Tape for electrode including adhesive portion having pattern and secondary battery

Abstract

The present specification relates to a tape for an electrode including an adhesive layer disposed in a pattern, and a secondary battery including the same. According to the present invention, by coating the adhesive layer of the tape for an electrode in a pattern form, a path through which bubbles generated inside can escape is formed, thereby having the advantage of reducing the generation of bubbles.

Description

Technical Field

[0001] This application claims priority to and the benefit of Korean Patent Application No. 10-2022-0085796 filed in the Korean Intellectual Property Office on July 12, 2022, the entire contents of which are incorporated herein by reference.

[0002] The utility model relates to an electrode belt comprising an adhesive portion having a pattern. Background Art

[0003] In recent years, as the demand for portable electronic products such as laptop computers, camcorders, and mobile phones has continued to increase, and the development of electric vehicles, batteries for energy storage, robots, and satellites has begun in earnest, a lot of research has been conducted on secondary batteries used as driving power sources for these products.

[0004] Examples of such secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries. Among such different secondary batteries, lithium secondary batteries are widely used in the field of advanced electronic devices because lithium secondary batteries can be freely charged / discharged due to almost no memory effect compared to nickel-based secondary batteries, have very low self-discharge rate, high operating voltage, and high energy density per unit weight.

[0005] Generally, a lithium secondary battery is configured by stacking or winding an electrode assembly consisting of a positive electrode, a negative electrode, and a separator interposed therebetween, embedding the stacked or wound electrode assembly in a metal can or laminate case, and injecting or impregnating an electrolyte solution therein.

[0006] The electrode assembly with a positive electrode / separator / negative electrode structure constituting a secondary battery is mainly divided into a jelly-roll type (winding type) electrode assembly and a stacked type (stacked type) electrode assembly according to its structure. The jelly-roll type electrode assembly has a structure in which a separator is interposed between a long sheet-like positive electrode coated with an active material and a negative electrode, which is then wound, while the stacked type electrode assembly has a structure in which a plurality of positive electrodes and negative electrodes having a predetermined size are sequentially stacked with a separator interposed therebetween. Among them, the advantages of the jelly-roll type electrode assembly are that it is easy to manufacture, has a high energy density per unit weight and is structurally stable.

[0007] The jelly roll type electrode assembly is composed of a positive electrode, a negative electrode and a separator, and the positive electrode and the negative electrode are each formed by coating an electrode active material on a metal foil. Depending on the design, there is a coated portion coated with an electrode active material and an uncoated portion where the foil is exposed, and an electrode tape may be applied to the positive electrode or the negative electrode.

[0008] In this case, since the adhesive layer of the electrode tape and the metal film as the adherend have a strong interaction, bubbles may be generated during attachment. In addition, the generated bubbles are difficult to escape due to the strong interaction, and the generated bubbles increase the outer diameter of the jelly roll type electrode assembly, causing can insertion defects and hindering the structural stability of the secondary battery.

[0009] Therefore, there is a need for a method for improving the structural stability of secondary batteries. Utility Model Content

[0010] Technical issues

[0011] In the present specification, there are provided a tape for an electrode including an adhesive part having a pattern and a secondary battery including the same.

[0012] Technical Solution

[0013] An exemplary embodiment of the utility model provides a tape for an electrode, comprising: a base film; and an adhesive portion disposed on one surface of the base film, wherein the adhesive portion comprises an adhesive layer and a gravure region, wherein the gravure region is disposed in a pattern, and wherein the pattern is disposed on the entire surface of the adhesive portion.

[0014] An exemplary embodiment of the present invention provides a secondary battery including an electrode assembly having a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, and the electrode tape.

[0015] Beneficial Effects

[0016] The utility model has the effect of reducing the generation of bubbles by forming a path through which bubbles generated inside can escape by coating the adhesive layer of the electrode tape in a pattern form. In addition, since bubbles can be easily removed without a roller, the utility model can be used in the existing process without an additional process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 and Figure 2 A cross section of a tape for an electrode according to an exemplary embodiment of the present invention is shown.

[0018] Figure 3 Experimental results according to Example 1 and Comparative Example 1 are shown.

[0019] [Explanation of Reference Numerals]

[0020] 10: Base film

[0021] 20: Adhesive part

[0022] 21: Adhesive layer

[0023] 22: Gravure area DETAILED DESCRIPTION

[0024] Hereinafter, the present specification will be described in more detail.

[0025] In the present specification, unless explicitly described to the contrary, when a part is referred to as “comprising” a certain component, it means that the part may further include other components, without excluding the other components.

