Dry electrode, method for manufacturing the same, and secondary battery including the same

Abstract

This invention provides a dry electrode, a method for manufacturing the dry electrode, and a secondary battery including the dry electrode. The dry electrode comprises an electrode active material, a binder, and a polyether-based polymer compound. The polyether-based polymer compound is present in an amount of 0.1% to 15% by weight, based on 100% by weight of the total dry electrode content. This composition improves process efficiency by enabling dry manufacturing and enhances electrode performance through structural stability.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of Korean Patent Application No. 10-2025-0017338, filed on February 11, 2025 with the Korean Intellectual Property Office, entitled "Dry electrode, method for manufacturing the dry electrode and secondary battery including the dry electrode", the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to a dry electrode, a method for manufacturing the dry electrode, and a secondary battery including the dry electrode. Background Technology

[0004] To improve the energy density of secondary batteries, research is underway on how to fabricate thicker electrodes. However, existing wet-process-based electrode fabrication techniques have limitations in achieving greater thickness. Therefore, dry-process-based electrode fabrication techniques have attracted attention, as these techniques allow for the formation of thicker electrodes. Furthermore, since these techniques do not use solvents, they eliminate the need for a separate solvent drying process, making them more economical and environmentally friendly, while also improving process efficiency.

[0005] Polytetrafluoroethylene (PTFE) is a typical binder used in dry processes, and it may undergo electrochemical decomposition near 0.5V (vs. Li / Li+). This is because PTFE has a large number of fluorine atoms attached to carbon in its polymer molecular structure, making it unstable. Therefore, a technology capable of addressing this problem is needed. Summary of the Invention

[0006] The present invention aims to provide a dry electrode in which the decomposition of binder during charge and discharge can be significantly suppressed.

[0007] Furthermore, the present invention aims to provide a method for manufacturing dry electrodes using only a dry process.

[0008] Furthermore, the present invention aims to provide a secondary battery with a significantly improved initial coulombic efficiency (ICE).

[0009] Some embodiments of the present invention provide a dry electrode comprising an electrode active material, a binder, and a polyether-based polymer compound, wherein the polyether-based polymer compound is present in an amount of 0.1% to 15% by weight, based on 100% by weight of the total dry electrode content.

[0010] The polyether-based polymer compound may be present in an amount of 2% to 5% by weight, based on 100% by weight of the total dry electrode content.

[0011] Polyether-based polymer compounds can have melting points of 120°C or lower.

[0012] Polyether-based polymer compounds may include polyalkylene glycols.

[0013] Polyalkylene glycols may include at least one selected from polyethylene glycol, polypropylene glycol, and copolymers containing polyethylene glycol and polypropylene glycol.

[0014] Polyether-based polymer compounds can have a weight-average molecular weight ranging from 100 g / mol to 70,000 g / mol.

[0015] Alternatively, polyether-based polymer compounds can have a weight-average molecular weight of 400 g / mol to 25,000 g / mol.

[0016] At least a portion of the surface of the electrode active material may be coated with a polyether-based polymer compound.

[0017] Electrode active materials can include positive electrode active materials or negative electrode active materials.

[0018] The binder may include one or more different types of resins or polymers, such as fluorinated resins, aromatic resins (e.g., polystyrene), polyacrylates, and polyimides. More specifically, suitable binders may include, for example, at least one selected from polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), cellulose, styrene-butadiene rubber (SBR), polyimide (PI), polyacrylic acid (PAA), basic polyacrylate, polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), and combinations thereof.

[0019] The dry electrode may further contain conductive material.

[0020] Some embodiments of the present invention provide a method for manufacturing a dry electrode, the method comprising: preparing a mixture comprising an electrode active material, a binder and a polyether-based polymer compound, and rolling the mixture to manufacture a dry electrode, wherein the polyether-based polymer compound is present in an amount of 0.1% to 15% by weight, based on 100% by weight of the total content of the mixture.

[0021] The mixture may be solvent-free.

[0022] Polyether-based polymer compounds may include polyalkylene glycols.

[0023] Polyalkylene glycols may include at least one selected from polyethylene glycol, polypropylene glycol, and copolymers containing polyethylene glycol and polypropylene glycol.

[0024] Some embodiments of the present invention also provide a secondary battery comprising a positive electrode, a negative electrode and an electrolyte, wherein one or more of the positive or negative electrode is a dry electrode as described in any of the above embodiments.

[0025] The dry electrode according to the present invention can significantly suppress the decomposition of the binder during charge and discharge.

