Electrode assembly, and secondary battery, battery pack, and means of transport including the same.

Abstract

The present invention provides an electrode assembly comprising a positive electrode, a negative electrode, and a separation membrane provided between the positive and negative electrodes, which are laminated and wound together; a secondary battery, a battery pack, and a means of transport including the same. [Solution] This specification relates to an electrode assembly comprising a positive electrode, a negative electrode, and a separation membrane provided between the positive electrode and the negative electrode, which are laminated and wound together, and further comprising an adhesive tape adhered to the inside of the wound electrode assembly, wherein the adhesive tape comprises a porous support and an adhesive layer on the porous support that, after contact with an electrolyte, absorbs the electrolyte and expands to form an ion transport path, an electrode assembly, and a secondary battery, a battery pack, and a transport means comprising the same.

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, and all of its contents are incorporated herein by reference.

[0002] This specification relates to a positive electrode, a negative electrode, an electrode assembly in which a separator provided between the positive electrode and the negative electrode is laminated and wound, a secondary battery, a battery pack, and a transportation means including the same.

Background Art

[0003] In the case of a cylindrical, prismatic or pouch-type battery, a long electrode with a determined width is wound together with a separator to manufacture an electrode assembly in the form of a jelly roll. A cylindrical battery manufactured by inserting such a jelly roll-type electrode assembly into a battery case repeats contraction / expansion of the electrodes during charge and discharge. In particular, when an in-tab is located at the core of the jelly roll-type electrode assembly or a silicon-based active material is added to the negative electrode, the degree of contraction / expansion of the electrode assembly increases, and the pressure acting on the core portion of the electrode assembly increases significantly.

[0004] Recently, with the increasing low resistance / high capacity design, the jelly roll-type electrode assembly increasingly includes a plurality of tabs or a silicon-based active material is added, thereby increasing the deformability of the electrode assembly located in the core portion due to the contraction / expansion of the electrode assembly. In particular, when the separator located between the negative electrode and the positive electrode is damaged, there is a problem that the negative electrode and the positive electrode come into direct contact and heat generation and ignition occur due to an internal short circuit.

[0005] In order to solve the problems of damage to the separator due to deformation of such an electrode assembly and occurrence of an internal short circuit, there is an actual situation where it is necessary to develop a technology that can protect the positive electrode and the separator in this area and suppress the occurrence of an internal short circuit.

Summary of the Invention

[0006] This specification aims to provide an electrode assembly comprising a positive electrode, a negative electrode, and a separator membrane provided between the positive and negative electrodes, which are laminated and wound together, as well as a secondary battery, a battery pack, and a means of transport including the same. [Means for solving the problem]

[0007] One embodiment of this specification provides an electrode assembly comprising a positive electrode, a negative electrode, and a separation membrane provided between the positive electrode and the negative electrode, which are laminated and wound together, further comprising an adhesive tape adhered to the inside of the wound electrode assembly, wherein the adhesive tape comprises a porous support and an adhesive layer provided on the porous support, the adhesive layer which, after contact with an electrolyte, absorbs the electrolyte and expands to form an ion transport path, thereby providing an electrode assembly.

[0008] In other embodiments of this specification, the adhesive tape may be adhered to at least one of the spaces between the positive electrode and the separator membrane, and between the negative electrode and the separator membrane.

[0009] In other embodiments of this 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 the spaces between the mandrel-side end of the active material layer of the positive electrode and the separator membrane, and between the mandrel-side end of the active material layer of the negative electrode and the separator membrane.

[0010] In yet another embodiment of this specification, the positive electrode includes 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 so as to cover the edges of the positive electrode active material layers and the surface of the positive electrode current collector adjacent to the edges of the positive electrode active material layers.

[0011] In other embodiments of this 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 at least one of the positive electrode and the negative electrode includes two or more active material layer portions provided on the current collector, spaced apart in the winding direction of the electrode assembly; and a plain portion between the two or more active material layer portions where the current collector is not provided with the active material layer, and the adhesive tape may be adhered so as to cover the plain portion and the plain portion side end of the active material layer.

[0012] In yet another embodiment of this 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 other embodiments of this specification, the mandrel-side end of the negative electrode active material layer may be closer to the mandrel-side end of the positive electrode active material layer than the mandrel-side end of the positive electrode active material layer, in the winding direction of the electrode assembly.

[0014] In yet another embodiment of this specification, the negative electrode includes an active material layer portion on the current collector and plain portions on both ends of the current collector in the winding direction of the electrode assembly where the active material layer is not provided, and the adhesive tape may be adhered to the plain portion on the mandrel side of the negative electrode.

[0015] In other embodiments of this specification, the adhesive tape may be adhered to a plain area where the mandrel-side end of the positive electrode active material layer faces the mandrel.

[0016] In yet another embodiment of this specification, the adhesive tape may be provided on the mandrel side of the plain surface on both sides of the mandrel-side portion that faces the mandrel side of the mandrel-side end of the positive electrode active material layer.

[0017] In other embodiments of this specification, the negative electrode may have a negative electrode tab formed on the mandrel-side end of the negative electrode current collector.

[0018] In another embodiment of the present specification, the adhesive layer may include an acrylate adhesive having an ethylene oxide side chain.

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

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

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

[0022] Another embodiment of the present specification provides a transportation means including the battery pack described above. The transportation means is anything that moves or moves to work on luggage, people, etc., and may be a bicycle, heavy equipment, agricultural equipment, automobile, bus, airplane, etc.

Advantages of the Invention

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

[0024] The electrode assembly according to an embodiment of the present specification includes an adhesive tape capable of ion movement, and thus has the advantage of not interfering with ion movement due to the attachment of the tape, so that the capacity of the battery is not reduced or the loss of capacity is small.

