Electrode

Abstract

The present application relates to electrodes and their uses. The present application provides an electrode and its uses that, under normal and storage conditions, exhibit low resistance so as not to affect the performance and operation of a secondary battery, and, under abnormal conditions caused by overcharging, exposure to high temperatures, or external shock, block current flow in the electrode assembly through an increase in resistance to ensure stability. The present application provides an electrode and its uses that can variably control the movement of charge according to the internal temperature of a secondary battery.

Description

Technology Field

[0001] This application relates to an electrode. Background Technology

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

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

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

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

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

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

[0008] The present application relates to electrodes and their uses. The purpose of the present application is to provide an electrode and its uses that can ensure stability by exhibiting low resistance in normal and storage conditions so as not to affect the performance and operation of a secondary battery, and by blocking the current flow of the electrode assembly through an increase in resistance in abnormal conditions caused by overcharging, exposure to high temperatures, or external shock. The purpose of the present application is to provide an electrode and its uses that can variably control the movement of charge according to the internal temperature of a secondary battery. means of solving the problem

[0009] In this specification, the term "room temperature" means a natural temperature that has not been heated or cooled, and may be, for example, any temperature within the range of 10°C to 30°C or a temperature of about 23°C or about 25°C or about 27°C.

[0010] In cases where the measurement temperature affects the physical properties mentioned in this specification, unless otherwise specifically defined, said physical property is the property measured at room temperature.

[0011] Unless otherwise specifically defined, the unit of temperature in this specification is Celsius (°C).

[0012] In this specification, the term atmospheric pressure refers to natural pressure that has not been pressurized or depressurized, and may typically refer to a pressure of about 730 mmHg to 790 mmHg.

[0013] In cases where the measured pressure affects the physical properties mentioned in this specification, unless specifically otherwise defined, said physical property is the property measured at atmospheric pressure.

[0014] This application relates to an electrode.

[0015] The electrode of the present application may include a current collector layer, an active material layer formed on the current collector layer, and an intermediate layer between the current collector layer and the active material layer. FIG. 1 is a drawing showing the case where the current collector layer (100), the intermediate layer (200), and the active material layer (300) are formed sequentially.

[0016] As shown in the drawing, the current collector layer (100), the intermediate layer (200), and the active material layer (300) may be in contact with each other, or other elements may exist between them. Additionally, although the drawing shows a case where the active material layer (300) exists only on one side of the current collector layer (100), the active material layer (300) may exist on both sides of the current collector layer (100). In this case, the intermediate layer (200) may exist as two layers between each of the active material layer (300) on both sides of the current collector layer (100) and the current collector layer (100), or as one layer between either of the active material layer (300) on both sides and the current collector layer (100).

[0017] The electrode of the present application may be an anode or a cathode applied to a secondary battery.

[0018] In the electrode of the present application, the intermediate layer is a layer capable of variably controlling the movement of charge through the electrode according to temperature.

[0019] By applying the above intermediate layer, the electrode of the present application exhibits low resistance in a normal state (charging or discharging state) and storage state, and in an abnormal state caused by overcharging, exposure to high temperature, or external shock, the resistance increases, thereby blocking the current flow of the electrode assembly and ensuring stability.

[0020] In one example, the intermediate layer or electrode has a DC resistance of 10 at 25°C. 4 It may be less than Ω·cm. The above DC resistance is 9500 Ω·cm or less, 9000 Ω·cm or less, 8500 Ω·cm or less, 8000 Ω·cm or less, 7500 Ω·cm or less, 7000 Ω·cm or less, 6500 Ω·cm or less, 6000 Ω·cm or less, 5500 Ω·cm or less, 5000 Ω·cm or less, 4500 Ω·cm or less, 4000 Ω·cm or less, 3500 Ω·cm or less, 3000 Ω·cm or less, 2500 Ω·cm or less, 2000 Ω·cm or less, 1500 Ω·cm or less, 1000 Ω·cm or less, 950 Ω·cm or less, 900 Ω·cm or less, 850 Ω·cm or less, 800 Ω·cm or less, The DC resistance may be 750 Ω·cm or less, 700 Ω·cm or less, 650 Ω·cm or less, 600 Ω·cm or less, 550 Ω·cm or less, 500 Ω·cm or less, 450 Ω·cm or less, 400 Ω·cm or less, or 350 Ω·cm or less. The above DC resistance may be 10 Ω·cm or more, 50 Ω·cm or more, 100 Ω·cm or more, 150 Ω·cm or more, 200 Ω·cm or more, 250 Ω·cm or more, 300 Ω·cm or more, 350 Ω·cm or more, 400 Ω·cm or more, 450 Ω·cm or more, 500 Ω·cm or more, 550 Ω·cm or more, or 600 Ω·cm or more. The above DC resistance may have a range between any upper limit among the upper limits described above and any lower limit among the lower limits described above. The above DC resistance is measured in the manner described in the embodiments of this specification.

[0021] The above intermediate layer or electrode has an AC impedance resistance of 10 3The AC impedance resistance may be Ω or less. In other examples, the above AC impedance resistance may be 950 Ω or less, 900 Ω or less, 850 Ω or less, 800 Ω or less, 750 Ω or less, 700 Ω or less, 650 Ω or less, 600 Ω or less, 550 Ω or less, 500 Ω or less, 450 Ω or less, 400 Ω or less, 350 Ω or less, 300 Ω or less, 250 Ω or less, 200 Ω or less, 150 Ω or less, 100 Ω or less, 95 Ω or less, 90 Ω or less, 85 Ω or less, 80 Ω or less, 75 Ω or less, 70 Ω or less, 65 Ω or less, 60 Ω or less, 55 Ω or less, or 50 Ω or less. The above AC impedance resistance may be 10 Ω or more, 15 Ω or more, 20 Ω or more, 25 Ω or more, 30 Ω or more, 35 Ω or more, 40 Ω or more, 450 Ω or more, 50 Ω or more, 55 Ω or more, 60 Ω or more, 65 Ω or more, 70 Ω or more, 75 Ω or more, 80 Ω or more, or 85 Ω or more. The above AC impedance resistance may have a range between any upper limit among the upper limits described above and any lower limit among the lower limits described above. The above AC impedance resistance is measured in the manner described in the embodiments of this specification.

[0022] By the fact that the electrode or intermediate layer of the present application exhibits the DC resistance and / or AC impedance resistance, the secondary battery or electrode assembly to which the electrode is applied can be stably operated or stored in a normal state (charging or discharging state) and a storage state.

[0023] The electrode of the present application to which the above intermediate layer is applied has its resistance increased under abnormal high-temperature conditions caused by overcharging, exposure to high temperature, or external shock, and thereby can ensure stability by blocking the current flow of the electrode assembly.

[0024] For example, the electrode or intermediate layer may be configured to exhibit a characteristic such that △R1 of Formula 1 below is 100 Ω·cm / ℃ or higher.

[0025] [Equation 1]

[0026] △R1 = Max{(R n+5 / R n ) / 5}

[0027] R in Equation 1 n is a DC resistance at any temperature n℃ within the range of 25℃ to 135℃, and R n+5 is the DC resistance at a temperature 5℃ higher ((n+5)℃) than the above temperature n℃, and Max{(R n+5 / R n ) / 5} is (R confirmed within a temperature range of 25℃ to 135℃ n+5 / R n It is the maximum value among ) / 5 values.

[0028] The method for measuring △R1 of Equation 1 is described in the examples. In the method for verifying △R1, the initial temperature is 25°C and the final temperature is 135°C. By increasing the temperature by 5°C increments from the initial temperature of 25°C and measuring the DC resistance at each temperature, the R n+5 and R n Check. For example, in the case where n is 90, R 95 / R 90 ...is the ratio of the DC resistance at 95°C to the DC resistance at 90°C. The fact that △R1 is 100 Ω·cm / °C or more at any temperature within the temperature range of 25°C to 135°C means that the resistance of the intermediate layer or electrode rises relatively rapidly at any temperature within the above temperature range.

[0029] The above △R1 is 100Ω·cm / ℃ or higher, 150Ω·cm / ℃ or higher, 200Ω·cm / ℃ or higher, 250Ω·cm / ℃ or higher, 300Ω·cm / ℃ or higher, 350Ω·cm / ℃ or higher, or 400Ω·cm / ℃, or 1,000Ω·cm / ℃ or lower, 950Ω·cm / ℃ or lower, 900Ω·cm / ℃ or lower, 850Ω·cm / ℃ or lower, 800Ω·cm / ℃ or lower, 750Ω·cm / ℃ or lower, 700Ω·cm / ℃ or lower, 650Ω·cm / ℃ or lower, 600Ω·cm / ℃ or lower, 550Ω·cm / ℃ or lower, 500Ω·cm / ℃ or lower, 450Ω·cm / ℃ or lower, 400Ω·cm / ℃ or lower, 350 It may be Ω·cm / ℃ or less, 300 Ω·cm / ℃ or less, or 250 Ω·cm / ℃ or less. The range of △R1 may be within the range of any one of the upper limits mentioned above and any one of the lower limits mentioned above.

