Current collector for electrode

Abstract

The present application provides a current collector for an electrode. The present application provides a current collector for an electrode that exhibits low resistance under normal and storage conditions so as not to affect the performance and operation of a secondary battery, and can ensure stability by blocking the current flow of an electrode assembly through an increase in resistance under abnormal conditions caused by overcharging, exposure to high temperatures, explosion, and / or external impact. Furthermore, the present application provides a method for manufacturing the current collector for an electrode, an electrode and an electrode assembly including the current collector for an electrode, and a secondary battery including the above.

Description

Technology Field

[0001] The present application relates to a current collector for an electrode. Background Technology

[0002] The application areas of energy storage technology are expanding to include mobile phones, tablets, laptop PCs, and electric vehicles.

[0003] As the data processing speed of mobile devices such as mobile phones and tablets increases and usage time lengthens, the development of secondary batteries with high energy density and operating potential, long cycle life, and low self-discharge rate is underway.

[0004] Furthermore, as major developed countries curb the production of internal combustion engine-powered vehicles to address global warming and air pollution, leading automobile manufacturers are developing various electric vehicles; consequently, the importance of secondary batteries, which possess high energy density, high discharge voltage, and output stability, is steadily increasing as a power source.

[0005] However, in accordance with the above trend, the frequency of ignition or explosion accidents caused by overcharging, exposure to high temperatures, or external impact in devices or automobiles that use secondary batteries as an energy source is also increasing.

[0006] A major cause of such accidents is known to be a short circuit, in which the positive and negative electrodes inside the electrode assembly come into direct contact due to external stimuli. When a secondary battery is overcharged or exposed to high temperatures or external stimuli, the short circuit may occur due to shrinkage of the separator caused by a rise in the internal temperature of the secondary battery, or destruction of the internal structure of the secondary battery due to external impact.

[0007] When a short circuit occurs, the movement of lithium ions and electrons concentrates at the point where the positive and negative electrodes are in direct contact, which can accelerate internal heat generation. It is known that this leads to the generation of gases inside the battery, causing volume expansion and increasing the risk of ignition. The problem to be solved

[0008] This application relates to a current collector for an electrode.

[0009] The present application aims to provide a current collector for an electrode that exhibits low resistance under normal and storage conditions so as not to affect the performance and operation of the secondary battery, and can ensure stability by blocking the current flow of the electrode assembly through an increase in resistance under abnormal conditions caused by overcharging, exposure to high temperature, explosion and / or external shock.

[0010] In addition, another objective of the present application is to provide a method for manufacturing a current collector for the electrode, an electrode and an electrode assembly including the current collector for the electrode, and a secondary battery including the above. means of solving the problem

[0011] In this specification, the term "room temperature" means a natural temperature that has not been heated or cooled, and may mean, for example, any temperature within the range of 10°C to 30°C or a temperature of about 23°C or about 25°C or about 27°C.

[0012] In cases where the measured temperature affects the physical properties mentioned in this specification, unless specifically otherwise defined, said physical property is the physical property measured at room temperature.

[0013] The unit of temperature mentioned in this specification is Celsius (°C) unless specifically otherwise specified.

[0014] In this specification, the term atmospheric pressure refers to natural pressure that has not been pressurized or depressurized, and may typically refer to a pressure of about 730 mmHg to 790 mmHg.

[0015] In cases where the measured pressure affects the physical properties mentioned in this specification, unless specifically otherwise defined, said physical property is the property measured at the atmospheric pressure.

[0016] In this specification, the term "normal state of an electrode or secondary battery" means a normal operating state of a secondary battery, for example, a normal charging or discharging state of a secondary battery.

[0017] In this specification, the term "storage state of an electrode or secondary battery" means a state in which a secondary battery is stored in a state in which it is fully or partially charged or discharged.

[0018] In this specification, the term "abnormal state of an electrode or secondary battery" refers to a dangerous state, such as a state in which abnormal heat generation or explosion occurs in the secondary battery, etc.

[0019] This application relates to a current collector for an electrode.

[0020] The electrode current collector of the present application may include a current collector body and a polymer layer formed on the current collector body. The electrode current collector may be used to form an electrode. For example, an electrode formed using the electrode current collector may include an active material layer formed on the electrode current collector and the polymer layer of the current collector. FIG. 1 is a drawing showing an electrode having an active material layer (300) formed on the polymer layer (200) of an electrode current collector comprising the current collector body (100) and the polymer layer (200).

[0021] As shown in the drawing, in the electrode current collector or electrode, the current collector body (100) and the polymer layer (200), and the polymer layer (200) and the active material layer (300) may be in contact with each other, and other elements may exist between them. In addition, although the drawing shows a case where the active material layer (300) exists only on one side of the current collector body (100), the active material layer (300) may exist on both sides of the current collector body (100). In such a case, the polymer layer (200) may exist as two layers between each of the active material layer (300) existing on both sides of the current collector body (100) and the current collector body (100), or as one layer between either of the active material layer (300) existing on both sides and the current collector body (100).

[0022] The electrode formed as a current collector for the electrode of the present application may be an anode or a cathode applied to a secondary battery.

[0023] The polymer layer of the present application exhibits a so-called PTC (positive temperature coefficient) effect. Accordingly, the polymer layer can variably control the movement of charge through the electrode depending on the temperature.

[0024] By applying such a polymer layer, the electrode having the current collector of the present application can be applied to a secondary battery, etc., and exhibit low resistance under normal and storage conditions, and can ensure stability by increasing resistance under abnormal conditions caused by overcharging, exposure to high temperature, or external shock.

[0025] In order for a polymer layer to be applied to an electrode and exhibit the above-mentioned effect, the trend of the PTC effect exhibited by the polymer layer must be controlled. The PTC effect is a phenomenon in which resistance increases in proportion to temperature, and the temperature at which resistance rises due to the PTC effect, as well as the resistance of the polymer layer prior to this rise, affect the performance of the secondary battery. For example, if the PTC effect is excessively manifested at the temperatures under normal and storage conditions, the performance of the secondary battery cannot be properly achieved before stability is ensured.

[0026] The polymer layer disclosed in this specification has a PTC effect, and this PTC effect is controlled so that it does not affect the performance of the secondary battery under normal and storage conditions, and stability is ensured under abnormal conditions.

[0027] To manifest such a PTC effect, the crystallization characteristics of the conductive polymer within the polymer layer can be controlled. The conductivity of the polymer layer is influenced by the crystallinity of the conductive polymer; typically, conductivity increases as crystallinity increases, but if the crystallinity of the conductive polymer is compromised by exposure to high temperatures, conductivity decreases, which may lead to an increase in resistance. Therefore, for example, if the crystallinity of the conductive polymer is excessively high, the temperature at which the crystallinity breaks down and resistance rises also increases.

[0028] In the present application, a conductive polymer having a relatively long hydrocarbon chain is applied as described below, and a suitable PTC effect can be secured by controlling the crystallinity resulting from the alignment of the hydrocarbon chain by controlling the drying or annealing temperature during the polymer layer formation process.

[0029] In addition, the above hydrocarbon chain can control the interaction between the conductive polymer and the pore-forming agent described later, thereby allowing appropriate pores to be formed in the polymer layer. The pores formed in this way increase the reactivity of the polymer layer. For example, the pores increase the specific surface area of ​​the conductive polymer, and thereby increase the contact area with the electrolyte, so that the desired performance, for example, the PTC effect, can be secured more effectively.

[0030] As for the current collector body, one that is typically used as a current collector body for the positive or negative electrode can be used without any special restrictions.

[0031] As for the current collector body, there are no specific limitations on its type, size, or shape, as long as it is conductive without causing chemical changes in the application device, such as a secondary battery. Examples of materials that can be used as the current collector body include copper, aluminum, stainless steel, nickel, titanium, or calcined carbon, or materials surface-treated with carbon, nickel, titanium, or silver on the surface of copper, aluminum, or stainless steel may also be exemplified. The current collector body may be in the form of a film, sheet, foil, net, porous body, foam, or nonwoven fabric containing the above materials. In some cases, a known surface treatment may be performed on the surface of the current collector body to improve adhesion to other layers, such as a polymer layer or an active material layer.

[0032] The main body of such a current collector may typically have a thickness within the range of 3 μm to 500 μm, but is not limited thereto.

[0033] A polymer layer exists on one or both sides of the above-mentioned current collector body. The polymer layer may or may not come into contact with the above-mentioned current collector body. In this specification, the term polymer layer is a layer containing a polymer (e.g., a conductive polymer described below) in an amount greater than a certain amount. For example, the lower limit of the polymer content included in the polymer layer may be approximately 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, or 95 wt%, and the upper limit may be approximately 100 wt%, 95 wt%, 90 wt%, 85 wt%, 80 wt%, 75 wt%, 70 wt%, 65 wt%, 60 wt%, 55 wt%, or 50 wt%. The above content is the content of the polymer based on the total weight of the polymer layer. The above content may be a range below or less than any of the upper limits described above, or a range above or greater than any of the lower limits described above, or a range between any of the upper limits described above and above or greater than any of the lower limits described above.

