Tape for electrode tabs, its use, application method, secondary battery, battery module, battery pack, and electrical device

Abstract

The present application relates to a tape for electrode tabs, comprising a base layer and an adhesive layer, the adhesive layer extending in a width direction from one side edge of the tape, having a thick region and a thin region, the thick region being distributed along one side edge of the tape, the adhesive layer thickness of the thick region being greater than that of the thin region, and the ratio of the area of ​​the thin region to the area of ​​the thick region being 1:0.02-0.25, preferably 1:0.025-0.18, more preferably 1:0.0275-0.125. The tape encases the edge of the tab, thereby fundamentally preventing contact between the tab and the battery cell body, and preventing interference from the top cover when the battery cell is inserted into a case, thereby improving the safety performance of the secondary battery.

Description

[Technical Field]

[0001] The present application relates to the technical field of lithium batteries, and more particularly to an electrode tab tape and its use, application method, secondary battery, battery module, battery pack and electric device. [Background technology]

[0002] In recent years, the application range of secondary batteries has become increasingly broad, and lithium-ion batteries are widely used in various fields, such as storage power systems for hydroelectric, thermal, wind, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. As secondary batteries have developed significantly, higher requirements are being placed on their energy density, cycle performance, and safety performance. Secondary batteries contain a positive electrode and a negative electrode, and tabs are metal conductors that extend the positive and negative electrodes from the battery cell. In simple terms, they are the ears of the positive and negative electrodes of the battery and the contact points between the positive and negative electrodes during charging and discharging.

[0003] However, there is a possibility that the tab and the battery cell body may come into contact during battery charging and discharging, posing a safety risk of short-circuiting the battery cell. In conventional technologies, an insulating layer is typically coated on the tab area of ​​the electrode sheet. When the tab is bent, the insulating layer isolates the tab body from the battery cell body, preventing direct contact between the tab and the battery cell body, making it less likely that a short circuit will occur inside the battery cell. However, because the end surfaces of the tab are not protected by an insulating layer, when the tab is bent, the end surfaces of the tab may come into contact with the battery cell body, causing a short circuit in the battery cell. Therefore, there is room for improvement in the tab insulation methods used in conventional technologies. Summary of the Invention [Problem to be solved by the invention]

[0004] The present application has been made in view of the above-mentioned problems, and its purpose is to provide a tape for electrode tabs, which has a specific adhesive layer structure, and the tape wraps around the edge of the tab, thereby fundamentally preventing contact between the tab and the battery cell body, and preventing interference from the top cover when the battery cell is inserted into a case, thereby improving the safety performance of the secondary battery. [Means for solving the problem]

[0005] In order to achieve the above object, a first aspect of the present application provides a tape for electrode tabs, comprising a base layer and an adhesive layer, wherein the adhesive layer extends from one side edge of the tape in the width direction and has thick and thin regions, the thick regions are distributed along one side edge of the tape, the adhesive layer thickness of the thick regions is greater than the adhesive layer thickness of the thin regions, and the ratio of the area of ​​the thin regions to the area of ​​the thick regions is 1:0.02-0.25, preferably 1:0.025-0.18, and more preferably 1:0.0275-0.125.

[0006] Regardless of theory, the applicant has found through research that a tape having an adhesive layer with a thick region having the above area ratio has strong adhesive ability, tightly envelops the electrode tab, fundamentally preventing contact between the tab and the battery cell body, and prevents the top cover from interfering when the battery cell is inserted into the case, thereby improving the safety performance of the secondary battery.

[0007] In any embodiment, in the width direction of the adhesive layer, based on the width of the tape, the width of the thickened region is 1-20%, based on the surface area of ​​the tape, the area occupancy of the thickened region is 1-20%, preferably 2-15%, more preferably 2.5-12%, and the area occupancy of the thinned region is 80-99%, preferably 85-98%, more preferably 88-97.5%, thereby allowing the tape to be more firmly attached to the tab, thereby improving the safety performance of the secondary battery.

[0008] In an optional embodiment, the adhesive layer thickness of the thickened region is 7-15 micrometers, the adhesive layer thickness of the thinned region is 15-40% of the adhesive layer thickness of the thickened region, and the width of the tape is 2-14 mm, which allows the tape to be more firmly attached to the tab, thereby improving the safety performance of the secondary battery.

[0009] In one embodiment, the tape has through holes, which are arranged in rows along the centerline of the tape, with a row pitch of 5-15 mm and a hole diameter of 100 μm-1000 μm, so that the through holes can reduce the tensile strength of the tape and prevent the top cover from interfering with the insertion of the battery cell into the case, thereby improving the safety performance of the secondary battery.

[0010] In any embodiment, the adhesive strength of the tape is ≧2 N / m, which allows the tape to be more firmly attached to the tab, thereby improving the safety performance of the secondary battery.

