Current collector

Abstract

This application relates to a current collector and its applications. This application provides a current collector and its applications that, under normal conditions, exhibit excellent electrical characteristics including low resistance, without affecting the performance and operation of a secondary battery, and under abnormal conditions, can form electrodes that can interrupt the current flow to the electrode assembly through an increase in resistance, thereby ensuring stability.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0108436 filed on August 18, 2023, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of the present specification.

[0002] The present specification discloses a current collector and uses thereof. Background Art

[0003] Energy storage technology has been expanding its application range to mobile phones, tablets, laptop computers, electric vehicles and the like.

[0004] As the data processing speed of mobile devices such as mobile phones and tablets increases and their usage time becomes longer, development of secondary batteries having high energy density and operating potential, long cycle life and low self-discharge rate is progressing.

[0005] In major developed countries, along with restricting production of automobiles driven by internal combustion engines to eliminate global warming and air pollution, major automobile manufacturers are also promoting the development of various electric vehicles, and the importance of secondary batteries having high energy density, high discharge voltage and output stability as their driving sources is increasing more and more.

[0006] In accordance with the above trend, in devices and automobiles using secondary batteries as energy sources, the frequency of occurrence of fire or explosion accidents caused by overcharging, exposure to high temperatures, or external impact is also increasing.

[0007] As a main cause of such accidents, a short phenomenon in which the positive electrode and the negative electrode inside the electrode assembly directly contact due to external stimulation is mainly known. When a secondary battery is overcharged or exposed to high temperatures or external stimuli, the short phenomenon may occur due to shrinkage of a separator caused by an increase in the internal temperature of the secondary battery, destruction of the internal structure of the secondary battery caused by external impact, or the like.

[0008] When a short circuit occurs, the movement of lithium ions and electrons concentrates through the area where the positive and negative electrodes are in direct contact, which can accelerate internal heat generation. This is known to cause gases and other substances to be generated inside the battery, leading to volume expansion and increasing the risk of fire. [Overview of the project] [Problems that the invention aims to solve]

[0009] This application relates to a current collector, an electrode, and its applications. The objective of this application is to provide a current collector and an electrode that, under normal conditions, exhibit low resistance and excellent electrical characteristics, without affecting the performance and operation of a secondary battery, and that, under abnormal conditions, ensure stability through an increase in resistance. This application also aims to provide applications for the said current collector and electrode. [Means for solving the problem]

[0010] In this specification, the term "room temperature" means a natural temperature that is neither heated nor cooled, for example, any temperature within the range of 10°C to 30°C, or a temperature of approximately 23°C, 25°C, or 27°C.

[0011] In this specification, if the measurement temperature affects the physical properties mentioned, the physical properties are those measured at room temperature unless otherwise specified. The unit of temperature mentioned in this specification is Celsius (°C) unless otherwise specified.

[0012] In this specification, the term "atmospheric pressure" means the natural pressure that is not pressurized or depressurized, and can typically mean a pressure of approximately 730 mmHg to 790 mmHg. In this specification, if the measurement pressure affects the physical properties, then, unless otherwise specified, the physical properties are those measured at the aforementioned normal pressure.

[0013] In this specification, if the measured humidity affects the physical properties, then, unless otherwise specified, the physical properties are those measured at standard humidity conditions.

[0014] In this specification, standard humidity means any relative humidity within the range of 40% to 60%, for example, relative humidity of approximately 40%, 45%, 50%, 55%, or 60%.

[0015] In this specification, the term "normal state" means the normal operating state (e.g., the normal charging or discharging state of a secondary battery) and / or storage state of electrical / electronic equipment such as a secondary battery.

[0016] In this specification, the term "abnormal condition" means a state in which abnormal heat generation, ignition, and / or explosion occur in electrical / electronic equipment such as secondary batteries, or a state in which the risk of such abnormal heat generation, ignition, and / or explosion increases. For example, an abnormal condition may be a state in which abnormal heat generation, ignition, or explosion occurs in a secondary battery due to a short circuit or the like, or a dangerous state in which the possibility of such heat generation, ignition, or explosion increases.

[0017] This application relates to a current collector. The current collector may be a current collector for an electrode.

[0018] The electrode current collector of this application may include a current collector body and a polymer layer formed on the current collector body. The current collector can be used for electrode formation. For example, an electrode formed using the electrode current collector may include the electrode current collector and an active material layer formed on the polymer layer of the current collector. Figure 1 is an exemplary cross-sectional view of a current collector including a current collector body (100) and a polymer layer (200), and Figure 2 is an exemplary cross-sectional view showing an electrode in which an active material layer (300) is formed on the polymer layer (200) of the current collector.

[0019] In the current collector or electrode, the current collector body (100), the polymer layer (200), and the polymer layer (200) and the active material layer (300) may be in contact with each other as shown in the drawing. In some cases, other elements may be present between the current collector body (100) and the polymer layer (200), or between the polymer layer (200) and the active material layer (300). Although the drawing shows a case where the active material layer (300) is present on only one side of the current collector body (100), the active material layer (300) may be present on both sides of the current collector body (100). In such a case, there may be two layers of the polymer layer (200) between the current collector body (100) and each of the active material layers (300) present on both sides of the current collector body (100), or there may be one layer between either of the active material layers (300) present on both sides and the current collector body (100).

[0020] The electrode formed by the current collector for electrodes of this application may be a negative electrode (anode) or a positive electrode (cathode) applied to a secondary battery.

[0021] The polymer layer can be designed to exhibit a so-called PTC (positive temperature coefficient) effect. Such a polymer layer can exhibit changes in conductivity with changes in temperature and / or applied voltage. Therefore, the polymer layer can variably control the movement of charge through the electrode with respect to temperature.

[0022] By applying such a polymer layer, the electrode having a current collector according to this application can be applied to secondary batteries and the like, exhibiting excellent electrical characteristics including low resistance under normal conditions, and ensuring stability by increasing resistance under abnormal conditions.

[0023] In order for a polymer layer to be applied to an electrode and exhibit the aforementioned effect, the tendency of the PTC effect exhibited by the polymer layer must be controlled. The PTC effect is an effect in which resistance increases in proportion to temperature. In order for an electrode to which a polymer layer having the PTC effect is applied to operate stably and to ensure stability in abnormal conditions, it is necessary to adjust the oxidation potential of the polymer layer, the electrical characteristics before the resistance increases due to the PTC effect, and the point in time at which the resistance increases due to the PTC effect.

[0024] For example, if the oxidation potential of the polymer layer is high relative to the electrode's active material, a potential drop may occur during rapid charge-discharge cycles under normal conditions. Furthermore, if the resistance of the polymer layer is too high under normal conditions, charge transfer is restricted, negatively impacting the operation of the secondary battery. Additionally, if the temperature at which the PTC effect manifests is within the normal temperature range, the secondary battery may not be able to perform optimally.

[0025] The polymer layer disclosed herein has a PTC effect, the timing of the PTC effect's manifestation is controlled, and it maintains stable oxidation potential and electrical properties before the PTC effect manifests.

[0026] To achieve such a PTC effect, a specific conductive polymer can be introduced into the polymer layer. For example, the electrical properties of the polymer layer are influenced by the state of the conductive polymer. For instance, when the conductive polymer is doped, the polymer layer exhibits low resistance, and when it is de-doped, the polymer layer exhibits high resistance. In this application, the conductive polymer can be conditioned to react to temperature and / or voltage, and to exhibit a transition between doped and de-doped states at the desired time.

[0027] In this application, as described later, a conductive polymer having a relatively long hydrocarbon chain (long-chain hydrocarbon functional group) is applied, and by controlling the drying or annealing temperature during the polymer layer formation process, a suitable PTC effect (for example, inducing an increase in the resistance of the polymer layer at a desired temperature (the temperature of an abnormal battery state)) can be ensured.

[0028] Furthermore, by introducing a conductive substance into the polymer layer and uniformly dispersing it, the oxidation potential and electrical properties can be appropriately maintained.

[0029] For example, the current collector or the electrode containing it may exhibit low resistance at room temperature (approximately 25°C). For example, the AC impedance resistance at 25°C, as determined by the polymer layer, current collector, or electrode, may be below a certain level. This may enable stable operation or storage of the secondary battery under normal conditions. The upper limit of the AC impedance resistance may be around 40, 38, 36, 34, 32, 30, 28, 26, 24, 22, 20, 18, 16, 14, 12, 10, 9, 8.5, or 8, and the lower limit may be around 0, 2, 4, 6, 8, or 10. The unit of the AC impedance resistance is Ω. The AC impedance resistance may be within a range that is less than or equal to any one upper limit selected from the listed upper limits; or within a range that is less than or equal to any one upper limit selected from the listed upper limits, and greater than or equal to any one lower limit selected from the listed lower limits. The AC impedance resistance is substantially the resistance observed in the coin cell to which the polymer layer, current collector layer, or electrodes are applied, and the method for measuring it follows the method described in "5. Measurement of AC Impedance Resistance" of the Examples section of this specification.

[0030] The polymer layer, current collector, or electrode containing the same exhibits low resistance as described above at room temperature (approximately 25°C) and shows a rapid increase in resistance when necessary. For example, the polymer layer, current collector, or electrode may have a ΔR within a certain range according to the following formula 1. [Formula 1] △R = 100 × (R 130 -R 25 ) / R 25

[0031] In Equation 1, R 25 R is the AC impedance resistance at 25°C. 130 This is the AC impedance resistance at 130°C. The AC impedance resistance R 25 and R 130 This is the resistance observed in the coin cell to which the polymer layer, current collector layer, or electrode is applied, and the method for measuring it follows the method described in "5. AC Impedance Resistance Measurement" of the Examples section of this specification.

