Electrode assembly, and secondary battery, battery pack, and vehicle including the same

Abstract

The present specification relates to an electrode assembly in which a positive electrode, a negative electrode, and a separator provided between the positive electrode and the negative electrode are laminated and wound up, and further includes an adhesive tape attached to an inside of the wound electrode assembly, the adhesive tape including a porous support, and an adhesive layer on the porous support that comes into contact with an electrolyte and absorbs the electrolyte, expands, and forms an ion migration path, and a secondary battery, a battery pack, and a transportation means including the electrode assembly.

Description

[Technical Field]

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2022-0154682, filed with the Korean Intellectual Property Office on November 17, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present specification relates to an electrode assembly in which a positive electrode, a negative electrode, and a separator provided between the positive electrode and the negative electrode are stacked and wound up, and a secondary battery, a battery pack, and a vehicle including the same. [Background technology]

[0003] In the case of cylindrical, prismatic, or pouch-type batteries, a jelly-roll-shaped electrode assembly is manufactured by winding up long electrodes of a predetermined width together with a separator. A cylindrical battery manufactured by inserting such a jelly-roll-type electrode assembly into a battery case undergoes repeated electrode contraction and expansion during charging and discharging. In particular, if a tab is placed in the core of the jelly-roll-type electrode assembly or if a silicon-based active material is added to the negative electrode, the degree of contraction and expansion of the electrode assembly increases, which significantly increases the pressure acting on the core of the electrode assembly.

[0004] Recently, with the increase in low resistance / high capacity designs, jelly roll-type electrode assemblies are increasingly including multiple tabs or containing silicon-based active materials, which increases the possibility of deformation of the electrode assembly located in the core due to contraction / expansion of the electrode assembly. In particular, if the separator located between the negative and positive electrodes is damaged, the negative and positive electrodes may come into direct contact, resulting in an internal short circuit, which can cause heat generation and fire.

[0005] To solve the problems of separator breakage and internal short circuiting caused by deformation of the electrode assembly, it is necessary to develop a technology that can protect the positive electrode and separator in the corresponding area and suppress the occurrence of internal short circuiting. Summary of the Invention [Problem to be solved by the invention]

[0006] The present specification provides an electrode assembly in which a positive electrode, a negative electrode, and a separator provided between the positive electrode and the negative electrode are stacked and wound up, and a secondary battery, a battery pack, and a transportation means including the same. [Means for solving the problem]

[0007] One embodiment of the present specification provides an electrode assembly in which a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode are stacked and wound up, and further includes an adhesive tape attached to the inside of the wound electrode assembly, the adhesive tape including a porous support and an adhesive layer disposed on the porous support, the adhesive layer contacting an electrolyte solution and absorbing the electrolyte solution to swell and form an ion migration path.

[0008] In another embodiment of the present specification, the adhesive tape may be adhered to at least one of the space between the positive electrode and the separator and the space between the negative electrode and the separator.

[0009] In another embodiment of the present specification, the positive electrode and the negative electrode each include a current collector and an active material layer provided on both sides of the current collector, and the adhesive tape may be adhered to at least one of a space between a mandrel-side end of the active material layer of the positive electrode and the separator and a space between a mandrel-side end of the active material layer of the negative electrode and the separator.

[0010] In still another embodiment of the present specification, the positive electrode may include a positive electrode current collector and positive electrode active material layers provided on both sides of the positive electrode current collector, and the adhesive tape may be adhered to cover an end of the positive electrode active material layer and a surface of the positive electrode current collector close to the end of the positive electrode active material layer.

[0011] In another embodiment of the present specification, the positive electrode and the negative electrode each include a current collector and active material layers provided on both sides of the current collector, and at least one of the positive electrode and the negative electrode includes two or more active material layer portions spaced apart in the winding direction of the electrode assembly and having the active material layers provided on the current collector; and a plain portion between the two or more active material layer portions where the active material layers are not provided on the current collector, and the adhesive tape may be attached to cover the plain portion and an end of the active material layer on the plain portion side.

[0012] In still another embodiment of the present specification, the positive electrode and the negative electrode may each include a current collector and an active material layer provided on both sides of the current collector.

[0013] In another embodiment of the present specification, the mandrel-side end of the negative electrode active material layer may be closer to the mandrel-side end of the separator than the mandrel-side end of the positive electrode active material layer in the winding direction of the electrode assembly.

[0014] In still another embodiment of the present specification, the negative electrode may include an active material layer portion in which the active material layer is provided on the current collector; and uncoated portions in which the active material layer is not provided at both ends of the current collector in the winding direction of the electrode assembly, and the adhesive tape may be attached to the uncoated portions on the mandrel side of the negative electrode.

[0015] In another embodiment of the present specification, the adhesive tape may be attached to a plain portion of the mandrel-side end of the positive electrode active material layer facing the mandrel side.

[0016] In still another embodiment of the present specification, the adhesive tape may be provided on the mandrel side of one of both surfaces of the plain portion where the mandrel side end of the positive electrode active material layer faces the mandrel side.

[0017] In another embodiment of the present specification, the negative electrode may have a negative electrode tab formed on the mandrel-side end of the negative electrode current collector.

[0018] In still another embodiment of the present specification, the pressure-sensitive adhesive layer may contain an acrylate-based pressure-sensitive adhesive having an ethylene oxide side chain.

[0019] Another embodiment of the present specification provides a secondary battery including the above-described electrode assembly and a battery case for accommodating the electrode assembly.

[0020] In still another embodiment of the present specification, the electrode assembly may have a circular cross section perpendicular to the mandrel axis, and the battery case may be cylindrical.

[0021] Another embodiment of the present disclosure provides a battery pack including two or more of the secondary batteries described above.

[0022] Another embodiment of the present disclosure provides a vehicle including the battery pack described above. The vehicle may be any vehicle used to move or transport cargo, people, etc., and may be a bicycle, heavy equipment, agricultural equipment, a car, a bus, an airplane, etc. [Effects of the Invention]

[0023] The electrode assembly according to an embodiment of the present disclosure includes an adhesive tape, which prevents damage to the separator due to deformation of the electrode assembly caused by contraction / expansion of the electrodes during charging / discharging of the battery, and prevents internal short circuits between the electrodes, thereby improving the stability and life characteristics of the battery.

[0024] The electrode assembly according to one embodiment of the present disclosure has the advantage that it does not reduce the capacity of the battery or has little capacity loss because it includes an adhesive tape that allows ion migration and the attachment of the tape does not hinder ion migration. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a view showing a state in which an adhesive tape according to embodiment 1-1 of the present specification is attached. [Figure 2]1 is a view showing a state in which an adhesive tape according to a first and second embodiment of the present specification is attached. [Figure 3] 2 is a view showing a state in which an adhesive tape according to embodiment 2-1 of the present specification is attached. [Figure 4] 2 is a view showing a state in which an adhesive tape according to embodiment 2-2 of the present specification is attached. [Figure 5] 10 is a view showing a state in which an adhesive tape according to a third embodiment of the present specification is attached. [Figure 6] 4 is a view showing a state in which an adhesive tape according to embodiment 4-1 of the present specification is attached. [Figure 7] 4 is a view showing a state in which an adhesive tape according to embodiment 4-2 of the present specification is attached. [Figure 8] FIG. 1(a) is a diagram showing an example of a cross section of an adhesive tape according to one embodiment of the present specification, and FIG. 1(b) is a diagram showing an example of a cross section of an adhesive tape according to another embodiment of the present specification. [Figure 9] 4 shows a winding process of an electrode stack. [Figure 10] FIG. 2 is a perspective view of a wound electrode stack. [Figure 11] FIG. 2 is a vertical cross-sectional view of a secondary battery housed in a battery case that houses a wound electrode stack. [Figure 12] 1 is a diagram illustrating a schematic configuration of a battery pack according to an embodiment of the present invention. [Figure 13] 13 is a diagram illustrating an automobile V including the battery pack 200 of FIG. 12. [Figure 14] CT images of the mandrel portion of the secondary battery after charging and discharging were compared between an example with and without the adhesive tape according to this embodiment and a comparative example. [Figure 15] 1 is a view showing a state in which the adhesive tape according to the first to third embodiments of the present specification is attached. [Figure 16] 10 is a photograph showing the presence or absence of lithium metal deposition after disassembling a battery of an example that had been charged and discharged 50 times. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention will be described in detail below with reference to the drawings. However, the drawings are for illustrative purposes only and the scope of the present invention is not limited by the drawings.

[0027] FIG. 9 shows the winding process of the electrode assembly 1, and FIG. 10 is a perspective view of the wound electrode stack.

[0028] First, the positive electrode 2, the negative electrode 5, and the separator 4 provided between the positive electrode 2 and the negative electrode 5 can be laminated.