[0030] By securing the above characteristics, the electrode of the present application can ensure stability by increasing resistance under abnormal high-temperature conditions caused by overcharging, exposure to high temperatures, or external shocks, thereby blocking the current flow of the electrode assembly.

[0031] Meanwhile, the temperature at which △R1 of 100Ω·cm / ℃ or higher is confirmed, i.e., R nThe temperature at may exceed 80°C. In other examples, the above temperature may be 80°C or higher, 81°C or higher, 82°C or higher, 83°C or higher, 84°C or higher, 85°C or higher, 86°C or higher, 87°C or higher, 88°C or higher, 89°C or higher, 90°C or higher, 91°C or higher, 92°C or higher, 93°C or higher, 94°C or higher, or 95°C or higher. The above temperature may be 200°C or lower, 190°C or lower, 180°C or lower, 170°C or lower, 160°C or lower, 150°C or lower, 140°C or lower, 130°C or lower, 120°C or lower, 110°C or lower, 100°C or lower, or 90°C or lower. The above temperature range may be within the range of any one of the aforementioned upper limits and any one of the aforementioned lower limits. By designing the electrode so that the above temperature exceeds 80℃, stability can be ensured under abnormal conditions while maintaining the performance of the electrode, electrode assembly, or secondary battery even when storage of the electrode, electrode assembly, or secondary battery is performed at a relatively high temperature.

[0032] The above electrode or intermediate layer can be configured to exhibit a characteristic in which △R2 of Formula 2 below is 10Ω / ℃ or higher.

[0033] [Equation 2]

[0034] △R2 = Max{(R z+5 / R z ) / 5}

[0035] R in Equation 2 z is an AC impedance resistance at any temperature n℃ within the range of 25℃ to 135℃, and R z+5 is the AC impedance resistance at a temperature 5°C higher than the above temperature n°C ((n+5)°C), and Max{(R z+5 / R z ) / 5} is (R confirmed within a temperature range of 25℃ to 135℃ z+5 / R z It is the maximum value among ) / 5 values.

[0036] The method for measuring △R2 of Equation 2 above is described in the examples. In the method for verifying △R2, the initial temperature is 25℃ and the final temperature is 135℃. By increasing the temperature by 5℃ increments from the initial temperature of 25℃ and measuring the AC impedance resistance at each temperature, the R z+5 and R z Check . For example, in the case where n is 90, R 95 / R 90 ΔR2 is the ratio of the AC impedance resistance at 95°C to the AC impedance resistance at 90°C. The fact that ΔR2 is 10 Ω / °C or more at any temperature within the temperature range of 25°C to 135°C means that the resistance of the intermediate layer or electrode rises relatively sharply at any temperature within the above temperature range.

[0037] The above △R2 is 12Ω / ℃ or higher, 14Ω / ℃ or higher, 16Ω / ℃ or higher, 18Ω / ℃ or higher, 20Ω / ℃ or higher, 22Ω / ℃ or higher, 24Ω / ℃ or higher, 26Ω / ℃ or higher, 28Ω / ℃ or higher, 30Ω / ℃ or higher, or 33Ω / ℃, or 100Ω / ℃ or lower, 95Ω / ℃ or lower, 90Ω / ℃ or lower, 85Ω / ℃ or lower, 80Ω / ℃ or lower, 75Ω / ℃ or lower, 70Ω / ℃ or lower, 65Ω / ℃ or lower, 60Ω / ℃ or lower, 55Ω / ℃ or lower, 50Ω / ℃ or lower, 45Ω / ℃ or lower, 40Ω / ℃ or lower, 35Ω / ℃ or lower, 30Ω / ℃ or lower, or approximately 25Ω / ℃ or lower. It may be possible. The range of the above △R2 may be within the range of any one of the upper limits mentioned above and any one of the lower limits mentioned above.

[0038] By securing the above characteristics, the electrode of the present application can increase its resistance under abnormal high-temperature conditions caused by overcharging, exposure to high temperatures, or external shocks, thereby blocking the current flow of the electrode assembly and ensuring stability.

[0039] The temperature at which △R2 of 10Ω / ℃ or higher is confirmed, i.e., R z The temperature at may exceed 80°C. In other examples, the above temperature may be 80°C or higher, 81°C or higher, 82°C or higher, 83°C or higher, 84°C or higher, 85°C or higher, 86°C or higher, 87°C or higher, 88°C or higher, 89°C or higher, 90°C or higher, 91°C or higher, 92°C or higher, 93°C or higher, 94°C or higher, or 95°C or higher. The above temperature may be 200°C or lower, 190°C or lower, 180°C or lower, 170°C or lower, 160°C or lower, 150°C or lower, 140°C or lower, 130°C or lower, 120°C or lower, 110°C or lower, 100°C or lower, or 90°C or lower. The above temperature range may be within the range of any one of the aforementioned upper limits and any one of the aforementioned lower limits. By designing the electrode so that the above temperature exceeds 80℃, stability can be ensured under abnormal conditions while maintaining the performance of the electrode, electrode assembly, or secondary battery even when storage of the electrode, electrode assembly, or secondary battery is performed at a relatively high temperature.

[0040] The above intermediate layer or electrode can be configured to exhibit a characteristic in which the absolute value of △R3 of Equation 3 below is less than 10%.

[0041] [Equation 3]

[0042] △R3 = 100 × (C1-C2) / C1

[0043] In Equation 3, C1 is the discharge capacity at room temperature (about 25°C), and C2 is the discharge capacity after storage at 70°C for 60 hours.

[0044] C1 and C2 in Equation 3 are discharge capacities measured for a coin cell to which the electrodes are applied, and the specific method of measuring them is summarized in the examples.

[0045] The absolute value of △R3 in Equation 3 may be less than 10%, 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7% or less, 6.5% or less, 6% or less, 5.5% or less, 5% or less, 4.5% or less, 4% or less, 3.5% or less, 3% or less, 2.5% or less, 2% or less, 1.5% or less, 1% or less, or approximately 0.5% or less. In other examples, the above absolute value may be 0% or more, 0.5% or more, or 1.5% or more. The range of the above absolute value may be within the range of any one of the aforementioned upper limits and any one of the aforementioned lower limits. By designing the electrode to ensure the above characteristics, stability under abnormal conditions can be ensured while maintaining the performance of the electrode, electrode assembly, or secondary battery even when storage of the electrode, electrode assembly, or secondary battery is performed at a relatively high temperature.

[0046] The above intermediate layer or electrode can be configured to exhibit a characteristic in which the absolute value of △R4 of Equation 4 below is 50% or more.

[0047] [Equation 4]

[0048] △R4 = 100 × (C1-C3) / C1

[0049] In Equation 4, C1 is the discharge capacity at room temperature (about 25°C), and C3 is the discharge capacity after storage at 130°C for 10 minutes.

[0050] C1 and C3 in Equation 4 are discharge capacities measured for a coin cell to which the electrode is applied, and the specific method of measuring this is summarized in the examples.

[0051] The absolute value of △R4 in Equation 4 may be 52% or more, 54% or more, 56% or more, 58% or more, 60% or more, 62% or more, 64% or more, 66% or more, 68% or more, 70% or more, 72% or more, 74% or more, or 76% or more. The above absolute value may be 200% or less, 180% or less, 160% or less, 140% or less, 120% or less, 100% or less, 95% or less, 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, or 60% or less. The range of the above absolute value may be within the range of any one of the aforementioned upper limits and any one of the aforementioned lower limits. By designing the electrode to ensure the above characteristics, stability can be secured even under abnormal conditions.

[0052] The characteristics of the electrode as described above can be achieved through the introduction of an intermediate layer described later.

[0053] As for the current collector layer applied to the above electrode, a current collector layer typically used for an anode or cathode can be used without any special limitations.

[0054] As for the current collector layer, as long as it is conductive without causing chemical changes in the application device such as a secondary battery, its type, size, and shape are not particularly limited. Examples of materials that can be used as the current collector layer include copper, aluminum, stainless steel, nickel, titanium, or calcined carbon, or materials surface-treated with carbon, nickel, titanium, or silver on the surface of copper, aluminum, or stainless steel may be exemplified. The current collector layer may be in the form of a film, sheet, foil, net, porous body, foam, or nonwoven fabric containing the above materials. In some cases, a known surface treatment may be performed on the surface of the current collector layer to improve adhesion to other layers, such as an intermediate layer or an active material layer.

[0055] Such a current collector layer may typically have a thickness within the range of 3 μm to 500 μm, but is not limited thereto.

[0056] A layer that is typically applied as the above active material layer can also be used.

