Electrode current collector

Abstract

This specification discloses a current collector for an electrode and uses thereof. The current collector for an electrode exhibits excellent electrical properties, including low resistance, under normal conditions, such as in a secondary battery, and can ensure stability through increased resistance under abnormal conditions. This specification also discloses uses of the current collector for an electrode.

Description

[Technical Field]

[0001] Cross-reference to related applications This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0135124, dated October 19, 2022, the entire contents of which are incorporated herein by reference.

[0002] Technical Field The present specification discloses a current collector for an electrode and its use. [Background technology]

[0003] Energy storage technology is finding applications in a wide range of devices, including mobile phones, tablets, laptops, and even electric vehicles.

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

[0005] As major developed countries curb the production of internal combustion engine vehicles in order to eliminate global warming and air pollution, major automakers are also developing a variety of electric vehicles, and the importance of secondary batteries, which have high energy density, high discharge voltage and output stability as a driving source for these vehicles, is becoming increasingly important.

[0006] However, in line with this trend, the frequency of fires or explosions caused by overcharging, exposure to high temperatures, or external impacts is also increasing in devices and automobiles that use secondary batteries as their energy source.

[0007] The main cause of such accidents is known to be a short circuit, which occurs when the positive and negative electrodes inside the electrode assembly come into direct contact due to an external stimulus.When a secondary battery is overcharged, exposed to high temperatures, or exposed to external stimuli, the short circuit can occur due to the contraction of the separator caused by an increase 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 can be concentrated at the point where the positive and negative electrodes are in direct contact, which can accelerate internal heat generation, generating gas inside the battery and causing it to expand in volume, increasing the risk of fire. Summary of the Invention [Problem to be solved by the invention]

[0009] This specification discloses a current collector for an electrode and uses thereof. An object of this specification is to disclose a current collector for an electrode that exhibits excellent electrical properties, such as low resistance, under normal conditions, does not affect the performance and operation of a secondary battery, and ensures stability under abnormal conditions. Another object of this specification is to disclose uses of the current collector for an electrode. [Means for solving the problem]

[0010] As used herein, the term "room temperature" refers to a natural temperature that is neither heated nor cooled. For example, room temperature may be any temperature within the range of 10°C to 30°C, or a temperature of about 23°C, about 25°C, or about 27°C. When the temperature at which a physical property is measured affects a physical property mentioned herein, the physical property is measured at room temperature unless otherwise specified. Unless otherwise specified, the unit of temperature used herein is Celsius (°C).

[0011] As used herein, the term "atmospheric pressure" refers to natural pressure without pressure or decompression, and typically refers to a pressure of about 730 mmHg to 790 mmHg. When the measurement pressure affects a physical property mentioned in this specification, the physical property is measured at atmospheric pressure unless otherwise specified.

[0012] When the humidity at which a physical property is measured affects the results of the physical property referred to in this specification, the physical property is measured at standard humidity unless otherwise specified.

[0013] Humidity under standard conditions means any relative humidity within a range of 40% to 60%, for example, a relative humidity of about 55% or 60%.

[0014] As used herein, the term "normal state" refers to a normal operating state of a secondary battery (for example, a normal charging or discharging state of a secondary battery) or a storage state.

[0015] As used herein, the term "abnormal condition" refers to a dangerous condition in which an abnormal charge flow, abnormal heat generation, or explosion occurs due to an external impact and / or short circuit, or in which the likelihood of such an abnormal condition occurring is increased.

[0016] The present specification discloses a current collector for an electrode.

[0017] The electrode current collector may include a current collector body and a polymer layer formed on the 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 diagram showing an electrode in which an active material layer 300 is formed on the polymer layer 200 of the electrode current collector including the current collector body 100 and the polymer layer 200.

[0018] As shown in the drawings, in the current collector for an electrode or electrode, the current collector body 100 and polymer layer 200, and the polymer layer 200 and active material layer 300 may be in contact with each other, or other elements may be present between them. Also, while the drawings illustrate a case in which 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, two layers of polymer layer 200 may be present 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 one layer may be present between either of the active material layers 300 present on both sides and the current collector body 100.

[0019] The electrode formed of the electrode current collector may be an anode or a cathode applied to a secondary battery.

[0020] The polymer layer can be designed to exhibit a so-called PTC (positive temperature coefficient) effect, which allows the polymer layer to variably control the charge transfer in the current collector or electrode depending on the temperature.

[0021] By applying the polymer layer, the electrode exhibits excellent electrical properties including low resistance under normal conditions, and ensures stability through increased resistance under abnormal conditions.

[0022] In order for a polymer layer to exhibit this effect when applied to an electrode, 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. For example, if the resistance of the polymer layer increases under normal conditions, stable operation of a secondary battery or the like becomes impossible.

[0023] A properly designed PTC effect tendency of the polymer layer enables stable operation of the secondary battery under normal conditions, suppresses abnormal temperature rise under abnormal conditions, and also reduces the rate of temperature rise.

[0024] The polymer layer disclosed herein exhibits the desired PTC effect by controlling the composition of the conductive copolymer and the method of forming the polymer layer. The polymer layer suppresses abnormal overcurrent through the increase in resistance under abnormal conditions, preventing so-called thermal runaway (TR) or thermal propagation (TP), and reduces the risk of heat generation and explosion by preventing volume expansion due to internal gas generation.

[0025] The polymer layer disclosed herein controls the temperature at which the PTC effect occurs and can maintain stable oxidation potential and electrical properties under normal conditions.

[0026] In one example, the upper limit of the DC resistance at 25°C of the polymer layer, the electrode current collector, or the electrode is 10 4 Ω.cm, 9500Ω.cm, 9000Ω.cm, 8500Ω.cm, 8000Ω.cm, 7500Ω.cm, 7000Ω.cm, 6500Ω.cm, 6000Ω.cm, 5500Ω.cm, 5000Ω.c m, 4500Ω.cm, 4000Ω.cm, 3500Ω.cm, 3000Ω.cm, 2500Ω.cm, 2000Ω.cm, 1500Ω.cm, 1000Ω.cm, 950Ω.cm, 900Ω.cm, 850 The DC resistance may be about Ω·cm, 800 Ω·cm, 750 Ω·cm, 700 Ω·cm, 650 Ω·cm, 600 Ω·cm, 550 Ω·cm, 500 Ω·cm, 450 Ω·cm, or 400 Ω·cm, and the lower limit may be about 10 Ω·cm, 50 Ω·cm, 100 Ω·cm, 150 Ω·cm, 200 Ω·cm, 250 Ω·cm, 300 Ω·cm, 350 Ω·cm, 400 Ω·cm, 450 Ω·cm, or 500 Ω·cm. The DC resistance may be less than or equal to any of the upper limits mentioned above; or may be less than or equal to any of the upper limits mentioned above and greater than or equal to any of the lower limits mentioned above. The DC resistance was measured using the method described in "5. DC Resistance Measurement Method" in the Examples section of this specification.

[0027] The upper limit of AC impedance resistance of the polymer layer, electrode current collector, or electrode is 10 3 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 its lower limit may be on the order of 10Ω, 15Ω, 20Ω, 25Ω, 30Ω, 35Ω, 40Ω, 45Ω, 50Ω, 55Ω, 60Ω, 65Ω, or 70Ω. The AC impedance resistance may range up to or below any of the aforementioned upper limits; or may range up to or below any of the aforementioned upper limits but up to or above any of the aforementioned lower limits. The AC impedance resistance was measured by the method described in "6. Interface resistance (AC impedance resistance)" in the Examples of this specification.

[0028] Since the polymer layer, electrode current collector, or electrode exhibits the DC resistance and / or AC impedance resistance, a secondary battery or electrode assembly to which the polymer layer, etc. is applied can be stably operated or stored in a normal state.

[0029] The electrode current collector and electrode to which the polymer layer is applied exhibit a PTC effect in which resistance increases under abnormal conditions, thereby ensuring stability.

[0030] For example, the polymer layer, electrode current collector, or electrode may exhibit a property such that ΔR1 in the following formula 1 falls within a predetermined range.

[0031] [Formula 1] △R1=Max{(R n+5 / R n ) / 5}

[0032] In Equation 1, R n is the DC resistance at any temperature n°C between 25°C and 135°C, and R n+5is the DC resistance at a temperature (n+5)°C that is 5°C higher than the temperature n°C, and Max{(R n+5 / R n ) / 5} was confirmed within the temperature range of 25℃ to 135℃ (R n+5 / R n ) / 5 is the maximum value.

[0033] ΔR1 in Equation 1 is measured for a coin cell to which the polymer layer is applied, and the specific method is described in "7. Measurement of Maximum Resistance Change Rate (DC Resistance)" in the Examples. In the method for determining ΔR1, the initial temperature is 25°C and the final temperature is 135°C. The DC resistance is measured at each temperature while increasing the temperature by 5°C from the initial temperature of 25°C. n+5 and R n For example, if n is 90, then R 95 / R 90 is the ratio of the DC resistance at 95°C to the DC resistance at 90°C. For example, if ΔR1 is 100 Ω·cm / °C or greater at any temperature within the temperature range of 25°C to 135°C, this means that the resistance of the polymer layer, electrode current collector, or electrode increases relatively rapidly at any temperature within the temperature range.

