Electrode manufacturing apparatus and method, electrode sheet and manufacturing method therefor, and secondary battery

Abstract

Disclosed are an electrode manufacturing apparatus and method, an electrode sheet and a manufacturing method thereof, and a secondary battery including the electrode. The electrode manufacturing apparatus includes a platen roller having a surface roughness Ra of 0.25 [mu] m or more, the platen roller being configured to roll-press an electrode sheet.

Description

Technical Field

[0001] The present disclosure relates to an electrode manufacturing apparatus, an electrode manufacturing method, and a secondary battery including the electrodes manufactured thereby. Background Art

[0002] In recent years, with the rapid popularization of electronic devices using batteries (such as mobile phones, notebook computers and electric vehicles), the demand for high energy density and high capacity secondary batteries has rapidly increased. Therefore, people are actively conducting research and development to improve lithium secondary batteries.

[0003] Lithium secondary batteries include positive and negative electrodes containing active materials that allow the intercalation and deintercalation of lithium ions, and an electrolyte. The battery generates electricity through the oxidation and reduction of lithium ions when they are intercalated and deintercalated in the positive and negative electrodes.

[0004] The positive and / or negative electrodes included in a secondary battery may be referred to as "electrodes." Furthermore, the substrate on which the active material layer is disposed may be referred to as an electrode sheet. The electrode sheet is rolled to secure the active material layer to the substrate while improving impregnation and current transport.

[0005] The device that performs rolling on the electrode sheet may be referred to as a "pressing roller." The pressing roller is conventionally arranged as a pair of pressing rollers. The pressing roller presses the electrode sheet by applying force to the electrode sheet passing between the pair of pressing rollers.

[0006] The surface roughness of the pressing roller determines the surface roughness of the electrode sheet being pressed. The surface roughness of the electrode sheet affects the electrode's non-impregnation properties and / or the degree of salt precipitation. Therefore, in order to properly control the surface roughness of the electrode sheet, the surface roughness of the pressing roller must be controlled.

[0007] This section is intended only to provide a better understanding of the background of the disclosure and therefore may contain information that is not necessarily prior art. Summary of the Invention

[0008] One aspect of the present disclosure is to provide an electrode manufacturing apparatus including a press roller having high surface roughness.

[0009] Another aspect of the present disclosure is to provide an electrode having high surface roughness.

[0010] Another aspect of the present disclosure is to provide an electrode having a pattern formed thereon.

[0011] The above and other aspects and features of the present disclosure will become apparent from the following description of embodiments of the present disclosure.

[0012] According to one aspect of the present disclosure, an electrode manufacturing apparatus includes a pressing roller having a surface roughness Ra of 0.25 μm or greater, the pressing roller being configured to roll an electrode sheet.

[0013] According to another aspect of the present disclosure, an electrode manufacturing method includes rolling an electrode sheet by a pressing roller having a surface roughness Ra of 0.25 μm or more.

[0014] According to a further aspect of the present disclosure, a secondary battery includes: an electrode manufactured by an electrode manufacturing method; an electrode assembly including the electrode; and a case receiving the electrode assembly in the case.

[0015] One embodiment may provide an electrode manufacturing apparatus and an electrode manufacturing method, the electrode manufacturing apparatus including a press roller having high surface roughness at a short driving distance. For example, one embodiment may provide an electrode manufacturing apparatus and an electrode manufacturing method, the electrode manufacturing apparatus including a press roller having high surface roughness even after the press roller has been replaced.

[0016] An embodiment may provide an electrode manufacturing apparatus and an electrode control method that do not require controlling the dipping time of an electrode rolled by a press roller having a short driving distance.

[0017] One embodiment reduces the process time required to fabricate electrodes.

[0018] One embodiment provides an electrode having a small salt precipitation area when the electrode is rolled by a roller having a short driving distance.

[0019] One embodiment provides an electrode having a pattern formed on its surface.

[0020] However, aspects and features of the present disclosure are not limited to those described above, and other aspects and features not mentioned will be clearly understood by those skilled in the art from the detailed description given below. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings attached to this specification illustrate embodiments of the present disclosure and, together with the detailed description of the present disclosure, further describe aspects and features of the present disclosure. The present disclosure is not limited to the embodiments depicted in the accompanying drawings.

[0022] Figures 1 to 4 is a schematic cross-sectional view or perspective view of a lithium secondary battery according to an embodiment of the present disclosure;

[0023] Figure 5 is a schematic diagram of an electrode manufacturing apparatus according to an embodiment of the present disclosure;

[0024] Figure 6 A view showing a conventional electrode manufacturing apparatus and the surface of an electrode manufactured thereby;

[0025] Figure 7 is a flow chart illustrating a method for manufacturing an electrode according to an embodiment of the present disclosure;

[0026] Figure 8A and Figure 8B A graph depicting the surface roughness (Ra, Rz) of a press roller and an electrode used in a conventional electrode manufacturing apparatus and an electrode manufacturing apparatus according to an embodiment of the present disclosure;

[0027] Figure 9A and Figure 9B is a picture showing the surfaces of a conventional electrode sheet and an electrode sheet according to an embodiment of the present disclosure having similar surface roughness; and

[0028] Figure 10 The table compares the performance of a conventional electrode manufacturing apparatus and an electrode manufacturing apparatus according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0029] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, the following embodiments are provided by way of illustration, and the present disclosure is not limited to the illustrated embodiments.