[0057] Typically, the active material layer comprises an electrode active material. There are no specific restrictions on the specific type of the electrode active material, and a material that forms a positive electrode or a negative electrode can be used.

[0058] For example, when the above active material layer is a positive electrode active material layer, the electrode active material is a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; lithium iron oxide such as LiFe3O4; and a compound with the chemical formula Li 1+c1 Mn 2-c1 Lithium manganese oxides such as O4 (0≤c1≤0.33), LiMnO3, LiMn2O3, or LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, or Cu2V2O7; chemical formula LiNi 1-c2 M c2 Ni-site type lithium nickel oxide represented by O2 (wherein M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, satisfying 0.01≤c2≤0.3); chemical formula LiMn 2-c3 M c3A lithium manganese composite oxide represented by O2 (wherein M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn and Ta, satisfying 0.01≤c3≤0.1) or Li2Mn3MO8 (wherein M is at least one selected from the group consisting of Fe, Co, Ni, Cu and Zn); may be a lithium nickel cobalt manganese (NCM) composite oxide, a lithium nickel cobalt manganese aluminum (NCMA) composite oxide, and LiMn2O4 in which part of the Li of the chemical formula is substituted with an alkaline earth metal ion, but is not limited thereto.

[0059] When the above active material layer is a negative electrode active material layer, a compound capable of reversible intercalation and deintercalation of lithium may be used as the electrode active material. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, or Al alloys; and SiO₂ a Examples include metal oxides capable of doping and dedoping lithium, such as (0 < a < 2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites comprising the metal compound and carbonaceous material, such as Si-C composites or Sn-C composites, and any one or more of these may be used.

[0060] As the above-mentioned cathode active material, a lithium thin film may be used, and as a carbon material, low-crystallinity carbon and high-crystallinity carbon may be used. Representative examples of low-crystallinity carbon include soft carbon and hard carbon, while representative examples of high-crystallinity carbon include amorphous, plate-like, flake-like, spherical, or fibrous natural 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.

[0061] The above electrode active material may be included in the active material layer in a range of about 80% to 99.5% by weight or 88% to 99% by weight relative to the total weight of the active material layer, but the above ratio may be changed depending on the use or design of the electrode.

[0062] The active material layer may additionally include a binder. The binder serves to improve adhesion between active materials and adhesion between the active material layer and the current collector layer. Examples of the above binders are not particularly limited, and include, for example, PVDF (Poly(vinylidene fluoride)), PVA (poly(vinyl alcohol)), SBR (styrene butadiene rubber), PEO (poly(ethylene oxide)), CMC (carboxyl methyl cellulose), cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, cyanoethylpullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, One or more materials may be selected from the group consisting of polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate copolymer, and polyarylate.

[0063] In one example, the binder may be included in the active material layer in a range of 0.1 to 10 parts by weight or 0.5 to 5 parts by weight relative to 100 parts by weight of the electrode active material, but is not limited thereto.

[0064] The above active material layer may additionally include a conductive material as needed. As for the conductive material, any known material may be used without special limitations as long as it is conductive without causing chemical changes in the secondary battery. For example, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, Farnes black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; conductive tubes such as carbon nanotubes (CNT); metal powders such as fluorocarbon, aluminum, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide and / or conductive materials such as polyphenylene derivatives may be used.

[0065] The above conductive material may be included in an amount of 0.1 to 20 parts by weight or 0.3 to 10 parts by weight relative to 100 parts by weight of the electrode active material in one example, and may be included in the active material layer, but is not limited thereto.

[0066] The active material layer may optionally include additional known components in addition to the components described above.

[0067] The intermediate layer existing between the current collector layer and the active material layer may include a conductive copolymer. A conductive copolymer is a type of conductive polymer and is distinguished from a conductive polymer in the form of a homopolymer in that it is a conductive polymer containing two or more monomer units.

[0068] As is known, a conductive polymer is a polymer that exhibits conductivity through the conjugation of polymer chains and / or doping, etc.

[0069] By using a conductive polymer in the form of a copolymer, properties such as oxidation potential can be efficiently controlled, thereby effectively forming an electrode exhibiting the aforementioned properties.

[0070] The intermediate layer may be composed solely of the conductive copolymer, or may additionally include the conductive copolymer and other necessary additives. In one example, the intermediate layer may contain the conductive copolymer in an amount of 50% by weight or more, 55% by weight or more, 60% by weight or more, 65% by weight or more, 70% by weight or more, 75% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, or 95% by weight or more, based on the total weight of the intermediate layer. The proportion of the conductive copolymer within the intermediate layer may be approximately 100% by weight or less, 95% by weight or less, or 90% by weight or less. The range of content may be within any one of the aforementioned upper limits and any one of the aforementioned lower limits.

[0071] The oxidation potential of the conductive copolymer or intermediate layer can be adjusted according to the purpose. The method for measuring the oxidation potential is described in the examples of this specification. The oxidation potential varies depending on the electrode and electrolyte applied to the measurement, and the oxidation potential in this application is Li / Li + It is measured based on [the standard]. In the present application, an intermediate layer or electrode with desired characteristics can be formed by controlling the oxidation potential measured by the measurement method described in the following example.

[0072] The oxidation potential may be 2V or higher, 2.1V or higher, 2.2V or higher, 2.3V or higher, 2.4V or higher, 2.5V or higher, 2.6V or higher, 2.7V or higher, 2.8V or higher, 2.9V or higher, 3V or higher, 3.1V or higher, 3.2V or higher, 3.3V or higher, 3.4V or higher, 3.5V or higher, 3.6V or higher, or 3.7V or higher. In other examples, the oxidation potential may be 5V or less, 4.9V or less, 4.8V or less, 4.7V or less, 4.6V or less, 4.5V or less, 4.4V or less, 4.3V or less, 4.2V or less, 4.1V or less, 4.0V or less, 3.9V or less, 3.8V or less, 3.7V or less, 3.6V or less, or 3.5V or less. The oxidation potential may be within the range of any one upper limit among the upper limits described above and any one lower limit among the lower limits described above. By using a conductive copolymer having such an oxidation potential as above, an intermediate layer and an electrode with desired characteristics can be effectively formed.

[0073] The conductive copolymer may have a weight-average molecular weight within a predetermined range. The weight-average molecular weight of the conductive copolymer may be 30,000 g / mol or more, 35,000 g / mol or more, 40,000 g / mol or more, 45,000 g / mol or more, 50,000 g / mol or more, 55,000 g / mol or more, or 60,000 g / mol or more. The above weight-average molecular weight may be 100,000 g / mol or less, 95,000 g / mol or less, 90,000 g / mol or less, 85,000 g / mol or less, 80,000 g / mol or less, 75,000 g / mol or less, 70,000 g / mol or less, 65,000 g / mol or less, 60,000 g / mol or less, 55,000 g / mol or less, or 50,000 g / mol or less. The weight-average molecular weight may be within the range of any one upper limit among the upper limits described above and any one lower limit among the lower limits described above. By using a conductive copolymer having such a weight-average molecular weight, an intermediate layer and an electrode with desired characteristics can be effectively formed.

[0074] The molecular weight distribution of the conductive copolymer, that is, the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn), may be within a predetermined range. In one example, the molecular weight distribution may be 2 or more, 2.5 or more, 3 or more, 3.5 or more, or 4 or more, or 8 or less, 7.5 or less, 7 or less, 6.5 or less, 6 or less, 5.5 or less, 5 or less, 4.5 or less, 4 or less, or 3.5 or less. The molecular weight distribution may be within the range of any one upper limit among the upper limits described above and any one lower limit among the lower limits described above. By using a conductive copolymer having such a molecular weight distribution, an intermediate layer and an electrode with desired characteristics can be effectively formed.

[0075] The above conductive copolymer may be a thiophene copolymer. In this application, the desired intermediate layer can be efficiently formed by applying a thiophene copolymer as the conductive copolymer.

[0076] In this specification, the term "thiophene copolymer" means a copolymer comprising at least 50 mol%, at least 55 mol%, at least 60 mol%, at least 65 mol%, at least 70 mol%, at least 75 mol%, at least 80 mol%, at least 85 mol%, or at least 90 mol% of the polymer units of a thiophene-based monomer relative to the total polymer units of the copolymer. The upper limit of the ratio of the polymer units of the thiophene-based monomer within the thiophene copolymer is not particularly limited and may, for example, be 100 mol% or less, 95 mol% or less, or 90 mol% or less.

[0077] The above thiophene series monomers are monomers containing a thiophene backbone.

[0078] In the present application, as the thiophene copolymer, a copolymer of a thiophene-based monomer containing a fluid functional group (hereinafter referred to as the first monomer) and a thiophene-based monomer containing a hydrophilic functional group (hereinafter referred to as the second monomer) may be applied.

