Current collector

Abstract

The present invention provides a current collector and a use thereof. The current collector and a use thereof can form an electrode that exhibits excellent electrical properties, including low resistance, under steady-state conditions, without affecting the performance and operation of a secondary battery, and that ensures stability by interrupting the flow of electricity to an electrode assembly through an increase in resistance under abnormal conditions. The present invention also provides a current collector and a use thereof that ensures excellent adhesion between layers that form the electrode.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0096260 filed on August 2, 2022, and all the contents disclosed in the document of the Korean patent application are included as part of this specification.

[0002] The present invention relates to an electrode.

Background Art

[0003] The application area of energy storage technology is expanding to mobile phones, tablets, laptops, and electric vehicles.

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

[0005] In addition, in major developed countries, in order to solve global warming and air pollution, while suppressing the production of automobiles driven by internal combustion engines, major automobile manufacturers are also promoting the development of various electric vehicles, and the importance of secondary batteries with high energy density, high discharge voltage, and output stability as their drive sources is increasing.

[0006] However, in devices and automobiles using secondary batteries as an energy source according to the above trend, the frequency of occurrence of ignition or explosion accidents due to overcharging, high-temperature exposure, or external impact is also increasing.

[0007] The main cause of such accidents is mainly a short phenomenon in which the positive electrode and the negative electrode in the electrode assembly directly contact due to an external stimulus. When the secondary battery is overcharged or exposed to high temperature or external stimulus, the short phenomenon may occur due to the shrinkage of the separator due to the rise in the internal temperature of the secondary battery or the destruction of the internal structure of the secondary battery due to an external impact.

[0008] When a short circuit occurs, the movement of lithium ions and electrons concentrates through the point where the positive and negative electrodes are in direct contact, which can accelerate internal heat generation. This is known to cause gas 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] The present invention relates to a current collector and its applications. The present invention aims to provide a current collector and its applications that can form electrodes that exhibit excellent electrical characteristics, including low resistance, in a steady state, without affecting the performance and operation of a secondary battery, and that can ensure stability by interrupting the current flow to the electrode assembly through an increase in resistance in an abnormal state.

[0010] The present invention further aims to provide a current collector and its applications that can ensure excellent adhesion between the layers forming the electrodes. [Means for solving the problem]

[0011] In this specification, the term "room temperature" means the natural temperature of a person, untouched by heating or cooling, and 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.

[0012] In this specification, if the measurement temperature affects any physical property, unless otherwise specified, the physical property is the one measured at room temperature. Unless otherwise specified, the unit of temperature used in this specification is Celsius (°C).

[0013] In this specification, the term "atmospheric pressure" refers to the natural pressure, unpressurized and undepressurized. Typically, this means a pressure of approximately 730 mmHg to 790 mmHg.

[0014] 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.

[0015] In this specification, if the measured humidity affects the physical properties, unless otherwise specified, those physical properties are those measured at standard humidity conditions.

[0016] 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%.

[0017] In this specification, the term "steady state of an electrode" or "steady state of a secondary battery" means the normal operating state of a secondary battery, such as the normal charging, discharging, or storage state of a secondary battery.

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

[0019] This invention relates to a current collector for electrodes.

[0020] The electrode current collector of the present invention may include a current collector body and a polymer layer formed on the current collector body. The electrode current collector may be used to form an electrode. For example, an electrode formed using the electrode current collector may include the electrode current collector and an active material layer formed on the polymer layer of the current collector. Figure 1 is a schematic cross-sectional view of an electrode current collector including a current collector body 100 and a polymer layer 200, and Figure 2 is a schematic cross-sectional view showing an electrode in which an active material layer 300 is formed on the polymer layer 200 of the current collector.

[0021] As shown in the drawing, in the electrode current collector or electrode, the current collector body 100 and the polymer layer 200, and the polymer layer 200 and the active material layer 300 may be in contact with each other. 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 this case, the polymer layer 200 may be present in two layers between each of the active material layers 300 present on both sides of the current collector body 100 and the current collector body 100, or it may be present in one layer between either of the active material layers 300 present on both sides and the current collector body 100.

[0022] The electrode formed from the current collector for electrodes of the present invention may be a negative electrode (anode) or a positive electrode (cathode) applied to a secondary battery.

[0023] In the current collector, the polymer layer can exhibit excellent adhesion to the current collector body.

[0024] For example, in the current collector, the lower limit of the adhesive strength of the polymer layer to the current collector body may be approximately 20gf / 20mm, 25gf / 20mm, 30gf / 20mm, 35gf / 20mm, 40gf / 20mm, 45gf / 20mm, 50gf / 20mm, 55gf / 20mm, 60gf / 20mm, 65gf / 20mm, 70gf / 20mm, 75gf / 20mm, or 80gf / 20mm, and the upper limit is The adhesive strength may be approximately 500gf / 20mm, 450gf / 20mm, 400gf / 20mm, 350gf / 20mm, 300gf / 20mm, 250gf / 20mm, 200gf / 20mm, 150gf / 20mm, 140gf / 20mm, 130gf / 20mm, 120gf / 20mm, 110gf / 20mm, 100gf / 20mm, 90gf / 20mm, 80gf / 20mm, or 70gf / 20mm. The adhesive strength may be within the range of any lower limit or greater than any of the lower limits mentioned above, or less than or equal to any upper limit, while being within the range of any lower limit or greater than any of the lower limits mentioned above. A method for evaluating such adhesive strength is summarized in the examples.

[0025] The excellent adhesive strength described above can be achieved through the use of conductive copolymers and the application of the polymer layer formation method described later.

[0026] The polymer layer of the present invention exhibits a so-called PTC (positive temperature coefficient) effect. Therefore, the polymer layer can variably control the transfer of charge through the electrode according to the temperature.

[0027] By applying such a polymer layer, the electrode having the current collector of the present invention can be applied to secondary batteries and the like, exhibiting excellent electrical properties including low resistance under normal conditions, and ensuring stability through increased resistance under abnormal conditions.

[0028] 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, and the temperature at which the resistance increases due to the PTC effect, as well as the resistance of the polymer layer before the resistance increase, affect the performance of the secondary battery. For example, if the PTC effect is excessively expressed at the steady-state temperature, the performance of the secondary battery cannot be properly expressed before stability can be ensured.

[0029] The polymer layer disclosed herein has a PTC effect, and such a PTC effect does not affect the performance of the secondary battery in a steady state, and is adjusted to ensure stability in abnormal conditions.

[0030] To achieve such a PTC effect, the crystallinity characteristics of the conductive polymer within the polymer layer may be controlled. The electrical properties of the polymer layer are affected by the crystallinity of the conductive polymer; generally, increased crystallinity leads to higher conductivity, while exposure to high temperatures impairs the crystallinity of the conductive polymer, resulting in lower conductivity and increased resistance.

[0031] In this invention, a conductive polymer having a relatively long hydrocarbon chain (long-chain hydrocarbon functional group), as described later, can be 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.

[0032] In one example, the polymer layer, the current collector or electrode to which the polymer layer is applied may have a DC resistance at 25°C below a certain level. This enables stable operation or storage of the secondary battery in a steady state. The upper limit of the DC resistance is 10 4Ω cm, 9500 Ω cm, 9000 Ω cm, 8500 Ω cm, 8000 Ω cm, 7500 Ω cm, 7000 Ω cm, 6500 Ω cm, 6000 Ω cm, 5500 Ω cm, 5000 Ω cm, 4500 Ω cm cm, 4000Ω cm, 3500Ω cm, 3000Ω cm, 2500Ω cm, 2000Ω cm, 1500Ω cm, 1000Ω cm, 950Ω cm, 900Ω cm, 850Ω cm, 800Ω cm, 7 The DC resistance may be approximately 50Ω·cm, 700Ω·cm, 650Ω·cm, 600Ω·cm, 550Ω·cm, 500Ω·cm, 450Ω·cm, 400Ω·cm, or 350Ω·cm, and its lower limit may be approximately 10Ω·cm, 50Ω·cm, 100Ω·cm, 150Ω·cm, 200Ω·cm, 250Ω·cm, 300Ω·cm, 350Ω·cm, 400Ω·cm, 450Ω·cm, 500Ω·cm, 550Ω·cm, or 600Ω·cm. The DC resistance may be within or below any of the upper limits mentioned above, or within or above any of the lower limits mentioned above, while being within or above. The DC resistance can be measured for a coin cell manufactured by applying the polymer layer as described in the examples in this specification.

[0033] In one example, the polymer layer, the current collector or electrode to which the polymer layer is applied may have an AC impedance resistance of a certain level or less at 25°C. This may enable stable operation or storage of the secondary battery in a steady state. The upper limit of the AC impedance resistance is 10 3The resistance may be around Ω, 950Ω, 900Ω, 850Ω, 800Ω, 750Ω, 700Ω, 650Ω, 600Ω, 550Ω, 500Ω, 450Ω, 400Ω, 350Ω, 300Ω, 250Ω, 200Ω, 150Ω, 100Ω, 95Ω, 90Ω, 85Ω, 80Ω, 75Ω, 70Ω, 65Ω, 60Ω, 55Ω, or 50Ω, and the lower limit may be around 10Ω, 15Ω, 20Ω, 25Ω, 30Ω, 35Ω, 40Ω, 450Ω, 50Ω, 55Ω, 60Ω, 65Ω, 70Ω, 75Ω, 80Ω, or 85Ω. The AC impedance resistance may be within the range of any upper limit of the aforementioned upper limits or less than or equal to any upper limit of the aforementioned upper limits, while being within the range of any lower limit of the aforementioned lower limits or greater than or equal to any lower limit of the aforementioned lower limits. The AC impedance resistance can be measured for a coin cell manufactured by applying the polymer layer as described in the examples herein.