[0011] In any embodiment, the average deviation of the thickness of the thickened region extending from one side edge of the tape along the width direction does not exceed 10%, preferably does not exceed 8%, and more preferably does not exceed 5%, thereby allowing the tape to be more firmly attached to the tab, thereby improving the safety performance of the secondary battery.

[0012] In an optional embodiment, the thickened region extends from one side edge of the tape in the width direction and has discrete protrusions distributed in a dotted pattern, which allows the tape to be more firmly attached to the tab, thereby improving the safety performance of the secondary battery.

[0013] In any embodiment, the color of the tape may include, but is not limited to, yellow, brown, green, blue, or white, so that the tape identifies the positive and negative tabs for subsequent manipulation.

[0014] A second aspect of the present application further provides use of a tape for attaching a tab of an electrode sheet of a secondary battery according to the first aspect of the present application, whereby the tape wraps around the edge of the tab, thereby fundamentally preventing contact between the tab and the battery cell body, and preventing interference with the top cover when the battery cell is inserted into a case, thereby improving the safety performance of the secondary battery.

[0015] A third aspect of the present application further provides a method for attaching a tab of an electrode sheet of a secondary battery using the tape according to the first aspect of the present application, the method comprising: (1) providing an electrode sheet having a tab; (2) using the tape according to the first aspect of the present application to attach both sides of the tab, thereby attaching the thick region of the tape to the electrode sheet, and at the same time, the thin region enveloping the end face of the tab and attaching the tape on both sides of the tab together.

[0016] This allows the tape and tab to be tightly bonded, preventing contact between the tab and the battery cell body, and preventing interference from the top cover when the battery cell is inserted into the case, thereby improving the safety performance of the secondary battery.

[0017] A fourth aspect of the present application further provides a secondary battery comprising a positive electrode sheet or a negative electrode sheet to which the tape of the first aspect of the present application is attached.

[0018] A third aspect of the present application provides a secondary battery comprising a positive electrode active material according to the first aspect of the present application or a positive electrode active material produced by the method according to the second aspect of the present application.

[0019] A fourth aspect of the present application provides a battery module including the secondary battery according to the third aspect of the present application.

[0020] A fifth aspect of the present application provides a battery pack including the battery module according to the fourth aspect of the present application.

[0021] A sixth aspect of the present application provides an electric device including at least one selected from the secondary battery according to the third aspect of the present application, the battery module according to the fourth aspect of the present application, or the battery pack according to the fifth aspect of the present application. [Effects of the Invention]

[0022] The tape of the present application has a specific adhesive layer structure, and the tape wraps around the edge of the tab, thereby fundamentally preventing contact between the tab and the battery cell body and preventing the top cover from interfering when the battery cell is inserted into a case, thereby improving the safety performance of the secondary battery. The tape also has specific through-holes, which can reduce the tensile strength of the tape and further prevent the top cover from interfering when the battery cell is inserted into a case. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic diagram illustrating a secondary battery according to an embodiment of the present application. [Figure 2] FIG. 2 is an exploded view showing the secondary battery according to the embodiment of the present invention shown in FIG. [Figure 3] 1 is a schematic diagram illustrating a battery module according to an embodiment of the present application. [Figure 4] 1 is a schematic diagram illustrating a battery pack according to an embodiment of the present application. [Figure 5] 5 is an exploded view showing the battery pack according to the embodiment of the present invention shown in FIG. 4. [Figure 6] 1 is a schematic diagram illustrating an electrical device that uses a secondary battery as a power source according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, with appropriate reference to the drawings, embodiments specifically disclosing the electrode tab tape, its use, application method, secondary battery, battery module, battery pack, and electrical device of the present application will be described in detail. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of the same actual structure may be omitted. This is to avoid unnecessarily lengthening the following description and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and do not limit the subject matter recited in the claims.

[0025] The "ranges" disclosed herein are defined in the form of lower and upper limits. A given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of that particular range. Such defined ranges may be inclusive or exclusive, and may be arbitrarily combined; i.e., any lower limit may be combined with any upper limit to form a single range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if minimum range values ​​1 and 2 and maximum range values ​​3, 4, and 5 are listed, the following ranges are also contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. Unless otherwise specified, the numerical range "ab" herein refers to a shorthand notation for any combination of real numbers from a to b, where both a and b are real numbers. For example, the numerical range "0-5" refers to all real numbers between "0-5" listed herein, and "0-5" is simply a shorthand notation for combinations of these numbers. Also, when a parameter refers to an integer ≧2, this is equivalent to disclosing that the parameter is an integer, e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0026] Unless otherwise specified, all embodiments and preferred embodiments in this application can be combined with each other to form new technical solutions.