[0079] The above-mentioned fluidity functional group is a functional group capable of imparting appropriate fluidity to the polymerization process of the conductive copolymer or to the conductive copolymer itself. A monomer containing such a fluidity functional group imparts appropriate fluidity to the monomer mixture and also allows it to diffuse within the monomer mixture to enable polymerization to occur with excellent efficiency. Furthermore, the conductive copolymer having a fluidity functional group can enable the stable and uniform formation of an intermediate layer between the current collector and the active material layer through appropriate fluidity.

[0080] As long as the type of fluidity functional group performs the above role, the specific type is not particularly limited, but a chain having a length of at least a certain level can effectively impart the fluidity intended in this application.

[0081] Examples of such fluid functional groups may include alkyl groups, alkoxy groups, alkyl carbonyl groups, or alkyl carbonyloxy groups. Generally, alkyl groups and / or alkoxy groups may be used, but are not limited thereto.

[0082] The number of carbon atoms in each alkyl group included in the above-mentioned fluid functional group, the alkyl group included in the alkyl carbonyl group, and the alkyl group included in the alkyl carbonyloxy may be 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, or 30 or less, 29 or less, 28 or less, 27 or less, 26 or less, 25 or less, 24 or less, 23 or less, 22 or less, 21 or less, 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, or 4 or less. The range of the number of carbon atoms in the above alkyl group may be within the range of any one upper limit among the upper limits described above and any one lower limit among the lower limits described above.

[0083] The number of carbon atoms of the alkoxy group, which is the above-mentioned fluid functional group, may be 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, or 30 or fewer, 29 or fewer, 28 or fewer, 27 or fewer, 26 or fewer, 25 or fewer, 24 or fewer, 23 or fewer, 22 or fewer, 21 or fewer, 20 or fewer, 19 or fewer, 18 or fewer, 17 or fewer, 16 or fewer, 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, 11 or fewer, 10 or fewer, 9 or fewer, 8 or fewer, 7 or fewer, 6 or fewer, 5 or fewer, or 4 or fewer. The range of the number of carbon atoms of the above alkoxy group may be within the range of any one upper limit among the upper limits described above and any one lower limit among the lower limits described above.

[0084] Meanwhile, examples of hydrophilic functional groups present in the second monomer above include hydrophilic functional groups such as carboxyl groups, hydroxyl groups, amino groups, cyano groups, nitro groups, ether groups, or functional groups of Chemical Formula 3 below.

[0085] [Chemical Formula 3]

[0086]

[0087] 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 a number in the range of 1 to 10.

[0088] In Chemical Formula 3, the fact that L4 is a single bond means that L4 is absent, and the oxygen atom between L4 and L3 is directly connected to the second monomer.

[0089] The alkyl group of R5 in Chemical Formula 3 may, in one example, be an alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, or may be a methyl group or an ethyl group. The alkyl group may be straight-chain, branched-chain, or cyclic, and suitably may be straight-chain or branched-chain.

[0090] 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.

[0091] The alkylene groups of L3 and L4 in Formula 3 may each be, in one example, alkylene groups having 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms, or ethylene groups or propylene groups. The alkylene groups may be straight-chain, branched-chain, or cyclic, and suitably may be straight-chain or branched-chain.

[0092] The alkylidene groups of L3 and L4 in Chemical Formula 3 may, in one example, be alkylidene groups having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, or may be methylidene groups, ethylylene groups, or propylidene groups. The alkylidene groups may be straight-chain, branched-chain, or cyclic, and suitably may be straight-chain or branched-chain.

[0093] In Chemical Formula 1, n may be 2 or more, 3 or more, or 4 or more in other examples, or 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, or 3 or less.

[0094] By applying hydrophilic functional groups as described above, an intermediate layer containing a conductive copolymer can be bonded to another layer to have appropriate bonding strength, and the desired protective function can be efficiently achieved by uniformly forming such a layer of conductive copolymer.

[0095] The molar number of the above functional groups (hydrophilic functional groups and fluid functional groups) in the conductive copolymer can be controlled to ensure an appropriate effect.

[0096] For example, the ratio of the molar number of polymerization units formed by the first monomer relative to the total polymerization units of the conductive copolymer may be 50 mol% or more, 55 mol% or more, 60 mol% or more, 65 mol% or more, 70 mol% or more, 75 mol% or more, 80 mol% or more, or 85 mol% or more, or 99 mol% or less, 95 mol% or less, 90 mol% or less, 85 mol% or less, or 80 mol% or less. The ratio of the molar number of polymerization units formed by the first monomer may be within the range of any one of the lower limits described above and any one of the upper limits described above.

[0097] For example, the ratio (M1 / M2) of the number of moles (M1) of polymerization units formed by the first monomer in the conductive copolymer to the number of moles (M2) of polymerization units formed by the second monomer may be approximately 1.5 or more, 2 or more, 2.5 or more, 3 or more, 3.5 or more, 4 or more, 4.5 or more, 5 or more, 5.5 or more, 6 or more, 6.5 or more, 7 or more, 7.5 or more, 8 or more, or 8.5 or more, or 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, or 4 or less. The above ratio M1 / M2 may be within the range of any one upper limit among the upper limits described above and any one lower limit among the lower limits described above. An intermediate layer of the desired characteristic can be efficiently formed within this range.

[0098] Meanwhile, the total moles of polymerization units formed by the first and second monomers in the conductive copolymer may be about 50 mol% or more, 55 mol% or more, 60 mol% or more, 65 mol% or more, 70 mol% or more, 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, or 95 mol% or more, or 100 mol% or less, 95 mol% or less, or 90 mol% or less, relative to the total polymerization units included in the copolymer. The ratio may be within the range of any one upper limit among the upper limits described above and any one lower limit among the lower limits described above.

[0099] In one example, the conductive copolymer may include a polymerization unit of the following chemical formula 1 as a thiophene-based monomer.

[0100] [Chemical Formula 1]

[0101]

[0102] In Chemical Formula 1, R1 and R2 are each independently hydrogen, the hydrophilic functional group, or the fluid functional group, and at least one of R1 and R2 may be the hydrophilic functional group or the fluid functional group.

[0103] In another example, in Chemical Formula 1, R1 and R2 can be connected to each other to form a divalent functional group of Chemical Formula 2 below.

[0104] [Chemical Formula 2]

[0105]

[0106] In Chemical Formula 2, each oxygen atom can be bonded to the carbon atom to which R1 is connected and the carbon atom to which R2 is connected in Chemical Formula 1.

[0107] 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 hydrophilic functional group, or a fluid functional group, wherein at least one of R3 and R4 is a hydrophilic functional group or a fluid functional group.

[0108] The specific types of hydrophilic functional groups and fluid functional groups in chemical formulas 1 and 2 are as described above.

[0109] In addition, the meaning of L1 or L2 being a single bond in Chemical Formula 2 is the same as in the case of L4 in Chemical Formula 3.

[0110] The alkylene groups of L1 and L2 in Formula 2 may each be, in one example, alkylene groups having 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms, or ethylene groups or propylene groups. The alkylene groups may be straight-chain, branched-chain, or cyclic, and suitably may be straight-chain or branched-chain.

[0111] The alkylidene groups of L1 and L2 in Formula 2 may each be, in one example, alkylidene groups having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, or may be methylidene groups, ethylylene groups, or propylidene groups. The alkylidene groups may be straight-chain, branched-chain, or cyclic, and suitably may be straight-chain or branched-chain.

[0112] In a specific example, the conductive copolymer may simultaneously include a polymerization unit of Formula 4 and a polymerization unit of Formula 5.

[0113] The polymerization unit of Chemical Formula 4 below is an example of the polymerization unit of the first monomer described above, and the polymerization unit of Chemical Formula 5 below is an example of the polymerization unit of the second monomer described above.

[0114] [Chemical Formula 4]

[0115]

[0116] In Chemical Formula 4, R6 and R7 are each independently hydrogen or the above-mentioned fluid functional group, and at least one of R6 and R7 is the above-mentioned fluid functional group.

[0117] The specific details regarding the above-mentioned fluid functional group are as described above.

[0118] In another example, R6 and R7 of the above chemical formula 4 may be connected to each other to form the divalent functional group of the following chemical formula 6.

[0119] [Chemical Formula 6]

[0120]

[0121] In Chemical Formula 6, L5 and L6 are each independently a single bond, an alkylene group, or an alkylidene group, and R 10 and R 11 Each is independently a hydrogen or a fluid functional group, R 10 and R 11 One or more of them are fluid functional groups.

[0122] The specific types of fluid functional groups in chemical formulas 4 and 6 are as described above.

[0123] In addition, the meaning of L5 or L6 being a single bond in Chemical Formula 6 is the same as in the case of L4 in Chemical Formula 3.