[0034] By indicating the DC resistance and / or AC impedance resistance, the secondary battery to which the electrode current collector is applied may operate and be stored stably in a steady state.

[0035] The current collector of the present invention exhibits increased resistance under abnormal conditions, thereby interrupting the current flow to the electrode assembly and ensuring stability.

[0036] The polymer layer, the current collector or electrode to which the polymer layer is applied, can exhibit characteristics such that ΔR1 in the following formula 1 is above a certain level.

[0037] [Formula 1] △R1=Max{(R n+5 / R n ) / 5}

[0038] In Equation 1, R n R is the DC resistance at any temperature n°C within the range of 25°C to 135°C. n+5 This is the DC resistance at a temperature 5°C higher than the aforementioned temperature n°C ((n+5)°C), and Max{(R n+5 / R n) / 5} was confirmed within the temperature range of 25°C to 135°C (R n n+5 / R n ) / 5 is the maximum value among the values within this range.

[0039] The method for measuring ΔR1 in Equation 1 is described in the examples. In the method for confirming the ΔR1, the initial temperature is 25°C and the final temperature is 135°C. While increasing the temperature by 5°C at the initial temperature of 25°C, the DC resistance is measured at each temperature to confirm the R n+5 and R n . For example, when n is 90, R 95 / R 90 is the ratio of the DC resistance at 95°C to the DC resistance at 90°C. When ΔR1 shows a certain level or more at any temperature within the temperature range of 25°C to 135°C, it means that the resistance rises relatively rapidly at any temperature within the said temperature range.

[0040] The lower limit of the ΔR1 may be 100 Ω·cm / °C, 150 Ω·cm / °C, 200 Ω·cm / °C, 250 Ω·cm / °C, 300 Ω·cm / °C, 350 Ω·cm / °C or 400 Ω·cm / °C, and its upper limit may be about 1,000 Ω·cm / °C, 950 Ω·cm / °C, 900 Ω·cm / °C, 850 Ω·cm / °C, 800 Ω·cm / °C, 750 Ω·cm / °C, 700 Ω·cm / °C, 650 Ω·cm / °C, 600 Ω·cm / °C, 550 Ω·cm / °C, 500 Ω·cm / °C, 450 Ω·cm / °C, 400 Ω·cm / °C, 350 Ω·cm / °C, 300 Ω·cm / °C or 250 Ω·cm / °C. The ΔR1 may be within the range above or exceeding any of the aforementioned lower limits, or while being above or exceeding any of the aforementioned lower limits, it may be within the range below or less than any of the aforementioned upper limits.

[0041] The temperature at which the ΔR1 within the said range is confirmed, that is, the R in Equation 1 nThe temperature in this range may be a range. This temperature range is very important in terms of ensuring stable operation and stability of the secondary battery. That is, if the temperature is within the steady-state temperature range of the secondary battery, a temperature rise at that temperature will adversely affect the performance of the secondary battery. n The lower limit of the temperature may be around 80°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C, or 95°C, and the upper limit may be around 200°C, 190°C, 180°C, 170°C, 160°C, 150°C, 140°C, 130°C, 120°C, 110°C, 100°C, or 90°C. The temperature may be above or below any of the lower limits mentioned above, or above or above any of the lower limits mentioned above, while being below or below any of the upper limits mentioned above.

[0042] By controlling the temperature range so that resistance increases within that range, stable operation and storage in a steady state, as well as stable power interruption in abnormal conditions, can be achieved. For example, by adjusting the temperature range, stable storage is possible even when secondary batteries are stored at relatively high temperatures.

[0043] The polymer layer, the current collector or electrode to which the polymer layer is applied, can exhibit the characteristic that ΔR2 in the following formula 2 is above a certain level.

[0044] [Formula 2] △R² = Max{(R z+5 / R z ) / 5}

[0045] In Equation 2, R z R is the AC impedance resistance at any temperature n°C within the range of 25°C to 135°C. z+5 This is the AC impedance resistance at a temperature 5°C higher than the aforementioned temperature n°C ((n+5)°C), and Max{(R z+5 / R z ) / 5} was confirmed within the temperature range of 25℃ to 135℃ (R z+5 / R z ) / 5 is the maximum value among them.

[0046] The method for measuring ΔR2 in Equation 2 is described in the examples. In the method for confirming ΔR2, the initial temperature is 25°C and the final temperature is 135°C. The AC impedance resistance is measured at each temperature while increasing the temperature by 5°C at an initial temperature of 25°C to determine Rz. +5 and R z Check this. For example, if n is 90, R 95 / R 90 This is the ratio of the AC impedance resistance at 95°C to the AC impedance resistance at 90°C. If ΔR2 is 10Ω / °C or higher at any temperature within the temperature range of 25°C to 135°C, it means that the resistance of the polymer layer or electrode increases relatively rapidly at any temperature within that temperature range.

[0047] The lower limit of ΔR2 may be approximately 10Ω / ℃, 12Ω / ℃, 14Ω / ℃, 16Ω / ℃, 18Ω / ℃, 20Ω / ℃, 22Ω / ℃, 24Ω / ℃, 26Ω / ℃, 28Ω / ℃, 30Ω / ℃, or 33Ω / ℃, and its upper limit may be approximately 100Ω / ℃, 95Ω / ℃, 90Ω / ℃, 85Ω / ℃, 80Ω / ℃, 75Ω / ℃, 70Ω / ℃, 65Ω / ℃, 60Ω / ℃, 55Ω / ℃, 50Ω / ℃, 45Ω / ℃, 40Ω / ℃, 35Ω / ℃, 30Ω / ℃, or 25Ω / ℃. The range of ΔR2 may be greater than or equal to any of the lower limits mentioned above, or greater than or equal to or greater than any of the lower limits mentioned above, while being less than or equal to any of the upper limits mentioned above.

[0048] By ensuring the aforementioned characteristics, the resistance increases under abnormal conditions, thereby interrupting the current flow and ensuring stability.

[0049] As in the case of the formula, the temperature at which the aforementioned ΔR2 is confirmed, i.e., R zThe temperature range is of great importance. The lower limit of the temperature may be around 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C, or 95°C, and the upper limit may be around 200°C, 190°C, 180°C, 170°C, 160°C, 150°C, 140°C, 130°C, 120°C, 110°C, 100°C, or 90°C. The temperature may be above or below any of the lower limits mentioned above, or above or above any of the lower limits mentioned above, while being below or below any of the upper limits mentioned above.

[0050] By controlling the temperature range so that resistance increases within that range, stable operation and storage in a steady state, as well as stable power interruption in abnormal conditions, can be achieved. For example, by adjusting the temperature range, stable storage is possible even when secondary batteries are stored at relatively high temperatures.

[0051] The polymer layer, the current collector or electrode to which the polymer layer is applied, or the secondary battery to which the polymer layer is applied can exhibit the characteristic that the absolute value of △R3 in the following equation 3 is within a certain range.

[0052] [Formula 3] △R3 = 100 × (C1 - C2) / C1

[0053] In Equation 3, C1 is the discharge capacity at room temperature (approximately 25°C), and C2 is the discharge capacity after storage at 70°C for 60 hours. C1 and C2 in Equation 3 are the discharge capacities of the polymer layer measured relative to the coin cell, and the specific method for measuring these capacities is summarized in the Examples.

[0054] The upper limit of the absolute value of △R3 in Equation 3 may be approximately 10%, 9.5%, 9%, 8.5%, 8%, 7.5%, 7%, 6.5%, 6%, 5.5%, 5%, 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, 1.5%, 1%, or 0.5%, and its lower limit may be approximately 0%, 0.5%, or 1.5%. The absolute value of △R3 may be within the range of any upper limit or less than any of the upper limits mentioned above, or greater than or greater than any lower limit or greater than any of the lower limits mentioned above, while being within the range of any upper limit or less than any of the upper limits mentioned above. A △R3 within the above range means that stable operation and storage are possible even when the secondary battery is operated and stored at relatively high temperatures within the steady-state range.

[0055] The polymer layer, the current collector or electrode to which the polymer layer is applied, or the secondary battery to which the polymer layer is applied can exhibit the characteristic that the absolute value of △R4 in the following formula 4 is 50% or more.

[0056] [Formula 4] △R4 = 100 × (C 1- C3) / C1

[0057] In Equation 4, C1 is the discharge capacity at room temperature (approximately 25°C), and C3 is the discharge capacity after storage at 130°C for 10 minutes.

[0058] In Equation 4, C1 and C3 are the discharge capacities measured for a coin cell to which the polymer layer is applied, and the specific method for measuring these capacities is summarized in the Examples.

[0059] The lower limit of the absolute value of △R4 in Equation 4 may be around 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, or 76%, and its upper limit may be around 200%, 180%, 160%, 140%, 120%, 100%, 95%, 90%, 85%, 80%, 75%, 70%, 65%, or 60%. The absolute value of △R4 may be within the range of being greater than or exceeding any of the lower limits mentioned above, or it may be greater than or exceeding any of the lower limits mentioned above, while being less than or equal to any of the upper limits mentioned above. A △R4 within the above range means that stability is effectively ensured by an increase in resistance in an abnormal state of the secondary battery.

