Electrode and secondary battery

Abstract

The present disclosure relates to an electrode. The technical problem to be solved is to provide an electrode with a reinforced substrate. To this end, the present disclosure provides an electrode comprising: a substrate; a coating layer provided on a first region which is a part of the substrate; a reinforcing layer provided on a second region which is another part of the substrate; and a tab provided on the second region and electrically connected to the substrate.

Description

Electrodes and secondary batteries

[0001] The present disclosure relates to an electrode having enhanced reliability and stability and a secondary battery including such an electrode.

[0002]

[0003] Secondary batteries, unlike non-rechargeable primary batteries, are rechargeable and dischargeable. Low-capacity secondary batteries are used in small, portable electronic devices such as smartphones, feature phones, laptop computers, digital cameras, and camcorders, while large-capacity secondary batteries are widely used as power sources for motor drives and power storage in hybrid and electric vehicles. These secondary batteries include electrodes including a positive electrode and / or a negative electrode, an electrode assembly including the electrode, a case housing the electrode assembly, and electrode terminals connected to the electrode assembly.

[0004] As technology advances, high-capacity and / or high-power secondary batteries are in demand. Accordingly, multiple secondary batteries can be electrically connected and used. For example, secondary batteries can be applied to electronic devices in the form of secondary battery modules comprising multiple secondary batteries and / or secondary battery packs comprising multiple secondary battery modules. In this case, the electronic devices are electronic devices requiring high power and / or high capacity, such as electric vehicles.

[0005] As described above, a secondary battery includes electrodes, each comprising a positive electrode and / or a negative electrode. Furthermore, the secondary battery further includes a tab for electrically connecting the electrode to the outside world. The tab is attached to a portion of the electrode and electrically connects the electrode to the outside world. When attached to the electrode, the tab presses against the electrode due to a difference in elongation between the electrode and the outside world and / or when subjected to an external force. In this case, cracks may occur on the inside and outside of the electrode due to the tab.

[0006] Cracks in the electrodes can reduce the capacity and lifespan of the secondary battery, lowering its reliability. Furthermore, cracks can cause short-circuits and fires, lowering the battery's safety. Therefore, measures are needed to prevent cracks in the electrodes.

[0007] The above-described information disclosed in the background technology of this invention is only intended to improve understanding of the background of the present invention, and therefore may include information that does not constitute prior art.

[0008]

[0009] The present invention provides an electrode that prevents cracks from occurring in the electrode through a reinforcing layer and / or a secondary battery including such an electrode.

[0010] The present invention provides an electrode that protects the electrode through an insulating layer and / or a secondary battery including such an electrode.

[0011] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0012]

[0013] 1. An electrode according to one embodiment of the present invention for solving the above technical problem is characterized by including: a substrate; a coating layer provided on a first region that is a part of the substrate; a reinforcing layer provided on a second region that is another part of the substrate; and a tab provided on the second region and electrically connected to the substrate.

[0014] 2. In the above 1 specific example, the reinforcing layer can be formed with the same thickness as the coating layer.

[0015] 3. In the above 1 or 2 specific examples, the reinforcing layer may be formed with a thickness thinner than the thickness of the coating layer.

[0016] 4. In any one of the above embodiments 1 to 3, the reinforcing layer may include a conductive material.

[0017] 5. In any one of the specific examples 1 to 4 above, the reinforcing layer may include the same material as the material included in the substrate.

[0018] 6. In any one of the above embodiments 1 to 5, the reinforcing layer may be formed to have a larger area than the tab in the direction toward the second region.

[0019] 7. In any one of the above embodiments 1 to 6, the reinforcing layer may be positioned between the substrate and the tab.

[0020] 8. In any one of the specific examples 1 to 7 above, the substrate may have the reinforcing layer provided on one side of the second region, and the tab provided on the other side of the second region.

[0021] 9. In any one of the specific examples 1 to 8 above, the substrate can be formed with a tensile strength of 285 N / mm2 or more.

[0022] 10. In any one of the embodiments 1 to 9 above, the electrode may further include an insulating layer provided on the second region while covering the tab and including an insulating material.

[0023] 11. According to one embodiment of the present invention for solving the above technical problem, a secondary battery comprises: an electrode assembly including a negative electrode, a positive electrode, and a separator positioned between the negative electrode and the positive electrode; and a case for accommodating the electrode assembly; wherein at least one of the negative electrode and the positive electrode comprises: a substrate; a coating layer provided on a first region that is a part of the substrate; a reinforcing layer provided on a second region that is another part of the substrate; and a tab provided on the second region and electrically connected to the substrate.

[0024] 12. In the above 11 specific examples, the reinforcing layer may be formed with a thickness less than or equal to the thickness of the coating layer.

[0025] 13. In the above 11 or 12 specific examples, the reinforcing layer may include the same material as the material included in the substrate.

[0026] 14. In any one of the specific examples 11 to 13, the reinforcing layer may be formed to have a larger area than the tab in the direction toward the second region.

