention.

[0033] Referring to FIGS. 2 to 4, a battery cell according to a preferred embodiment of the present invention is configured to include an electrode assembly (100), a cover separator (200), a pouch case (300), an electrode lead (400), and an insulating film (500).

[0034] First, the electrode assembly (100) is a structure in which positive and negative electrodes are alternately laminated multiple times with a separator in between, and a pair of electrode leads (400) composed of positive and negative leads are electrically connected to the positive tab and the negative tab and then exposed to the outside of the pouch case (300).

[0035] The positive electrode is manufactured by applying a positive electrode mixture containing a positive electrode active material onto a positive electrode current collector and then drying the mixture. The positive electrode mixture may optionally further include a binder, a conductive agent, a filler, etc., as needed.

[0036] The positive electrode current collector can generally have a thickness of 3 to 500 ㎛. The positive electrode current collector is not particularly limited as long as it has high conductivity and does not cause chemical changes in the battery. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. can be used. In addition, the positive electrode current collector can form fine unevenness on the surface to increase the adhesiveness of the positive electrode active material, and various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric can be used.

[0037] The cathode active material may be a layered compound such as lithium cobalt oxide (LiCoO2), 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 M x Ni-site type lithium nickel oxide represented by O2 (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 by O2 (wherein, M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or Li2Mn3MO8 (wherein, M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which a portion of the Li in the chemical formula is replaced by an alkaline earth metal ion; disulfide compounds; Fe2(MoO4)3, etc., but are not limited thereto.

[0038] The negative electrode is manufactured by applying a negative electrode mixture containing a negative electrode active material onto a negative electrode current collector and then drying the mixture. The negative electrode mixture may include components such as a conductive agent, a binder, and a filler, as needed.

[0039] The negative electrode current collector is generally made with a thickness of 3 to 500 ㎛. The negative electrode current collector is not particularly limited as long as it has high conductivity and does not cause chemical changes in the battery. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, like the positive electrode current collector, the bonding strength of the negative electrode active material can be strengthened by forming fine unevenness on the surface, and it can be used in various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric, etc.

[0040] The separator prevents short circuits between the aforementioned negative and positive electrodes and allows only the movement of lithium ions, and an insulating thin film with high ion permeability and mechanical strength is used. The pore diameter of the separator is generally 0.01 to 10 ㎛, and the thickness is generally 5 to 300 ㎛. The material of the separator is preferably one selected from among polyethylene, polypropylene, a polyethylene / polypropylene double layer, a polyethylene / polypropylene / polyethylene triple layer, a polypropylene / polyethylene / polypropylene triple layer, and organic fiber filter paper, but is not limited thereto.

[0041] Meanwhile, the negative electrode current collector and the positive electrode dust collector are composed of a portion where a slurry mixed with an active material is applied and a non-coated portion where the slurry is not applied. The non-coated portion is formed by cutting or connecting a separate conductive member to the non-coated portion by ultrasonic welding, etc. to form an electrode tab (110), and these electrode tabs (110) are gathered to form a tab bundle.

[0042] The cover separator (200) wraps around the electrode assembly (100) and is configured to include a first cover separator (210) and a second cover separator (220).

[0043] The cover separator (200) may be made of the same material as the separator included in the electrode assembly (100), and the material is preferably one selected from among polyethylene, polypropylene, polyethylene / polypropylene double layer, polyethylene / polypropylene / polyethylene triple layer, polypropylene / polyethylene / polypropylene triple layer, and organic fiber filter paper, but is not limited thereto.

[0044] The first cover separator (210) and the second cover separator (220) can be connected at the contacting portions, and the contacting portions can be connected through an adhesive material or a lamination process. There is no particular limitation on the connection method as long as it does not cause a height (Z-axis direction) deviation according to the position of the electrode assembly (100) covered by the first cover separator (210) and the second cover separator (220).

[0045] The width (X-axis direction) of the first cover separator (210) and the second cover separator (220) may be formed to be greater than or equal to the width (X-axis direction) of the electrode assembly (100). This is because, when the width (X-axis direction) of the first cover separator (210) and the second cover separator (220) is less than the width (X-axis direction) of the electrode assembly (100), a portion not covered by the first cover separator (210) and the second cover separator (220) may occur on the upper or lower surface of the electrode assembly (100), and the portion not covered may have a relatively low height (Z-axis direction), resulting in a height deviation.

[0046] Next, the first cover separator (210) is positioned to surround a portion of one side of the electrode assembly (100), and is configured to include a first side portion (211) that is in close contact with a portion of the side of the electrode assembly (100) from 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).

[0047] Since the first side portion (211) is in close contact with one side of the electrode assembly (100) in which the electrode tab (110) is formed, a first through hole (211′) through which the electrode tab (110) can pass can be formed.