[0026] Throughout the specification, when a member is referred to as being 'on' another member, the member may be in direct contact with the other member, or intervening members may also be present.

[0027] In this specification, when a part is referred to as being connected to another part, this includes not only a case where they are directly connected but also a case where they are indirectly connected with another element interposed therebetween.

[0028] Hereinafter, the preferred exemplary embodiments of the utility model will be described in detail with reference to the accompanying drawings. However, it should be understood that the embodiments of the utility model can be modified in various forms, and the scope of the utility model is not limited to the embodiments described below. In the detailed description of the operating principle of the preferred exemplary embodiments of the utility model, when it is determined that the detailed description of the related known functions or configurations may unnecessarily obscure the subject matter of the utility model, the detailed description will be omitted. In addition, in all the drawings, the same reference numerals are used for parts with similar functions and operations.

[0029] An exemplary embodiment of the present invention provides an electrode tape, comprising: a base film; and an adhesive portion disposed on one surface of the base film, wherein the adhesive portion comprises an adhesive layer and a gravure region, wherein the gravure region is disposed in a pattern, and wherein the pattern is disposed on the entire surface of the adhesive portion.

[0030] Generally, a jelly roll type electrode assembly includes a positive electrode, a negative electrode and a separator, and each of the positive electrode and the negative electrode is formed by coating a metal foil with an electrode active material. Depending on the design, there is a coated portion coated with an electrode active material and an uncoated portion where the electrode active material is not coated and thus the metal foil is exposed, and an electrode tape may be applied to the uncoated portion.

[0031] In this case, since the adhesive layer of the electrode tape and the metal foil as the adherend have a strong interaction, bubbles are easily generated during attachment. In addition, the bubbles are difficult to escape due to the strong interaction between the adhesive layer and the metal foil, and the generated bubbles increase the outer diameter of the electrode assembly, causing defects during can insertion and hindering the structural stability of the secondary battery.

[0032] Therefore, in order to minimize the generation of bubbles while using the existing tape for an electrode, a roller should inevitably be introduced in the tape attaching process, and adding such a process may cause problems such as increased cost and increased manufacturing time due to equipment modification.

[0033] On the other hand, the utility model has the feature of reducing the generation of bubbles by forming a path through which bubbles generated inside can escape by coating the adhesive layer of the electrode tape in a pattern form. In addition, since bubbles can be easily removed without a roller, the utility model can be used in the existing process without an additional process.

[0034] In an exemplary embodiment of the present invention, a tape for an electrode includes a base film; and an adhesive portion provided on one surface of the base film.

[0035] In an exemplary embodiment of the present invention, the base film may include one or more films selected from acrylic films, polyolefin films, polyamide films, polycarbonate films, polyurethane films, cellulose acetate films, and polyester films, but is not limited thereto.

[0036] When a polyester film is used as the base film, one or more films selected from polyethylene terephthalate film, polyethylene naphthalate film and polybutylene terephthalate film can be used, and when a cellulose-based base layer is used as the base film 10, for example, as a base film containing cellulose acetate resin or cellulose alkylate resin, a base film manufactured by applying a mixture containing the resin to an extrusion or casting process can be used. As the cellulose alkylate, for example, cellulose acetate propionate, cellulose acetate butyrate, etc. can be used.

[0037] The method for manufacturing the base film is not particularly limited, and for example, a common film or sheet forming method such as extruding or casting a raw material containing a resin can be used. In this case, if necessary, a known additive can be added to the raw material containing the resin.

[0038] The thickness t1 of the base film as described above is not particularly limited, and may be, for example, about 10 to 200 μm, about 10 to 100 μm, about 10 to 50 μm, about 15 to 30 μm, or about 15 to 20 μm.

[0039] The base film is not formed with holes or patterns. Since the tape is manufactured in roll form by a roll-to-roll process, or attached to the battery by a roll-to-roll process, tension is applied to the tape during this process. Therefore, when the base film is formed with holes or patterns, problems such as rupture, stretching and extension of the pattern / holes of the film may occur. In addition, as described above, when the base film does not include holes or patterns and only includes a patterned adhesive layer, the physical strength of the electrode tape is increased and stable quality can be maintained.

[0040] In the present invention, the gravure region means a region having a thickness shallower than that of the adhesive portion because the adhesive layer is not provided on the adhesive portion or the adhesive layer is recessed by a certain depth from the surface of the adhesive portion in the direction of the base film.

[0041] In an exemplary embodiment of the present invention, the adhesive portion includes an adhesive layer and a concave region.