[0026] According to the method for manufacturing the dry electrode of the present invention, a dry electrode capable of significantly suppressing the decomposition of the binder during charge and discharge can be manufactured solely through a dry process. According to the present invention, a thickened electrode with improved quality can be manufactured in a time- and cost-efficient manner.

[0027] Secondary cells including the dry electrode according to the invention can have significantly improved initial coulombic efficiency.

[0028] In some embodiments, a dry electrode is provided. The electrode comprises an electrode active material; a binder; and a polyether-based polymer compound in an amount of about 0.1% to 15% by weight, based on 100% by weight of the total dry electrode content, wherein the polyether-based polymer compound is a copolymer comprising polyethylene glycol (PEG) and polypropylene glycol (PPG), and the mass ratio of PEG to PPG in the copolymer is about 1.9:1 to 9:1.

[0029] The copolymer of PEG and PPG can be a block copolymer with PEG and PPG as repeating segments, and the weight-average molecular weight of the polyether-based polymer compound can be from about 100 g / mol to 70,000 g / mol.

[0030] The dry electrode may further comprise a carbon-based conductive material selected from natural graphite, artificial graphite, carbon black, carbon fibers, carbon nanotubes, graphene, graphene oxide, and activated carbon. The conductive material may be present in an amount of approximately 0.1% to 10% by weight, based on 100% of the total dry electrode content.

[0031] In some embodiments, a secondary battery is provided. The battery includes a positive electrode, a negative electrode, and an electrolyte. The negative electrode is the aforementioned dry electrode. When the negative electrode is assembled with metallic lithium as a counter electrode to form a half-cell, and charged at 0.1C to a cutoff voltage of 10mV under constant current / constant voltage conditions, and then charged at a constant voltage of 10mV until the current drops to 0.05C, the half-cell exhibits an initial coulombic efficiency of at least 81%. Attached Figure Description

[0032] The foregoing and other aspects, features, and advantages, as well as the detailed description of the following embodiments, will be better understood when read in conjunction with the accompanying drawings. However, the invention is not intended to be limited to the details shown in the figures, and various modifications and structural changes may be made therein without departing from the spirit of the invention and the scope and equivalence of the claims. The same reference numerals and symbols denote the same elements in the various figures.

[0033] Figure 1 A graph showing the initial coulombic efficiency of half-cells including the dry electrodes of Examples 1 to 7 and Comparative Example 1.

[0034] Figure 2 Voltage-specific capacity curves for half-cells containing dry electrodes from Examples 1 to 7 and Comparative Example 1. Detailed Implementation

[0035] The embodiments described in this specification can be modified in various other forms, and are not limited to the embodiments described below according to various aspects of the art. The various aspects provided are intended to make the description of the invention more thorough and to fully convey the scope of the invention to those skilled in the art.

[0036] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms “a,” “an,” and “described” are intended to include the plural forms as well, unless the context clearly indicates otherwise. These terms are intended only to distinguish one component from another, and do not limit the nature, order, or sequence of the constituent components. It will be further understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of the stated features, values, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, values, steps, operations, elements, components, and / or combinations thereof. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. Throughout the specification, unless expressly stated to the contrary, the term “comprising” and variations such as “including” or “comprising” should be understood to imply the inclusion of the stated elements but not exclude any other elements. Furthermore, the terms “unit,” “device,” “component,” and “module” described in the specification mean a unit for performing at least one function and operation and can be implemented by hardware components or software components and combinations thereof.

[0037] Unless otherwise stated or obvious from the context, the term “about” as used herein is understood to mean within the normal tolerance range in the field, such as within two standard deviations of the mean. “About” can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless the context clearly indicates otherwise, all numerical values ​​provided herein are modified by the term “about”.

[0038] Furthermore, the numerical ranges used in this specification include all values ​​between the lower and upper limits, all values ​​logically derived within the shape and breadth of the defined range, all double-limited values, and all possible combinations of the lower and upper limits of different defined numerical ranges. Unless specifically defined in this specification, values ​​that may exceed the defined numerical range due to experimental error or rounding are also included within the defined numerical range.

[0039] In this specification, when a layer, film, region, plate, etc., is described as being "on top of" or "above" another component, this includes both cases where it is directly on the other component and cases where the other component is inserted between them.

[0040] In this specification, polyether-based polymer compounds refer to polymer compounds in which polyether bonds (-O-) are repeating units.