[0032] The lower limit of △R in Equation 1 may be around 200%, 500%, 700%, 800%, 900%, 950%, 1,000%, 1,100%, 1,150%, 1,200%, 1,500%, 1,700%, 1,800%, 1,900%, 2,000%, 2,100%, or 2,200%, and its upper limit may be around 10,000%, 7,000%, 5,000%, 4,000%, 3,000%, 2,500%, 2,400%, 2,300%, or 2,200%. The aforementioned △R may be within the range of being greater than or exceeding any one of the lower limits selected from the listed lower limits; or it may be less than or equal to any one of the upper limits selected from the listed upper limits, while being greater than or exceeding any one of the lower limits selected from the listed lower limits.

[0033] The aforementioned properties are demonstrated by the polymer layer described above.

[0034] Due to the PTC effect of such a polymer layer, ΔC of the polymer layer, current collector or electrode calculated by the following formula 2 can be within a certain range. [Formula 2] ΔC=100×(C 25 -C 130 ) / C 25

[0035] In Formula 2, C 25 is the discharge capacity at 25°C, and C 130 is the discharge capacity after storage at 130°C for 10 minutes. The discharge capacities C 25 and C 130 are substantially discharge capacities confirmed with a coin cell to which the polymer layer, current collector layer or electrode is applied, and the measurement method follows the content described in "7. Measurement of Normal Temperature and High Temperature Discharge Capacity" in the Examples section of the present specification.

[0036] The lower limit of ΔC may be approximately 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or 85%, and the upper limit thereof may be approximately 500%, 450%, 400%, 350%, 300%, 250%, 200%, 150%, 100%, 95%, 90%, 85% or 80%. ΔC may be within a range that is greater than or equal to any one lower limit selected from the above-listed lower limits; or within a range that is less than or equal to any one upper limit selected from the above-listed upper limits and at the same time greater than or equal to any one lower limit selected from the above-listed lower limits.

[0037] The above characteristics can be achieved by introducing a polymer layer described later.

[0038] There are no particular limitations on the current collector body, and those commonly used as current collector bodies for positive electrodes or negative electrodes can be used.

[0039] The type, size, and shape of the current collector body are not particularly limited, as long as it does not induce chemical changes in the application device such as a secondary battery and is conductive. Examples of materials that can be used as the current collector body include copper, aluminum, stainless steel, nickel, titanium, or calcined carbon, or materials in which the surface of copper, aluminum, or stainless steel has been surface-treated with carbon, nickel, titanium, or silver. The current collector body may also be in the form of a film, sheet, foil, net, porous body, foam, or nonwoven fabric containing the material. In some cases, the surface of the current collector body may be subjected to known surface treatments to improve adhesion to other layers such as a polymer layer or an active material layer.

[0040] Such a current collector body may typically have a thickness in the range of 3 μm to 500 μm, but is not limited thereto.

[0041] A polymer layer is present on one or both sides of the current collector body.

[0042] In this specification, the term "polymer layer" refers to a layer containing a polymer. For example, the lower limit of the polymer content in the polymer layer may be approximately 30% by weight, 35% by weight, 40% by weight, 45% by weight, 50% by weight, 55% by weight, 60% by weight, 65% by weight, 70% by weight, 75% by weight, 80% by weight, 85% by weight, 90% by weight, or 95% by weight, and the upper limit may be approximately 100% by weight, 95% by weight, 90% by weight, 85% by weight, 80% by weight, 75% by weight, 70% by weight, 65% by weight, 60% by weight, 55% by weight, or 50% by weight. The content is the polymer content based on the total weight of the polymer layer. The content may be within a range that is greater than or greater than any one lower limit selected from the listed lower limits; or it may be less than or equal to any one upper limit selected from the listed upper limits, while being greater than or greater than any one lower limit selected from the listed lower limits.

[0043] The polymer layer does not have to be a so-called electrode active material layer. Therefore, the content of the electrode active material can be controlled within the polymer layer. For example, the upper limit of the content of the electrode active material within the polymer layer may be around 10% by weight, 9% by weight, 8% by weight, 7% by weight, 6% by weight, 5% by weight, 4% by weight, 3% by weight, 2% by weight, 1% by weight, 0.5% by weight, 0.1% by weight, 0.05% by weight, 0.01% by weight, 0.005% by weight, or 0.001% by weight, and the lower limit may be 0% by weight. The content is the content of the polymer based on the total weight of the polymer layer. The content may be within a range that is less than or equal to any one upper limit selected from the listed upper limits; or within a range that is less than or equal to any one upper limit selected from the listed upper limits, and greater than or equal to any one lower limit selected from the listed lower limits. The specific types of the electrode active material will be described later.

[0044] The polymer contained in the polymer layer may be a conductive polymer. A conductive polymer is, as is well known, a polymer that exhibits conductivity through a conjugated system of polymer chains and / or doping. In one example, the conductive polymer may be a polymer whose conductivity changes through doping and dedoping. In one example, the conductive polymer may be a conductive copolymer. A conductive copolymer is a type of conductive polymer and is distinguished from a conductive polymer in the form of a homopolymer in that it is a conductive polymer containing two or more monomer units.

[0045] The PTC effect exhibited by certain conductive polymers, as described later, can be adjusted according to the purpose.

[0046] The oxidation potential of the conductive polymer or polymer layer can be adjusted according to the purpose. In this specification, the oxidation potential is defined as lithium and lithium ions (Li / Li + This is the oxidation potential measured using ) as a reference.

[0047] The lower limit of the oxidation potential may be around 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, or 3.7V, and the upper limit may be around 6V, 5.5V, 5V, 4.9V, 4.8V, 4.7V, 4.6V, 4.5V, 4.4V, 4.3V, 4.2V, 4.1V, 4.0V, 3.9V, 3.8V, 3.7V, 3.6V, or 3.5V. The oxidation potential may be within a range that is less than or equal to any one upper limit selected from the listed upper limits; greater than or equal to any one lower limit selected from the listed lower limits; or less than or equal to any one upper limit selected from the listed upper limits, while also being greater than or equal to any one lower limit selected from the listed lower limits. By adjusting the oxidation potential to such a range, the desired characteristics can be effectively ensured.

[0048] The conductive polymer may have a weight-average molecular weight within a predetermined range. The lower limit of the weight-average molecular weight of the conductive polymer may be approximately 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, or 60,000, and the upper limit may be approximately 200,000, 150,000, 100,000, 95,000, 90,000, 85,000, 80,000, 75,000, 70,000, 65,000, 60,000, 55,000, or 50,000. The unit of the weight-average molecular weight is g / mol. The weight-average molecular weight may be within a range where it is less than or equal to any one upper limit selected from the listed upper limits; or within a range where it is greater than or equal to any one lower limit selected from the listed lower limits; or within a range where it is less than or equal to any one upper limit selected from the listed upper limits, while also being greater than or equal to any one lower limit selected from the listed lower limits. By using a conductive polymer having such a weight-average molecular weight, polymer layers, current collectors, and electrodes with the desired properties can be effectively formed.

[0049] The molecular weight distribution of the conductive polymer, i.e., the ratio of the weight-average molecular weight Mw to the water-average molecular weight Mn, Mw / Mn, may be within a predetermined range. The lower limit of the molecular weight distribution may be around 2, 2.5, 3, 3.5, or 4, and the upper limit may be around 10, 9, 8, 7.5, 7, 6.5, 6, 5.5, 5, 4.5, 4, or 3.5. The molecular weight distribution may be within a range where it is less than or equal to any one upper limit selected from the listed upper limits; within a range where it is greater than or equal to any one lower limit selected from the listed lower limits; or within a range where it is less than or equal to any one upper limit selected from the listed upper limits, and greater than or equal to any one lower limit selected from the listed lower limits. By using a conductive polymer having such a molecular weight distribution, polymer layers, current collectors, and electrodes with the desired properties can be effectively formed.

[0050] When the conductive polymer has the molecular weight characteristics described above, the desired PTC effect can be efficiently controlled. As will be described later, the PTC effect by the conductive polymer can be expressed by adjusting the de-doping efficiency through vibration at temperatures in which the functional groups (such as long-chain hydrocarbon functional groups described later) containing the conductive polymer increase. The type of vibration of such functional groups changes depending on the number of carbon atoms in the functional group, as will be described later, and also changes depending on the size and size distribution of the polymer containing the functional group. The weight-average molecular weight and molecular weight distribution reflect the size and size distribution. The weight-average molecular weight and molecular weight distribution can be measured by the method described in "2. GPC (Gel Permeation Chromatograph)" in the Examples section of this specification.

[0051] The conductive polymer may be polythiophene.

[0052] In this specification, the term "polythiophene" means a polymer containing thiophene monomer units at a certain level or higher. The number of moles of thiophene monomer units relative to the total number of moles of all monomer units in the polythiophene (M) is defined as the number of moles of thiophene monomer units. T Ratio 100 × M T The lower limit of / M may be approximately 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, 85 mol%, or 90 mol%, and its upper limit may be approximately 100 mol%, 95 mol%, or 90 mol%. The range may be within a range that is greater than or greater than any one lower limit selected from the listed lower limits; or within a range that is less than or equal to any one upper limit selected from the listed upper limits, while being greater than or greater than any one lower limit selected from the listed lower limits.