[0034] In the present application, the conductivity of the conductive polymer or polymer layer can be controlled. In the present application, by controlling the conductivity, the electrode can operate effectively under normal and storage conditions.

[0035] For example, the lower limit of the conductivity of the polymer layer or conductive polymer may be approximately 100 μS / cm, 1000 μS / cm, 5000 μS / cm, 6000 μS / cm, 7000 μS / cm, 8000 μS / cm, 9000 μS / cm, 10000 μS / cm, 50000 μS / cm, 100000 μS / cm, 500000 μS / cm, 1.0 S / cm, 1.1 S / cm, 1.2 S / cm, 1.3 S / cm, 1.4 S / cm, 1.5 S / cm, 1.6 S / cm, 1.7 S / cm, 1.8 S / cm, 1.9 S / cm, 2.0 S / cm, 3.0 S / cm, 4.0 S / cm, or 5.0 S / cm. There are, and the upper limit may be 20 S / cm, 19 S / cm, 18 S / cm, 17 S / cm, 16 S / cm, 15 S / cm, 14.5 S / cm, 14 S / cm, 13.5 S / cm, 13 S / cm, 12.5 S / cm, 12 S / cm, 11.5 S / cm, 11 S / cm, 10.5 S / cm, 10 S / cm, 9.5 S / cm, 9 S / cm, 8.5 S / cm, 8 S / cm, 7.5 S / cm, 7 S / cm, 6.5 S / cm, 6 S / cm, 5.5 S / cm, 5 S / cm, or 4.5 S / cm. The conductivity described above may be within a range below or less than any of the upper limits described above, or above or greater than any of the lower limits described above, or between any of the upper limits described above and above or greater than any of the lower limits described above. By controlling the conductivity as described above, the polymer layer exhibits the required performance in both the ideal state and the normal state.

[0036] The above polymer layer may include a conductive polymer. As is known, a conductive polymer is a polymer that exhibits conductivity through a conjugated system of polymer chains and / or doping, etc.

[0037] By selecting the above-mentioned conductive polymer, an electrode current collector or electrode exhibiting the aforementioned characteristics can be effectively formed.

[0038] The polymer layer may comprise only the conductive polymer, or may additionally comprise the conductive polymer and other necessary additives. For example, the lower limit of the content of the conductive polymer included in the polymer layer may be approximately 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, or 95 wt%, and the upper limit may be approximately 100 wt%, 95 wt%, 90 wt%, 85 wt%, 80 wt%, 75 wt%, 70 wt%, 65 wt%, 60 wt%, 55 wt%, or 50 wt%. The above content is the content of the conductive polymer based on the total weight of the polymer layer. The above content may be a range below or less than any of the upper limits described above, or a range above or greater than any of the lower limits described above, or a range between any of the upper limits described above and above or greater than any of the lower limits described above.

[0039] The oxidation potential of the conductive polymer or polymer layer described above can be controlled according to the purpose. The method for measuring the oxidation potential is described in the examples of this specification. The oxidation potential varies depending on the electrode and electrolyte applied to the measurement; in this application, the oxidation potential is measured based on Li / Li+. In this application, a polymer layer or electrode with desired characteristics can be formed by controlling the oxidation potential measured by the measurement method described in the following examples.

[0040] The lower limit of the oxidation potential of the conductive polymer or polymer layer may be approximately 2V, 2.1V, 2.2V, 2.3V, 2.4V, 2.5V, 2.6V, 2.7V, 2.8V, 2.9V, 3V, 3.1V, 3.2V, 3.3V, 3.4V, 3.5V, 3.6V, 3.7V, 3.8V, 3.9V, or 4.0V, and the upper limit may be approximately 5V, 4.9V, 4.8V, 4.7V, 4.6V, 4.5V, 4.4V, 4.3V, 4.2V, or 4.1V. The oxidation potential may be within a range below or less than any of the upper limits described above, or within a range above or greater than any of the lower limits described above, or within a range between any of the upper limits described above and above or greater than any of the lower limits described above. By using a conductive polymer having such an oxidation potential, a polymer layer and an electrode with desired characteristics can be effectively formed.

[0041] The above conductive polymer may have a weight-average molecular weight within a predetermined range. The lower limit of the weight-average molecular weight of the above conductive polymer is 10,000 g / mol, 15,000 g / mol, 20,000 g / mol, 25,000 g / mol, 30,000 g / mol, 35,000 g / mol, 40,000 g / mol, 45,000 g / mol, 50,000 g / mol, 55,000 g / mol, 60,000 g / mol, 65,000 g / mol, 70,000 g / mol, 75,000 g / mol, 80,000 g / mol, 85,000 g / mol, 90,000 g / mol, 95,000 g / mol, 100,000 g / mol, 105,000 g / mol, 110,000 It may be approximately g / mol, 115,000 g / mol, 120,000 g / mol, 130,000 g / mol, 135,000 g / mol, or 140,000 g / mol, and the upper limit is 1,000,000 g / mol, 950,000 g / mol, 900,000 g / mol, 850,000 g / mol, 800,000 g / mol, 750,000 g / mol, 700,000 g / mol, 650,000 g / mol, 600,000 g / mol, 550,000 g / mol, 500,000 g / mol, 450,000 g / mol, 400,000 g / mol, 350,000 g / mol, It may be 300,000 g / mol, 250,000 g / mol, 200,000 g / mol, 195,000 g / mol, 190,000 g / mol, 185,000 g / mol, 180,000 g / mol, 175,000 g / mol, 170,000 g / mol, 165,000 g / mol, 160,000 g / mol, 155,000 g / mol, 150,000 g / mol, 145,000 g / mol, 140,000 g / mol, 135,000 g / mol, 130,000 g / mol, 125,000 g / mol, or about 120,000 g / mol.The weight-average molecular weight may be within a range below or less than any of the upper limits described above, or within a range above or greater than any of the lower limits described above, or between any of the upper limits described above and above or greater than any of the lower limits described above. By using a conductive polymer having such a weight-average molecular weight, a polymer layer and an electrode with desired characteristics can be effectively formed.

[0042] The molecular weight distribution of the conductive polymer, that is, the ratio of the weight-average molecular weight (Mw) to the horizontally equal molecular weight (Mn), may be within a predetermined range. The lower limit of the molecular weight distribution may be approximately 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, or 7, and the upper limit may be approximately 10, 9.5, 9, 8.5, 8, 7.5, 7, 6.5, or 6. The molecular weight distribution may be within a range below or less than any of the upper limits described above, or within a range above or greater than any of the lower limits described above, or within a range between any of the upper limits described above and above or greater than any of the lower limits described above. By using a conductive polymer having the above molecular weight distribution, a polymer layer with desired characteristics, an electrode current collector, and an electrode can be effectively formed.

[0043] The conductive polymer may be a thiophene-based polymer. In this application, a desired polymer layer can be efficiently formed by applying a thiophene-based polymer as the conductive polymer.

[0044] In this specification, the term "thiophene-based polymer" means a polymer comprising at least about 50 mol%, at least 55 mol%, at least 60 mol%, at least 65 mol%, at least 70 mol%, at least 75 mol%, at least 80 mol%, at least 85 mol%, or at least 90 mol% of polymerization units of thiophene-based monomers relative to the total polymerization units of the conductive polymer. The upper limit of the ratio of polymerization units of the thiophene-based monomers within the thiophene copolymer is not particularly limited and may, for example, be 100 mol% or less, 95 mol% or less, or 90 mol% or less.

[0045] The above thiophene series monomers are monomers containing a thiophene backbone.

[0046] In the present application, the conductive polymer may be a thiophene-based polymer containing hydrocarbon groups in its side chains.

[0047] The term hydrocarbon group refers to a monovalent residue derived from a hydrocarbon compound, examples of which include alkyl, alkenyl, or alkynyl groups. The monovalent hydrocarbon group may have a straight chain structure or a branched chain structure, and such hydrocarbon groups may be aligned during the manufacturing process to impart appropriate crystallinity to the polymer layer or conductive polymer, and may effectively form pores in relation to the pore-forming agent described below.

[0048] In order for the hydrocarbon group to perform the above-mentioned function, the number of carbon atoms of the monovalent hydrocarbon group may be controlled. For example, the lower limit of the number of carbon atoms of the monovalent hydrocarbon group may be approximately 3, 4, 5, 6, 7, or 8, and the upper limit may be approximately 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, or 9. The number of carbon atoms may be within a range below or less than any of the upper limits described above, or within a range above or greater than any of the lower limits described above, or within a range between any of the upper limits described above and above or greater than any of the lower limits described above.