[0060] The aforementioned characteristics can be achieved through the introduction of a polymer layer, as described later.

[0061] The current collector body may be any current collector body that is normally used as a positive or negative electrode current collector body, without any particular restrictions.

[0062] The current collector body is not particularly limited in type, size, and shape, as long as it is conductive and does not induce chemical changes in the applied device, such as a secondary battery. Examples of materials that can be used as the current collector body include copper, aluminum, stainless steel, nickel, titanium, or calcined carbon, or materials such as copper, aluminum, or stainless steel with a surface treatment of carbon, nickel, titanium, or silver. The current collector body may 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 polymer layers or active material layers.

[0063] Such current collector bodies may typically have a thickness in the range of 3 μm to 500 μm, but are not limited to this range.

[0064] A polymer layer is present on one or both sides of the current collector body.

[0065] 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 the range of being greater than or exceeding any of the lower limits mentioned above, or less than or equal to any of the upper limits mentioned above, while being within the range of being greater than or exceeding any of the lower limits mentioned above.

[0066] The polymer layer does not have to be a so-called electrode active material layer. Therefore, the content of the electrode active material within the polymer layer may be controlled. For example, the upper limit of the content of the electrode active material within the polymer layer may be approximately 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 or below any of the upper limits mentioned above, or within or above any of the lower limits mentioned above, while being within or above any of the lower limits mentioned above. The specific types of the electrode active material will be described later.

[0067] The polymer contained in the polymer layer may be a conductive polymer. A conductive polymer is a polymer that exhibits conductivity through a conjugated system of polymer chains and / or doping, as is well known.

[0068] The conductive polymer may also be a conductive copolymer. A conductive copolymer is a type of conductive polymer and is distinguished from a homopolymer in that it is a conductive polymer containing two or more monomer units.

[0069] The aforementioned properties can be effectively ensured through the use of specific conductive copolymers described later, and through the effective control of the crystallinity and oxidation potential of said copolymers.

[0070] The oxidation potential of the conductive copolymer or polymer layer may be adjusted depending on the purpose. A method for measuring the oxidation potential is summarized in the examples of this specification. The oxidation potential varies depending on the electrode and electrolyte applied to the measurement, but in this specification, the oxidation potential refers to lithium and lithium ions (Li / Li + This is the oxidation potential measured with respect to ). In the present invention, desired characteristics can be ensured by adjusting the oxidation potential measured by the measurement method described in the following examples.

[0071] The lower limit of the oxidation potential may be approximately 2V, 2.1V, 2.2V, 2.3V, 2.4V, 2.5V, 2.6V, 2.7V, 2.8V, 2.9V, 3V, 3.1V, 3.2V, 3.3V, 3.4V, 3.5V, 3.6V, or 3.7V, and the upper limit may be approximately 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 the range of any upper limit or less than any of the upper limits mentioned above, and within the range of any lower limit or greater than any of the lower limits mentioned above. Alternatively, it may be less than or equal to any of the upper limits, but greater than or equal to any of the lower limits mentioned above. By adjusting the oxidation potential to the same range as described above, the desired characteristics can be effectively ensured.

[0072] The conductive copolymer may have a weight-average molecular weight within a predetermined range. The lower limit of the weight-average molecular weight of the conductive copolymer may be approximately 30,000 g / mol, 35,000 g / mol, 40,000 g / mol, 45,000 g / mol, 50,000 g / mol, 55,000 g / mol, or 60,000 g / mol, and the upper limit may be approximately 200,000 g / mol, 150,000 g / mol, 100,000 g / mol, 95,000 g / mol, 90,000 g / mol, 85,000 g / mol, 80,000 g / mol, 75,000 g / mol, 70,000 g / mol, 65,000 g / mol, 60,000 g / mol, 55,000 g / mol, or 50,000 g / mol. The weight-average molecular weight may be less than or equal to any of the upper limits mentioned above, greater than or equal to any of the lower limits mentioned above, or less than or equal to any of the upper limits mentioned above, while being greater than or equal to any of the lower limits mentioned above. By using a conductive copolymer having such a weight-average molecular weight, polymer layers and electrodes with desired properties can be effectively formed.

[0073] The conductive copolymer may have a number-average molecular weight within a predetermined range. The lower limit of the number-average molecular weight of the conductive copolymer may be approximately 5,000 g / mol, 6,000 g / mol, 7,000 g / mol, 8,000 g / mol, 9,000 g / mol, 10,000 g / mol or 11,000 g / mol, 12,000 g / mol, 13,000 g / mol, 14,000 g / mol, 15,000 g / mol, 16,000 g / mol, 17,000 g / mol or 18,000 g / mol, and the upper limit may be 100,000 g / mol, 95,000 g / mol, 90,000 g / mol, 8 It may also be around 5,000 g / mol, 80,000 g / mol, 75,000 g / mol, 70,000 g / mol, 65,000 g / mol, 60,000 g / mol, 55,000 g / mol, 50,000 g / mol, 45,000 g / mol, 40,000 g / mol, 35,000 g / mol, 30,000 g / mol, 25,000 g / mol, 20,000 g / mol, 15,000 g / mol, 14,000 g / mol, 13,000 g / mol, 12,000 g / mol, or 11,000 g / mol. The number-average molecular weight may be less than or equal to any of the upper limits mentioned above, greater than or equal to any of the lower limits mentioned above, or less than or equal to any of the upper limits mentioned above, while being greater than or equal to any of the lower limits mentioned above. By using a conductive copolymer having such a number-average molecular weight, polymer layers and electrodes with desired properties can be effectively formed.

[0074] The molecular weight distribution of the conductive copolymer, i.e., the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (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 or below any of the upper limits mentioned above, or within or above any of the lower limits mentioned above, or within or below any of the upper limits mentioned above, while being within or above any of the lower limits mentioned above. By using a conductive copolymer having such a molecular weight distribution, polymer layers and electrodes with desired properties can be effectively formed.

[0075] The polymer layer may consist solely of the conductive copolymer, or it may further consist of the conductive copolymer and other necessary additives. In one example, the lower limit of the content of the conductive copolymer in the polymer layer may be approximately 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95% by weight, based on the total weight of the polymer layer, and the upper limit may be approximately 100%, 95%, or 90% by weight, based on the total weight of the polymer layer. The ratio may be within the range of being above or above any of the lower limits mentioned above, or below or below any of the upper limits mentioned above, while being within the range of being above or above any of the lower limits mentioned above.

[0076] As the conductive copolymer, a conductive copolymer having a polar functional group may be used. That is, the conductive copolymer may contain monomer units having the polar functional group. The monomer unit may be a thiophene monomer unit, and such a monomer unit is sometimes called the first unit.

[0077] In this specification, a monomer unit means a form in which a monomer is polymerized and included in a polymer, and a thiophene monomer means a monomer containing a thiophene skeleton as a thiophene-based monomer.

[0078] 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 shown in Formula 3 below. In one example, the functional group shown in Formula 3 below may be used as the polar functional group.

[0079] [ka]

[0080] 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 hydrogen or an alkyl group; and n is any number.

[0081] In chemical formula 3, a single bond at L4 means that L4 is absent, and the oxygen atom between L4 and L3 is directly linked to the second monomer.

[0082] In chemical formula 3, the alkyl group R5 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, and 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 optionally be substituted with at least one substituent.

[0083] In this specification, the term alkylene group refers to a divalent functional group formed by the removal of hydrogen atoms from two different carbon atoms in an alkane, and the term alkylidene group refers to a divalent functional group formed by the removal of two hydrogen atoms from one carbon atom in an alkane.

[0084] 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, and may also 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 optionally be substituted with at least one substituent.

[0085] 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, and may also be methylidene, ethylidene, or propyridene groups. The alkylidene groups may be linear, branched, or cyclic, and may be linear or branched as appropriate. The alkylidene groups may optionally be substituted with at least one substituent.

[0086] In 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 aforementioned n may be less than or equal to any of the upper limits mentioned above, while being greater than or equal to any of the lower limits mentioned above.

[0087] Through the application of the aforementioned polar functional groups, the polymer layer can be bonded to other layers with appropriate bonding force, and such conductive copolymer layers can be uniformly formed to efficiently achieve the desired protective function.

[0088] To maximize the effects described above, the ratio of the polar functional groups may be controlled.

[0089] For example, the polar functional groups may be present such that the EP value according to the following formula A is within a predetermined range.

[0090] [Formula A] EP = Mn / P

[0091] In formula A, Mn is the number-average molecular weight of the conductive copolymer, and P is the number of moles of monomer units containing the polar functional group in the conductive copolymer.

[0092] The lower limit of the EP value may be around 6,000, 6,500, 7,000, 7,500, 8,000, 8,500, 9,000, 9,500, 10,000, 15,000, 20,000, or 25,000, and the upper limit may be 100,000, 95,000, 90,000, 85,000, 80,0 The EP value may be approximately 00, 75,000, 70,000, 65,000, 60,000, 55,000, 50,000, 45,000, 40,000, 35,000, 30,000, 25,000, 20,000, 15,000, 10,000, 9,500, 9,000, 8,500, or 8,000. The EP value may be within the range of less than or equal to any of the upper limits mentioned above, or within the range of greater than or equal to any of the lower limits mentioned above, or within the range of greater than or equal to any of the lower limits mentioned above while being less than or equal to any of the upper limits mentioned above.

[0093] When the presence of polar functional groups is controlled within the aforementioned range, the desired adhesive strength can be achieved, and a uniform polymer layer can be effectively formed.