[0029] The separator may include two separators, and as shown in FIG. 9, a first separator 4a may be provided between the negative electrode 5 and the positive electrode 2, and an additional second separator 4b may be provided on the surface of the positive electrode 2 opposite to the surface in contact with the first separator 4a. Specifically, the second separator 4b, the positive electrode 2, the first separator 4a, and the negative electrode 5 may be sequentially stacked.

[0030] In the winding direction, the second separator 4b, the positive electrode 2, the first separator 4a, and the negative electrode 5 may be stacked in this order and wound on the negative electrode 5 side, as shown in Fig. 9. When wound in this manner, the separator may be exposed at the outermost edge 1b of the wound electrode assembly.

[0031] If necessary, the electrode assembly may be wound in the opposite direction to the direction illustrated in Fig. 9. When wound in this manner, the negative electrode 5 or the negative electrode 5 and the separator 4 together may be exposed at the outermost case 1b of the wound electrode assembly. In this case, when the negative electrode is exposed at the outermost case 1b, only the outer-case-side negative electrode uncoated portion, which does not have a negative electrode active material layer, may be exposed, or both the outer-case-side negative electrode uncoated portion and the outer-case-side negative electrode active material layer portion may be exposed at the outermost case 1b.

[0032] The electrode assembly 1 wound up as shown in FIG. 10 includes an adhesive tape 10 adhered to the inside 1c of the electrode assembly 1.

[0033] In this specification, the "inner part 1c" where the adhesive tape is adhered refers to the part of the wound electrode assembly excluding the outermost part 1b. In this case, if the wound electrode assembly is a pillar, the outermost part 1b refers to the side surface exposed to the outside, and the "inner part 1c" where the adhesive tape is adhered includes the entire inner region of the pillar excluding the side surface.

[0034] The positive electrode 2 and the negative electrode 5 may each include a current collector and an active material layer provided on at least one surface of the current collector.

[0035] The positive electrode 2 may include a positive electrode current collector 2a and a positive electrode active material layer 2b provided on at least one surface of the positive electrode current collector 2a. The positive electrode active material layer 2b may be provided on both surfaces of the positive electrode current collector 2a, or may include a first positive electrode active material layer 2b' provided on one surface of the positive electrode current collector 2a and a second positive electrode active material layer 2b'' provided on the surface opposite to the surface on which the first positive electrode active material layer 2b' is provided.

[0036] The positive electrode 2 includes one or more positive electrode tabs 2c, and the positive electrode tabs 2c are located in positive electrode uncoated portions 2e where the positive electrode active material layer 2b is not provided.

[0037] In one embodiment, the positive electrode 2 may include a positive electrode active material layer portion 2d in which a positive electrode active material layer is provided on the positive electrode current collector 2a, and a positive electrode uncoated portion 2e in which no positive electrode active material layer is provided at one or both end portions of the positive electrode current collector 2a. In this case, the positive electrode tab 2c may be located in the positive electrode uncoated portion 2e located at one or both end portions of the positive electrode current collector 2a, preferably in the positive electrode uncoated portion 2e at one end portion.

[0038] In another embodiment, the positive electrode 2 may include a positive electrode uncoated portion 2e at an outer edge of the positive electrode current collector 2a where no positive electrode active material layer is provided, and a positive electrode tab 2c may be formed on the positive electrode uncoated portion 2e.

[0039] In another embodiment, the positive electrode 2 may include two or more positive electrode active material layer portions 2d on the positive electrode current collector 2a, spaced apart in the longitudinal direction and including positive electrode active material layers, and a positive electrode uncoated portion 2e between the two or more positive electrode active material layer portions 2d, where no positive electrode active material layer is provided. In this case, the positive electrode tab 2c may be positioned in the positive electrode uncoated portion 2e between the two or more positive electrode active material layer portions 2d, preferably in the positive electrode uncoated portion 2e between two positive electrode active material layer portions 2d. In this case, both end portions of the positive electrode 2 may be formed as free edges without a positive electrode uncoated portion.

[0040] The positive electrode 2 may include a positive electrode current collector 2a and positive electrode active material layers 2b provided on both sides of the positive electrode current collector 2a. A first positive electrode active material layer 2b' provided on one side of the positive electrode current collector 2a and a second positive electrode active material layer 2b'' provided on the other side may have the same or different lengths.

[0041] The negative electrode 5 may include a negative electrode current collector 5a and a negative electrode active material layer 5b provided on at least one surface of the negative electrode current collector 5a. The negative electrode active material layer 5b may be provided on both surfaces of the negative electrode current collector 5a, or may include a first negative electrode active material layer 5b' provided on one surface of the negative electrode current collector 5a and a second negative electrode active material layer 5b'' provided on the surface opposite to the surface on which the first negative electrode active material layer 5b' is provided.

[0042] The negative electrode 5 includes one or more negative electrode tabs 5c, and the negative electrode tabs 5c are located in negative electrode uncoated portions where the negative electrode active material layer 5b is not provided.

[0043] In one embodiment, the negative electrode 5 may include a negative electrode active material layer portion in which a negative electrode active material layer is provided on the negative electrode current collector 5a, and a negative electrode uncoated portion in which no negative electrode active material layer is provided at one or both end portions of the negative electrode current collector 5a. In this case, the negative electrode tabs 5c may be located in the negative electrode uncoated portions located at one or both end portions of the negative electrode current collector 5a, preferably in the negative electrode uncoated portions at both end portions.

[0044] In another embodiment, the negative electrode 5 may include a negative electrode uncoated portion on which the active material layer is not provided at the mandrel-side end of the negative electrode current collector 5a, and a negative electrode tab 5c may be formed on the negative electrode uncoated portion.

[0045] The negative electrode 5 may include a negative electrode current collector 5a and negative electrode active material layers 5b provided on both sides of the negative electrode current collector 5a. A first negative electrode active material layer 5b' provided on one side of the negative electrode current collector 5a and a second negative electrode active material layer 5b'' provided on the other side may have the same or different lengths.

[0046] In yet another embodiment, the positive electrode 2 may include two positive electrode active material layer portions 2d′, 2d″ spaced apart in the winding direction of the electrode assembly 1, in which the positive electrode active material layer 2b is provided on the positive electrode current collector 2a; and a positive electrode uncoated portion 2e between the two active material layer portions where the positive electrode active material layer is not provided on the positive electrode current collector 2a, and one positive electrode tab 2c is formed on the positive electrode uncoated portion 2e. The negative electrode 5 may include two negative electrode uncoated portions on both side ends of the negative electrode current collector 5a, each of which is not provided with the negative electrode active material layer, and one negative electrode tab 5c is formed on each of the two negative electrode uncoated portions.

[0047] The electrode assembly 1 shown in Figures 1 to 7 is in a stacked state before being wound, and may be wound in a winding direction A or a winding direction B. The arrangement of the outermost exposed portion of the wound electrode assembly varies depending on the winding direction and the length of each stack.

[0048] In the first embodiment, the adhesive tape 10 may be adhered to at least one of the spaces between the positive electrode 2 and the separator 4 and the spaces between the negative electrode 5 and the separator 4. The positive electrode 2 and the negative electrode 5 each include a current collector and an active material layer provided on at least one surface of the current collector, and the adhesive tape 10 may be adhered to at least one of the spaces between an end of the positive electrode active material layer 2b and the separator 4 and the spaces between an end of the negative electrode active material layer 5b and the separator 4.

[0049] FIG. 1 is a view showing an attached state of an adhesive tape according to embodiment 1-1 of the present specification. In embodiment 1-1, the adhesive tape 10 may be adhered between the negative electrode 5 and the separator 4. The negative electrode 5 includes a negative electrode current collector 5a and a negative electrode active material layer 5b provided on at least one surface of the negative electrode current collector 5a. The adhesive tape 10 may be adhered between an end of the negative electrode active material layer 5b and the separator 4, preferably between an end of the negative electrode active material layer 5b facing the mandrel 1a and the separator 4. In this case, the end of the negative electrode active material layer 5b facing the mandrel 1a refers to the portion where winding begins in the winding direction A or B in FIG. 1, because this portion is located on the mandrel 1a side of the wound electrode assembly.

[0050] FIG. 2 is a diagram showing an attached state of an adhesive tape according to embodiment 1-2 of the present specification. In embodiment 1-2, the adhesive tape 10 may be adhered between the positive electrode 2 and the separator 4. The positive electrode 2 includes a positive electrode current collector 2a and a positive electrode active material layer 2b provided on at least one surface of the positive electrode current collector 2a. The adhesive tape 10 may be adhered between an end of the positive electrode active material layer 2b and the separator 4, preferably between an end of the positive electrode active material layer 2b on the mandrel 1a side and the separator 4. In this case, the mandrel 1a side end of the positive electrode active material layer 2b refers to the portion where winding begins in the winding direction A or B in FIG. 2, because this portion is located on the mandrel 1a side in the wound electrode assembly.