[0030] When an element is referred to as being disposed (or located or positioned) “on” (or “under”) or “on” (or “under”) a component, it may mean that the element is placed in contact with the upper (or lower) surface of the component, and may also mean that another component may be interposed between the component and any arbitrary element disposed (or located or positioned) on (or under) the component.

[0031] Throughout the specification, unless otherwise specified, each element may be singular or plural. In addition, throughout the specification, when "A and / or B" is recited, it means A, B, or A and B, unless otherwise specified.

[0032] As used herein, "combinations thereof" may refer to mixtures, stacks, composites, copolymers, alloys, blends, and reaction products of the components.

[0033] Unless otherwise defined herein, particle size may refer to an average particle size. In addition, particle size refers to an average particle size (D50), which refers to the particle size corresponding to 50% volume in the cumulative volume distribution of particles. The average particle size can be measured by any method well known in the art, for example, by a particle size analyzer, a transmission electron microscope image, or a scanning electron microscope image. Alternatively, the average particle size (D50) can be measured by counting the number of particles within each particle size range using a device that uses a dynamic light scattering method to analyze data, and then calculating the average particle size (D50) based on the analyzed data. Alternatively, the average particle size (D50) can be measured by laser diffraction. More specifically, in the laser diffraction measurement, the target particles are dispersed in a dispersant, introduced into a commercially available laser diffraction particle analyzer (e.g., Microtrac MT 3000), and irradiated with ultrasonic waves of about 28kHz at a power of 60W, followed by calculating the average particle size (D50) corresponding to 50vol% volume in the cumulative volume distribution of particles in the measuring device.

[0034] Figures 1 to 4 is a schematic cross-sectional view or perspective view of a lithium secondary battery according to an embodiment of the present disclosure.

[0035] lithium secondary batteries

[0036] The lithium secondary battery may be referred to as a cylindrical secondary battery, a faceted secondary battery, a pouch-type secondary battery, a coin-type secondary battery, etc. based on its shape. Figures 1 to 4 is a schematic diagram of a lithium secondary battery according to an embodiment of the present disclosure. Figure 1 shows a cylindrical secondary battery, Figure 2 A multi-faceted secondary battery is shown, and Figure 3 and Figure 4 A pouch-type secondary battery is shown. Figures 1 to 4 , the lithium secondary battery 100 may include: an electrode assembly 40, wherein a separator 30 is interposed between a positive electrode 10 and a negative electrode 20; and a case 50, in which the electrode assembly 40 is housed. The positive electrode 10, the negative electrode 20, and the separator 30 may be embedded in an electrolyte (not shown). Figure 1 As shown in FIG. 1 , the lithium secondary battery 100 may include a sealing member 60 that seals the housing 50. Figure 2 As shown in FIG, the lithium secondary battery 100 may include a positive electrode lead tab 11, a positive electrode terminal 12, a negative electrode lead tab 21, and a negative electrode terminal 22. Figure 3 and Figure 4 As shown in FIG, the lithium secondary battery 100 may include electrode tabs 70, ie, a positive electrode tab 71 and a negative electrode tab 72, which serve as an electrical path for conducting current formed in the electrode assembly 40 to the outside of the battery.

[0037] cathode materials

[0038] As the positive electrode material, a compound that allows reversible intercalation and deintercalation of lithium (eg, a lithiated intercalation compound) may be used. In particular, the positive electrode material may be a composite oxide of lithium and at least one metal selected from cobalt, manganese, nickel, and combinations thereof.

[0039] The composite oxide may be a lithium transition metal composite oxide. In particular, the composite oxide may be lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate compound, cobalt-free nickel manganese oxide, or a combination thereof.

[0040] For example, the composite oxide may be a compound represented by any of the following molecular formulas: 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 Gb O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a 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); and Li a FePO4 (0.90≤a≤1.8). In these formulas, 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; and L 1 Mn, Al or a combination thereof.

[0041] In one embodiment, the positive electrode material may be a high-nickel content positive electrode material, comprising 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% to 99 mol% of nickel relative to 100 mol% of the metals other than lithium in the lithium transition metal composite oxide. High-nickel content positive electrode materials can achieve high capacity and are therefore suitable for use in high-capacity / high-density lithium secondary batteries.

[0042] Positive electrode 10

[0043] The positive electrode 10 of the lithium secondary battery 100 may include a positive electrode current collector and a positive electrode material layer formed on the positive electrode current collector. The positive electrode material layer includes a positive electrode material and may further include a binder and / or a conductive material. In one embodiment, the positive electrode 10 may further include a component capable of serving as a sacrificial positive electrode.