[0094] The range of the number-average molecular weight of the conductive copolymer is as described above.

[0095] The conductive copolymer may also be a thiophene copolymer.

[0096] In this specification, the term "thiophene copolymer" means a copolymer containing thiophene monomer units at a certain level or higher. The lower limit of the molar ratio of thiophene monomer units to the total number of moles of monomer units contained in the thiophene copolymer 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 greater than or greater than any of the lower limits mentioned above, or less than or equal to any of the upper limits mentioned above, while being greater than or greater than any of the lower limits mentioned above.

[0097] As stated above, in this specification, a monomer unit means a form in which a monomer is polymerized and included in a polymer, and a thiophene monomer means a thiophene-based monomer that contains a thiophene skeleton.

[0098] The conductive copolymer of the present invention may contain a long-chain hydrocarbon functional group or a monomer unit having the long-chain hydrocarbon functional group (hereinafter sometimes referred to as a second unit). The monomer having the long-chain hydrocarbon functional group may be a thiophene monomer.

[0099] In other words, the conductive copolymer may include the second unit along with the monomer unit having the polar functional group described above (for example, the thiophene monomer unit).

[0100] 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.

[0101] 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 above or above any of the lower limits mentioned above, or below or below any of the upper limits mentioned above, while being within the range of being above or above any of the lower limits mentioned above.

[0102] The 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 may have a straight-chain structure or a branched-chain structure, but 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 range described above. For example, if the branched-chain structure is a 2-ethylhexyl group, the number of carbon atoms constituting the longest straight chain is 6.

[0103] Examples of the long-chain hydrocarbon functional group include at least one 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.

[0104] 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).

[0105] 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 in a linear or branched chain structure, but in the case of a branched chain, the number of carbon atoms constituting the longest linear chain in the branched chain structure may be within the range described above.

[0106] The aforementioned long-chain hydrocarbon functional group, which is an alkyl group, alkenyl group, alkynyl group, alkoxy group, alkylcarbonyl group, or alkylcarbonyloxy, may optionally be substituted with at least one substituent.

[0107] Such long-chain hydrocarbon functional groups are functional groups that can impart appropriate fluidity (mobility) to the monomer or the conductive copolymer itself during the polymerization process of the conductive copolymer. Monomers containing such long-chain hydrocarbon functional groups impart appropriate fluidity to the monomer mixture and further diffuse within the monomer mixture, enabling polymerization to occur with excellent efficiency. In addition, conductive copolymers having long-chain hydrocarbon functional groups can ensure that a polymer layer is stably and uniformly formed between the current collector body and the active material layer through appropriate fluidity.

[0108] The long-chain hydrocarbon functional groups can be appropriately oriented during the drying or annealing process applied in the polymer layer formation process, thereby imparting a PTC effect suitable for copolymers.

[0109] When a certain amount of thermal energy is applied to the long-chain hydrocarbon functional group, it begins to vibrate due to the heat. This vibration (thermal vibration) promotes the dedoping of anions bonded to the copolymer, thereby inducing an increase in resistance. The temperature at which the thermal vibration occurs may be controlled by the length and / or amount of the long-chain hydrocarbon functional group. For example, at the same temperature, the thermal vibration of a relatively long chain is greater than that of a relatively short chain, and thus the longer chain can induce a resistance-increasing effect at a relatively lower temperature. Therefore, the desired PTC effect can be set by controlling the length and / or ratio of the long-chain hydrocarbon functional group.

[0110] For example, in order to appropriately realize the above effect, the molar ratio of monomer units having the long-chain hydrocarbon functional group (second unit) to the total number of monomer units of the conductive copolymer may be adjusted. For example, the lower limit of the molar ratio may be around 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 around 99 mol%, 95 mol%, 90 mol%, 85 mol%, or 80 mol%. The ratio may be within the range of being above or above any of the lower limits mentioned above, or below or below any of the upper limits mentioned above, while being within the range of being above or above any of the lower limits mentioned above.

[0111] When a conductive copolymer contains both the long-chain hydrocarbon functional group and the polar functional group, the number of moles of the polar functional group and the long-chain hydrocarbon functional group may be controlled to ensure appropriate effects.

[0112] For example, the lower limit of the ratio (M1 / M2) of the number of moles of long-chain hydrocarbon functional groups (M1) to the number of moles of polar functional groups (M2) in the conductive copolymer may be around 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, or 8.5, and the upper limit may be around 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, or 4. The ratio M1 / M2 may be within the range of any upper limit or less than any of the upper limits mentioned above, or within the range of any lower limit or more than any of the lower limits mentioned above, while being within the range of any lower limit or more than any of the lower limits mentioned above.

[0113] In the conductive copolymer, the lower limit of the ratio (M2 / M1) of the second unit (M2) to the number of moles of the first unit (M1) may be approximately 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, or 8.5, and the upper limit may be approximately 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, or 4. The ratio M2 / M1 may be within the range of any upper limit or less than any of the upper limits mentioned above, or within the range of any lower limit or more than any of the lower limits mentioned above, while being within the range of any lower limit or more than any of the lower limits mentioned above.

[0114] The lower limit of the ratio of the total number of moles of the first and second units to the total number of moles of all monomer units in the conductive copolymer 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 above or above any of the lower limits mentioned above, or below or below any of the upper limits mentioned above, while being within the range of being above or above any of the lower limits mentioned above.

[0115] In one example, the conductive copolymer may include the monomer unit shown in Chemical Formula 1 below as the thiophene monomer unit.

[0116] [ka]

[0117] In chemical formula 1, R1 and R2 are each independently hydrogen, the polar functional group, or the long-chain hydrocarbon functional group, but at least one of R1 and R2 may be the polar functional group or the long-chain hydrocarbon functional group.

[0118] In other examples, in chemical formula 1, R1 and R2 can be linked together to form the divalent functional group in chemical formula 2 below.

[0119] [ka]

[0120] In chemical formula 2, each oxygen atom may be bonded to the carbon atom to which R1 is bonded and the carbon atom to which R2 is bonded in chemical formula 1.

[0121] In chemical formula 2, L1 and L2 are each independently a single bond, an alkylene group, or an alkylidene group, and R3 and R4 are each independently hydrogen, a polar functional group, or a long-chain hydrocarbon functional group, but at least one of R3 and R4 is a polar functional group or a long-chain hydrocarbon functional group.

[0122] The specific types of polar functional groups and long-chain hydrocarbon functional groups in chemical formulas 1 and 2 are as described above.

[0123] Furthermore, the meaning of L1 or L2 being a single bond in chemical formula 2 is the same as the case of L4 in chemical formula 3.

[0124] In Chemical Formula 2, the specific types of alkylene and alkylidene groups in L1 and L2 are the same as those in Chemical Formula 3.

[0125] The lower limit of the molar ratio of the monomer units in Formula 1 to the total number of moles of monomer units in the conductive copolymer 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 greater than or greater than any of the lower limits mentioned above, or less than or equal to any of the upper limits mentioned above, while being greater than or greater than any of the lower limits mentioned above.

[0126] The conductive copolymer may simultaneously contain the monomer units of formula 4 and the monomer units of formula 5 below as monomer units.

[0127] The monomer unit in Formula 4 below is an example of the second unit described above, and the monomer unit in Formula 5 below is an example of the first unit described above.

[0128] [ka]

[0129] In chemical formula 4, R6 and R7 are each independently either hydrogen or the long-chain hydrocarbon functional group, but at least one of R6 and R7 is the long-chain hydrocarbon functional group. The specific details of the long-chain hydrocarbon functional group are as described above.

[0130] In other examples, R6 and R7 in the above formula 4 may be linked together to form the divalent functional group in the following formula 6.

[0131] [ka]

[0132] 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 is independently a hydrogen atom or a long-chain hydrocarbon functional group, but R 10 and R 11 At least one of these is a long-chain hydrocarbon functional group. The specific types of long-chain hydrocarbon functional groups in chemical formulas 4 and 6 are as described above.

[0133] In chemical formula 6, the meaning of the single bond and the specific types of alkylene and alkylidene groups are the same as in chemical formula 3.

[0134] [ka]

[0135] In chemical formula 5, R8 and R9 are each independently hydrogen or the polar functional group, but at least one of R8 and R9 may be the polar functional group. The specific types of the polar functional group are as described above.

[0136] In other examples, R8 and R9 in the above formula 5 may be linked together to form the divalent functional group in the following formula 7.

[0137] [ka]

[0138] 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 a hydrogen atom or a polar functional group, and R 12 and R 13 At least one of these may be a polar functional group. The specific types of polar functional groups in chemical formulas 5 and 7 are as described above.

[0139] Furthermore, the meaning of the single bond in Chemical Formula 7, and the specific types of alkylene and alkylidene groups, are the same as in Chemical Formula 3.

[0140] For example, the lower limit of the ratio of the number of moles of monomer units in formula 4 to the total number of moles of monomer units in the conductive copolymer 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 99 mol%, 95 mol%, 90 mol%, 85 mol%, or 80 mol%. The ratio may be within the range of being above or above any of the lower limits mentioned above, or below or below any of the upper limits mentioned above, while being within the range of being above or above any of the lower limits mentioned above.