[0124] The alkylene groups of L5 and L6 in Chemical Formula 6 may, in one example, be alkylene groups having 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms, or may be ethylene groups or propylene groups. The alkylene groups may be straight-chain, branched-chain, or cyclic, and suitably may be straight-chain or branched-chain.

[0125] The alkylidene groups of L5 and L6 in Chemical Formula 6 may, in one example, be alkylidene groups having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, or may be methylidene groups, ethylylene groups, or propylidene groups. The alkylidene groups may be straight-chain, branched-chain, or cyclic, and suitably may be straight-chain or branched-chain.

[0126] [Chemical Formula 5]

[0127]

[0128] In Chemical Formula 5, R8 and R9 are each independently hydrogen or the hydrophilic functional group, and at least one of R8 and R9 may be the hydrophilic functional group.

[0129] In another example, R8 and R9 of the above chemical formula 5 may be connected to each other to form a divalent functional group of the following chemical formula 7.

[0130] [Chemical Formula 7]

[0131]

[0132] In Chemical Formula 7, L7 and L8 are each independently a single bond, an alkylene group, or an alkylidene group, and R 12 and R 13Each is independently a hydrogen or hydrophilic functional group, R 12 and R 13 One or more of them may be hydrophilic functional groups.

[0133] The specific types of hydrophilic functional groups in chemical formulas 5 and 7 are as described above.

[0134] In addition, the meaning of L7 or L8 being a single bond in Chemical Formula 7 is the same as in the case of L4 in Chemical Formula 3.

[0135] The alkylene groups of L7 and L8 in Formula 7 may each be, in one example, alkylene groups having 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms, or ethylene groups or propylene groups. The alkylene groups may be straight-chain, branched-chain, or cyclic, and suitably may be straight-chain or branched-chain.

[0136] The alkylidene groups of L7 and L8 in Formula 7 may, in one example, be alkylidene groups having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, or may be methylidene groups, ethylylene groups, or propylidene groups. The alkylidene groups may be straight-chain, branched-chain, or cyclic, and suitably may be straight-chain or branched-chain.

[0137] For example, the ratio of the molar number of the polymerization unit of Formula 4 to the total polymerization unit of the conductive copolymer may be 50 mol% or more, 55 mol% or more, 60 mol% or more, 65 mol% or more, 70 mol% or more, 75 mol% or more, 80 mol% or more, or 85 mol% or more, or 99 mol% or less, 95 mol% or less, 90 mol% or less, 85 mol% or less, or 80 mol% or less. The ratio of the molar number of the polymerization unit of Formula 4 may be within the range of any one of the lower limits described above and any one of the upper limits described above.

[0138] For example, the ratio (M1 / M2) of the number of moles (M1) of the polymerization unit of Formula 4 to the number of moles (M2) of the polymerization unit of Formula 5 in the conductive copolymer may be approximately 1.5 or more, 2 or more, 2.5 or more, 3 or more, 3.5 or more, 4 or more, 4.5 or more, 5 or more, 5.5 or more, 6 or more, 6.5 or more, 7 or more, 7.5 or more, 8 or more, or 8.5 or more, or 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, or 4 or less. The above ratio M1 / M2 may be within the range of any one upper limit among the upper limits described above and any one lower limit among the lower limits described above. An intermediate layer of the desired characteristic can be efficiently formed within this range.

[0139] Meanwhile, the total moles of the polymerization units of Formulas 4 and 5 in the conductive copolymer may be about 50 mol% or more, 55 mol% or more, 60 mol% or more, 65 mol% or more, 70 mol% or more, 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, or 95 mol% or more, or 100 mol% or less, 95 mol% or less, or 90 mol% or less, relative to the total polymerization units included in the copolymer. The ratio may be within the range of any one upper limit among the upper limits described above and any one lower limit among the lower limits described above.

[0140] The conductive copolymer may additionally include other polymerization units as long as it includes the aforementioned units in the above proportions.

[0141] The intermediate layer comprises the conductive copolymer and, accordingly, can exhibit the aforementioned characteristics.

[0142] The intermediate layer may also include any additional components as long as it contains the conductive copolymer.

[0143] The thickness of the above intermediate layer may be approximately 10 nm or more, 50 nm or more, 100 nm or more, 150 nm or more, 200 nm or more, 250 nm or more, 300 nm or more, 350 nm or more, 400 nm or more, 450 nm or more, or 500 nm or more, or may be within a range of approximately 2 μm or less, 1.5 μm or less, 1 μm or less, 950 nm or less, 900 nm or less, 850 nm or less, 800 nm or less, 750 nm or less, 700 nm or less, 650 nm or less, 600 nm or less, 550 nm or less, 500 nm or less, 450 nm or less, 400 nm or less, 350 nm or less, or 300 nm or less. The thickness may be within the range of any one upper limit among the upper limits described above and any one lower limit among the lower limits described above.

[0144] This application also relates to a method for manufacturing the electrode.

[0145] The manufacturing method of the present application may include the steps of forming the intermediate layer on the current collector layer and forming the active material layer on the intermediate layer.

[0146] There are no particular limitations on the method of forming the above intermediate layer on the current collector layer. For example, the above intermediate layer can be formed by preparing a coating solution by diluting the aforementioned conductive copolymer and, if necessary, other additives in a suitable solvent, coating it onto the current collector, and then drying it.

[0147] In another example, the monomers forming the conductive copolymer may be directly polymerized on the current collector layer to form the intermediate layer.

[0148] The preparation of the coating composition and the coating method for forming the above intermediate layer are not particularly limited, and methods from known coating methods may be applied. Furthermore, the method for polymerizing the above conductive copolymer is not particularly limited, and known methods may be applied. For example, methods for manufacturing polythiophene are typically known to utilize oxidative polymerization or radical reactions, and such methods may also be applied to the process of forming the above conductive copolymer in this application.

[0149] In addition, in the manufacturing process of the present application, a subsequent process such as an appropriate drying process may be additionally performed following the coating and / or polymerization process.

[0150] There are no particular limitations on the method of forming the active material layer on the intermediate layer. Typically, the active material layer is formed by coating a slurry containing the electrode active material, binder, and conductive material onto the current collector (intermediate layer), drying, and then rolling; such known methods may be applied in the present application as well.

[0151] The present application also relates to an electrode assembly or electrochemical device comprising an electrode as described above, for example, a secondary battery.

[0152] The above electrochemical device may include the electrode as a positive electrode and / or a negative electrode. As long as the electrode of the present application is used as a negative electrode and / or a positive electrode, other configurations or manufacturing methods of the electrochemical device are not particularly limited, and known methods may be applied. Effects of the invention

[0153] The present application relates to electrodes and their uses. The present application provides an electrode and its uses that, under normal and storage conditions, exhibit low resistance so as not to affect the performance and operation of a secondary battery, and, under abnormal conditions caused by overcharging, exposure to high temperatures, or external shock, block current flow in the electrode assembly through an increase in resistance to ensure stability. The present application provides an electrode and its uses that can variably control the movement of charge according to the internal temperature of a secondary battery. Brief explanation of the drawing

[0154] FIG. 1 is a cross-sectional view of an exemplary electrode of the present application. Figure 2 is the result of NMR analysis for the monomer of Preparation Example 1. Figure 3 is the result of NMR analysis for the monomer of Preparation Example 2. Specific details for implementing the invention

[0155] The contents of the present application will be specifically explained through the following examples and comparative examples, but the scope of the present application is not limited by the following examples.

[0157] 1. NMR Analysis Method

[0158] 1 H-NMR analysis was performed at room temperature using an NMR spectrometer including a Bruker UltraShield spectrometer (300 MHz) equipped with a triple resonance 5 mm probe. The sample was diluted to a concentration of approximately 10 mg / ml in an NMR measurement solvent (CDCl3), and the chemical shift was expressed in ppm.

[0160] 2. GPC (Gel Permeation Chromatograph)

[0161] Molecular weight characteristics were measured using Gel Permeation Chromatography (GPC). The sample was placed in a 5 mL vial and diluted in chloroform to a concentration of approximately 1 mg / mL. Subsequently, the standard sample for calibration and the sample to be analyzed were filtered through a syringe filter (pore size: 0.45 μm) before measurement. Waters Empower 3 was used as the analysis program; the weight-average molecular weight (Mw) and number-average molecular weight (Mn) were determined by comparing the sample elution time with the calibration curve, and the molecular weight distribution (PDI) was calculated using the ratio (Mw / Mn). The GPC measurement conditions are as follows.

[0162] <GPC 측정 조건>

[0163] Device: Waters 2414

[0164] Column: 3 Waters Styragels used

[0165] Solvent: THF (Tetrahydrofuran)

[0166] Column temperature: 35℃

[0167] Sample concentration: 1 mg / mL, 1 μL injection

[0168] Standard Sample: Polystyrene (Mp : 3900000, 723000, 316500, 52200, 31400, 7200, 3940, 485)

[0170] 3. Thickness measurement

[0171] The thickness of the intermediate layer, etc., was measured by taking a Scanning Electron Microscope (SEM) image (Hitachi, S4800) after cross-sectionally processing the electrode using an ion milling machine (Hitachi, IM4000).