[0027] Unless otherwise specified, all technical features and preferred technical features of the present application can be combined with each other to form new technical solutions.

[0028] Unless otherwise specified, all steps herein may be performed sequentially or randomly, preferably sequentially. For example, a description of a method including steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, a description of a method mentioned above that may include step (c) indicates that step (c) can be added to the method in any order, e.g., the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b).

[0029] Unless otherwise specified, the terms "comprise" and "include" used in this application may be open-ended or exclusive. For example, the terms "comprise" and "include" may further comprise or include other components not listed, or may comprise or include only the listed components.

[0030] Unless otherwise specified, in this application, the term "or" is inclusive. For example, the words "A or B" indicate "A, B, or both A and B." More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) but B is true (or exists), or both A and B are true (or exist).

[0031] A secondary battery includes a positive electrode and a negative electrode. The tabs are metal conductors that pull the positive and negative electrodes out of the battery cell. In simple terms, they are the ears of the battery's positive and negative electrodes, and the contact points between the positive and negative electrodes during charging and discharging. However, contact between the tabs and the battery cell body during charging and discharging can pose a safety risk of short-circuiting the battery cell. In conventional technologies, an insulating layer is typically coated on the tab area of ​​the electrode sheet. When the tab is bent, the insulating layer isolates the tab body from the battery cell body, preventing direct contact between the tab and the battery cell body and reducing the risk of short-circuiting within the battery cell. However, because the end surfaces of the tab are not protected by the insulating layer, when the tab is bent, the end surfaces of the tab come into contact with the battery cell body, causing a short-circuit. Therefore, there is room for improvement in the tab insulation methods used in conventional technologies. The present application has been made in view of the above-mentioned problems, and its purpose is to provide a tape for electrode tabs, which has a specific adhesive layer structure, and the tape wraps around the edge of the tab, thereby fundamentally preventing contact between the tab and the battery cell body, and preventing interference from the top cover when the battery cell is inserted into a case, thereby improving the safety performance of the secondary battery.

[0032] Battery tab tape In one embodiment of the present application, the present application provides a tape for electrode tabs, including a base layer and an adhesive layer, wherein the adhesive layer extends from one side edge of the tape in a width direction and has thick regions and thin regions, the thick regions are distributed along one side edge of the tape, the adhesive layer thickness of the thick regions is greater than the adhesive layer thickness of the thin regions, and the ratio of the area of ​​the thin regions to the area of ​​the thick regions is 1:0.02-0.25, preferably 1:0.025-0.18, and more preferably 1:0.0275-0.125.

[0033] Although the principle is not yet clear, the applicant has unexpectedly discovered that by using the tape of the present application to set an adhesive layer including a thickened area of ​​a specific proportion on the tape and using the tape to wrap around the edge of the tab, it is possible to fundamentally prevent contact between the tab and the battery cell body and to prevent the top cover from interfering when the battery cell is inserted into a case, thereby improving the safety performance of the secondary battery.

[0034] In some embodiments, in the width direction of the adhesive layer, the width of the thickened region is 1-20% based on the width of the tape, the area occupancy of the thickened region is 1-20%, preferably 2-15%, more preferably 2.5-12%, based on the surface area of ​​the tape, and the area occupancy of the thinned region is 80-99%, preferably 85-98%, more preferably 88-97.5%, thereby allowing the tape to be more firmly attached to the tab, thereby improving the safety performance of the secondary battery.

[0035] In some embodiments, the adhesive layer thickness of the thickened region is 7-15 micrometers, the adhesive layer thickness of the thinned region is 15-40% of the adhesive layer thickness of the thickened region, and the width of the tape is 2-14 mm, which allows the tape to be more firmly attached to the tab, thereby improving the safety performance of the secondary battery.

[0036] In some embodiments, the resulting tape has a width of 2-14 mm, a width of the thickened region of 1-2 mm, a thickness of 7-15 μm, an area occupancy rate of the thickened region of 1%-20% based on the surface area of ​​the tape, and a width of the thinned region of 0-13 mm, a thickness of 1-5 μm.

[0037] In some embodiments, the tape has through holes, which are distributed in rows along the centerline of the tape, with a row pitch of 5-15 mm and a hole diameter of 100 μm-1000 μm, which can reduce the tensile strength of the tape and prevent the top cover from interfering with the insertion of the battery cell into the case, thereby improving the safety performance of the secondary battery.

[0038] In some embodiments, the adhesive strength of the tape is ≧2 N / m, which allows the tape to adhere more firmly to the tab, thereby improving the safety performance of the secondary battery.

[0039] In some embodiments, the tape has an adhesive strength of 2N / m-100N / m and a tensile strength of 1Mpa-150Mpa.