[0034] The lower limit of ΔR1 may be about 40, 45, 50, 55, 60, 65, 70, 75, 80, 90, 100, 150, 200, 250, 300, 350, or 400, and the upper limit may be about 1,000, 950, 900, 850, 800, 750, 700, 650, 600, 550, 500, 450, 400, 350, 300, 250, 200, 150, or 100. The unit of ΔR1 is Ω·cm / °C. ΔR1 may be within a range that is equal to or exceeds any one of the lower limits mentioned above; or it may be within a range that is equal to or exceeds any one of the upper limits mentioned above while being equal to or less than any one of the upper limits mentioned above.

[0035] Due to these characteristics, the electrode to which the polymer layer is applied can ensure the stability of secondary batteries under abnormal conditions.

[0036] The temperature at which ΔR1 is confirmed, i.e., R n The lower limit of the temperature may be about 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 about 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 within a range that is equal to or less than any of the upper limits mentioned above; or equal to or greater than any of the lower limits mentioned above; or equal to or less than any of the upper limits but equal to or greater than any of the lower limits mentioned above. The temperature is adjusted to a temperature at which an abnormal condition occurs or there is a risk of an abnormal condition occurring. When a polymer layer exhibiting the above properties is applied, an electrode, an electrode assembly, or a secondary battery can maintain stable performance even when stored at a relatively high temperature under normal conditions and when charged and discharged at a high temperature, and can ensure stability under abnormal conditions.

[0037] The polymer layer, electrode current collector, or electrode may exhibit a characteristic in which ΔR2 in the following formula 2 is within a predetermined range.

[0038] [Formula 2] △R2=Max{(R z+5 / R z ) / 5}

[0039] R in Equation 2 z is the AC impedance resistance at any temperature n°C within the range of 25°C to 135°C, and R z+5 is the AC impedance resistance at a temperature (n+5)°C that is 5°C higher than the temperature n°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.

[0040] ΔR2 in Equation 2 is measured for a coin cell to which the polymer layer is applied, and the specific method is described in "8. Measurement of Maximum Resistance Change Rate (AC Impedance)" in the Examples. In the method for determining ΔR2, the initial temperature is 25°C and the final temperature is 135°C. The temperature is increased by 5°C from the initial temperature of 25°C, and AC impedance resistance is measured at each temperature to determine the R z+5 and R z For example, if n is 90, then R 95 / R 90 is the ratio of the AC impedance resistance at 95°C to the AC impedance resistance at 90°C. For example, if ΔR2 is 10 Ω / °C or more at any temperature within the temperature range of 25°C to 135°C, this means that the resistance of the polymer layer, electrode current collector, or electrode increases relatively rapidly at any temperature within the temperature range.

[0041] The lower limit of ΔR2 may be about 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 33, 34, 36, 38, 40, 42, or 44, and the upper limit may be about 100, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 18, 16, 14, 12, or 10. The unit of ΔR2 is Ω / °C. ΔR2 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 may be in a range between less than or equal to any of the upper limits mentioned above and greater than or equal to any of the lower limits mentioned above.

[0042] Due to these characteristics, the electrode to which the polymer layer is applied can ensure the stability of secondary batteries under abnormal conditions.

[0043] The temperature at which ΔR2 in the above range is confirmed, i.e., R zThe lower limit of the temperature may be about 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 about 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 within a range that is less than or equal to any of the upper limits mentioned above; or greater than or equal to any of the lower limits mentioned above; or between a range that is less than or equal to any of the upper limits mentioned above and greater than or equal to any of the lower limits mentioned above. The temperature is adjusted to a temperature at which an abnormal condition occurs or there is a risk of an abnormal condition occurring. When a polymer layer exhibiting the above properties is applied, an electrode, an electrode assembly, or a secondary battery can maintain stable performance even when stored at a relatively high temperature under normal conditions and when charged and discharged at a high temperature, and can ensure stability under abnormal conditions.

[0044] The polymer layer, electrode current collector, or electrode may exhibit a characteristic in which the absolute value of ΔR3 in the following formula 3 is within a predetermined range.

[0045] [Formula 3] △R3=100×(C1-C2) / C1

[0046] In Equation 3, C1 is the discharge capacity at room temperature (approximately 25°C), and C2 is the discharge capacity after 60 hours of storage at 70°C. C1 and C2 in Equation 3 are the discharge capacities measured for the coin cell to which the polymer layer is applied, and the specific method for measuring this is summarized in "9. Discharge Capacity Measurement" in the Examples.

[0047] The upper limit of the absolute value of ΔR3 in Equation 3 may be about 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%, or 1%, and the lower limit may be about 0%, 0.5%, or 1.5%. The absolute value may be within a range equal to or less than any of the upper limits; or may be within a range equal to or less than any of the upper limits and equal to or greater than any of the lower limits. By ensuring these characteristics, the performance of the current collector, electrode, or secondary battery to which the polymer layer is applied can be stably maintained even when the current collector, electrode, or secondary battery is operated and stored under normal conditions at relatively high temperatures.

[0048] The polymer layer, electrode current collector, or electrode may exhibit a characteristic in which the absolute value of ΔR4 in the following formula 4 is within a predetermined range.

[0049] [Formula 4] △R4=100×(C1-C3) / C1

[0050] In Equation 4, C1 is the discharge capacity at room temperature (approximately 25°C), and C3 is the discharge capacity after 10 minutes of storage at 130°C. C1 and C3 in Equation 4 are the discharge capacities measured for the coin cell to which the polymer layer is applied, and the specific method for measuring this is summarized in "10. Discharge Capacity Measurement" in the Examples.

[0051] The lower limit of the absolute value of ΔR4 in Equation 4 may be approximately 15%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, or 68%, and the upper limit may be approximately 200%, 180%, 160%, 140%, 120%, 100%, 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 50%, 40%, 30%, or 20%. The absolute value range may be within a range that is equal to or greater than any of the lower limits stated above; or may be within a range that is equal to or less than any of the upper limits stated above, but is equal to or greater than any of the lower limits stated above.

[0052] Due to these characteristics, the electrode to which the polymer layer is applied can ensure the stability of secondary batteries under abnormal conditions.

[0053] Said properties can be achieved through the introduction of polymer layers as described below.

[0054] The current collector body may be any current collector body that is commonly used for positive or negative electrodes without any particular limitation.

[0055] The current collector body may be made of any material that is conductive and does not undergo chemical changes in a secondary battery or other applicable device. Examples of materials that can be used for the current collector body include copper, aluminum, stainless steel, nickel, titanium, and calcined carbon. Examples of materials that can be used for the current collector body include copper, aluminum, or stainless steel that has been surface-treated with carbon, nickel, titanium, or silver. The current collector body may be in the form of a film, sheet, foil, net, porous material, foam, or nonwoven fabric containing the above material. In some cases, the surface of the current collector body may be subjected to a known surface treatment to improve adhesion to other layers, such as a polymer layer or an active material layer.

[0056] Such a current collector body can usually have a thickness in the range of 3 μm to 500 μm, but is not limited to this.

[0057] The active material layer used to form the electrode may also be a layer that is commonly used.

[0058] The active material layer typically includes an electrode active material. The specific type of the electrode active material is not particularly limited, and materials that typically form a positive electrode or a negative electrode can be used.

[0059] For example, when the active material layer is a positive electrode active material layer, the electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; a lithium iron oxide such as LiFe3O4; or a compound having the chemical formula Li1+c1M n2 -c1O4(0≦c1≦0.33), LiM n Lithium manganese oxides such as O3, 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 the formula LiMnO2 (wherein 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); 2-c3 M c3 The lithium manganese composite oxide may be, but is not limited to, a lithium manganese composite oxide expressed as Li2Mn3MO8 (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 Li2Mn3MO8 (where M is at least one selected from the group consisting of Fe, Co, Ni, Cu, and Zn); 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 in the chemical formula is substituted with an alkaline earth metal ion.

[0060] When the active material layer is a negative electrode active material layer, as the electrode active material, a compound capable of reversible intercalation and deintercalation of lithium can be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy or Al alloy; SiO a (0 < a < 2), metal oxides such as SnO2, vanadium oxide, and lithium vanadium oxide that can be doped and undoped with lithium; or composites containing the metallic compound and the carbonaceous material such as Si-C composite or Sn-C composite, etc. can be mentioned, and any one or a mixture of two or more of these can be used.

[0061] 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 etc. may be used. Representative low-crystalline carbons are soft carbon and hard carbon, and representative high-crystalline carbons are amorphous, plate-like, flaky, spherical or fibrous natural graphite or artificial graphite, kish graphite, pyrolytic carbon, mesophase pitch based carbon fiber, mesocarbon microbeads, mesophase pitches, and high-temperature calcined carbons such as petroleum or coal tar pitch derived cokes.