[0173] 4. Oxidation Potential Measurement Method

[0174] The oxidation potential was measured in the following manner. An intermediate layer with a thickness of approximately 10 μm was formed using a conductive copolymer on an aluminum foil (Al Foil) with a thickness of approximately 15 μm (the intermediate layer was formed in the manner described in Example 1). Subsequently, a separator and a lithium film were laminated onto the intermediate layer to produce a laminate comprising the intermediate layer / aluminum foil / separator / lithium film, which was then die-cut into a circle with a diameter of approximately 1.4 cm. A coin cell was manufactured using the die-cut circular laminate and an electrolyte (using the Welcos CR2032 Coin Cell Kit). As mentioned above, the WL20C model from W-Scope Korea was used as the separator, a lithium film with a thickness of about 100 μm was used, and as the electrolyte, a 1M LiPF6 solution (solvent: EC / DMC / EMC=3 / 4 / 3 (mass ratio), EC: Ethylene Carbonate, DMC: dimethyl carbonate, EMC: ethylmethyl carbonate) from Enchem was used.

[0175] The oxidation potential of the above coin cell was measured at 25°C using a potentiostat (manufacturer: Princeton Applied Research, product name: PARASTAT-MC). The oxidation potential was measured by cyclic voltammetry (CV) at a scan rate of 0.17 mV / sec to 0.5 mV / sec in the range of 1.5 V to 5.5 V.

[0177] 5. DC Resistance Measurement Method

[0178] DC resistance was evaluated using the same coin cell used for 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).

[0180] 6. Interface resistance (AC impedance resistance)

[0181] Interfacial resistance was evaluated using Electrochemical Impedance Spectronization (EIS) with the same coin cell used for oxidation potential measurement. A voltage of 4.3 V was applied to the coin cell at room temperature (25°C) for 10 minutes, and the interfacial resistance obtained in the High Frequency region of the Nyquist plot obtained by the EIS measurement method at 50,000 Hz to 0.1 Hz was measured. An electrochemical potentiostat (manufacturer: Princeton Applied Research, product name: PARASTAT-MC) was used as the EIS measuring instrument.

[0183] 7. Measurement of Maximum Rate of Change in Resistance (DC Resistance)

[0184] The maximum resistance change rate △R1 is determined according to the following Equation 1.

[0185] <Equation 1>

[0186] △R1 = Max{(R n+5 / R n ) / 5}

[0187] R in Equation 1 n is a DC resistance at any temperature n℃ within the range of 25℃ to 135℃, and R n+5 is the DC resistance at a temperature 5°C higher than the above temperature n°C ((n+5)°C).

[0188] The above △R1 is measured in the following manner.

[0189] A coin cell for measuring DC resistance is placed in the center of a convection oven (Manufacturer: Jiotec, Product Name: OF3-05W), and the oven temperature is set to an initial temperature of 25°C, a final temperature of 135°C, and to increase by 5°C per minute. The coin cell is connected to an external resistance multimeter (Fluke's digital multimeter (FLUKE-87-5)) to enable resistance measurement. Subsequently, with the temperature increasing as set, DC resistance is measured at each temperature (measuring up to 135°C while increasing the measurement temperature by 5°C in the order of 25°C, 30°C, 35°C, and 40°C). For each measurement temperature, R in Equation 1 n and R n+5 Measure each, and R n+5 / R n (R 30 / R 25 , R 35 / R 30 ~ R 135 / R 130 After calculating ), divide it again by 5.

[0190] In the temperature range of 25℃ to 135℃, the above (R n+5 / R n After calculating ) / 5, the maximum value among them is calculated as △R1.

[0191] Through the above △R1, the temperature responsiveness of the resistance increase of the conductive copolymer at the on-set temperature can be confirmed.

[0192] The above On-Set temperature is, (R n+5 / R n ) / 5 is the temperature n℃ at which the maximum value is observed.

[0193] The same coin cell used for the above DC resistance measurement was used as the one applied during the oxidation potential measurement.

[0195] 8. Measurement of Maximum Rate of Resistance Change (AC Impedance)

[0196] The maximum resistance change rate △R2 is determined according to Equation 2 below.

[0197] <Equation 2>

[0198] △R2 = Max{(R z+5 / R z ) / 5}

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

[0200] The above △R2 is measured in the following manner.

[0201] A coin cell for measuring AC impedance resistance is placed in the center of a convection oven (Manufacturer: Jiotec, Product Name: OF3-05W), and the oven temperature is set to an initial temperature of 25°C, a final temperature of 135°C, and to increase by 5°C per minute. The coin cell is connected to an external resistance meter to enable resistance measurement. Subsequently, with the temperature increasing as set, the AC impedance resistance is measured at each temperature (measuring up to 135°C while increasing the measurement temperature by 5°C in the order of 25°C, 30°C, 35°C, and 40°C). For each measurement temperature, R in Equation 2 z and R z+5 Measure each, and R z+5 / R z (R 30 / R 25 , R 35 / R 30 ~ R 135 / R 130 After calculating ), divide it again by 5.

[0202] In the temperature range of 25℃ to 135℃, the above (R z+5 / R z After calculating ) / 5, the maximum value among them is calculated as △R2.

[0203] Through the above △R2, the temperature responsiveness of the resistance increase of the conductive copolymer at the on-set temperature can be confirmed.

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

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

[0206] In the above, the AC impedance resistance was determined by applying a voltage of 4.3V for 10 minutes, similar to the interface resistance measurement, and taking the resistance obtained from the semicircle in the High Frequency region of the Nyquist plot obtained by the EIS measurement method at 50,000 Hz to 0.1 Hz.

[0208] 9. Discharge Capacity Measurement

[0209] The discharge capacity to verify the result of Equation 3 below was evaluated by the following method.

[0210] <Equation 3>

[0211] △R3 = 100 × (C1-C2) / C1

[0212] In Equation 3, △R3 is the rate of change (%) of discharge capacity, C1 is the discharge capacity at room temperature (about 25℃), and C2 is the discharge capacity after storage at 70℃ for 60 hours.

[0213] A coin cell (reference capacity: 200 mAh / g) for verifying the discharge capacity of Equation 3 was fabricated in the following manner. The coin cell was fabricated using a CR2032 standard coin cell kit (Welcos CR2032 coin cell kit). The electrode prepared in the example or comparative example was used as the positive electrode, and a lithium film (thickness: 100 μm) was used as the negative electrode. As the electrolyte, a 1M LiPF6 solution (solvent: EC / DMC / EMC=3 / 4 / 3 (mass ratio), EC: Ethylene Carbonate, DMC: dimethyl carbonate, EMC: ethylmethyl carbonate) was used as the carbonate-based electrolyte, and a PE (poly(ethylene)) separator (WL20C model from W-Scope Korea) was used as the separator.

[0214] For the above coin cell, one charge / discharge cycle was performed at 25°C, and the capacity at 0.2C was set as the discharge capacity of Equation 3 above. One charge / discharge cycle means that the process of charging at a rate of 0.2C using the CC (Constant Current) / CV (Constant Voltage) method with the charge termination voltage set to 4.5V and the charge termination current to 1mA, and discharging at a rate of 0.2C using the CC (Constant Current) method with the discharge termination voltage set to 3.0V, was repeated once as one cycle. The discharge capacity after one charge / discharge cycle was applied as the discharge capacity (C1, C2) of Equation 3 above.

[0215] C1 was obtained by applying the above measurement method immediately after the coin cell was made, and then C2 was obtained by applying the above measurement method after storing the coin cell at 70°C for 60 hours.

[0217] 10. Discharge Capacity Measurement

[0218] The discharge capacity to verify the result of Equation 4 below was evaluated in the following manner.

[0219] <Equation 4>

[0220] △R4 = 100 × (C1-C3) / C1

[0221] In Equation 4, △R4 is the rate of change (%) of discharge capacity, C1 is the discharge capacity at room temperature (about 25℃), and C3 is the discharge capacity after being stored at 70℃ for 60 hours followed by being stored again at 130℃ for 10 minutes.

[0222] The coin cell for verifying the discharge capacity of Equation 4 was manufactured in the same way as the coin cell for verifying Equation 3, and the discharge capacity measurement was also performed in the same way.

[0223] That is, C1 is obtained by applying the above Equation 3 to the measurement method immediately after making the coin cell to verify it.

[0224] After that, the coin cell was stored at 70°C for 60 hours, followed by storage at 130°C for 10 minutes, and then C3 was obtained.

