Electrode for rechargeable battery

Abstract

An electrode for a rechargeable battery according to one embodiment of the present invention comprises: a substrate including a micro-pattern formed of a plurality of holes; and an active material layer formed on the substrate, wherein the plurality of holes have a depth that decreases from the center of the substrate toward the edge.

Description

Electrode for secondary battery

[0001] The present invention relates to electrodes, and more particularly to electrodes for secondary batteries.

[0002] Demand for secondary batteries as an energy source is increasing as technology develops and demand for mobile devices increases.

[0003] A secondary battery can be formed by placing electrodes on both sides of a separator and winding them in the form of a jelly roll, or by stacking sheet-shaped electrodes and separators, and then putting the electrode assembly together with an electrolyte into a case, and then sealing the opening of the case with a cap assembly.

[0004] In secondary batteries, reducing electrode fairness and electrical resistance is crucial for improving their performance. To this end, development is underway in various areas, including the composition and density of the active material layer. However, with respect to the conductive substrate, only thickness control remains a key area of ​​development.

[0005] Improving the electrical conductivity of metallic substrates may be important in the future as rapid charging becomes increasingly required, as it offers several advantages in terms of resistance, including reduced DC-IR.

[0006] However, the substrate is metallic and has a smooth surface. When special polymers are attached to the surface to improve processability, problems arise, such as reduced electrical conductivity. Furthermore, smooth substrates have limited physical contact with the active material layer, necessitating the use of large amounts of adhesive to increase bonding strength. Therefore, improvements in the contact between the substrate and the active material layer are needed.

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

[0008] The present invention provides an electrode for a secondary battery capable of increasing the bonding strength between an active material layer and a substrate without increasing the amount of adhesive.

[0009] An electrode for a secondary battery according to one embodiment of the present invention includes a substrate including a micro-pattern formed of a plurality of holes, and an active material layer formed on the substrate, wherein the depth of the plurality of holes decreases from the center of the substrate to the edge.

[0010] The above plurality of holes may have a diameter that decreases from the center of the substrate to the edge.

[0011] The above depth and diameter can be reduced at a constant rate.

[0012] The depth of the above hole may be 100 nm to 1,000 nm, and the diameter of the hole may be 10 μm to 100 μm.

[0013] The plane shape of the above hole may be circular.

[0014] The above-mentioned substrate includes an electrode active portion having an active material layer formed thereon and an electrode non-active portion having an exposed substrate without an active material layer formed thereon, and the active material layer can be formed on a micropattern.

[0015] The above description may include a first region in which a micro pattern is formed and a second region in which a micro pattern is not formed.

[0016] The above active material layer may have a different thickness at the portion protruding above the hole depending on the depth of the hole.

[0017] The above active material layer may have a thickness of a portion protruding above a hole located at the center thereof lower than a thickness of a portion protruding above a hole located at the edge thereof.

[0018] According to another embodiment of the present invention, an electrode for a secondary battery includes a substrate including a micro-pattern formed of a plurality of holes, and an active material layer formed on the substrate, wherein the plurality of holes have a depth that increases from the center of the substrate to the edge.

[0019] The above plurality of holes may have a diameter that decreases from the center of the substrate to the edge.

[0020] The above depth and diameter can be changed at a constant rate.

[0021] The depth of the above hole may be 100 nm to 1,000 nm, and the diameter of the hole may be 10 μm to 100 μm.

[0022] The plane shape of the above hole may be circular.

[0023] The above-mentioned substrate includes an electrode active portion on which the active material layer is formed and an electrode non-conductive portion on which the substrate is exposed because the active material layer is not formed, and the active material layer can be formed on a micropattern.

[0024] The above description may include a first region in which a micro pattern is formed and a second region in which a micro pattern is not formed.

[0025] The above active material layer can be formed with a uniform thickness over the entire substrate.

[0026] According to an embodiment of the present invention, by forming a micro pattern on the surface of a substrate, the bonding force between the substrate and the active material layer can be increased, thereby providing an electrode with improved electrical characteristics.

[0027] 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.

[0028] FIG. 1 is a plan view of a substrate included in a secondary battery according to one embodiment of the present invention.

[0029] Fig. 2 is a cross-sectional view taken along line II-II' of Fig. 1.