[0062] The electrode active material may be contained within the active material layer in the range of about 80 wt% to 99.5 wt% or 88 wt% to 99 wt% based on the total weight of the active material layer, but the ratio can be changed depending on the use and design of the electrode, etc.

[0063] The active material layer may further include a binder. The binder serves to improve adhesion between active materials and 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 selected from the group consisting of sucrose, pullulan, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyarylate, etc. may be used.

[0064] The binder may be included in the active material layer in an amount of, for example, 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.

[0065] The active material layer may further include a conductive material, if necessary. Any known conductive material may be used as the conductive material, as long as it is conductive and does not induce chemical changes in the secondary battery. Examples of such conductive materials include graphite, such as natural graphite or artificial graphite; carbon black, such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers, such as carbon fiber and metal fiber; 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.

[0066] The conductive material may be contained in the active material layer 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, but is not limited thereto.

[0067] The active material layer may optionally contain necessary known components in addition to the components described above.

[0068] The polymer layer on the current collector body may include a conductive polymer, which is a polymer that exhibits conductivity due to a conjugated polymer chain and / or doping, as is well known.

[0069] The conductive polymer may be a polymer having a so-called PTC (Positive Temperature Coefficient) characteristic, and an electrode exhibiting the above-mentioned characteristics may be effectively formed by controlling the tendency of the PTC effect and the oxidation potential of the polymer.

[0070] The polymer layer may contain only the conductive polymer, or may further contain the conductive polymer and other necessary additives. For example, the lower limit of the conductive polymer content in the polymer layer may be about 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, or 95 wt%, based on the total weight of the polymer layer, and the upper limit may be about 100 wt%, 95 wt%, 90 wt%, or 85 wt%, based on the total weight of the polymer layer. The content may range within a range that is less than or equal to any of the aforementioned upper limits; or greater than or equal to any of the aforementioned lower limits; or between a range that is less than or equal to any of the aforementioned upper limits and greater than or equal to any of the aforementioned lower limits.

[0071] The oxidation potential of the conductive polymer or polymer layer can be adjusted according to the purpose. The method for measuring the oxidation potential is summarized in the Examples of this specification. The oxidation potential is determined by the amount of lithium and lithium ions (Li / Li + The method for measuring the oxidation potential is summarized in "4. Method for measuring oxidation potential" in the Examples of this specification.

[0072] The lower limit of the oxidation potential may be about 2 V, 2.1 V, 2.2 V, 2.3 V, 2.4 V, 2.5 V, 2.6 V, 2.7 V, 2.8 V, 2.9 V, 3 V, 3.1 V, 3.2 V, 3.3 V, 3.4 V, 3.5 V, 3.6 V, or 3.7 V, and the upper limit may be about 5 V, 4.9 V, 4.8 V, 4.7 V, 4.6 V, 4.5 V, 4.4 V, 4.3 V, 4.2 V, 4.1 V, 4.0 V, 3.9 V, 3.8 V, 3.7 V, 3.6 V, or 3.5 V. The oxidation potential may be in a range that is less than or equal to any of the upper limits mentioned above; or in a range that is greater than or equal to any of the lower limits mentioned above; or in a range that is less than or equal to any of the upper limits mentioned above but greater than or equal to any of the lower limits mentioned above. By using a conductive polymer having such an oxidation potential, a polymer layer and an electrode having desired properties can be effectively formed.

[0073] The conductive polymer may have a weight-average molecular weight within a predetermined range, and the lower limit of the weight-average molecular weight of the conductive polymer may be 30,000 g / mol, 35,000 g / mol, 40,000 g / mol, 45,000 g / mol, 50,000 g / mol, 55,000 g / mol, 60,000 g / mol, 65,000 g / mol, 70,000 g / mol, 75,000 g / mol, 80,000 g / mol, 85,000 g / mol, 90,000 g / mol, 95,000 g / mol, 100,000 g / mol, 105,000 g / mol, 110,000 g / mol, 115,000 g / mol, 120,000 g / mol, 125,000 g / mol, 130,000 g / mol, or 140,000 g / mol. The upper limit may be about 1,000,000 g / mol, 950,000 g / mol, 900,000 g / mol, 850,000 g / mol, 800,000 g / mol, 750,000 g / mol, 700,000 g / mol, 650,000 g / mol, 600,000 g / mol, 550,000 g / mol, 500,000 g / mol, 450,000 g / mol, 400,000 g / mol, 350,000 g / mol, 300,000 g / mol, 250,000 g / mol, 200,000 g / mol, 150,000 g / mol, or 110,000 g / mol. The weight-average molecular weight may be within a range of less than or equal to any of the upper limits mentioned above; or within a range of more than or equal to any of the lower limits mentioned above; or within a range of less than or equal to any of the upper limits mentioned above and more than or equal to any of the lower limits mentioned above. By using a conductive polymer having such a weight-average molecular weight, a polymer layer and an electrode having desired properties can be effectively formed.

[0074] The molecular weight distribution of the conductive polymer, 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 about 2, 2.5, 3, 3.5, 4, or 4.5, and the upper limit may be about 8, 7.5, 7, 6.5, 6, 5.5, or 5. The molecular weight distribution may be within a range equal to or less than any of the above upper limits; or within a range equal to or greater than any of the above lower limits; or within a range equal to or less than any of the above upper limits but equal to or greater than any of the above lower limits. By using a conductive polymer having such a molecular weight distribution, it is possible to effectively form a polymer layer, an electrode current collector, and an electrode with desired properties.

[0075] The weight average molecular weight and molecular weight distribution can be measured by the method described in "2. GPC (Gel Permeation Chromatograph)" in the Examples of this specification.

[0076] The conductive polymer may be a thiophene polymer. As used herein, the term "polythiophene" refers to a polymer containing a certain amount of thiophene monomer units. By using a thiophene polymer as the conductive polymer, a desired polymer layer can be efficiently formed.

[0077] The lower limit of the ratio of thiophene units in the thiophene polymer may be about 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 about 100 mol%, 95 mol%, or 90 mol%. The ratio of the thiophene units may be within a range that is equal to or greater than any of the above-mentioned lower limits; or it may be within a range that is equal to or less than any of the above-mentioned upper limits, but is equal to or greater than any of the above-mentioned lower limits.

[0078] As used herein, the term "thiophene unit" refers to a unit formed by polymerizing a thiophene-based monomer, and the thiophene-based monomer refers to a monomer containing a thiophene skeleton.

[0079] To achieve appropriate properties, the conductive polymer may be a conductive polymer containing a thiophene unit having a long-chain hydrocarbon group (hereinafter referred to as a first thiophene unit) and a thiophene unit having a short-chain hydrocarbon group (hereinafter referred to as a second thiophene unit). Such a conductive polymer is a conductive copolymer.

[0080] As used herein, the term "long chain hydrocarbon functional group" refers to a monovalent hydrocarbon group having a carbon number equal to or greater than a certain level, or a monovalent functional group containing a monovalent hydrocarbon group having a carbon number equal to or greater than said certain level.

[0081] As used herein, the term "short chain hydrocarbon functional group" refers to a monovalent hydrocarbon group having a carbon number up to a certain level or a monovalent functional group containing a monovalent hydrocarbon group having a carbon number up to said certain level.

[0082] The lower limit of the number of carbon atoms in the long-chain hydrocarbon group may be about 10, 11, or 12, and the upper limit may be about 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, or 10. The number of carbon atoms in the long-chain hydrocarbon group may be within a range that is equal to or greater than any of the above-mentioned lower limits; or it may be within a range that is equal to or less than any of the above-mentioned upper limits, but is equal to or greater than any of the above-mentioned lower limits.

[0083] The lower limit of the number of carbon atoms in the short-chain hydrocarbon group may be about 3, 4, 5, 6, 7, or 8, and the upper limit may be about 9, 8, 7, or 6. The number of carbon atoms in the short-chain hydrocarbon group may be within a range equal to or less than any of the above upper limits; or may be within a range equal to or less than any of the above upper limits but equal to or greater than any of the above lower limits.

[0084] The carbon number may be the total number of carbon atoms present in the long-chain and short-chain hydrocarbon functional groups, or the number of carbon atoms in the linear hydrocarbon chains contained in the functional groups. That is, the monovalent hydrocarbon groups present in the long-chain and short-chain hydrocarbon functional groups may have a linear or branched structure, and even if they have a branched structure, the number of carbon atoms constituting the longest linear chain in the branched structure may be within the above range. For example, if the branched chain structure is a 2-ethylhexyl group, the number of carbon atoms constituting the longest linear chain may be 6.

[0085] Examples of the long-chain and short-chain hydrocarbon functional groups include one or more selected from the group consisting of alkyl groups, alkenyl groups, alkynyl groups, alkoxy groups, alkylcarbonyl groups, and alkylcarbonyloxy groups. Suitable examples of the long-chain and short-chain hydrocarbon functional groups include alkyl groups and / or alkoxy groups.

[0086] The number of carbon atoms present in the alkyl group, alkenyl group, alkynyl group, alkoxy group, alkyl group of the alkylcarbonyl group, and alkyl group of the alkylcarbonyloxy group may be within the range of the number of carbon atoms present in the long-chain or short-chain hydrocarbon functional group (i.e., the number of carbon atoms in the monovalent hydrocarbon group).