[0042] The intaglio region may be provided in a pattern, and the pattern may be provided on the entire surface of the adhesive portion. That is, the pattern may be provided on the entire surface of the adhesive portion, rather than being provided only in a specific region of the adhesive portion.

[0043] In an exemplary embodiment of the present invention, a pattern may be formed on a surface of the adhesive part opposite to a surface on which the base film is provided.

[0044] Figure 1 and Figure 2 A cross section of a tape for an electrode according to an exemplary embodiment of the present invention is shown.

[0045] Specifically, forming the gravure region in a pattern may mean that the adhesive layer itself forms a pattern from the adhesive layer and the gravure region formed on one surface of the base film.

[0046] In an exemplary embodiment of the present invention, the concave region may be a region of the adhesive portion in which the adhesive layer is not disposed.

[0047] Figure 1 The cross section of the electrode tape is schematically shown when the adhesive portion 20 includes an adhesive layer 21 and an area (intaglio area) 22 without an adhesive layer. Specifically, as Figure 1 As shown, regions provided with adhesive layer 21 and regions without adhesive layer (intaglio regions) 22 are positioned at regular intervals or in a regular manner on one surface of base film 10 so that adhesive layer 21 itself forms a specific pattern.

[0048] In another exemplary embodiment, the gravure region may be a region having a thickness shallower than that of the adhesive part because the adhesive layer is recessed by a predetermined depth from the surface of the adhesive part in the direction of the base film.

[0049] Figure 2 The cross section of the tape for an electrode is schematically shown when the adhesive portion 20 includes an adhesive layer 21 and a concave region 22 in which the adhesive layer is recessed by a predetermined depth from the surface of the adhesive portion in the direction of the base film. Figure 2 As shown, the concave region 22 is formed on the adhesive layer 21 disposed on one surface of the base film 10, and the concave region 22 is formed in a specific pattern.

[0050] In addition, the pattern is positioned on the entire surface of the adhesive portion in the electrode tape. That is, the adhesive portion 20 including the adhesive layer 21 and the concave region 22 may be provided on the entire surface of one surface of the base film 10, and the pattern may be provided on the entire surface of the adhesive portion 20. That is, the pattern is not provided only at a specific position on the adhesive portion.

[0051] In an exemplary embodiment of the present invention, the pattern may be an intaglio pattern including an intaglio area 22 having an intaglio shape.

[0052] The gravure pattern may be a closed graphic pattern, a linear pattern, or a mixed pattern of a closed graphic pattern and a linear pattern. The lines of the gravure pattern may be straight lines, zigzag lines, wavy patterns, etc. In one example, the gravure pattern may be a lattice pattern or an S-shaped pattern, but is not limited thereto.

[0053] The closed figure of the intaglio pattern may be a circle. When the closed figure of the intaglio pattern is a circle, the intaglio region may be cylindrical or hemispherical. However, the present invention is not limited thereto, and other shapes that allow bubbles to escape easily may be applied.

[0054] Using the above-mentioned pattern shapes, the pattern may be formed in a stripe shape, a wave shape, or a dot shape, but is not limited thereto, and a pattern shape used in the art may be adopted as appropriate.

[0055] In an exemplary embodiment of the utility model, the average width w2 of the gravure region can be 0.1mm or more and 5mm or less, and preferably 0.4mm or more and 3mm or less. In an example, the average width can be 0.5mm or more and 3mm or less, or 0.5mm or more and 2mm or less. If the average width of the gravure region is less than the above range, there is a problem that the suitable width for the bubble escape cannot be ensured, and the pattern forming is difficult. In addition, even if a pattern is formed, there is a problem that it is not easy to remove bubbles, because the viscoelastic material contained in the adhesive layer will then fill the pattern. On the other hand, if the average width of the gravure region exceeds the above range, there is a problem that the adhesive force cannot be fully expressed, and the outer diameter increases when attached to the electrode assembly. When the average width of the gravure region meets the above range, the bubbles when the tape is attached can be easily removed, and the adhesive force of the tape is fully ensured, thereby effectively preventing defects during tank insertion by preventing the outer diameter of the electrode assembly from increasing when attached to the electrode assembly.

[0056] The upper limit of the average width of the intaglio region may be 5 mm, 4 mm, 3.5 mm, 3 mm, 2.5 mm, or 2 mm, and the lower limit may be 0.1 mm, 0.4 mm, or 0.5 mm.

[0057] In an exemplary embodiment of the present invention, the adhesive portion includes a relief region. Specifically, a portion of the adhesive layer in which no intaglio region is located, that is, a region having the same thickness as that of the adhesive portion is defined as a relief region.