Brief Description of the Drawings

[0025] [Figure 1] It is a drawing showing a state where the adhesive tape of the 1-1 embodiment of the present specification is attached. [Figure 2]This is a drawing showing the state in which the adhesive tape of the first and second embodiments of this specification is attached. [Figure 3] This is a drawing showing the state in which the adhesive tape of the second-first embodiment of this specification is attached. [Figure 4] This is a drawing showing the state in which the adhesive tape of the second-second embodiment of this specification is attached. [Figure 5] This is a drawing showing the state in which the adhesive tape of the third embodiment of this specification is attached. [Figure 6] This is a drawing showing the state in which the adhesive tape of the 4-1 embodiment of this specification is attached. [Figure 7] This is a drawing showing the state in which the adhesive tape of the 4-2 embodiment of this specification is attached. [Figure 8] (a) is a diagram illustrating a cross-section of an adhesive tape according to one embodiment of this specification, and (b) is a diagram illustrating a cross-section of an adhesive tape according to yet another embodiment of this specification. [Figure 9] This shows the winding process for the electrode stack. [Figure 10] This is a perspective view of the wound electrode stack. [Figure 11] This is a vertical cross-sectional view of a secondary battery housed in a battery case containing a wound electrode stack. [Figure 12] This diagram schematically shows the configuration of a battery pack according to an embodiment of the present invention. [Figure 13] Figure 12 is a diagram illustrating the automobile V, including the battery pack 200. [Figure 14] The CT images of the mandrel portion of the secondary battery after charging and discharging were compared between the example and comparative example with and without adhesive tape according to this embodiment. [Figure 15] This is a drawing showing the state in which the adhesive tape of the first to third embodiments of this specification is attached. [Figure 16] This photograph shows the presence or absence of lithium metal deposition after disassembling a battery in an example that underwent 50 charge-discharge cycles. [Modes for carrying out 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] Figure 9 shows the winding process of electrode assembly 1, and Figure 10 is a perspective view of the wound electrode stack.

[0028] First, the positive electrode 2, the negative electrode 5, and the separation membrane 4 provided between the positive electrode 2 and the negative electrode 5 can be stacked.

[0029] The separation membrane may include two separation membranes, as shown in Figure 9, a first separation membrane 4a between the negative electrode 5 and the positive electrode 2, and an additional second separation membrane 4b on the side opposite to the side of the positive electrode 2 that is in contact with the first separation membrane 4a. Specifically, the second separation membrane 4b, the positive electrode 2, the first separation membrane 4a, and the negative electrode 5 may be stacked in sequence.

[0030] In the winding direction, as shown in Figure 9, the second separation membrane 4b, the positive electrode 2, the first separation membrane 4a, and the negative electrode 5 may be sequentially stacked and wound towards the negative electrode 5 side. When wound in this manner, the separation membrane may be exposed to the outermost layer 1b in the wound electrode assembly.

[0031] If necessary, the winding direction may be reversed from the winding direction illustrated in Figure 9. When winding in this manner, the negative electrode 5 or the negative electrode 5 and the separation membrane 4 may be exposed together on the outermost casing 1b in the wound electrode assembly. In this case, when the negative electrode is exposed on the outermost casing 1b, either only the blank portion of the outer casing side negative electrode without the negative electrode active material layer is exposed, or the outer casing side negative electrode active material layer portion may be exposed together with the blank portion of the outer casing side negative electrode on the outermost casing 1b.

[0032] As shown in Figure 10, the wound electrode assembly 1 includes an adhesive tape 10 attached to the inside 1c of the electrode assembly 1.

[0033] In this specification, the interior 1c to which the adhesive tape is attached refers to the portion of the wound electrode assembly excluding the outermost 1b. In this case, if the wound electrode assembly is considered a column, the outermost 1b means the side surface exposed to the outside, and the interior 1c to which the adhesive tape is attached includes the entire inner region of the column 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 sides of the positive electrode current collector 2a and 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 opposite side of 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 the blank positive electrode portion 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 on the positive electrode current collector 2a, and a positive electrode blank portion 2e on one or both ends of the positive electrode current collector 2a where the positive electrode active material layer is not provided. In this case, the positive electrode tab 2c may be located on the positive electrode blank portion 2e located on one or both ends of the positive electrode current collector 2a, and preferably on the positive electrode blank portion 2e at one end.

[0038] In another embodiment, the positive electrode 2 may include a blank positive electrode portion 2e at the outer end of the positive electrode current collector 2a where the positive electrode active material layer is not provided, and a positive electrode tab 2c may be formed on the blank positive electrode portion 2e.

[0039] In another embodiment, the positive electrode 2 may include two or more positive electrode active material layer portions 2d, each having a positive electrode active material layer, spaced apart in the longitudinal direction on the positive electrode current collector 2a, and a positive electrode blank 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 located in the positive electrode blank portion 2e between the two or more positive electrode active material layer portions 2d, and preferably in the positive electrode blank portion 2e located 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 positive electrode blank portions.

[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, and the first positive electrode active material layer 2b' provided on one side of the positive electrode current collector 2a and the 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 sides of the negative electrode current collector 5a and 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 opposite side of 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 the blank portion of the negative electrode 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 on the negative electrode current collector 5a, and a negative electrode blank portion on one or both ends of the negative electrode current collector 5a where the negative electrode active material layer is not provided. In this case, the negative electrode tab 5c may be located in the negative electrode blank portion located on one or both ends of the negative electrode current collector 5a, and preferably, it may be located in the negative electrode blank portions at both ends.

[0044] In another embodiment, the negative electrode 5 may include a blank negative electrode portion at the mandrel-side end of the negative electrode current collector 5a where the active material layer is not provided, and a negative electrode tab 5c may be formed on the blank negative electrode 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, and the first negative electrode active material layer 5b' provided on one side of the negative electrode current collector 5a and the second negative electrode active material layer 5b'' provided on the other side may have the same or different lengths.

[0046] In another embodiment, the positive electrode 2 is spaced apart in the winding direction of the electrode assembly 1 and includes two positive electrode active material layer portions 2d', 2d''; on the positive electrode current collector 2a, each having the positive electrode active material layer 2b, and a blank positive electrode portion 2e between the two active material layer portions where the positive electrode current collector 2a does not have the positive electrode active material layer, with one positive electrode tab 2c formed on the blank positive electrode portion 2e. The negative electrode 5 includes two blank negative electrode portions on both ends of the negative electrode current collector 5a, each lacking the negative electrode active material layer, with one negative electrode tab 5c formed on each of the two blank negative electrode portions.

[0047] The electrode assembly 1 shown in Figures 1 to 7 is in a stacked state before winding, and may be wound in winding direction A or winding direction B. Depending on the winding direction and the length of each stack, the arrangement of electrodes exposed to the outside from the outermost layer of the wound electrode assembly will differ.

[0048] In the first embodiment, the adhesive tape 10 may be adhered to at least one of the following: between the positive electrode 2 and the separation membrane 4, and between the negative electrode 5 and the separation membrane 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 following: between the end of the positive electrode active material layer 2b and the separation membrane 4, and between the end of the negative electrode active material layer 5b and the separation membrane 4.