[0087] For example, the alkyl group, alkenyl group, alkynyl group, alkoxy group, alkyl group of the alkylcarbonyl group, and alkyl group of the alkylcarbonyloxy group may have a linear or branched chain structure, and when the alkyl group is branched, the number of carbon atoms constituting the longest linear chain in the branched chain structure may be within the above range.

[0088] The hydrocarbon functional groups, alkyl, alkenyl, alkynyl, alkoxy, alkylcarbonyl, and alkylcarbonyloxy, may be optionally substituted with one or more substituents.

[0089] In the conductive copolymer, the lower limit of the ratio of the total molar number of the first and second thiophene units based on the total polymerized units of the conductive copolymer may be about 80 mol%, 82 mol%, 84 mol%, 86 mol%, or 88 mol%, and the upper limit may be about 99 mol%, 97 mol%, 95 mol%, 93 mol%, 91 mol%, or 90 mol%. The ratio may be within a range equal to or less than any of the above upper limits; or equal to or greater than any of the above lower limits; or may be within a range equal to or less than any of the above upper limits but equal to or greater than any of the above lower limits.

[0090] The ratio (M2 / M1) of the moles of the second thiophene units (M2) to the moles of the first thiophene units (M1) in the conductive copolymer may have a lower limit of about 0.01, 0.05, 0.1, 0.5, 1, 1.5, or 2, and an upper limit of about 100, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.8, 0.7, 0.6, or 0.55. The ratio may be in a range that is less than or equal to any of the aforementioned upper limits; or in a range that is greater than or equal to any of the aforementioned lower limits; or in a range that is less than or equal to any of the aforementioned upper limits but greater than or equal to any of the aforementioned lower limits.

[0091] Under such a ratio, the conductive copolymer or the polymer layer exhibits an appropriate PTC (Positive Temperature Coefficient) effect, and its surface properties are controlled to ensure excellent adhesion to the electrode or electrode current collector.

[0092] The hydrocarbon group is a functional group that can impart appropriate mobility to the conductive polymer itself or to the polymerization process of the conductive polymer. Such functional groups impart appropriate mobility to the monomer mixture and diffuse within the monomer mixture, enabling efficient polymerization. Furthermore, conductive polymers having such functional groups can ensure stable and uniform formation of a polymer layer between the current collector body and the active material layer through appropriate mobility.

[0093] In addition, the hydrocarbon groups may be properly oriented during the drying or annealing process (heat treatment process) applied during the formation of the polymer layer to impart PTC effect and oxidation potential characteristics suited to the copolymer.

[0094] When a certain amount of thermal energy is applied, the hydrocarbon group vibrates due to the heat. This vibration (thermal vibration) promotes the dedoping of anions bound to the copolymer, thereby inducing an increase in resistance. The temperature at which the thermal vibration occurs can be controlled by the length and / or amount of the hydrocarbon 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 therefore, the long chain can induce a resistance increase effect at a relatively low temperature. Therefore, the desired PTC effect can be achieved by controlling the length and / or ratio of the long-chain hydrocarbon group.

[0095] In one example, the first thiophene unit may be represented by the following Formula 1:

[0096] [ka]

[0097] In Formula 1, R1 and R2 may each independently be hydrogen or the long-chain hydrocarbon group, and in this case, at least one of R1 and R2 may be the long-chain hydrocarbon group.

[0098] In another example, R1 and R2 may be linked to each other to form a divalent functional group of the following formula 2:

[0099] [ka]

[0100] In Chemical Formula 2, L1 and L2 are each independently a single bond, an alkylene group, or an alkylidene group, and R3 and R4 are each independently hydrogen or the long-chain hydrocarbon group, provided that at least one of R3 and R4 may be the long-chain hydrocarbon group.

[0101] The specific details of the long chain hydrocarbon group are as described above.

[0102] As used herein, the term "alkylene group" refers to a divalent functional group formed by removing hydrogen atoms from two different carbon atoms in an alkane, and the term "alkylidene group" refers to a divalent functional group formed by removing two hydrogen atoms from one carbon atom in an alkane.

[0103] As used herein, the term "alkylene group" refers to an alkylene group having 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms, unless otherwise specified. The alkylene group may be linear, branched, or cyclic, and may be optionally substituted with one or more substituents.

[0104] As used herein, unless otherwise specified, the term "alkylidene group" may refer to an alkylidene group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. The alkylidene group may be linear, branched, or cyclic, and may be optionally substituted with one or more substituents.

[0105] Meanwhile, the second thiophene unit may be represented by the following Chemical Formula 3:

[0106] [ka]

[0107] In Chemical Formula 3, R5 and R6 may each independently be hydrogen or the short chain hydrocarbon group, and in this case, at least one of R5 and R6 may be the short chain hydrocarbon group.

[0108] In another example, R5 and R6 may be linked to each other to form a divalent functional group of Formula 4 below.

[0109] [ka]

[0110] In Chemical Formula 4, L3 and L4 are each independently a single bond, an alkylene group, or an alkylidene group, and R7 and R8 are each independently a hydrogen atom or the short-chain hydrocarbon group, provided that at least one of R7 and R8 is the short-chain hydrocarbon group.

[0111] The specific details of the short chain hydrocarbon group are as described above.

[0112] The specific details of the alkylene group and alkylidene group in Chemical Formula 4 are the same as those described in Chemical Formulas 2 and 3 above.

[0113] The conductive polymer may further include necessary units in addition to the above units.

[0114] For example, the conductive polymer may further include a thiophene unit having a polar functional group (hereinafter, referred to as a third thiophene unit).

[0115] As used herein, 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 polar functional groups include, but are not limited to, a carboxyl group, a hydroxyl group, an amino group, a cyano group, a nitro group, an ether group, or a functional group represented by the following formula 5:

[0116] [ka]

[0117] In Chemical Formula 5, 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 an arbitrary number.

[0118] In Chemical Formula 5, L4 being a single bond means that L4 does not exist and the oxygen atom between L4 and L3 is linked to the backbone of a monomer or polymer.

[0119] Specific examples of the alkylene group or alkylidene group in Chemical Formula 5 are the same as those in Chemical Formulas 2 to 4.

[0120] The alkyl group of R5 in Chemical Formula 5 may be, for example, 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 linear, branched, or cyclic, and may be suitably linear or branched.

[0121] In Chemical Formula 5, the lower limit of n may be about 1, 2, 3, or 4, and the upper limit may be about 10, 9, 8, 7, 6, 5, 4, or 3. n may be in a range that is less than or equal to any of the upper limits mentioned above; or in a range that is greater than or equal to any of the lower limits mentioned above; or in a range that is less than or equal to any of the upper limits mentioned above but greater than or equal to any of the lower limits mentioned above.

[0122] By applying the polar functional group, a polymer layer including a conductive polymer can be bonded to other layers with appropriate bonding strength, and such a conductive polymer layer can be uniformly formed to efficiently achieve the intended protective function.

[0123] The third thiophene unit may be represented, for example, by the following Chemical Formula 6:

[0124] [ka]

[0125] R in Chemical Formula 6 10 and R 11 may each independently be hydrogen or the polar functional group, in which case the R 10 and R 11 At least one of the groups is the polar functional group.

[0126] In another example, R 10 and R 11 can be linked together to form a divalent functional group of the following formula 7:

[0127] [ka]

[0128] In Chemical Formula 7, L7 and L8 are each independently a single bond, an alkylene group, or an alkylidene group; R 12 and R 13are each independently hydrogen or a polar functional group, but R 12 and R 13 At least one of the groups is the polar functional group.

[0129] The polar functional group is as described above.

[0130] Specific details of the alkylene group or alkylidene group are as described in Chemical Formulas 2 to 5 above.

[0131] When the third thiophene unit is present in the conductive copolymer, the third thiophene unit may be present such that the total number of moles of the first and second thiophene units is within a predetermined range per mole of the third thiophene unit.

[0132] For example, the lower limit of the total number of moles of the first and second thiophene units per mole of the third thiophene unit may be about 1 mole, 2 moles, 3 moles, 4 moles, 5 moles, 6 moles, 8 moles, or 8.5 moles, and the upper limit may be about 500 moles, 450 moles, 400 moles, 350 moles, 300 moles, 250 moles, 200 moles, 150 moles, 100 moles, 95 moles, 90 moles, 85 moles, 80 moles, 75 moles, 70 moles, 65 moles, 60 moles, 55 moles, 50 moles, 45 moles, 40 moles, 35 moles, 30 moles, 25 moles, 20 moles, 15 moles, 10 moles, 9.5 moles, or 9 moles. The ratio may be in a range that is less than or equal to any of the aforementioned upper limits; or greater than or equal to any of the aforementioned lower limits; or less than or equal to any of the aforementioned upper limits but greater than or equal to any of the aforementioned lower limits.