[0048] The first side portion (211) is positioned in close contact with one side of the electrode assembly (100), so that it can be positioned on one side terrace portion (T) inside the battery cell.

[0049] At this time, the first side portion (211) can prevent gases generated by charging and discharging of battery cells from gathering at the terrace portion (T) and from penetrating toward the electrode assembly (100).

[0050] The second cover separator (220) is positioned to surround a portion of the other side of the electrode assembly (100), and is configured to include a second side portion (221) that is in close contact with the other side of the electrode assembly (100) from which the electrode tab (110) protrudes, a second upper surface portion (222) that is in close contact with a portion of the upper surface of the electrode assembly (100), and a second lower surface portion (223) that is in close contact with a portion of the lower surface of the electrode assembly (100).

[0051] Since the second side portion (221) is in close contact with the other side of the electrode assembly (100) in which the electrode tab (110) is formed, a second through hole (221′) through which the electrode tab (110) can pass can be formed.

[0052] The second side portion (221) is positioned in close contact with one side of the electrode assembly (100), so that it can be positioned on the other side terrace portion (T) inside the battery cell.

[0053] At this time, the second side portion (221), similar to the first side portion (211) described above, can prevent gas generated by charging and discharging of battery cells that can be collected on the terrace portion (T) from penetrating toward the electrode assembly (100).

[0054] It is preferable that the sum of the lengths (Y-axis direction) of the first upper surface portion (212) and the second upper surface portion (222) be equal to the length (Y-axis direction) of the electrode assembly (100). This means that if the sum of the lengths (Y-axis direction) of the first upper surface portion (212) and the second upper surface portion (222) is shorter than the length (Y-axis direction) of the electrode assembly (100), a portion not covered by the first upper surface portion (212) and the second upper surface portion (222) may have a relatively low height (Z-axis direction), resulting in a height (Z-axis direction) deviation.

[0055] Also, conversely, if the sum of the lengths (Y-axis direction) of the first upper surface (212) and the second upper surface (222) is longer than the length (Y-axis direction) of the electrode assembly (100), an overlapping portion may occur between the first upper surface (212) and the second upper surface (222), and since the overlapping portion has a relatively high height (Z-axis direction), a height (Z-axis direction) deviation may occur.

[0056] In addition, it is preferable that the sum of the lengths (Y-axis direction) of the first lower surface portion (213) and the second lower surface portion (223) be the same as the length (Y-axis direction) of the electrode assembly (100). This means that if the sum of the lengths (Y-axis direction) of the first lower surface portion (213) and the second lower surface portion (223) is shorter than the length (Y-axis direction) of the electrode assembly (100), a portion not covered by the first lower surface portion (213) and the second lower surface portion (223) may have a relatively low height (Z-axis direction), resulting in a height (Z-axis direction) deviation.

[0057] Also, conversely, if the sum of the lengths (Y-axis direction) of the first upper surface (212) and the second upper surface (222) is longer than the length (Y-axis direction) of the electrode assembly (100), an overlapping portion may occur between the first upper surface (212) and the second upper surface (222), and since the overlapping portion has a relatively high height (Z-axis direction), a height (Z-axis direction) deviation may occur.

[0058] Here, the length (Y-axis direction) of the first upper surface portion (212), the second upper surface portion (222), the first lower surface portion (213), and the second lower surface portion (223) can be formed to a length (Y-axis direction) that corresponds to half the length (Y-axis direction) of the electrode assembly (100), and since the first cover separator (210) and the second cover separator (220) are formed to have the same shape, the first cover separator (210) and the second cover separator (220) can be assembled to the electrode assembly (100) without distinction, which has the advantage of easy assembly.

[0059] Next, the pouch case (300) can be configured to include an upper case (310), a lower case (320), and a connecting portion connecting them as needed.

[0060] The upper case (310) may be configured with a cup portion having a roughly hexahedral shape and an extension portion positioned outside the cup portion so as to accommodate a portion of the electrode assembly (100).

[0061] The lower case (320) is positioned to face the upper case (310) described above, and may be configured with a cup portion having a roughly hexahedral shape and an extension portion positioned outside the cup portion so as to accommodate a portion of the electrode assembly (100).

[0062] Of course, unlike FIGS. 2 and 4, the cup portion may be provided in only one of the upper case (310) and the lower case (320).

[0063] A pouch case (300) including an upper case (310) and a lower case (320) forms a cup portion using a laminate sheet composed of an outer resin layer, a metal layer, an inner resin layer, etc.

[0064] The outer resin layer is located at the outermost part of the pouch case (300), and in order to protect the electrode assembly (100) while ensuring heat resistance and chemical resistance, a heat-resistant polymer with excellent tensile strength, moisture permeability, and air permeability can be used. For example, nylon or polyethylene terephthalate can be used, but is not limited thereto.