[0049] In one example, the monovalent hydrocarbon group may have a straight chain or a branched chain structure. In the case where the monovalent hydrocarbon group has a branched chain structure, the number of carbon atoms described above may be the number of carbon atoms forming the longest straight chain structure even in the branched chain structure.

[0050] The monovalent hydrocarbon group mentioned above, along with the crystallinity described above, may also impart appropriate mobility during the polymerization process of the conductive polymer. A monomer containing such a monovalent hydrocarbon group imparts appropriate mobility to the monomer mixture and also diffuses within the monomer mixture to enable polymerization to occur with excellent efficiency. Furthermore, the conductive polymer having a monovalent hydrocarbon group can enable a polymer layer to be formed stably and uniformly on the main body of the current collector through appropriate mobility.

[0051] In one example, the conductive polymer may include a polymerization unit of the following chemical formula 1 as a thiophene-based monomer.

[0052] [Chemical Formula 1]

[0053]

[0054] In Chemical Formula 1, R1 and R2 are each independently hydrogen or a monovalent hydrocarbon group, or are connected to each other to form a divalent functional group of Chemical Formula 2 below. The monovalent hydrocarbon group is a hydrocarbon group included in the side chain of the aforementioned thiophene-based polymer, and details regarding this are as described above.

[0055] In Chemical Formula 1, at least one of R1 and R2 is the monovalent hydrocarbon group, or R1 and R2 are connected to each other to form the divalent functional group of Chemical Formula 2 below.

[0056] [Chemical Formula 2]

[0057]

[0058] In Chemical Formula 2, L1 and L2 are each independently a single bond, an alkylene group, or an alkylidene group, and R3 and R4 are each independently hydrogen or a monovalent hydrocarbon group. The monovalent hydrocarbon group is a hydrocarbon group included in the side chain of the aforementioned thiophene-based polymer, and details regarding this are as described above.

[0059] In Chemical Formula 2, at least one of R3 and R4 is the monovalent hydrocarbon group.

[0060] In Chemical Formula 2, the alkylene group refers to a divalent functional group formed by the removal of hydrogen atoms from two different carbon atoms in an alkane, and the term alkylidene group refers to a divalent functional group formed by the removal of two hydrogen atoms from one carbon atom in an alkane.

[0061] Unless otherwise specifically defined, the above alkylene group may be an alkylene group having 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms, and the above alkylidene group may be an alkylidene group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, unless otherwise specifically defined.

[0062] The above alkylene group and alkylidene group may each be straight-chain, branched-chain, or cyclic, and may optionally be substituted with one or more substituents.

[0063] In Chemical Formula 2, a single bond means that no atom exists at that site. That is, for example, if L1 in Chemical Formula 2 is a single bond, it means that the oxygen atom on the left side of L1 and the carbon atom on the right side are directly connected.

[0064] In Chemical Formula 2, a single bond is one where no atom exists at that site.

[0065] A detailed explanation of the above hydrocarbon group is as described above.

[0066] The above monovalent hydrocarbon group may be a straight-chain or branched-chain alkyl group, a straight-chain or branched-chain alkenyl group, or a straight-chain or branched-chain alkynyl group, depending on the above description. Accordingly, the lower limit of the number of carbon atoms of the alkyl group, alkenyl group, or alkynyl group may be approximately 3, 4, 5, 6, 7, or 8, and the upper limit may be approximately 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, or 9. The number of carbon atoms of the alkyl group, alkenyl group, or alkynyl group may be within a range below or less than any of the upper limits described above, or within a range above or greater than any of the lower limits described above, or between any of the upper limits described above and above or greater than any of the lower limits described above.

[0067] The above monovalent hydrocarbon group, alkyl group, alkenyl group, or alkynyl group may optionally be substituted with one or more substituents.

[0068] These monovalent hydrocarbon groups can form a polymer layer exhibiting an appropriate PTC effect as described above, and can also form appropriate pores in the polymer layer through interaction with a pore-forming agent.

[0069] The conductive polymer may additionally include the polymerization unit of the following chemical formula 3 along with the polymerization unit of chemical formula 1.

[0070] [Chemical Formula 3]

[0071]

[0072] In Chemical Formula 3, R5 and R6 are each independently hydrogen or polar functional groups, or are connected to each other to form the divalent functional group of Chemical Formula 4 below.

[0073] In Chemical Formula 3, at least one of R5 and R6 is a polar functional group, or R5 and R6 are connected to each other to form a divalent functional group of Chemical Formula 4 below.

[0074] [Chemical Formula 4]

[0075]

[0076] In Chemical Formula 4, L3 and L4 are each independently a single bond, an alkylene group, or an alkylidene group, and R7 and R8 are each independently hydrogen or the polar functional group.

[0077] In Chemical Formula 4, at least one of R7 and R8 is the polar functional group.

[0078] The specific details regarding each of the alkylene group and alkylidene group in Chemical Formula 4 and the specific details regarding the single bond are as in Chemical Formula 2.

[0079] In this specification, the term polar functional group is a functional group comprising one or more polar atoms, for example, oxygen and / or nitrogen. Examples of such polar functional groups include, but are not limited to, carboxyl groups, hydroxyl groups, amino groups, cyano groups, nitro groups, ether groups and / or functional groups of Formula 5 below.

[0080] [Chemical Formula 5]

[0081]

[0082] In Chemical Formula 5, L5 is a single bond, an alkylene group, or an alkylidene group, L6 is an alkylene group or an alkylidene group, R9 is hydrogen or an alkyl group, and n is a number in the range of 1 to 10.

[0083] The specific details regarding each of the alkylene group and alkylidene group in Chemical Formula 5 and the specific details regarding the single bond are as in Chemical Formula 2.

[0084] In Chemical Formula 5, the alkyl group may, in one example, be an alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, or may be a methyl group or an ethyl group. The alkyl group may be straight-chain, branched-chain, or cyclic, and suitably may be straight-chain or branched-chain.

[0085] In Chemical Formula 5, the lower limit of n may be approximately 1, 2, 3, or 4, and the upper limit may be approximately 10, 9, 8, 7, 6, 5, 4, or 3. The above n may be within a range below or less than any of the upper limits described above, or within a range above or greater than any of the lower limits described above, or within a range between any of the upper limits described above and above or greater than any of the lower limits described above.

[0086] By applying the above polar functional groups, a polymer layer containing a conductive polymer can be bonded to another layer with appropriate bonding strength, and by uniformly forming such a layer of conductive polymer, the desired protective function can be efficiently achieved.

[0087] Furthermore, the polar functional group can control the form of pores in the polymer layer through interaction with the pore-forming agent described later. That is, the hydrocarbon group included in the thiophene-based polymer is hydrophobic relative to the polar functional group, and the polar functional group is relatively hydrophilic. Since the pore-forming agent described later is typically hydrophilic, the ratio of polar functional groups within the polymer is linked to the interaction with the pore-forming agent, and accordingly, the form of pores can be controlled. Typically, the amount of the polar functional group and the size of the pores formed may be proportional.

[0088] In one example, the conductive polymer may be a copolymer comprising a polymerization unit of a monomer having a hydrocarbon group (hereinafter referred to as the first unit) and a polymerization unit of a monomer having a polar functional group (hereinafter referred to as the second unit).

[0089] In such cases, the weight portion of the functional groups (polar functional groups and hydrocarbon groups) within the conductive polymer can be controlled to ensure an appropriate effect.

[0090] In one example, the lower limit of the number of moles of the second unit per 100 moles of the first unit in the conductive polymer may be 0 moles, 1 mole, 2 moles, 3 moles, 4 moles, 5 moles, 6 moles, 7 moles, 8 moles, 9 moles, 9.5 moles, 10 moles, 15 moles, 20 moles, 25 moles, 30 moles, 35 moles, or 40 moles, and the upper limit may be 45 moles, 40 moles, 35 moles, 30 moles, 25 moles, 20 moles, 15 moles, or 10 moles. The number of moles of the second unit per 100 moles of the first unit described above may be within a range below or less than any upper limit among the upper limits described above, or within a range above or greater than any lower limit among the lower limits described above, or within a range between any upper limit below or less than any upper limit described above and any lower limit among the lower limits described above. A polymer layer with desired characteristics can be efficiently formed within such a range.

[0091] In one example, the first unit may be a polymerization unit of Formula 1, and the second unit may be a polymerization unit of Formula 3.

[0092] The polymer layer may include additional components along with the conductive polymer. Additionally, the polymer layer may be in a state where pores are formed while containing the conductive polymer.