[0041] In this specification, polyalkylene glycols refer to polymer compounds obtained by polymerizing epoxides. Epoxides refer to compounds having an epoxide structure, such as ethylene oxide, propylene oxide, and butylene oxide. Exemplary epoxides include, for example, ethylene oxide, 1,2-epoxide, 2,3-epoxide, 1,2-epoxide, 2-methyl-1,2-epoxide, 2,3-epoxide, tetrahydrofuran, epichlorohydrin, hexane oxide, glycidyl ethers (such as bisphenol A diglycidyl ether), or other polymerizable ethylene oxides. In some aspects, C2-C 16 - Epoxides may be preferred. Epoxides are also characterized as cyclic ethers having the general formula (CH2)nO(CH2)n, where each n is the same or different positive integer.

[0042] The term "electrode active material" in this article refers to a material capable of electrochemically absorbing and releasing lithium ions or other charged ions.

[0043] The term "block copolymer" as used herein refers to a copolymer in which two or more different polymer chains or blocks (e.g., PEG blocks and PPG blocks) with different compositions are covalently bonded end-to-end.

[0044] The term "half-cell" in this article refers to an electrochemical cell that contains only one electrode under study (e.g., a negative electrode) and a reference electrode or counter electrode (e.g., lithium metal).

[0045] The term “initial coulombic efficiency” (ICE) in this article refers to the ratio (expressed as a percentage) of the first discharge capacity to the first charge capacity during a charge-discharge test.

[0046] As used herein, a "dry electrode" refers to an electrode that is formed or manufactured without the use of any solvent (organic or aqueous) in the mixing, bonding, or coating steps.

[0047] As described herein, dry electrode technology or similar terms can refer to a manufacturing process that is substantially solvent-free or solvent-free (without solvent), such as using a dry mixture of battery components (active materials, binders, and conductive additives) to manufacture electrodes, rather than, for example, a solvent-dependent wet slurry method. In some respects, dry electrode coating processes can apply a dry (solvent-free or very low-solvent) mixture of active materials and conductive additives to an electrode substrate.

[0048] Various embodiments of the present invention relate to a dry electrode capable of significantly suppressing binder decomposition during charge and discharge, a method for manufacturing the dry electrode, and a secondary battery including the dry electrode.

[0049] The dry electrode according to one embodiment of the present invention comprises an electrode active material, a binder, and a polyether-based polymer compound. The polyether-based polymer compound may be present in an amount from 0.1% to 15% by weight, based on 100% by weight of the total dry electrode content.

[0050] Dry electrodes containing 0.1% to 15% by weight of a polyether-based polymer compound can significantly suppress binder decomposition during charge and discharge. Specifically, when the dry electrode does not contain a polyether-based polymer compound, the binder may react with lithium ions and decompose during charge and discharge at 1V (vs. Li / Li+) or below. This decomposition of the binder may reduce the number of lithium ions participating in the charge and discharge of the secondary battery, thus adversely affecting the capacity characteristics of the secondary battery. On the other hand, when the dry electrode contains 0.1% to 15% by weight of a polyether-based polymer compound, the polyether-based polymer compound may disrupt the electron transport path between the electrode active material and the binder. Therefore, the electrochemical decomposition reaction of the binder may be kinetically suppressed, potentially reducing the number of irreversibly consumed lithium ions. Secondary batteries including such dry electrodes can significantly improve the initial coulombic efficiency, thereby achieving high capacity and high energy density.

[0051] At least a portion or the entire surface of the electrode active material may be coated with a polyether-based polymer compound. This can more effectively interrupt the electron transport path between the electrode active material and the binder, thereby further suppressing the decomposition of the binder during charge and discharge.

[0052] At least a portion or the entire surface of the electrode active material and the binder can be coated with a polyether-based polymer compound. This can interrupt the electron transport path between the electrode active material and the binder even more effectively, thereby significantly suppressing the decomposition of the binder during charge and discharge.

[0053] The polyether-based polymer compound may be present in amounts ranging from 0.1% to 15% by weight, 0.5% to 15% by weight, or 0.5% to 10% by weight, based on 100% of the total dry electrode content. When the content of the polyether-based polymer compound is within the above range, the decomposition of the binder during charge and discharge can be significantly suppressed.

[0054] Preferably, the polyether-based polymer compound may be present in an amount of 1.8% to 10% by weight, based on 100% by weight of the total dry electrode content. When the content of the polyether-based polymer compound is within the above range, the decomposition of the binder during charge and discharge can be more significantly suppressed.

[0055] More preferably, the polyether-based polymer compound may be present in an amount of 2% to 5% by weight, based on 100% by weight of the total dry electrode content. When the content of the polyether-based polymer compound is within this range, the decomposition of the binder during charge and discharge can be suppressed even more significantly.