[0030] Figure 3 is a schematic cross-sectional view of an electrode according to one embodiment of the present invention.

[0031] Figure 4 is a plan view of a substrate included in an electrode for a secondary battery according to another embodiment of the present invention.

[0032] Figure 5 is a schematic cross-sectional view of an electrode for a secondary battery according to another embodiment of the present invention.

[0033] Figure 6 is a schematic exploded perspective view of a laminated electrode assembly according to one embodiment of the present invention.

[0034] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms or words used in this specification and claims should not be interpreted as limited to their typical or dictionary meanings, and should be interpreted with meanings and concepts that conform to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of a term to best explain his or her own invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as substitutes for them at the time of filing this application.

[0035] Additionally, when used herein, the terms "comprise", "include" and / or "comprising", "including" specify the presence of stated features, numbers, steps, operations, elements, elements and / or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, elements and / or groups thereof.

[0036] Additionally, to facilitate understanding of the invention, the attached drawings may not be drawn to scale and some components may be exaggerated in size. Furthermore, identical components may be assigned the same reference numbers in different embodiments.

[0037] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0038] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0039] For ease of explanation, spatially relative terms such as "beneath," "below," "lower," "above," "upper," and the like may be used herein to describe the relationship of one element or feature to another element(s) or feature(s) as depicted in the drawings. It will be understood that spatially relative positions encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if the device in the drawings is turned over, an element described as "beneath" or "below" another element would be understood to be "above" or "above" the other element. Thus, the term "beneath" can encompass both the above and below orientations.

[0040] Additionally, when a component is described as being "connected to" or "coupled to" another component, it should be understood that the components may be directly connected or coupled to one another, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through another component.

[0041] The terminology used herein is for the purpose of describing embodiments of the present disclosure and is not intended to be limiting of the present disclosure.

[0042] FIG. 1 is a plan view of a substrate included in a secondary battery according to one embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line II-II' of FIG. 1, and FIG. 3 is a schematic cross-sectional view of an electrode according to one embodiment of the present invention.

[0043] As shown in FIGS. 1 and 2, the substrate (70) according to one embodiment of the present invention can be used as a substrate or current collector of an electrode for a secondary battery as a metal thin film (or foil).

[0044] The substrate (70) may be made of copper or aluminum, etc. that can be used as an electrode, and may have a thickness of 5 µm to 20 µm.

[0045] A micro pattern may be formed on the surface of the substrate (70), and the substrate (70) may include a first region where the micro pattern (S) is formed and a second region where the micro pattern is not formed, and an active material layer may be formed in the first region where the micro pattern (S) is formed.

[0046] The micropattern (S) includes a plurality of holes (P) having a concave shape from the surface of the substrate (70), and the holes (P) may be formed with a constant size or arranged at a constant interval. The diameter (W) and depth (D) of the holes (P) are measured in micrometers, and the diameter (W) may be 10 μm to 100 μm, and the depth (D) of the holes may be 100 nm to 1,000 nm.

[0047] The spacing between adjacent holes (P) may be 50 μm or less, preferably 5 μm to 50 μm.

[0048] The micro pattern (S) can improve the current characteristics by increasing the bonding strength between the active material layer located on the surface of the substrate (70) and the substrate (70) during electrode manufacturing.

[0049] The size and shape of the hole (P) forming the micro pattern (S) may be different at the center and edge of the substrate (70). At this time, the center (C1) and edge (C2) of the substrate (70) may be the center and edge of the electrode, and the center and edge are relative positions.

[0050] The depth (D) of the hole (P) at the center (C1) may be deeper than the depth (D) of the hole (P) at the edge (C2), and the depth may gradually become shallower from the center (C1) to the edge (C2).

[0051] The electrode assembly exhibits greater gas generation at the center and greater expansion due to side reactions at the edges. Therefore, the depth of the hole at the center is deeper than at the edges, and the depth of the hole at the edges is shallower to even out the effects of expansion over the life of the electrode assembly.

[0052] Referring to Figure 3, when applying an active material, the active material flows into the pores of the substrate and fills the pores. Depending on the materials being mixed, the fluidity of the active material may vary. If the fluidity is almost zero, the active material may be applied at a nearly uniform thickness.