[0053] In this specification, a monomer unit means a form in which a monomer is polymerized and contained within a polymer, and a thiophene monomer means a monomer of the thiophene series that contains a thiophene skeleton.

[0054] The conductive polymer may contain long-chain hydrocarbon functional groups or monomer units having the long-chain hydrocarbon functional groups (hereinafter referred to as unit A). The conductive polymer may also be polythiophene. In such cases, the monomer having the long-chain hydrocarbon functional group may be a thiophene monomer.

[0055] In this specification, the term "long-chain hydrocarbon functional group" means a monovalent hydrocarbon group having a certain number of carbon atoms or more, or a monovalent functional group containing a hydrocarbon structure having the aforementioned certain number of carbon atoms or more.

[0056] For example, the lower limit of the number of carbon atoms present in the long-chain hydrocarbon functional group (i.e., the number of carbon atoms in the monovalent hydrocarbon group or hydrocarbon structure) may be approximately 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, and the upper limit may be approximately 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, or 4. The number of carbon atoms may be within the range of being greater than or exceeding any one of the lower limits selected from the listed lower limits; or it may be less than or equal to any one of the upper limits selected from the listed upper limits, while being greater than or exceeding any one of the lower limits selected from the listed lower limits.

[0057] The aforementioned number of carbon atoms may also be the number of carbon atoms in the straight-chain hydrocarbon chain present in the long-chain hydrocarbon functional group. That is, the monovalent hydrocarbon group or hydrocarbon structure present in the long-chain hydrocarbon functional group can have a straight-chain structure or a branched-chain structure, and even in the case of a branched-chain structure, the number of carbon atoms constituting the longest straight chain in that branched-chain structure may be within the aforementioned range. For example, if the branched-chain structure is a 2-ethylhexyl group, the number of carbon atoms constituting the longest straight chain is 6.

[0058] Examples of the long-chain hydrocarbon functional group include one or more selected from the group consisting of alkyl groups, alkenyl groups, alkynyl groups, alkoxy groups, alkylcarbonyl groups, and alkylcarbonyl oxy groups. In appropriate examples, the long-chain hydrocarbon functional group may be an alkyl group and / or an alkoxy group.

[0059] The number of carbon atoms in the alkyl group, alkenyl group and alkynyl group and the alkyl group present in the alkoxy group, alkylcarbonyl group and alkylcarbonyloxy may be within the range of the number of carbon atoms present in the long-chain hydrocarbon functional group (i.e., the number of carbon atoms in the monovalent hydrocarbon group or hydrocarbon structure).

[0060] For example, the alkyl group, alkenyl group and alkynyl group and the alkyl group present in the alkoxy group, alkylcarbonyl group and alkylcarbonyloxy may be linear or branched, and if it is branched, the number of carbon atoms constituting the longest linear chain in the branched chain structure may be within the range described above.

[0061] The aforementioned long-chain hydrocarbon functional group, which is an alkyl group, alkenyl group, alkynyl group, alkoxy group, alkylcarbonyl group, or alkylcarbonyloxy, may be optionally substituted with one or more substituents.

[0062] Such long-chain hydrocarbon functional groups are functional groups that can impart appropriate fluidity (mobility) to the monomers or the conductive polymer itself during the polymerization process of the conductive polymer. Monomers containing such long-chain hydrocarbon functional groups impart appropriate fluidity to the monomer mixture and diffuse within the monomer mixture, enabling polymerization with excellent efficiency. Furthermore, conductive polymers having long-chain hydrocarbon functional groups can ensure that a polymer layer is formed stably and uniformly between the current collector and the active material layer through appropriate fluidity.

[0063] The long-chain hydrocarbon functional groups can be appropriately oriented during the drying or annealing process applied in the polymer layer formation process, allowing for the adjustment of the PTC effect suitable for the polymer. The long-chain hydrocarbon functional groups exhibit enhanced vibrational energy at increased temperatures, thereby adjusting the efficiency of dedoping of anions bound to the polymer. Such dedoping induces an increase in resistance. The dedoping efficiency can be controlled by the length and / or amount of the long-chain hydrocarbon functional groups. For example, at the same temperature, the vibrational energy of relatively long chains is greater than that of relatively short chains, thereby allowing the desired PTC effect to be set through the control of the type, length, and / or ratio of the long-chain hydrocarbon functional groups.

[0064] For example, in order to appropriately achieve the above effect, the number of moles M of monomer units (unit A) having the long-chain hydrocarbon functional group relative to the total number of monomer units M of the conductive polymer L Ratio 100 × M L The / M ratio can be adjusted. For example, the ratio 100 × M L The lower limit of / M may be approximately 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, 85 mol%, 90 mol%, or 95 mol%, and the upper limit may be approximately 99 mol%, 98 mol%, 96 mol%, 95 mol%, 94 mol%, 93 mol%, 92 mol%, 91 mol%, or 90 mol%. The ratio may be within the range of being greater than or exceeding any one of the lower limits selected from the listed lower limits; or it may be less than or equal to any one of the upper limits selected from the listed upper limits, while being greater than or exceeding any one of the lower limits selected from the listed lower limits. The ratio 100 × M L The closer the upper and lower limits of / M are to the ratios (approximately 90 mol%) presented in the examples of this specification, the more effectively the desired effect can be achieved.

[0065] The conductive polymer may include the long-chain hydrocarbon functional groups, which are first and second hydrocarbon functional groups having different numbers of carbon atoms.

[0066] The first hydrocarbon functional group is a functional group with a relatively large number of carbon atoms among the long-chain hydrocarbon functional groups. The lower limit of the number of carbon atoms of such a first hydrocarbon functional group may be around 10, 11, or 12, and the upper limit may be around 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, or 10. The number of carbon atoms of the first hydrocarbon functional group may be within a range of being greater than or exceeding any one of the lower limits selected from the listed lower limits; or within a range of being less than or equal to any one of the upper limits selected from the listed upper limits, while being greater than or exceeding any one of the lower limits selected from the listed lower limits. The closer the lower limit of the number of carbon atoms of the first hydrocarbon functional group is to the value (12) presented in the examples of this specification, the more effectively the desired effect can be achieved.

[0067] Such first hydrocarbon functional groups exhibit enhanced vibrational energy at increased temperatures, thereby allowing control of the dedoping efficiency of conductive polymers. The onset temperature of dedoping of conductive polymers can be controlled through the content of the first hydrocarbon functional groups or through combinations with second hydrocarbon functional groups described later.

[0068] The second hydrocarbon functional group is a functional group with a relatively small number of carbon atoms among the long-chain hydrocarbon functional groups. The lower limit of the number of carbon atoms of such a second hydrocarbon functional group may be around 3, 4, 5, 6, 7, or 8, and the upper limit may be around 9, 8, 7, or 6. The number of carbon atoms of the second hydrocarbon functional group may be within a range of less than or equal to any one upper limit selected from the listed upper limits; or within a range of less than or equal to any one upper limit selected from the listed upper limits, and greater than or equal to any one lower limit selected from the listed lower limits. The closer the lower and upper limits of the number of carbon atoms of the second hydrocarbon functional group are to the values ​​(6) presented in the examples of this specification, the more effectively the desired effect can be achieved.

[0069] Such a second hydrocarbon functional group attenuates the effect of vibrational energy exhibited by the first hydrocarbon functional group at a predetermined temperature. Therefore, the first hydrocarbon functional group has the effect of lowering the onset point of the PTC effect, while the second hydrocarbon functional group has the effect of attenuating the first hydrocarbon functional group as described above.

[0070] The number of carbon atoms in each of the first and second hydrocarbon functional groups may be the number of carbon atoms in the linear hydrocarbon chain present in the hydrocarbon functional group. For example, each of the first and second hydrocarbon functional groups may independently be one or more selected from the group consisting of alkyl groups, alkenyl groups, alkynyl groups, alkoxy groups, alkylcarbonyl groups, and alkylcarbonyloxy groups, and in appropriate examples, they may be alkyl groups and / or alkoxy groups, and the number of carbon atoms may be the number of carbon atoms in the alkyl groups present in the alkyl groups, alkenyl groups, and alkynyl groups, and the alkoxy groups, alkylcarbonyl groups, and alkylcarbonyloxy groups.

[0071] The alkyl group, alkenyl group, and alkynyl group, and the alkyl group present in the alkoxy group, alkylcarbonyl group, and alkylcarbonyloxy, may be linear or branched in structure. If linear, the total number of carbon atoms may be within the range described above. If branched, the number of carbon atoms constituting the longest linear chain in the branched structure may be within the range described above.

[0072] As mentioned above, the number of carbon atoms in a long-chain hydrocarbon functional group is related to the vibration characteristics due to the applied thermal energy, and different numbers of carbon atoms result in different vibration characteristics, which are also related to the PTC characteristics of the conductive polymer. In the conductive polymer of this application, the first hydrocarbon functional group mainly plays a role in regulating the temperature at which the PTC effect is exhibited, that is, the temperature at which the resistance increases, while the second hydrocarbon functional group can play a role in suppressing the increase in resistance at relatively low temperatures.

[0073] In the conductive polymer, the ratio of the total number of moles M1 of monomer units having the first hydrocarbon functional group and the total number of moles M2 of monomer units having the second hydrocarbon functional group, M1 + M2, to the total number of moles M of monomer units of the conductive polymer, M, is 100 × (M1 + M2) / M, which is equal to the ratio of the aforementioned unit A, 100 × M L It can be adjusted within the same range as / M.