[0027] 15. In any one of the specific examples 11 to 14, the reinforcing layer may include a first reinforcing layer provided between one side of the substrate and the tab; and a second reinforcing layer provided on the other side of the substrate.

[0028]

[0029] According to the present invention, an electrode having an effect of increasing the thickness of a substrate and / or a secondary battery including such an electrode can be provided.

[0030] According to the present invention, an electrode having increased properties and / or a secondary battery including such an electrode can be provided.

[0031] According to the present invention, it is possible to provide an electrode that is prevented from cracking inside and outside and / or a secondary battery including such an electrode.

[0032] According to the present invention, it is possible to provide an electrode capable of more efficiently preventing cracks from occurring and / or a secondary battery including such an electrode.

[0033] However, the effects that can be obtained through the present invention are not limited to the effects described above, and other technical effects that are not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0034]

[0035] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0036] Figures 1 to 4 are cross-sectional views schematically showing a lithium secondary battery according to one embodiment.

[0037] Figure 5 shows a cross-sectional view of an electrode according to one embodiment.

[0038] Figure 6 shows a cross-sectional view of an electrode according to one embodiment.

[0039] Figure 7 shows a top view of an electrode according to one embodiment.

[0040] Figure 8 shows a cross-sectional view of an electrode according to one embodiment.

[0041] Figure 9 shows a cross-sectional view of an electrode according to one embodiment.

[0042] Figure 10 shows a cross-sectional view of an electrode according to one embodiment.

[0043]

[0044] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention. The present invention is defined solely by the scope of the claims set forth below.

[0045] Unless otherwise specified herein, when a part such as a layer, film, region, or plate is said to be “on top of” another part, this includes not only cases where it is “directly on top of” the other part, but also cases where there are other parts in between.

[0046] Unless otherwise specified herein, the singular may also include the plural. Furthermore, unless otherwise specified, "A or B" may mean "including A, including B, or including A and B."

[0047] As used herein, “combination thereof” may mean mixtures, laminates, composites, copolymers, alloys, blends, and reaction products of the components.

[0048] Unless otherwise defined herein, the particle size may be the average particle size. In addition, the particle size refers to the average particle size (D50), which means the diameter of particles with a cumulative volume of 50% by volume in a particle size distribution. The average particle size (D50) can be measured by a method well known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope (TEM) photograph or a scanning electron microscope (SEM) photograph. Alternatively, the average particle size (D50) value can be obtained by measuring with a measuring device that utilizes dynamic light-scattering, performing data analysis to count the number of particles for each particle size range, and calculating from the counted number. Alternatively, the average particle size (D50) value can be obtained by measuring with a laser diffraction method. When measuring by laser diffraction, more specifically, after the particles to be measured are dispersed in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasonic waves of approximately 28 kHz at an output of 60 W, and the average particle size (D50) based on 50% of the particle size distribution in the measuring device can be calculated.

[0049]

[0050] Figures 1 to 4 are cross-sectional views schematically showing a lithium secondary battery according to one embodiment.

[0051] Lithium secondary battery (100)

[0052] The lithium secondary battery (100) can be classified into a cylindrical shape, a square shape, a pouch shape, a coin shape, etc. according to its shape. FIGS. 1 to 4 are schematic diagrams illustrating a lithium secondary battery according to an embodiment, in which FIG. 1 can be said to be a cylindrical shape, FIG. 2 a square shape, and FIGS. 3 and 4 a pouch shape. Referring to FIGS. 1 to 4, the lithium secondary battery (100) may include an electrode assembly (40) having a separator (30) interposed between a positive electrode (10) and a negative electrode (20), and a case (50) in which the electrode assembly (40) is built. The positive electrode (10), the negative electrode (20), and the separator (30) may be impregnated with an electrolyte (not shown). The lithium secondary battery (100) may include a sealing member (60) that seals the case (50) as shown in FIG. 1. In addition, in FIG. 2, the lithium secondary battery (100) may include a positive lead tab (11), a positive terminal (12), a negative lead tab (21), and a negative terminal (22). As in FIGS. 3 and 4, the lithium secondary battery (100) may include electrode tabs (70), i.e., a positive tab (71) and a negative tab (72), which serve as electrical paths for inducing current formed in the electrode assembly (40) to the outside.

[0053]

[0054] positive electrode active material

[0055] A compound capable of reversible intercalation and deintercalation of lithium (a lithiated intercalation compound) can be used as a cathode active material. Specifically, one or more of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof can be used.

[0056] The above composite oxide may be a lithium transition metal composite oxide, and specific examples thereof include lithium nickel-based oxide, lithium cobalt-based oxide, lithium manganese-based oxide, lithium iron phosphate-based compound, cobalt-free nickel-manganese-based oxide, or a combination thereof.

[0057] As an example, a compound represented by any one of the following chemical formulas may be used: Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Lia Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3(0≤f≤2); Li a FePO4(0.90≤a≤1.8).

[0058] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; L 1 is Mn, Al or a combination thereof.

[0059] For example, the cathode active material may be a high-nickel cathode active material in which the nickel content is 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more and 99 mol% or less, based on 100 mol% of metals excluding lithium in a lithium transition metal composite oxide. The high-nickel cathode active material can realize high capacity and thus can be applied to high-capacity, high-density lithium secondary batteries.