[0049] Figure 1 is a drawing showing the state in which an adhesive tape of a first-first embodiment of this specification is attached. In the first-first embodiment, the adhesive tape 10 may be adhered between the negative electrode 5 and the separation membrane 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, and the adhesive tape 10 may be adhered between the end of the negative electrode active material layer 5b and the separation membrane 4, preferably between the mandrel 1a side end of the negative electrode active material layer 5b and the separation membrane 4. In this case, the mandrel 1a side end of the negative electrode active material layer 5b means the portion in Figure 1 where winding begins in winding direction A or winding direction B, because this portion is located on the mandrel 1a side in the wound electrode assembly.

[0050] Figure 2 is a diagram showing the state in which the adhesive tape of the first and second embodiments of this specification is attached. In the first and second embodiments, the adhesive tape 10 may be adhered between the positive electrode 2 and the separation membrane 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, and the adhesive tape 10 may be adhered between the end of the positive electrode active material layer 2b and the separation membrane 4, preferably between the mandrel 1a side end of the positive electrode active material layer 2b and the separation membrane 4. In this case, the mandrel 1a side end of the positive electrode active material layer 2b means the portion in Figure 2 where winding begins in winding direction A or winding direction B, 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 so as to cover the end of the positive electrode active material layer 2b and the surface of the positive electrode current collector 2a adjacent to the end of the positive electrode active material layer 2b.

[0052] Figure 3 is a drawing showing the adhesive tape 10 attached according to the second-first embodiment of this specification. In the second-first embodiment, the positive electrode 2 includes a positive electrode current collector 2a and a positive electrode active material layer 2b provided on both sides of the positive electrode current collector 2a, and the adhesive tape 10 may be adhered so as to cover the ends of the positive electrode active material layer 2b and the surface of the positive electrode current collector 2a adjacent to the ends of the positive electrode active material layer 2b. In this case, the positive electrode tab may be provided at least one location on the blank positive electrode portion 2e where the positive electrode active material layer 2b is not provided, and this is not shown as an limitation. Furthermore, the adhesive tape 10 may be adhered to both sides corresponding to the positive electrode current collector 2a.

[0053] Figure 4 is a drawing showing the state in which the adhesive tape of the second-second embodiment of this specification is attached. In the second-second embodiment, the positive electrode 2 includes a positive electrode current collector 2a, a positive electrode active material layer 2b provided on both sides of the positive electrode current collector 2a, and a positive electrode tab 2c provided on a blank positive electrode portion 2e on the positive electrode current collector 2a where the positive electrode active material layer 2b is not provided, and the adhesive tape 10 is adhered so as to cover the end of the positive electrode active material layer 2b and the surface of the positive electrode current collector 2a adjacent to the end of the positive electrode active material layer 2b, and the adhesive tape 10 may also be adhered to the blank positive electrode portion 2e where the positive electrode tab 2c is provided.

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

[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 provided on the current collector, spaced apart in the winding direction of the electrode assembly, and a plain portion between the two or more active material layer portions where the current collector is not provided with the active material layer, and the adhesive tape 10 may be adhered so as to cover the plain portion and the end of the active material layer on the plain portion side.

[0056] Figure 5 is a drawing showing the state in which the adhesive tape of the third embodiment of this specification is attached. In the third embodiment, the positive electrode 2 includes a positive electrode current collector 2a and a positive electrode active material layer 2b provided on both sides of the positive electrode current collector 2a, and the positive electrode 2 includes two positive electrode active material layer portions 2d', 2d''; which are spaced apart in the winding direction of the electrode assembly 1 and which are provided with the positive electrode active material layer 2b on the positive electrode current collector 2a, and a positive electrode blank portion 2e between the two positive electrode active material layer portions which is not provided with the positive electrode active material layer 2b on the positive electrode current collector 2a, and the adhesive tape 10 may be adhered so as to cover the positive electrode blank portion 2e and the end of the positive electrode active material layer 2b on the positive electrode blank 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 negative electrode active material layer 5b may be closer to the mandrel 1a side end of the positive electrode active material layer 2b than the mandrel 1a side end of the separation membrane 4.

[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 the negative electrode current collector 5a; and a negative electrode plain portion in which the negative electrode active material layer 5b is not provided at 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 plain portion on the mandrel 1a side.

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

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

[0062] In the 4-1 and 4-2 embodiments, the mandrel 1a-side end of the first negative electrode active material layer 5b' provided on one side of the negative electrode current collector 5a is shorter than the mandrel 1a-side end of the second negative electrode active material layer 5b'' provided on the other side, and a negative electrode tab 5c may be provided at the end of the side 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 plain negative electrode portion on the mandrel 1a side.

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

[0064] In the fourth embodiment, the adhesive tape 10 may be provided on the side of the negative electrode current collector 5a on which the first negative electrode active material layer 5b' is provided, which is one of the two sides of the negative electrode plain portion that the mandrel 1a side end of the positive electrode active material layer 2b faces with reference to the first separator membrane 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] Figure 8 is an illustrative diagram showing a cross-section of the adhesive tape 10. The adhesive layer 11 may be provided on at least one surface of the porous support 12, and may be provided on the entire surface of the porous support 12 as in Figure 8(a), or it may be a pattern layer provided on one surface of the porous support 12 as in Figure 8(b).

[0067] The fact that the adhesive layer 11 is provided as a pattern layer means that the adhesive layer 11 may not be applied to the entire surface of the porous support 12 but may be provided at intervals, specifically meaning that there is a distinction between the parts where the adhesive is not applied and the parts where the adhesive is applied. In this case, the parts where the adhesive is not applied and the parts where the adhesive is applied may be repeated in a regular pattern, for example, the adhesive may be provided on at least one surface of the porous support 12 in the form of a pattern such as stripes, dots, waves, or a grid pattern.

[0068] The porous support 12 may be, for example, one or more films selected from the group consisting of acrylic film, polyolefin film, polyamide film, polycarbonate film, polyurethane film, cellulose acetate film, and 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 cellulose acetate resin or cellulose alkylate resin may be used, which is manufactured by applying a mixture containing the resin to an extrusion or casting process. As the cellulose alkylate, for example, cellulose acetate propionate or cellulose acetate butyrate may be used.

[0070] The method for producing the porous support 12 using the resin is not particularly limited, and for example, a conventional film or sheet molding method such as extrusion or casting may be used to produce a raw material containing the resin and optionally known additives.

[0071] When the porous support 12 described above 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, 10-200 μm, 10-100 μm, 10-50 μm, 15-30 μm, or 15-20 μm.