[0051] In the second embodiment, the positive electrode 2 includes a positive electrode current collector 2a and a positive electrode active material layer 2b provided on at least one surface of the positive electrode current collector 2a, and the adhesive tape 10 may be adhered to cover an end of the positive electrode active material layer 2b and a surface of the positive electrode current collector 2a close to the end of the positive electrode active material layer 2b.

[0052] FIG. 3 is a diagram showing an attached state of an adhesive tape 10 according to embodiment 2-1 of the present specification. In embodiment 2-1, the positive electrode 2 includes a positive electrode current collector 2a and positive electrode active material layers 2b provided on both sides of the positive electrode current collector 2a. The adhesive tape 10 may be adhered to cover an end of the positive electrode active material layer 2b and a surface of the positive electrode current collector 2a adjacent to the end of the positive electrode active material layer 2b. In this case, a positive electrode tab may be provided in at least one location of a positive electrode uncoated portion 2e that does not include the positive electrode active material layer 2b, but this is not shown as a limitation. The adhesive tape 10 may also be adhered to both sides of the positive electrode current collector 2a.

[0053] 4 is a diagram showing an attached state of an adhesive tape according to embodiment 2-2 of the present specification. In embodiment 2-2, the positive electrode 2 includes a positive electrode current collector 2a, positive electrode active material layers 2b provided on both sides of the positive electrode current collector 2a, and positive electrode tabs 2c provided in positive electrode uncoated portions 2e on the positive electrode current collector 2a where the positive electrode active material layers 2b are not provided. The adhesive tape 10 is adhered to cover ends of the positive electrode active material layers 2b and the surface of the positive electrode current collector 2a adjacent to the ends of the positive electrode active material layers 2b. The adhesive tape 10 may also be adhered to the positive electrode uncoated portions 2e on which the positive electrode tabs 2c are provided.

[0054] In the positive electrode uncoated portion 2e where the positive electrode tab 2c is provided, the adhesive tape 10 may be adhered to extend from the end of the positive electrode active material layer 2b to the positive electrode tab 2c. In this case, the adhesive tape 10 may be adhered to both sides of the positive electrode current collector 2a.

[0055] In one embodiment, the positive electrode 2 and the negative electrode 5 each include a current collector and an active material layer provided on at least one surface of the current collector, and at least one of the positive electrode 2 and the negative electrode 5 includes two or more active material layer portions spaced apart in the winding direction of the electrode assembly and in which the active material layer is provided on the current collector; and a plain portion between the two or more active material layer portions in which the active material layer is not provided on the current collector, and the adhesive tape 10 may be adhered to cover the plain portion and an end of the active material layer on the plain portion side.

[0056] 5 is a view showing an attached state of an adhesive tape according to a third embodiment of the present specification. In the third embodiment, the positive electrode 2 includes a positive electrode current collector 2a and positive electrode active material layers 2b provided on both sides of the positive electrode current collector 2a. The positive electrode 2 includes two positive electrode active material layer portions 2d', 2d'' spaced apart in the winding direction of the electrode assembly 1, where the positive electrode active material layer 2b is provided on the positive electrode current collector 2a; and a positive electrode uncoated portion 2e between the two positive electrode active material layer portions where the positive electrode active material layer 2b is not provided on the positive electrode current collector 2a. The adhesive tape 10 may be adhered to cover the positive electrode uncoated portion 2e and an end of the positive electrode active material layer 2b on the positive electrode uncoated portion 2e side.

[0057] In the fourth embodiment, the positive electrode 2 and the negative electrode 5 may each include a current collector and active material layers provided on both sides of the current collector. The first active material layer provided on one side of the current collector and the second active material layer provided on the other side may have the same or different lengths. In the winding direction of the electrode assembly 1, the mandrel 1a side end of the separator 4 may be closer to the mandrel 1a side end of the negative electrode active material layer 5b than the mandrel 1a side end of the positive electrode active material layer 2b.

[0058] The negative electrode 5 includes a negative electrode active material layer portion in which a negative electrode active material layer 5b is provided on a negative electrode current collector 5a; and negative electrode uncoated portions in which the negative electrode active material layer 5b is not provided on both ends of the negative electrode current collector 5a in the winding direction of the electrode assembly 1, and the adhesive tape 10 may be adhered to the negative electrode uncoated portions on the mandrel 1a side.

[0059] In the fourth embodiment, the adhesive tape 10 may be adhered to the negative electrode uncoated portion where the mandrel 1a side end of the positive electrode active material layer 2b faces the mandrel 1a side.

[0060] In the fourth embodiment, the adhesive tape 10 may be provided on the mandrel 1a side of the negative electrode uncoated portion on both sides where the mandrel 1a side end of the positive electrode active material layer 2b faces the mandrel 1a side.

[0061] Fig. 6 is a view showing an attached state of an adhesive tape 10 according to embodiment 4-1 of the present specification, and Fig. 7 is a view showing an attached state of an adhesive tape 10 according to embodiment 4-2 of the present specification. The adhesive tape 10 according to embodiment 4-2 differs from the adhesive tape 10 according to embodiment 4-1 in that the adhesive tape extends to and covers the negative electrode tab 5c.

[0062] In embodiments 4-1 and 4-2, the end of the first negative electrode active material layer 5b' provided on one surface of the negative electrode current collector 5a, which is adjacent to the mandrel 1a, may be shorter than the end of the second negative electrode active material layer 5b'' provided on the other surface, which is adjacent to the mandrel 1a, and a negative electrode tab 5c may be provided at the end of the surface of the negative electrode current collector 5a on which the first negative electrode active material layer 5b' is provided. In this case, the adhesive tape 10 may be adhered to the negative electrode uncoated portion on the mandrel 1a side.

[0063] In the 4-1 and 4-2 embodiments, the adhesive tape 10 may be adhered to the negative electrode uncoated portion that faces the mandrel 1a side end of the positive electrode active material layer 2b with respect to the first separator 4a on the mandrel 1a side.

[0064] In the fourth embodiment, the adhesive tape 10 may be provided on the surface of the negative electrode current collector 5a on which the first negative electrode active material layer 5b′ is provided, among both surfaces of the negative electrode uncoated portion that face the mandrel 1a side end of the positive electrode active material layer 2b with respect to the first separator 4a on the mandrel 1a side.

[0065] The adhesive tape 10 includes a porous support 12 and an adhesive layer 11 provided on the porous support 12 .

[0066] Fig. 8 is a diagram illustrating an example of a cross section of an adhesive tape 10. The adhesive layer 11 may be provided on at least one surface of a porous support 12, and may be provided on the entire surface of the porous support 12 as shown in Fig. 8(a), or may be a patterned layer provided on one surface of the porous support 12 as shown in Fig. 8(b).

[0067] The adhesive layer 11 being provided as a patterned layer means that the adhesive layer 11 may be provided at intervals rather than being applied to the entire surface of the porous support 12. Specifically, this means that the adhesive layer 11 is divided into areas where the adhesive is not applied and areas where the adhesive is applied. In this case, the adhesive layer may be provided in a regular pattern by repeating the areas where the adhesive is not applied and the areas where the adhesive is applied. For example, the adhesive may be provided in a pattern such as stripes, dots, waves, or a checkered pattern on at least one surface of the porous support 12.

[0068] The porous support 12 may be made of, for example, one or more films selected from the group consisting of an acrylic film, a polyolefin film, a polyamide film, a polycarbonate film, a polyurethane film, a cellulose acetate film, and a polyester film, but is not limited thereto.

[0069] When a polyester film is used as the porous support 12, one or more films selected from the group consisting of polyethylene terephthalate film, polyethylene naphthalate film, and polybutylene terephthalate film may be used. When a cellulose-based porous support 12 is used as the porous support 12, for example, a porous support 12 containing a cellulose acetate resin or a cellulose alkylate resin may be used, which is manufactured by subjecting a mixture containing the resin to an extrusion or casting process. Examples of the cellulose alkylate include cellulose acetate propionate and cellulose acetate butylate.

[0070] The method for manufacturing the porous support 12 using the resin is not particularly limited, and for example, a conventional film or sheet forming method such as extrusion or casting of raw materials containing the resin and, if necessary, known additives may be used.

[0071] When the porous support 12 is in the form of a sheet or film, the thickness of the porous support 12 is not particularly limited and may be, for example, about 10 to 200 μm, 10 to 100 μm, 10 to 50 μm, 15 to 30 μm, or 15 to 20 μm.

[0072] The adhesive tape 10 includes an adhesive layer 11, which absorbs the electrolyte solution and expands upon contact with the electrolyte, thereby forming an ion migration path in the adhesive tape 10. For example, the adhesive layer 11 may expand in the thickness direction and / or length direction upon contact with the electrolyte, thereby forming a three-dimensional structure. The "three-dimensional structure" of the adhesive tape 10 is formed through the interaction of the expansion force of the adhesive layer 11 of the adhesive tape 10 upon contact with the electrolyte and the peel force from the porous support 12, and may be a concept that includes any structure that allows the adhesive layer 11 to be detached from the electrode assembly.