[0060]

[0061] Bipolar (10)

[0062] A positive electrode (10) for a lithium secondary battery (100) may include a current collector and a positive electrode active material layer formed on the current collector. The positive electrode active material layer includes a positive electrode active material and may further include a binder and / or a conductive material.

[0063] For example, the anode may further include an additive that can act as a sacrificial anode.

[0064] The content of the positive electrode active material may be 90 wt% to 99.5 wt% with respect to 100 wt% of the positive electrode active material layer, and the contents of the binder and conductive material may be 0.5 wt% to 5 wt%, respectively, with respect to 100 wt% of the positive electrode active material layer.

[0065] The above binder serves to adhere the positive electrode active material particles well to each other and also to adhere the positive electrode active material well to the current collector. Representative examples of the binder include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, etc.

[0066] The conductive material is used to provide conductivity to the electrode, and any material that does not cause chemical changes and is electronically conductive can be used in the battery. Examples of the conductive material include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube; metal-based materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0067] Al may be used as the above current collector, but is not limited thereto.

[0068]

[0069] Negative active material

[0070] The negative electrode active material includes a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0071] The material capable of reversibly intercalating / deintercalating the lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite in an amorphous, plate-like, flake-like, spherical, or fibrous form, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0072] As the above lithium metal alloy, an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn can be used.

[0073] As the material capable of doping and dedoping the lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material may be used. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiOx (0 < x < 2), a Si-Q alloy (wherein Q is selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements (excluding Si), Group 15 elements, Group 16 elements, transition metals, rare earth elements, and combinations thereof), or a combination thereof. The Sn-based negative electrode active material may be Sn, SnO2, a Sn-based alloy, or a combination thereof.

[0074] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, the composite may include secondary particles (cores) in which silicon primary particles are assembled and an amorphous carbon coating layer (shell) positioned on the surface of the secondary particles. The amorphous carbon may also be positioned between the silicon primary particles, such that, for example, the silicon primary particles may be coated with amorphous carbon. The secondary particles may be dispersed and present in an amorphous carbon matrix.

[0075] The silicon-carbon composite may further comprise crystalline carbon. For example, the silicon-carbon composite may comprise a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer positioned on the surface of the core.

[0076] The above Si-based negative electrode active material or Sn-based negative electrode active material can be used in a mixture with a carbon-based negative electrode active material.

[0077]

[0078] Cathode (20)

[0079] A negative electrode (20) for a lithium secondary battery (100) includes a current collector and a negative electrode active material layer positioned on the current collector. The negative electrode active material layer includes a negative electrode active material and may further include a binder and / or a conductive material.

[0080] For example, the negative electrode active material layer may include 90 to 99 wt% of the negative electrode active material, 0.5 to 5 wt% of the binder, and 0 to 5 wt% of the conductive material.

[0081] The above binder serves to adhere the negative electrode active material particles well to each other and also to adhere the negative electrode active material well to the current collector. The binder may be a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof.

[0082] Examples of the non-aqueous binder include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or combinations thereof.

[0083] The above-mentioned aqueous binder may be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluoroelastomer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0084] When using an aqueous binder as the above-mentioned negative electrode binder, a cellulose-based compound capable of imparting viscosity may be further included. The cellulose-based compound may be a mixture of one or more of carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or an alkali metal salt thereof. The alkali metal may be Na, K, or Li.

[0085] The above dry binder is a polymeric material capable of being fiberized, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a combination thereof.

[0086] The above conductive material is used to provide conductivity to the electrode, and any material that does not cause chemical changes and is electronically conductive can be used in the battery to be constructed. Specific examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metal-based materials in the form of metal powder or metal fibers, including copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0087] The negative electrode current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and a combination thereof.

[0088]

[0089] Electrolyte (not shown)

[0090] An electrolyte for a lithium secondary battery (100) includes a non-aqueous organic solvent and a lithium salt.

[0091] The above non-aqueous organic solvent acts as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0092] The above non-aqueous organic solvent may be a carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvent, an aprotic solvent, or a combination thereof.

[0093] Examples of the above carbonate solvents that can be used include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC).

[0094] Ester solvents that can be used include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanolide, mevalonolactone, valerolactone, and caprolactone.

[0095] Examples of ether solvents that can be used include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and tetrahydrofuran. In addition, examples of ketone solvents that can be used include cyclohexanone. Examples of alcohol solvents that can be used include ethyl alcohol and isopropyl alcohol, and examples of aprotic solvents that can be used include nitriles such as R-CN (where R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond, an aromatic ring, or an ether group); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane and 1,4-dioxolane; and sulfolanes.

[0096] The above non-aqueous organic solvents can be used alone or in combination of two or more.

[0097] In addition, when using a carbonate solvent, a cyclic carbonate and a chain carbonate can be mixed and used, and the cyclic carbonate and the chain carbonate can be mixed in a volume ratio of 1:1 to 1:9.