[0058] In an exemplary embodiment of the present invention, the average width w1 of the relief region may be 0.1 mm or more and 5 mm or less, specifically 1 mm or more and 4 mm or less, and more specifically 1 mm or more and 3.5 mm or less. If the average width of the relief region satisfies the above range, bubbles can be easily removed when the tape is attached, and the adhesive force of the tape is sufficiently ensured, thereby effectively preventing defects during can insertion by preventing the outer diameter of the electrode assembly from increasing when attached to the electrode assembly.

[0059] The upper limit of the average width of the relief area may be 5 mm, 4 mm, 3.5 mm, 3 mm, or 2.5 mm, and the lower limit may be 0.1 mm, 0.5 mm, 0.8 mm, or 1 mm.

[0060] The ratio of the average width w2 of the concave region to the average width w1 of the relief region (w2:w1) is 1:1 to 1:4, 1:1.15 to 1:1.35, or 1:2 to 1.3. When the ratio of the average width of the concave region to the average width of the relief region (w2:w1) satisfies the above range, bubbles can be easily removed when attaching the tape, and the adhesive force of the tape is sufficiently ensured.

[0061] In an exemplary embodiment of the utility model, the gravure region 22 of the pattern may occupy 1% or more and 50% or less based on the total area of ​​one surface of the base film provided with the adhesive portion. Specifically, the gravure region may occupy 10% or more and 30% or less, and more specifically, 20% or more and 30% or less. When the above range is met, bubbles when attaching the tape can be easily removed, and the adhesive force of the tape is fully ensured.

[0062] In an exemplary embodiment of the present invention, the average depth d of the gravure region may be 10% or more, 20% or more, 30% or more, or 40% or more, preferably 50% or more of the thickness t2 of the adhesive portion 20. In one example, the average depth d of the gravure region may be 60% or more, 70% or more, 80% or more, 90% or more, or 100% of the thickness t2 of the adhesive portion. The depth of the gravure pattern may be equal to the maximum thickness t2 of the adhesive portion 20, and in this case, the gravure region 22 in the gravure pattern may mean Figure 1 The area in which the adhesive layer is not provided.

[0063] When the depth of the gravure pattern satisfies the above range, there is an effect that bubbles formed when the electrode tape is attached to the metal foil can escape more easily. If the depth of the gravure pattern is less than the above range, there is a problem that the pattern collapses due to the fluidity of the adhesive and the retention of the pattern decreases.

[0064] In an exemplary embodiment of the utility model, the adhesive layer may be provided at 50% or more, 60% or more, or 70% or more based on the total area of ​​one surface of the base film, or may be provided on the entire surface of one surface of the base film. That is, when the depth d of the gravure region is formed to be less than 100% of the thickness t2 of the adhesive portion, the adhesive layer may be provided on the entire surface of one surface of the base film.

[0065] In an exemplary embodiment of the present invention, the pattern may be completely formed on one surface of the adhesive layer or one surface of the base film. That is, the adhesive part 20 including the adhesive layer 21 and the concave region 22 may be in the form of being disposed on the entire surface of one surface of the base film.

[0066] The adhesive layer may include an adhesive composition. Specifically, the adhesive layer may include a cured product of the adhesive composition, and may include a polymer included in the adhesive composition in a cross-linked form.

[0067] The adhesive composition may include one or more selected from acrylic resins, urethane-based resins, epoxy-based resins, silicone-based resins, and rubber-based resins. However, the present invention is not limited thereto, and adhesive resins used in the art may be used as appropriate.

[0068] In one example, the adhesive layer may include an acrylic resin, for example, an acrylic polymer cross-linked by a multifunctional cross-linking agent.

[0069] As the acrylic polymer, a polymer having a weight average molecular weight (Mw) of 400,000 or more can be used. The weight average molecular weight refers to a conversion value relative to standard polystyrene measured by gel permeation chromatography (GPC). Unless otherwise clearly defined in this specification, the term "molecular weight" means the weight average molecular weight. The upper limit of the molecular weight of the acrylic polymer is not particularly limited, and, for example, can be controlled within the range of 2.5 million or less.

[0070] Acrylic polymers may include (meth) acrylate monomers in polymerized form and copolymerizable monomers with crosslinkable functional groups. As (meth) acrylate monomers included in the polymer, for example, (meth) alkyl acrylates may be used, and in view of the cohesive force, glass transition temperature or adhesion of the adhesive, (meth) alkyl acrylates with an alkyl group containing 1 to 14 carbon atoms may be used. Examples of such monomers may include one or two or more of the following: methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, tert-butyl (meth) acrylate, sec-butyl (meth) acrylate, amyl (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, but are not limited thereto.