[0053] Since the active material is applied by filling the hole (P) as it is applied, if there is little fluidity, the amount of active material located in the hole may be greater in the center where the hole is relatively deep than in the edge. Accordingly, the total thickness (H1) of the active material layer including the substrate may be thinner in the center (H2) than in the edge (H3).

[0054] When charging and discharging a secondary battery, gas may be generated due to side reactions, and the center may swell more than the edges because more gas is generated.

[0055] In one embodiment of the present invention, the depth of the hole at the edge and center is made deeper at the center, thereby mitigating expansion due to gas and making the expansion rate at the center and edge uniform.

[0056] At this time, since the active material layer maintains a uniform thickness throughout, expansion due to the thickness of the active material layer can occur uniformly at the edges and the center.

[0057] In this way, in one embodiment of the present invention, the hole depth is made different at the center where gas generation is high and at the edge where gas generation is low, so that expansion is uniform throughout the active material layer.

[0058] Meanwhile, the edge of the substrate (70) is more prone to detachment of the active material forming the active material layer than the center.

[0059] In the present invention, the density of holes (P) can be increased to increase the contact area between the substrate (70) and the active material. The density of holes (P) can be increased by reducing the size (or diameter) of the holes (P), so that a relatively large number of holes (P) can be formed in the same area. That is, as the size of the holes (P) decreases, the number of holes (P) formed within the same area increases, and the contact area between the substrate (70) and the active material layer increases due to the active material filling the inside of the holes (P), thereby increasing the adhesiveness.

[0060] Again, referring to FIGS. 1 and 2, the planar shape of the hole (P) forming the micro-pattern (S) may be circular, and the diameter may decrease along with the depth of the hole (P) as it goes toward the edge.

[0061] Figure 4 is a plan view of a substrate included in an electrode for a secondary battery according to another embodiment of the present invention.

[0062] As illustrated in Fig. 4, a substrate (71) according to another embodiment of the present invention has a strip shape that is long in one direction. The substrate (71) can be used as an electrode substrate of a winding-type electrode assembly that is rolled around a winding axis (X).

[0063] The substrate (71) includes an electrode active portion and an electrode non-active portion, and a plurality of electrode non-active portions may be formed along the longitudinal direction (or winding direction) of the substrate (71). The electrode non-active portions formed in plurality may be folded toward the center of the electrode assembly after winding, and may be electrically connected to each other by welding.

[0064] Figure 5 is a schematic cross-sectional view of an electrode for a secondary battery according to another embodiment of the present invention.

[0065] According to another embodiment of the present invention, the substrate (72) may have a sheet as in FIG. 1.

[0066] Referring to FIG. 5, a micro pattern (S) is formed on the surface of the substrate (72), and the substrate (72) may include a first region where the micro pattern (S) is formed and a second region where the micro pattern is not formed, and an active material layer (82) may be formed in the first region where the micro pattern (S) is formed.

[0067] The micropattern (S) includes a plurality of holes (P) having a concave shape from the surface of the substrate (72), and the holes (P) may have a constant size or be arranged at constant intervals. The diameter (W) and depth (D) of the holes (P) are measured in micrometers, and the depth (D) may be 100 nm to 1,000 nm, and the diameter (W) of the holes may be 10 μm to 100 μm.

[0068] Unlike in FIGS. 2 and 3, the depth (D) of the hole (P) forming the micro-pattern (S) may gradually increase in depth from the center (C1) to the edge (C2). At this time, the diameter (W) of the hole may gradually decrease as in FIG. 1. Accordingly, the hole may have a narrower and deeper shape toward the edge (C2), and more holes may be formed at the edge compared to the center (C1), thereby increasing the hole density.

[0069] The viscosity of the active material layer (80) illustrated in FIG. 3 may have a viscosity greater than that of the active material layer illustrated in FIG. 5. Accordingly, the active material layer (80) illustrated in FIG. 3 does not flow after application and maintains the applied state, whereas the active material layer (82) illustrated in FIG. 5, which has a viscosity less than that of the active material layer illustrated in FIG. 3, has fluidity and can flow after application. Accordingly, the surface of the active material layer (82) positioned on the substrate can be flattened.

[0070] That is, since the active material of FIG. 5 has fluidity, the active material fills the hole after application, and the active material positioned above the hole moves to a concave or shallow area, thereby making the thickness of the active material layer (82) uniform across the entire substrate (72). Accordingly, the thickness (H1) of the active material layer (82) including the substrate (72) becomes uniform throughout.