[0073] In one example, the three-dimensional structure may include a plurality of protruding shapes in a direction that is not parallel to the length direction of the pressure-sensitive adhesive layer, preferably perpendicular to the length direction. In the above, the "length direction" may refer to a direction perpendicular to the thickness direction of the pressure-sensitive adhesive layer when the pressure-sensitive adhesive layer is held flat. Furthermore, the "vertical" or "horizontal" means substantially vertical or horizontal within a range that does not impair the intended effect, and may include an error of, for example, ±10 degrees, ±5 degrees, or ±3 degrees.

[0074] As described above, the centerline average roughness Ra of the surface of the pressure-sensitive adhesive layer that forms a three-dimensional structure including a plurality of protruding shapes after contact with the electrolyte may be 100 to 250 μm, for example, 150 to 240 μm or 155 to 230 μm. The centerline average roughness Ra may be a value measured 24 hours after contact with the electrolyte. When the centerline average roughness Ra of the three-dimensional structure formed by the pressure-sensitive adhesive layer of the present application is adjusted within the above range, the pressure-sensitive adhesive tape can be efficiently detached from the attachment surface of the inner part 1c of the electrode assembly. The "centerline average roughness" refers to the value in micrometers calculated from the following equation (1), for example, by photographing a cross section of the pressure-sensitive adhesive layer that forms a three-dimensional structure, mathematically remodeling the cross section of the three-dimensional structure using the photograph to obtain a roughness curve, and then extracting a reference length L from the roughness curve in the mean line direction. The mean line direction is the x-axis and the height direction is the y-axis, and the roughness curve is expressed as y = f(x).

[0075]

number

[0076] The centerline average roughness is measured according to the standard of ASTM D4417, or is determined according to the definition in JIS B0031 or JIS B0601.

[0077] By providing adhesive tape that can form an ion migration path through such a change in three-dimensional structure, the tape attachment does not hinder ion migration, so the battery capacity is not reduced or capacity loss is small.

[0078] In one example, the adhesive layer 11 may include a cured product of an adhesive composition or a crosslinked polymer contained in the adhesive composition. For example, the adhesive composition includes a polymer having polymerization units derived from a (meth)acrylic acid ester monomer, a monomer having a polar functional group, and a crosslinkable monomer having a crosslinkable functional group. In one example, in a secondary battery manufactured by attaching an adhesive tape including an adhesive layer formed from the adhesive composition to an electrode assembly via the adhesive layer and inserting the electrode assembly into a battery can, the adhesive layer deforms, for example, swells or expands when it comes into contact with an electrolyte injected into the secondary battery, due to the presence of the polar functional group of the monomer having the polar functional group present in the adhesive layer. In this case, the adhesive tape forms an ion migration path, and the surface of the adhesive layer has a surface roughness value within a specific range, which reduces the adhesive strength or peel strength between the electrode assembly and the adhesive layer, and the adhesive layer is detached from the electrode assembly, thereby inducing isotropic volumetric expansion and contraction of the electrode assembly. Since the tape attachment does not interfere with ion migration, there is an advantage in that the battery capacity is not reduced or capacity loss is small.

[0079] The pressure-sensitive adhesive composition includes a polymer having a polymerization unit, and in one example, the polymer may include, for example, a (meth)acrylic acid ester monomer, a monomer having a polar functional group, and a crosslinkable monomer having a crosslinkable functional group, in a polymerized form.

[0080] The (meth)acrylic acid ester monomer contained in the polymerized units of the polymer may be, for example, an alkyl(meth)acrylate, or, taking into consideration the cohesive strength, glass transition temperature, or adhesiveness of the adhesive, an alkyl(meth)acrylate having an alkyl group of 1 to 14 carbon atoms. Examples of such a monomer may include, but are not limited to, one or more of methyl(meth)acrylate, ethyl(meth)acrylate, n-propyl(meth)acrylate, isopropyl(meth)acrylate, n-butyl(meth)acrylate, t-butyl(meth)acrylate, sec-butyl(meth)acrylate, pentyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, 2-ethylbutyl(meth)acrylate, n-octyl(meth)acrylate, isooctyl(meth)acrylate, isononyl(meth)acrylate, lauryl(meth)acrylate, and tetradecyl(meth)acrylate.

[0081] In the above, "(meth)acrylate" means acrylate or methacrylate, and the same applies to other terms using "(meth)".

[0082] The monomer having a polar functional group is a monomer with excellent affinity for electrolytes, and is included as a polymerization unit in the polymer of the adhesive composition so that when an adhesive layer manufactured using the adhesive composition comes into contact with an electrolyte, it deforms, e.g., swells, thereby reducing the adhesive strength or peel strength between the electrode assembly and the adhesive layer. Furthermore, in the present application, by using a monomer having a specific structure as the monomer having a polar functional group, the adhesive tape can form a three-dimensional structure with a specific surface roughness when contacted with an electrolyte. This allows the adhesive tape to be detached from the electrode assembly with excellent efficiency, thereby inducing isotropic volumetric expansion and contraction of the electrode assembly and not interfering with ion migration due to tape attachment, resulting in no reduction or minimal capacity loss of the battery.

[0083] In one example, the monomer having a polar functional group can be represented by the following Chemical Formula 1:

[0084] [ka]

[0085] In the above formula 1, R1 represents hydrogen or an alkyl group having 1 to 12 carbon atoms; R2 represents an alkylene group having 1 to 6 carbon atoms; R3 represents hydrogen, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 24 carbon atoms, or an arylalkyl group having 6 to 48 carbon atoms; n is 0 or greater.

[0086] In Chemical Formula 1, R1 is hydrogen or an alkyl group having 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, and examples thereof include hydrogen, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. Preferably, R1 is hydrogen or a methyl group, but is not limited thereto.

[0087] In addition, in the above Chemical Formula 1, R2 is an alkylene group having 1 to 6, 1 to 4, or 1 to 2 carbon atoms, and may be, for example, ethylene or propylene, but is not limited thereto.

[0088] R3 represents hydrogen; an alkyl group having 1 to 12, 1 to 8, 1 to 6, or 1 to 4 carbon atoms; an aryl group having 6 to 24, 6 to 20, 6 to 18, or 6 to 12 carbon atoms; or an arylalkyl group having 6 to 48, 6 to 30, 6 to 24, or 6 to 18 carbon atoms, and examples thereof include hydrogen, a methyl group, an ethyl group, a propyl group, a phenyl group, a naphthalene group, a butylphenol group, a pentylphenol group, a hexylphenol group, a heptylphenol group, an octylphenol group, and a nonylphenol group, but are not limited to these.

[0089] Furthermore, the n may be 0 or more, for example, 1 or more, preferably 2 or more.

[0090] In one example, the monomer represented by Formula 1 may be a monomer represented by Formula 2 below.

[0091] [ka]

[0092] In the above Chemical Formula 2, R1 and R3 are as defined above; p+q is greater than or equal to 1, p is an integer from 0 to 100, and q is an integer from 0 to 100.

[0093] Examples of the monomer represented by Chemical Formula 1 or Chemical Formula 2 include methoxyethyl (meth)acrylate, methoxyethoxyethyl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, ethoxytriethylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, polyethylene glycol methyl ether (meth)acrylate, ethoxylated acrylic nonylphenol (meth)acrylate, propoxylated acrylic nonylphenol (meth)acrylate, ethoxylated acrylic phenol (meth)acrylate, and polypropylene glycol (meth)acrylate. Preferred examples include, but are not limited to, methoxyethyl (meth)acrylate, methoxyethoxyethyl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, ethoxytriethylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, and polyethylene glycol methyl ether (meth)acrylate.

[0094] The monomer represented by Formula 1 or 2 contains at least one oxygen atom, and the high electronegativity of the oxygen atom makes the monomer highly polar. Therefore, an adhesive layer containing the monomer has high affinity with a polar electrolyte solution and can swell upon contact with the electrolyte. Meanwhile, the term "electrolyte solution" in the above description may refer to an ion-conducting medium used in, for example, a secondary battery. In one example, the electrolyte may be an electrolytic solution, which is a liquid medium, but is not limited thereto. In this specification, the electrolytic solution may also be referred to as "electrolyte."