[0071] The copolymerizable monomer with crosslinkable functional group is such a monomer: it can be copolymerized with the (meth) acrylate monomer or other monomer contained in the polymer, and can provide a crosslinking point capable of reacting with a multifunctional crosslinking agent for the main chain of the polymer after copolymerization. In the above, the crosslinkable functional group can be a hydroxyl group, a carboxyl group, an isocyanate group, a glycidyl group, an amide group, etc., and in some cases, it can be a photo-crosslinkable functional group, such as an acryloyl group or a methacryloyl group. In the case of a photo-crosslinkable functional group, it can be introduced by reacting a compound with a photo-crosslinkable functional group with a crosslinkable functional group provided by a copolymerizable monomer. In the field of producing adhesives, a variety of copolymerizable monomers are known, and the copolymerizable monomers can be used according to the desired functional group. Examples of such monomers may include monomers having a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 2-hydroxyethylene glycol (meth)acrylate, or 2-hydroxypropylene glycol (meth)acrylate; monomers having a carboxyl group, such as (meth)acrylic acid, 2-(meth)acryloyloxyacetic acid, 3-(meth)acryloyloxypropionic acid, 4-(meth)acryloyloxybutyric acid, acrylic acid dimer, itaconic acid, maleic acid, and maleic anhydride; glycidyl (meth)acrylate, (meth)acrylamide, N-vinyl pyrrolidone, or N-vinyl caprolactam, etc., but are not limited thereto. One or two or more of these monomers may be included in the polymer.

[0072] If necessary, the acrylic polymer may further include other functional comonomers in a polymerized form, and examples thereof may include a monomer represented by the following Chemical Formula 1.

[0073] [Chemical formula 1]

[0074]

[0075] In Chemical Formula 1,

[0076] R1 to R3 each independently represent hydrogen or an alkyl group, R4 represents a cyano group, an unsubstituted or alkyl-substituted phenyl group, an acetoxy group or COR5, wherein R5 represents an amino group or an unsubstituted or alkyl- or alkoxyalkyl-substituted glycidyloxy group.

[0077] In the definitions of R1 to R5 in Chemical Formula 1, the alkyl group or alkoxy group means an alkyl group or alkoxy group having 1 to 8 carbon atoms, and is preferably a methyl group, an ethyl group, a methoxy group, an ethoxy group, a propoxy group or a butoxy group.

[0078] Specific examples of the monomer of Chemical Formula 1 may include (meth)acrylonitrile, N-methyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, styrene, methylstyrene, vinyl esters of carboxylic acids such as vinyl acetate, and the like, but are not limited thereto.

[0079] The acrylic polymer can be produced by, for example, solution polymerization, photopolymerization, bulk polymerization, suspension polymerization, emulsion polymerization, or the like.

[0080] The type of multifunctional crosslinking agent for crosslinking the acrylic polymer in the adhesive layer is not particularly limited. For example, in known crosslinking agents such as isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, metal chelate crosslinking agents or photocrosslinking agents, suitable crosslinking agents can be selected according to the type of crosslinkable functional groups present in the polymer. Examples of isocyanate crosslinking agents can include diisocyanates, such as toluene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tetramethylxylene diisocyanate or naphthalene diisocyanate, reaction products of diisocyanates and polyols, etc., and trimethylolpropane etc. can be used as polyols. As epoxy crosslinking agents, ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N,N,N',N'-tetraglycidyl ethylenediamine, glycerol diglycidyl ether, etc. can be used. Examples of aziridine crosslinking agents may include N, N'-toluene-2,4-bis(1-aziridine carboxamide), N, N'-diphenylmethane-4,4'-bis(1-aziridine carboxamide), triethylene melamine, bisisoprotaloyl-1-(2-methylaziridine) or tri-1-aziridine phosphine oxide, etc. Examples of metal chelate crosslinking agents may include compounds in which a polyvalent metal is coordinated with a compound such as acetylacetone or ethyl acetylacetate, and examples of polyvalent metals may include aluminum, iron, zinc, tin, titanium, antimony, magnesium, vanadium, etc. As a photocrosslinking agent, multifunctional acrylates, etc. may be used. Considering the type of crosslinkable functional groups contained in the polymer, one or two or more crosslinking agents may be used.

[0081] The adhesive layer as described above can be formed, for example, by coating a coating solution in which an acrylic polymer and a multifunctional crosslinking agent are mixed, and initiating a crosslinking reaction between the polymer and the multifunctional crosslinking agent under appropriate conditions.