[0072] The adhesive tape 10 includes an adhesive layer 11, which, after contact with the electrolyte, absorbs the electrolyte and expands, thereby allowing the adhesive tape 10 to form an ion transport path. For example, the adhesive layer 11 can expand in the thickness direction and / or length direction upon contact with the electrolyte, thereby forming a three-dimensional structure. In the above, the "three-dimensional structure" of the adhesive tape 10 is formed through the action of the expansion force of the adhesive layer 11 of the adhesive tape 10 in contact with the electrolyte and the peeling force with the porous support 12, and may be a concept that includes all structures that allow the adhesive layer 11 to be detached from the electrode assembly.

[0073] In one example, the three-dimensional structure may include a plurality of shapes that protrude in a direction not horizontal to the longitudinal direction of the adhesive layer, preferably in a direction perpendicular to it. In the foregoing, “longitudinal direction” can mean the direction perpendicular to the thickness direction of the adhesive layer when the adhesive layer is held flat. Furthermore, “perpendicular” or “horizontal” means substantially perpendicular or horizontal to the extent that the desired effect is not impaired, and may include errors of, for example, ±10 degrees, ±5 degrees, or ±3 degrees.

[0074] As described above, the centerline average roughness Ra of the adhesive layer surface that forms a three-dimensional structure including multiple 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 of the three-dimensional structure formed by the adhesive layer of this application is adjusted within the above range, the adhesive tape can be efficiently detached from the adhesion surface inside 1c of the electrode assembly. The "centerline average roughness" means, for example, the value obtained from the following formula 1 in micrometers when a cross-section of the adhesive layer forming the three-dimensional structure is photographed, the cross-section of the three-dimensional structure is mathematically remodeled from the photographed image to obtain a roughness curve, a reference length L is extracted from the roughness curve in the direction of the average line, the direction of the average line is the x-axis and the height direction is the y-axis, and the roughness curve is displayed as y=f(x).

[0075]

number

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

[0077] By incorporating an adhesive tape that allows for the formation of ion transport paths through such changes in the three-dimensional structure, ion transport is not hindered by tape adhesion, thus preventing a reduction in battery capacity or minimizing capacity loss.

[0078] In one example, the adhesive layer 11 may include a cured product of the adhesive composition, or it may include a polymer contained in the adhesive composition in a crosslinked form. For example, the adhesive composition includes a polymer having polymerization units derived from (meth)acrylic acid monomers, monomers having polar functional groups, and crosslinkable monomers containing crosslinkable functional groups. In one example, in the case of a secondary battery manufactured by attaching an adhesive tape containing an adhesive layer formed by the adhesive composition to an electrode assembly via the adhesive layer, and inserting the electrode assembly into a battery can, the adhesive layer, upon contact with the electrolyte injected into the secondary battery, is deformed, for example, swollen or expanded, due to the presence of the polar functional groups of the monomers having polar functional groups present in the adhesive layer. In this case, the adhesive tape forms an ion transport path, and the surface of the adhesive layer comes to have a surface roughness value within a specific range. As a result, the adhesive force or peeling force between the electrode assembly and the adhesive layer decreases, and the adhesive layer detaches from the electrode assembly. Consequently, this induces isotropic volume expansion and contraction of the electrode assembly, and since the tape adhesion does not interfere with ion transport, it has the advantage of not reducing the battery capacity or minimizing capacity loss.

[0079] The adhesive composition comprises a polymer having polymerization units, and in one example, the polymer may comprise, for example, a polymer of (meth)acrylic acid monomers, monomers having polar functional groups, and crosslinkable monomers having crosslinkable functional groups.

[0080] As the (meth)acrylic acid ester monomer included in the polymerization unit of the polymer, for example, alkyl (meth)acrylate may be used, and depending on the cohesive force of the adhesive, the glass transition temperature, or the tackiness, alkyl (meth)acrylate having an alkyl group with 1 to 14 carbon atoms may be used. Examples of such monomers include, but are not limited to, one or more of the following: methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isoprofyl (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 foregoing, "(meth)acrylate" means acrylate or methacrylate, and the same applies to other terms in which "(meth)" is used.

[0082] The monomer having the polar functional group is a monomer with excellent affinity for the electrolyte, and is included as a polymerization unit in the polymer of the adhesive composition so that when the adhesive layer produced by the adhesive composition comes into contact with the electrolyte, it deforms, for example, swells, and reduces the adhesive or peeling force between the electrode assembly and the adhesive layer. Furthermore, in this application, by applying a monomer having a specific structure as the monomer having the polar functional group, the adhesive tape can form a three-dimensional structure with a specific surface roughness when in contact with the electrolyte. As a result, the adhesive tape detaches from the electrode assembly with excellent efficiency, inducing isotropic volume expansion and contraction of the electrode assembly, and the tape adhesion does not interfere with ion movement, thus having the advantage of not reducing the battery capacity or having minimal capacity loss.

[0083] In one example, the monomer having the polar functional group can be represented by the following chemical formula 1.

[0084] [ka]

[0085] In the aforementioned chemical formula 1, R1 represents hydrogen or an alkyl group having 1 to 12 carbon atoms. R2 represents an alkylene group with 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 greater than or equal to 0.

[0086] In the above 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. Examples include hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, etc. Preferably, it may be hydrogen or a methyl group, but is not limited thereto.

[0087] Furthermore, in the aforementioned chemical formula 1, R2 is an alkylene group having 1 to 6, 1 to 4, or 1 to 2 carbon atoms, and may, for example, be ethylene or propylene, but is not limited thereto.

[0088] The aforementioned 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. Examples include, but are not limited to, hydrogen, methyl group, ethyl group, propyl group, phenyl group, naphthalate group, butylphenol group, pentylphenol group, hexylphenol group, heptylphenol group, octylphenol group, or nonylphenol group.

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

[0090] In one example, the monomer represented by chemical formula 1 may be the monomer of chemical formula 2 below.

[0091] [ka]

[0092] In the aforementioned chemical formula 2, R1 and R3 are as defined above. p+q is greater than or equal to 1. p is between 0 and 100, and q is between 0 and 100.

[0093] Examples of monomers 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 acrylate nonylphenol (meth)acrylate, propoxylated acrylate nonylphenol (meth)acrylate, ethoxylated acrylate phenol (meth)acrylate, and polypropylene glycol (meth)acrylate. Preferably, methoxyethyl (meth)acrylate, methoxyethoxyethyl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, ethoxytriethylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, or polyethylene glycol methyl ether (meth)acrylate are used, but the invention is not limited thereto.