[0095] The polymer may contain, but is not limited to, 30 to 300 parts by weight, for example, 40 to 280 parts by weight or 44 to 250 parts by weight, of the monomer represented by Chemical Formula 1 relative to 100 parts by weight of the (meth)acrylic acid ester monomer. The monomer represented by Chemical Formula 1 may be contained in an amount of 25 to 80 parts by weight, for example, 25 to 75 parts by weight or 30 to 70 parts by weight, relative to 100 parts by weight of the total monomers contained as polymerized units in the polymer. If the amount of the monomer represented by Chemical Formula 1 is too small, the adhesive layer may not expand sufficiently to be detached from the electrode assembly upon contact with the electrolyte. If the amount of the monomer represented by Chemical Formula 1 is too large, excessive gelation may occur during the polymerization reaction of the polymer, making it difficult to achieve adhesive properties. Therefore, the content of the monomer having a polar functional group may be adjusted within the above range in consideration of these factors. In this specification, unless otherwise specified, "parts by weight" means relative "weight ratio".

[0096] The crosslinkable monomer having a crosslinkable functional group may be copolymerized with the (meth)acrylic acid ester monomer or other monomers contained in the polymer, and after copolymerization, may provide a crosslinking point in the main chain of the polymer that can react with a multifunctional crosslinking agent. The crosslinkable functional group may be a hydroxyl group, a carboxyl group, an isocyanate group, a glycidyl group, an amide group, or the like, and in some cases may be a photocrosslinkable functional group such as an acryloyl group or a methacryloyl group. The photocrosslinkable functional group may be introduced by reacting a compound having a photocrosslinkable functional group with the crosslinkable functional group provided by the copolymerizable monomer. Examples of the crosslinkable monomer containing a hydroxy group include, but are not limited to, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxyethylene glycol (meth)acrylate, glycerol (meth)acrylate, and hydroxypropylene glycol (meth)acrylate, or a mixture of at least one of these monomers. Examples of the carboxyl group-containing monomer include, but are not limited to, (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. In addition, the crosslinkable monomer containing a glycidyl group may be, for example, glycidyl (meth)acrylate, epoxy alkyl (meth)acrylate, or epoxy cycloalkyl alkyl (meth)acrylate such as epoxy cyclohexyl methyl (meth)acrylate, but is not limited thereto.Examples of the crosslinkable monomer containing an isocyanate group that may be used include, but are not limited to, 2-isocyanate ethyl (meth)acrylate, 1,1-bis(acryloyloxymethyl)ethyl isocyanate, (meth)acryloyloxyethyl isocyanate, meta-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl diisocyanate, or allyl isocyanate; an acryloyl monoisocyanate compound obtained by reacting a diisocyanate compound or a polyisocyanate compound with 2-hydroxyethyl (meth)acrylate; or an acryloyl monoisocyanate compound obtained by reacting a diisocyanate compound or a polyisocyanate compound with a polyol compound and 2-hydroxyethyl (meth)acrylate. Examples of the amide group-containing monomer include, but are not limited to, (meth)acrylamide, diethylacrylamide, N-vinylpyrrolidone, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N'-methylenebisacrylamide, N,N-dimethylaminopropylacrylamide, N,N-dimethylaminopropylmethacrylamide, and diacetone(meth)acrylamide. Examples of the amino group-containing monomer include, but are not limited to, aminoethyl(meth)acrylate, N,N-dimethylaminoethyl(meth)acrylate, and N,N-dimethylaminopropyl(meth)acrylate. Examples of the alkoxysilyl group-containing monomer include, but are not limited to, trimethoxysilylpropyl(meth)acrylate and aryloxyethyl(meth)acrylate.

[0097] The polymer may contain, but is not limited to, 0.1 to 10 parts by weight, for example, 2.5 to 10 parts by weight, 2.9 to 9 parts by weight, or 2.9 to 8 parts by weight of a crosslinkable monomer relative to 100 parts by weight of a (meth)acrylic acid ester monomer. The crosslinkable monomer may be contained in an amount of 0.1 to 5 parts by weight, for example, 0.5 to 3 parts by weight, or 1 to 2 parts by weight, relative to 100 parts by weight of the total monomers contained in the polymerized units of the polymer. If the crosslinkable monomer content is too high, the peel strength may be too low, making it difficult for the adhesive layer to secure the electrode assembly. If the crosslinkable monomer content is too low, the adhesive layer may not expand sufficiently to be detached from the electrode assembly upon contact with the electrolyte. Taking these factors into consideration, the content of the crosslinkable monomer may be adjusted within the above range.

[0098] The polymer may further contain other functional comonomers in a polymerized form, if necessary, and examples thereof include the monomers represented by the following Formula 3.

[0099] [ka]

[0100] In the formula, R6 to R8 each independently represent hydrogen or an alkyl group, and R9 represents cyano; alkyl-substituted or unsubstituted phenyl; acetyloxy; or COR 10 In this case, R 10 represents amino unsubstituted or substituted with alkyl or alkoxyalkyl, or glycidyloxy.

[0101] R6 to R 10 In the definitions, alkyl and alkoxy each independently mean alkyl or alkoxy having 1 to 8 carbon atoms, and are preferably methyl, ethyl, methoxy, ethoxy, propoxy or butoxy.

[0102] Specific examples of the monomer of Formula 3 include, but are not limited to, nitrogen-containing monomers such as (meth)acrylamide, N-butoxymethyl(meth)acrylamide, N-methyl(meth)acrylamide, (meth)acrylonitrile, N-vinylpyrrolidone, and N-vinylcaprolactam; styrene-based monomers such as styrene and methylstyrene; glycidyl(meth)acrylate; caprolactone, and vinyl esters of carboxylic acids such as vinyl acetate.

[0103] The polymer may be included in the composition in a crosslinked form using a multifunctional crosslinker. When the polymer is included in a crosslinked form, the adhesive layer prepared from the composition may have the property of expanding or swelling upon contact with an electrolyte, thereby preventing disconnection of the electrode. Furthermore, when the polymer is included in a crosslinked form, the adhesive layer prepared from the adhesive composition may have appropriate cohesive strength.

[0104] The type of polyfunctional crosslinking agent crosslinking the polymer is not particularly limited, and an appropriate crosslinking agent may be selected depending on the type of crosslinkable functional group present in the polymer from known crosslinking agents such as isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, metal chelate crosslinking agents, photocrosslinking agents, etc. In the above, examples of the isocyanate crosslinking agent include diisocyanates such as tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoboron diisocyanate, tetramethylxylene diisocyanate, and naphthalene diisocyanate, as well as reaction products of the diisocyanates with polyols, and in the above, trimethylolpropane or the like may be used as the polyol. Examples of epoxy crosslinking agents that can be used include ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N,N,N',N'-tetraglycidylethylenediamine, and glycerin diglycidyl ether. Examples of aziridine crosslinking agents include N,N'-toluene-2,4-bis(1-aziridinecarboxamide), N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), triethylenemelamine, bisisoprothaloyl-1-(2-methylaziridine), and tri-1-aziridinylphosphine oxide. Examples of metal chelate crosslinking agents include compounds in which a polyvalent metal is coordinated with a compound such as acetylacetone or ethyl acetoacetate. In the above, examples of the polyvalent metal include aluminum, iron, zinc, tin, titanium, antimony, magnesium, and vanadium. Examples of photocrosslinking agents that can be used include polyfunctional acrylates. In the above, one or more crosslinking agents may be used in consideration of the type of crosslinkable functional group contained in the polymer.

[0105] The weight ratio of the multifunctional crosslinker in the pressure-sensitive adhesive composition can be adjusted to a range that ensures, for example, a desired peel strength or gel fraction (described below). For example, the crosslinker may be included in an amount of 0.001 to 10 parts by weight, e.g., 0.1 to 5 parts by weight or 0.5 to 4 parts by weight, per 100 parts by weight of the total composition, but is not limited thereto. If the ratio of the multifunctional crosslinker is too low, the cohesive strength of the pressure-sensitive adhesive layer may not be adequately ensured, and if it is too high, the adhesive properties may be reduced. Therefore, an appropriate range should be selected taking this into consideration.

[0106] The polymer contained in the pressure-sensitive adhesive composition may be prepared by subjecting a mixture of the above-mentioned monomers to a polymerization process such as solution polymerization, photo polymerization, bulk polymerization, suspension polymerization, or emulsion polymerization.

[0107] The polymer may have a weight average molecular weight (Mw) of approximately 300,000 to 2.5 million, 400,000 to 2 million, 400,000 to 1.5 million, 400,000 to 1 million, 500,000 to 2 million, 800,000 to 1.8 million, 600,000 to 1.2 million, 700,000 to 1.4 million, or 600,000 to 800,000. In this specification, the weight average molecular weight refers to a value converted to standard polystyrene measured by GPC (Gel Permeation Chromatography), and unless otherwise specified, the molecular weight refers to the weight average molecular weight. If the molecular weight of the polymer is too low, the cohesive strength of the pressure-sensitive adhesive layer may be reduced, and if it is too high, the adhesive properties may be reduced. Therefore, an appropriate molecular weight can be selected taking these factors into consideration.