[0141] For example, the lower limit of the ratio (M4 / M5) of the number of moles of monomer units in formula 4 (M4) to the number of moles of monomer units in formula 5 (M5) within a conductive copolymer may be approximately 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, or 8.5, and the upper limit may be approximately 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, or 4. The ratio M4 / M5 may be within the range of being greater than or exceeding any of the lower limits mentioned above, or within the range of being less than or equal to any of the upper limits mentioned above, or within the range of being greater than or exceeding any of the lower limits mentioned above while being less than or equal to any of the upper limits mentioned above.

[0142] In a conductive copolymer, the lower limit of the ratio of the total number of moles of monomer units in formulas 4 and 5 to the total number of moles of monomer units contained in the copolymer 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 of the lower limits mentioned above, or within the range of being less than or equal to any of the upper limits mentioned above, or within the range of being greater than or exceeding any of the lower limits mentioned above while being less than or equal to any of the upper limits mentioned above.

[0143] The conductive copolymer may further contain other monomer units, in addition to the units described above in the aforementioned ratios.

[0144] The polymer layer contains the conductive copolymer, thereby exhibiting the properties described above. If the polymer layer contains the conductive copolymer, it may also contain any additional components.

[0145] The lower limit of the thickness of the polymer layer may be approximately 10 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, or 500 nm, and the upper limit may be approximately 2 μm, 1.5 μm, 1 μm, 950 nm, 900 nm, 850 nm, 800 nm, 750 nm, 700 nm, 650 nm, 600 nm, 550 nm, 500 nm, 450 nm, 400 nm, 350 nm, or 300 nm. The thickness may be within the range of being greater than or exceeding any of the lower limits mentioned above, or within the range of being less than or equal to any of the upper limits mentioned above, or within the range of being greater than or exceeding any of the lower limits mentioned above while being less than or equal to any of the upper limits mentioned above.

[0146] The present invention further relates to a method for manufacturing an electrode current collector. The manufacturing method includes a step for controlling the crystallinity of the conductive copolymer in order to ensure a desired PCT effect and adhesive strength.

[0147] The above manufacturing method may include a step of forming a polymer layer using a polymer solution containing the conductive copolymer.

[0148] In the aforementioned stage, the specific description of the conductive copolymer to be used is as described above, and the coating solution may be manufactured by dissolving the copolymer in a suitable solvent. In this case, the type of solvent is not particularly limited as long as it can dissolve at least a portion of the conductive copolymer.

[0149] In the above step, the lower limit of the concentration of the conductive copolymer 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 the range of being above or above any of the lower limits mentioned above, or within the range of being below or below any of the upper limits mentioned above, or within the range of being above or above any of the lower limits mentioned above, while being below or below any of the upper limits mentioned above. Such concentrations may be changed as necessary.

[0150] The conductive copolymer may be formed by known polymerization methods. For example, typical methods for producing polythiophene include methods using oxidative polymerization reactions and methods using radical reactions.

[0151] A polymer layer is formed on the current collector body using the manufactured polymer solution. This process typically includes the steps of coating the current collector body with the polymer solution and annealing the coated solution. The crystallinity of the conductive copolymer may also be controlled by the annealing conditions during this process.

[0152] For example, the annealing temperature T and / or time H may be adjusted.

[0153] For example, the lower limit of the temperature T 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, or 125°C, and the upper limit may be around 200°C, 195°C, 190°C, 185°C, 180°C, 175°C, 170°C, 165°C, 160°C, 155°C, 150°C, 145°C, 140°C, 135°C, 130°C, 125°C, 120°C, 115°C, 110°C, 105°C, 100°C, 95°C, or 90°C. The temperature may be within a range of less than or equal to any of the upper limits mentioned above, or within a range of greater than or equal to any of the lower limits mentioned above, or within a range of greater than or equal to any of the lower limits mentioned above, while being less than or equal to any of the upper limits mentioned above. Within such a range, the alignment of the long-chain hydrocarbon functional groups of the conductive copolymer can be appropriately adjusted, thereby ensuring the desired crystallinity.

[0154] To achieve the objective, the product of the annealing temperature T and time H (T × H) may be adjusted. For example, the lower limit of the product of the annealing temperature T and time H (T × H) is 10°C·hour, 15°C·hour, 20°C·hour, 25°C·hour, 30°C·hour, 35°C·hour, 40°C·hour, 45°C·hour, 50°C·hour, 75°C·hour, 100°C·hour, 110°C·hour, 120°C·hour, 130°C·hour, 150°C·hour, 160°C·hour, 170°C·hour, 180°C·hour, 190°C·hour, 200°C·hour, and 210°C. It may be around 220°C·hour or 230°C·hour, and its upper limit is 100,000°C·hour, 95,000°C·hour, 90,000°C·hour, 85,000°C·hour, 80,000°C·hour, 75,000°C·hour, 70,000°C·hour, 65,000°C·hour, 60,000°C·hour, 55,000°C·hour, 50,000°C·hour, 45,000°C·hour, 40,000°C·hour, 35,000°C·hour, 30,000°C·hour, 25 000℃・hour, 20000℃・hour, 15000℃・hour, 10000℃・hour, 9500℃・hour, 9000℃・hour, 8500℃・hour, 8000℃・hour, 7500℃・hour, 7000℃・hour, 6 500℃・hour, 6000℃・hour, 5500℃・hour, 5000℃・hour, 4500℃・hour, 4000℃・hour, 3500℃・hour, 3000℃・hour, 2500℃・hour, 2000℃・hour, 1500 °C·hour, 1400°C·hour, 1300°C·hour, 1200°C·hour, 1100°C·hour, 1000°C·hour, 900°C·hour, 800°C·hour, 700°C·hour, 600°C·hour, 500°C·hour, 400°C·hour, 300°C·hour, 200°C·hour, 100°C·hour, 90°C·hour, 80°C·hour, 70°C·hour, 60°C·hour, 50°C·hour, 45°C·hour, or approximately 40°C·hour may also be used.The aforementioned product (T × H) may be within the range of any upper limit among the aforementioned upper limits, or within the range of any lower limit among the aforementioned lower limits, or within the range of any lower limit among the aforementioned lower limits while being within the range of any lower limit among the aforementioned lower limits. Within such a range, the alignment state of the long-chain hydrocarbon functional groups of the conductive copolymer can be appropriately adjusted, thereby ensuring the desired crystallinity.

[0155] The method of applying the coating liquid is not particularly limited, and known coating methods may be applied.

[0156] In this invention, a desired polymer layer and a current collector containing it are manufactured through the above process. The above process may include appropriate post-processing steps as needed.

[0157] The present invention further relates to an electrode including a current collector. The electrode may include an active material layer formed on the polymer layer of the current collector.

[0158] A commonly applied layer may also be used as the active material layer.

[0159] Typically, the active material layer contains an electrode active material. There are no particular restrictions on the specific type of electrode active material, and typically, a material that forms the positive or negative electrode may be used.

[0160] For example, if the active material layer is the 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, or a 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 Mc2 Lithium nickel - type lithium nickelate represented by O2 (where M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, and satisfies 0.01 ≦ c2 ≦ 0.3), and chemical formula LiMn 2-c3 M c3 O2 (where M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn, and Ta, and satisfies 0.01 ≦ c3 ≦ 0.1) or lithium manganese composite oxide represented by 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 LiMn2O4 in which part of Li in the chemical formula is substituted by alkaline earth metal ions, etc., may be used, but are not limited thereto.

[0161] When the active material layer is a negative electrode active material layer, as the electrode active material, a compound capable of reversible intercalation and de - intercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon, metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy or Al alloy, metal oxides capable of doping and undoping lithium such as SiO a (0 < a < 2), SnO2, vanadium oxides, lithium vanadium oxides, etc., or composite materials containing the metal compound and the carbonaceous material such as Si - c composite or Sn - c composite, etc. may be mentioned, and any one or a mixture of two or more of these may be used.

[0162] As the negative electrode active material, a lithium thin film may be used, and as the carbon material, low-crystalline carbon and high-crystalline carbon may be used. Typical low-crystalline carbons include soft carbon and hard carbon, while typical high-crystalline carbons include amorphous, plate-like, flaky, spherical or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesocarbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch-derived cokes.

[0163] The electrode active material may be contained within 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 may be changed depending on the application and design of the electrode.

[0164] 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 butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, and cyanoethyl sucrose. At least one of the following may be selected and used: sucrose, pullulan, polymethyl methacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, and polyarylate.

[0165] 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 thereto.

[0166] The active material layer may further contain a conductive material as needed. As the conductive material, any known material can be used without particular limitation, as long as it is conductive without inducing a chemical change in the secondary battery. For example, conductive materials such as graphite such as natural graphite or artificial graphite, carbon black such as carbon black, acetylene black, Ketjen black, channel black, Panes 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 polyphenylene derivatives may be used.

[0167] The conductive material may, in one example, be included 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, or it may be included in the active material layer, but is not limited thereto.

[0168] The active material layer may also contain, in addition to the aforementioned components, any other known components as needed.

[0169] In the electrode, the active material layer can exhibit excellent adhesion to other layers. For example, the lower limit of the adhesion of the active material layer to the polymer layer or current collector layer in the electrode may be approximately 40gf / 20mm, 50gf / 20mm, 60gf / 20mm, 70gf / 20mm, 80gf / 20mm, 90gf / 20mm, 100gf / 20mm, 110gf / 20mm, 120gf / 20mm, 130gf / 20mm, or 140gf / 20mm, and the upper limit may be 500g. The adhesive strength may be approximately f / 20mm, 450gf / 20mm, 400gf / 20mm, 350gf / 20mm, 300gf / 20mm, 250gf / 20mm, 200gf / 20mm, 150gf / 20mm, 140gf / 20mm, 130gf / 20mm, 120gf / 20mm, 110gf / 20mm, 100gf / 20mm, 90gf / 20mm, 80gf / 20mm, or 70gf / 20mm. The adhesive strength may be within the range of being above or above any of the lower limits mentioned above, or below or below any of the upper limits mentioned above, while being within the range of being above or above any of the lower limits mentioned above.