[0133] When the first to third thiophene units are present in the conductive polymer, the lower limit of the ratio of the total number of moles of the thiophene units (the total number of moles of the first to third thiophene units) to the number of moles of all monomer units in the conductive polymer may be about 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 about 100 mol%, 95 mol%, or 90 mol%. The ratio may be within a range that is equal to or less than any of the above upper limits; or equal to or greater than any of the above lower limits; or within a range that is equal to or less than any of the above upper limits but equal to or greater than any of the above lower limits.

[0134] The conductive polymer may further contain other polymer units as long as it contains the above-mentioned units in the above-mentioned proportions.

[0135] The polymer layer includes the conductive polymer and can therefore exhibit the above-described properties.

[0136] The polymer layer may also contain any additional components as long as it contains the conductive polymer.

[0137] The thickness of the polymer layer can be appropriately controlled depending on the purpose. For example, the lower limit of the thickness can be about 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 can be about 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 can be within a range that is equal to or less than any of the upper limits mentioned above; or equal to or greater than any of the lower limits mentioned above; or equal to or less than any of the upper limits mentioned above but equal to or greater than any of the lower limits mentioned above.

[0138] The thickness can be measured by the method described in "3. Thickness Measurement" in the Examples section of this specification.

[0139] The polymer layer exhibits the above-mentioned properties, thereby exhibiting suitable surface properties, and therefore, excellent adhesive strength can be ensured between layers in an electrode or a current collector for an electrode.

[0140] For example, the surface energy of the polymer layer in the electrode current collector may be controlled within a predetermined range. For example, the lower limit of the surface energy may be about 25 mN / m, 30 mN / m, 35 mN / m, 40 mN / m, or 45 mN / m, and the upper limit may be about 100 mN / m, 95 mN / m, 90 mN / m, 85 mN / m, 80 mN / m, 75 mN / m, 70 mN / m, 65 mN / m, 60 mN / m, 55 mN / m, 50 mN / m, 45 mN / m, 40 mN / m, or 35 mN / m. The surface energy may be within a range equal to or less than any of the upper limits; or within a range equal to or greater than any of the lower limits; or within a range equal to or less than any of the upper limits but equal to or greater than any of the lower limits.

[0141] The surface energy can be measured by the method described in "12. Surface energy evaluation method" in the Examples section of this specification.

[0142] The present specification also discloses a method for producing the electrode current collector or electrode.

[0143] The method for manufacturing a current collector for an electrode of the present invention may include forming the polymer layer on the current collector body, and the method for manufacturing the electrode may include forming the active material layer on the polymer layer.

[0144] There is no particular limitation on the method for forming the polymer layer on the current collector body. For example, the polymer layer may be formed by preparing a coating solution by diluting the conductive polymer and, if necessary, other additives in an appropriate solvent, coating the coating solution on the current collector, and then drying the coating solution.

[0145] In another example, the polymer layer may be formed by directly polymerizing a monomer that forms the conductive polymer on the current collector body.

[0146] The preparation and coating method of the coating composition for forming the polymer layer are not particularly limited, and known coating methods can be used. Furthermore, the method for polymerizing the conductive polymer is also not particularly limited, and known methods can be used. For example, methods using oxidative polymerization or radical reaction are typically known for preparing polythiophene, and these methods can also be used in the process of forming the conductive polymer in the present invention.

[0147] The prepared coating composition can be used to form a polymer layer on the current collector body. This process typically includes coating the coating composition on the current collector body and heat-treating the coated coating composition. During this process, the properties of the polymer layer can be controlled by the conditions of the heat treatment.

[0148] For example, the temperature T of the heat treatment and / or the time H of the heat treatment may be adjusted.

[0149] For example, the lower limit of the temperature T may be about 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, or 140°C, and the upper limit may be about 300°C, 295°C, 290°C, 285°C, 280°C, 275°C, 270°C, 285°C, 280°C, 295°C, 29 ... The temperature may be about 65°C, 260°C, 255°C, 250°C, 245°C, 240°C, 235°C, 230°C, 225°C, 220°C, 215°C, 210°C, 205°C, 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, or 130°C. The temperature may be within a range equal to or less than any of the upper limits mentioned above; or equal to or greater than any of the lower limits mentioned above; or within a range equal to or less than any of the upper limits mentioned above but equal to or greater than any of the lower limits mentioned above. Within this range, the alignment state of the hydrocarbon groups of the conductive copolymer can be appropriately controlled, thereby ensuring the desired properties.

[0150] The product of the heat treatment temperature T and the time H (T×H) can be adjusted to achieve the desired result. For example, the lower limit of the product of the heat treatment temperature T and the time H (T×H) can be 0.01° C. / hour, 0.05° C. / hour, 0.1° C. / hour, 0.2° C. / hour, 0.3° C. / hour, 0.5° C. / hour, 1° C. / hour, 5° C. / hour, 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, or 130° C. / hour. The 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°C.hour, 20,000°C.hour, 15,000°C.hour, 10 000℃.hour, 9500℃.hour, 9000℃.hour, 8500℃.hour, 8000℃.hour, 7500℃.hour, 7000℃.hour, 6500℃.hour, 6000℃.hour, 5500℃.hour, 5000℃.ho ur, 4500℃.hour, 4000℃.hour, 3500℃.hour, 3000℃.hour, 2500℃.hour, 2000℃.hour, 1500℃.hour, 1400℃.hour, 1300℃.hour, 1200℃.hour, 1100℃ .hour, 1000℃.hour, 900℃.hour, 800℃.hour, 700℃.hour, 600℃.hour, 500℃.hour, 400℃.hour, 300℃.hour, 200℃.hour, 100℃.hour, 90℃.hour, 8 It may be about 0°C.hour, 70°C.hour, 60°C.hour, 50°C.hour, 45°C.hour, 40°C.hour, 35°C.hour, 30°C.hour, 25°C.hour, 20°C.hour, 15°C.hour or 10°C.hour.The product (T × H) may be within a range of less than or equal to any of the upper limits set forth above; or within a range of greater than or equal to any of the lower limits set forth above; or within a range of less than or equal to any of the upper limits set forth above but greater than or equal to any of the lower limits set forth above. Within such a range, the alignment state of the hydrocarbon groups of the conductive copolymer can be appropriately controlled, thereby ensuring the desired properties.

[0151] To more effectively secure the desired properties, the heat treatment can be carried out in two stages.

[0152] For example, the heat treatment may include a step of first heat treating the coating composition at a first temperature T1 for a first time H1 and a step of second heat treating the coating composition at a second temperature T2 for a second time H2, wherein the temperatures T1 and T2 are different from each other and / or the times H1 and H2 are different from each other.

[0153] For example, the lower limit of the temperature T1 may be about 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, or 140°C, and the upper limit may be about 300°C, 295°C, 290°C, 285°C, 280°C, 275°C, The temperature may be about 270°C, 265°C, 260°C, 255°C, 250°C, 245°C, 240°C, 235°C, 230°C, 225°C, 220°C, 215°C, 210°C, 205°C, 200°C, 195°C, 190°C, 185°C, 180°C, 175°C, 170°C, 165°C, 160°C, 155°C, 150°C, 145°C, or 140°C. The temperature may be within a range equal to or less than any of the upper limits mentioned above; or equal to or greater than any of the lower limits mentioned above; or within a range equal to or less than any of the upper limits mentioned above but equal to or greater than any of the lower limits mentioned above. Within this range, the alignment state of the hydrocarbon groups of the conductive copolymer can be appropriately controlled, thereby ensuring the desired properties.

[0154] For example, the lower limit of the product of the temperature T1 and the time H1 of the primary heat treatment (T1 x H1) may be about 0.01°C / hour, 0.05°C / hour, 0.1°C / hour, 0.2°C / hour, 0.3°C / hour, 1°C / hour, 2°C / hour, 3°C / hour, 4°C / hour, 5°C / hour, 6°C / hour, 7°C / hour, 8°C / hour, or 9°C / hour, and the upper limit may be about 1000°C / hour, 900°C / hour, 800°C / hour, or 1000°C / hour. The product (T1 × H1) may be about 1 / 2, 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, 40°C / hour, 35°C / hour, 30°C / hour, 25°C / hour, 20°C / hour, 15°C / hour, or 10°C / hour. The product (T1 × H1) may be within a range equal to or less than any of the upper limits mentioned above; or within a range equal to or greater than any of the lower limits mentioned above; or within a range equal to or less than any of the upper limits mentioned above but equal to or greater than any of the lower limits mentioned above. Within these ranges, the alignment state of the hydrocarbon groups of the conductive copolymer can be appropriately controlled, thereby ensuring the desired properties.

[0155] For example, the lower limit of the heat treatment temperature T2 of the second heat treatment may be about 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, or 130°C, and the upper limit may be about 300°C, 295°C, 290°C, 285°C, 280°C, 275°C, 270°C, 285°C, 280°C, 295°C, 29 ... The temperature may be about 65°C, 260°C, 255°C, 250°C, 245°C, 240°C, 235°C, 230°C, 225°C, 220°C, 215°C, 210°C, 205°C, 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, or 130°C. The temperature may be within a range equal to or less than any of the upper limits mentioned above; or equal to or greater than any of the lower limits mentioned above; or within a range equal to or less than any of the upper limits mentioned above but equal to or greater than any of the lower limits mentioned above. Within this range, the alignment state of the hydrocarbon groups of the conductive copolymer can be appropriately controlled, thereby ensuring the desired properties.