[0108] In addition to the above components, the pressure-sensitive adhesive composition may further contain various additives known in the art, as needed. For example, the pressure-sensitive adhesive composition may further contain a tackifier. Examples of tackifiers that may be used include, but are not limited to, rosin ester-based or styrene-based tackifiers, and an appropriate type may be selected and used as needed. The content of the tackifier is also not particularly limited and may be adjusted taking into account factors such as the peel strength from the electrode assembly. In one example, the tackifier may be used in a ratio of 1 to 25 parts by weight per 100 parts by weight of the polymer.

[0109] The pressure-sensitive adhesive composition may further contain additives such as an initiator such as a thermal initiator or a photoinitiator, an epoxy resin, a curing agent, a UV stabilizer, an antioxidant, a color-matching agent, a reinforcing agent, a filler, an antifoaming agent, a surfactant, a photopolymerizable compound such as a multifunctional acrylate, or a plasticizer, within a range that does not affect the intended effect.

[0110] As an example, the polymer contained in the pressure-sensitive adhesive composition may be produced by photopolymerization by selecting a suitable, generally well-known photoinitiator. Examples of the photoinitiator include organic peroxides such as benzoyl peroxide, 1,1-bis(tert-butylperoxy)-3,3,5-triethylcyclohexane, tert-butyl peroxyacetate, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisopropyl carbonate, di-2-ethylhexyl peroxydicarbonate, diisopropyl peroxydicarbonate, di-3-methoxybutyl peroxydicarbonate, di-3,3,5-trimethylhexanoyl peroxide, di-tert-butyl peroxide, lauroyl peroxide, dicumyl peroxide, and methyl ether ketone peroxide; butyl hydroperoxide; The photopolymerization method may be applied by, but is not limited to, hydroperoxides such as peroxide and cumyl hydroperoxide; oxidizing agents such as hydrogen peroxide, ammonium peroxydisulfate, nitric acid and its salts, perchloric acid and its salts, sulfuric acid and its salts, hypochlorous acid and its salts, permanganic acid and its salts, chromic acid and its salts, lead dioxide, manganese dioxide, copper oxide, iron chloride, fluorine, chlorine, bromine, and iodine; reducing agents such as sodium borohydride, formaldehyde, acetaldehyde, amines, and hydrazine; azo compounds such as azobisisobutyronnitrile (hereinafter referred to as AIBN); irradiation with heat, ultraviolet light, or high-energy wavelengths; electron transfer within an electrolyte; and the like.

[0111] The content of the photoinitiator is not particularly limited, but may be 0.01 to 5 parts by weight, for example, 0.01 to 1 part by weight, or 0.01 to 0.5 parts by weight, relative to 100 parts by weight of the total monomer mixture.

[0112] The pressure-sensitive adhesive layer 11 can be formed, for example, by coating a coating liquid containing the above-mentioned polymer and a multifunctional crosslinking agent on the porous support 12, and inducing a crosslinking reaction between the polymer and the multifunctional crosslinking agent under appropriate conditions.

[0113] The thickness of the pressure-sensitive adhesive layer 11 is not particularly limited and can be appropriately selected depending on the intended use, for example, the desired peel strength, etc. The pressure-sensitive adhesive layer 11 may be formed to have a thickness of, for example, 2 μm to 100 μm, 3 μm to 50 μm, 4 μm to 25 μm, 2 μm to 15 μm, 4 μm to 10 μm, 4 μm to 9 μm, 4 μm to 7 μm, 5 μm to 9 μm, or 5 μm to 7 μm, but this can be changed depending on the purpose.

[0114] The adhesive tape 10 may be an adhesive tape 10 that is attached to the inner portion 1c of the electrode assembly in a secondary battery. In addition, the adhesive tape 10 according to an embodiment of the present application does not have an excessively high initial peel strength of the adhesive layer 11, and includes the adhesive layer 11 containing the monomer having the polar functional group described above. When the adhesive tape 10 comes into contact with an electrolyte in a secondary battery, the adhesive layer 11 absorbs the electrolyte and expands, so that the peel strength of the adhesive layer 11 can be adjusted to be low enough to allow the adhesive tape 10 to be detached from the electrode assembly.

[0115] In one example, the adhesive tape 10 of the present application may have an initial release strength sufficient to secure the electrode assembly and to be detached from the electrode assembly upon contact with an electrolyte. If the initial release strength of the electrode assembly is too high, the adhesive layer 11 may be difficult to detach from the electrode assembly 22 even after contact with the electrolyte. For example, the adhesive layer 11 may have a peel strength of 370 gf / 25 mm or less, e.g., 350 gf / 25 mm or less, 315 gf / 25 mm or less, or 312 gf / 25 mm or less, measured at room temperature from glass at a peel speed of 5 mm / sec and a peel angle of 180 degrees. The lower limit of the peel strength of the adhesive layer 11 from glass is not particularly limited. For example, if the adhesive layer has a very low initial release strength, the adhesive layer loses its adhesive strength upon contact with the electrolyte, thereby preventing the adhesive tape from detaching from the electrode assembly and electrode disconnection. However, if the initial peel strength of the adhesive layer 11 is too low, the electrode assembly may dissolve without coming into contact with the electrolyte before being housed in a can. Considering this, the lower limit of the peel strength of the adhesive layer 11 from glass may be adjusted to 5 gf / 25 mm or more, for example, 10 gf / 25 mm or more, 20 gf / 25 mm or more, 30 gf / 25 mm or more, 40 gf / 25 mm or more, 50 gf / 25 mm or more, 60 gf / 25 mm or more, 70 gf / 25 mm or more, 80 gf / 25 mm or more, 85 gf / 25 mm or more, or 88 gf / 25 mm or more. When the adhesive layer 11 has a peel strength to glass within the above range, even when the adhesive layer 11 is attached to the inside 1c of the electrode assembly 1, it can exhibit an appropriate initial peel strength to be detached when it comes into contact with an electrolyte, and when the adhesive tape 10 comes into contact with an electrolyte, it can form a three-dimensional structure with a specific surface roughness.

[0116] Furthermore, when the adhesive tape 10 of the present application comes into contact with an electrolyte, the adhesive layer 11 absorbs the electrolyte and expands to form a three-dimensional structure, and the peel strength of the adhesive layer 11 can be adjusted to be low enough to allow the adhesive layer 11 to be detached from the electrode assembly, thereby allowing the adhesive layer 11 to be detached from the attachment surface of the inner part 1c of the electrode assembly. In one example, the adhesive tape 10 can be detached from the attachment surface of the electrode assembly after coming into contact with the electrolyte, and preferably, 50% or more, for example, 60% or more, 70% or more, or 80% or more of the area of ​​the adhesive tape 10 attached to the inner part 1c of the electrode assembly can be detached.

[0117] The thickness of the adhesive tape 10 is not particularly limited and can be appropriately selected depending on the desired peel strength, etc. The adhesive tape 10 may be formed to have a thickness of, for example, 10 μm to 100 μm, 15 μm to 75 μm, 20 μm to 45 μm, 15 μm to 40 μm, 20 μm to 40 μm, or 20 μm to 30 μm, but this may be changed depending on the purpose. If the thickness of the adhesive tape 10 is too thin, the effect of the expansion of the adhesive layer 11 of the adhesive tape 10 may be difficult to achieve. Conversely, if the thickness is too thick, the thickness of the electrode assembly increases accordingly, which may result in increased damage to the electrode assembly due to reduced processability when inserted into a battery case, or may result in a decrease in capacity for the same size.

[0118] The adhesive tape 10 may further include a release sheet attached to the adhesive layer 11 to protect the adhesive layer 11 before use of the tape.

[0119] Another embodiment of the present specification provides a secondary battery including the electrode assembly described above and a battery case for accommodating the electrode assembly. The secondary battery may be embodied in various forms, depending on the type of electrode assembly wound up, the type of battery case, and the method of sealing the wound electrode assembly. For example, the secondary battery may be a cylindrical secondary battery, a prismatic secondary battery, or a pouch-type secondary battery.

[0120] In yet another embodiment of the present specification, the electrode assembly may be in the form of a roll having a circular cross section perpendicular to the mandrel axis.

[0121] The type of the can 21 in which the electrode assembly 22 is housed is not particularly limited, and may be, for example, a cylindrical can 21 of a type known in the art.

[0122] The secondary battery 20 may be manufactured, for example, by attaching the adhesive tape 10 to the electrode assembly 22, placing it inside a can 21, injecting an electrolyte into the can 21, and then sealing the can 21.