[0093] In one example, the polymer layer may include a pore-forming agent together with the conductive polymer, or the polymer layer may have pores formed on the surface and / or inside while including the conductive polymer. In another example, the polymer layer may have pores formed on the surface and / or inside while including a pore-forming agent together with the conductive polymer.

[0094] The pores formed by the above pore-forming agent increase the specific surface area of ​​the polymer layer and, accordingly, expand the active area interacting with the electrolyte, thereby maximizing the efficiency of oxidation / reduction of the conductive polymer and forming a heat conduction path, so that a rapid and efficient PTC effect can be exerted when needed.

[0095] The above pore-forming agent is a substance that causes pores to be formed in the polymer layer. If a substance having appropriate polarity and / or solubility is selected in relation to the polarity and / or solubility of the conductive polymer or the polarity of the solvent used in the process of forming the polymer layer, a state similar to that in which so-called micelles are formed is achieved during the process of forming the polymer layer, thereby allowing the pores to be formed.

[0096] Such pore-forming agents may remain in the polymer layer where pores are formed, or they may be removed. To remove the pore-forming agents, for example, a method may be used to dissolve and remove the pore-forming agents by applying an etching process using a suitable solvent.

[0097] When a pore-forming agent remains in a polymer layer in which pores are formed, the pore-forming agent may exist between the pores and the conductive polymer of the polymer layer. That is, a state similar to that in which the aforementioned micelles are formed by the pore-forming agent is achieved, and since pores are created thereby, the pore-forming agent within the polymer layer may exist between the pores and the conductive polymer, for example, at the interface between the pores and the conductive polymer.

[0098] As such a pore-forming agent, a suitable material may be selected and used depending on the type of conductive polymer and / or the type of solvent.

[0099] Examples of pore-forming agents that may be used include, but are not limited to, one or more selected from the group consisting of metal salts, carbonate compounds, nitrile compounds, sulfate compounds, sulfone compounds, and sulfite compounds.

[0100] In the above, the metal salt may be, for example, a lithium salt or a sodium salt; specifically, the metal salt may be LiTFSI, LiPF6, LiDFOB, LiBF4, NaCl, lithium difluorodioxalatophosphate, lithium tetrafluorooxalatophosphate, lithium difluorooxalatoborate, or lithium difluorophosphate, etc.; the carbonate compound may be vinylene carbonate, vinylethylene carbonate, or fluoroethylene carbonate, etc.; the nitrile compound may be succinonitrile or adiponitrile, etc.; and the sulfone compound may be propene sulfone or propane sulfone. Sultones, etc. may be used, and as sulfate or sulfite compounds, ethylene sulfate, dicycloglyoxalsulfate, or ethylene sulfite may be used, but are not limited thereto.

[0101] When the polymer layer includes a pore-forming agent along with a conductive polymer, the content can be appropriately controlled considering the desired pore formation pattern. For example, the lower limit of the weight ratio of the pore-forming agent relative to 100 parts by weight of the conductive polymer in the polymer layer may be approximately 0.5 parts by weight, 1 part by weight, 5 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, or 50 parts by weight, and the upper limit may be approximately 300 parts by weight, 250 parts by weight, 200 parts by weight, 150 parts by weight, 100 parts by weight, 95 parts by weight, 90 parts by weight, 85 parts by weight, 80 parts by weight, 75 parts by weight, 70 parts by weight, 65 parts by weight, 60 parts by weight, 55 parts by weight, 50 parts by weight, 45 parts by weight, 40 parts by weight, 35 parts by weight, or 30 parts by weight. The above weight ratio may be within a range below or less than any of the upper limits described above, or within a range above or greater than any of the lower limits described above, or within a range between any of the upper limits described above and above or greater than any of the lower limits described above. The above ratio may be adjusted considering the desired pore formation form.

[0102] The pores of the polymer layer formed by the above-mentioned pore-forming agent, etc., may exist on the surface and / or inside the polymer layer. Whether pores exist and the size of the pores can be confirmed using a Scanning Electron Microscope (SEM).

[0103] The size of the pores formed above can be controlled through the amount of the pore-forming agent used or process conditions. For example, when pores are formed on the surface of the polymer layer, the lower limit of the size of the pores formed on the surface may be approximately 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, or 300 nm, and the upper limit may be approximately 50 μm, 45 μm, 40 μm, 35 μm, 30 μm, 25 μm, 20 μm, 15 μm, 10 μm, or 5 μm. The size of the pores may be within a range below or less than any of the upper limits described above, or within a range above or greater than any of the lower limits described above, or within a range between any of the upper limits described above and above or greater than any of the lower limits described above.

[0104] The polymer layer described above may include additional necessary components in addition to the aforementioned conductive polymer and / or pore-forming agent.

[0105] The above polymer layer can exhibit a PTC effect as described above.

[0106] For example, the polymer layer above may have △ρ of Formula 1 below within a predetermined range.

[0107] [Equation 1]

[0108] △ρ = ρ MAX / ρ RT Max{(Rn+5 / Rn) / 5}

[0109] ρ in Equation 1 RT is the DC resistance of the current collector for the electrode measured at 25℃, and ρ MAX is the DC resistance of the current collector for the electrode measured at 140℃.

[0110] The above △ρ can be verified according to the PTC (Positive Temperature Coefficient) effect measurement method in the embodiment item of this specification.

[0111] The lower limit of the above △ρ may be approximately 3, 5, 7, 9, 10, 11, 12, 13, 14, or 14.5, and the upper limit may be approximately 50, 45, 40, 35, 30, 25, 20, or 15. The above △ρ may be within a range greater than or equal to any of the lower limits described above, or within a range between any of the upper limits described above, which is less than or equal to any of the upper limits described above, and greater than or equal to any of the lower limits described above.

[0112] The thickness of the polymer layer can be appropriately controlled according to the purpose. For example, the lower limit of the thickness may be approximately 10 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, or 500 nm, and the upper limit may be approximately 2 μm, 1.5 μm, 1 μm, 950 nm, 900 nm, 850 nm, 800 nm, 750 nm, 700 nm, 650 nm, 600 nm, 550 nm, 500 nm, 450 nm, 400 nm, 350 nm, or 300 nm. The above thickness may be within a range below or less than any of the upper limits described above, or within a range above or greater than any of the lower limits described above, or within a range between any of the upper limits described above and above or greater than any of the lower limits described above. The above ratio may be adjusted considering the desired pore formation shape.

[0113] The present application also relates to a method for manufacturing the current collector for the electrode. The manufacturing method includes a process for controlling the crystallinity of the conductive polymer and a process for forming the pores.

[0114] The above manufacturing method may include a first step of preparing a coating solution comprising the conductive polymer and the pore-forming agent, and a second step of forming a polymer layer on the current collector body using the coating solution.

[0115] In the first step above, a step of mixing the conductive polymer present in the first solvent and the pore-forming agent present in the second solvent is performed.

[0116] In this process, the dipole moment of each of the first and second solvents can be controlled. In one example, the first solvent may be a so-called non-polar solvent, and the second solvent may be a so-called polar solvent. Furthermore, solvents that have miscibility with each other are selected as the first and second solvents. Additionally, as the pore-forming agent, a material that has solubility above a certain level with respect to the polar solvent and solubility that is relatively lower with respect to the non-polar solvent compared to the polar solvent may be selected. Furthermore, regarding the two types of solvents, the polymer may be selected such that it has a certain degree of solubility with respect to the two types of solvents. In a state where such materials are mixed, the pore-forming agent is dissolved above a certain amount in the polar solvent, and the two types of solvents are mixed due to their miscibility with each other; it is presumed that in this state, a so-called micelle is formed or a similar state is formed, thereby forming the desired porous polymer layer.

[0117] For example, the first solvent is a non-polar solvent, and the upper limit of its dipole moment (at 20°C) may be approximately 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, or 0.35, and the lower limit may be approximately 0, 0.1, 0.15, 0.2, 0.25, or 0.3. The dipole moment of the first solvent may be within a range below or less than any of the upper limits described above, or within a range between any of the upper limits described above and above or greater than any of the lower limits described above. Examples of such a first solvent include toluene, but other types of solvents may also be used as long as they have the above dipole moment.

[0118] For example, the second solvent is a polar solvent, and the upper limit of its dipole moment (at 20°C) may be approximately 4, 3.5, 3, 2.5, 2, or 1.8, and the lower limit may be approximately 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, or 1.7. The dipole moment of the second solvent may be within a range greater than or exceeding any of the lower limits described above, or within a range between any of the upper limits described above and above or exceeding any of the lower limits described above. Examples of such a second solvent include THF (tetrahydrofuran), but other types of solvents may also be used as long as they have the above dipole moment.