[0156] The product of the second heat treatment temperature T2 and the time H2 (T2×H2) can be adjusted. For example, the lower limit of the product of the heat treatment temperature T and time H (T2 × H2) may be about 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, or 130°C / hour, and the upper limit may be about 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, 180°C / hour, 160°C / hour, 150°C / hour, 145°C / hour, 140°C / hour, 135°C / hour, or 130°C / hour. The product (T2 × H2) may be within a range of less than or equal to any of the upper limits mentioned above; or may be within a range of greater than or equal to any of the lower limits mentioned above; or may be within a range of less than or equal to any of the upper limits mentioned above but greater than or equal to any of the lower limits mentioned above. Within such a range, the alignment state of the hydrocarbon groups of the conductive copolymer can be appropriately controlled, thereby ensuring the desired properties.

[0157] In this case, the lower limit of the ratio T1 / T2 of the temperature T1 of the first heat treatment to the temperature T2 of the second heat treatment may be about 0.1, 0.3, 0.5, 0.7, 0.9, 0.95, 1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, or 1.07, and the upper limit may be about 10, 9, 8, 7, 6, 5, 4, 3, 2, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, or 1.1. The ratio T1 / T2 may be within a range equal to or less than any of the above upper limits; or within a range equal to or greater than any of the above lower limits; or within a range equal to or less than any of the above upper limits but equal to or greater than any of the above lower limits. Within this range, the alignment state of the hydrocarbon groups of the conductive copolymer can be appropriately controlled, thereby ensuring the desired properties.

[0158] In this case, the lower limit of the ratio H2 / H1 of the time H1 for the first heat treatment to the time H2 for the second heat treatment may be about 0.5, 1, 3, 5, 7, 9, 10, 11, 12, 13, 14, 14.5, or 15, and the upper limit may be about 100, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 19, 18, 17, 16, 15.5, or 15. The ratio H2 / H1 may be within a range equal to or less than any of the above upper limits; or within a range equal to or greater than any of the above lower limits; or within a range equal to or less than any of the above upper limits but equal to or greater than any of the above lower limits. Within this range, the alignment state of the hydrocarbon groups of the conductive copolymer can be appropriately controlled, thereby ensuring the desired properties.

[0159] In the manufacturing process, a post-process such as an appropriate drying process may be additionally performed following the coating and / or polymerization process.

[0160] There is no particular limitation on the method for forming the active material layer on the polymer layer. Typically, the active material layer is formed by coating a slurry containing the electrode active material, binder, and conductive material on a current collector (polymer layer), drying the coating, and then rolling the coating. Such a known method can be equally applied to the present invention.

[0161] Through the above process, the surface properties of the polymer layer are controlled, thereby ensuring excellent adhesive strength.

[0162] For example, the lower limit of the adhesive strength of the active material layer to the polymer layer or the current collector layer in the electrode may be about 40 gf / 20 mm, 50 gf / 20 mm, 60 gf / 20 mm, 70 gf / 20 mm, 80 gf / 20 mm, 90 gf / 20 mm, 100 gf / 20 mm, 110 gf / 20 mm, 120 gf / 20 mm, 130 gf / 20 mm, or 140 gf / 20 mm, and the upper limit thereof may be about 500 gf / 20 mm. The adhesive strength may be about 20 mm, 450 gf / 20 mm, 400 gf / 20 mm, 350 gf / 20 mm, 300 gf / 20 mm, 250 gf / 20 mm, 200 gf / 20 mm, 150 gf / 20 mm, 140 gf / 20 mm, 130 gf / 20 mm, 120 gf / 20 mm, 110 gf / 20 mm, 100 gf / 20 mm, 90 gf / 20 mm, 80 gf / 20 mm, or 70 gf / 20 mm. The adhesive strength may be within a range that is equal to or greater than any of the lower limits mentioned above; or may be within a range that is equal to or less than any of the upper limits mentioned above, but is equal to or greater than any of the lower limits mentioned above.

[0163] The adhesive strength is summarized in "11. Method for evaluating adhesive strength" in the Examples section of this specification.

[0164] The adhesive strength of the active material layer to the polymer layer or current collector layer means an adhesive strength that does not cause a phenomenon in which all or part of the active material layer is peeled off from the polymer layer, a phenomenon in which all or part of the polymer layer is peeled off from the current collector layer, or other interfacial breakdown phenomena, when measured using the adhesive strength evaluation method described in the Examples (Adhesion Strength B in the evaluation method in the Examples).

[0165] The present invention also relates to an electrode assembly or an electrochemical device, such as a secondary battery, including the electrode.

[0166] The electrochemical device may include the electrode as a positive electrode and / or a negative electrode. As long as the electrode of the present invention is used as a negative electrode and / or a positive electrode, other configurations and manufacturing methods of the electrochemical device are not particularly limited, and known methods may be applied. [Effects of the Invention]

[0167] This specification discloses a current collector for an electrode and uses thereof. The current collector for an electrode exhibits excellent electrical properties, including low resistance, under normal conditions, such as in a secondary battery, and can ensure stability through increased resistance under abnormal conditions. This specification also discloses uses of the current collector for an electrode. [Brief explanation of the drawings]

[0168] [Figure 1] 1 is a cross-sectional view of an exemplary electrode. [Figure 2] 1 shows the results of NMR analysis of the monomer of Production Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0169] Hereinafter, the current collectors disclosed in the present specification will be described in detail through examples and comparative examples, but the scope of the current collectors is not limited to the following examples.

[0170] 1.NMR analysis method 1 H-NMR analysis was performed at room temperature (approximately 25°C) using a Bruker UltraShield spectrometer (300 MHz) with a triple-resonance 5 mm probe. Samples were diluted to a concentration of approximately 10 mg / ml in NMR solvent (CDCl3), and chemical shifts were expressed in ppm.

[0171] 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 approximately 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 Empower 3 from Waters. The elution time of the sample was compared with the calibration curve to determine the weight average molecular weight (Mw) and the number average molecular weight (Mn) respectively, and the molecular weight distribution (PDI) was calculated using the ratio (Mw / Mn).

[0172] The measurement conditions for GPC are as follows.

[0173] <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)

[0174] 3. Thickness measurement The thickness of the polymer layer was measured by cross-sectioning the electrode or current collector using an ion milling device (Hitachi, IM5000) and then taking images with a scanning electron microscope (SEM) (JEOL, JSM-7200F). The conditions for cross-section formation using ion milling were set as follows: the device was in cross-section milling mode, the speed (reciprocation / min) was 3, the acceleration voltage was 6.0 kV, the discharge voltage was 15 kV, the current was 150 μA, and the time was 4 hours.

[0175] 4. Oxidation potential measurement method The oxidation potential was measured using the following method. A polymer layer of approximately 10 μm thick was formed using a conductive copolymer on an aluminum foil of approximately 15 μm thickness. The polymer (e.g., conductive copolymer) whose oxidation potential was to be measured was dispersed in a solvent (chloroform) at a concentration of approximately 2.0 wt% to prepare a coating solution. The coating solution was then bar-coated onto the aluminum foil and heated at 140°C for approximately 4 minutes, then again at 130°C for approximately 60 minutes to form the polymer layer. A separator and a lithium film were then laminated on the polymer layer to produce a laminate consisting of aluminum foil / polymer layer / separator / lithium film. The laminate was then punched into a circle with a diameter of approximately 1.4 cm. The punched-out circle and electrolyte were used to fabricate a coin cell (using a Welcos CR2032 coin cell kit). The separator used was a WL20C model manufactured by DoubleScope, the lithium film was a film with a thickness of about 100 μm, and the electrolyte used was a 1M LiPF6 solution (solvent: EC / DMC / EMC = 3 / 4 / 3 (mass ratio), EC: ethylene carbonate, DMC: dimethyl carbonate, EMC: ethylmethyl carbonate) manufactured by Enchem.

[0176] The oxidation potential of the coin cell was measured using an electrochemical potentiostat (Princeton Applied Research, PARASTAT-MC) at 25°C for lithium and lithium ions (Li / Li + The oxidation potential was measured using a voltage of 1.5 V to 5.5 V at a scan rate of 0.17 mV / sec to 0.5 mV / sec, and the oxidation potential was measured by CV (Cyclic Voltammetry).

[0177] 5.DC resistance measurement method DC resistance was evaluated using the same coin cell as that used for the 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 multi-tester (FLUKE-87-5).

[0178] 6.Interface resistance (AC impedance resistance) The interfacial resistance was evaluated by EIS (Electrochemical Impedance Spectroscopy) using the same coin cell used for the 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 in the high frequency region of the Nyquist plot obtained by EIS measurement at 50,000 Hz to 0.1 Hz was measured. The EIS measurement equipment used was an electrochemical measuring instrument (potentiostat) (Princeton Applied Research, PARASTAT-MC).