[0074] The lower limit of the ratio M2 / M1, which is the number of moles M2 of monomer units having the second hydrocarbon functional group in the conductive polymer to the number of moles M1 of monomer units having the first hydrocarbon functional group, may be approximately 0.01, 0.05, 0.1, 0.5, 1, 1.5, or 2, and the upper limit may be approximately 100, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, or 0.7. The ratio may be less than or equal to any one upper limit selected from the listed upper limits, greater than or equal to any one lower limit selected from the listed lower limits, or less than or equal to any one upper limit selected from the listed upper limits, while being greater than or equal to any one lower limit selected from the listed lower limits. The closer the lower and upper limits of the ratio M2 / M1 are to the ratios (approximately 0.5) presented in the examples of this specification, the more effectively the desired effect can be achieved.

[0075] Under such ratios, the conductive polymer or the polymer layer exhibits an appropriate PTC (Positive Temperature Coefficient) effect, shows stable electrical properties at normal temperatures, adjusts the surface properties of the polymer layer, and ensures excellent adhesion to the electrode or current collector.

[0076] The conductive polymer may contain, along with the long-chain hydrocarbon functional group or unit A, a polar functional group or a monomer unit having the polar functional group (hereinafter referred to as unit B). The monomer having the polar functional group may be a thiophene monomer.

[0077] In this specification, the term "polar functional group" refers to a functional group containing one or more polar atoms, such as oxygen and / or nitrogen. Examples of such functional groups include, but are not limited to, carboxyl groups, hydroxyl groups, amino groups, cyano groups, nitro groups, ether groups, or the functional group of chemical formula 3 below. In one example, the functional group of chemical formula 3 below may be used as the polar functional group. [ka] In chemical formula 3, L4 is a single bond, an alkylene group, or an alkylidene group; L3 is an alkylene group or an alkylidene group; R5 is a hydrogen atom or an alkyl group; and n is any number. 。

[0078] In chemical formula 3, the fact that L4 is a single bond means that L4 does not exist, and the oxygen atom between L4 and L3 is directly linked to the monomer.

[0079] The alkyl group R5 in chemical formula 3 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 it may be a methyl group or an ethyl group. The alkyl group may be linear, branched, or cyclic, and may preferably be linear or branched. The alkyl group may be optionally substituted with one or more substituents.

[0080] In this specification, the term "alkylene group" refers to a divalent functional group formed in an alkane by the removal of hydrogen atoms from two different carbon atoms, and the term "alkylidene group" refers to a divalent functional group formed in an alkane by the removal of two hydrogen atoms from one carbon atom.

[0081] In chemical formula 3, the alkylene groups L3 and L4 may, in one example, be alkylene groups 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, or they may be ethylene or propylene groups. The alkylene groups may be linear, branched, or cyclic, and may preferably be linear or branched. The alkylene groups may be optionally substituted with one or more substituents.

[0082] In chemical formula 3, the alkylidene groups L3 and L4 may, in one example, be alkylidene groups 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 they may be methylidene, ethylidene, or propylidene groups. The alkylidene groups may be linear, branched, or cyclic, and may preferably be linear or branched. The alkylidene groups may be optionally substituted with one or more substituents.

[0083] In chemical formula 3, the lower limit of n may be 1, 2, 3, or 4, and its upper limit may be approximately 10, 9, 8, 7, 6, 5, 4, or 3. The n may be within a range where it is less than or equal to any one upper limit selected from the listed upper limits, and greater than or equal to any one lower limit selected from the listed lower limits.

[0084] By applying the aforementioned polar functional groups, the polymer layer can be bonded to other layers with appropriate bonding strength, thereby uniformly forming such conductive polymer layers and efficiently achieving the desired protective function. Furthermore, the polar functional groups can also play a role in suppressing the PTC effect that is exhibited at relatively low temperatures.

[0085] The number of moles of polar functional groups and long-chain hydrocarbon functional groups in the conductive polymer can be controlled to ensure the appropriate effect.

[0086] For example, the number of moles M of the long-chain hydrocarbon functional groups in a conductive polymer. Land the number of moles M of the polar functional group P Ratio M L / M P The lower limit may be around 1, 5, 7, 8, 9, 10, 15, 16, 17, 18, or 19, and the upper limit may be around 500, 450, 400, 350, 300, 250, 200, 150, 100, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, or 10. The ratio M L / M P The ratio M may be within a range that is less than or equal to any one upper limit selected from the listed upper limits; or within a range that is greater than or equal to any one lower limit selected from the listed lower limits; or within a range that is less than or equal to any one upper limit selected from the listed upper limits, and greater than or equal to any one lower limit selected from the listed lower limits. L / M P The closer the upper and lower limits are to the ratios (approximately 9) presented in the examples of this specification, the more effectively the desired effect can be achieved.

[0087] The number of moles M of the unit A in the conductive polymer A The number of moles M of the aforementioned unit B B Ratio M A / M B The ratio M L / M P It can be adjusted within the same range. At this time, the number of moles M L The number of moles is M A Therefore, the number of moles M P The number of moles is M B This is the result.

[0088] The total number of moles M of units A and B of the conductive polymer relative to the total number of moles M of all monomer units. A +M B The ratio is 100 × (M A +M BThe lower limit of ) / M may be approximately 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, 85 mol%, 90 mol%, or 95 mol%, and the upper limit may be approximately 100 mol%, 95 mol%, or 90 mol%. The ratio may be within the range of being greater than or exceeding any one of the lower limits selected from the listed lower limits; or it may be less than or equal to any one of the upper limits selected from the listed upper limits, while being greater than or exceeding any one of the lower limits selected from the listed lower limits.

[0089] The specific structure of the monomer contained in the conductive polymer is not particularly limited as long as it is a thiophene monomer having the aforementioned long-chain hydrocarbon functional group and / or polar functional group.

[0090] For example, the conductive polymer is the thiophene monomer unit and may contain the monomer unit of the following chemical formula 1. [ka]

[0091] In chemical formula 1, R1 and R2 are independently hydrogen, the polar functional group, or the long-chain hydrocarbon functional group, but one or more of R1 and R2 may be the polar functional group or the long-chain hydrocarbon functional group.

[0092] In other examples, R1 and R2 in chemical formula 1 can be linked together to form a divalent functional group of the following chemical formula 2. [ka]

[0093] Each oxygen atom in chemical formula 2 can bond to the carbon atom to which R1 is bonded and the carbon atom to which R2 is bonded in chemical formula 1.

[0094] In chemical formula 2, L1 and L2 are independently a single bond, an alkylene group, or an alkylidene group, and R3 and R4 are independently hydrogen, a polar functional group, or a long-chain hydrocarbon functional group, but one or more of R3 and R4 are polar functional groups or long-chain hydrocarbon functional groups.

[0095] In chemical formulas 1 and 2, the specific types of polar functional groups and long-chain hydrocarbon functional groups are as described above. As described above, both the first and second hydrocarbon functional groups can be applied as the long-chain hydrocarbon functional groups. In such cases, within the scope of chemical formula 1, monomer units having the first hydrocarbon functional group and second monomer units having the second hydrocarbon functional group can be used, and the ratio between them can also follow the description above.

[0096] In chemical formula 2, the meaning of L1 or L2 being a single bond is the same as in the case of L4 in chemical formula 3. The specific types of alkylene and alkylidene groups of L1 and L2 in chemical formula 2 are the same as the alkylene and alkylidene groups in chemical formula 3.

[0097] The lower limit of the molar ratio of the monomer unit of chemical formula 1 to the total number of moles of all monomer units contained in the conductive polymer may be approximately 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, 85 mol%, or 90 mol%, and the upper limit may be approximately 100 mol%, 95 mol%, or 90 mol%. The range may be within a range that is greater than or greater than any one lower limit selected from the listed lower limits; or within a range that is less than or equal to any one upper limit selected from the listed upper limits, while being greater than or greater than any one lower limit selected from the listed lower limits.

[0098] The conductive polymer is a monomer unit and may contain both the monomer unit of chemical formula 4 and the monomer unit of chemical formula 5. The monomer unit of chemical formula 4 is an example of unit A mentioned above, and the monomer unit of chemical formula 5 is an example of unit B mentioned above. [ka] In chemical formula 4, R6 and R7 are independently either hydrogen or the long-chain hydrocarbon functional group, but one or more of R6 and R7 are the long-chain hydrocarbon functional group.

[0099] In other examples, R6 and R7 of chemical formula 4 can be linked together to form a divalent functional group of the following chemical formula 6.

[0100] [ka]

[0101] In chemical formula 6, L5 and L6 are independently a single bond, an alkylene group, or an alkylidene group, and R 10 and R 11 Each of these is independently either hydrogen or the long-chain hydrocarbon functional group, but R 10 and R 11 One or more of these are the long-chain hydrocarbon functional groups. 。

[0102] In chemical formulas 4 and 6, the specific types of long-chain hydrocarbon functional groups are as described above. As described above, both the first and second hydrocarbon functional groups can be applied as the long-chain hydrocarbon functional groups. In such cases, within the range of chemical formula 4, monomer units having the first hydrocarbon functional group and second monomer units having the second hydrocarbon functional group can be used, and the ratio between them can also follow the description above.