[0044] The positive electrode material may be present in an amount of 90 wt% to 99 wt% based on 100 wt% of the positive electrode material layer. Each of the binder and the conductive material may be present in an amount of 0.5 wt% to 5 wt% based on 100 wt% of the positive electrode material layer.

[0045] The binder is used to attach the positive electrode material particles to each other and to attach the positive electrode material to the positive electrode current collector. The binder may include, for example, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer including 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, and nylon, but the present disclosure is not limited to these examples.

[0046] Alternatively, the binder may comprise any binder that becomes fibrous under shear. For example, the binder may comprise polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polyolefin, or a mixture thereof.

[0047] The conductive material is used to impart conductivity to the electrodes and can be any conductive material that does not cause chemical changes in the battery cells. Conductive materials may include, for example, carbon materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials in the form of metal powders or metal fibers, including copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; and mixtures thereof.

[0048] The positive electrode current collector may be aluminum foil, but is not limited thereto.

[0049] Anode materials

[0050] The negative electrode material includes a material that allows for reversible intercalation / deintercalation of lithium ions, lithium metal, a lithium metal alloy, a material capable of being doped with and dedoped from lithium, or a transition metal oxide.

[0051] Materials that allow reversible intercalation / deintercalation of lithium ions may include carbon-based negative electrode materials, such as crystalline carbon, amorphous carbon, or combinations thereof. Crystalline carbon may include, for example, graphite, such as natural graphite or artificial graphite, in an amorphous, plate-like, flaky, spherical, or fibrous form. Amorphous carbon may include, for example, soft carbon, hard carbon, mesophase pitch carbide, and calcined coke.

[0052] The lithium metal alloy may be 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 may be used.

[0053] The material capable of being doped with lithium and dedoped therefrom may be a Si-based negative electrode material or a Sn-based negative electrode material. The Si-based negative electrode material may be silicon, a silicon-carbon composite, SiO x(0 < x ≤ 2), Si-Q alloy or a combination thereof. In the molecular formula Si-Q, Q is selected from alkali metals, alkaline earth metals, Group XIII elements, Group XIV elements (excluding Si), Group XV elements, Group XVI elements, transition metals, rare earth elements, and combinations thereof. The Sn-based anode material can be Sn, SiO x (where 0 < x ≤ 2, SnO2), Sn alloy or a combination thereof.

[0054] The silicon-carbon composite can be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite can be prepared in the form of silicon particles with an amorphous carbon coating formed on the surface. For example, the silicon-carbon composite can include secondary particles (cores) composed of primary silicon particles and an amorphous carbon coating (shells) formed on the surfaces of the secondary particles. Amorphous carbon can also be located between the primary silicon particles such that, for example, the primary silicon particles are covered with amorphous carbon. The secondary particles can be dispersed in an amorphous carbon matrix.

[0055] The silicon-carbon composite can further include crystalline carbon. For example, the silicon-carbon composite can include a core containing crystalline carbon and silicon particles and an amorphous carbon coating formed on the core.

[0056] The Si-based anode material or the Sn-based anode material can be used in combination with a carbon-based anode material.

[0057] Negative electrode 20

[0058] The anode 20 for the lithium secondary battery 100 can include an anode current collector and an anode material layer formed on the anode current collector. The anode material layer includes an anode material and can further include a binder and / or a conductive material. The anode material layer can include, for example, 90 wt% to 99 wt% of the anode material, 0.5 wt% to 5 wt% of the binder, and 0 wt% to 6 wt% of the conductive material.

[0059] The binder is used to attach the anode material particles to each other while attaching the anode material to the anode current collector. The binder can be a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof.

[0060] The non-aqueous binder can include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.

[0061] The aqueous binder can be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluorinated rubber, polyethylene oxide, polyvinyl pyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinyl pyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol and combinations thereof.

[0062] When an aqueous binder is used as a binder in the negative electrode material layer, a cellulose compound that can impart viscosity may be further included. The cellulose compound may be carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, or a mixture of alkali metal salts thereof. The alkali metal may be Na, K, or Li.

[0063] The dry binder may be a fibrous polymer material and may include, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or combinations thereof.

[0064] The conductive material is used to impart conductivity to the electrodes and can be any electronically conductive material that does not cause chemical changes in the battery cells. Specifically, the conductive material may include, for example, carbon materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials in the form of metal powders or metal fibers, including copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0065] 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 combinations thereof.

[0066] Electrolyte (not shown)

[0067] The electrolyte used in the lithium secondary battery 100 includes a non-aqueous organic solvent and a lithium salt.

[0068] The non-aqueous organic solvent acts as a medium through which ions participating in the electrochemical reaction of the battery cell can move. The non-aqueous organic solvent can be a carbonate solvent, an ester solvent, an ether solvent, a ketone solvent, an alcohol solvent, an aprotic solvent, or a combination thereof.

[0069] Carbonate solvents may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), ethylmethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC).

[0070] The ester solvents may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanoic acid lactone, mevalonolactone, valerolactone, caprolactone, and the like.