[0082] The adhesive layer may further include one or more additives selected from the group consisting of coupling agents, tackifiers, epoxy resins, UV stabilizers, antioxidants, colorants, reinforcing agents, fillers, defoamers, surfactants, and plasticizers within a range not affecting the desired effects.

[0083] The thickness of the adhesive layer may be, 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, or 5 μm to 7 μm. However, the thickness of the adhesive layer may be appropriately selected according to the intended use and is not limited to the above range.

[0084] In an exemplary embodiment of the present invention, the tape for an electrode may further include a release film disposed on one surface of the adhesive layer to protect the adhesive layer until the tape for an electrode is used.

[0085] Specifically, a release film may be additionally provided on a surface opposite to one surface of the adhesive layer in contact with the base film.

[0086] In an exemplary embodiment of the present invention, the release film may be a hydrophobic film. The release film is a layer having a very thin thickness for protecting the adhesive layer, and refers to a transparent layer attached to one surface of the adhesive layer, and a film having excellent mechanical strength, thermal stability, moisture barrier properties, isotropic properties, etc. may be used. For example, a resin film based on acetate (e.g., triacetyl cellulose (TAC)), polyester, polyether sulfone, polycarbonate, polyamide, polyimide, polyolefin, cycloolefin, polyurethane, and acrylic may be used, but the present invention is not limited thereto, as long as the film is a commercially available silicon-treated release film.

[0087] The release film can be completely removed when applied to a secondary battery.

[0088] In an exemplary embodiment of the present invention, when the electrode tape is attached so that the adhesive portion is positioned on the metal foil, the bubbles formed between the metal foil and the electrode tape may occupy an area less than 1% based on the total area of ​​the electrode tape. Specifically, the area may be 0% or more and 0.5% or less, and the smaller the area, the more advantageous it is.

[0089] In an exemplary embodiment of the present invention, when the tape for an electrode is attached such that the adhesive portion is positioned on the metal foil, there may be no air bubbles between the metal foil and the adhesive layer.

[0090] The type of the metal foil is not limited, and a type generally used in the art may be used as appropriate. For example, the metal foil may be a copper foil.

[0091] An exemplary embodiment of the present invention provides a secondary battery including an electrode assembly having a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; and a tape for an electrode.

[0092] When a general tape for an electrode is applied to a secondary battery, there is a problem that bubbles are generated when the tape is attached to a metal film, and even if a roller process is introduced to remove the bubbles, the pores cannot be completely removed, and small and hard pores remain. In addition, the introduction of the roller process leads to problems such as increased costs and increased manufacturing time due to equipment modification.

[0093] On the other hand, when the electrode tape according to an exemplary embodiment of the utility model is applied to a secondary battery, the adhesive layer is coated in a pattern to form a path through which bubbles generated inside can escape, thereby reducing the generation of bubbles. In addition, since most of the pores are removed without introducing a roller process, the stability and process advantages of the secondary battery can be promoted at the same time.

[0094] In an exemplary embodiment of the utility model, the electrode tape can be attached to the uncoated portion of the electrode. Specifically, the tape can be attached to the uncoated portion of the electrode, to the stepped portion between the coated portion of the electrode provided with the electrode active material layer and the uncoated portion of the electrode, or to the electrode tab positioned on the uncoated portion of the electrode, or to the opposite surface of the electrode facing it. In addition, the tape can be attached to other areas above the above-mentioned areas, and in addition to the above-mentioned parts, can be attached to the parts where the tape is needed, while minimizing bubbles.

[0095] In an exemplary embodiment of the present invention, the electrode tape may be attached to surround the peripheral surface of the electrode assembly, including a facing portion in which the outermost end portion of the peripheral surface is positioned. In this case, the upper and lower ends of the peripheral surface of the electrode assembly may be attached so that the electrode assembly is exposed as is.

[0096] The electrode assembly may include an electrode laminate including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode.

[0097] The electrode laminate may be formed into a jelly roll type electrode assembly by winding the positive electrode, the negative electrode and the separator together, or may be formed into a stacked type electrode assembly or a stacked and folded type electrode assembly. The separator is used to separate and electrically insulate the positive electrode from the negative electrode.

[0098] An electrode laminate according to an exemplary embodiment of the present invention may include an electrode including an electrode current collector.

[0099] A plurality of electrodes may be provided, and a separator may be provided between the plurality of electrodes.

[0100] The electrode can be a positive electrode or a negative electrode.

[0101] The electrode includes an electrode current collector, an electrode coating portion on which an electrode active material layer is disposed, and an electrode uncoated portion on which an electrode active material layer is not disposed. Specifically, the electrode coating portion may be formed by coating an electrode active material on one surface or both surfaces of the electrode current collector, and the electrode current collector may be exposed on the electrode uncoated portion not coated with the electrode active material.