[0098] The above lithium salt is a substance that dissolves in an organic solvent and acts as a source of lithium ions in the battery, enabling the basic operation of a lithium secondary battery and promoting the movement of lithium ions between the positive and negative electrodes. Representative examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide (LiFSI), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2) (x and y are integers from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalato)phosphate (LiDFOB), lithium bis(oxalato)borate (LiBOB).

[0099]

[0100] Separator (30)

[0101] Depending on the type of lithium secondary battery (100), a separator (30) may be present between the positive electrode (10) and the negative electrode (20). As the separator (30), a multilayer film of two or more layers of polyethylene, polypropylene, polyvinylidene fluoride, or these may be used, and of course, a mixed multilayer film such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, or a polypropylene / polyethylene / polypropylene three-layer separator may be used.

[0102] The above separator (30) may include a porous substrate and a coating layer including an organic material, an inorganic material, or a combination thereof located on one or both sides of the porous substrate.

[0103] The above porous substrate may be a polymer film formed of any one polymer selected from polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyacetal, polyamide, polyimide, polycarbonate, polyether ketone, polyarylether ketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene oxide, cyclic olefin copolymer, polyphenylene sulfide, polyethylene naphthalate, glass fiber, Teflon, and polytetrafluoroethylene, or a copolymer or mixture of two or more thereof.

[0104] The organic material may include a polyvinylidene fluoride polymer or a (meth)acrylic polymer.

[0105] The above inorganic materials are Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, It may include inorganic particles selected from, but not limited to, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0106] The organic and inorganic substances may be mixed and present in one coating layer, or a coating layer including an organic substance and a coating layer including an inorganic substance may be present in a laminated form.

[0107]

[0108] As described in FIGS. 1 to 4, a secondary battery (100) according to one embodiment includes an electrode assembly (40) and a case (50) housing the electrode assembly (40). The electrode assembly (40) includes a positive electrode (10), a negative electrode (20), and / or a separator (30) positioned between the positive electrode (10) and the negative electrode (20). In addition, the secondary battery (100) further includes an electrolyte that is housed in the case (50) together with the electrode assembly (40) and impregnated into the electrode assembly (40).

[0109] Specifically, the electrode included in the electrode assembly (40) includes a current collector and an active material layer provided on the current collector. At this time, in the current collector, the region where the active material layer is provided is referred to as a holding region, and the region where the current collector is exposed because the active material layer is not provided is referred to as a non-conductive region. The electrode further includes a tab provided on at least a portion of the non-conductive region. The electrode charges or discharges electric energy from the outside through the tab.

[0110] At this time, when the tab is attached to the substrate, a step is generated between the retaining portion, the unattached portion, and the unattached portion. This step causes the substrate to be subjected to pressure from the tab, and if the pressure becomes severe, cracks may occur. Alternatively, the substrate and the tab attached to the substrate have different elongations. Accordingly, when the electrode assembly is subjected to force, the substrate and the tab may bend or elongate to different degrees. In this case, cracks may occur in the region of the substrate where the tab is attached or in the surrounding region due to the difference in elongation between the substrate and the tab.

[0111] These cracks degrade the reliability and / or stability of secondary batteries containing electrodes. Therefore, a method to prevent the occurrence of cracks is required.

[0112] Meanwhile, the substrate thickness can be increased to prevent cracks in the electrode. However, this can lead to the electrode becoming excessively thick in the maintenance region, which can result in a decrease in the capacity of the secondary battery.

[0113] Meanwhile, to prevent cracks in the electrodes, a substrate with improved physical properties can be used. However, this may result in excessively high manufacturing costs for secondary batteries and / or problems with the process and design.

[0114] Therefore, a method is needed to strengthen the electrodes while ensuring the reliability and / or safety of the substrate, while avoiding problems with the process, design, or capacity. This method is described below.

[0115]

[0116] Figure 5 shows a cross-sectional view of an electrode according to one embodiment.

[0117] In Fig. 5, 200 represents an electrode according to an embodiment. The electrode (200) according to an embodiment includes a substrate (210), a coating layer (220), a reinforcing layer (240), and a tab (230).

[0118] The substrate (210) includes, for example, the current collector described in FIGS. 1 to 4. For example, if the electrode (200) is an anode, the substrate (210) may include aluminum (Al). For example, if the electrode (200) is an anode, the substrate (210) may include copper (Cu).

[0119] The substrate (210) includes a first region (A, C) and a second region (B). The first region (A, C) is a region where an active material layer is coated. The first region (A, C) may be referred to as a "maintenance region" because the active material layer is coated thereon. The second region (B) is a region where the active material layer is not coated. The second region (B) may be referred to as a "non-maintenance region."

[0120] The coating layer (220) includes, for example, an active material layer. The coating layer (220) includes an active material, a conductive material, and / or a binder.