[0103] The meaning of the single bond in chemical formula 6, and the specific types of alkylene and alkylidene groups, are the same as in the case of chemical formula 3. [ka]

[0104] In chemical formula 5, R8 and R9 are each independently hydrogen or the polar functional group, but one or more of R8 and R9 may be the polar functional group. In other examples, R8 and R9 in chemical formula 5 can be linked together to form the divalent functional group of chemical formula 7 below. [ka] In chemical formula 7, L7 and L8 are independently a single bond, an alkylene group, or an alkylidene group, and R 12 and R 13 Each is independently either hydrogen or the aforementioned polar functional group, but R 12 and R 13 One or more of these may be the aforementioned polar functional groups.

[0105] The specific types of polar functional groups in chemical formulas 5 and 7 are as described above. The meaning of the single bond in chemical formula 7, and the specific types of alkylene and alkylidene groups, are the same as in the case of chemical formula 3.

[0106] For example, the ratio of the number of moles M4 of monomer units of the chemical formula 4 to the total number of moles M of monomer units of the conductive polymer, 100 × M4 / M, is equal to the ratio 100 × M L It can be adjusted within the same range as / M.

[0107] For example, the ratio M4 / M5 of the number of moles M4 of the monomer units of chemical formula 4 in a conductive polymer to the number of moles M5 of the monomer units of chemical formula 5 can be adjusted within the same range as ML / MP.

[0108] In a conductive polymer, the lower limit of the ratio 100 × (M4 + M5) / M, which is the total number of moles of monomer units of chemical formulas 4 and 5 M4 + M5 to the total number of moles of monomer units contained in the polymer M, may be approximately 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, 85 mol%, 90 mol%, or 95 mol%, and the upper limit may be approximately 100 mol%, 95 mol%, or 90 mol%. The ratio may be within a range that is greater than or greater than any one lower limit selected from the listed lower limits; or within a range that is less than or equal to any one upper limit selected from the listed upper limits; or within a range that is less than or equal to any one upper limit selected from the listed upper limits, while being greater than or greater than any one lower limit selected from the listed lower limits.

[0109] The conductive polymer may further contain other monomer units, insofar as it contains the aforementioned units in the aforementioned ratios. The lower limit of the content of the conductive polymer in the polymer layer may be approximately 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, and the upper limit may be approximately 99%, 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, or 35%. The ratio may be within a range that is greater than or greater than any one lower limit selected from the listed lower limits; or within a range that is less than or equal to any one upper limit selected from the listed upper limits; or within a range that is less than or equal to any one upper limit selected from the listed upper limits, while being greater than or greater than any one lower limit selected from the listed lower limits.

[0110] The polymer layer contains the conductive polymer, thereby enabling it to exhibit the aforementioned properties. The polymer layer may also contain any additional components, as long as it contains the conductive polymer.

[0111] For example, the polymer layer may further contain conductive material (conductive particles) along with the conductive polymer. By adding such material, the oxidation potential of the polymer layer can be adjusted, and good electrical properties can be ensured. As the conductive material, a material having appropriate conductivity can be used. For example, the conductive material may be one or more selected from carbon particles, carbon fibers, graphene, graphite, carbon black, and carbon nanotubes.

[0112] The conductive material (conductive particles) can be selected and used from the types described above. There are no particular restrictions on the form of the conductive particles; for example, they may be spherical, irregular, plate-like, or fibrous, but are not limited to these forms.

[0113] For the appropriate effect, it is necessary to control the size of the conductive material. For example, the lower limit of the average size of the conductive material (conductive particles) may be around 1 nm, 5 nm, 15 nm, 20 nm, 25 nm, or 30 nm, and the upper limit may be around 100 nm, 95 nm, 90 nm, 85 nm, 80 nm, 75 nm, 70 nm, 65 nm, 60 nm, 55 nm, 50 nm, 45 nm, 40 nm, 35 nm, or 30 nm. The average size may be within a range that is less than or equal to any one upper limit selected from the listed upper limits; or within a range that is less than or equal to any one upper limit selected from the listed upper limits, and greater than or equal to any one lower limit selected from the listed lower limits. The average size of the conductive particles is measured by the method described in "8. Measurement of the average particle size of conductive particles" in the Examples section of this specification. The closer the upper and lower limits of the average size of the conductive particles are to the average size of the conductive particles used in the examples (approximately 30 nm), the more effectively the desired effect can be achieved.

[0114] If the conductive material (conductive particles) is excessively large, it may inhibit the effect of the polymer layer (particularly the PTC effect, which leads to increased resistance).

[0115] If necessary, the conductive material may be surface-treated, taking into consideration its dispersibility and coating properties. In particular, such surface treatment can ensure stable coating properties and form a uniform polymer layer.

[0116] In such cases, a surface treatment agent having appropriate compatibility with the conductive polymer can be used as the surface treatment agent. For example, the conductive substance may be surface-treated with a polyphenol compound as the surface treatment agent. A polyphenol compound means a compound containing a structure that includes two or more linked hydroxyl groups substituted with benzene. Examples of such compounds include so-called catechol compounds (i.e., catechol or compounds containing such a structure), and examples include, but are not limited to, dopamine, polydopamine, 3,4-dihydroxyphenylalanine, norephinephrine, tannic acid, humic acid, and / or lignin.

[0117] There are no limitations on the method of surface-treating the conductive material with the surface treatment agent. For example, a method of mixing the conductive material and the surface treatment agent in a suitable solvent, or a method of synthesizing or polymerizing the surface treatment agent on the surface of the conductive material can be applied.

[0118] The content of the conductive substance can be adjusted considering the desired oxidation potential. Generally, as the content of the conductive substance in the polymer layer increases, the oxidation potential of the polymer layer decreases. Therefore, the content of the conductive substance can be adjusted considering the oxidation potential of the electrode active material and the corresponding oxidation potential of the polymer layer. For example, the lower limit of the content of the conductive substance in the polymer layer relative to 100 parts by weight of the conductive polymer may be around 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, 30 parts by weight, 40 parts by weight, 50 parts by weight, 60 parts by weight, 70 parts by weight, 80 parts by weight, 90 parts by weight, or 100 parts by weight, and the upper limit may be 150 parts by weight, 145 parts by weight, 140 parts by weight, 135 parts by weight, 130 parts by weight, 12 The content may be approximately 5 parts by weight, 120 parts by weight, 115 parts by weight, 110 parts by weight, 105 parts by weight, 100 parts by weight, 50 parts by weight, 48 parts by weight, 46 parts by weight, 44 parts by weight, 42 parts by weight, 40 parts by weight, 38 parts by weight, 36 parts by weight, 34 parts by weight, 32 parts by weight, 30 parts by weight, 28 parts by weight, 26 parts by weight, 24 parts by weight, 22 parts by weight, 20 parts by weight, 18 parts by weight, 16 parts by weight, 14 parts by weight, 12 parts by weight, 10 parts by weight, 5 parts by weight, or 1 part by weight. The content may be within a range that is less than or equal to any one upper limit selected from the listed upper limits; or within a range that is greater than or equal to any one lower limit selected from the listed lower limits; or within a range that is less than or equal to any one upper limit selected from the listed upper limits, while being greater than or equal to any one lower limit selected from the listed lower limits.

[0119] Under such ratios, the conductive material can appropriately interact with the conductive polymer to effectively form a polymer layer of the desired form.

[0120] The thickness of the polymer layer can be appropriately controlled depending on the purpose. For example, the lower limit of the thickness may be around 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 around 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 thickness may be less than or equal to any one upper limit selected from the listed upper limits, greater than or equal to any one lower limit selected from the listed lower limits, or less than or equal to any one upper limit selected from the listed upper limits, while being greater than or equal to any one lower limit selected from the listed lower limits.

[0121] This application also relates to a method for manufacturing the current collector for the electrode. The manufacturing method includes steps for controlling the properties of the conductive polymer for the desired PTC effect, etc.

[0122] The above manufacturing method may include the step of forming a polymer layer using the conductive polymer and, if necessary, a polymer solution containing the conductive substance.

[0123] In the aforementioned stage, the specific details regarding the conductive polymer and conductive substance to be used are as described above, and the coating solution can be manufactured by dissolving the polymer and / or conductive substance in a suitable solvent. At this time, the type of solvent is not particularly limited, as long as it can dissolve at least a portion of the conductive polymer.

[0124] In the above step, the lower limit of the concentration of the conductive polymer present in the polymer solution may be approximately 0.5% by weight, 1% by weight, 1.5% by weight, 2% by weight, 2.5% by weight, or 3% by weight, and the upper limit may be approximately 20% by weight, 18% by weight, 16% by weight, 14% by weight, 12% by weight, 10% by weight, 9% by weight, 8% by weight, 7% by weight, 6% by weight, 5% by weight, 4% by weight, or 3% by weight. The ratio may be within a range that is greater than or greater than any one lower limit selected from the listed lower limits, or within a range that is less than or equal to any one upper limit selected from the listed upper limits, or within a range that is less than or equal to any one upper limit selected from the listed upper limits, and greater than or equal to any one lower limit selected from the listed lower limits. Such concentrations can be changed as necessary.

[0125] The conductive polymer can be formed by known polymerization methods. For example, typical methods for producing polythiophene include methods using oxidative polymerization reactions and methods using radical reactions. A polymer layer is formed on the current collector using the polymer solution. This process typically includes the steps of coating the current collector with the polymer solution and heat-treating the coated solution. In this specification, the polymer layer formed on the current collector before the heat treatment can be referred to as a precursor. The crystallinity of the conductive polymer or the orientation of the long-chain hydrocarbon functional groups can also be controlled by the conditions of the heat treatment.

[0126] For example, the heat treatment step can be carried out in two stages. For example, the heat treatment step may include a first stage of primary heat treatment of the precursor at a temperature T1, and a second stage following the first stage of secondary heat treatment of the precursor at a temperature T2.