[0040] In some embodiments, the average deviation of the thickness of the thickened region extending from one side edge of the tape along the width direction does not exceed 10%, preferably does not exceed 8%, and more preferably does not exceed 5%, thereby allowing the tape to be more firmly attached to the tab, thereby improving the safety performance of the secondary battery.

[0041] In some embodiments, the thickened region extends from one side edge of the tape in the width direction and has discrete protrusions distributed in a dotted pattern, which allows the tape to be more firmly attached to the tab, thereby improving the safety performance of the secondary battery.

[0042] In some embodiments, the material used as the adhesive layer of the tape is generally known to those skilled in the art. For example, the material used as the adhesive layer of the tape can be selected from one or more combinations of acrylic acid-methacrylic acid copolymer, acrylic acid-butenoic acid copolymer, acrylic acid-itaconic acid copolymer, acrylic acid-maleic acid copolymer, acrylic acid-methyl methacrylate copolymer, acrylic acid-ethyl methacrylate copolymer, acrylic acid-n-butyl methacrylate copolymer, acrylic acid-isobutyl methacrylate copolymer, polypropylene, polyethylene, polybutadiene rubber, ethylene-propylene acetate copolymer, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, maleic anhydride-modified polyolefin, poly(butadiene-acrylonitrile), styrene-maleic anhydride copolymer, etc., preferably ethylene-propylene copolymer. Typically, the adhesive is prepared by mixing the above materials with toluene.

[0043] In some embodiments, the material used for the base layer of the tape is generally known to those skilled in the art, and may be selected from the group consisting of PET (polyethylene terephthalate), PE (polyethylene), PP (polypropylene), PI (polyimide), and BOPP (biaxially oriented polypropylene film), and is preferably PET.

[0044] In some embodiments, an adhesive layer may be applied to one side of the substrate layer, followed by a release agent on the other side to prevent the tape from sticking when wound and unwound. The release agent may be selected from one or more of a silicone-based release agent, a fluorine-containing release agent, and a non-silicone-based release agent, and the tape release agent described herein is selected from a non-silicone-based release agent.

[0045] In some embodiments, a release agent is coated on the surface of the substrate layer to form a release film, and then an adhesive layer is applied to the surface of another layer of the substrate layer. The release film is typically a PET release film, a PP release film, a PE release film, etc., and preferably a PET release film.

[0046] In some embodiments, the tape colors include, but are not limited to, yellow, brown, green, blue, and white, so that the tape identifies the positive and negative tabs for subsequent manipulation.

[0047] In some embodiments, the tape is manufactured by a method known to those skilled in the art. Typically, a glue made from an adhesive layer material is applied onto a release film, dried in an oven, and then wound up together with the release film to obtain the tape. The application can be performed by any of the following methods: microgravure, comma, or slit. By controlling application parameters such as pump speed, an adhesive layer having thick and thin regions can be coated. Preferably, the adhesive layer is first coated on one side of the substrate layer, and then a release agent is applied to the other side of the substrate, dried in an oven, and then wound up. Here, the release agent is applied in the same manner as for the adhesive layer.

[0048] In some embodiments, during the winding process, the release film is simultaneously torn and finally cut into tapes of different widths, so that the release film can be recycled, saving resources and reducing costs.

[0049] A second aspect of the present application further provides a use of the tape according to the first aspect of the present application for attaching a tab of an electrode sheet of a secondary battery, whereby the tape wraps around the edge of the tab, thereby fundamentally preventing contact between the tab and the battery cell body and preventing interference with the top cover when the battery cell is inserted into a case, thereby improving the safety performance of the secondary battery.

[0050] A third aspect of the present application further provides a method for attaching a tab of an electrode sheet of a secondary battery using the tape according to the first aspect of the present application, the method comprising: (1) providing an electrode sheet having a tab; (2) using the tape according to the first aspect of the present application to attach both sides of the tab, thereby attaching the thick region of the tape to the electrode sheet, and at the same time, the thin region enveloping the end face of the tab and attaching the tape on both sides of the tab together.

[0051] This allows the tape and tab to be tightly bonded, preventing contact between the tab and the battery cell body, and preventing interference from the top cover when the battery cell is inserted into the case, thereby improving the safety performance of the secondary battery.

[0052] A fourth aspect of the present application further provides a secondary battery comprising a positive electrode sheet or a negative electrode sheet to which the tape of the first aspect of the present application is attached.

[0053] Hereinafter, the secondary battery, battery module, battery pack, and electrical device of the present application will be described with appropriate reference to the drawings.

[0054] In one embodiment of the present application, a secondary battery is provided.

[0055] A typical secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During the charge and discharge process, active ions are absorbed and released back and forth between the positive and negative electrode sheets. The electrolyte serves to conduct ions between the positive and negative electrode sheets. The separator, located between the positive and negative electrode sheets, primarily serves to prevent short circuits between the positive and negative electrodes while allowing ions to pass through.