[0170] The method for evaluating the adhesive strength is summarized in the examples.

[0171] In the above, the adhesive strength of the active material layer to the polymer layer or current collector layer means the adhesive strength in which, in the adhesive strength evaluation method described in the examples, phenomena such as the peeling of all or part of the active material layer from the polymer layer, the peeling of all or part of the polymer layer from the current collector layer, and other interfacial fracture phenomena do not occur (adhesive strength B in the evaluation method of the examples).

[0172] The present invention further relates to a method for manufacturing electrodes.

[0173] 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.

[0174] The method for forming the active material layer on the polymer layer is not particularly limited. 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 may also be applied in the present invention.

[0175] The present invention further relates to an electrode assembly or electrochemical element including the aforementioned electrodes, such as a secondary battery.

[0176] The aforementioned electrochemical element may include the electrodes as a positive electrode and / or a negative electrode. When the electrodes of the present invention 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 may be applied. [Effects of the Invention]

[0177] The present invention provides a current collector and its applications. In a steady state, the present invention provides a current collector that exhibits excellent electrical characteristics, including low resistance, and does not affect the performance and operation of a secondary battery, and in an abnormal state, can form an electrode that ensures stability by interrupting the current flow of the electrode assembly through an increase in resistance, and the present invention can provide a current collector and its applications that can ensure excellent adhesion between the layers forming the electrode. [Brief explanation of the drawing]

[0178] [Figure 1] Figure 1 is a cross-sectional view of an exemplary current collector of the present invention. [Figure 2] Figure 2 is a cross-sectional view of an exemplary electrode of the present invention. [Figure 3] Figure 3 shows the NMR analysis results for the monomer of Production Example 1. [Figure 4] Figure 4 shows the NMR analysis results for the monomers of Production Example 2. [Modes for carrying out the invention]

[0179] The content of the present invention will be specifically described through Examples and Comparative Examples below, but the scope of the present invention is not limited by the following Examples.

[0180] 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 in an NMR measurement solvent (CDCl3) at a concentration of about 10 mg / ml and used, and the chemical shift was expressed in ppm.

[0181] 2. GPC (Gel Permeation Chromatograph) The molecular weight characteristics were measured using GPC (Gel permeation chromatography). The sample was placed in a 5 mL vial and diluted with chloroform to a concentration of about 1 mg / mL. Then, the calibration standard sample and the sample to be analyzed were filtered through a syringe filter (pore size: 0.45 μm) and then measured. The analysis program used Empower3 from Waters. The elution time of the sample was compared with the calibration curve to determine the weight average molecular weight (Mw) and number average molecular weight (Mn) respectively, and the molecular weight distribution (PDI) was calculated by the ratio (Mw / Mn). The measurement conditions of GPC are as follows.

[0182] <GPC measurement conditions> Equipment: 2414 from Waters Columns: Three Styragel columns from Waters were used Solvent: THF (Tetrahydrofuran) Column temperature: 35 °C Sample concentration: 1 mg / mL, 1 μL injection Standard sample: Polystyrene (Mp: 3900000, 723000, 316500, 52200, 31400, 7200, 3940, 485)

[0183] 3. Thickness measurement The thickness of polymer layers and other components was measured by cross-sectional processing using an ion milling device (Hitachi, IM5000) followed by acquisition of SEM (Scanning Electron Microscope) (JEOL, JSM-7200F) images.

[0184] The cross-section formation conditions for the ion milling were as follows: the device was set to cross-section milling mode, with a speed (reciprocation / min) of 3, an acceleration voltage of 6.0kV, a discharge voltage of 15kV, a current of 150μA, and a time of 4 hours.

[0185] 4. Method for measuring oxidation potential The oxidation potential was measured using the following method. A polymer layer approximately 10 μm thick was formed on aluminum foil (Al Foil) with a thickness of approximately 15 μm using a conductive copolymer. The polymer layer was formed using the same method as described in each example or comparative example, with 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). As the separation membrane, the WL20C model from Double Uscope Korea was used, as the lithium film, a lithium film with a thickness of approximately 100 μm was used, and as the electrolyte, a product from Enchem (1M LiPF6 solution (solvent: EC / DMC / EMC = 3 / 4 / 3 (mass ratio), EC: ethylene carbonate, DMC: dimethyl carbonate, EMC: ethyl methyl carbonate)) was used.

[0186] 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.

[0187] 5.DC resistance measurement method DC resistance was evaluated using the same coin cell used in oxidation potential measurement. A voltage of 4.3 eV was applied to the coin cell at room temperature (25°C) for 10 minutes, and the DC resistance was measured using a Fluke digital multimeter (FLUKE-87-5).

[0188] 6. AC Impedance Resistance The AC impedance resistance was evaluated by EIS (Electrochemical Impedance Spectronization) using the same coin cell used for oxidation potential measurement. 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 using the EIS measurement method at 50,000Hz to 0.1Hz. The AC impedance resistance obtained in the high frequency region was measured. An electrochemical measuring instrument (Pontentiostat) (Princeton Applied Research, PARASTAT-MC) was used for the EIS measurement.

[0189] 7. Measurement of maximum resistance change rate (DC resistance) The maximum resistance change rate △R1 is determined by the following equation 1.

[0190] <Expression 1> △R1=Max{(R n+5 / R n ) / 5}

[0191] In Equation 1, R nR is the DC resistance at any temperature n°C within the range of 25°C to 135°C. n+5 This is the DC resistance at a temperature 5°C higher than the aforementioned temperature n°C ((n+5)°C).

[0192] The aforementioned △R1 ​​is measured by the following method.

[0193] A coin cell for DC resistance measurement is placed in the center of a convection oven (JOTECH, OF3-05W), and the oven temperature is set to an initial temperature of 25°C and a final temperature of 135°C, with the temperature rising by 5°C per minute. To enable resistance measurement, a multimeter for resistance measurement (Fluke digital multimeter (FLUKE-87-5)) is connected to the coin cell outside the oven. Next, the DC resistance is measured at each temperature (25°C, 30°C, 35°C, 40°C, and so on, increasing the measurement temperature by 5°C up to 135°C) as the temperature rises as set. The R of Equation 1 is calculated for each measurement temperature. n and R n+5 Each was measured, and R n+5 / R n (R 30 / R 25 , R 35 / R 30 ~R 135 / R 130 After calculating ( ), divide this by 5 again.

[0194] In the temperature range of 25℃ to 135℃, the above (R n+5 / R n After calculating ) / 5, the maximum value of ΔR1 is determined. Through ΔR1, the temperature reactivity of the resistance increase of the conductive copolymer (polymer layer) at the on-set temperature can be confirmed.

[0195] The aforementioned On-Set temperature is (R n+5 / R n ) / 5 is the temperature n°C at which the maximum value is observed.

[0196] The same coin cell used for measuring DC resistance was the same one used for measuring oxidation potential.

[0197] 8. Measurement of maximum resistance change rate (AC impedance) The maximum resistance change rate ΔR2 is determined by the following equation 2.

[0198] <Expression 2> △R² = Max{(R z+5 / R z ) / 5}

[0199] In Equation 2, R z R is the AC impedance resistance at any temperature z°C within the range of 25°C to 135°C. z+5 This is the AC impedance resistance at a temperature 5°C higher than the aforementioned temperature z°C ((z+5)°C).

[0200] The aforementioned △R2 is measured by the following method.

[0201] A coin cell for measuring AC impedance resistance is placed in the center of a convection oven (JOTECH, OF3-05W), and the oven temperature is set to an initial temperature of 25°C and a final temperature of 135°C, with the temperature rising by 5°C per minute. To enable resistance measurement, the coin cell is connected to an external resistance meter (potentiostat) (Princeton Applied Research, PARASTAT-MC) outside the oven. Next, the AC impedance resistance is measured at each temperature (increasing the measurement temperature by 5°C in the order of 25°C, 30°C, 35°C, 40°C, up to 135°C) as the temperature rises as set. R in Equation 2 is calculated for each measurement temperature. z and R z+5 Each was measured, and R z+5 / R z (R 30 / R 25 , R 35 / R 30 ~R 135 / R 130 After calculating ( ), divide this by 5 again.

[0202] In the temperature range of 25℃ to 135℃, the above (Rz +5 After calculating (Rz) / 5, find the maximum value of it, which is △R2.

[0203] The temperature reactivity of the resistance increase of the conductive copolymer (polymer layer) at the on-set temperature can be confirmed via the aforementioned ΔR2.

[0204] The aforementioned On-Set temperature is (R z+5 / R z ) / 5 is the temperature n°C at which the maximum value is observed.

[0205] The same coin cell used for measurement was the same one used during oxidation potential measurement.

[0206] The AC impedance resistor was determined by applying a voltage of 4.3V for 10 minutes, obtaining a Nyquist plot using the EIS measurement method at 50,000Hz to 0.1Hz, and taking the resistance from the semicircle in the high-frequency region.

[0207] 9. Discharge Capacity Measurement The discharge capacity to verify the result of Equation 3 below was evaluated using the following method.