[0071] Ether solvents may include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and tetrahydrofuran. In addition, ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol and isopropanol, etc., and non-amphoteric solvents may include nitriles such as R-CN (wherein 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, etc., and sulfolane, etc.

[0072] The nonaqueous organic solvent may be used alone or as a mixture thereof.

[0073] When the carbonate solvent is used, a mixture of cyclic carbonate and linear carbonate can be used. The cyclic carbonate and linear carbonate can be mixed in a volume ratio of 1:1 to 1:9.

[0074] Lithium salts are soluble in organic solvents and act as a source of lithium ions in batteries, ensuring the basic operation of lithium secondary batteries by promoting the transfer of lithium ions between the positive electrode and the negative electrode. Examples of lithium salts may 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) (wherein x and y are integers of 1 to 20), at least one of lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalato)phosphate (LiDFBOP) and lithium bis(oxalato)borate (LiBOB).

[0075] Diaphragm 30

[0076] Depending on the type of lithium secondary battery 100, a separator 30 may be interposed between the positive electrode 10 and the negative electrode 20. For such a separator 30, polyethylene, polypropylene, polyvinylidene fluoride, or two or more layers thereof and mixed layers such as a polyethylene / polypropylene double-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, and a polyethylene / polyethylene / polypropylene three-layer separator may be used.

[0077] The separator 30 may include a porous substrate and a coating layer including an organic material, an inorganic material, or a combination thereof on one or both surfaces of the porous substrate.

[0078] The porous substrate may be a polymer layer formed of a polymer or copolymer thereof or a mixture thereof selected from the group consisting of polyolefins (such as polyethylene, polypropylene, etc.), polyesters (such as polyethylene terephthalate and polybutylene terephthalate, etc.), polyacetals, polyamides, polyimides, polycarbonates, polyetherketones, polyaryletherketones, polyetherimides, polyamideimides, polybenzimidazoles, polyethersulfones, polyphenylene oxides, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fibers, and polytetrafluoroethylene.

[0079] The organic material may include a polyvinylidene fluoride polymer or a (meth)acrylic polymer.

[0080] The inorganic material may include inorganic particles selected from the group consisting of Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof, but the present disclosure is not limited to these examples.

[0081] The organic material and the inorganic material may exist in a mixed state in one coating layer, or may exist in the form of a stacked structure of a coating layer including an organic material and a coating layer including an inorganic material.

[0082] refer to Figures 1 to 4 The secondary battery 100 according to the embodiment includes an electrode assembly 40 and a case 50 accommodating the electrode assembly 40. The electrode assembly 40 includes a positive electrode 10, a negative electrode 20, and a separator 30 interposed between the positive electrode 10 and the negative electrode 20. Here, the positive electrode 10 and / or the negative electrode 20 will be referred to as "electrode".

[0083] An electrode according to an embodiment includes an electrode sheet including a substrate and an active material layer formed on the substrate.

[0084] For example, the substrate is formed by a (current) current collector. The substrate can be formed based on, for example, the type of electrode. When the electrode is the positive electrode 10, the substrate includes, for example, aluminum. When the electrode is the negative electrode 20, the substrate includes, for example, at least one of 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. Examples of the substrate are the same or similar to those described above.

[0085] The active material layer can be formed as a self-supporting film with a dry layer and / or as a slurry with a wet layer. The active material layer includes an active material. The active material can be determined, for example, by the type of electrode. Examples and References of Active Materials Figures 1 to 4The active material layer may further include a binder and / or a coating material. Examples of the binder and / or coating material are the same as or similar to those described above.

[0086] This electrode is formed by rolling an electrode sheet. Rolling the electrode sheet determines the degree of adhesion between the substrate and the active material layer, the degree of salt precipitation, the degree of electrolyte impregnation, and the charge / discharge efficiency. Therefore, by properly controlling the rolling operation of the electrode sheet, a high-efficiency electrode can be produced. Electrodes with high efficiency include, for example, electrodes with appropriate surface roughness, impregnation time, salt precipitation area, and pattern presence.

[0087] Hereinafter, the electrode manufacturing apparatus 200 according to an embodiment of the present disclosure will be described in detail.

[0088] Figure 5 Schematic diagram of an electrode manufacturing device according to an embodiment of the present disclosure.

[0089] The electrode manufacturing apparatus 200 according to an embodiment rolls the electrode sheet 310. Through this rolling operation, the electrode manufacturing apparatus 200 can efficiently manufacture electrodes and / or can reduce the process time for manufacturing electrodes.

[0090] The electrode manufacturing apparatus 200 includes a pressing roller 210. The pressing roller 210 includes, for example, a pair of pressing rollers, namely, a first roller 211 and a second roller 212. The first roller 211 and the second roller 212 are spaced apart from each other. The pressing roller 210 applies a force to the electrode sheet 310 passing through the gap between the first roller 211 and the second roller 212 to press the electrode sheet 310.

[0091] The pressure applied to the electrode sheet 310 is adjusted by controlling the gap between the first roller 211 and the second roller 212. For example, to increase the pressure applied to the electrode sheet 310, the gap between the first roller 211 and the second roller 212 may be reduced. Alternatively, to reduce the pressure applied to the electrode sheet 310, the first roller 211 and the second roller 212 may be moved further apart.