[0056] [Positive electrode sheet] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector, the positive electrode film layer including the positive electrode active material according to the first aspect of the present application.

[0057] In some embodiments, a tape according to the first aspect of the present application is applied to the tab of the positive electrode sheet.

[0058] For example, the positive electrode current collector has two surfaces facing each other in the thickness direction thereof, and the positive electrode film layer is provided on either one or both of the two facing surfaces of the positive electrode current collector.

[0059] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, aluminum foil may be used as the metal foil sheet. The composite current collector includes a polymer substrate layer and a metal layer formed on at least one surface of the polymer substrate layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0060] In some embodiments, the positive electrode active material may be a battery positive electrode active material known in the art. For example, the positive electrode active material may include at least one of lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and modified compounds thereof. The present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials in batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include cobalt lithium oxide (e.g., LiCoO), nickel lithium oxide (e.g., LiNiO), lithium manganese oxide (e.g., LiMnO, LiMnO), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (can also be abbreviated as LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (can also be abbreviated as LiNi 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (can also be abbreviated as LiNi 0.6 Co 0.2 Mn 0.2O2(NCM 622 (can also be abbreviated as LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM 811 ), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 O2) and modified compounds thereof, etc. Examples of the lithium-containing phosphate having an olivine structure include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which can also be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0061] In some embodiments, the positive electrode membrane layer preferably further includes a binder, for example, at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0062] In some embodiments, the positive electrode film layer preferably further comprises a conductive agent, for example, superconducting carbon, acetylene black, carbon black, cochin black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0063] In some embodiments, a positive electrode sheet can be manufactured as follows: the components for manufacturing the positive electrode sheet, such as the positive electrode active material, conductive agent, binder, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, which is then coated onto a positive electrode current collector, followed by processes such as drying and cold pressing, to obtain a positive electrode sheet.

[0064] [Negative electrode sheet] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0065] In some embodiments, a tape according to the first aspect of the present application is applied to the tab of the negative electrode sheet.

[0066] For example, the negative electrode current collector has two surfaces opposing each other in the thickness direction thereof, and the negative electrode film layer is provided on either one or both of the two opposing surfaces of the negative electrode current collector.

[0067] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, copper foil may be used as the metal foil sheet. The composite current collector may include a polymer substrate layer and a metal layer formed on at least one surface of the polymer substrate layer. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0068] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of tin, stannate compounds, and tin alloys. However, the present application is not limited to these materials, and other conventional materials usable as negative electrode active materials in batteries may also be used. These negative electrode active materials may be used alone or in combination.

[0069] In some embodiments, the negative electrode membrane layer preferably further comprises a binder, which may be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0070] In some embodiments, the negative electrode film layer preferably further comprises a conductive agent, which may be selected from the group consisting of superconducting carbon, acetylene black, carbon black, cochin black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0071] In some embodiments, the negative electrode membrane layer preferably further comprises other auxiliary agents such as a thickener (eg, carboxymethylcellulose sodium (CMC-Na)).

[0072] In some embodiments, the negative electrode sheet can be manufactured as follows: The above-mentioned components for manufacturing the negative electrode sheet, such as the negative electrode active material, conductive agent, binder, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a negative electrode slurry, which is then coated onto a negative electrode current collector, and the negative electrode sheet can be obtained after processes such as drying and cold pressing.

[0073] [Electrolyte] The electrolyte serves to conduct ions between the positive electrode sheet and the negative electrode sheet. The present application is not specifically limited to the type of electrolyte, and it can be selected as needed. For example, the electrolyte can be liquid, gelled, or all solid.

[0074] In some embodiments, the electrolyte is an electrolytic solution, which includes an electrolyte salt and a solvent.

[0075] In some embodiments, the electrolyte salt can be selected from one or more of lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium bisfluorosulfonylimide (LiFSI), lithium bistrifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium bis(oxalate)borate (LiBOB), lithium difluorophosphate (LiPOF), lithium difluorooxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0076] In some embodiments, the solvent can be selected from one or more of fluoroethylene carbonate (FEC), ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethylene propyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0077] In some embodiments, the electrolyte solution preferably further contains an additive. For example, the additive may include a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive that can improve certain battery performance, such as an additive that improves the overcharge performance of the battery or an additive that improves the high-temperature or low-temperature performance of the battery.

[0078] [Separator] In some embodiments, the secondary battery further includes a separator. The present application is not particularly limited to the type of separator, and any known porous separator having good chemical and mechanical stability can be selected.

[0079] In some embodiments, the separator may be made of at least one material selected from the group consisting of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator is not particularly limited and may be a single-layer thin film or a multi-layer composite thin film. When the separator is a multi-layer composite thin film, the materials of each layer are not particularly limited and may be the same or different.