[0119] The lower limit of the ratio (D2 / D1) of the dipole moment (at 20°C) of the second solvent (D2) to the dipole moment (D1) of the first solvent (at 20°C) may be approximately 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, or 5.5, and the upper limit may be approximately 20, 18, 16, 14, 12, 10, 9, 8, 7, or 6. The ratio D2 / D1 may be within a range greater than or equal to any of the lower limits described above, or within a range less than or equal to any of the upper limits described above, or within a range between any of the upper limits described above and greater than or equal to any of the lower limits described above. Suitable pores can be formed within this range.

[0120] The first and second solvents described above may be selected to have different polarities but be miscible with each other. Whether the solvents are miscible with each other can be determined by known methods. For example, the miscibility can be determined using the solvent miscibility chart provided by Merck (https: / / www.sigmaaldrich.com / KR / ko / technical-documents / technical-article / analytical-chemistry / purification / solvent-miscibility-table). Solvents classified as miscible in the said chart are also deemed to be miscible in this specification.

[0121] In the first step, the lower limit of the concentration of the conductive polymer present in the first solvent may be approximately 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, or 3 wt%, and the upper limit may be approximately 20 wt%, 18 wt%, 16 wt%, 14 wt%, 12 wt%, 10 wt%, 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5 wt%, 4 wt%, or 3 wt%. The ratio may be within a range greater than or exceeding any of the lower limits described above, or within a range less than or below any of the upper limits described above, or within a range between any of the upper limits described above and greater than or above any of the lower limits described above. Suitable pores can be formed within this range. The concentration of the polymer may be, for example, the ratio of the weight of the polymer to the sum of the weight of the first solvent (W1) and the weight of the polymer present in the first solvent (W2) (100×W2 / (W1+W2)).

[0122] In the first step, the lower limit of the concentration of the pore-forming agent present in the second solvent may be approximately 30 wt%, 35 wt%, 40 wt%, 45 wt%, or 50 wt%, and the upper limit may be approximately 80 wt%, 75 wt%, 70 wt%, 65 wt%, 60 wt%, 55 wt%, or 50 wt%. The ratio may be within a range greater than or equal to any of the lower limits described above, or within a range less than or equal to any of the upper limits described above, or within a range between any of the upper limits described above and greater than or equal to any of the lower limits described above. Suitable pores can be formed within this range. The concentration of the pore-forming agent may be, for example, the ratio of the weight of the pore-forming agent to the sum of the weight of the second solvent (W3) and the weight of the pore-forming agent present in the second solvent (W4) (100×W4 / (W3+W4)).

[0123] The ratio of the conductive polymer and the pore-forming agent mixed in the first step above can be adjusted considering the purpose. For example, the lower limit of the weight ratio of the pore-forming agent mixed in the first step relative to 100 parts by weight of the conductive polymer may be approximately 0.5 parts by weight, 1 part by weight, 5 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, or 50 parts by weight, and the upper limit may be approximately 400 parts by weight, 350 parts by weight, 300 parts by weight, 250 parts by weight, 200 parts by weight, 150 parts by weight, 100 parts by weight, 95 parts by weight, 90 parts by weight, 85 parts by weight, 80 parts by weight, 75 parts by weight, 70 parts by weight, 65 parts by weight, 60 parts by weight, 55 parts by weight, 50 parts by weight, 45 parts by weight, 40 parts by weight, 35 parts by weight, or 30 parts by weight. The above weight ratio may be within a range below or less than any of the upper limits described above, or within a range above or greater than any of the lower limits described above, or within a range between any of the upper limits described above and above or greater than any of the lower limits described above. The above ratio may be adjusted considering the desired pore formation form.

[0124] The conductive polymer used in the first step above can be formed by a known polymerization method. For example, methods for manufacturing polythiophene include, typically, using an oxidative polymerization reaction or a radical reaction, and such methods can also be applied to the first step of forming the conductive polymer in the present application.

[0125] In the second step, a polymer layer is formed on the current collector body using the coating solution prepared in the first step. This process typically includes the steps of coating the coating solution onto the current collector body and drying and annealing the coated coating solution.

[0126] In this process, the crystallinity of the conductive polymer can also be controlled by the drying and annealing conditions mentioned above.

[0127] For example, the relationship between the temperature T of the drying and annealing and / or the time H and the time H of the annealing can be adjusted.

[0128] For example, the lower limit of the above temperature T may be approximately 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, or 125°C, and the upper limit may be approximately 200°C, 195°C, 190°C, 185°C, 180°C, 175°C, 170°C, 165°C, 160°C, 155°C, 150°C, 145°C, 140°C, 135°C, 130°C, 125°C, 120°C, 115°C, 110°C, 105°C, 100°C, 95°C, or 90°C. The above temperature may be within a range below or less than any of the upper limits described above, or within a range above or greater than any of the lower limits described above, or between any of the upper limits described above and above or greater than any of the lower limits described above. Within such a range, the alignment state of the catalyst chains of the conductive polymer is appropriately controlled, and accordingly, a conductive polymer or polymer layer of the desired crystallinity can be formed.

[0129] In the first aspect of the annealing process above, the lower limit of the product of the annealing temperature T and time H (T×H) may be approximately 10℃·hour, 15℃·hour, 20℃·hour, 25℃·hour, 30℃·hour, 35℃·hour, 40℃·hour, or 45℃·hour, and the upper limit may be approximately 100000℃·hour, 95000℃·hour, 90000℃·hour, 85000℃·hour, 80000℃·hour, 75000℃·hour, 70000℃·hour, 65000℃·hour, 60000℃·hour, 55000℃·hour, 50000℃·hour, 45000℃·hour, 40000℃·hour, 35000℃·hour, 30000℃·hour, 25000℃·hour, 20000℃·hour, 15000℃·hour, 10000℃·hour, 9500℃·hour, 9000℃·hour, 8500℃·hour, 8000℃·hour, 7500℃·hour, 7000℃·hour, 6500℃·hour, 6000℃·hour, 5500℃·hour, 5000℃·hour, 4500℃·hour, 4000℃·hour, 3500℃·hour, 3000℃·hour, 2500℃·hour, 2000℃·hour, 1500℃·hour, 1400℃·hour, 1300℃·hour, 1200℃·hour, 1100℃·hour, 1000℃·hour, 900℃·hour, 800℃·hour, 700℃·hour, 600℃·hour, 500℃·hour, 400℃·hour, 300℃·hour, 200℃·hour, 100℃·hour, 90℃·hour, 80℃·hour, 70℃·hour, 60℃·hour, 50℃·hour, It may be around 45℃·hour or 40℃·hour.The above product (T×H) may be within a range below or less than any of the upper limits described above, or within a range above or greater than any of the lower limits described above, or within a range between any of the upper limits described above and above or greater than any of the lower limits described above. Within such a range, the alignment state of the catalyst chains of the conductive polymer is appropriately controlled, and accordingly, a conductive polymer or polymer layer of the desired crystallinity can be formed.

[0130] The method of coating the above coating solution is not particularly limited, and known coating methods may be applied.

[0131] In the present application, a desired polymer layer and a current collector containing the same are manufactured through the above process. The above process may include an appropriate post-processing step if necessary. For example, a process of removing the pore-forming agent from the formed polymer layer using a solvent capable of dissolving the pore-forming agent may be additionally performed.

[0132] This application also relates to electrodes.

[0133] The above electrode may include a current collector for the electrode and an active material layer formed on the surface of the current collector for the electrode. Typically, the active material layer is formed by coating a slurry containing the electrode active material, binder, and conductive material onto a current collector (polymer layer), drying, and then rolling; this known method may be applied in the same way in the present application.

[0134] The above active material layer may use a layer that is typically applied.

[0135] Typically, the active material layer includes an electrode active material. There are no specific restrictions on the specific type of the electrode active material, and a material that forms a positive electrode or a negative electrode can be used.

[0136] For example, when the above active material layer is a positive electrode active material layer, the electrode active material is a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; a lithium iron oxide such as LiFe3O4; and a compound with the chemical formula Li 1+c1 Mn 2-c1 Lithium manganese oxides such as O4 (0≤c1≤0.33), LiMnO3, LiMn2O3, or LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, or Cu2V2O7; chemical formula LiNi 1-c2 M c2 Ni-site type lithium nickel oxide represented by O2 (wherein M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, satisfying 0.01≤c2≤0.3); chemical formula LiMn 2-c3 M c3 Lithium manganese composite oxides represented by O2 (where M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn and Ta, satisfying 0.01≤c3≤0.1) or Li2Mn3MO8 (where M is at least one selected from the group consisting of Fe, Co, Ni, Cu and Zn); may be lithium nickel cobalt manganese (NCM) composite oxides, lithium nickel cobalt manganese aluminum (NCMA) composite oxides, and LiMn2O4 in which some of the Li of the chemical formula is substituted with alkaline earth metal ions, but are not limited thereto.