[0071] In this way, throughout the substrate, the thickness of the active material layer including the substrate is almost the same at the center and the edge, but the depth of the hole at the center in FIG. 5 is shallower than the depth of the hole at the edge, so that the combined thickness of the active material layer inside the hole at the center and the active material layer formed on the substrate may be thinner than the combined thickness of the active material layer inside the hole at the edge and the active material layer formed on the substrate.

[0072] Since the expansion can increase in proportion to the thickness of the active material layer, in one embodiment of the present invention, the thickness at the center (C1) where the expansion occurs more than the edge (C2) is reduced and the thickness at the edge (C2) is increased so that the expansion occurs uniformly over the entire substrate.

[0073] The above description can be used as a description of a positive or negative electrode for a secondary battery electrode, and this will be described with reference to the drawings.

[0074] Figure 6 is a schematic exploded perspective view of a laminated assembly according to one embodiment of the present invention.

[0075] As illustrated in FIG. 6, an electrode assembly (101) according to one embodiment of the present invention includes a positive electrode (100), a negative electrode (200), and a separator (300) in the form of sheets, and is a laminated electrode assembly in which the positive electrode (100) and the negative electrode (200) are positioned on both sides with the separator (300) in between, and these are repeatedly positioned.

[0076] The positive electrode (100) includes an active portion (S1) of the positive electrode in which an active material layer is formed on a substrate made of an aluminum metal plate, and an uncoated portion (S2) of the positive electrode in which the substrate is exposed because no active material is applied on the substrate.

[0077] The substrate may be a substrate as shown in FIGS. 1 and 2, and includes a micro-pattern (S) formed of holes (P). The holes (P) may have a depth and diameter that decrease from the center to the edge.

[0078] Holes (P) are formed only in the electrode active portion (S2) and not in the electrode non-active portion (S1).

[0079] The active material forming the positive electrode active material layer may be a compound capable of reversible intercalation and deintercalation of lithium (lithiated intercalation compound). Specifically, one or more types of composite oxides of lithium and a metal selected from the group consisting of cobalt, manganese, nickel, and combinations thereof may be used. The content of the positive electrode active material may be 90% to 98% by weight based on the total weight of the positive electrode active material layer.

[0080] The positive electrode active material layer may further include a binder and a conductive material. In this case, the content of the binder and the conductive material may be 1 wt% to 5 wt%, respectively, based on the total weight of the positive electrode active material layer.

[0081] The binder helps the positive electrode active material particles adhere well to each other and also helps the positive electrode active material adhere well to the substrate, which is the current collector. Representative examples of the binder include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl 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, acrylated styrene butadiene rubber, epoxy resin, nylon, etc.

[0082] A conductive material is used to provide conductivity to an electrode, and any material that does not cause chemical changes and is electronically conductive can be used in the battery being constructed.

[0083] The cathode (200) includes a cathode electrode active portion (P1) in which an active material layer is formed on a substrate made of a superior metal thin plate having excellent conductivity, for example, copper (Cu), and a cathode electrode non-conductive portion (P2) in which the substrate is exposed because no active material is applied on the substrate.

[0084] The substrate may be a substrate as shown in FIGS. 1 and 2, and includes a micro-pattern (S) made of holes. The holes (P) may have a depth and diameter that decrease from the center (C1) to the edge (C2).

[0085] The hole (P) is formed only in the electrode active portion (P1) and not in the electrode non-active portion (P2).

[0086] The negative electrode active material layer may include a negative electrode active material, a conductive material, and a binder.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] The silicon-carbon composite may be a composite of silicon and amorphous carbon. In 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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. 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.

[0100] Again, referring to FIG. 5, the separator (300) may be a multilayer film of two or more layers of polyethylene, polypropylene, polyvinylidene fluoride, or these, and of course, a mixed multilayer film such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, a polypropylene / polyethylene / polypropylene three-layer separator, etc. may be used.

[0101] The separation membrane (300) 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.

[0102] The porous substrate may be a polymer membrane 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.

[0103] The organic material may include a polyvinylidene fluoride polymer or a (meth)acrylic polymer.

[0104] 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.

[0105] 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.