[0080] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be manufactured into an electrode assembly by a winding process or a lamination process.

[0081] In some embodiments, the secondary battery may include a housing, which can be used to seal the electrode assembly and electrolyte.

[0082] In some embodiments, the exterior of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the exterior of the secondary battery may be a soft bag, such as a pouch soft bag. The soft bag may be made of plastic, such as polypropylene, polybutylene terephthalate, or polybutylene succinate.

[0083] The present application is not particularly limited to the shape of the secondary battery, and it may be cylindrical, rectangular, or any other shape. For example, Fig. 1 shows an example of a secondary battery 5 having a rectangular structure.

[0084] In some embodiments, referring to FIG. 2 , the exterior may include a housing 51 and a cover plate 53. The housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates may surround the housing 51 to form a storage chamber. The housing 51 may have an opening communicating with the storage chamber, and the cover plate 53 may cover the opening to close the storage chamber. The positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly 52 by a winding process or a lamination process. The electrode assembly 52 is sealed in the storage chamber. An electrolyte is impregnated into the electrode assembly 52. ​​The secondary battery 5 may include one or more electrode assemblies 52, and this can be selected by those skilled in the art according to specific practical needs.

[0085] In some embodiments, the secondary batteries can be assembled into a battery module, and the number of secondary batteries included in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0086] FIG. 3 shows an example of a battery module 4. Referring to FIG. 3, in the battery module 4, a plurality of secondary batteries 5 are arranged in a sequential manner along the length of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fastened together with fasteners.

[0087] Preferably, the battery module 4 may further include an outer case having a storage space, and the plurality of secondary batteries 5 are stored in the storage space.

[0088] In some embodiments, the battery modules can be further assembled into a battery pack, and the battery pack can include one or more battery modules, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery modules.

[0089] 4 and 5 show an example of a battery pack 1. Referring to FIGS. 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 provided in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 may be covered by the lower housing 3 to form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 may be distributed in any manner within the battery box.

[0090] The present application also provides an electric device, which includes at least one of the secondary battery, battery module, or battery pack provided herein. The secondary battery, battery module, or battery pack can be used as a power source for the electric device and also as an energy storage unit for the electric device. The electric device includes, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), trains, ships, satellites, energy storage systems, etc.

[0091] The electrical device can be selected from a secondary battery, a battery module, or a battery pack depending on the usage requirements.

[0092] 6 shows an example of an electric device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density demands of the secondary battery of the electric device, a battery pack or a battery module can be used.

[0093] Other examples of the device may be a mobile phone, a tablet, a laptop, etc. Such devices are usually required to be thin and can use a secondary battery as a power source.

[0094] Example

[0095] In order to make the technical problems, technical solutions, and beneficial effects solved by the present application more clear, the present application will be described in more detail below in combination with examples and drawings. Of course, the described examples are only some of the examples of the present application, and not all of the examples. The description of at least one exemplary example below is for illustrative purposes only and does not constitute any limitation on the present application and its applications. Based on the examples of the present application, all other examples obtained by those skilled in the art without creative effort fall within the scope of the claims of the present application.

[0096] If specific techniques or conditions are not indicated in the examples, they should be carried out according to the techniques or conditions described in the literature in the field or according to the product specifications. If the manufacturer of the reagents or equipment used is not indicated, they are conventional products that can be purchased commercially.

[0097] Testing Methodology

[0098] A) Tape adhesive strength Measurements are based on the international standard GB / T 2792-2014. Specifically, aluminum foil is attached to a steel plate, and then tape is attached to the aluminum foil, and the peel strength is tested at 180°. The peel strength value can be defined as the tape adhesive strength. (Note: The aluminum foil is wider than the tape.)

[0099] B) Tape tensile strength Measurements are based on the international standard GB / T 30776-2014. Specifically, a 60 mm long tape is placed on a tensioning machine, and is clamped 10 mm from the top and bottom with a jig, leaving 40 mm in the middle, and then pulled. The obtained tensile stress is the tape tensile strength.

[0100] 1. Tape manufacturing

[0101] Example 1.7 Producing a tape with a thickened area width of 2 mm First, 10 kg of ethylene-propylene copolymer (weight average molecular weight 8W, measured in accordance with GB / T 36214.2-2018) and 10 L of toluene were mixed in a stainless steel reactor and stirred at 40°C for 3 hours to produce a paste. The resulting paste was then applied to a 14 mm wide PET release film using a slit coater. One side of the slit coater was pumped at a speed of 14 rpm to obtain a thick-walled area with a width of 2 mm and a thickness of 6 ± 1.5 μm, and the other side was pumped at a speed of 20 rpm to obtain a thin-walled area with a width of 12 mm and a thickness of 1.5 ± 1 μm. The tape was then placed in an oven to dry for 15 minutes and then wound up to produce the desired tape.