[0094] The monomer represented by chemical formula 1 or chemical formula 2 contains at least one oxygen atom, and due to the high electronegativity of the oxygen atom, the monomer becomes highly polar. Therefore, the adhesive layer containing the monomer has a high affinity for polar electrolytes and can expand upon contact with the electrolyte. On the other hand, the term "electrolyte" in the above can mean, for example, an ion-conducting medium used in secondary batteries. In one example, the electrolyte may be an electrolyte in liquid form, but is not limited thereto. In this specification, the term electrolyte may also be expressed as electrolyte.

[0095] The polymer may contain, but is not limited to, a polymer of 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, per 100 parts by weight of (meth)acrylic acid ester monomer. Furthermore, the monomer represented by Chemical Formula 1 may be present in 25 to 80 parts by weight, for example, 25 to 75 parts by weight or 30 to 70 parts by weight, per 100 parts by weight of the total monomers included in the polymer as polymerization units. If the monomer represented by Chemical Formula 1 is present in excessively low amounts, the adhesive layer may not expand sufficiently to detach from the electrode assembly upon contact with the electrolyte. Conversely, if it is present in excessive amounts, excessive gelation may occur during the polymerization reaction of the polymer, making it difficult to achieve the adhesive properties of the adhesive. Therefore, considering these points, the content of monomers having polar functional groups can be adjusted within the above range. In this specification, unless otherwise specified, "parts by weight" means a relative "weight ratio".

[0096] The crosslinkable monomer having the crosslinkable functional group may be copolymerized with the (meth)acrylic acid ester monomer or other monomers contained in the polymer, and after copolymerization, it is a monomer that can provide crosslinking sites in the main chain of the polymer that can react with a polyfunctional crosslinking agent. In the above, the crosslinkable functional group may be a hydroxyl group, a carboxyl group, an isocyanate group, a glycidyl group, or an amide group, and in some cases, it may be a photocrosslinkable functional group such as an acryloyl group or a methacryloyl group. In the case of a photocrosslinkable functional group, the crosslinkable functional group provided by the copolymerizable monomer may be introduced by reacting it with a compound having a photocrosslinkable functional group. As the crosslinkable monomer containing a hydroxyl group, for example, monomers containing a hydroxyl group such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxyethylene glycol (meth)acrylate, glycerol (meth)acrylate, or hydroxypropylene glycol (meth)acrylate may be used, or monomers mixed from one or more of these may be used, but are not limited thereto. As the carboxyl group-containing monomer, for example, (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, etc. may be used, but are not limited thereto. Furthermore, the crosslinkable monomer containing the glycidyl group may be, for example, glycidyl (meth)acrylate, epoxyalkyl (meth)acrylate, or epoxycycloalkylalkyl (meth)acrylate such as epoxycyclohexylmethyl (meth)acrylate, but is not limited thereto.The crosslinkable monomer containing the isocyanate group may be, but is 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; acryloyl monoisocyanate compounds obtained by reacting a diisocyanate compound or polyisocyanate compound with 2-hydroxyethyl (meth)acrylate; or acryloyl monoisocyanate compounds obtained by reacting a diisocyanate compound or polyisocyanate compound, a polyol compound, and 2-hydroxyethyl (meth)acrylate. As the amide group-containing monomer, for example, (meth)acrylamide, diethylacrylamide, N-vinylpyrrolidone, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N'-methyllenbisacrylamide, N,N-dimethylaminopropylacrylamide, N,N-dimethylaminopropylmethacrylamide, diacetone(meth)acrylamide, etc. may be used, but are not limited thereto. As the amino group-containing monomer, for example, aminoethyl(meth)acrylate, N,N-dimethylaminoethyl(meth)acrylate, N,N-dimethylaminopropyl(meth)acrylate, etc. may be used, but are not limited thereto. As the alkoxysilyl group-containing monomer, for example, trimethoxysilylpropyl(meth)acrylate or aryloxyethyl(meth)acrylate, etc. may be used, but are not limited thereto.

[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 per 100 parts by weight of (meth)acrylic acid ester monomer. The crosslinkable monomer may also be contained in the polymer 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, per 100 parts by weight of the total monomers contained in the polymer as polymerization units. If the crosslinkable monomer is contained in an excessively large amount, the peeling force may be too low, which may cause problems in which the adhesive layer does not easily fix the electrode assembly. If it is contained in an excessively small amount, the adhesive layer may not swell enough to detach from the electrode assembly when it comes into contact with the electrolyte. Considering these points, the content of the crosslinkable monomer can be adjusted within the above range.

[0098] The polymer may further contain other functional monomers in polymerized form, as needed, the monomer represented by the following chemical formula 3.

[0099] [ka]

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

[0101] R6~R of the above formula 10 In this definition, alkyl or alkoxy each independently means an alkyl or alkoxy having 1 to 8 carbon atoms, preferably methyl, ethyl, methoxy, ethoxy, propoxy, or butoxy.

[0102] Specific examples of the monomer of chemical 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, or N-vinylcaprolactam; styrene monomers such as styrene or methylstyrene; glycidyl(meth)acrylate; and vinyl esters of carboxylates such as caprolactone or vinyl acetate.

[0103] The polymer may be included in the composition in a form crosslinked with a polyfunctional crosslinking agent. When the polymer is included in a crosslinked form, the adhesive layer produced from the composition may have the property of expanding or swelling when it comes into contact with an electrolyte, thereby preventing electrode disconnection. Furthermore, the inclusion of the polymer in a crosslinked form ensures that the adhesive layer produced from the adhesive composition has appropriate cohesive force.

[0104] The type of polyfunctional crosslinking agent used to crosslink the polymer is not particularly limited, and an appropriate crosslinking agent may be selected from known crosslinking agents such as isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, metal chelate crosslinking agents, or photocrosslinking agents, depending on the type of crosslinkable functional group present in the polymer. Examples of isocyanate crosslinking agents include diisocyanates such as tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoborone diisocyanate, tetramethylxylene diisocyanate, and naphthalene diisocyanate, as well as reaction products of the diisocyanate with a polyol. In the above, trimethylolpropane may be used as the polyol. Examples of epoxy crosslinking agents include ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N,N,N',N'-tetraglycidylethylenediamine, or 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, bisisoprotaloyl-1-(2-methylaziridine), or tri-1-aziridinylphosphine oxide. Examples of metal chelating crosslinking agents include compounds in which a polyvalent metal is coordinated to a compound such as acetylacetone or ethyl acetoethyl. Examples of polyvalent metals include aluminum, iron, zinc, tin, titanium, antimony, magnesium, or vanadium. Examples of photocrosslinking agents include polyfunctional acrylates. In the above, one or more crosslinking agents may be used, taking into consideration the types of crosslinkable functional groups contained in the polymer.