[0106] The separator (300) may be formed to be larger than the cathode (200) and the anode (100) and may protrude outward from the cathode (200) and the anode (100).

[0107] The electrode non-conductive portions (S1, P1) of the repeatedly laminated positive electrode (100) and negative electrode (200) are electrically connected to each other with the same polarity, and can be electrically connected to an external terminal. The electrode non-conductive portion (S1) of the positive electrode (100) and the electrode non-conductive portion (P2) of the negative electrode (200) may be spaced apart from each other and protrude in the same direction, but is not limited thereto, and may protrude in opposite directions.

[0108] The electrode assembly (101) can be used as a secondary battery by being housed in a square case (not shown) in the form of a pouch or can together with an electrolyte, and the electrolyte includes a non-aqueous organic solvent and a lithium salt.

[0109] The above non-aqueous organic solvent acts as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0110] 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.

[0111] 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).

[0112] 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.

[0113] 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.

[0114] The above non-aqueous organic solvents can be used alone or in combination of two or more.

[0115] 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.

[0116] 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).

[0117] Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the patent claims, the detailed description of the invention, and the attached drawings, and it is obvious that this also falls within the scope of the present invention.

[0118] - Explanation of symbols -

[0119] 70, 71, 72, 73: Description

[0120] 80: 82: Active material layer

[0121] 100: First electrode

[0122] 200: Second electrode

[0123] 300: Membrane

Claims

1. A substrate including a micro-pattern consisting of multiple holes; Active material layer formed on the above substrate Including, An electrode for a secondary battery in which the plurality of holes have a depth that becomes shallower from the center to the edge of the substrate.

2. In paragraph 1, An electrode for a secondary battery in which the above plurality of holes have a diameter that decreases from the center of the substrate to the edge.

3. In paragraph 1 or 2, An electrode for a secondary battery, wherein the depth and diameter are reduced at a constant rate.

4. In paragraph 1, An electrode for a secondary battery, wherein the depth of the hole is 100 nm to 1,000 nm.

5. In paragraph 1, An electrode for a secondary battery, wherein the diameter of the above hole is 10㎛ to 100㎛.

6. In paragraph 1, A secondary battery electrode having a circular plane shape of the above hole.

7. In paragraph 1, The above-mentioned substrate includes an electrode active portion where the active material layer is formed and an electrode non-active portion where the substrate is exposed because the active material layer is not formed. The above active material layer is an electrode for a secondary battery formed on the above micropattern.

8. In paragraph 1, The above-mentioned electrode for a secondary battery includes a first region in which the micro-pattern is formed and a second region in which the micro-pattern is not formed.

9. In paragraph 1, An electrode for a secondary battery, wherein the active material layer has a different thickness of a portion protruding above the hole depending on the depth of the hole.

10. In paragraph 9, An electrode for a secondary battery, wherein the thickness of the portion protruding above the hole located at the center of the active material layer is lower than the thickness of the portion protruding above the hole located at the edge.

11. A substrate comprising a micro-pattern consisting of multiple holes; Active material layer formed on the above substrate Including, An electrode for a secondary battery, wherein the plurality of holes have a depth that increases from the center of the substrate to the edge.

12. In paragraph 11, An electrode for a secondary battery in which the above plurality of holes have a diameter that decreases from the center of the substrate to the edge.

13. In paragraph 11 or 12, An electrode for a secondary battery in which the above depth and diameter change at a constant rate.

14. In paragraph 11, An electrode for a secondary battery, wherein the depth of the hole is 100 nm to 1,000 nm.

15. In paragraph 11, An electrode for a secondary battery, wherein the diameter of the above hole is 10㎛ to 100㎛.

16. In paragraph 1, A secondary battery electrode having a circular plane shape of the above hole.

17. In paragraph 11, The above-mentioned substrate includes an electrode active portion where the active material layer is formed and an electrode non-active portion where the substrate is exposed because the active material layer is not formed. The above active material layer is an electrode for a secondary battery formed on the above micropattern.

18. In paragraph 11, The above-mentioned electrode for a secondary battery includes a first region in which the micro-pattern is formed and a second region in which the micro-pattern is not formed.

19. In paragraph 11, An electrode for a secondary battery in which the above active material layer is formed with a uniform thickness over the entire substrate.

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