[0137] When the above active material layer is a negative active material layer, the electrode active material may be a compound capable of reversible intercalation and deintercalation of lithium. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; metal oxides capable of doping and dedoping lithium, such as SiOa (0 < a < 2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites comprising the above metallic compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or more of these may be used.

[0138] As the above-mentioned cathode active material, a lithium thin film may be used, and as a carbon material, low-crystallinity carbon and high-crystallinity carbon may be used. Representative examples of low-crystallinity carbon include soft carbon and hard carbon, while representative examples of high-crystallinity carbon include amorphous, plate-like, flake-like, spherical, or fibrous natural graphite or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesocarbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch-derived cokes.

[0139] The electrode active material may be included in the active material layer in a range of about 80% to 99.5% by weight or 88% to 99% by weight relative to the total weight of the active material layer, but the above ratio may be changed depending on the use or design of the electrode.

[0140] The active material layer may additionally include a binder. The binder serves to improve adhesion between active materials and adhesion between the active material layer and the current collector body. Examples of the above binders are not particularly limited and include, for example, PVDF (Poly(vinylidene fluoride)), PVA (poly(vinyl alcohol)), SBR (styrene butadiene rubber), PEO (poly(ethylene oxide)), CMC (carboxyl methyl cellulose), cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, cyanoethylpullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, and polyvinylpyrrolidone. One or more of the following may be selected and used from the group consisting of polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate copolymer, and polyarylate.

[0141] In one example, the binder may be included in the active material layer in a range of 10 parts by weight or 0.5 to 5 parts by weight relative to 0.1 parts by weight relative to 100 parts by weight of the electrode active material, but is not limited thereto.

[0142] The active material layer may additionally include a conductive material as needed. As for the conductive material, any known material may be used without special restrictions as long as it is conductive without causing chemical changes in the secondary battery. For example, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, Farness black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; conductive tubes such as carbon nanotubes (CNT); metal powders such as fluorocarbon, aluminum, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide and / or conductive materials such as polyphenylene derivatives may be used.

[0143] The conductive material may be included in an amount of 0.1 to 20 parts by weight or 0.3 to 10 parts by weight relative to 100 parts by weight of the electrode active material in one example, but may be included in the active material layer, though it is not limited thereto.

[0144] The active material layer may optionally include additional known components in addition to the components described above.

[0145] The present application also relates to an electrode assembly or electrochemical device comprising the said electrode, e.g., a secondary battery.

[0146] The above-described electrochemical device may include the electrode as a positive electrode and / or a negative electrode. As long as the electrode of the present application is used as a negative electrode and / or a positive electrode, other configurations or manufacturing methods of the electrochemical device are not particularly limited, and known methods may be applied. Effects of the invention

[0147] The present application provides a current collector for an electrode. The present application provides a current collector for an electrode that exhibits low resistance under normal and storage conditions so as not to affect the performance and operation of a secondary battery, and can ensure stability by blocking the current flow of an electrode assembly through an increase in resistance under abnormal conditions caused by overcharging, exposure to high temperatures, explosion, and / or external impact. Furthermore, the present application provides a method for manufacturing the current collector for an electrode, an electrode and an electrode assembly including the current collector for an electrode, and a secondary battery including the above. Brief explanation of the drawing

[0148] FIG. 1 is a cross-sectional view of an exemplary electrode of the present application. Figure 2 is the result of NMR analysis of the monomer prepared in Preparation Example 1. Figures 3 to 9 are SEM images of the polymer layers of Examples 1 to 7, respectively. Figure 10 is an SEM image of the polymer layer of Comparative Example 2. Figure 11 is a diagram confirming the PTC effect of the polymer layer of the example and comparative example. Specific details for implementing the invention

[0149] The contents of the present application will be specifically explained through the following examples and comparative examples, but the scope of the present application is not limited by the following examples.

[0151] 1. NMR Analysis Method

[0152] 1 H-NMR analysis was performed at room temperature using an NMR spectrometer including a Bruker UltraShield spectrometer (300 MHz) equipped with a triple resonance 5 mm probe. The sample was diluted to a concentration of approximately 10 mg / ml in an NMR measurement solvent (CDCl3), and the chemical shift was expressed in ppm.

[0154] 2. GPC (Gel Permeation Chromatograph)

[0155] Molecular weight characteristics were measured using Gel Permeation Chromatography (GPC). The sample was placed in a 5 mL vial and diluted in chloroform to a concentration of approximately 1 mg / mL. Subsequently, the standard sample for calibration and the sample to be analyzed were filtered through a syringe filter (pore size: 0.45 μm) before measurement. Waters Empower 3 was used as the analysis program; the weight-average molecular weight (Mw) and number-average molecular weight (Mn) were determined by comparing the sample elution time with the calibration curve, and the molecular weight distribution (PDI) was calculated using the ratio (Mw / Mn). The GPC measurement conditions are as follows.

[0156] <GPC 측정 조건>

[0157] Device: Waters 2414

[0158] Column: 3 Waters Styragels used

[0159] Solvent: THF (Tetrahydrofuran)

[0160] Column temperature: 35℃

[0161] Sample concentration: 1 mg / mL, 1 μL injection

[0162] Standard Sample: Polystyrene (Mp: 3900000, 723000, 316500, 52200, 31400, 7200, 3940, 485)

[0164] 3. Thickness measurement

[0165] The thickness of the polymer layer, etc., was measured by taking Scanning Electron Microscope (SEM) (JEOL, JSM-7200F) images after cross-sectional processing using an ion milling machine (Hitachi, IM5000).

[0166] As described above, the conditions for forming a cross section by ion milling were carried out by setting the equipment to cross-section milling mode, the speed (reciprocation / min) to 3, the acceleration voltage to 6.0 kV, the discharge voltage to 15 kV, the current to 150 μA, and the time to 4 hours.

[0168] 4. Oxidation Potential Measurement Method

[0169] The oxidation potential was measured in the following manner. A polymer layer with a thickness of approximately 10 μm was formed on an aluminum foil (Al Foil) with a thickness of approximately 15 μm. The method of forming the polymer layer described above was applied identically to the method described in each example or comparative example, provided that the thickness of the polymer layer fell within the aforementioned range. Subsequently, a separator and a lithium film were laminated onto the polymer layer to produce a laminate comprising aluminum foil / polymer layer / separator / lithium film, which was then die-cut into a circular shape with a diameter of approximately 1.4 cm. A coin cell was manufactured using the die-cut circular laminate and an electrolyte (using the Welcos CR2032 Coin Cell Kit). As described above, the WL20C model from W-Scope Korea was used as the separator, a lithium film with a thickness of approximately 100 μm was used, and as the electrolyte, a 1M LiPF6 solution (solvent: EC / DMC / EMC=3 / 4 / 3 (mass ratio), EC: Ethylene Carbonate, DMC: dimethyl carbonate, EMC: ethylmethyl carbonate) from Enchem was used. For the coin cell, the oxidation potential was measured at 25°C using a potentiostat (manufacturer: Princeton Applied Research, product name: PARASTAT-MC). The oxidation potential was measured by cyclic voltammetry (CV) in the range of 1.5V to 5.5V at a scan rate of 0.17 mV / sec to 0.5 mV / sec.

[0171] 5. SEM (Scanning Electron Microscope) Analysis

[0172] Whether pores were formed in the polymer layer, as well as the size and density of the pores, were analyzed using SEM images. A Hitachi S4800 model was used to obtain the SEM images. To measure the oxidation potential, a specimen was prepared by forming a polymer layer (thickness: approximately 1 μm) on an Al foil with a thickness of approximately 15 μm in the same manner as described above. The specimen was cut to a width and length of approximately 1 cm, loaded into the SEM holder, and coated with Pt for 120 seconds under an argon atmosphere. Subsequently, the magnification was adjusted within the range of 500x to 20,000x, and SEM images were captured under a voltage condition of 5 kV. Cross-sectional imaging was performed in the same manner after cross-sectional processing using the ion milling method described above.

[0174] 6. Measurement of PTC (Positive Temperature Coefficient) Effect

[0175] The PTC effect was evaluated by fabricating a coin cell for measuring DC resistance, mounting the coin cell in a coin cell jig inside a Convection Oven (Manufacturer: Jiotec, Product Name: OF3-05W) and positioning it in the center, and observing the change in resistance according to temperature.

[0176] The above coin cell (standard capacity: 200 mAh / g) was manufactured using a CR2032 standard coin cell kit (Welcos CR2032 coin cell kit). The electrode prepared in the example or comparative example was used as the positive electrode, and a lithium film (thickness: 100 μm) was used as the negative electrode. As the electrolyte, a 1M LiPF6 solution (solvent: EC / DMC / EMC=3 / 4 / 3 (mass ratio), EC: Ethylene Carbonate, DMC: dimethyl carbonate, EMC: ethylmethyl carbonate) was used as the carbonate-based electrolyte, and a PE (poly(ethylene)) separator (WL20C model from W-Scope Korea) was used as the separator.