[0225] C3 was calculated in the following manner. The charging cutoff voltage was set to 4.5V and the charging cutoff current to 1mA, and the charge was charged at a rate of 0.5C using the CC (Constant Current) / CV (Constant Voltage) method. Then, the discharge cutoff voltage was set to 3.0V and the discharge was discharged at a rate of 2C using the CC (Constant Current) method. This process was defined as one cycle and repeated 30 times. The discharge capacity after 30 charge / discharge cycles was applied as C3 in Equation 4. The 30 charge / discharge cycles were performed at 45℃.

[0227] Preparation Example 1. Synthesis of monomer (A)

[0228] The monomer of the following chemical formula A was synthesized in the following manner.

[0229] [Chemical Formula A]

[0230]

[0231] In chemical formula A, R1 and R2 are straight-chain butyl groups.

[0233] The monomer of chemical formula A (monomer (A)) (3,4-[3,3'-dibutylpropylenedioxy]thiophene) was synthesized following the process of reaction scheme 1 below.

[0234] [Reaction Equation 1]

[0235]

[0236] 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 reacted under reflux at 120°C, and the methanol produced by transetherification was removed using a Type 4A molecular sieve packed with a Soxhlet extractor. After refluxing for 24 hours, the reaction mixture was quenched with water, extracted with ethyl acetate, washed with brine, and dried over magnesium sulfate (MgSO4). The solvent was removed using a rotary evaporator, and the residue was purified by column chromatography with a methylene chloride / hexane (1:4) elution to obtain the compound 1 (3,4-(3,3'-dibutylpropylenedioxy)thiophene).

[0237] The NMR analysis results for the above target compound (monomer (A)) are as shown in Fig. 2.

[0240] Preparation Example 2. Synthesis of monomer (B)

[0241] The monomer of the following chemical formula B was synthesized in the following manner.

[0242] [Chemical Formula B]

[0243]

[0244] 1.372 g (12.02 mmol, 1 eq) of 3-methoxythiophene and 3 g (16.83 mmol, 1.4 eq) of triethylene glycol monomethyl ether were dissolved in 100 ml of toluene with 230 mg of p-toluenesulfonic acid (p-TsOH) and mixed. The mixture was reacted under reflux at 120°C, and the methanol produced by transetherification was removed using a Type 4A molecular sieve packed with a Soxhlet extractor. After refluxing for 24 hours, the reaction mixture was quenched with water, extracted with ethyl acetate, washed with brine, and dried over magnesium sulfate (MgSO4). The solvent was removed using a rotary evaporator, and the residue was purified by column chromatography with a methylene chloride / hexane (2:1) elution to obtain the target compound (monomer (B)). The NMR analysis results for the target compound (monomer (B)) are shown in Fig. 3.

[0246] Example 1.

[0247] Synthesis of polythiophene (A)

[0248] Polythiophene (A) was prepared by adding 1.58 g (5.91 mmol, 0.9 eq) of the monomer (A) of Preparation Example 1 and 0.16 g (0.66 mmol, 0.1 eq) of the monomer (B) of Preparation Example 2 to a solution in which 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride was dissolved in 150 ml of methylene chloride, and polymerizing at 25°C for 24 hours.

[0249] After placing the polymerization solution in an osmotic membrane with a molecular weight of cut-off (MWCO) of 5000, it was immersed in 200 ml of acetonitrile solvent to remove unreacted iron chloride (III), monomer (A), monomer (B), and low molecular weight oligomers. The residue precipitated inside the osmotic membrane was washed with methanol and dried at 60°C for 12 hours to produce polythiophene (A).

[0250] Polythiophene (A) had a weight-average molecular weight (Mw) and a number-average molecular weight (Mn) of 60,200 g / mol and 18,500 g / mol, respectively, and an oxidation potential of about 3.5 V.

[0252] Manufacturing of electrodes

[0253] As a current collector, an Al foil with a thickness of approximately 15 μm was used. The polythiophene (A) prepared above was dispersed in a solvent (chloroform) at a concentration of approximately 2.0 wt% to prepare a coating solution. The coating solution was coated onto the current collector using a bar coating method and maintained at 90°C for 30 minutes to form a layer (intermediate layer) with a thickness of approximately 300 nm. Subsequently, an active material layer was formed on the intermediate layer. The above active material layer was formed by applying a slurry containing lithium cobalt oxide (LiCoO2), carbon-based conductive material (ECP (Ketjen Black) 0.5%, SFG (Trimrex graphite) 0.4%, DB (Denka Black) 0.4%), PVDF (polyvinylidene fluoride), and NMP (N-Methyl-2-pyrrolidone) in a weight ratio of 75:1:1:23 (LiCoO2:conductive material:PVDF:NMP) onto the intermediate layer with a thickness of about 90 μm using a doctor blade, drying at room temperature, and then further drying under vacuum conditions at 120°C. Subsequently, an electrode was manufactured by rolling to achieve a porosity of about 25%.

[0255] Example 2.

[0256] An electrode was manufactured in the same manner as in Example 1, except that the intermediate layer was formed to a thickness of about 500 nm.

[0258] Example 3.

[0259] Synthesis of polythiophene (C)

[0260] Polythiophene (C) was prepared by adding 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 Preparation Example 1 to a solution in which 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride was dissolved in 150 ml of methylene chloride, and polymerizing at 25°C for 24 hours. The weight ratio (A:B) of monomer (A) units and monomer (B) units of preparation Example 1 in polythiophene (C) is approximately 4:1.

[0261] After placing the polymerization solution in an osmotic membrane with a molecular weight of cut-off (MWCO) of 5000, the unreacted iron chloride (III) and monomer were removed by immersing it in 200 ml of acetonitrile solvent. The residue precipitated inside the osmotic membrane was washed with methanol and dried at 60°C for 12 hours to produce polythiophene (C).

[0262] Polythiophene (C) had a weight-average molecular weight (Mw) and a number-average molecular weight (Mn) of 48,300 g / mol and 11,200 g / mol, respectively, and an oxidation potential of about 3.55 V.

[0264] Manufacturing of electrodes

[0265] The electrode was prepared in the same manner as in Example 1, and the thickness of the intermediate layer was about 300 nm.

[0267] Example 4.

[0268] Synthesis of polythiophene (B)

[0269] Polythiophene (B) was prepared by adding 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 Preparation Example 2 to a solution in which 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride was dissolved in 150 ml of methylene chloride, and polymerizing at 25°C for 24 hours. The weight ratio (3-OT:B) of the 3-octylthiophene units (3-OT) prepared from polythiophene (B) and the units of the monomer (B) of Preparation Example 2 is approximately 7:1.

[0270] After placing the polymerization solution in an osmotic membrane with a molecular weight of cut-off (MWCO) of 5000, the unreacted iron chloride (III) and monomer were removed by immersing it in 200 ml of acetonitrile solvent. The residue precipitated inside the osmotic membrane was washed with methanol and dried at 60°C for 12 hours to produce polythiophene (B).

[0271] Polythiophene (B) had a weight-average molecular weight (Mw) and a number-average molecular weight (Mn) of 56,500 g / mol and 12,800 g / mol, respectively, and an oxidation potential of about 3.7 V.

[0273] Manufacturing of electrodes

[0274] The electrode was prepared in the same manner as in Example 1, and the thickness of the intermediate layer was about 300 nm.

[0276] Example 5.

[0277] Synthesis of polythiophene (D)

[0278] Polythiophene (D) was prepared by 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) to a solution of 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride dissolved in 150 ml of methylene chloride and polymerizing at 25°C for 24 hours. The weight ratio (3-OT:B) of the 3-octylthiophene unit (3-OT) and the monomer (B) in polythiophene (D) is approximately 3:1.

[0279] After placing the polymerization solution in an osmotic membrane with a molecular weight of cut-off (MWCO) of 5000, the unreacted iron chloride (III) and monomer were removed by immersing it in 200 ml of acetonitrile solvent. The residue precipitated inside the osmotic membrane was washed with methanol and dried at 60°C for 12 hours to produce polythiophene (D).

[0280] Polythiophene (D) had a weight-average molecular weight (Mw) and a number-average molecular weight (Mn) of 45,700 g / mol and 10,300 g / mol, respectively, and an oxidation potential of about 3.7 V.

[0282] Manufacturing of electrodes

[0283] The electrode was prepared in the same manner as in Example 1, and the thickness of the intermediate layer was about 500 nm.

[0285] Comparative Example 1.

[0286] An electrode was manufactured in the same manner as in Example 1, except that an intermediate layer was not formed.

[0288] Comparative Example 2.

[0289] Synthesis of polythiophene(F)

[0290] Polythiophene (F) was prepared by adding 3-octylthiophene (6.56 mmol, 1.29 eq) to a solution in which 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride was dissolved in 150 ml of methylene chloride, and polymerizing at 25°C for 24 hours.