[0123] The type of electrolyte, which is a fluid that deforms, e.g., expands, the adhesive layer 11 of the adhesive tape 10, is not particularly limited, and any electrolyte known in the art may be used depending on the type of battery. For example, when the battery is a lithium secondary battery, the electrolyte may contain, for example, a non-aqueous organic solvent and a lithium salt. The lithium salt is dissolved in the organic solvent and acts as a lithium ion source in the battery, promoting the migration of lithium ions between the positive electrode and the negative electrode. Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiCF3SO3, LiN(CF3SO2)3, Li(CF3SO2)2N, LiC4F9SO3, LiClO4, LiAlO4, LiAlCl4, and LiN(C x F 2x +1SO2)(C y F2 y+1SO2) (where x and y are natural numbers, and examples include those containing one or more of LiCl, LiI, and lithium bisoxalate borate as supporting electrolyte salts. The concentration of the lithium salt in the electrolyte can be varied depending on the application, and is usually used in the range of 0.1M to 2.0M.The organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move, and examples thereof include benzene, toluene, fluorobenzene, 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, 1,2,3-trifluorobenzene, 1,2,4-trifluorobenzene, chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, iodobenzene, and the like. Iodobenzene, 1,2-diiodobenzene, 1,3-diiodobenzene, 1,4-diiodobenzene, 1,2,3-triiodobenzene, 1,2,4-triiodobenzene, fluorotoluene, 1,2-difluorotoluene, 1,3-difluorotoluene, 1,4-difluorotoluene, 1,2,3-trifluorotoluene, 1,2,4-trifluorotoluene, chlorotoluene, 1,2-dichlorotoluene, 1,3-dichlorotoluene, 1,4-dichlorotoluene, 1,2,3-trichlorotoluene, 1 , 2,4-trichlorotoluene, iodotoluene, 1,2-diiodotoluene, 1,3-diiodotoluene, 1,4-diiodotoluene, 1,2,3-triiodotoluene, 1,2,4-triiodotoluene, R-CN (wherein R is a hydrocarbon group having a linear, branched or cyclic structure and having 2 to 50 carbon atoms, and the hydrocarbon group may contain a double bond, an aromatic ring, an ether bond, or the like), dimethylformamide, dimethyl acetate, xylene, cyclohexane, tetrahydrofuran, 2-methyltetrahydrofuran, cyclohexane ... Examples of the solvent include, but are not limited to, one or more of: diisohexanone, ethanol, isopropyl alcohol, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate, propylene carbonate, methyl propionate, ethyl propionate, methyl acetate, ethyl acetate, propyl acetate, dimethoxyethane, 1,3-dioxolane, diglyme, tetraglyme, ethylene carbonate, propylene carbonate, γ-butyrolactone, sulfolane, valerolactone, decanolide, and mevalonolactone.

[0124] In one embodiment of the present specification, the secondary battery may be a cylindrical secondary battery having a form factor ratio (defined as the value obtained by dividing the diameter by the height of a cylindrical battery, i.e., the ratio of the height (H) to the diameter (Φ)) of greater than 0.4. Here, the form factor refers to values ​​indicating the diameter and height of a cylindrical secondary battery.

[0125] Batteries with a form factor ratio of approximately 0.4 or less have traditionally been used. These include 18650 cells and 21700 cells. The 18650 cell has a diameter of approximately 18 mm and a height of approximately 65 mm, resulting in a form factor ratio of approximately 0.277. The 21700 cell has a diameter of approximately 21 mm and a height of approximately 70 mm, resulting in a form factor ratio of approximately 0.300.

[0126] A cylindrical secondary battery according to an embodiment of the present specification may be a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the number representing the form factor, the first two digits represent the diameter of the cell, the next two digits represent the height of the cell, and the final digit 0 indicates that the cross section of the cell is circular.

[0127] The secondary battery according to one embodiment of the present specification may be a cylindrical secondary battery having a cylindrical cell with a diameter of 46 mm, a height of 110 mm, and a form factor ratio of 0.418.

[0128] The secondary battery according to one embodiment of the present specification may be a cylindrical secondary battery having a cylindrical cell with a diameter of 48 mm, a height of 75 mm, and a form factor ratio of 0.640.

[0129] The secondary battery according to one embodiment of the present specification may be a cylindrical secondary battery having a cylindrical cell with a diameter of 48 mm, a height of 110 mm, and a form factor ratio of 0.418.

[0130] The secondary battery according to one embodiment of the present specification may be a cylindrical secondary battery having a cylindrical cell with a diameter of 48 mm, a height of 80 mm, and a form factor ratio of 0.600.

[0131] The secondary battery according to one embodiment of the present specification may be a cylindrical secondary battery having a cylindrical cell with a diameter of 46 mm, a height of 80 mm, and a form factor ratio of 0.575.

[0132] Another embodiment of the present specification provides a secondary battery including the electrode assembly 1 described above and a battery case for accommodating the electrode assembly 1.

[0133] 11 illustrates a secondary battery 20 housed in a battery case that houses a wound electrode assembly 1. The electrode assembly 1 has a circular cross section perpendicular to the mandrel axis, and the battery case may be cylindrical. The battery case may include a can 21 and a cap assembly 22.

[0134] The can 21 may have a columnar structure with a space formed therein. The can 21 may accommodate a battery assembly 1 including electrodes and a separator, and an electrolyte (not shown) in the space. One side of the can 21 may have an open structure, and the other side may have a sealed structure. Here, the one side and the other side of the can 21 refer to the ends located at the top and bottom along the direction of gravity or the central axis of the can 21.

[0135] Can 21 may be constructed from a lightweight, conductive metallic material such as aluminum or an aluminum alloy.

[0136] A cap assembly 22 may be coupled to the top of the can 21 and may include a top cap, a safety vent, and a current interrupt device.

[0137] The top cap protrudes from the top of the cap assembly 22 and serves as an electrode terminal for electrical connection to the outside. The safety vent can release high-pressure gas when gas is generated inside the battery above a predetermined level due to an increase in withstand pressure, and the current interruption device can interrupt current when the battery withstand voltage increases.

[0138] The top cap may be coupled to the top of the can 21. That is, the top cap may be coupled to a crimp portion located at the top of the can 21.

[0139] The secondary battery 20 according to the present invention may include a gasket between the crimped portion and the top cap, which can increase the sealing force of the case.

[0140] The top cap may include a protrusion protruding upward in the direction of gravity, a frame coupled to the gasket, and a connecting portion connecting the protrusion and the frame.

[0141] The safety vent may be located under the top cap and coupled to an end portion of the top cap. The safety vent may be in contact with the end portion of the top cap for a predetermined length, and the portion of the safety vent excluding the contact length may be spaced a predetermined distance from the top cap.

[0142] The safety vent may be bent at least one time. For example, the safety vent may have two notches in the portion that does not contact the top cap. That is, the safety vent 12 may be bent by the notches, and the center of the safety vent may be depressed to form a concave central portion. The safety vent may then have a venting portion that connects the end portion that contacts the top cap and the concave central portion.

[0143] The current interrupting element may be positioned below the safety vent and may be in at least partial contact with the safety vent.

[0144] The current interrupting element may include a central portion protruding toward the safety vent and a CID filter portion positioned outside the central portion, so that the cap assembly 22 allows the central portion of the current interrupting element to come into contact with the recessed central portion of the safety vent.

[0145] The cap assembly 22 according to the present invention may be provided with a CID gasket at the end of the CID filter portion, which can prevent the safety vent from being contacted at a portion other than the center of the current interruption device.

[0146] Another embodiment of the present disclosure provides a battery pack including two or more of the above-described secondary batteries. Figure 12 is a diagram schematically illustrating the configuration of a battery pack according to an embodiment of the present disclosure.

[0147] 12, a battery pack 200 according to an embodiment of the present invention includes an assembly of electrically connected secondary battery cells 201 and a pack housing 202 that accommodates the assembly. The cylindrical secondary battery cells 201 are the battery cells according to the above-described embodiment. For ease of illustration, components such as bus bars for electrically connecting the cylindrical secondary battery cells 201, a cooling unit, and external terminals are omitted from the drawing.

[0148] Another embodiment of the present specification provides a vehicle including the above-described battery pack 200. The vehicle may be any vehicle that moves cargo, people, etc., or performs work while moving, and may be a bicycle, heavy equipment, agricultural equipment, a car, a bus, an airplane, etc.

[0149] The battery pack 200 may be mounted on a vehicle V. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle V may be a four-wheeled vehicle or a two-wheeled vehicle. FIG. 13 is a diagram illustrating the vehicle V including the battery pack 200 of FIG. 12.

[0150] 13, a vehicle V according to an embodiment of the present disclosure includes a battery pack 200 according to an embodiment of the present disclosure. The vehicle V operates by receiving power from the battery pack 200 according to an embodiment of the present disclosure. [Example]

[0151] The present invention will be described in more detail below with reference to examples. However, the following examples are intended to illustrate the present invention only and are not intended to limit the present invention.