[0105] The weight ratio of the polyfunctional crosslinking agent in the adhesive composition can be adjusted to a range that ensures, for example, the desired peeling force or the gel fraction described later. For example, the crosslinking agent may be included in an amount of 0.001 to 10 parts by weight, for example, 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 polyfunctional crosslinking agent is too low, the cohesive force of the adhesive layer may not be adequately ensured, and if it is too high, the adhesive properties may decrease, so an appropriate range can be selected taking this into consideration.

[0106] The polymer contained in the adhesive composition may be produced by applying a mixture of monomers as described above to a polymerization process such as solution polymerization, photopolymerization, bulk polymerization, suspension polymerization, or emulsion polymerization.

[0107] The polymer may have a weight-average molecular weight (Mw) of approximately 300,000 to 2,500,000, 400,000 to 2,000,000, 400,000 to 1,500,000, 400,000 to 1,000,000, 500,000 to 2,000,000, 800,000 to 1,800,000, 600,000 to 1,200,000, 700,000 to 1,400,000, or 600,000 to 800,000. In this specification, weight-average molecular weight may mean the converted value relative to standard polystyrene measured by GPC (Gel Permeation Chromatograph), and unless otherwise specified, molecular weight may mean weight-average molecular weight. If the molecular weight of the polymer is too low, the cohesive force of the 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 considering these points.

[0108] In addition to the components mentioned above, the adhesive composition may further contain a variety of additives known in the art, as needed. For example, the adhesive composition may further contain a tackifier. As the tackifier, for example, a rosin ester-based or styrene-based tackifier may be used, but is not limited thereto, and an appropriate type may be selected and used as needed. The content of the tackifier is not particularly limited and can be adjusted considering the peeling force with respect to the electrode assembly, etc. 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 adhesive composition may further contain, to the extent that it does not affect the intended effect, initiators such as thermal initiators or photoinitiators, epoxy resins, curing agents, ultraviolet stabilizers, antioxidants, colorants, reinforcing agents, fillers, defoamers, surfactants, photopolymerizable compounds such as polyfunctional acrylates, or plasticizers.

[0110] As one example, the polymer contained in the adhesive composition may be produced by photopolymerization by selecting a suitable photoinitiator that is generally well known. The photoinitiator is an organic peroxide such as benzoyl peroxide, 1,1-bis(tert-butylperoxy)-3,3,5-triethylcyclohexane, tert-butylperoxyacetate, tert-butylperoxybenzoate, tert-butylperoxy-2-ethylhexanoate, tert-butylperoxyisopropyl carbonate, di-2-ethylhexylperoxydicarbonate, diisopropylperoxydicarbonate, di-3-methoxybutylperoxydicarbonate, di-3,3,5-trimethylhexanoylperoxide, di-tert-butylperoxide, lauroyl peroxide, dicumylperoxide, methyl ether ketone peroxide; butylhydroperoxide Hydroperoxides such as ruoxide and cumyl hydroperoxide; oxidizing agents such as hydrogen peroxide, ammonium peroxide disulfate, 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 (AIBN); means of irradiation with heat, light, ultraviolet light, or high-energy wavelengths; electron transfer within the electrolyte; etc., can be applied to the photopolymerization method, but is not limited thereto.

[0111] The amount 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, per 100 parts by weight of the total monomer mixture.

[0112] The adhesive layer 11 described above can be formed, for example, by coating the porous support 12 with a coating liquid containing the polymer and a polyfunctional crosslinking agent as described above, and inducing a crosslinking reaction between the polymer and the polyfunctional crosslinking agent under appropriate conditions.

[0113] The thickness of the adhesive layer 11 can be appropriately selected according to the application, for example, the desired peeling force, and is not particularly limited. The 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 inside 1c of the electrode assembly in a secondary battery. Furthermore, in the embodiment of this application, the adhesive tape 10 has an adhesive layer 11 whose initial peeling force is not excessively high, and by including an adhesive layer 11 containing the monomer having the aforementioned polar functional group, the peeling force of the adhesive layer 11 can be adjusted to be low enough that it can be detached from the electrode assembly when the adhesive tape 10 comes into contact with the electrolyte in a secondary battery, as the adhesive layer 11 absorbs the electrolyte and expands.

[0115] In one example, the adhesive tape 10 of this application can have an initial peeling force sufficient to fix the electrode assembly and to detach from the electrode assembly when in contact with the electrolyte. If the initial peeling force of the electrode assembly is too high, the adhesive layer 11 may become difficult to detach from the electrode assembly 22 even after contact with the electrolyte. For example, the adhesive layer 11 may have a peeling force of 370 gf / 25 mm or less at room temperature, measured at a peeling speed of 5 mm / sec and a peeling angle of 180 degrees relative to glass, for example, 350 gf / 25 mm or less, 315 gf / 25 mm or less, or 312 gf / 25 mm or less. The lower limit of the peeling force of the adhesive layer 11 relative to glass is not particularly limited. For example, if it has a very low initial peeling force, the adhesive layer will lose its adhesiveness when in contact with the electrolyte, thereby preventing the electrode from breaking by detaching the adhesive tape from the electrode assembly. However, if the initial peeling force of the adhesive layer 11 is too low, the electrode assembly may dissolve before it comes into contact with the electrolyte before being placed in the can. Taking this into consideration, the lower limit of the peeling force of the adhesive layer 11 from glass can 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. If the adhesive layer 11 has a peeling force within the range described above relative to the glass, even if the adhesive layer 11 is attached to the inside 1c of the electrode assembly 1, it can exhibit an appropriate initial peeling force to detach upon contact with the electrolyte, and when the adhesive tape 10 comes into contact with the electrolyte, it can form a three-dimensional structure having a specific surface roughness.

[0116] Furthermore, in this application, the adhesive tape 10 forms a three-dimensional structure when the adhesive layer 11 absorbs the electrolyte and expands upon contact with the electrolyte, and the peeling force of the adhesive layer 11 can be adjusted to be low enough to detach from the electrode assembly, thereby allowing the adhesive layer 11 to detach from the adhesion surface inside 1c of the electrode assembly. In one example, the adhesive tape 10 may detach from the adhesion surface of the electrode assembly after contact with the electrolyte, preferably 50% or more, for example, 60% or more, 70% or more, or 80% or more of the area on which the adhesive tape 10 is attached inside 1c of the electrode assembly may detach.