[0127] The conditions in the first and second stages can be adjusted to achieve the desired orientation or alignment of the functional groups of the conductive polymer and the dispersion state of the conductive material.

[0128] For example, the temperature T1 of the primary heat treatment can be adjusted within a predetermined range. For instance, the lower limit of the temperature range to which temperature T1 belongs may be around 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, 125°C, 130°C, 135°C, or 140°C, and the upper limit may be around 300°C, 290°C, 280°C, 270°C, 260°C, 250°C, 240°C, 230°C, 220°C, 210°C, 200°C, 190°C, 180°C, 170°C, 160°C, 150°C, or 140°C. The temperature range may be any range that is greater than or greater than any one lower limit selected from the listed lower limits, or greater than or greater than any one lower limit selected from the listed lower limits, and less than or equal to any one upper limit selected from the listed upper limits.

[0129] In the heat treatment step, the temperature T1 of the primary heat treatment and the temperature T2 of the secondary heat treatment can be adjusted. For example, the lower limit of the ratio T1 / T2 of the temperature ranges T1 and T2 may be around 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, or 1.2, and the upper limit may be around 5, 4.5, 4, 3.5, 3, 2.5, 2, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, or 1.1. The ratio may be within a range that is greater than or greater than any one lower limit selected from the listed lower limits; or within a range that is less than or equal to any one upper limit selected from the listed upper limits; or within a range that is greater than or greater than any one lower limit selected from the listed lower limits, while being less than or equal to any one upper limit selected from the listed upper limits. In one example, the temperature T1 of the primary heat treatment can be adjusted to be higher than the temperature T2 of the secondary heat treatment during the heat treatment stage.

[0130] The ratio M2 / M1 of the heat treatment time M1 in the primary heat treatment and the heat treatment time M2 in the secondary heat treatment can be further adjusted. For example, the lower limit of the ratio M2 / M1 may be around 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15, and the upper limit may be around 1,000, 950, 900, 850, 800, 750, 700, 650, 600, 550, 500, 450, 400, 350, 300, 290, 280, 270, 200, 150, 100, 90, 80, 70, 60, 50, 40, 30, or 20. The ratio M2 / M1 may be within a range where it is greater than or greater than any one lower limit selected from the listed lower limits; or within a range where it is less than or equal to any one upper limit selected from the listed upper limits; or within a range where it is greater than or greater than any one lower limit selected from the listed lower limits, and less than or equal to any one upper limit selected from the listed upper limits.

[0131] The lower limit of the secondary heat treatment time M2 may be approximately 0.1 hours, 0.2 hours, 0.3 hours, 0.4 hours, 0.5 hours, 0.6 hours, 0.7 hours, 0.8 hours, 0.9 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, or 18 hours, and the upper limit may be approximately 50 hours, 48 ​​hours, 46 hours, 44 hours, 42 hours, 40 hours, 38 hours, 36 hours, 34 hours, 32 hours, 30 hours, 28 hours, 26 hours, 24 hours, 22 hours, 20 hours, 18 hours, 15 hours, 10 hours, 9 hours, 8 hours, 7 hours, 6 hours, 5 hours, 4 hours, 3 hours, 2 hours, or 1.5 hours. The secondary heat treatment time M2 may be within a range that is greater than or greater than any one lower limit selected from the listed lower limits; or within a range that is less than or equal to any one upper limit selected from the listed upper limits; or within a range that is greater than or greater than any one lower limit selected from the listed lower limits, and less than or equal to any one upper limit selected from the listed upper limits.

[0132] The aforementioned heat treatment appropriately adjusts the alignment of hydrocarbon functional groups and other elements of the conductive polymer, thereby enabling the desired effect to be obtained.

[0133] The method of coating with the aforementioned coating liquid is not particularly limited, and known coating methods can be applied.

[0134] In this application, a target polymer layer and a current collector containing it are manufactured through the process described above. The process may include appropriate post-processing steps as necessary.

[0135] This application also relates to an electrode including the current collector.

[0136] As described above, the electrode may include, in order, the current collector body, the polymer layer, and the active material layer.

[0137] The polymer layer may specifically be a polymer layer included in the current collector described above and formed on the current collector body. As mentioned above, such a polymer layer can have a uniform and stable thickness due to its excellent coating properties.

[0138] As the active material layer, a commonly applied layer can be used.

[0139] Typically, the active material layer includes an electrode active material. There are no particular restrictions on the specific type of electrode active material; typically, a material that forms the positive or negative electrode can be used.

[0140] For example, if the active material layer is a positive electrode active material layer, the electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; lithium iron oxide such as LiFe3O4; or 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 as O2 (where 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 as 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); lithium nickel cobalt manganese (NCM) composite oxide, lithium nickel cobalt manganese aluminum (NCMA) composite oxide, and Li 1+c1 Mn 2-c1LiMn₂O₄ or the like in which part of Li in O₄ is substituted with alkaline earth metal ions may be used, but the active material is not limited thereto.

[0141] When the active material layer is a negative electrode active material layer, a compound capable of reversibly intercalating and deintercalating lithium can be used as the electrode active material. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of being alloyed with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, and Al alloys; SiO a (0<a<2), metal oxides capable of doping and undoping lithium such as SnO₂, vanadium oxide, and lithium vanadium oxide; or composites containing the above metallic compound and a carbonaceous material such as a Si-C composite or a Sn-C composite, and any one of these or a mixture of two or more thereof may be used.

[0142] As the negative electrode active material, a lithium thin film may be used, and low-crystalline carbon, high-crystalline carbon, or the like may be used as the carbon material. Representative examples of low-crystalline carbon include soft carbon and hard carbon, and representative examples of high-crystalline carbon include high-temperature calcined carbon such as amorphous, platy, scaly, spherical or fibrous natural graphite or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch based carbon fiber, mesocarbon microbeads, mesophase pitches, and petroleum or coal tar pitch derived cokes.

[0143] The electrode active material may be included in the active material layer in an amount of approximately 80% to 99.5% by weight or 88% to 99% by weight relative to the total weight of the active material layer, but the ratio can be changed depending on the application and design of the electrode.

[0144] The active material layer may further contain a binder. The binder plays a role in improving adhesion between the active materials and the adhesion between the active material layer and the current collector body. Examples of the binder 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, and cyanoethyl sucrose. One or more substances may be selected and used from the group consisting of sucrose, pullulan, polymethyl methacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, and polyarylate.

[0145] In one example, the binder may be included in the active material layer in an amount of 0.1 to 10 parts by weight, or 0.5 to 5 parts by weight, per 100 parts by weight of the electrode active material, but is not limited to these amounts.

[0146] The active material layer may further contain a conductive material as needed. Any known material can be used as the conductive material, as long as it does not induce a chemical change in the secondary battery and is conductive. For example, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; conductive tubes such as carbon nanotubes (CNTs); metal powders such as fluorocarbon, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide and / or conductive materials such as polyphenylene derivatives may be used.

[0147] In one example, the conductive material may be included in the active material layer in an amount of 0.1 to 20 parts by weight or 0.3 to 10 parts by weight per 100 parts by weight of the electrode active material, but is not limited to these amounts.

[0148] The active substance layer may also contain any other known components as needed, in addition to the components mentioned above.

[0149] This application also relates to a method for manufacturing the said electrode.

[0150] Such a manufacturing method of the present invention may include the step of forming the active material layer on the polymer layer on the current collector body.

[0151] There are no particular restrictions on the method for forming the active material layer on the polymer layer. Typically, the active material layer is formed by coating a slurry containing the electrode active material, binder, and conductive material onto the current collector body (polymer layer), drying it, and then rolling it. Such known methods can also be applied in this application.

[0152] This application also relates to an electrode assembly or electrochemical element including such electrodes, for example, a secondary battery.

[0153] The electrochemical element may include the electrodes as a positive electrode and / or a negative electrode. As long as the electrodes of this application are used as a negative electrode and / or a positive electrode, other configurations and manufacturing methods of the electrochemical element are not particularly limited and known methods can be applied. [Effects of the Invention]

[0154] This application relates to a current collector and its applications. This application provides a current collector and its applications that, under normal conditions, exhibit excellent electrical characteristics including low resistance, without affecting the performance and operation of a secondary battery, and under abnormal conditions, can form electrodes that can interrupt the current flow to the electrode assembly through an increase in resistance, thereby ensuring stability. [Brief explanation of the drawing]

[0155] [Figure 1] This is an example cross-sectional view of a current collector. [Figure 2] This is an illustrative cross-sectional view of an electrode. [Figure 3] This shows the NMR analysis results for the monomer from Production Example 1. [Modes for carrying out the invention]

[0156] The contents of this application will be described in detail below through examples and comparative examples, but the scope of this application is not limited by the following examples.

[0157] 1.NMR analysis method 1 ¹H-NMR analysis was performed at room temperature using an NMR spectrometer including a Bruker UltraShield spectrometer (300 MHz) with a triple-resonance 5 mm probe. The sample was diluted to a concentration of approximately 10 mg / ml in NMR measurement solvent (CDCl3), and chemical transfer was expressed in ppm.