[0121] The coating layer (220) is provided on the first region (A, C), which is a part of the substrate (210). At this time, the first region (A, C) includes a part of the region on one or both sides of the substrate (210). That is, the coating layer (220) may be formed on only one side of the substrate (210). Alternatively, the coating layer (220) may be formed on both sides of the substrate (210), as illustrated in FIG. 5. Hereinafter, an example in which the coating layer (220) is formed on both sides of the substrate (210) will be described. At this time, since the coating layer (220) is provided only on the first region (A, C), the first region (A, C) and the second region (B) may have a step difference from each other when viewed in cross section.

[0122] The tab (230) is provided on the second region (B). At this time, the second region (B) includes another part of the region on the other side or both sides of the substrate (210). That is, the second region (B) is all regions other than the first regions (A, C) on the surface of the substrate (210).

[0123] The tab (230) is electrically connected to the substrate (210). For example, the tab (230) is a structure formed to be longer in the length direction than in the width direction. At this time, one side of the tab (230) in the length direction is connected to the current collector (210). In addition, the other side of the tab (230) in the length direction extends from the current collector (210) and is positioned outside the current collector (210). That is, the tab (230) may be formed in a form in which the other side protrudes from the current collector (210). The other side of the tab (230) is electrically connected to the outside.

[0124] The reinforcing layer (240) is provided on the second region (B), which is another part of the substrate (210). For example, the reinforcing layer (240) is located between the substrate (210) and the tab (230). In this case, the reinforcing layer (240) may be provided on at least a portion of the second region (B). In addition, the tab (230) may be provided on at least a portion of the reinforcing layer (240). That is, the reinforcing layer (240) may have one side in contact with the substrate (210) and the other side in contact with the tab (230). Through this, the reinforcing layer (240) may reinforce the physical properties of the substrate (210). In addition, since the reinforcing layer (240) is located only on the second region (B), the thickness of the entire electrode (200) may be prevented from increasing and / or the capacity of the secondary battery (100) may be prevented from decreasing.

[0125] The reinforcing layer (240) includes a conductive material. Through this, the reinforcing layer (240) can reinforce the physical properties of the substrate (210) without interfering with the electrical connection between the tab (230) and the substrate (210).

[0126] At this time, the conductive material is at least one selected from the group consisting of, for example, metal, stainless steel surface-treated with metal, conductive polymer, carbon black, polymer surface-treated with metal, carbon nanotube, graphite, and conductive paste.

[0127] At this time, the metal is at least one selected from the group consisting of, for example, stainless steel, aluminum, nickel, nickel, titanium, sintered carbon, and copper.

[0128] At this time, the stainless steel surface-treated with metal is stainless steel surface-treated with at least one selected from the group consisting of carbon, nickel, titanium, and silver.

[0129] At this time, the conductive polymer is at least one selected from the group consisting of, for example, polyacetylene, polyaniline, polypyrrole, polythiophene, polysulfide, poly(3,4-ethylene dioxythio-phene) (PEDOT), and polythiophene.

[0130] At this time, the polymer surface-treated with a metal is a polymer surface-treated with one selected from the group consisting of, for example, ITO (Indium Thin Oxide), silver, palladium, and nickel.

[0131] Alternatively, the conductive material may include a combination of at least two of the conductive materials described above. In this case, the combination includes both cases where two materials are combined to form two or more layers and / or cases where two materials are mixed to form one or more layers.

[0132] For example, the reinforcing layer (240) includes the same material as the material included in the substrate (210). For example, the electrode (200) may be an anode and the substrate (210) may include aluminum (Al). In this case, the reinforcing layer (240) may include aluminum (Al). Alternatively, for example, the electrode (200) may be an anode and the substrate (210) may include copper (Cu). In this case, the reinforcing layer (240) may include copper (Cu). Through this, the reinforcing layer (240) may improve adhesion to the electrode (200). For example, when the reinforcing layer (240) is bonded to the electrode (200) through welding, the reinforcing layer (240) may improve the welding strength to the electrode (200).

[0133] Meanwhile, for example, the reinforcing layer (240) may be formed to have a tensile strength of 285 N / mm2 or more. Or, for example, the reinforcing layer (240) may be formed to have a tensile strength of 286 N / mm2 or more. Or, for example, the reinforcing layer (240) may be formed to have a tensile strength of 290 N / mm2 or more. Or, for example, the reinforcing layer (240) may be formed to have a tensile strength of 295 N / mm2 or more. Or, for example, the reinforcing layer (240) may be formed to have a tensile strength of 300 N / mm2 or more. Or, for example, the reinforcing layer (240) may be formed to have a tensile strength of 305 N / mm2 or more. Or, for example, the reinforcing layer (240) may be formed to have a tensile strength of 310 N / mm2 or more. Alternatively, for example, the reinforcing layer (240) may be formed to have a tensile strength of 315 N / mm2 or more. Alternatively, for example, the reinforcing layer (240) may be set to have a tensile strength of 300 N / mm2 or more, and the tensile strength error range may be within ±15 N / mm2. Alternatively, for example, the reinforcing layer (240) may be set to have a tensile strength of 306 N / mm2 or more, and the tensile strength error range may be within ±15 N / mm2. This is because, even if the reinforcing layer (240) is provided on the substrate (210) when the minimum tensile strength is less than 285 N / mm2, cracks may occur in the substrate (210).