[0102] On one surface of the electrode current collector, one or two or more electrode uncoated portions and one or two or more electrode coated portions may be provided. That is, the area where the electrode uncoated portion and the electrode coated portion are provided is not specified but may vary according to the configuration of the battery.

[0103] The tape for an electrode according to an exemplary embodiment of the present invention may be attached to an electrode uncoated portion.

[0104] The positive electrode may include a positive electrode current collector and a positive electrode active material coated on the positive electrode current collector. Here, the positive electrode current collector may be composed of, for example, a foil made of aluminum (Al). In this case, the positive electrode active material may be composed of, for example, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or a composite or mixture containing one or more thereof.

[0105] The negative electrode may include a negative electrode current collector and a negative electrode active material coated on the negative electrode current collector. Here, the negative electrode current collector may be composed of, for example, a foil made of copper (Cu) or nickel (Ni). In this case, the negative electrode active material may be made of a material including, for example, artificial graphite. In addition, the negative electrode active material may be composed of, for example, lithium metal, lithium alloy, carbon, petroleum coke, activated carbon, graphite, silicon compound, tin compound, titanium compound or an alloy thereof.

[0106] The separator separates and electrically insulates the positive electrode from the negative electrode. Here, the positive electrode and the negative electrode may be wound together with the separator to form a jelly roll type electrode assembly, or may be formed into a stacked type electrode assembly or a stacked and folded type electrode assembly.

[0107] The separator is made of an insulating material and can be alternately laminated with the positive electrode and the negative electrode. Here, the separator can be positioned between the positive electrode and the negative electrode and on the outer surface of the positive electrode and the negative electrode.

[0108] Any separator may be used without particular limitation as long as it is generally used in secondary batteries, and in particular, a separator having high moisture retention capacity for an electrolyte solution and low resistance to movement of ions of the electrolyte solution may be preferably used.

[0109] In addition, separator can be made of flexible material.In this case, separator can be formed by, for example, a resin film based on polyolefin with microporosity, such as polyethylene and polypropylene.As another example, porous polymer film can be used, for example, a porous polymer film made by a polymer based on polyolefin (such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer), or it has a laminated structure of two or more layers.In addition, typical porous nonwoven fabrics can be used, for example, a nonwoven fabric formed by high melting point glass fiber, polyethylene terephthalate fiber, etc. In addition, a coated separator comprising a ceramic component or a polymer material can be used to ensure heat resistance or mechanical strength, and a separator with a single layer or multilayer structure can be selectively used.

[0110] The tape for the electrode may be attached to the outer peripheral surface of the electrode assembly via the adhesive layer.The electrode assembly may be wound into a jelly roll shape.

[0111] The separator or the electrode uncoated portion may be positioned on the outer peripheral surface of the electrode assembly.

[0112] Utility Model Implementation Method

[0113] Hereinafter, embodiments will be described in detail to specifically describe this specification. However, embodiments according to this specification can be modified in other forms, and the scope of the present application is not interpreted as being limited to the following embodiments. Embodiments of the present application are provided to more completely explain this specification to those skilled in the art.

[0114] <Example>

[0115] Example 1

[0116] A monomer mixture consisting of 98 parts by weight of n-butyl acrylate (n-BA) and 2 parts by weight of hydroxybutyl acrylate (HBA) and 0.02 parts by weight of n-dodecyl mercaptan as a chain transfer agent are placed in a 1000cc reactor equipped with a cooling device so that nitrogen is refluxed and the temperature can be easily controlled, and 150 parts by weight of ethyl acetate (EAc) as a solvent are placed in the reactor. Then, after purging with nitrogen for 60 minutes at 60°C to remove oxygen, the reactor temperature is maintained at 60°C. After homogenizing the mixture, 0.04 parts by weight of azobisisobutyronitrile (AIBN) as a reaction initiator is placed in the reactor. The mixture is reacted for 8 hours to manufacture a polymer having a weight average molecular weight of 800,000. In the above, parts by weight means % by weight.

[0117] Into the ethyl acetate solution, 0.3 parts by weight of toluene diisocyanate adduct of trimethylolpropane as a multifunctional isocyanate-based crosslinking agent was put based on 100 parts by weight of the polymer produced above, and then diluted to a suitable concentration in consideration of coating properties and uniformly mixed.

[0118] The adhesive composition manufactured as described above was coated on one surface of a polyethylene terephthalate (PET) film (thickness: 20 μm) in a lattice pattern using an embossed release paper, and dried to manufacture an electrode tape having an adhesive portion having a thickness of 5 μm. In this case, in the lattice pattern, the average width of the relief region was 1 mm, the average width of the concave region was 0.5 mm, and the average depth of the concave region was 3 μm.