[0177] The above DC resistance was measured by applying a voltage of 4.3 eV to the coin cell for 10 minutes and using a Fluke digital multimeter (FLUKE-87-5).

[0178] The above coin cell was placed in the center of a Convection Oven (Manufacturer: Jiotec, Product Name: OF3-05W) by attaching it to a coin cell jig, and the oven temperature was set so that the initial temperature was 25℃, the final temperature was 140℃, and the temperature increased by 5℃ per minute. The above coin cell was connected to a resistance measuring multimeter (Fluke's digital multimeter (FLUKE-87-5)) located outside the oven to enable resistance measurement. Subsequently, DC resistance was measured at each temperature level (measured up to 140℃ while increasing the measurement temperature by 5℃ in the order of 25℃, 30℃, 35℃, and 40℃).

[0180] 7. Discharge Capacity Measurement

[0181] The discharge capacity was evaluated by fabricating a coin cell. A coin cell (reference capacity: 200 mAh / g) for verifying the discharge capacity was fabricated using a CR2032 standard coin cell kit (Welcos CR2032 coin cell kit). The electrode prepared in the example or comparative example was used as the positive electrode, and a lithium film (thickness: 100 μm) was used as the negative electrode. As the electrolyte, a 1M LiPF6 solution (solvent: EC / DMC / EMC=3 / 4 / 3 (mass ratio), EC: Ethylene Carbonate, DMC: dimethyl carbonate, EMC: ethylmethyl carbonate) was used as the carbonate-based electrolyte, and a PE (poly(ethylene)) separator (WL20C model from W-Scope Korea) was used as the separator.

[0182] For the above coin cell, 0.1C / 0.1C capacity and 0.5C capacity were measured.

[0183] The 0.1C / 0.1C capacity was measured by setting the charge termination voltage to 4.5V and the charge termination current to 1 mA, charging at a rate of 0.1C using the CC (Constant Current) / CV (Constant Voltage) method, setting the discharge termination voltage to 4.5V, and discharging at a rate of 0.1C using the CC (Constant Current) method, with the process being one cycle, and repeating the above cycle twice.

[0184] The 0.5C capacity was measured by setting the charge / discharge cutoff voltage to 4.5V and the charge cutoff current to 1 mA, charging at a rate of 0.5C using the CC (Constant Current) / CV (Constant Voltage) method, setting the discharge cutoff voltage to 4.5V, and discharging at a rate of 0.5C / 1.0C / 2.0C using the CC (Constant Current) method, and repeating the above cycle once.

[0185] Cell performance was evaluated under 0.1C capacity measurement conditions using the above method, and the high-temperature life performance of the cell was also evaluated under 0.5C / 1.0C conditions.

[0187] Preparation Example 1. Synthesis of monomer (A)

[0188] The monomer of the following chemical formula A was synthesized in the following manner.

[0189] [Chemical Formula A]

[0190]

[0191] 1.372 g (12.02 mmol, 1 eq) of 3-methoxythiophene and 3 g (16.83 mmol, 1.4 eq) of triethylene glycol monomethyl ether were dissolved in 100 ml of toluene with 230 mg of p-toluenesulfonic acid (p-TsOH) and mixed. The mixture was reacted under reflux at 120°C, and the methanol produced by transetherification was removed using a Type 4A molecular sieve packed with a Soxhlet extractor. After refluxing for 24 hours, the reaction mixture was quenched with water, extracted with ethyl acetate, washed with brine, and dried over magnesium sulfate (MgSO4). The solvent was removed using a rotary evaporator, and the residue was purified by column chromatography with a methylene chloride / hexane (2:1) elution to obtain the target compound (monomer (A)). The NMR analysis results for the target compound (monomer (A)) are shown in Fig. 2.

[0193] Preparation Example 2. Synthesis of conductive polymer (A)

[0194] Polythiophene (A) was prepared by adding 3-octylthiophene (3OT) to a solution in which 3.20 g (19.71 mmol, 3eq) of iron(III) chloride was dissolved in 150 ml of methylene chloride and polymerizing at 25°C for 24 hours. The polymerization solution was placed in an osmotic membrane with a molecular weight of cut-off (MWCO) of 5000, and then immersed in 200 ml of acetonitrile solvent to remove unreacted iron(III) chloride, monomers, and low molecular weight oligomers. The residue precipitated inside the osmotic membrane was washed with methanol and dried at 60°C for 12 hours to prepare polythiophene (A). Polythiophene (A) had a weight-average molecular weight (Mw) and a number-average molecular weight (Mn) of 140,000 g / mol and 20,000 g / mol, respectively, and an oxidation potential of about 3.9 V to 4.1 V.

[0196] Preparation Example 3. Synthesis of conductive polymer (B)

[0197] Polythiophene (B) was prepared by adding 3.0 g (15.31 mmol, 1.0 eq) of 3-octylthiophene and 0.377 g (1.53 mmol, 0.1 eq) of the monomer (A) of Preparation Example 1 to a solution in which 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride was dissolved in 150 ml of methylene chloride, and polymerizing at 25°C for 24 hours. The polymerization solution was placed in an osmotic membrane with a molecular weight of cut-off (MWCO) of 5000, and then immersed in 200 ml of acetonitrile solvent to remove unreacted iron chloride and monomer. The residue precipitated inside the osmotic membrane was washed with methanol and dried at 60°C for 12 hours to prepare polythiophene (B). Polythiophene (B) had a weight-average molecular weight (Mw) and a number-average molecular weight (Mn) of 120,000 g / mol and 18,000 g / mol, respectively, and an oxidation potential of about 4.0 V to 4.1 V.

[0199] Example 1.

[0200] Preparation of coating solution

[0201] 0.3 g of polythiophene (A) from Preparation Example 2 was dissolved in 9.7 g of toluene to prepare a polymer solution with a concentration of about 3 wt%. Separately, 0.1 g of lithium salt (LiTFSI, Lithium bis(trifluoromethanesulfonyl)imide) was dissolved in 0.1 g of THF (Tetrahydrofuran) and mixed overnight to prepare a lithium salt solution with a concentration of about 50 wt%. The toluene is a good solvent for polythiophene (A) and has a dipole moment of about 0.31 D (at 20°C), and the THF is a good solvent for the lithium salt and has a dipole moment of about 1.75 D (at 20°C). In addition, the above toluene and THF are solvents that are miscible with each other according to the solvent miscibility chart provided by Merck (https: / / www.sigmaaldrich.com / KR / ko / technical-documents / technical-article / analytical-chemistry / purification / solvent-miscibility-table). A coating solution was prepared by mixing the above polymer solution and the lithium salt solution. At this time, the above polythiophene (A) and the lithium salt were present in the coating solution at a weight ratio of approximately 100:10 (polythiophene:lithium salt).

[0203] Manufacturing of electrode current collectors and electrodes

[0204] A current collector for an electrode was manufactured by coating the above-prepared coating solution onto an Al foil with a thickness of about 15 μm using a bar coating method and maintaining it at 130°C for about 60 minutes to form a layer (polymer layer) with a thickness of about 300 nm to 350 nm. Subsequently, an active material layer was formed on the polymer layer. The above active material layer was formed by applying a slurry containing lithium cobalt oxide (LiCoO2), carbon-based conductive material (ECP (Ketjen Black) 0.5%, SFG (Trimrex graphite) 0.4%, DB (Denka Black) 0.4%), PVDF (polyvinylidene fluoride), and NMP (N-Methyl-2-pyrrolidone) in a weight ratio of 75:1:1:23 (LiCoO2:conductive material:PVDF:NMP) onto the polymer layer with a thickness of about 90 μm using a doctor blade, drying at room temperature, and then further drying under vacuum conditions at 120°C. Subsequently, an electrode was manufactured by rolling to achieve a porosity of about 25%.

[0206] Example 2.

[0207] An electrode current collector and an electrode were prepared in the same manner as in Example 1, except that when preparing the coating solution, the polythiophene (B) of Preparation Example 3 was used instead of the polythiophene (A) of Preparation Example 2, and the coating solution was prepared such that the polythiophene (B) and the lithium salt were present in a weight ratio of about 100:10 (polythiophene:lithium salt).

[0209] Example 3.

[0210] An electrode current collector and an electrode were prepared in the same manner as in Example 1, except that a coating solution was used in which polythiophene (A) and a lithium salt were present in a weight ratio of approximately 100:30 (polythiophene:lithium salt) when preparing the coating solution.

[0212] Example 4.