[0134] Through this configuration, the electrode (200) according to one embodiment can prevent cracks from occurring. Hereinafter, various embodiments of the electrode (200) according to one embodiment will be described.

[0135]

[0136] Figure 6 shows a cross-sectional view of an electrode according to one embodiment.

[0137] In Fig. 6, 200 represents an electrode according to an embodiment. The electrode (200) according to an embodiment includes a substrate (210), a coating layer (220), a reinforcing layer (240), and a tab (230). The description of the electrode (200) and / or components included in the electrode (200) is the same as or similar to that described in Fig. 5. Therefore, in Fig. 6, any content overlapping with that described in Fig. 5 may be omitted.

[0138] A reinforcing layer (240) is provided on the substrate (210) to eliminate the step difference between the first region (A, C) and the second region (B). In this way, the reinforcing layer (240) prevents cracks from occurring in the substrate (210).

[0139] For example, the thickness (h1) of the reinforcing layer (240) can be formed to be the same as the thickness (h2) of the coating layer (220). In this case, the reinforcing layer (240) can completely eliminate the step between the first region (A, C) and the second region (B).

[0140] Alternatively, for example, the thickness (h1) of the reinforcing layer (240) may be formed thinner than the thickness (h2) of the coating layer (220). In this case, the reinforcing layer (240) may partially eliminate the step difference between the first region (A, C) and the second region (B) while reducing the cost and process difficulty required for the reinforcing layer (240).

[0141] Through this configuration, the reinforcing layer (240) can not only improve the strength and / or physical properties of the substrate (210), but also eliminate the step formed in the electrode (200) to further reduce the probability of cracks occurring in the substrate (210).

[0142]

[0143] Figure 7 shows a top view of an electrode according to one embodiment.

[0144] In Fig. 7, 200 represents an electrode according to an embodiment. The electrode (200) according to an embodiment includes a substrate (210), a coating layer (220), a reinforcing layer (240), and a tab (230). The description of the electrode (200) and / or components included in the electrode (200) is the same as or similar to that described in Figs. 5 and 6. Therefore, in Fig. 7, any content overlapping with that described in Figs. 5 and 6 may be omitted.

[0145] In Fig. 7, the width represents the length in the long side direction of the electrode (200). In Fig. 7, the length (t1) represents the length in the short side direction of the electrode (200). In Fig. 7, the upper surface is the direction facing the second region (B). The direction facing the second region (B) is the direction when the wide surface of the substrate (210) is viewed in a vertical direction. That is, it is the direction in which the reinforcing layer (240) and / or the tab (230) is provided toward the second region (B). That is, the direction facing the second region (B) is the direction when viewed toward the second region (B) in a direction perpendicular to the long side direction and the short side direction of the electrode (200).

[0146] The area of ​​the reinforcing layer (240) can be represented by a first width (w1) and a first length (t1) in the direction toward the second region (B). In addition, the area of ​​the tab (230) can be represented by a second width (w2) and a second length (t2) in the direction toward the second region (B). In this case, the area of ​​the tab (230) represents an area located on the second region (B) among the total area of ​​the tab (230), not the entire area of ​​the tab (230).

[0147] In the direction toward the second region, the area of ​​the reinforcing layer (240) is larger than the area of ​​the tab (230). For example, the first width (w1) is larger than the second width (w2). Or, for example, the first length (t1) is longer than the second length (t2).

[0148] The tab (230) may be provided on the second region (B) but may not be in direct contact with the substrate (210). For example, the first width (w1) may be greater than the second width (w2), and the first length (t1) may be longer than the second length (t2). In this case, for example, the tab (230) may be provided on the reinforcing layer (240) and thus positioned on the substrate (210). Through such a configuration, the reinforcing layer (240) may prevent the substrate (210) from being damaged by the tab (230).

[0149] Meanwhile, the contents described in FIG. 7 are merely examples. For example, the first width (w1) may be greater than the second width (w2), or the first length (t1) may be longer than the second length (t2). In this case, for example, the tabs (230) may be partially provided on the reinforcing layer (240) and partially provided on the substrate (210). Through such a configuration, the reinforcing layer (240) may reduce the material cost required for the reinforcing layer (240) while partially preventing damage to the substrate (210).

[0150]

[0151] Figure 8 shows a cross-sectional view of an electrode according to one embodiment.

[0152] In Fig. 8, 200 represents an electrode according to an embodiment. The electrode (200) according to an embodiment includes a substrate (210), a coating layer (220), a reinforcing layer (240), and a tab (230). The description of the electrode (200) and / or components included in the electrode (200) is the same as or similar to that described in Figs. 5 to 7. Therefore, in Fig. 8, any content overlapping with that described in Figs. 5 to 7 may be omitted.

[0153] For example, the reinforcing layer (240) is provided on one side of the substrate (210). In addition, for example, the tab (230) is provided on the other side of the substrate (210). That is, the reinforcing layer (240) can face the tab (230) with the substrate (210) interposed therebetween.