[0056] The polyether-based polymer compound can have a lower melting point than the binder, and can have a melting point of 120°C or lower. In various exemplary embodiments, the melting point of the polyether-based polymer compound can be 100°C or lower, 80°C or lower, or 60°C or lower, with a lower limit of, for example, 10°C or higher, or 20°C or higher. For example, the melting point of the polyether-based polymer compound can be 10°C to 100°C, 20°C to 80°C, or 20°C to 60°C. This allows the electrode active material to be coated more uniformly with the polyether-based polymer compound, thereby more significantly suppressing the decomposition of the binder during charge and discharge. The melting point of the polyether-based polymer compound or the binder can be measured using differential scanning calorimetry (DSC).

[0057] Polyether-based polymer compounds may include polyalkylene glycols. In various exemplary embodiments, polyalkylene glycols may include at least one selected from polyethylene glycol (PEG), polypropylene glycol (PPG), and copolymers comprising PEG and PPG.

[0058] When the polyether-based polymer compound includes polypropylene glycol, copolymers containing polyethylene glycol and polypropylene glycol, or combinations thereof, the degradation of the adhesive can be suppressed more significantly.

[0059] Copolymers containing polyethylene glycol and polypropylene glycol use PEG and PPG as repeating units and can be random copolymers or block copolymers. Examples of block copolymers can include linear structures such as poly(ethylene glycol-b-propylene glycol), poly(ethylene glycol-b-propylene glycol-b-ethylene glycol), or poly(propylene glycol-b-ethylene glycol-b-propylene glycol). The PEG / PPG ratio of copolymers containing PEG and PPG can be from 1:9 to 9:1 or from 6:4 to 9:1 by mass ratio of repeating units. However, there are no particular limitations on the PEG / PPG ratio, as long as the resulting copolymer effectively inhibits binder decomposition when used to coat electrode active materials.

[0060] Polyether-based polymer compounds can have a weight-average molecular weight ranging from 100 g / mol to 70,000 g / mol. The weight-average molecular weight can be the polyethylene glycol equivalent weight-average molecular weight determined by gel permeation chromatography. When the weight-average molecular weight of the polyether-based polymer compound is within this range, it can more significantly suppress the decomposition of the binder during charge and discharge. However, when the weight-average molecular weight of the polyether-based polymer compound is less than 100 g / mol, its viscosity and mechanical strength may be too low to suppress binder decomposition. When the weight-average molecular weight of the polyether-based polymer compound exceeds 70,000 g / mol, the viscosity may become too high, leading to uneven coating on the electrode active material. Furthermore, excessively high viscosity may hinder the movement of lithium ions within the electrode, resulting in increased electrode resistance and decreased battery capacity.

[0061] In a preferred embodiment, the polyether-based polymer compound may have a weight-average molecular weight of 400 g / mol to 25000 g / mol, 450 g / mol to 21000 g / mol, or 450 g / mol to 20000 g / mol. When the weight-average molecular weight of the polyether-based polymer compound is within the above range, the decomposition of the binder during charge and discharge can be more significantly suppressed. More preferably, the polyether-based polymer compound may include polypropylene glycol having the above-mentioned weight-average molecular weight, copolymers comprising polyethylene glycol and polypropylene glycol having the above-mentioned weight-average molecular weight, or combinations thereof. Even more preferably, the polyether-based polymer compound may be polypropylene glycol with a weight-average molecular weight of 400 g / mol to 5000 g / mol or 450 g / mol to 3000 g / mol, copolymers comprising polyethylene glycol and polypropylene glycol with a weight-average molecular weight of 5500 g / mol to 15000 g / mol, or combinations thereof.

[0062] Electrode active materials can include positive electrode active materials or negative electrode active materials.

[0063] The positive electrode active material is not particularly limited, but may include, for example, an oxide active material or a sulfide active material.

[0064] The oxide active material may include: layered rock salt type active materials such as LiCoO2, LiMnO2, LiNiO2, LiVO2 or Li 1+x Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O2; spinel type active materials such as LiMn2O4 or Li(Ni 0.5 Mn 1.5 )O4; inverse spinel type active materials such as LiNiVO4 or LiCoVO4; olivine type active materials such as LiFePO4, LiMnPO4, LiCoPO4 or LiNiPO4; silicon-containing active materials such as Li2FeSiO4 or Li2MnSiO4; layered rock salt type active materials in which part of the transition metal is replaced by a different metal, such as LiNi 0.8 Co( 0.2-x )Al x O2(0 < x < 0.2); spinel type active materials in which part of the transition metal is replaced by a different metal, such as Li 1+x Mn 2-x-y M y O4 (where M is at least one selected from Al, Mg, Co, Fe, Ni and Zn, and 0 < x + y < 2); or lithium titanate such as Li4Ti5O 12 , but is not limited thereto.