[0092] The straight line connecting the center of the first roller 211 and the center of the second roller 212 may be perpendicular to the travel direction P of the electrode sheet 310. However, in other embodiments, in an arrangement for a subsequent process applied to the electrode sheet 310, the straight line connecting the center of the first roller 212 and the center of the second roller 212 may not be perpendicular to the travel direction P of the electrode sheet 310.

[0093] The first roller 211 and the second roller 212 rotate in opposite directions. For example, the first roller 211 rotates in a first direction a, and the second roller 212 rotates in a second direction b, where the second direction b is opposite to the first direction a. For example, when the first direction a is counterclockwise, the second direction b is clockwise, and vice versa. Here, in the portion where the first roller 211 and the second roller 212 contact the electrode sheet 310, the first direction a and the second direction b may be the same as the travel direction P of the electrode sheet 310.

[0094] In addition, the electrode manufacturing apparatus 200 may further include a conveying unit (not shown). The conveying unit conveys the electrode sheet 310. For example, the conveying unit conveys the electrode sheet 310 from an external device toward the electrode manufacturing apparatus 200. The conveying unit may further convey the electrode sheet 310 between components within the electrode manufacturing apparatus 200. Furthermore, the conveying unit may convey the electrode sheet 310 from the electrode manufacturing apparatus 200 toward an external device.

[0095] In an embodiment, a conveying unit conveys the pre-rolled electrode sheet 311 to the gap between the first roller 211 and the second roller 212. The conveying unit may, for example, be in the form of a roller spaced apart from the pressing roller 210. However, the conveying unit is not limited thereto and may have any form capable of conveying the electrode sheet 310, such as a conveyor belt. Furthermore, after the electrode sheet 312 is rolled by the pressing roller 210, the conveying unit may convey the electrode sheet 312 from the pressing roller 210.

[0096] For this reason, the electrode manufacturing apparatus 200 can manufacture an electrode by rolling the electrode sheet 310 with the pressing roller 210. Here, when a force (e.g., a shear force) is applied to the electrode sheet 310, the surface of the pressing roller 210 is worn. For this reason, the surface of the pressing roller 210 may have a step between its used portion and the unused portion. In this case, problems may arise in which the electrode sheet 310 breaks during the rolling process and / or the thickness of the manufactured electrode is uneven. Therefore, the pressing roller 210 must be replaced regularly. However, when the pressing roller 210 is replaced, there is a problem in which the surface roughness Ra of the pressing roller 210 changes. Referring to Figure 6 Describe the problem.

[0097] Figure 6 This is a view showing a conventional electrode manufacturing apparatus and the surface of an electrode manufactured thereby. Figure 6 , (A1) illustrates a first press roller (hereinafter referred to as "first conventional press roller") included in a conventional electrode manufacturing apparatus. Here, for example, the first conventional press roller has just been installed (replacing the previous press roller), and the first conventional press roller has a driving distance (i.e., a distance traveled by a point on the press roller surface) of 10 km or less. The first conventional press roller has a surface roughness of, for example, approximately 0.1 μm.

[0098] exist Figure 6, (A2) shows the surface morphology of the electrode manufactured by the first conventional pressing roller (hereinafter referred to as the "first conventional electrode"). Figure 6 (A2) shows that the surface of the first conventional electrode is glossy.

[0099] exist Figure 6 In FIG, (A3) shows the surface morphology of the first conventional electrode. Figure 6 As can be seen from (A3), the first conventional electrode has an increased surface area of ​​84.92%.

[0100] exist Figure 6 , (B1) shows a second press roller (hereinafter referred to as "second conventional press roller") included in the conventional electrode manufacturing apparatus. The second conventional press roller has a driving distance of approximately 4500 km and a surface roughness of, for example, approximately 0.7 μm. Here, the second conventional press roller has a surface roughness of approximately 0.1 μm at a driving distance of 10 km.

[0101] exist Figure 6 , (B2) shows the surface morphology of the electrode manufactured by the second conventional pressing roller (hereinafter referred to as the "second conventional electrode"). Figure 6 As shown in (B2), it can be seen that the surface of the second conventional electrode is not glossy.

[0102] exist Figure 6 In FIG. 1 , (B3) shows the surface morphology of the second conventional electrode. Figure 6 As can be seen from (B3), the second conventional electrode has an increased surface area of ​​379.24%.

[0103] from Figure 6 It can be seen that when the surface roughness of the electrode (e.g., the first conventional electrode) is low when rolled with a roller having a low surface roughness (e.g., the first conventional roller). The electrode having a low surface roughness has a low impregnation rate, and the secondary battery including such an electrode undergoes insufficient impregnation at a given impregnation time. As a result, quality degradation problems such as salt precipitation may occur.