[0102] A tape with a thickened region of 2 mm wide and 6 μm thick was obtained, where the area occupancy of the thickened region was 14.2% based on the surface area of ​​the tape, and the thinned region was 12 mm wide and 1.5 μm thick. The adhesive layer had an adhesive strength of 9 N / m and a tensile strength of 10 MPa.

[0103] The tapes of Examples 1.2-14 and Comparative Example 1.1 were manufactured using the same method as that of Example 1, but with adjustments to the parameters of the thickened areas of the tape and the holes in the tape. For details of the different product parameters, see Table 1.

[0104] [Table 1]

[0105] 2. Secondary battery manufacturing

[0106] Example 1 1) Preparation of positive electrode sheet (attaching the tab with tape from Preparation Example 1.1) The positive electrode active material, lithium iron phosphate, the conductive agent, acetylene black, and the binder, polyvinylidene fluoride (PVDF), are dissolved in the solvent, N-methylpyrrolidone (NMP), in a weight ratio of 96.5:1.5:2, and the mixture is thoroughly stirred and mixed to obtain a positive electrode slurry. The positive electrode slurry is then uniformly coated onto a positive electrode current collector, which is then dried, cold pressed, and cut to obtain a positive electrode sheet.

[0107] Use a die-cutting machine to cut the electrode sheet to obtain a positive electrode tab with a height of 25 mm and a width of 45 mm. Attach the tab with the tape from Preparation Example 1.1, ensuring that the thicker area of ​​the tape is attached to the active material area of ​​the positive electrode sheet.

[0108] 2) Preparation of negative electrode sheet (attaching the tab with the tape of Preparation Example 1.1) The active material, artificial graphite, the conductive agent, acetylene black, the binder, styrene butadiene rubber (SBR), and the thickener, sodium carboxymethyl cellulose (CMC), are dissolved in deionized water as a solvent in a weight ratio of 95:2:2:1 and mixed uniformly with the deionized water to produce anode slurry. The anode slurry is then uniformly coated onto the anode current collector copper foil and dried to obtain the anode film, which is then cold pressed and cut to obtain the anode sheet.

[0109] Use a die-cutting machine to cut the electrode sheet to obtain a negative electrode tab 25 mm high and 45 mm wide. Attach the tab with the tape from Preparation Example 1.1, ensuring that the thicker area of ​​the tape is attached to the active material area of ​​the negative electrode sheet.

[0110] 3) Separator A polyethylene film is used as the separator.

[0111] 4) Electrolyte production 1M LiPF6 is dissolved in a solution consisting of EC:EMC:DMC=1:1:1.

[0112] 5) Battery manufacturing The positive electrode sheet, separator, and negative electrode sheet are stacked in order, and a separator is placed between the positive and negative electrode sheets to serve as an insulator. The electrode assembly is then wound up to obtain the electrode assembly. The electrode assembly is placed in a battery housing, dried, and then an electrolyte is injected. A lithium-ion battery is then manufactured through processes such as chemical formation and leaving.

[0113] The secondary batteries of Examples 2-14 and Comparative Examples 1.1-1.2 are manufactured using the same method as the secondary battery of Example 1, but using the tapes of Examples 1.2-14 and Comparative Examples 1.1-1.2. For details of the parameters of different products, see Table 1.

[0114] Comparative Example 2

[0115] The secondary battery was manufactured in the same manner as in Example 1, but the positive and negative electrode tabs were not attached with the tape of the present invention.

[0116] 3. Battery performance test

[0117] 1. Battery cell short circuit failure rate test: The insulation resistance value is measured using an NS200 type insulation resistance meter (purchased from Telstar). If the measured ohmic impedance value is less than 10 Ω, the battery cell is determined to be short-circuited, the number of short-circuited battery cells is counted, and the failure rate is calculated by dividing the number of short-circuited battery cells by the total number of battery cells (N=50,000).

[0118] 2. Interference ratio test: If the assembled bare battery cells are installed in a case and cannot be properly installed in the case, the top cover cannot be welded to the aluminum shell, which is determined to be interference. Interference ratio (%)n=A / B A: The number of battery cells that cannot be placed in the case B: Total number of battery cells manufactured

[0119] 3. Test results for each example and comparative example According to the above method, the batteries of each example and comparative example were manufactured, and the performance parameters of each item were measured. The results are shown in Table 2 below.

[0120] [Table 2]

[0121] Comparing Examples 1-6 and Comparative Example 1, it can be seen that when a thick adhesive layer is applied to the tape, after the tape is attached to the edge of the electrode sheet, the interference ratio of the top cover is high when the battery cell is inserted into the case, which is disadvantageous for processing and manufacturing. The thicker the adhesive layer, the greater the interference ratio.