[0065] The sulfide active material may include Chevrel copper, iron sulfide, cobalt sulfide, nickel sulfide, etc.

[0066] The negative electrode active material is not particularly limited, but may include, for example, a carbon-based active material, a metal-based active material, or a combination thereof. In various exemplary embodiments, the negative electrode active material may include at least one selected from graphite, silicon, silicon oxide, silicon-carbon composite materials, and combinations thereof. The silicon-carbon composite material may be a composite material in which a carbon-based material is coated on the surface of silicon secondary particles formed by silicon agglomeration. The carbon-based material may include at least one selected from natural graphite, artificial graphite, amorphous carbon, and combinations thereof.

[0067] Based on 100% by weight of the total dry electrode content, the electrode active material may be present in an amount of 50% to 99.8% by weight. When the content of the electrode active material is less than 50% by weight, an insufficient electron transfer path may not be formed between the electrode active materials, and thus the charge-discharge capacity of the secondary battery including the electrode may be reduced.

[0068] According to one embodiment, a binder present in the dry electrode can improve the cohesion of the constituent materials within the dry electrode. The binder may include at least one selected from polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), cellulose, styrene-butadiene rubber (SBR), polyimide (PI), polyacrylic acid (PAA), basic polyacrylate, polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), and combinations thereof. In various exemplary embodiments, the binder may include polytetrafluoroethylene (PTFE).

[0069] The binder may be present in amounts ranging from 0.1% to 49.9% by weight, based on 100% by weight of the total dry electrode content. When the binder content exceeds 49.9% by weight, the binder may hinder the movement of lithium ions within the electrode, leading to increased electrode resistance and decreased battery capacity.

[0070] In one embodiment, the dry electrode may comprise 50% to 99.8% by weight of electrode active material, 0.1% to 49.9% by weight of binder, and 0.1% to 15% by weight of polyether-based polymer compound. Alternatively, the dry electrode may comprise 50% to 98% by weight of electrode active material, 0.1% to 48% by weight of binder, and 0.1% to 15% by weight of polyether-based polymer compound.

[0071] For example, a dry electrode may comprise 50% to 98% by weight of electrode active material, 0.1% to 48% by weight of binder, and 1.8% to 10% by weight of polyether-based polymer compound. Alternatively, a dry electrode may comprise 70% to 98% by weight of electrode active material, 0.1% to 28% by weight of binder, and 1.8% to 10% by weight of polyether-based polymer compound.

[0072] The dry electrode may further contain conductive material to improve its conductivity.

[0073] Conductive materials may include carbon-based conductive materials. Carbon-based conductive materials may include at least one selected from natural graphite, artificial graphite, carbon black, carbon fibers, carbon nanotubes, graphene, graphene oxide, and activated carbon. However, carbon-based conductive materials are not particularly limited to these, as long as they are intended to improve the conductivity of the electrode.

[0074] The conductive material may be present in an amount of 0.1 wt% to 10 wt% or 0.1 wt% to 5 wt% of 100 wt% of the total dry electrode content. When the content of the conductive material is below the above range, a smooth electron transport channel may not be formed within the electrode due to insufficient conductive material. Therefore, the battery capacity may be reduced compared to containing a sufficient amount of conductive material. On the other hand, when the content of the conductive material exceeds the above range, excessive conductive material may hinder the movement of lithium ions within the electrode, leading to increased electrode resistance and decreased battery capacity. For example, the dry electrode according to one embodiment may contain 50 wt% to 99.7 wt% of electrode active material, 0.1 wt% to 49.8 wt% of binder, 0.1 wt% to 15 wt% of polyether-based polymer compound, and 0.1 wt% to 10 wt% of conductive material.

[0075] In one embodiment, the dry electrode may further include a current collector. When the dry electrode further includes a current collector, the dry electrode may include the current collector and an electrode film disposed on at least one surface of the current collector, wherein the electrode film may include an electrode active material, a binder, and a polyether-based polymer compound. The electrode film may further include a conductive material. The electrode active material, binder, polyether-based polymer compound, and conductive material are the same as described above, and therefore a detailed description of them will be omitted.

[0076] A method for manufacturing a dry electrode according to one embodiment of the present invention, the method comprising: (S1) preparing a mixture comprising an electrode active material, a binder, and a polyether-based polymer compound; and (S2) rolling the mixture to manufacture a dry electrode. The polyether-based polymer compound may be present in an amount from 0.1% to 15% by weight, based on 100% by weight of the total content of the mixture.