[0117] The thickness of the adhesive tape 10 can be appropriately selected depending on the desired peeling force, etc., and is not particularly limited. The adhesive tape 10 may be formed to have thicknesses 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 not be achieved, and conversely, if the thickness is too thick, the thickness of the electrode assembly will increase accordingly, which may lead to greater damage to the electrode assembly due to reduced processability when inserting it into the battery case, or a decrease in capacity for the same size.

[0118] The adhesive tape 10 may further include a shaped sheet attached to the adhesive layer 11 in order to protect the adhesive layer 11 until the tape is used.

[0119] Other embodiments of this specification provide a secondary battery including the aforementioned electrode assembly and a battery case for housing the electrode assembly. In this case, the secondary battery may be embodied in a variety of forms, taking into consideration the form in which the electrode assembly is wound, the form of the 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 this specification, the electrode assembly may be of a roll type in which the cross-section perpendicular to the mandrel axis is circular.

[0121] The type of can 21 in which the electrode assembly 22 is housed is not particularly limited, and examples of types known in the art include cylindrical cans 21.

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

[0123] In the above, the type of electrolyte, which is a fluid that deforms, for example, expands, the adhesive layer 11 of the adhesive tape 10, is not particularly limited, and an electrolyte known in this art can be used depending on the type of battery. For example, if the battery is a lithium secondary battery, the electrolyte may include, for example, a non-aqueous organic solvent and a lithium salt. In the above, the lithium salt is dissolved in the organic solvent and acts as a source of lithium ions in the battery, promoting the movement of lithium ions between the positive and negative electrodes. Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiCF3SO3, LiN(CF3SO2)3, Li(CF3SO2)2N, LiC4F9SO3, LiClO4, LiAlO4, LiAlCl4, 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 supporting electrolytic salts such as LiCl, LiI, and lithium bisoxalate borate. The concentration of 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.)Furthermore, the aforementioned organic solvent acts as a medium through which ions involved in the electrochemical reaction of the battery can move. Examples of such organic solvents 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, and iodobenzoic acid. Diiodobenzene, 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 (where R is a linear, branched, or cyclic hydrocarbon group having 2 to 50 carbon atoms, and the hydrocarbon group may include a double bond, aromatic ring, or ether bond), dimethylformamide, dimethyl acetate, xylene, cyclohexane, tetrahydrofuran, 2-methyltetrahydrofuran, cyclo Examples include, but are not limited to, one or more of the following: lohexanone, 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, or mevalonolactone.

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

[0125] Traditionally, batteries with a form factor ratio of approximately 0.4 or less were used. Specifically, 18650 cells and 21700 cells were commonly used. For example, an 18650 cell has a diameter of approximately 18mm, a height of approximately 65mm, and a form factor ratio of approximately 0.277. A 21700 cell has a diameter of approximately 21mm, a height of approximately 70mm, and a form factor ratio of approximately 0.300.

[0126] A cylindrical secondary battery according to one embodiment of this specification may be a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. The numerical value representing the form factor is such that the first two digits represent the diameter of the cell, the next two digits represent the height of the cell, and the last digit 0 indicates that the cross-section of the cell is circular.

[0127] A secondary battery according to one embodiment of this 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] A secondary battery according to one embodiment of this 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] A secondary battery according to one embodiment of this 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] A secondary battery according to one embodiment of this 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] A secondary battery according to one embodiment of this 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] Other embodiments of this specification provide a secondary battery including the aforementioned electrode assembly 1 and a battery case for housing the electrode assembly 1.

[0133] Figure 11 illustrates a secondary battery 20 housed in a battery case containing 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 be provided in a columnar structure with a space formed inside. The can 21 may contain a battery assembly 1 including electrodes and a separation membrane, and an electrolyte (not shown) in its internal space. One side of the can 21 may have an open structure, and the other side may have a sealed structure. Here, one side and the other side of the can 21 refer to the ends located at the top and bottom, respectively, along the direction of gravity or the central axis of the can 21.

[0135] Can 21 may be made of a lightweight conductive metal material such as aluminum or an aluminum alloy.

[0136] The 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 interruption element.

[0137] The top cap protrudes from the very top of the cap assembly 22 and can act as an electrode terminal to electrically connect to the outside. A safety vent can release high-pressure gas if gas builds up inside due to increased pressure, and a current interruption element can interrupt the current when the battery's withstand voltage increases.

[0138] The top cap may be joined to the top of the can 21. That is, the top cap may be joined to a crimped portion located at the very 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. The gasket can increase the sealing force of the case.

[0140] The top cap may include a projection that protrudes upward in the direction of gravity, a frame that is coupled to a gasket, and a connecting portion that connects the projection and the frame.

[0141] The safety vent may be located on the underside of the top cap and connected to the end of the top cap. The safety vent may be in contact with the end of the top cap for a predetermined length, and the portion excluding the contact length may be located at a predetermined distance from the top cap.

[0142] The safety vent may be provided by being bent at least once. For example, the safety vent may have two notches in the portion that does not come into contact with the top cap. That is, the safety vent 12 may be bent by the notches, and the center of the safety vent may be recessed to form a curved central portion. The safety vent may then have a venting portion that connects the end portion that comes into contact with the top cap to the curved central portion.

[0143] The current interruption element is located below the safety vent and can be in contact with the safety vent, at least partially.

[0144] The current interruption element may include a central portion protruding in the direction of the safety vent, and a CID filter portion located outside the central portion. Thus, the cap assembly 22 can be in contact with the central portion of the current interruption element and the curved 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. The CID gasket can prevent the safety vent from making contact with a portion other than the central part of the current interruption element.

[0146] Other embodiments of this specification provide a battery pack comprising two or more of the aforementioned secondary batteries. Figure 12 is a schematic diagram showing the configuration of a battery pack according to an embodiment of the present invention.

[0147] Referring to Figure 12, the 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 houses them. The cylindrical secondary battery cell 201 is the battery cell according to the embodiment described above. For convenience of illustration, the drawings omit the depiction of components such as busbars for the electrical connection of the cylindrical secondary battery cell 201, cooling units, and external terminals.

[0148] Another embodiment of this specification provides a means of transport including the aforementioned battery pack 200. The means of transport is anything that moves or works while moving, such as luggage, people, etc., and may be a bicycle, heavy equipment, agricultural equipment, automobile, bus, airplane, etc.

[0149] The battery pack 200 can be installed in an automobile V. The automobile may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. Automobile V includes four-wheeled vehicles or two-wheeled vehicles. Figure 13 is a diagram illustrating an automobile V including the battery pack 200 of Figure 12.