[0179] 7. Maximum resistance change rate measurement (DC resistance) The maximum resistance change rate ΔR1 is determined by the following formula 1.

[0180] [Formula 1] △R1=Max{(R n+5 / R n ) / 5}

[0181] The ΔR1 is measured in the following manner.

[0182] The coin cell for measuring DC resistance (the coin cell used in "5. DC Resistance Measurement Method" above) was placed in the center of a convection oven (JOTECH, OF3-05W), and the oven temperature was set to increase by 5°C per minute from an initial temperature of 25°C to a final temperature of 135°C. The coin cell was connected to a resistance measurement multimeter (Fluke digital multitester (FLUKE-87-5)) outside the oven to enable resistance measurement. The DC resistance was then measured at each temperature as the temperature increased as set. That is, the DC resistance is measured at 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, and 130°C. Each temperature is maintained for one minute according to the settings, and the DC resistance is measured after one minute has elapsed at that temperature. The DC resistance at each temperature is calculated by the R n The DC resistance at a temperature 5°C higher than the temperature in question is R n+5 Among the measured DC resistances, the DC resistances at 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃ and 125℃ are R n 21 values ​​of (R n+5 / R n ) / 5, the maximum value is calculated as Max{(R n+5 / R n ) / 5}(=△R1), and the maximum value of (R n+5 / R n The temperature n°C at ) / 5 is the On-Set temperature.

[0183] 8. Maximum resistance change rate measurement (AC impedance) The maximum resistance change rate ΔR2 is determined by the following formula 2.

[0184] [Formula 2] △R2=Max{(R z+5 / R z ) / 5}

[0185] The ΔR2 is measured in the following manner.

[0186] The coin cell for measuring AC impedance resistance (the coin cell used in "6. Interface Resistance (AC Impedance Resistance)" above) is placed in the center of a convection oven (JOTECH, OF3-05W), and the oven temperature is set to increase by 5°C per minute from an initial temperature of 25°C to a final temperature of 135°C. The coin cell is connected to a resistance meter (the meter used in "6. Interface Resistance (AC Impedance Resistance)" above) outside the oven to enable resistance measurement. The temperature is then increased as set, and the AC impedance resistance is measured at each temperature. That is, AC impedance resistance is measured at 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, and 130°C. Each temperature is maintained for one minute according to the settings, and the AC impedance resistance is measured after one minute has elapsed at that temperature.

[0187] The AC impedance resistance at each temperature is R z The AC impedance resistance at a temperature 5°C higher than the target temperature is R z+5 Among the measured AC impedance resistances, the AC impedance resistances at 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃ and 125℃ are R z 21 values ​​of (Rz+5 / R z ) / 5, the maximum value is calculated as Max{(R z+5 / R z ) / 5}(=△R2), and the maximum value of (R z+5 / R z The temperature z°C at ) / 5 is the On-Set temperature.

[0188] The AC impedance resistance was determined as the resistance obtained in a semicircle in the high frequency region of a Nyquist plot obtained by EIS measurement at 50,000 Hz to 0.1 Hz after applying a voltage of 4.3 V for 10 minutes.

[0189] 9. Discharge capacity measurement The discharge capacity to confirm the results of the following equation 3 was evaluated in the following manner.

[0190] [Formula 3] △R3=100×(C1-C2) / C1

[0191] In Equation 3, ΔR3 is the rate of change (%) of 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.

[0192] A coin cell (reference capacity: 200 mAh / g) for confirming the discharge capacity of Equation 3 was fabricated as follows. The coin cell was fabricated using a CR2032 standard coin cell kit (Welcos CR2032 coin cell kit). The electrode fabricated in the example or comparative example was used as the positive electrode, and a lithium film (thickness: 100 μm) was used as the negative electrode. The electrolyte was a carbonate-based electrolyte, a 1M LiPF solution (solvent: EC / DMC / EMC = 3 / 4 / 3 (mass ratio), EC: ethylene carbonate, DMC: dimethyl carbonate, EMC: ethylmethyl carbonate), and the separator was a polyethylene (PE) separator (WL20C model, manufactured by DoubleScope).

[0193] The coin cell was charged / discharged once at 25°C, and the capacity at 0.2C was defined as the discharge capacity C1 in Equation 3. One charge / discharge cycle refers to one cycle in which the cell was charged at a rate of 0.2C in a CC (Constant Current) / CV (Constant Voltage) mode with a charge cut-off voltage of 4.5V and a charge cut-off current of 1mA, and then discharged at a rate of 0.2C in a CC (Constant Current) mode with a discharge cut-off voltage of 3.0V. The discharge capacity after one charge / discharge cycle was used as the discharge capacity (C1) in Equation 3.

[0194] Immediately after fabricating the coin cell, C1 was determined by applying the measurement method, and then the coin cell was stored at 70°C for 60 hours, after which the discharge capacity was measured by the same method, and this value was used as C2 in Equation 3.

[0195] 10. Discharge capacity measurement The discharge capacity to confirm the results of the following equation 4 was evaluated in the following manner.

[0196] [Formula 4] △R4=100×(C1-C3) / C1

[0197] In Equation 4, ΔR4 is the rate of change (%) of discharge capacity, C1 is the discharge capacity at room temperature (approximately 25°C), and C3 is the discharge capacity after storing at 70°C for 60 hours and then again at 130°C for 10 minutes.

[0198] The coin cell used to confirm the discharge capacity of Equation 4 was the same as that used in "9. Discharge Capacity Measurement" above. C1 in Equation 4 was measured in the same manner as C1 in "9. Discharge Capacity Measurement" above.

[0199] The coin cell was then stored at 70°C for 60 hours and then at 130°C for 10 minutes, after which the discharge capacity C3 was calculated. C3 was calculated using the following method: charging at a rate of 0.5C using a CC (Constant Current) / CV (Constant Voltage) method with a charge cut-off voltage of 4.5V and a charge cut-off current of 1mA, and then discharging at a rate of 2C using a CC (Constant Current) method with a discharge cut-off voltage of 3.0V. This cycle was repeated 30 times, and the discharge capacity after 30 charge / discharge cycles was used as C3 in Equation 4. The 30 charge / discharge cycles were performed at 45°C.

[0200] 11.Adhesion strength evaluation method Adhesion strength was measured using a known active material layer adhesion measurement method using a TA analyzer (TAXTplusC). Test specimens were cut to a width of approximately 20 mm and the adhesion strength was evaluated. Test specimens were evaluated for the laminate (adhesion strength A) in which a polymer layer was formed on a current collector, and the final electrode (adhesion strength B) in which an active material layer was formed on the polymer layer in the following Examples and Comparative Examples. Specifically, adhesion strength A is the adhesion strength of the polymer layer to the current collector, and adhesion strength B is the adhesion strength of the active material layer to the polymer layer or current collector layer. The peel angle and peel speed during adhesion strength measurement were approximately 90° and 5 mm / sec, respectively. After measurement, the adhesion strength was defined as the average of the stabilized peaks.

[0201] 12.Surface energy evaluation method The surface energy was evaluated using a measuring instrument (DSA 100) manufactured by Kruss, and the contact angle was measured using water and diiodomethane, through which the surface energy was determined.

[0202] Preparation Example 1. Synthesis of Monomer (A) The monomer of the following formula A was synthesized in the following manner.

[0203] [ka]

[0204] In chemical formula A, n is 3.

[0205] 3g (26.28mmol, 1eq) of 3-methoxythiophene and 7.03g (39.42mmol, 1.5eq) of triethylene glycol monomethyl ether were dissolved in 150ml of toluene and mixed with 500mg of p-toluenesulfonic acid (p-TsOH) (2.63mmol, 0.1eq). The mixture was refluxed at 120°C under a nitrogen atmosphere, and the methanol produced by transetherification was removed using a 4A-type soxhlet extractor. The reaction mixture was refluxed for 24 hours, cooled to room temperature, quenched with water, extracted with ethyl acetate, washed with brine, and dried over magnesium sulfate (MgSO). The solvent was removed using a rotary evaporator, and the residue was purified by column chromatography eluting with methylene chloride / hexane (2:1) to obtain the target compound (monomer (A)). The NMR analysis result for the target compound (monomer (A)) is shown in Figure 2.

[0206] Example 1 Synthesis of polythiophene (A) 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride was dissolved in 150 ml of methylene chloride, and 1 g (3.94 mmol, 0.6 eq) of 3-dodecylthiophene, 0.33 g (1.97 mmol, 0.3 eq) of 3-hexylthiophene, and 0.16 g (0.66 mmol, 0.1 eq) of monomer (A) of Preparation Example 1 were added and polymerized at 30°C for 24 hours to prepare polythiophene (A).

[0207] The polymerization solution was poured into a membrane with a molecular weight cut-off (MWCO) of 5000 and then immersed in 200 ml of acetonitrile to remove unreacted iron(III) chloride, monomers, and low molecular weight oligomers. The residue precipitated inside the membrane was washed with methanol and dried at 60°C for 12 hours to produce polythiophene (A).