[0158] 2. GPC (Gel Permeation Chromatograph) Molecular weight characteristics were measured using GPC (Gel permeation chromatography). A sample is placed in a 5 mL vial, and diluted with chloroform to a concentration of about 1 mg / mL. After filtering a standard calibration sample and the sample to be analyzed through a syringe filter (pore size: 0.45 μm), the molecular weight characteristics were measured. The analysis program used Empower 3 from Waters Corporation. The elution time of the sample was compared with a calibration curve to obtain the weight average molecular weight (Mw) and the number average molecular weight (Mn) respectively, and the molecular weight distribution (PDI) was calculated from the ratio thereof (Mw / Mn). The GPC measurement conditions are as follows.

[0159] <GPC Measurement Conditions> Instrument: Model 2414 from Waters Corporation Column: Three Styragel columns from Waters Corporation were used Solvent: THF (Tetrahydrofuran) Column temperature: 35°C Sample concentration: 1 mg / mL, injection volume 1 μL Standard sample: Polystyrene (Mp: 3900000, 723000, 316500, 52200, 31400, 7200, 3940, 485)

[0160] 3. Thickness Measurement The thickness of a polymer layer or the like was measured by: after cross-section processing using an ion milling () apparatus (Hitachi, IM5000), capturing an SEM (Scanning Electron Microscope) image (JEOL, JSM-7200F) to perform measurement. The cross-section forming conditions by the ion milling were set as follows: the apparatus was set to cross-section milling mode, the speed (reciprocation / min) was 3, the acceleration voltage was 6.0 kV, the discharge voltage was 15 kV, the current was 150 μA, and the processing time was 4 hours.

[0161] 4. Method for measuring oxidation potential The oxidation potential was measured by the following method. A polymer layer approximately 10 μm thick was formed on an aluminum foil (Al Foil) approximately 15 μm thick using a conductive polymer. The polymer layer was formed in the same manner as described in each example or comparative example, to a thickness of approximately 10 μm. A separation membrane and a lithium film were laminated on the polymer layer to produce a laminate consisting of aluminum foil / polymer layer / separation membrane / lithium film, and the laminate was punched out into a circle with a diameter of approximately 1.4 cm. A coin cell was manufactured using the circularly punched laminate and electrolyte (using the Welcos CR2032 coin cell kit). For the separation membrane, we used the WL20C model from Double UScope Korea, and for the lithium film, we used a lithium film with a thickness of approximately 100 μm. For the electrolyte, we used a product from Enchem (1M LiPF6 solution (solvent: EC / DMC / EMC = 3 / 4 / 3 (mass ratio), EC: Ethylene Carbonate, DMC: Dimethyl carbonate, EMC: Ethylene Methyl Carbonate)).

[0162] The oxidation potential of the coin cell was measured at 25°C using an electrochemical measuring instrument (potentiostat) (Princeton Applied Research, PARASTAT-MC). The oxidation potential was determined by measuring the cyclic voltage (CV) in the range of 1.5V to 5.5V at a scan speed of 0.17mV / sec to 0.5mV / sec.

[0163] 5. AC Impedance Resistance Measurement The AC impedance resistance was evaluated by EIS (Electrochemical Impedance Spectronization) using the same coin cell used for oxidation potential measurement (however, in this case, the thickness of the polymer layer was the same as in each example and comparative example). A voltage of 4.3V was applied to the coin cell at room temperature (25°C) for 10 minutes, and a nyquist plot was obtained by EIS measurement at 50,000Hz to 0.1Hz, and the AC impedance resistance obtained in the high frequency region (R in Equation 1) was calculated. 25 The following measurements were taken: The electrochemical instrument used for EIS measurement was a potentiostat (Princeton Applied Research, PARASTAT-MC).

[0164] AC impedance resistance at 130℃ (R in Equation 1) 130 The AC impedance resistance was evaluated using the following method: The coin cell was placed in the center of a convection oven (JEIO TECH, OF3-05W), the oven temperature was set to 130°C, and the AC impedance resistance was measured. The resistance was measured by connecting a multimeter for resistance measurement outside the oven (Fluke digital multimeter (FLUKE-87-5)) to the coin cell. Before placing the coin cell, the oven temperature was set to 130°C, and once the temperature inside the oven stabilized, the coin cell was placed in and maintained at the said temperature for approximately 10 minutes, and then the AC impedance resistance R 130 We measured it.

[0165] 6.2C Discharge Efficiency and 30-Cycle Life Measurement Coin cells (standard capacity: 200 mAh / g) were fabricated using a CR2032 standard coin cell kit (Welcos CR2032 coin cell kit). The electrodes fabricated in the examples or comparative examples were used as the positive electrode, and a lithium film (thickness: 100 μm) was used as the negative electrode. 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 electrolyte, and a PE (poly(ethylene)) separation membrane (Double UScope Korea, WL20C model) was used as the separation membrane. The 2C discharge efficiency and 30-cycle life of the coin cells were evaluated. The aforementioned 2C discharge efficiency is obtained by first determining the discharge capacity A measured while charging the coin cell at a rate of 0.5C using the CC (Constant Current) / CV (Constant Voltage) method with a charging termination voltage of 4.5V and a charging termination current of 1mA, and discharging at a rate of 0.1C using the CC (Constant Current) method with a discharge termination voltage of 3.0V, and then determining the discharge capacity B measured while charging the coin cell at a rate of 0.5C using the CC (Constant Current) / CV (Constant Voltage) method with a charging termination voltage of 4.5V and a charging termination current of 1mA, and discharging at a rate of 2C using the CC (Constant Current) method with a discharge termination voltage of 3.0V, and then substituting the discharge capacities A and B into the formula 100 × B / A.

[0166] Furthermore, the 30-cycle lifespan mentioned above was determined by performing 30 charge-discharge cycles (30 times) on the coin cell at 45°C. Specifically, the charging termination voltage was set to 4.5V and the charging termination current to 1mA, and the cell was charged at a rate of 0.2C using the CC (Constant Current) / CV (Constant Voltage) method. The discharge termination voltage was set to 3.0V, and the cell was discharged at a rate of 0.2C using the CC (Constant Current) method. This process constituted one cycle, and this cycle was repeated 30 times. The discharge capacity C1 measured after the first cycle and the discharge capacity C30 after the 30th cycle were substituted into the formula 100 × C30 / C1 to determine the 30-cycle lifespan.

[0167] 7. Measurement of discharge capacity at room temperature and high temperature Coin cells (standard capacity: 200 mAh / g) were fabricated using a CR2032 standard coin cell kit (Wellcos CR2032 coin cell kit). The electrode fabricated 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. A 1M LiPF6 solution (solvent: EC / DMC / EMC = 3 / 4 / 3 (mass ratio), EC: Ethylene Carbonate, DMC: Dimethyl carbonate, EMC: Ethylene methyl carbonate) was used as the electrolyte, and a PE (poly(ethylene)) separation membrane (Double UScope Korea, WL20C model) was used as the separation membrane. The coin cells were charged and discharged once at 25°C, and the capacity at 0.2C was recorded as the discharge capacity at 25°C (C in Equation 2). 25 ) was defined as follows. One charge / discharge cycle means that the charging termination voltage is set to 4.5V and the charging termination current to 1mA, and the battery is charged at a rate of 0.2C using the CC (Constant Current) / CV (Constant Voltage) method, and the discharge termination voltage is set to 3.0V, and the battery is discharged at a rate of 0.2C using the CC (Constant Current) method, and this process is repeated as one cycle. The discharge capacity after one charge / discharge cycle is defined as the discharge capacity at 25℃ (C in Equation 2). 25 )

[0168] Separately, discharge capacity at 130°C (C in Equation 2) 130 The discharge capacity C was measured. 25 In the process of measuring the discharge capacity, the coin cell, which was charged using the CC (Constant Current) / CV (Constant Voltage) method at a rate of 0.2C with a charge termination voltage of 4.5V and a charge termination current of 1mA, was stored at 130°C for 10 minutes, and then the discharge capacity C was measured. 130 The discharge capacity C was measured. 130 The measurement was performed by discharging a coin cell, which had been charged and stored at 130°C for 10 minutes, at a discharge termination voltage of 3.0V and a rate of 1C using the CC (Constant Current) method. The discharge was performed at 130°C.

[0169] 8. Measurement of the average particle size of conductive particles The average particle size (D50 particle size) of conductive particles was measured using a Marvern MASTERSIZER3000 in accordance with the ISO-13320 standard. Toluene was used as the solvent during measurement. When the sample (conductive particles) was dispersed in the solvent and irradiated with a laser, the laser was scattered by the dispersed sample in the solvent. Since the intensity and directionality of the scattered laser differ depending on the particle size, the average particle size can be determined by analyzing this using Mie theory. The measurement results obtained from the above analysis were converted to the particle size of a sphere having the same volume as the dispersed sample, a volume-based cumulative graph of the particle size distribution was obtained, and the particle diameter (median particle size) at 50% of the cumulative value of the graph was designated as the average particle size (D50 particle size).

[0170] Manufacturing Example 1. Synthesis of Monomer (A) The monomer of chemical formula A below can be obtained by the following method It was synthesized using [this method]. [ka] 3 g (26.28 mmol, 1 eq) of 3-methoxythiophene and 7.03 g (39.42 mmol, 1.5 eq) of triethylene glycol monomethyl ether were dissolved in 150 ml of toluene with 500 mg of p-toluenesulfonic acid (p-TsOH) (2.63 mmol, 0.1 eq) and mixed. The mixture was reacted under reflux at 120°C under a nitrogen atmosphere, and methanol produced by the reaction (transetherification) was removed using a 4A type molecular extractor packed in a soxhlet extractor. After refluxing the reaction mixture for 24 hours, it was cooled to room temperature, quenched with water, extracted with ethyl acetate, washed with brine, and dried on magnesium sulfate (MgSO4). The solvent was removed using a rotary evaporator, and the residue was purified by column chromatography using methylene chloride / hexane (2:1) elution to obtain the target compound (monomer (A)). The NMR analysis results for monomer (A) are shown in Figure 3.