[0077] The dry electrode according to one embodiment of the present invention can significantly suppress the decomposition of the binder during charge and discharge. The dry electrode designed according to the present invention can be manufactured by adding a polyether-based polymer compound in an amount of 0.1% to 15% by weight during the manufacturing process of the dry electrode, offering advantages in terms of process cost and time.

[0078] According to a method for manufacturing a dry electrode, during the process of manufacturing the dry electrode by preparing a mixture of electrode active material, binder, and polyether-based polymer compound and rolling the mixture, at least a portion of the surface of the electrode active material can be coated with the polyether-based polymer compound. Therefore, the electron transport path between the electrode active material and the binder can be interrupted more effectively, thereby further suppressing the decomposition of the binder during charge and discharge.

[0079] S1 is a method for preparing a mixture of electrode active material, binder, and polyether-based polymer compound. A conductive material may be further included to prepare the mixture. The electrode active material, binder, polyether-based polymer compound, and conductive material are the same as described above, therefore a detailed description of them will be omitted.

[0080] Polyether-based polymer compounds may include polyalkylene glycols. In various exemplary embodiments, polyalkylene glycols may include at least one selected from polyethylene glycol (PEG), polypropylene glycol (PPG), and copolymers comprising PEG and PPG.

[0081] S1 may include preparing a composition for manufacturing a dry electrode, the composition comprising an electrode active material, a binder and a polyether-based polymer compound, and a mixture thereof for manufacturing a dry electrode.

[0082] Compositions for manufacturing dry electrodes may comprise 50% to 99.8% by weight of electrode active material, 0.1% to 49.9% by weight of binder, and 0.1% to 15% by weight of polyether-based polymer compound. In various exemplary embodiments, compositions for manufacturing dry electrodes may comprise 50% to 98% by weight of electrode active material, 0.1% to 48% by weight of binder, and 0.1% to 15% by weight of polyether-based polymer compound.

[0083] For example, a composition for manufacturing a dry electrode may comprise 50% to 98% by weight of an electrode active material, 0.1% to 48% by weight of a binder, and 1.8% to 10% by weight of a polyether-based polymer compound. Alternatively, a composition for manufacturing a dry electrode may comprise 70% to 98% by weight of an electrode active material, 0.1% to 28% by weight of a binder, and 0.1% to 10% by weight of a polyether-based polymer compound.

[0084] The composition for manufacturing a dry electrode may further comprise a conductive material. The conductive material may be present in an amount of 0.1% to 10% by weight or 0.1% to 5% by weight, based on 100% by weight of the total content of the composition for manufacturing a dry electrode. For example, the composition for manufacturing a dry electrode according to one embodiment may comprise 50% to 99.7% by weight of electrode active material, 0.1% to 49.8% by weight of binder, 0.1% to 15% by weight of polyether-based polymer compound, and 0.1% to 10% by weight of conductive material.

[0085] In S1, the mixture may not contain a solvent. Therefore, by manufacturing the electrode under dry conditions without using a solvent, defects such as pinholes or cracks in the electrode film can be prevented. Furthermore, this process eliminates the need for drying the solvent.

[0086] In S1, mixing is not limited to a specific method; as long as the materials present in the mixture can be uniformly dispersed, mixing can be carried out in various ways. For example, in S1, the materials to be present in the mixture can be introduced into a mixing device such as a mixer, mill, blender, or ultrasonic mixer for mixing.

[0087] In S1, mixing can be carried out at temperatures ranging from 10°C to 120°C or from 25°C to 100°C.

[0088] S2 is a process of rolling the mixture to manufacture a dry electrode. S2 may include rolling the mixture to manufacture a dry electrode film and attaching the dry electrode film to at least one surface of the current collector. The rolling of the mixture may be performed using methods known in the art. For example, the dry electrode may be manufactured by applying pressure using rollers, a press, or similar equipment.

[0089] A secondary battery according to one embodiment of the present invention includes a positive electrode, a negative electrode, and an electrolyte, wherein one or more of the positive or negative electrode can be a dry electrode as described above.

[0090] By incorporating dry electrodes that effectively suppress binder decomposition during charge and discharge, secondary batteries exhibit significantly improved initial coulombic efficiency. Therefore, secondary batteries can achieve high capacity and high energy density.

[0091] The secondary battery can exhibit an initial coulombic efficiency of at least 81%. The initial coulombic efficiency can be at least 84%, at least 85%, at least 86%, or at least 87%.

[0092] For example, the secondary battery can be a lithium secondary battery, which may include lithium-ion batteries or lithium metal batteries.