[0154] Through this configuration, the reinforcing layer (240) can reinforce the substrate (210) while reducing the step difference between the first region (A, C) and the second region (B). Furthermore, the reinforcing layer (240) can reinforce the substrate (210) without increasing the overall thickness of the electrode (200). Accordingly, the electrode (200) according to one embodiment can provide a high-capacity secondary battery (100) while simultaneously reinforcing the physical properties of the substrate (210).

[0155]

[0156] Figure 9 shows a cross-sectional view of an electrode according to one embodiment.

[0157] In Fig. 9, 200 represents an electrode according to an embodiment. The electrode (200) according to an embodiment includes a substrate (210), a coating layer (220), a reinforcing layer (240), and a tab (230). The description of the electrode (200) and / or components included in the electrode (200) is the same as or similar to that described in Figs. 5 to 8. Therefore, in Fig. 9, any content overlapping with that described in Figs. 5 to 8 may be omitted.

[0158] For example, the reinforcing layer (240) includes a first reinforcing layer (241) and a second reinforcing layer (242). The first reinforcing layer (241) is provided between one side of the substrate (210) and the tab (230). The first reinforcing layer (241) includes, for example, the reinforcing layer (240) described in FIGS. 5 to 7. The second reinforcing layer (242) is provided on the other side of the substrate (210). The second reinforcing layer (242) includes, for example, the reinforcing layer (240) described in FIG. 8.

[0159] Through this configuration, the electrode (200) according to one embodiment can further prevent cracks from occurring in the substrate (210).

[0160]

[0161] Figure 10 shows a cross-sectional view of an electrode according to one embodiment.

[0162] In Fig. 10, 200 represents an electrode according to an embodiment. The electrode (200) according to an embodiment includes a substrate (210), a coating layer (220), a reinforcing layer (240), and a tab (230). The description of the electrode (200) and / or components included in the electrode (200) is the same as or similar to that described in Figs. 5 to 9. Therefore, in Fig. 10, any content overlapping with that described in Figs. 5 to 9 may be omitted.

[0163] An electrode (200) according to one embodiment may further include an insulating layer (250). This insulating layer (250) is described in detail in FIG. 10.

[0164] An insulating layer (250) is provided on at least a portion of the substrate (210). The insulating layer (250) is also formed on the substrate (210) while covering at least a portion of the tab (230). Alternatively, the insulating layer (250) is formed on the substrate (210) while covering at least a portion of the tab (230) and / or the reinforcing layer (240). Alternatively, the insulating layer (250) is formed on the substrate (210) while covering at least a portion of the tab (230), the reinforcing layer (240) and / or the substrate (210). Alternatively, the insulating layer (250) is formed on the substrate (210) while covering the substrate (210), the tab (230) and / or the coating layer (220). Through this, for example, the insulating layer (250) can prevent the electrode (200) from being electrically or physically damaged by, for example, another electrode, a separator, an electrolyte or an external impact.

[0165] To this end, the insulating layer (250) includes, for example, an insulating material. Through this, the insulating layer (250) can insulate the portion covered by the insulating layer (250). For example, the insulating layer (250) prevents the tab (230) from being damaged by being electrically and / or physically connected to the outside.

[0166] At this time, the insulating material is a material having insulating properties, and includes at least one selected from the group consisting of, for example, polysulfone, polyurethane, polyamide, 6,6 nylon, polycarbonate (PC), polytetrafluoroethylene (PTFE), polymethyl methacrylate (PMMA), and polyethylene terephthalate (PET).

[0167] Alternatively, the insulating material may include a material that is resistant to heat and has a high melting point. For example, the insulating layer (250) includes an insulating material having a melting point of about 300° C. or higher. The insulating layer (320) includes at least one selected from the group consisting of, for example, polyimide (PI), Teflon, polyamide-imide (PAI), polyphenylene sulfide (PPS), and polyether ether ketone (PEEK).

[0168] Meanwhile, although not shown, the insulating layer (250) may further include an adhesive layer provided between the insulating layer (250) and the substrate (210), the coating layer (220), the reinforcing layer (230) and / or the tab (240). The adhesive layer may allow the insulating layer (250) to be fixed and / or adhered to the substrate (210), the coating layer (220), the reinforcing layer (230) and / or the tab (240).

[0169] For this purpose, the adhesive layer includes an adhesive material. The adhesive material includes at least one selected from the group consisting of, for example, polyurethane, epoxy resin, and polyolefin.

[0170] Meanwhile, FIG. 10 illustrates an example in which an insulating layer (250) is applied to an electrode (200) according to an embodiment shown in FIGS. 5 to 7. However, the insulating layer (250) is not limited to this example and may be applied to all or part of the electrodes (200) described in FIGS. 5 to 9, for example.

[0171] Through this configuration, the electrode (200) according to one embodiment provides a way to improve reliability and stability not only in physical aspects but also in electrical aspects.

[0172]

[0173] Below, experimental values ​​for an electrode (200) according to an embodiment are presented through a comparison between an embodiment and a comparative example. However, the embodiment described below is merely an example, and the electrode (200) according to an embodiment is not limited to the contents described below.