[0171] Manufacturing Example 2. Synthesis of Polythiophene (B) Polythiophene (A) was prepared by dissolving 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride in 150 ml of methylene chloride. To this solution, 1 g (3.94 mmol, 0.6 eq) of 3-dodecylthiophene, 0.33 g (1.97 mmol, 0.3 eq) of 3-hexylthiophene, and 0.16 g (0.66 mmol, 0.1 eq) of monomer (A) from Production Example 1 were added, and polymerization was carried out at 30°C for 24 hours to produce polythiophene (A). The polymerization solution was placed in a permeable 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 permeable membrane was washed with methanol and dried at 60°C for 12 hours to produce polythiophene (A). The weight-average molecular weight (Mw) and water-average molecular weight (Mn) of polythiophene (A) were approximately 118,000 g / mol and 24,500 g / mol, respectively.

[0172] Manufacturing example 3. Polydopamine-coated conductive particles (A) As conductive particles, carbon black particles (IMERYS, C-NERGY(registered trademark)) SUPER C65 was used. The average particle size (D50 particle size) of the conductive particles was approximately 30 nm. DHC (Dopamine hydrochloride) (CAS No. 62-31-7) was added to a buffer solution and stirred at room temperature (approximately 25°C). The buffer solution used was BIOSESANG's 0.1 M pH 8.5 Tris-buffer product. In the final solution, the molar concentration of DHC was approximately 2 mg / mL. The conductive particles were dispersed in the buffer solution and DHC mixture to a concentration of approximately 4 mg / mL (sonication for 1 hour), and further stirred for approximately 18 hours to form a polydopamine coating layer on the conductive particles. After vacuum filtering using a paper filter, the polydopamine-coated conductive particles were obtained by vacuum drying.

[0173] Manufacturing example 4. Polydopamine-coated conductive particles (B) Conductive particles coated with polydopamine were obtained using the same method as in Production Example 3, except that carbon black particles (Aldrich, Carbon nanopowder) with an average particle size (D50 particle size) of about 100 nm were used as conductive particles.

[0174] Example 1. Polythiophene (B) from Production Example 2 and conductive particles (A) from Production Example 3 were mixed in a weight ratio of 80:20 (polythiophene:conductive particles), and the mixture was dispersed in a solvent (Chloroform) to a concentration of approximately 2% by weight to produce a coating solution. The coating solution was coated onto the current collector body using a bar coating method, and after heat treatment (drying) at 140°C for about 4 minutes, heat treatment (annealing) at 130°C for about 1 hour to form a polymer layer with a thickness of approximately 500 nm. An Al foil with a thickness of approximately 15 μm was used as the current collector body. Subsequently, an active material layer was formed on the polymer layer. The 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 (poly(vinylidene fluoride)), and NMP (N-Methyl-2-pyrrolidone) in a weight ratio of 75:1:1:23 (LiCoO2:conductive material:PVDF:NMP) to the polymer layer to a thickness of approximately 90 μm using a doctor blade. After drying at room temperature (approximately 25°C), it was further dried under vacuum conditions at 120°C. Subsequently, electrodes were manufactured by rolling to a porosity of approximately 25%.

[0175] Example 2. The current collector and electrode were manufactured in the same manner as in Example 1, except that, when forming the polymer layer, a coating solution was used which was prepared by mixing the polythiophene (B) from Production Example 2 and the conductive particles (A) from Production Example 3 in a weight ratio of 70:30 (polythiophene:conductive particles), and dispersing the mixture in a solvent (Chloroform) to a concentration of about 2% by weight.

[0176] Example 3. The current collector and electrode were manufactured in the same manner as in Example 1, except that, when forming the polymer layer, a coating solution was used which was prepared by mixing the polythiophene (B) from Production Example 2 and the conductive particles (A) from Production Example 3 in a weight ratio of 60:40 (polythiophene:conductive particles), and dispersing the mixture in a solvent (Chloroform) to a concentration of about 2% by weight.

[0177] Comparative Example 1. The current collector and electrode were manufactured in the same manner as in Example 1, except that, when forming the polymer layer, a coating solution prepared by dispersing only polythiophene (B) from Production Example 2 in a solvent (Chloroform) at a concentration of approximately 2% by weight was used.

[0178] Comparative Example 2. The current collector and electrode were manufactured in the same manner as in Example 1, except that, when forming the polymer layer, a coating solution was used which was prepared by mixing the polythiophene (B) from Production Example 2 and the conductive particles (A) from Production Example 3 in a weight ratio of 40:60 (polythiophene:conductive particles), and dispersing the mixture in a solvent (Chloroform) to a concentration of about 2% by weight.

[0179] Comparative Example 3. The current collector and electrode were manufactured in the same manner as in Example 3, except that conductive particles (B) from Manufacturing Example 4 were used instead of conductive particles (A) from Manufacturing Example 3.

[0180] Comparative Example 4. The electrodes were manufactured by directly forming the active material layer on the current collector body without forming a polymer layer.

[0181] The measurement results for the polymer layer, current collector, or electrode of the manufactured examples and comparative examples are summarized in Tables 1 and 2 below. In Tables 1 and 2 below, the 25C resistance is the AC impedance resistance (R25 in Equation 1) (Ω) at room temperature (25°C) measured by the AC impedance resistance measurement method, and the 130C resistance is the AC impedance resistance (R130 in Equation 1) (Ω) at 130°C measured by the AC impedance resistance measurement method.

[0182] Furthermore, in Tables 1 and 2 below, the 25C discharge capacity is the discharge capacity at 25°C measured by the above-mentioned room temperature and high-temperature discharge capacity measurement methods (C in Equation 2). 25 ) and the 130C discharge capacity is the discharge capacity at 130°C measured by the above-mentioned room temperature and high-temperature discharge capacity measurement method (C in Equation 2). 130 )

[0183] [Table 1]

[0184] [Table 2]

[0185] The results in Tables 1 and 2 confirm that, in the case of the electrodes according to this application, under normal conditions they exhibit low resistance, which does not affect the performance and operation of the secondary battery, and under abnormal conditions such as overcharging, high-temperature exposure, or external shock, they exhibit characteristics that ensure stability by interrupting the current flow to the electrode assembly through an increase in resistance.

Claims

1. Current collector body; and The current collector body includes a polymer layer formed on one or both sides, The polymer layer comprises a conductive polymer and conductive particles. The AC impedance resistance at 25℃ is less than 40Ω. Current collectors in which ΔR calculated by the following formula 1 is 200% or more: [Formula 1] △R=100×(R 130 -R 25 ) / R 25 In Equation 1, R 25 R is the AC impedance resistance at 25°C. 130 This is the AC impedance resistance at 130°C.

2. The current collector according to claim 1, wherein the absolute value of △C in the following equation 2 is 20% or more: [Formula 2] △C=100×(C 25 -C 130 ) / C 25 In Formula 2, C 25 is the discharge capacity at 25°C, and C 130 is the discharge capacity after storage at 130°C for 10 minutes.

3. The current collector according to claim 1, wherein the conductive polymer has long-chain hydrocarbon functional groups.

4. The current collector according to claim 3, wherein the conductive polymer includes a first hydrocarbon functional group having 10 or more carbon atoms and a second hydrocarbon functional group having 9 or fewer carbon atoms as long-chain hydrocarbon functional groups.

5. The current collector according to claim 4, wherein the ratio of the total number of moles of monomer units having a first hydrocarbon functional group to monomer units having a second hydrocarbon functional group in the conductive polymer is 70 mol% or more.

6. Number of moles M of monomer units having a second hydrocarbon functional group 2 The number of moles M of monomer units having a first hydrocarbon functional group. 1 Ratio M 2 / M 1 The current collector according to claim 5, wherein the value is in the range of 0.01 to 100.

7. The current collector according to claim 3, wherein the conductive polymer further has polar functional groups.

8. 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 3, according to claim 7: 【Chemistry 1】 In chemical formula 3, L 4 L is a single bond, an alkylene group, or an alkylidene group. 3 R is an alkylene group or alkylidene group, 5 n is a hydrogen atom or an alkyl group, and n is a number in the range of 1 to 10.

9. In conductive polymers, the number of moles M of monomer units having long-chain hydrocarbon functional groups. L The number of moles M of monomer units having polar functional groups. P Ratio M L / M P The current collector according to claim 7, wherein the value is in the range of 1 to 500.

10. The current collector according to claim 1, wherein the conductive particles are carbon particles, carbon fibers, graphene, graphite, carbon black, or carbon nanotubes.

11. The current collector according to claim 1, wherein the average size of the conductive particles is less than 100 nm.

12. The current collector according to claim 1, wherein the content of the conductive polymer in the polymer layer is in the range of 40 to 99% by weight.

13. The current collector according to claim 12, comprising 1 to 145 parts by weight of conductive particles per 100 parts by weight of conductive polymer.

14. A current collector according to any one of claims 1 to 13; and An electrode comprising an active material layer formed on the polymer layer of the current collector.

15. The electrode according to claim 14, wherein the active material layer includes a positive electrode active material.

16. An electrode assembly comprising the electrode described in claim 14.

17. A secondary battery comprising the electrode described in claim 14.

18. A secondary battery comprising the electrode assembly described in claim 16.

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