[0150] Referring to Figure 13, an automobile V according to one embodiment of this specification includes a battery pack 200 according to one embodiment of this specification. The automobile V operates by receiving power from the battery pack 200 according to one embodiment of the present invention. [Examples]

[0151] This specification will be further described below by examples. However, the following examples are for illustrative purposes only and not to limit this specification.

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

[0153] To 100 parts by weight of the polymer prepared as described above, 0.3 parts by weight of trimethylolpropane tolylene diisocyanate adduct was added to an ethyl acetate solution as a polyfunctional isocyanate crosslinking agent. The mixture was then diluted to an appropriate concentration considering coating properties and uniformly mixed to produce an adhesive composition.

[0154] The adhesive composition was coated onto one side of a shaped film to a thickness of 3 μm and then dried. After transferring this to a porous support, the shaped film was removed to produce 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 mechanical direction (MD) tensile strength of 2040 kgf / cm². 2 It is a porous polyethylene (PE) support with a tensile elongation of 125% in the MD direction.

[0156] [Experimental Example 1] Manufacturing of electrode assemblies and batteries As shown in Figure 15, an electrode assembly including a negative electrode, a positive electrode, and a separator membrane was laminated, and the manufactured adhesive tape was attached to the adhesive tape position shown in Figure 15. The laminated electrode assembly was then wound up to produce a jelly roll (J / R) with a cross-sectional diameter of 17.2 mm.

[0157] A jelly roll-shaped assembly was inserted into a cylindrical can (cross-sectional diameter: 17.5 mm). Subsequently, a cabonate-based electrolyte was injected into the can, and it was sealed to complete the battery of the example (Test).

[0158] On the other hand, a battery from the above embodiment without adhesive tape attached was used as a comparative example (Ref).

[0159] The batteries of the above examples and comparative examples were charged and discharged 20 and 50 times under the following conditions, and the presence or absence of 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 To check for battery deformation after 20 and 50 charge-discharge cycles, two examples (Test) and two comparative examples (Ref) were manufactured using the same method and divided into #1 and #2. CT scans were performed using an XSCAN-8225 at 225kV and a frame rate of 3fps, and the results are shown in Figure 14.

[0161] Referring to Figure 14, the battery in the comparative example (Ref) experiences mandrel-side deformation due to electrode expansion during charging and discharging. However, in the battery in the example (Test) where adhesive tape is applied, deformation is suppressed because the separator membrane is physically reinforced by the adhesive tape. In this case, it is important to reduce deformation because mandrel (core) side deformation can damage the electrodes, reduce battery performance, and in severe cases, even cause damage to the separator membrane, potentially leading to an internal short circuit.

[0162] [Experimental Example 2] Confirmation of lithium metal deposition after disassembly. In Experimental Example 1, the battery of the Test example, which underwent 50 charge-discharge cycles, was disassembled in a fully charged state of 4.2V, and the presence or absence of lithium metal (Li metal) deposition was observed. Figure 16 shows a photograph confirming this.

[0163] Before charging, the negative electrode is black due to the carbon content, but after charging, when lithium metal intercalates, it turns yellow, and if lithium metal (Li metal) is deposited, it shows a gray color.

[0164] In the battery in the example, the area to which the adhesive tape is attached absorbs the electrolyte at the negative electrode facing the positive electrode and swells, preventing the formation of an ion exchange path. When a typical tape is attached, this obstructs the movement of lithium ions and causes lithium metal deposition in the surrounding area. On the other hand, the adhesive tape made in the manufacturing example forms an ion transfer path that allows ions to move, and thus, as confirmed in Figure 15, no lithium metal deposition occurs.

[0165] While the above has been described with reference to preferred embodiments of the present invention, those skilled in the art should understand that the present invention can be modified and altered in various ways without departing from the spirit and scope of the invention as described in the claims. [Explanation of symbols]

[0166] 1...electrode assembly 1a ···Mandrel 1b ···Outermost Outer Layer 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 Tab 2d...Cathode active material layer section 2d'...First positive electrode active material layer section 2d''...Cathode active material layer section 2e ···Positive electrode blank 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 tab 10 ···Adhesive tape 11 ···Adhesive layer 12...Porous support 20...Secondary battery 21 cans 22 ···Cap Assembly 200 ···Battery Pack 201...Cylindrical battery cell 202 ···Pack Housing 65V ··Transportation method

Claims

1. An electrode assembly comprising a positive electrode, a negative electrode, and a separation membrane provided between the positive electrode and the negative electrode, which are laminated and wound together, The aforementioned wound electrode assembly further includes an adhesive tape that is adhered to the inside of the assembly. The adhesive tape comprises a porous support and an adhesive layer provided on the porous support, the adhesive layer of which, after contact with the electrolyte, absorbs the electrolyte and expands to form an ion transport path, forming an electrode assembly.

2. The electrode assembly according to claim 1, wherein the adhesive tape is adhered to at least one of the spaces between the positive electrode and the separation membrane, and between the negative electrode and the separation membrane.

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. The electrode assembly according to claim 1, wherein the adhesive tape is adhered to at least one of the spaces between the mandrel-side end of the active material layer of the positive electrode and the separation membrane, and between the mandrel-side end of the active material layer of the negative electrode and the separation membrane.

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 according to claim 1, wherein the adhesive tape is adhered so as to cover the end of the positive electrode active material layer and the 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 are provided on the positive electrode current collector, separated in the winding direction of the electrode assembly, and Between the two or more active material layers, there is a blank area on the positive electrode current collector where the positive electrode active material layer is not provided. Includes, The electrode assembly according to claim 1, wherein the adhesive tape is adhered so as to cover the plain portion and the plain portion side end of the positive electrode active material layer.

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, in the winding direction of the electrode assembly, the mandrel-side end of the negative electrode active material layer is closer to the mandrel-side end of the positive electrode active material layer than the mandrel-side end of the separation membrane.

8. The negative electrode has an active material layer portion in which the active material layer is provided on the current collector, and In the winding direction of the electrode assembly, there are plain sections at both ends of the current collector where the active material layer is not provided. Includes, The electrode assembly according to claim 7, wherein the adhesive tape is adhered to the plain portion on the mandrel side of the negative electrode.

9. The aforementioned 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 the plain mandrel-side portion of the negative electrode facing the mandrel.

10. The aforementioned 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 the mandrel side of the plain mandrel-side portion of the negative electrode facing the mandrel.

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

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

13. An electrode assembly according to any one of claims 1 to 12, and Battery case for housing the electrode assembly Rechargeable batteries, including those mentioned above.

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 is cylindrical.

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

16. A means of transport including the battery pack of claim 15.

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