[0213] An electrode current collector and an electrode were prepared in the same manner as in Example 1, except that a coating solution was used in which polythiophene (A) and a lithium salt were present in a weight ratio of approximately 100:50 (polythiophene:lithium salt) when preparing the coating solution.

[0215] Example 5.

[0216] An electrode current collector and an electrode were prepared in the same manner as in Example 1, except that LiPF6 was used as the lithium salt and a coating solution was used in which polythiophene (A) and the lithium salt were present in a weight ratio of about 100:30 (polythiophene:lithium salt) during the preparation of the coating solution.

[0218] Example 6.

[0219] An electrode current collector and an electrode were prepared in the same manner as in Example 1, except that LiDFOB (Lithium difluoro(oxalato)borate) was used as the lithium salt, and a coating solution was used in which polythiophene (A) and the lithium salt were present in a weight ratio of about 100:30 (polythiophene:lithium salt) during the preparation of the coating solution.

[0221] Example 7.

[0222] An electrode current collector and an electrode were prepared in the same manner as in Example 1, except that LiBF4 was used as the lithium salt, and a coating solution was used in which polythiophene (A) and the lithium salt were present in a weight ratio of about 100:30 (polythiophene:lithium salt) during the preparation of the coating solution.

[0224] Comparative Example 1.

[0225] An electrode was manufactured by forming an active material layer directly on an Al foil in the same manner as in Example 1, without forming a polymer layer.

[0227] Comparative Example 2.

[0228] A current collector and an electrode were each prepared using a coating solution that did not mix a lithium salt solution with a polymer solution obtained by dissolving the polythiophene (A) of Preparation Example 2 in a solvent (toluene) at a concentration of about 3 wt%.

[0230] Test Example 1. Confirmation of pore formation

[0231] SEM images were taken of the surface, cross-section, and interior of the polymer layer prepared in the examples or comparative examples to confirm whether pores were formed.

[0232] The above SEM images are as shown in Figures 3 to 10.

[0233] From the drawings, it can be seen that in the case of the examples (Figs. 3 to 9), pores were formed on the surface and / or inside the polymer layer, whereas in the case of Comparative Example 2 (Fig. 10), no pores were formed. From the drawings, it can be seen that the size of the pores formed on the surface of the polymer layer is approximately 300 nm to 5 μm.

[0234] In addition, in the case of the example, it was confirmed that the applied Li salt (pore-forming agent) was distributed at the interface between the pores formed in the polymer layer and the polymer layer.

[0236] Test Example 2. Characteristic Evaluation

[0237] The characteristics of the electrodes prepared in the examples or comparative examples were summarized and listed in Tables 1 and 2 below. Table 2 is the result of the high-temperature life performance evaluation.

[0238] 0.1C / 0.1 / C capacity 0.5C charge discharge of electricity Efficiency (%) 0.1C 0.5C 1C 2C Example 1 199.6 185.5 92.9 185.1 175.9 171.9 164.9 Example 2 199.4 188.0 94.3 187.5 178.9 175.3 168.4 Example 3 199.5 187.3 93.9 186.3 177.3 171.0 166.2 Example 4 199.4 188.1 94.3 186.8 178.8 174.4 166.4 Example 5 199.2 187.0 93.9 185.9 177.2 173.3 167.7 Example 6 199.7 187.1 93.7 186.5 177.9 173.8 168.2 Example 7 199.2 186.8 93.8 185.2 176.8 173.0 165.8 Comparative Example 1 200.1 188.6 94.3 187.4 178.0 173.6 167.9 Comparative Example 2 197.4 176.6 89.5 174.3 165.1 150.6 132.3

[0240] 45℃@40 cycle (retention) 0.5C / 1C Example 1 83% Example 2 97% Example 3 93% Example 4 98% Example 5 95% Example 6 94% Example 7 91% Comparative Example 1 98% Comparative Example 2 72%

[0242] In Table 3, the PTC intensity is the room temperature (25℃) resistance (ρ) confirmed in the DC resistance measurement for measuring the above PTC (Positive Temperature Coefficient) effect. RT Maximum resistance (ρ) MAX It is the value divided by ). The above maximum resistance (ρMAX ) is a value measured at approximately 140℃. Figure 11 shows the results of evaluating the above PTC effect.

[0243] PTC intensity(ρMAX / ρRT) Maximum resistance measurement temperature (°C) Example 1 3.83 140 Example 2 5.07 140 Example 3 9.75 140 Example 4 14.56 140 Example 5 10.96 140 Example 6 9.82 140 Example 7 9.92 140 Comparative Example 1 0.89 140 Comparative Example 2 2.74 140

Claims

Claim 1 A current collector for an electrode comprising: a main body of a current collector; and a polymer layer formed to be in contact with the main body of the current collector, wherein the polymer layer comprises a conductive polymer and a pore-forming agent. Claim 2 A current collector for an electrode according to claim 1, wherein pores are formed in the polymer layer and a pore-forming agent is present between the pores and the conductive polymer. Claim 3 In claim 1, the pore-forming agent is one or more current collectors for electrodes selected from the group consisting of metal salts, carbonate compounds, nitrile compounds, sulfate compounds, sulfone compounds, and sulfite compounds. Claim 4 In claim 3, a current collector for an electrode in which the metal salt is a lithium salt. Claim 5 In claim 1, the polymer layer comprises 0.5 to 300 parts by weight of a pore-forming agent per 100 parts by weight of a conductive polymer, for an electrode current collector. Claim 6 A current collector body; and an electrode current collector formed to be in contact with the current collector body and comprising a polymer layer including a conductive polymer, wherein pores are formed in the polymer layer. Claim 7 In claim 6, a current collector for an electrode having pores formed on the surface of a polymer layer. Claim 8 In claim 7, a current collector for an electrode having a pore size formed on the surface of a polymer layer within the range of 50 nm to 50 μm. Claim 9 In claim 1 or 6, the conductive polymer is a current collector for an electrode comprising a polymerization unit of the following Chemical Formula 1: [Chemical Formula 1] In Chemical Formula 1, R1 and R2 are each independently hydrogen or a hydrocarbon group having 4 or more carbon atoms, wherein at least one of R1 and R2 is the hydrocarbon group having 4 or more carbon atoms, or R1 and R2 are connected to each other to form a divalent functional group of Chemical Formula 2 below: [Chemical Formula 2] In Chemical Formula 2, L1 and L2 are each independently a single bond, an alkylene group, or an alkylidene group, and R3 and R4 are each independently hydrogen or a hydrocarbon group having 4 or more carbon atoms, wherein at least one of R3 and R4 is a hydrocarbon group having 4 or more carbon atoms. Claim 10 In claim 9, the current collector for an electrode is a straight-chain or branched-chain alkyl group, alkenyl group, or alkynyl group. Claim 11 In claim 9, the conductive polymer is a current collector for an electrode further comprising a polymerization unit of the following chemical formula 3: [Chemical Formula 3] In Chemical Formula 3, R5 and R6 are each independently hydrogen or polar functional groups, wherein at least one of R5 and R6 is the polar functional group, or R5 and R6 are connected to each other to form a divalent functional group of Chemical Formula 4 below: [Chemical Formula 4] In Chemical Formula 4, L3 and L4 are each independently a single bond, an alkylene group, or an alkylidene group, and R7 and R8 are each independently hydrogen or the polar functional group, wherein at least one of R7 and R8 is the polar functional group. Claim 12 In claim 11, an electrode current collector wherein the polar functional group is a carboxyl group, a hydroxyl group, an amino group, a cyano group, a nitro group, an ether group, or a functional group of the following chemical formula 5: [Chemical Formula 5] In Chemical Formula 5, L5 is a single bond, an alkylene group, or an alkylidene group, L6 is an alkylene group or an alkylidene group, R9 is hydrogen or an alkyl group, and n is a number in the range of 1 to 10. Claim 13 In claim 11, the conductive polymer is a current collector for electrodes comprising 45 moles or less of a unit of Formula 3 per 100 moles of a unit of Formula 1. Claim 14 In claim 1 or 6, a current collector for an electrode in which △ρ of the following Equation 1 is 3 or more: [Equation 1] △ρ = ρ MAX / ρ RT ρ in Equation 1 RT is the DC resistance of the current collector for the electrode measured at 25℃, and ρ MAX is the DC resistance of the current collector for the electrode measured at 140℃. Claim 15 In claim 1 or 6, the polymer layer is a current collector for an electrode having a thickness within the range of 10 nm to 2 μm. Claim 16 An electrode comprising: a current collector for an electrode according to claim 1 or 6; and an active material layer formed on a polymer layer of the current collector for an electrode. Claim 17 An electrode assembly comprising the electrode of claim 16. Claim 18 A secondary battery comprising the electrode assembly of claim 17.

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