[0104] To address these issues, electrodes with low surface roughness are traditionally impregnated with electrolyte for a longer period of time to ensure sufficient impregnation. However, this process is inefficient. For example, due to the increased impregnation time immediately following roller replacement, process time also increases. Furthermore, due to the additional steps required, process costs also increase.

[0105] Next, an apparatus and method for producing an electrode with high quality while reducing a process time for controlling impregnation will be described.

[0106] Figure 7 FIG. 1 is a flow chart illustrating a method for manufacturing an electrode according to an embodiment of the present disclosure.

[0107] As above Figure 5 As described in the embodiment, the electrode manufacturing apparatus 200 according to the embodiment includes a pressing roller 210. In the following description of the electrode manufacturing apparatus 200, the components related to the pressing roller 210 will be omitted. Figure 5 The same or similar features as those in the electrode manufacturing apparatus 200 described in .

[0108] The pressure roller 210 may include a coating on its surface to prevent wear of the pressure roller 210 and increase the life of the pressure roller 210. The coating may include, for example, tungsten carbide and DLC. In addition, the pressure roller 210 coated with the coating may be subjected to processing (including, for example, polishing) to maintain its original shape.

[0109] The press roller 210 according to one embodiment requires minimal machining to increase its initial roughness. For this purpose, for example, the electrode manufacturing apparatus 200 according to this embodiment includes a press roller 210 having a surface roughness Ra of 0.25 μm or greater. Here, the surface roughness Ra is a value measured when the press roller 210 has a driving distance of 10 km or less. Within this range, the press roller 210 requires minimal machining, thereby increasing its initial roughness.

[0110] In other embodiments, the electrode manufacturing apparatus 200 may include a press roller 210 having a surface roughness Ra of 0.30 μm or greater. Here, the surface roughness Ra is a value measured when the press roller 210 has a driving distance of 10 km or less. Within this range, the press roller 210 requires less machining, thereby increasing the initial roughness of the press roller 210.

[0111] On the other hand, the press roller 210 may be subjected to too little machining. In this case, the press roller 210 cannot maintain its original shape. Therefore, the press roller 210 according to an embodiment of the present disclosure may include a press roller 210 having a surface roughness Ra of 0.7 μm or less. Here, the surface roughness Ra is a value measured when the press roller 210 has a driving distance of 10 km or less.

[0112] In example embodiments, the pressing roller 210 may have a surface roughness Ra of 0.25 μm to 0.7 μm. In other embodiments, the pressing roller 210 may have a surface roughness Ra of 0.25 μm to 0.65 μm, a surface roughness Ra of 0.30 μm to 0.70 μm, a surface roughness Ra of 0.30 μm to 0.65 μm, a surface roughness Ra of 0.25 μm to 0.60 μm, a surface roughness Ra of 0.25 μm to 0.55 μm, a surface roughness Ra of 0.30 μm to 0.60 μm, or a surface roughness Ra of 0.30 μm to 0.55 μm.

[0113] As such, the electrode manufacturing apparatus 200 according to this embodiment can ensure that the electrode sheet 310 has a high surface roughness Ra even immediately after the press roller 210 is installed, by using the press roller 210 having a surface roughness Ra of 0.25 μm or more at a driving distance of less than 10 km. Furthermore, the electrode manufacturing apparatus 200 according to this embodiment can improve the non-impregnation property of the electrode sheet 310 subjected to roller pressing and / or can reduce the salt precipitation area.

[0114] like Figure 7 As shown in FIG, the electrode manufacturing method according to this embodiment can be implemented by an electrode manufacturing device 200 .

[0115] The electrode manufacturing method according to the present embodiment includes a step (S101) of rolling an electrode sheet by a pressing roller having a surface roughness Ra of 0.25 μm or more. The surface roughness Ra refers to the surface roughness of the pressing roller 210 when the pressing roller 210 has a driving distance of 10 km or less. In other embodiments, the electrode manufacturing method may include rolling the electrode sheet by a pressing roller having a surface roughness Ra of 0.25 μm to 0.70 μm, rolling the electrode sheet by a pressing roller having a surface roughness Ra of 0.30 μm or less, or rolling the electrode sheet by a pressing roller having a surface roughness Ra of 0.30 μm to 0.7 μm.

[0116] The electrode sheet is prepared by forming an active material layer on a current collector, wherein the active material layer includes a composite oxide of lithium and at least one metal selected from cobalt, manganese, nickel and a combination thereof.

[0117] The electrode manufacturing method according to one embodiment may further include a step (S102) of impregnating the rolled electrode sheet 312 with an electrolyte by injecting an electrolyte into the rolled electrode sheet 312. Here, the step of impregnating the electrode sheet 312 includes impregnating the rolled electrode sheet 312 with an electrolyte for less than 3 hours. As described above, even if rolling is performed immediately after replacing the pressing roller 210, the electrode manufacturing method can ensure that the electrode sheet 312 has a high surface roughness Ra. Therefore, the electrode manufacturing method can reduce the impregnation time for the electrode sheet 312. For example, the electrode sheet 312 can be fully impregnated with the electrolyte within a time of less than 3 hours. Alternatively, for example, the electrode sheet 312 can be fully impregnated with the electrolyte within a time of less than 2.9 hours, can be fully impregnated within a time of less than 2.8 hours, can be fully impregnated within a time of less than 2.7 hours, or can be fully impregnated with the electrolyte within a time of less than 2.6 hours.