[0065] The metal layer in contact with the outer resin layer serves as a barrier layer that prevents moisture or various gases from penetrating from the outside into the battery. A preferred material for this metal layer is a lightweight aluminum film with excellent formability.

[0066] In addition, since the inner resin layer is in direct contact with the electrode assembly, it must have insulation and electrolytic resistance, and in order to seal it from the outside, the sealing portion where the inner layers are thermally bonded must have excellent thermal bonding strength.

[0067] Materials for the internal resin layer may be selected from, but are not limited to, polyolefin resins such as polypropylene, polyethylene, polyethylene acrylic acid, and polybutylene, which have excellent chemical resistance and good sealing properties, polyurethane resins, and polyimide resins. Polypropylene, which has excellent mechanical properties such as tensile strength, rigidity, surface hardness, and impact strength, and excellent chemical resistance, is most preferable.

[0068] A pair of electrode leads (400) consisting of a positive lead and a negative lead are typically connected to the aforementioned bundle of electrode tabs (110), more specifically, a bundle of positive tabs and a bundle of negative tabs, by welding or the like, and then protrude outward from the pouch case (300).

[0069] The insulating film (500) is positioned on the upper and lower surfaces of the electrode lead (400) overlapping the sealing portion of the heat-sealed pouch case (300), and is configured to prevent electricity generated from the electrode assembly (100) from flowing to the pouch case (300) through the electrode lead (400) and further maintain the sealing of the pouch case (300).

[0070] Here, the insulating film (500) is preferably a non-conductive material that does not conduct electricity well, and generally, an insulating tape that is easy to attach to the electrode lead (400) and has a relatively thin thickness can be used.

[0071] Specifically, the insulating film (500) may be one or two 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 thermally bonded to the inner resin layer of the pouch case through heat and pressure.

[0072] In addition, the present invention may be a battery cell manufactured by the above-described battery cell manufacturing method, and may be a battery module, battery pack, or device including the battery cell.

[0073] Anyone with ordinary skill in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

[0074] (Explanation of symbols)

[0075] 100: Electrode assembly

[0076] 110: Electrode tab

[0077] 200: Cover separator

[0078] 210: First cover separator

[0079] 211: First side 211′: First through hole

[0080] 212: First upper surface 213: First lower surface

[0081] 220: Second cover separator

[0082] 221: Second side 221′: Second through hole

[0083] 222: Second upper surface

[0084] 223: Second lower body

[0085] 300: Pouch Case

[0086] 310: Upper case

[0087] 320: Lower case

[0088] 400: Electrode lead

[0089] 500: Insulating film

[0090] T: Terrace

Claims

1. An electrode assembly having a protruding electrode tab and including an anode, a separator, and a cathode; A pair of cover separators positioned to surround the electrode assembly, the cover separators comprising a first cover separator and a second cover separator; A pouch case for storing the electrode assembly and the pair of cover separators; An electrode lead having one end connected to the electrode tab and the other end protruding outside the pouch case; and A battery cell characterized by comprising an insulating film positioned between the pouch case and the electrode lead.

2. In paragraph 1, The first cover separator includes a first side portion that adheres to one side of the electrode assembly, a first upper portion that adheres to a portion of the upper surface of the electrode assembly, and a first lower portion that adheres to a portion of the lower surface of the electrode assembly. A battery cell characterized in that the second cover separator 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 portion of the upper surface of the electrode assembly, and a second lower portion that is in close contact with a portion of the lower surface of the electrode assembly.

3. In paragraph 2, The first side portion is formed with a first through hole through which the electrode tab provided on one side of the electrode assembly can pass, A battery cell characterized in that the second side portion has a second through hole formed therein through which the electrode tab provided on the other side of the electrode assembly can pass.

4. In paragraph 2, The sum of the lengths of the first upper surface and the second upper surface is equal to the length of the electrode assembly, A battery cell characterized in that the sum of the lengths of the first lower surface portion and the second lower surface portion is equal to the length of the electrode assembly.

5. In paragraph 4, A battery cell characterized in that the length of each of the first upper surface, the second upper surface, the first lower surface, and the second lower surface is half the length of the electrode assembly.

6. In paragraph 1, A battery cell characterized in that the separator and the cover separator are made of the same material.

7. In paragraph 2, A battery cell characterized in that the first cover separator and the second cover separator are connected at a portion where they contact each other.

8. In paragraph 2, A battery cell characterized in that the width of the first cover separator and the second cover separator is greater than the width of the electrode assembly.

9. In paragraph 7, A battery cell characterized in that the contacting portions of the first cover separator and the second cover separator are connected through an adhesive member.

10. In paragraph 7, A battery cell characterized in that the contacting portions of the first cover separator and the second cover separator are connected through a lamination process.

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

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