[0152] [Manufacturing Example 1] Polymer production A 1000cc reactor equipped with a nitrogen gas reflux and a cooling device for easy temperature control was charged with a monomer mixture consisting of 58 parts by weight of n-butyl acrylate (n-BA), 40 parts by weight of methoxyethyl acrylate (MEA), and 2 parts by weight of hydroxybutyl acrylate (HBA), 0.02 parts by weight of n-dodecanethiol as a chain transfer agent, and 150 parts by weight of ethyl acetate (EAc) as a solvent. The mixture was then purged with nitrogen gas at 60°C for 60 minutes to remove oxygen, and then maintained at 60°C. After homogenizing the mixture, 0.04 parts by weight of azobisisobutyronitrile (AIBN) as a reaction initiator was added. The mixture was reacted for 8 hours to produce a polymer having a weight average molecular weight of 800,000. In the above, "parts by weight" means "wt%."

[0153] A pressure-sensitive adhesive composition was prepared by adding 0.3 parts by weight of a tolylene diisocyanate adduct of trimethylolpropane as a multifunctional isocyanate crosslinking agent to 100 parts by weight of the prepared polymer to an ethyl acetate solution, diluting it to an appropriate concentration in consideration of coating properties, and uniformly mixing the mixture.

[0154] The adhesive composition was coated on one side of a release film to a thickness of 3 μm and dried, and then transferred onto a porous substrate. The release film was then removed to prepare an adhesive tape with a thickness of 19 μm, a length of 60 mm, and a width of 10 mm.

[0155] In this case, the porous support has a porosity of 47%, a thickness of 16 μm, and a tensile strength in the machine direction (MD) of 2040 kgf / cm. 2 The porous support is made of polyethylene (PE) with a tensile elongation of 125% in the MD direction.

[0156] [Experimental Example 1] Electrode assembly and battery manufacturing As shown in FIG. 15, an electrode assembly including a negative electrode, a positive electrode, and a separator was stacked, and the prepared adhesive tape was attached to the adhesive tape position shown in FIG. 15. The stacked electrode assembly was then wound up to prepare a jelly roll (J / R) with a cross-sectional diameter of 17.2 mm.

[0157] The jelly roll assembly was inserted into a cylindrical can (cross-sectional diameter: 17.5 mm), and then a carbonate-based electrolyte was injected into the can and sealed to complete the test battery.

[0158] On the other hand, a battery of the above example to which no adhesive tape was attached was used as a comparative example (Ref).

[0159] The batteries of the examples and comparative examples were charged and discharged 20 times and 50 times under the following conditions, and then the deformation of the jelly roll was observed.

[0160] <Test Condition> Temperature: 25℃ Charge:4.25V 1C 50mA cut, rest 10min Discharge:1C 2.5V cut, rest 20min In order to check the deformation of the batteries after 20 and 50 charge / discharge cycles, two each of the Example (Test) and Comparative Example (Ref) were manufactured in the same manner and divided into #1 and #2. CT images were taken using an XSCAN-8225 device at 225 kV and a frame rate of 3 fps. The results are shown in FIG. 14.

[0161] 14, the battery of the comparative example (Ref) experienced deformation on the mandrel side due to electrode expansion during charge and discharge, while the battery of the example (Test) in which adhesive tape was applied suppressed deformation because the separator was physically reinforced by the adhesive tape. In this case, mandrel (core) deformation can damage the electrodes, reducing battery performance and, in severe cases, even damage the separator, potentially causing an internal short circuit. Therefore, it is important to reduce deformation.

[0162] [Experimental Example 2] Lithium metal deposition confirmed after disassembly In Experimental Example 1, the battery of Example (Test) that had been charged and discharged 50 times was disassembled in a fully charged state of 4.2 V, and the presence or absence of lithium metal deposition was observed. A photograph of this observation is shown in FIG. 16.

[0163] Before charging, the negative electrode is black in color due to carbon, but after charging, it turns yellow when lithium metal is intercalated, and shows gray when lithium metal is precipitated.

[0164] In the battery of the Example, the area where the adhesive tape is attached is the negative electrode facing the positive electrode, and if a general tape is attached, which absorbs the electrolyte and expands, and does not form an ion exchange path, it will hinder the movement of lithium ions and cause lithium metal deposition in the surrounding area.On the other hand, the adhesive tape made in the Preparation Example forms an ion migration path that allows ions to move, and it was confirmed from Figure 15 that lithium metal deposition did not occur.

[0165] Although the present invention has been described above with reference to preferred embodiments, it should be understood that those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention as set forth in the claims. [Explanation of symbols]

[0166] 1...electrode assembly 1a Mandrel 1b: Outermost 1c...Internal 2...Positive electrode 2a...Positive electrode current collector 2b...Cathode active material layer 2b'...first positive electrode active material layer 2b''...Second positive electrode active material layer 2c Positive electrode tab 2d...Cathode active material layer section 2d'...First positive electrode active material layer section 2d''...Cathode active material layer section 2e: Positive electrode uncoated area 4...Separation membrane 4a...1st separation membrane 4b...Second separation membrane 5...Negative electrode 5a...Negative electrode current collector 5b...Negative electrode active material layer 5b'...first negative electrode active material layer 5b''...Second negative electrode active material layer 5c Negative electrode tab 10. Adhesive tape 11 Adhesive layer 12...Porous support 20...Secondary battery 21 cans 22 Cap assembly 200 battery pack 201 Cylindrical battery cells 202 Pack Housing 65V...Transportation

Claims

1. An electrode assembly in which a positive electrode, a negative electrode, and a separator provided between the positive electrode and the negative electrode are stacked and wound, The electrode assembly further includes an adhesive tape attached to the inside of the wound electrode assembly, The adhesive tape includes a porous support and an adhesive layer provided on the porous support, the adhesive layer contacting an electrolyte solution and absorbing the electrolyte solution to expand and form an ion migration path; The adhesive layer absorbs the electrolyte solution after coming into contact with the electrolyte solution, and expands to form a three-dimensional structure that is detachable from the electrode assembly.

2. The electrode assembly of claim 1 , wherein the adhesive tape is adhered to at least one of the space between the positive electrode and the separator and the space between the negative electrode and the separator.

3. the positive electrode and the negative electrode each include a current collector and an active material layer provided on at least one surface of the current collector; 2. The electrode assembly of claim 1, wherein the adhesive tape is adhered to at least one of a space between the mandrel-side end of the positive electrode active material layer and the separator and a space between the mandrel-side end of the negative electrode active material layer and the separator.

4. the positive electrode includes a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector, The electrode assembly of claim 1 , wherein the adhesive tape is adhered to cover an end of the positive electrode active material layer and a surface of the positive electrode current collector adjacent to the end of the positive electrode active material layer.

5. the positive electrode includes a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector, The positive electrode is two or more active material layer portions spaced apart in the winding direction of the electrode assembly, each including the positive electrode current collector and the positive electrode active material layer; and a blank portion between the two or more active material layer portions, where the positive electrode current collector is not provided with the positive electrode active material layer; Including, The electrode assembly of claim 1 , wherein the adhesive tape is adhered to cover the uncoated portion and an end of the positive electrode active material layer on the uncoated portion side.

6. The electrode assembly according to claim 1 , wherein the positive electrode and the negative electrode each include a current collector and an active material layer provided on both sides of the current collector.

7. The electrode assembly according to claim 6 , wherein the mandrel-side end of the negative electrode active material layer is closer to the mandrel-side end of the separator than the mandrel-side end of the positive electrode active material layer in the winding direction of the electrode assembly.

8. The negative electrode includes an active material layer portion in which the active material layer is provided on the current collector, and a plain portion where the active material layer is not provided at both ends of the current collector in the winding direction of the electrode assembly; Including, The electrode assembly according to claim 7 , wherein the adhesive tape is adhered onto the mandrel-side uncoated portion of the negative electrode.

9. The adhesive tape is The electrode assembly according to claim 8 , wherein the mandrel-side end of the positive electrode active material layer is adhered to a mandrel-side uncoated portion of the negative electrode facing the mandrel side.

10. The adhesive tape is The electrode assembly according to claim 9 , wherein the mandrel-side end of the positive electrode active material layer is provided on one of both surfaces of the mandrel-side uncoated portion of the negative electrode facing the mandrel side.

11. The electrode assembly of claim 6 , wherein the negative electrode has a negative electrode tab formed on a mandrel-side end of the negative electrode current collector.

12. The electrode assembly of claim 1 , wherein the adhesive layer comprises an acrylate adhesive having an ethylene oxide side chain.

13. An electrode assembly according to any one of claims 1 to 12, and a battery case for accommodating the electrode assembly; A secondary battery comprising:

14. The secondary battery according to claim 13 , wherein the electrode assembly has a circular cross section perpendicular to the mandrel axis, and the battery case has a cylindrical shape.

15. A battery pack comprising two or more secondary batteries according to claim 13.

16. A vehicle comprising the battery pack of claim 15.

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