[0118] The electrode manufacturing apparatus 200 and the electrode manufacturing method have been described above, which are capable of efficiently manufacturing electrodes even after replacing the pressing roller 210. In the following description, the excellent performance of the electrode manufactured by the electrode manufacturing apparatus 200 and / or the electrode manufacturing method according to the embodiment and the electrode according to one embodiment will be described.

[0119] Figure 8A and Figure 8B Graph depicting the surface roughness (Ra, Rz) of a press roller and an electrode used in a conventional electrode manufacturing apparatus and an electrode manufacturing apparatus according to an embodiment of the present disclosure.

[0120] Figure 8A The surface roughness Ra of the pressing roller and the electrode (or electrode sheet) according to the related art and an embodiment of the present disclosure is shown. Here, the surface roughness Ra represents the centerline average surface roughness measured along the centerline of the surface. Figure 8A The conventional press roller (Comparative Example_press roller) has a surface roughness Ra of 0.1 μm or less at a driving distance of less than 10 km. The electrode (Comparative Example_electrode sheet) rolled by the conventional press roller has a surface roughness Ra of 0.1 μm or less. The press roller 210 (Example_press roller) according to the present embodiment has a surface roughness Ra of 0.30 μm at a driving distance of less than 10 km. The electrode (Example_electrode sheet) rolled by the press roller 210 according to the present embodiment has a surface roughness Ra of 0.4 μm or less.

[0121] exist Figure 8B , the surface roughness Rz of the pressing roller and the electrode (or electrode sheet) according to the related art and an embodiment of the present disclosure is shown. Here, the surface roughness Rz represents the ten-point average surface roughness measured at ten points on the surface of the pressing roller and the electrode. The conventional pressing roller (comparative example_pressing roller) has a surface roughness Rz of less than 1.0 μm at a driving distance of less than 10 km. The electrode (comparative example_electrode sheet) rolled by the conventional pressing roller has a surface roughness Rz of less than 1.0 μm. The pressing roller 210 (example_pressing roller) according to the present embodiment has a surface roughness Rz of more than 2.0 μm at a driving distance of less than 10 km. The electrode (example_electrode sheet) rolled by the pressing roller 210 according to the present embodiment has a surface roughness Rz of about 3.2 μm or more.

[0122] from Figure 8A and Figure 8B It can be seen that the electrode manufactured by the electrode manufacturing apparatus 200 according to the embodiment of the present disclosure, which includes the press roller 210 with increased initial roughness, has increased surface roughness (Ra, Rz) compared to the conventional electrode.

[0123] Figure 9A and Figure 9B 1 is a photograph showing surfaces of a conventional electrode sheet and an electrode sheet according to an embodiment of the present disclosure having similar surface roughness.

[0124] Figure 9A Shown by reference Figure 8A and / or Figure 8BThe surface of the electrode sheet is rolled by the pressing roller 210 according to the embodiment of the present disclosure. The pressing roller 210 has a driving distance of 10 km or less and an initial surface roughness Ra of 0.30 μm.

[0125] from Figure 9A As can be seen, the electrodes according to this embodiment have a predetermined pattern. The predetermined pattern is, for example, formed side by side in one direction. In other embodiments, the predetermined pattern may be formed, for example, in a mesh shape. The mesh shape is formed, for example, by a first straight line formed at a first angle and a second straight line formed at a second angle and intersecting the first straight line. Here, the first angle and the second angle are different from each other. Alternatively, the predetermined pattern includes, for example, a pattern having grooves formed at regular intervals.

[0126] The electrode according to the present embodiment has a surface roughness Ra of 0.35 μm or more, as measured on the surface of the electrode sheet subjected to rolling. The electrode according to the present embodiment has a salt precipitation area of ​​0.20% or less, as measured on the surface of the electrode sheet subjected to rolling.

[0127] Figure 9B Shown by reference Figure 5 The surface of the electrode sheet rolled by the conventional pressing roller described above. Here, the pressing roller 210 has a driving distance of about 4000 km and an initial surface roughness Ra of 0.7 μm or more. Figure 9B It can be seen that the conventional electrode has a randomly roughened surface that does not form a regular pattern.

[0128] If you can from Figure 9A and / or Figure 9B It can be seen that even when the pressure roller 210 has a short driving distance, the electrode manufacturing apparatus and / or electrode manufacturing method according to the embodiment of the present disclosure can manufacture an electrode having a high surface roughness Ra. In addition, the electrode manufacturing apparatus and / or electrode manufacturing method according to the embodiment of the present disclosure can manufacture an electrode having a pattern on its surface. Therefore, the electrode manufactured according to the embodiment of the present disclosure and the secondary battery 100 including the electrode can be manufactured by an efficient process and have improved charge / discharge performance.