[0119] After cutting the tape for the electrode into a size of 20 mm×100 mm, the tape was attached to the copper foil.

[0120] Example 2

[0121] The adhesive composition prepared in Example 1 was coated on one surface of a PET film (thickness: 20 μm) in an S-shaped pattern and dried, so that a tape for an electrode having an adhesive portion having a thickness of 5 μm was prepared. In this case, in the S-shaped pattern, the average width of the relief region was 3 mm, the average width of the concave region was 1 mm, and the average depth of the concave region was 5 μm.

[0122] After cutting the tape for the electrode into a size of 20 mm×100 mm, the tape was attached to the copper foil.

[0123] Comparative Example 1

[0124] The tape for the electrode was attached to the copper foil in the same manner as in Example 1, except that the adhesive composition produced in Example 1 was coated on one surface of a PET film (thickness: 20 μm) without a pattern.

[0125] <Experimental example>

[0126] In Example 1, Example 2, and Comparative Example 1, it was determined whether voids were formed between the attached tape and the copper foil, and then after pressing was repeated twice with a 2 kg roller, it was determined whether the voids were removed. Figure 3 The results shown were evaluated according to the following criteria and are recorded in Table 1.

[0127] [Evaluation criteria]

[0128] Confirm whether the area of ​​pores with an average diameter of 2 mm or more satisfies the following value.

[0129] Porosity area 10% or more: X

[0130] Pore ​​area 1% or more and less than 10%: △

[0131] Pore ​​area less than 1%: O

[0132] [Table 1]

[0133]

[0134] In Table 1 and Figure 3 In Examples 1 and 2, a patterned adhesive layer was used, and it could be confirmed that no voids were formed when the tape was attached to the copper foil, and there was no difference before and after extrusion.

[0135] On the other hand, in Comparative Example 1, it can be confirmed that when the tape is attached to the copper foil, the area of ​​the pores formed between the adhesive layer and the foil is very wide, and the area of ​​the pores is reduced after being squeezed twice with a roller, but the pores are not completely removed, but hard holes are formed. When hard holes are formed as in Comparative Example 1, the outer diameter of the electrode assembly may increase, resulting in a can insertion defect.

[0136] Although the present invention has been described with reference to the preferred embodiments, those skilled in the art will appreciate that various modifications and changes may be made to the present invention without departing from the technical spirit and scope of the present invention.

Claims

1. An electrode belt, comprising: Basic membrane; and an adhesive portion provided on one surface of the base film, Characterized in that the adhesive portion comprises an adhesive layer and a gravure region, wherein the intaglio regions are arranged in a pattern, and wherein the pattern is provided on the entire surface of the adhesive portion.

2. The electrode tape according to claim 1, characterized in that: The intaglio region is a region of the adhesive portion in which an adhesive layer is not provided.

3. The electrode tape according to claim 1, characterized in that: Since the adhesive layer is recessed by a predetermined depth from the surface of the adhesive portion in the direction of the base film, the concave region is a region having a thickness shallower than that of the adhesive portion.

4. The electrode tape according to claim 1, characterized in that: The pattern is a closed graphic pattern, a linear pattern, or a mixed pattern of a closed graphic pattern and a linear pattern.

5. The electrode tape according to claim 1, characterized in that: The average width of the intaglio region is 0.4 mm or more and 3 mm or less.

6. The electrode tape according to claim 1, characterized in that: The adhesive portion includes a relief region, and wherein the average width of the relief region is 1 mm or more and 4 mm or less.

7. The electrode tape according to claim 6, characterized in that: The ratio of the average width of the intaglio region to the average width of the relief region is 1:1 to 1:

4.

8. The electrode tape according to claim 1, characterized in that: The average depth of the concave region is 50% or more of the thickness of the adhesive portion.

9. The electrode tape according to claim 1, characterized in that: The base film includes one or more films selected from the group consisting of acrylic films, polyolefin films, polyamide films, polycarbonate films, polyurethane films, cellulose acetate films, and polyester films.

10. The electrode tape according to claim 1, characterized in that: When the tape for an electrode is attached so that the adhesive portion is positioned on the metal foil, bubbles formed between the metal foil and the tape for an electrode occupy an area less than 1% based on a total area of ​​the tape for an electrode.

11. A secondary battery, characterized in that: The secondary battery comprises: An electrode assembly comprising a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, and The electrode tape according to any one of claims 1 to 10.

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