[0208] <Expression 3> △R3 = 100 × (C 1- C2) / C1

[0209] In Equation 3, ΔR3 is the percentage change in discharge capacity, C1 is the discharge capacity at room temperature (approximately 25°C), and C2 is the discharge capacity after storage at 70°C for 60 hours.

[0210] A coin cell (reference capacity: 200 mAh / g) for verifying the discharge capacity of Equation 3 was prepared using a CR2032 standard coin cell kit (Welcos CR2032 coin cell kit). The electrode prepared in the example or comparative example was used as the positive electrode, and a lithium film (thickness: 100 μm) was used as the negative electrode. As the electrolyte, a carbonate-based electrolyte, specifically a 1 M LiPF6 solution (solvent: EC / DMC / EMC = 3 / 4 / 3 (mass ratio), EC: ethylene carbonate, DMC: dimethyl carbonate, EMC: ethyl methyl carbonate) was used, and as the separation membrane, a PE (poly(ethylene)) separation membrane (WL20C model from Double UScope Korea) was used.

[0211] The coin cell was subjected to one charge / discharge cycle at 25°C, and the capacity at 0.2C was used as the discharge capacity in Equation 3. One charge / discharge cycle means that the charging termination voltage was set to 4.5V and the charging termination current to 1mA, and the CC (Constant Current) / CV (Constant Voltage) method was used for charging, and the discharging termination voltage was set to 3.0V, and the discharging method was used at 0.2C for discharging, and this process was repeated once as one cycle. The discharge capacity after one charge / discharge cycle was applied to the discharge capacity (C1, C2) in Equation 3.

[0212] Immediately after the fabrication of the coin cell, C1 was determined by applying the measurement method described above. Then, after storing the coin cell at 70°C for 60 hours, C2 was determined by applying the measurement method described above.

[0213] 10. Discharge Capacity Measurement The discharge capacity to verify the result of Equation 4 below was evaluated using the following method.

[0214] <Expression 4> △R4 = 100 × (C 1- C3) / C1

[0215] In Equation 4, ΔR4 is the percentage change in discharge capacity, C1 is the discharge capacity at room temperature (approximately 25°C), and C3 is the discharge capacity after storage at 70°C for 60 hours, followed by storage at 130°C for 10 minutes.

[0216] The coin cell used to verify the discharge capacity of Equation 4 was fabricated using the same method as the coin cell used to verify Equation 3, and the discharge capacity was measured in the same manner.

[0217] In other words, immediately after the coin cell is manufactured, C1 is determined by applying the measurement method to verify the above equation 3.

[0218] Subsequently, the coin cell was stored at 70°C for 60 hours, then again at 130°C for 10 minutes, after which C3 was determined.

[0219] C3 was determined using the following method: The charging termination voltage was set to 4.5V and the charging termination current to 1mA, and the battery was charged at a rate of 0.5C using the CC (Constant Current) / CV (Constant Voltage) method. Then, the discharge termination voltage was set to 3.0V, and the battery was discharged again at a rate of 2C using the CC (Constant Current) method. This process constituted one cycle, and the above cycle was repeated 30 times. The discharge capacity after 30 charge-discharge cycles was applied to C3 in Equation 4. The 30 charge-discharge cycles were performed at 45°C.

[0220] 11. Method for evaluating adhesive strength The adhesive strength was measured using a TA analyzer (model name: TAXTplusC) according to a known method for measuring the adhesive strength of the active material layer. The test specimens were cut to a width of approximately 20 mm and the adhesive strength was evaluated. As test specimens, the following examples or comparative examples were evaluated for laminates in which a polymer layer was formed on the current collector body (adhesion strength A) and for final electrodes in which an active material layer was formed on the polymer layer (adhesion strength B). That is, adhesive strength A is the adhesive strength of the polymer layer to the current collector body, and adhesive strength B is the adhesive strength of the active material layer to the polymer layer or the current collector body. During adhesive strength measurement, the peeling angle was set to 90 degrees and the peeling speed to approximately 5 mm / sec. After measurement, the portion where the peak stabilized was averaged and defined as the adhesive strength.

[0221] Manufacturing Example 1. Synthesis of monomer (A) The monomer of compound A below was synthesized by the following method.

[0222] [ka]

[0223] In chemical formula A, R1 and R2 are linear butyl groups.

[0224] 6 g (41.61 mmol, 1 eq) of 3,4-dimethoxythiophene and 10.187 g (54.10 mmol, 1.3 eq) of 2,2-dibutyl-1,3-propanediol were dissolved in 200 ml of toluene with 500 mg of p-toluenesulfonic acid (p-TsOH) and mixed. The mixture was transetherified under reflux at 120°C, and methanol produced by the reaction was removed using a 4A molecular sieve packed in a soxhlet extractor. After refluxing for 24 hours, the reaction product was 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 methylene chloride / hexane (1:4) elution column chromatography to obtain compound 1 (3,4-(3,3'-dibutylpropylenedioxy)thiophene). The NMR analysis results for the target compound (monomer (A)) are shown in Figure 3.

[0225] Manufacturing Example 2. Synthesis of Monomer (B) The monomer in the following compound B was synthesized by the following method.

[0226] [ka]

[0227] 1.372 g (12.02 mmol, 1 eq) of 3-methoxythiophene and 3 g (16.83 mmol, 1.4 eq) of triethylene glycol monomethyl ether were dissolved in 100 ml of toluene with 230 mg of p-toluenesulfonic acid (p-TsOH) and mixed. The mixture was refluxed at 120°C, and methanol produced by the reaction (transetherification) was removed using a 4A molecular sieve packed in a soxhlet extractor. After refluxing the reaction product for 24 hours, it was 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 (B)). The NMR analysis results for the target compound (monomer (B)) are shown in Figure 4.

[0228] Example 1. Synthesis of polythiophene (A) Polythiophene (A) was produced by dissolving 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride in 150 ml of methylene chloride, then adding 1.58 g (5.91 mmol, 0.9 eq) of monomer (A) from Production Example 1 and 0.16 g (0.66 mmol, 0.1 eq) of monomer (B) from Production Example 2, and polymerizing at 25°C for 24 hours.

[0229] 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, monomer (A), monomer (B), 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).

[0230] Polythiophene (A) had a weight-average molecular weight (Mw) of 60,200 g / mol and a number-average molecular weight (Mn) of 18,500 g / mol, respectively, and an oxidation potential of approximately 3.5 V.

[0231] Furthermore, the EP value of polythiophene (A) according to formula A is approximately 28,030.

[0232] Electrode manufacturing An Al foil with a thickness of approximately 15 μm was used as the current collector body. The manufactured polythiophene (A) was dispersed in a solvent (Chloroform) at a concentration of approximately 2.0% by weight to produce a coating solution. The coating solution was coated onto the current collector body using a bar coating method, and dried and annealed at 130°C for about 1 hour to form a polymer layer with a thickness of approximately 300 nm. Next, 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 (polyvinylidene 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, it was further dried under vacuum conditions at 120°C. Next, electrodes were manufactured by rolling the material to a porosity of approximately 25%.

[0233] Example 2. The electrode was manufactured in the same manner as in Example 1, except that the polymer layer was formed to a thickness of approximately 500 nm.

[0234] Example 3. Synthesis of polythiophene (C) A solution prepared by dissolving 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride in 150 ml of methylene chloride was charged with 1.41 g (5.26 mmol, 0.8 eq) of monomer (A) and 0.35 g (1.32 mmol, 0.2 eq) of monomer (B) of Production Example 1, and polymerization was carried out at 25 °C for 24 hours to produce polythiophene (C). The weight ratio (A:B) of monomer (A) units to monomer (B) units in 1 produced with polythiophene (C) is about 4:1.

[0235] After putting the polymerization solution into a permeation membrane with a MWCO (molecular weight of cut-off) of 5000, it was immersed in 200 ml of an acetonitrile solvent to remove unreacted iron(III) chloride and monomers. The residue deposited inside the permeation membrane was washed with methanol and dried at 60 °C for 12 hours to produce polythiophene (C).

[0236] For polythiophene (C), the weight average molecular weight (Mw) and the number average molecular weight (Mn) were 48,300 g / mol and 11,200 g / mol, respectively, and the oxidation potential was about 3.55 V.

[0237] Also, the EP value according to the formula A in the polythiophene (C) is about 8,485.

[0238] Electrode manufacturing The electrode was manufactured in the same manner as in Example 1, and at this time, the thickness of the polymer layer was about 300 nm.

[0239] Example 4. Synthesis of polythiophene (B) A solution prepared by dissolving 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride in 150 ml of methylene chloride was charged with 1.16 g (5.9 mmol, 0.9 eq) of 3-octylthiophene and 0.16 g (0.66 mmol, 0.1 eq) of the monomer (B) of Production Example 2, and polymerization was carried out at 25°C for 24 hours to produce polythiophene (B). The weight ratio (3-OT:B) of the 3-octylthiophene unit (3-OT) produced with polythiophene (B) and the unit of the monomer (B) of Production Example 2 was approximately 7:1.

[0240] After putting the polymerization solution into a dialysis membrane with an MWCO (molecular weight of cut-off) of 5000, it was immersed in 200 ml of an acetonitrile solvent to remove unreacted iron(III) chloride and the monomer. The residue deposited inside the dialysis membrane was washed with methanol and dried at 60°C for 12 hours to produce polythiophene (B).