[0174] In the following [Table 1], the examples show examples in which the tensile strength of the reinforcing layer (240) according to one implementation example is at least 285 MPa. In addition, Comparative Examples 1 and 2 show examples in which the tensile strength of the reinforcing layer (240) is less than 285 MPa. The conditions for the examples and comparative examples 1 and 2 are as follows.

[0175] 1) Example

[0176] - Thickness: 13.5um

[0177] - Tensile strength: 306Mpa (error range ±15Mpa)

[0178] - Elongation: 3.4%

[0179] 2) Comparative Example 1

[0180] - Thickness: 13.5um

[0181] - Tensile strength: 274Mpa (error range ±15Mpa)

[0182] - Elongation: 3.9%

[0183] 3) Comparative Example 2

[0184] - Thickness: 13.5um

[0185] - Tensile strength: 274Mpa (error range ±15Mpa)

[0186] - Elongation: 2.8%

[0187] Current test example 1 Comparative example 2 Vertical crack occurrence (number / number) <12.5mΩ---<13.0mΩ0 / 160 / 30 / 5>13.0mΩ0 / 42 / 26 / 6

[0188] In [Table 1], the occurrence of vertical cracks (times / times) represents (the number of times vertical cracks occurred) / (the total number of experiments). In addition, in [Table 1], the current represents the size of the current (mΩ) flowing toward the electrode.

[0189] [Table 1] shows that the embodiment has a tensile strength of 306 MPa, and considering the margin of error, a minimum tensile strength of 291 MPa. That is, the embodiment has a tensile strength of 285 MPa (N / ㎟) or more. Regardless of the magnitude of the current flowing through the electrode, the embodiment did not produce vertical cracks. Since the embodiment has a tensile strength of 285 MPa or more, it can be seen that no cracks occurred.

[0190] In [Table 1], Comparative Example 1 has a tensile strength of 274 MPa, and considering the margin of error, a maximum tensile strength of 289 MPa. That is, Comparative Example 1 mostly has a tensile strength of less than 285 MPa (N / ㎟). In Comparative Example 1, longitudinal cracks occurred as the current flowing through the electrode increased. It can be seen that cracks occurred in Comparative Example 1 because it had a tensile strength of less than 285 MPa despite having a relatively high elongation.

[0191] In [Table 1], Comparative Example 2 has a tensile strength of 274 MPa, and considering the margin of error, a maximum tensile strength of 289 MPa. That is, Comparative Example 2 mostly has a tensile strength of less than 285 MPa (N / ㎟). In Comparative Example 2, longitudinal cracks occurred as the current flowing through the electrode increased. It can be seen that cracks occurred in Comparative Example 2 because it has a low elongation and a tensile strength of less than 285 MPa.

[0192] Through such experimental values, it can be seen that when the tensile strength of the reinforcing layer (240) is at least 285 MPa, cracks can be prevented from occurring in the electrode (200).

[0193]

[0194] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

Claims

1. Description; A coating layer provided on the first region which is part of the above description; A reinforcing layer provided on the second region, which is another part of the above description; and a tab provided on the second region and electrically connected to the substrate; electrode.

2. In paragraph 1, The above reinforcing layer is an electrode formed with the same thickness as the above coating layer.

3. In paragraph 1, An electrode in which the reinforcing layer is formed to a thickness thinner than the thickness of the coating layer.

4. In paragraph 1, The above reinforcing layer is an electrode comprising a conductive material.

5. In paragraph 1, An electrode in which the reinforcing layer comprises the same material as the material included in the substrate.

6. In paragraph 1, An electrode in which the reinforcing layer is formed to have a larger area than the tab in the direction toward the second region.

7. In paragraph 1, The above reinforcing layer is an electrode located between the substrate and the tab.

8. In paragraph 1, The above-mentioned electrode is provided with the reinforcing layer on one side of the second region and the tab on the other side of the second region.

9. In paragraph 1, The above description is an electrode formed with a tensile strength of 285 N / mm2 or more.

10. In paragraph 1, The above electrodes are, An electrode further comprising an insulating layer provided on the second region and including an insulating material while covering the tab.

11. An electrode assembly comprising a cathode, an anode, and a separator positioned between the cathode and the anode; and A case for storing the electrode assembly; including; At least one of the above cathode and anode, write; A coating layer provided on the first region which is part of the above description; A reinforcing layer provided on the second region, which is another part of the above description; and a tab provided on the second region and electrically connected to the substrate; Secondary battery.

12. In paragraph 11, A secondary battery, wherein the reinforcing layer is formed to a thickness less than or equal to the thickness of the coating layer.

13. In paragraph 11, A secondary battery, wherein the reinforcing layer comprises the same material as the material included in the substrate.

14. In paragraph 11, A secondary battery, wherein the reinforcing layer is formed to have a larger area than the tab in the direction toward the second region.

15. In paragraph 11, The reinforcing layer includes a first reinforcing layer provided between one side of the substrate and the tab; and a second reinforcing layer provided on the other side of the substrate. Secondary battery.

Images