[0129] Figure 10 The table compares the performance of a conventional electrode manufacturing apparatus and an electrode manufacturing apparatus according to an embodiment of the present disclosure. Comparative Examples 1 to 5 are electrodes manufactured by an electrode manufacturing apparatus including a press roller having an initial surface roughness Ra of approximately 0.1 μm.

[0130] In Comparative Example 1, the press roller used to press the electrode sheet had a drive distance of 791 km. In Comparative Example 2, the press roller had a drive distance of 938 km. In Comparative Example 3, the press roller had a drive distance in the range of 794 km to 806 km. In Comparative Example 4, the press roller had a drive distance of 844 km to 868 km. In Comparative Example 5, the press roller had a drive distance of 1116 km to 1132 km.

[0131] exist Figure 10 In the example shown in , an electrode is manufactured by a press roller 210 according to an embodiment of the present disclosure. In this example, the press roller 210 has a driving distance of 10 km or less and a surface roughness Ra of 0.30 μm.

[0132] from Figure 10 It can be seen that although the driving distance of the pressure roller is much shorter than that of the pressure rollers of Comparative Examples 1 to 5, the example electrode has a similar and / or shorter immersion time. It can also be seen that the example electrode has a salt precipitation area (%) similar to and / or smaller than that of the electrodes of Comparative Examples 1 and 2. In particular, it can be seen that at a driving distance of more than 800 km, the example electrode has a salt precipitation area similar to that of the electrode of Comparative Examples 4 or 5, and / or at a driving distance of more than 700 km, has an immersion time similar to that of the electrodes of Comparative Examples 2 to 4. Therefore, it can be seen that the electrode manufacturing apparatus 200 according to the present embodiment includes a pressure roller 210 having an increased initial surface roughness Ra, thereby providing similar or better effects than a pressure roller having a driving distance of more than 700 km even immediately after replacement.

[0133] Further, as referenced Figure 9A 、 Figure 9B and Figure 10 For example, it can be seen that the electrode manufactured using the pressing roller 210 has excellent performance, with a salt precipitation area of ​​0.20% or less and / or an immersion time of 3 hours or less. Furthermore, the electrode according to an embodiment of the present disclosure has a predetermined pattern on its surface, thereby providing further improved performance.

[0134] Although the present disclosure has been described with reference to some embodiments and the accompanying drawings illustrating various aspects thereof, the present disclosure is not limited thereto, and various modifications and variations may occur to those skilled in the art to which the present disclosure pertains.

[0135] <Reference Sign List>

[0136] 200: Electrode manufacturing equipment

[0137] 210: Press roller

Claims

1. An electrode manufacturing device comprising: The pressing roller has a surface roughness Ra of 0.25 μm or more and is configured to press the electrode sheet. 2 . The electrode manufacturing apparatus according to claim 1 , wherein the press roller has a surface roughness Ra of 0.25 μm or more at a driving distance of 10 km or less. 3 . The electrode manufacturing apparatus according to claim 1 , wherein the pressing roller is configured to form a predetermined pattern in the electrode sheet. 4 . The electrode manufacturing apparatus according to claim 1 , wherein the pressing roller is configured to press the electrode sheet so that the electrode sheet is provided with a surface roughness Ra of 0.35 μm or more.

5. An electrode sheet manufactured by the electrode manufacturing apparatus according to any one of claims 1 to 4, wherein the electrode sheet comprises: current collector; as well as An active material layer is formed on at least one surface of the current collector and includes an active material including a composite oxide of lithium and at least one metal selected from the group consisting of cobalt, manganese, nickel, and combinations thereof. 6 . A method for manufacturing an electrode sheet using the electrode manufacturing apparatus according to claim 1 , wherein the electrode sheet is impregnated with the electrolyte for 3 hours or less.

7. A method for manufacturing an electrode, comprising: The electrode sheet was rolled by a pressing roller having a surface roughness Ra of 0.25 μm or more. 8 . The electrode manufacturing method according to claim 7 , wherein the press roller has a surface roughness Ra of 0.25 μm or more at a driving distance of 10 km or less. 9 . The electrode manufacturing method according to claim 7 , further comprising impregnating the rolled electrode sheet with an electrolyte for 3 hours or less.

10. The electrode manufacturing method according to any one of claims 7 to 9, further comprising forming the electrode sheet by forming an active material layer including an active material on a current collector, the active material including a composite oxide of lithium and at least one of cobalt, manganese, nickel, and combinations thereof.

11. A secondary battery comprising: An electrode assembly comprising an electrode manufactured by the electrode manufacturing method according to claim 7; as well as A housing in which the electrode assembly is received. 12 . The secondary battery according to claim 11 , wherein the electrode has a predetermined pattern on a surface of the electrode. 13 . The secondary battery according to claim 11 , wherein the electrode has a surface roughness Ra of 0.35 μm or more. 14 . The secondary battery according to claim 11 , wherein the electrode has a salt precipitation area of ​​0.20% or less. 15 . The secondary battery according to claim 11 , wherein the electrode assembly comprises a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and the electrode comprises the positive electrode.

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