[0122] A comparison between Examples 7-9 and Comparative Example 1 shows that when a thin adhesive layer is coated on the tape, the interference ratio of the top cover is low when the battery cell is placed in the case after the tape is attached to the edge of the electrode sheet, and the thinner the adhesive layer, the lower the interference ratio.

[0123] Comparing Examples 10-13 with Examples 7-9, it can be seen that when holes are drilled in the tape and the tape is attached to the edges of the electrode sheet, and then the battery cell is inserted into the case, the interference ratio of the top cover is low, and when the hole diameter is 800 μm and the row pitch is 5 mm, the ratio is 0, and the effect is best.

[0124] From the comparative example and the example, after attaching tape to the electrode sheet, the failure rate of the battery cell is reduced to 0. It can be seen that attaching tape has a good protective effect on improving the safety performance of the battery cell.

[0125] Furthermore, from the data in Table 1, if the adhesive layer is thick, the wider it is, the greater the adhesive strength and the greater the tensile strength. If the adhesive layer is thin, the tensile strength will be lower. After punching the tape, both the adhesive strength and tensile strength will be lower, but it can still meet the processing and usage requirements.

[0126] The present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea within the scope of the technical solution of the present application and that achieves similar effects is included within the technical scope of the present application. Furthermore, various modifications of the embodiments that a person skilled in the art can conceive of, and other forms constructed by combining some of the components of the embodiments, are also included within the scope of the present application, as long as they do not deviate from the gist of the present application. [Explanation of symbols]

[0127] 1 battery pack 2 Upper box 3 Lower box 4 Battery Module 5 Secondary battery 51 Housing 52 Electrode Assembly 53 Top cover assembly

Claims

1. 1. A tape for electrode tabs, which is attached to a tab of an electrode sheet of a secondary battery, comprising a base material layer and an adhesive layer, wherein the electrode sheet includes a current collector and a tab connected to at least one end of the current collector, the adhesive layer extending in the width direction from one side edge of the tape has thick regions and thin regions, the thick regions are distributed along the one side edge of the tape, the adhesive layer thickness in the thick regions is greater than the adhesive layer thickness in the thin regions, and the ratio of the area of ​​the thin regions to the area of ​​the thick regions is 1:0.02-0.

25.

2. 2. The tape of claim 1, wherein, in the width direction of the adhesive layer, the width of the thickened region is 1-20% based on the width of the tape, the area occupancy rate of the thickened region is 1-20% based on the surface area of ​​the tape, and the area occupancy rate of the thinned region is 80-99% based on the surface area of ​​the tape.

3. 3. The tape of claim 1, wherein the adhesive layer thickness in the thickened regions is 7-15 microns, the adhesive layer thickness in the thinned regions is 15-40% of the adhesive layer thickness in the thickened regions, and the tape width is 2-14 mm.

4. The tape according to claim 1 or 2, characterized in that the tape has through holes, the through holes being distributed in rows along the center line of the tape, the row pitch being 5-15 mm, and the hole diameter being 100 μm-1000 μm.

5. 3. Tape according to claim 1 or 2, characterized in that the adhesive strength of the tape, measured according to standard GB / T 2792-2014, is ≧2 N / m.

6. 3. The tape of claim 1, wherein the average deviation in thickness of the thickened region extending from one side edge of the tape along the width direction does not exceed 10%.

7. 3. The tape according to claim 1, wherein the thickened region has discontinuous protrusions distributed in a dot pattern, the protrusions extending from one side edge of the tape in the width direction.

8. 3. The tape according to claim 1, wherein the color of the tape includes yellow, brown, green, blue, and white.

9. Use of the tape according to claim 1 or 2 for adhering to the tabs of electrode sheets of secondary batteries.

10. A method for attaching the tape according to claim 1 or 2 to a tab of an electrode sheet of a secondary battery, comprising the steps of: (1) providing an electrode sheet having a tab; (2) A method for using tape to attach a tab of an electrode sheet of a secondary battery using tape, the method comprising the steps of: using the tape according to claim 1 or 2 to attach the tape to the front and back surfaces of the tab that face each other in the thickness direction, thereby attaching the thick region of the tape to the electrode sheet, and at the same time, having the thin region wrap around the end face of the tab, thereby attaching the tape attached to the front surface of the tab and the tape attached to the back surface of the tab together, wherein the end face of the tab is the end face in the direction in which the tab is pulled out from the electrode sheet.

11. A secondary battery comprising a positive electrode sheet or a negative electrode sheet to which the tape according to claim 1 is attached.

12. A battery module comprising the secondary battery according to claim 11.

13. A battery pack comprising the battery module according to claim 12.

14. An electric device comprising at least one selected from the group consisting of the secondary battery according to claim 11, the battery module according to claim 12, and the battery pack according to claim 13.

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