[0093] The secondary battery may include the aforementioned dry electrode as the negative electrode. As a representative example of a secondary battery, a lithium secondary battery can be considered. The positive electrode can be any material capable of reversible lithium-ion insertion and extraction. The positive electrode may, for example, include: lithium oxides with a layered structure, such as LiMO2 (where M is one or more transition metals selected from Co and Ni) or Li... α Ni x Co y M zO2 (where 1≤α≤1.2, α is a real number, 0.2≤x≤0.9, x is a real number, 0.01≤y≤0.5, y is a real number, 0.01≤z≤0.5, z is a real number, x+y+z=1, and M is one or more elements selected from Mg, Sr, Ti, Zr, V, Nb, Ta, Mo, W, B, Al, Fe, Cr, Mn, and Ce); lithium oxides with spinel structures, such as Li4Mn5O 12 Lithium phosphate-based materials with an olivine structure, such as LiMPO4 (where M is Fe, Co, or Mn); or mixtures thereof. However, the cathode is not limited to these.

[0094] Electrolytes can include liquid electrolytes, solid electrolytes, or combinations thereof, and any electrolyte commonly used in secondary batteries can be used without restriction. Therefore, a detailed description thereof is omitted.

[0095] The embodiments and experimental examples will be described and illustrated in detail below. However, the embodiments and experimental examples provided below are for illustrative purposes only, and the techniques described in this specification are not limited thereto.

[0096] <Example 1>

[0097] A mixture was prepared by blending 94.5 wt% graphite (as the negative electrode active material), 2 wt% vapor-grown carbon fiber (VGCF) (as a conductive additive), 3 wt% polytetrafluoroethylene (PTFE) (as a binder), and 0.5 wt% polypropylene glycol (PPG, Mw: 2,000 g / mol) (as a polyether-based polymer compound). The mixed negative electrode solid components were then processed into a film using a three-roll mill to form a dry electrode.

[0098] <Examples 2 to 17>

[0099] The dry electrode was manufactured in the same manner as in Example 1, except that the contents of graphite, VGCF, PTFE and polyether-based polymer compounds and the types of polyether-based polymer compounds were adjusted as listed in Table 1 below.

[0100] <Comparative Example 1>

[0101] The dry electrode was manufactured in the same manner as in Example 1, except that no polyether-based polymer compound was used and the graphite content was adjusted as listed in Table 1 below.

[0102] <Experimental Example> Initial Coulomb Efficiency Measurement

[0103] Half-cells were assembled using the dry electrodes prepared in Examples 1 to 17 and Comparative Example 1 as negative electrodes and lithium metal as the counter electrode. The assembled half-cells were charged with a constant current (CC) of 0.1C until the voltage reached 10mV, and then charged with a constant voltage (CV) until the charging current reached 0.05C, completing the first charge cycle. The half-cells were then discharged with a constant current (CC) of 0.1C until the voltage reached 1.5V, and the discharge capacity of the first cycle was measured. The initial coulombic efficiency (ICE) was determined based on the charge and discharge capacities of the first cycle, and the results are shown in Table 1.

[0104] Initial coulombic efficiency = (Discharge capacity in the first cycle / Charge capacity in the first cycle) × 100

[0105] [Table 1]

[0106]

[0107]

[0108] 1) A1: PEG-PPG-PEG (PEG: 30% by weight)

[0109] 2) A2: PEG-PPG-PEG (PEG: 82.5% by weight)

[0110] Figure 1 A graph illustrating the initial coulombic efficiency based on the content of the polyether-based polymer compound used. This graph shows the initial coulombic efficiency of half-cells including the dry electrodes of Examples 1 to 7 and Comparative Example 1.

[0111] Refer to Table 1 and Figure 1 It can be confirmed that in Comparative Example 1, which does not contain a polyether-based polymer compound, the initial coulombic efficiency is lower than that of Examples 1 to 17. On the other hand, in Examples 1 to 17, which contain a polyether-based polymer compound, it is confirmed that the initial coulombic efficiency is at least 4.5% higher and at most 17.2% higher than that of Comparative Example 1.

[0112] Figure 2 Voltage-specific capacity curves for half-cells including dry electrodes from Examples 1 to 7 and Comparative Example 1 are shown. Figure 2 As shown, it can be confirmed that the curve profiles of Examples 1 to 7, which contain polyether-based polymer compounds, are around 0.5V (vs. Li / Li+) and differ from the curve profile of Comparative Example 1. Furthermore, although... Figure 2Not shown in the figures, but similar curve profiles were observed in Examples 8 to 17 at around 0.5V (vs. Li / Li+). These results indicate that the addition of the polyether-based polymer compound mitigates the decomposition of PTFE near 0.5V (vs. Li / Li+).