[0291] After placing the polymerization solution in an osmotic membrane with a molecular weight of cut-off (MWCO) of 5000, the unreacted iron chloride (III) and monomer were removed by immersing it in 200 ml of acetonitrile solvent. The residue precipitated inside the osmotic membrane was washed with methanol and dried at 60°C for 12 hours to produce polythiophene (F).

[0292] Polythiophene (F) had a weight-average molecular weight (Mw) and a number-average molecular weight (Mn) of 59,200 g / mol and 17,400 g / mol, respectively, and an oxidation potential of about 3.7 V.

[0294] Manufacturing of electrodes

[0295] The electrode was prepared in the same manner as in Example 1, and the thickness of the intermediate layer was about 300 nm.

[0297] The measurement results for the electrode manufactured above are summarized in Tables 1 and 2 below. In Tables 1 and 2 below, C1 in Equation 3 and C1 in Equation 4 should theoretically show the same value, but during the actual experiment, some difference occurred within the margin of error.

[0298] Examples 1 2 3 4 5 DC resistance (Ω·cm) 350 608 432 412 489 Interfacial resistance (AC impedance) (Ω) 48 72 57 66 89 Equation 1 △R1 208.3 277.2 179.8 412.5 354.2 On Set(℃) 90 90 95 90 95 Equation 2 △R2 18.8 23.3 15.4 33.2 27.3 On Set(℃) 90 90 95 90 95 Equation 3 C1 198.3 193.3 199.2 195.4 196.9 C2 195.5 189.8 197.8 192.2 194.7 △R3 1.4 1.8 0.7 1.6 -0.4 Equation 4 C1 198.1 193.5 198.7 196.2 199.8 C3 65.2 45.5 78.9 61.3 80.8 △R4 67 76.5 60.3 68.8 59.6

[0299] Comparative example 1 2 DC resistance (Ω·cm) 5.3 335.2 Interfacial resistance (AC impedance) (Ω) 2.1 45 Equation 1 △R1 1.2 253 On Set(℃) - 80 Equation 2 △R2 2.5 33.4 On Set(℃) - 75 Equation 3 C1 199.8 198.7 C2 198.5 133.7 △R3 0.7 32.7 Equation 4 C1 199.2 197.8 C3 165.4 56.7 △R4 17 71.3

[0301] Through Tables 1 and 2, it can be confirmed that the electrode according to the present application exhibits characteristics such as low resistance in storage conditions, which does not affect the performance and operation of the secondary battery, and, in abnormal conditions caused by overcharging, exposure to high temperatures, or external shock, blocking the current flow of the electrode assembly through an increase in resistance to ensure stability.

[0302] On the other hand, in the case of Comparative Example 1, which lacks an intermediate layer, no increase in resistance occurred even under high temperature conditions.

[0303] In the case of Comparative Example 2, although resistance increased under high temperature conditions, the onset temperature was low, so resistance increased even when stored under high temperature conditions, which adversely affected the performance of the battery.

Claims

Claim 1 A current collector layer; an active material layer formed on the current collector layer; and an intermediate layer between the current collector and the active material layer, wherein the intermediate layer comprises a conductive copolymer having an oxidation potential of 5.0 V or less, a DC resistance of 800 Ω·cm or less at 25°C, and an AC impedance resistance of 200 Electrode with Ω or less and △R2 in Equation 2 below being 10Ω / ℃ or more: [Equation 2]△R2 = Max{(R z+5 / R z R in Equation 2 ) / 5} z is an AC impedance resistance at any temperature n℃ within the range of 25℃ to 135℃, and R z+5 is the AC impedance resistance at a temperature 5°C higher than the above temperature n°C ((n+5)°C), and Max{(R z+5 / R z ) / 5} is (R confirmed within a temperature range of 25℃ to 135℃ z+5 / R z It is the maximum value among ) / 5 values. Claim 2 An electrode according to claim 1, having a DC resistance of 750 Ω·cm or less at 25℃. Claim 3 An electrode according to claim 1, wherein the AC impedance resistance is 100 Ω or less. Claim 4 In claim 1, the electrode having △R1 of the following Equation 1 equal to 100 Ω·cm / ℃ or more: [Equation 1] △R1 = Max{(R n+5 / R n R in Equation 1 ) / 5} n is a DC resistance at any temperature n℃ within the range of 25℃ to 135℃, and R n+5 is the DC resistance at a temperature 5℃ higher ((n+5)℃) than the above temperature n℃, and Max{(R n+5 / R n ) / 5} is (R confirmed within a temperature range of 25℃ to 135℃ n+5 / R n It is the maximum value among ) / 5 values. Claim 5 In Paragraph 4, R where △R1 is confirmed n Electrode whose temperature exceeds 80℃. Claim 6 An electrode according to claim 1, wherein △R2 of Equation 2 is 14 Ω / ℃ or higher. Claim 7 In claim 1, R in which △R2 is confirmed z An electrode with a temperature of 80℃ or higher. Claim 8 In claim 1, the electrode in which the absolute value of △R3 of the following Equation 3 is less than 10%: [Equation 3] △R3 = 100 × (C1-C2) / C1 In Equation 3, C1 is the discharge capacity at room temperature (about 25℃), and C2 is the discharge capacity after storage at 70℃ for 60 hours. Claim 9 In claim 1, the electrode having an absolute value of △R4 of the following Equation 4 of 50% or more: [Equation 4] △R4 = 100 × (C1-C3) / C1 In Equation 4, C1 is the discharge capacity at room temperature (about 25℃), and C3 is the discharge capacity after storage at 130℃ for 10 minutes. Claim 10 In claim 1, the intermediate layer is an electrode having a thickness within the range of 10 nm to 2 μm. Claim 11 In claim 1, the conductive copolymer comprises an electrode having a polymerization unit of the following Chemical Formula 1: [Chemical Formula 1] In Chemical Formula 1, R1 and R2 are each independently hydrogen, a hydrophilic functional group, or a fluid functional group, wherein at least one of R1 and R2 is a hydrophilic functional group or a fluid functional group, or R1 and R2 are connected to each other to form a divalent functional group of Chemical Formula 2 below: [Chemical Formula 2] In Chemical Formula 2, L1 and L2 are each independently a single bond, an alkylene group, or an alkylidene group, and R3 and R4 are each independently hydrogen, a hydrophilic functional group, or a fluid functional group, wherein at least one of R3 and R4 is a hydrophilic functional group or a fluid functional group. Claim 12 In claim 11, the electrode wherein the hydrophilic functional group is a carboxyl group, a hydroxyl group, an amino group, a cyano group, a nitro group, an ether group, or a functional group of the following chemical formula 3: [Chemical Formula 3] 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 a number in the range of 1 to 10. Claim 13 An electrode according to claim 11, wherein the fluid functional group is an alkyl group having 3 or more carbon atoms, an alkoxy group having 3 or more carbon atoms, an alkyl carbonyl group having 3 or more carbon atoms, or an alkyl carbonyloxy group having 3 or more carbon atoms. Claim 14 In claim 1, the conductive copolymer comprises an electrode comprising a polymerization unit of Formula 4 and a polymerization unit of Formula 5: [Formula 4] In Chemical Formula 4, R6 and R7 are each independently hydrogen or a fluid functional group, wherein at least one of R6 and R7 is a fluid functional group, or R6 and R7 are connected to each other to form the 2-valent functional group of Chemical Formula 6 below: [Chemical Formula 5] In Chemical Formula 5, R8 and R9 are each independently hydrogen or hydrophilic functional groups, wherein at least one of R8 and R9 is a hydrophilic functional group, or R8 and R9 are connected to each other to form a divalent functional group of Chemical Formula 7 below: [Chemical Formula 6] In Chemical Formula 6, L5 and L6 are each independently a single bond, an alkylene group, or an alkylidene group, and R 10 and R 11 Each is independently hydrogen or a fluid functional group, and R 10 and R 11 One or more of them are fluid functional groups: [Formula 7] In Chemical Formula 7, L7 and L8 are each independently a single bond, an alkylene group, or an alkylidene group, and R 12 and R 13 Each is independently a hydrogen or hydrophilic functional group, R 12 and R 13 One or more of them are hydrophilic functional groups. Claim 15 An electrode according to claim 14, wherein the ratio of the molar number of polymerization units of Formula 4 to the total polymerization units of the conductive copolymer is 50 mol% or more. Claim 16 An electrode according to claim 14, wherein the ratio (M1 / M2) of the number of moles (M1) of the polymerization unit of formula 4 to the number of moles (M2) of the polymerization unit of formula 5 is 1.5 to 20 or less. Claim 17 An electrode according to claim 14, wherein the ratio of the total moles of polymerization units of formulas 4 and 5 to the total polymerization units of the conductive copolymer is within the range of 55 mol% to 100 mol%. Claim 18 An electrode assembly comprising the electrode of claim 1. Claim 19 A secondary battery comprising the electrode of claim 1.

Images