[0241] The weight average molecular weight (Mw) and number average molecular weight (Mn) of polythiophene (B) were 56,500 g / mol and 12,800 g / mol, respectively, and the oxidation potential was about 3.7 V.

[0242] Also, the EP value according to the formula A in the polythiophene (B) was about 19,394.

[0243] Electrode manufacturing The electrode was manufactured in the same manner as in Example 1, and at this time, the thickness of the polymer layer was about 300 nm.

[0244] Example 5. Synthesis of polythiophene (D) Polythiophene (D) was prepared by dissolving 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride in 150 ml of methylene chloride, then adding 1.03 g (5.24 mmol, 0.8 eq) of 3-octylthiophene and 0.32 g (1.32 mmol, 0.2 eq) of monomer (B). Polymerization was carried out at 25°C for 24 hours. In polythiophene (D), the weight ratio of 3-octylthiophene units (3-OT) to monomer (B) (3-OT:B) was approximately 3:1.

[0245] 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 and monomers. The residue precipitated inside the permeable membrane was washed with methanol and dried at 60°C for 12 hours to produce polythiophene (D).

[0246] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polythiophene (D) were 45,700 g / mol and 10,300 g / mol, respectively, and the oxidation potential was approximately 3.7 V.

[0247] Furthermore, the EP value of polythiophene (D) according to formula A is approximately 7,803.

[0248] Electrode manufacturing The electrodes were manufactured using the same method as in Example 1, with the polymer layer thickness set to approximately 500 nm.

[0249] Example 6. The electrodes were manufactured using the same method as in Example 1. In Example 6, when forming the polymer layer, the coating solution was coated onto the current collector body using a bar coating method and dried at 90°C for about 20 minutes to form the layer.

[0250] Comparative Example 1. The electrodes were manufactured in the same manner as in Example 1, except that a polymer layer was not formed.

[0251] Comparative Example 2. Synthesis of polythiophene (F) A solution of 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride in 150 ml of methylene chloride was charged with 3-octylthiophene (6.56 mmol, 1.29 eq), and polymerization was carried out at 25 °C for 24 hours to produce polythiophene (F).

[0252] The polymerization solution was placed in a dialysis membrane with a MWCO (molecular weight of cut-off) of 5000 and immersed in 200 ml of acetonitrile solvent to remove unreacted iron(III) chloride and the monomer. The residue deposited inside the dialysis membrane was washed with methanol and dried at 60 °C for 12 hours to produce polythiophene (F).

[0253] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polythiophene (F) were 59,200 g / mol and 17,400 g / mol, respectively, and the oxidation potential was about 3.7 V.

[0254] Electrode manufacturing The electrodes were fabricated in the same manner as in Example 1, and at this time, the thickness of the polymer layer was about 300 nm.

[0255] The measurement results for the fabricated electrodes are summarized as shown in Tables 1 and 2 below. In Tables 1 and 2 below, C1 in Formula 3 and C1 in Formula 4 should theoretically show the same numerical value, but some differences occurred within the error range during actual experiments.

[0256]

Table 1

[0257]

Table 2

[0258] Tables 1 and 2 show that, in the case of electrodes according to the present invention, under steady-state conditions, they exhibit low resistance and do not affect the performance and operation of the secondary battery. Under abnormal conditions such as overcharging, high-temperature exposure, or external shock, they exhibit the characteristic of ensuring stability by interrupting the current flow to the electrode assembly through an increase in resistance. Furthermore, in the examples, excellent adhesive strength was also ensured.

[0259] Furthermore, a comparison of Examples 1 and 6 confirms that even when using the same type of conductive copolymer, differences in effectiveness can occur due to changes in crystallinity caused by annealing conditions.

[0260] In Comparative Example 1, which lacked a polymer layer, no increase in resistance occurred even under high-temperature conditions. In Comparative Example 2, an increase in resistance occurred under high-temperature conditions, but the on-set temperature was low, and the increase in resistance was also observed during storage under high-temperature conditions, negatively impacting the battery's performance.

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 copolymer, The adhesive strength of the polymer layer to the current collector body is 20 gf / 20 mm or more. A current collector having a DC resistance of 10,000 Ω·cm or less at 25°C, or an AC impedance resistance of 1,000 Ω or less.

2. Current collector body, and The current collector body includes a polymer layer formed on one or both sides, The polymer layer comprises a conductive copolymer having polar functional groups. The polar functional group includes a carboxyl group, a hydroxyl group, an amino group, a cyano group, a nitro group, an ether group, or the functional group shown in the following formula 3, in the current collector. 【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.

3. The current collector according to claim 2, wherein the conductive copolymer has an EP value in the range of 6,000 to 20,000 according to the following formula A. [Formula A] EP = Mn / P In formula A, Mn is the number-average molecular weight of the conductive copolymer, and P is the number of moles of monomer units containing the polar functional group in the conductive copolymer.

4. The current collector according to claim 1 or 2, wherein the number-average molecular weight of the conductive copolymer is in the range of 5,000 to 100,000 g / mol.

5. The current collector according to claim 2, wherein the DC resistance at 25°C is 10,000 Ω·cm or less.

6. The current collector according to claim 2, wherein the AC impedance resistance is 1,000 Ω or less.

7. The current collector according to claim 1 or 2, wherein ΔR1 in the following formula 1 is 100 Ω·cm / ℃ or more. [Formula 1] △R1=Max{(R ｎ＋５ / R ｎ ) / 5} In Formula 1, R ｎ is the DC resistance at an arbitrary temperature n°C within the range of 25°C to 135°C, and R ｎ＋５ is the DC resistance at a temperature ((n + 5)°C) that is 5°C higher than the temperature n°C. Max{(R ｎ＋５ / R ｎ ) / 5} is the maximum value among the (R n+5 / R ｎ ) / 5 values confirmed within the temperature range of 25°C to 135°C.

8. △R1 is confirmed R ｎ The current collector according to claim 7, wherein the temperature exceeds 80°C.

9. The current collector according to claim 1 or 2, wherein ΔR2 in the following formula 2 is 10 Ω / °C or more. [Formula 2] △R2=Max{(R ｚ＋５ / R ｚ ) / 5} In Equation 2, R ｚ R is the AC impedance resistance at any temperature n°C within the range of 25°C to 135°C. ｚ＋５ This is the AC impedance resistance at a temperature 5°C higher than the aforementioned temperature n°C ((n+5)°C), and Max { (R ｚ＋５ / R ｚ ) / 5} was confirmed within the temperature range of 25°C to 135°C (R ｚ＋５ / R ｚ ) / This is the maximum value among the five values.

10. △R2 is confirmed R ｚ The current collector according to claim 9, wherein the temperature is 80°C or higher.

11. The current collector according to claim 2, wherein the conductive copolymer further comprises long-chain hydrocarbon functional groups.

12. The current collector according to claim 11, wherein the ratio (M1 / M2) of the number of moles of long-chain hydrocarbon functional groups (M1) to the number of moles of polar functional groups (M2) in the conductive copolymer is in the range of 1.5 to 20.

13. The current collector according to claim 1 or 2, wherein the conductive copolymer comprises monomer units as shown in Chemical Formula 1 below. 【Chemistry 2】 In chemical formula 1, R １ and R ２ Each of these is independently a hydrogen atom, a polar functional group, or a long-chain hydrocarbon functional group, but R １ and R ２ At least one of them is a polar functional group or a long-chain hydrocarbon functional group, or R １ and R ２ These are linked together to form the divalent functional group shown in formula 2 below. 【Transformation 3】 In chemical formula 2, L １ and L ２ Each of these is independently a single bond, an alkylene group, or an alkylidene group, and R ３ and R ４ Each of these is independently a hydrogen atom, a polar functional group, or a long-chain hydrocarbon functional group, but R ３ and R ４ At least one of them is a polar functional group or a long-chain hydrocarbon functional group.

14. The current collector according to claim 1 or 2, wherein the conductive copolymer comprises monomer units of chemical formula 4 and monomer units of chemical formula 5. 【Chemistry 4】 In chemical formula 4, R ６ and R ７ Each is independently a hydrogen atom or a long-chain hydrocarbon functional group, but R ６ and R ７ At least one of them is a long-chain hydrocarbon functional group, or R ６ and R ７ These are linked together to form the divalent functional group shown in formula 6 below. 【Transformation 5】 In chemical formula 5, R ８ and R ９ Each is independently a hydrogen atom or a polar functional group, but R ８ and R ９ At least one of them is a polar functional group, or R ８ and R ９ These are linked together to form the divalent functional group shown in formula 7 below. 【Transformation 6】 In chemical formula 6, L ５ and L ６ Each of these is independently a single bond, an alkylene group, or an alkylidene group, and R １０ and R １１ Each is independently a hydrogen atom or a long-chain hydrocarbon functional group, but R １０ and R １１ At least one of them is a long-chain hydrocarbon functional group. 【Transformation 7】 In chemical formula 7, L ７ and L ８ Each of these is independently a single bond, an alkylene group, or an alkylidene group, and R １２ and R １３ Each is independently either a hydrogen atom or a polar functional group, or R １２ and R １３ At least one of them is a polar functional group.

15. A current collector according to claim 1 or 2, and An electrode comprising an active material layer formed on the polymer layer of the current collector.

16. The electrode according to claim 15, wherein the adhesive strength of the active material layer to the polymer layer or current collector layer is 40 gf / 20 mm or more.

17. An electrode assembly comprising the electrode described in claim 15.

18. A secondary battery comprising the electrode assembly described in claim 17.

Images