[0113] The invention described above is not limited to the aspects described herein and in the accompanying drawings. It will be apparent to those skilled in the art that various substitutions, alterations, and modifications can be made, which, although not illustrated herein, remain within the spirit and scope of the invention. Therefore, the scope of the invention is not defined by the detailed description, but by the claims and their equivalents, and all variations within the scope of the claims and their equivalents should be understood to exist within the invention.

Claims

1. A dry electrode comprising: Electrode active materials; Adhesives; and Polyether-based polymer compounds, in, The polyether-based polymer compound is present in an amount of 0.1% to 15% by weight, based on 100% by weight of the total dry electrode content.

2. The dry electrode according to claim 1, wherein, The polyether-based polymer compound is present in an amount of 2% to 5% by weight, based on 100% by weight of the total dry electrode content.

3. The dry electrode according to claim 1, wherein, The polyether-based polymer compound has a melting point of 120°C or lower.

4. The dry electrode according to claim 1, wherein, The polyether-based polymer compound includes polyalkylene glycol.

5. The dry electrode according to claim 4, wherein, The polyalkylene glycol includes at least one selected from polyethylene glycol, polypropylene glycol, and copolymers comprising polyethylene glycol and polypropylene glycol.

6. The dry electrode according to claim 1, wherein, The polyether-based polymer compound has a weight-average molecular weight of 100 g / mol to 70,000 g / mol.

7. The dry electrode according to claim 6, wherein, The polyether-based polymer compound has a weight-average molecular weight of 400 g / mol to 25000 g / mol.

8. The dry electrode according to claim 1, wherein, At least a portion of the surface of the electrode active material is coated with a polyether-based polymer compound.

9. The dry electrode according to claim 1, wherein, The electrode active material includes positive electrode active material or negative electrode active material.

10. The dry electrode according to claim 1, wherein, The adhesive comprises at least one selected from polytetrafluoroethylene, polyvinylidene fluoride, cellulose, styrene-butadiene rubber, polyimide, polyacrylic acid, basic polyacrylate, polymethyl methacrylate, polyacrylonitrile, and combinations thereof.

11. The dry electrode according to claim 1, wherein the dry electrode further comprises a conductive material.

12. A method for manufacturing a dry electrode, the method comprising: Prepare a mixture comprising electrode active material, binder and polyether-based polymer compound; as well as Rolling the mixture to manufacture dry electrodes The polyether-based polymer compound is present in an amount of 0.1% to 15% by weight, based on 100% by weight of the total content of the mixture.

13. The method according to claim 12, wherein, The mixture does not contain solvent.

14. The method according to claim 12, wherein, The polyether-based polymer compound includes polyalkylene glycol.

15. The method according to claim 14, wherein, The polyalkylene glycol includes at least one selected from polyethylene glycol, polypropylene glycol, and copolymers comprising polyethylene glycol and polypropylene glycol.

16. A secondary battery, comprising: positive electrode; negative electrode; and Electrolytes, Wherein, one or more of the positive or negative electrodes are the dry electrodes according to claim 1.

17. A dry electrode comprising: Electrode active materials; Adhesives; and The polyether-based polymer compound, in amounts ranging from 0.1% to 15% by weight, is included based on 100% by weight of the total dry electrode content. in, The polyether-based polymer compound is a copolymer containing polyethylene glycol (PEG) and polypropylene glycol (PPG), wherein the mass ratio of PEG to PPG in the copolymer is 1.9:1 to 9:

1.

18. The dry electrode according to claim 17, wherein, The copolymer of PEG and PPG is a block copolymer with PEG and PPG as repeating segments, and Among them, the weight-average molecular weight of the polyether-based polymer compounds ranges from 100 g / mol to 70,000 g / mol.

19. The dry electrode according to claim 17, wherein, The dry electrode further comprises a carbon-based conductive material selected from natural graphite, artificial graphite, carbon black, carbon fiber, carbon nanotubes, graphene, graphene oxide, and activated carbon, wherein the conductive material is present in an amount of 0.1% to 10% by weight, based on 100% by weight of the total content of the dry electrode.

20. A secondary battery, comprising: positive electrode; negative electrode; and Electrolytes, Wherein, the negative electrode is the dry electrode according to claim 17, and When the negative electrode and lithium metal as the counter electrode are assembled into a half cell, and charged at 0.1C to a cutoff voltage of 10mV under constant current / constant voltage conditions, and then charged at a constant voltage of 10mV until the current drops to 0.05C, the half cell exhibits an initial coulombic efficiency of at least 81%.

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