[0208] The polythiophene (A) had a weight average molecular weight (Mw) of 118,000 g / mol and a number average molecular weight (Mn) of 24,500 g / mol, respectively, and an oxidation potential of about 3.7 V.

[0209] Electrode manufacturing An aluminum foil with a thickness of approximately 15 μm was used as the current collector body. The prepared polythiophene (A) 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 body using a bar coating method, and then maintained at 140°C for approximately 4 minutes and then at 130°C for approximately 60 minutes to form the polymer layer (thickness: approximately 300 nm). An active material layer was formed on the polymer layer to prepare an electrode. 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 a thickness of approximately 90 μm using a doctor blade onto the polymer layer, drying at room temperature (approximately 25°C), and then further drying under vacuum at 120°C. The slurry was then rolled to a porosity of approximately 25%.

[0210] Example 2. Synthesis of polythiophene (B) 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride was dissolved in 150 ml of methylene chloride, and 0.5 g (1.97 mmol, 0.3 eq) of 3-dodecylthiophene, 0.66 g (3.94 mmol, 0.6 eq) of 3-hexylthiophene, and 0.16 g (0.66 mmol, 0.1 eq) of monomer (A) of Preparation Example 1 were added to the solution and polymerized at 30°C for 24 hours to prepare polythiophene (B).

[0211] The polymerization solution was poured into a membrane with a molecular weight cut-off (MWCO) of 5000 and then immersed in 200 ml of acetonitrile to remove unreacted iron(III) chloride monomer and low molecular weight oligomers. The residue precipitated inside the membrane was washed with methanol and dried at 60°C for 12 hours to produce polythiophene (B).

[0212] The polythiophene (B) had a weight average molecular weight (Mw) of 105,000 g / mol and a number average molecular weight (Mn) of 22,300 g / mol, respectively, and an oxidation potential of about 3.7V.

[0213] Electrode manufacturing An electrode was fabricated in the same manner as in Example 1, except that polythiophene (B) was used instead of polythiophene (A). At this time, the thickness of the polymer layer was about 300 nm.

[0214] Example 3. Synthesis of polythiophene (C) To a solution of 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride dissolved in 150 ml of methylene chloride, 0.88 g (3.94 mmol, 0.6 eq) of 3-decylthiophene, 0.33 g (1.97 mmol, 0.3 eq) of 3-hexylthiophene, and 0.16 g (0.66 mmol, 0.1 eq) of monomer (A) from Preparation Example 1 were added and polymerized at 30°C for 24 hours to produce polythiophene (C). The polymerization solution was placed in a permeation membrane with a molecular weight of cut-off (MWCO) of 5000 and immersed in 200 ml of acetonitrile to remove unreacted iron(III) chloride monomer and low molecular weight oligomers. The residue deposited inside the membrane was washed with methanol and dried at 60° C. for 12 hours to prepare polythiophene (C).

[0215] The polythiophene (C) had a weight-average molecular weight (Mw) of 110,500 g / mol and a number-average molecular weight (Mn) of 23,400 g / mol, respectively, and an oxidation potential of about 3.7 V.

[0216] Electrode manufacturing An electrode was fabricated in the same manner as in Example 1, except that polythiophene (C) was used instead of polythiophene (A). At this time, the thickness of the polymer layer was about 300 nm.

[0217] Example 4. Synthesis of polythiophene (D) To a solution of 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride dissolved in 150 ml of methylene chloride, 1 g (3.94 mmol, 0.6 eq) of 3-dodecylthiophene, 0.39 g (1.97 mmol, 0.3 eq) of 3-octylthiophene, and 0.16 g (0.66 mmol, 0.1 eq) of monomer (A) from Preparation Example 1 were added and polymerized at 30°C for 24 hours to produce polythiophene (D). The polymerization solution was placed in a permeation membrane with a molecular weight cut-off (MWCO) of 5000 and immersed in 200 ml of acetonitrile to remove unreacted iron(III) chloride monomer and low molecular weight oligomers. The residue deposited inside the membrane was washed with methanol and dried at 60° C. for 12 hours to prepare polythiophene (D).

[0218] The polythiophene (D) had a weight average molecular weight (Mw) of 136,000 g / mol and a number average molecular weight (Mn) of 28,000 g / mol, respectively, and an oxidation potential of about 3.7 V.

[0219] Electrode manufacturing An electrode was fabricated in the same manner as in Example 1, except that polythiophene (D) was used instead of polythiophene (A). At this time, the thickness of the polymer layer was about 300 nm.

[0220] Example 5. A coating solution was prepared by dispersing the polythiophene (A) obtained in Example 1 in a solvent (chloroform) at a concentration of about 2 wt %. The coating solution was coated on the current collector body using a bar coating method and maintained at 90°C for about 20 minutes to form a polymer layer with a thickness of about 300 nm. An electrode was prepared in the same manner as in Example 1, except that the coating solution was coated on the current collector body using a bar coating method and maintained at 90°C for about 20 minutes to form a polymer layer with a thickness of about 300 nm.

[0221] Comparative Example 1 Synthesis of polythiophene (E) Polythiophene (E) was produced by adding 1.66g (6.57mmol, 1eq) of 3-dodecylthiophene to a solution of 3.20g (19.71mmol, 3eq) of iron(III) chloride dissolved in 150ml of methylene chloride and polymerizing it at 30°C for 24 hours. The polymerization solution was poured into a membrane with a molecular weight cut-off (MWCO) of 5000 and then immersed in 200ml of acetonitrile to remove unreacted iron(III) chloride monomer and low molecular weight oligomers. The residue precipitated inside the membrane was washed with methanol and dried at 60°C for 12 hours to produce polythiophene (E).

[0222] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the polythiophene (E) were 138,000 g / mol and 29,500 g / mol, respectively, and the oxidation potential was about 3.7 V.

[0223] Electrode manufacturing An electrode was fabricated in the same manner as in Example 1, except that polythiophene (E) was used instead of polythiophene (A). At this time, the thickness of the polymer layer was about 300 nm.

[0224] Comparative Example 2 Synthesis of polythiophene (F) Polythiophene (F) was produced by adding 1.1 g (6.54 mmol, 1 eq) of 3-hexylthiophene 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 it at 25°C for 24 hours. The polymerization solution was poured into a membrane with a molecular weight cut-off (MWCO) of 5000 and then immersed in 200 ml of acetonitrile to remove unreacted iron(III) chloride monomer and low molecular weight oligomers. The residue precipitated inside the membrane was washed with methanol and dried at 60°C for 12 hours to produce polythiophene (F).

[0225] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polythiophene (F) were 94,000 g / mol and 21,500 g / mol, respectively, and the oxidation potential was about 3.7 V.

[0226] Electrode manufacturing An electrode was fabricated in the same manner as in Example 1, except that polythiophene (F) was used instead of polythiophene (A). At this time, the thickness of the polymer layer was about 300 nm.

[0227] Comparative Example 3. An electrode was prepared in the same manner as in Example 1, except that the polymer layer was not formed.

[0228] The measurement results for the manufactured electrodes are summarized in Tables 1 and 2 below. 1と Although C1 in Equation 4 should theoretically be the same value, some differences occurred within the error range during actual experiments. In Tables 1 and 2 below, the surface energy is the surface energy of the polymer layer in each example or comparative example, and is the surface energy of the surface of the polymer layer on which the active material layer is formed.

[0229] In Tables 1 and 2, ΔR1 is in Ω.cm / °C and ΔR2 is in Ω / °C.

[0230] [Table 1]

[0231] [Table 2] [Explanation of symbols]

[0232] 100: Collector body 200: Polymer layer 300: Active material layer

Claims

1. a current collector body; and a polymer layer formed on the current collector body, The current collector for an electrode, wherein the polymer layer comprises a copolymer including a first thiophene unit having a hydrocarbon group with 10 or more carbon atoms and a second thiophene unit having a hydrocarbon group with 9 or less carbon atoms.

2. 2. The electrode current collector according to claim 1, wherein the hydrocarbon group is a linear or branched alkyl group, an alkenyl group, or an alkynyl group.

3. 2. The electrode current collector according to claim 1, wherein the hydrocarbon group of the first thiophene unit has a carbon number of 10 to 20 in the range, and the hydrocarbon group of the second thiophene unit has a carbon number of 3 to 9 in the range.

4. 2. The electrode current collector according to claim 1, wherein the copolymer contains 80 mol % or more of thiophene units having a hydrocarbon group with 10 or more carbon atoms and 80 mol % or more of thiophene units having a hydrocarbon group with 9 or less carbon atoms.

5. 2. The electrode current collector according to claim 1, wherein a ratio M2 / M1 of the number of moles of the second thiophene units M2 to the number of moles of the first thiophene units M1 is in the range of 0.01 to 100.

6. 2. The current collector for an electrode according to claim 1, wherein the first thiophene unit is represented by the following Chemical Formula 1, and the second thiophene unit is represented by the following Chemical Formula 3: 【Chemical 1】 In Chemical Formula 1, R １ and R ２ are each independently hydrogen or a hydrocarbon group having 10 or more carbon atoms, but R １ and R ２ At least one of R is a hydrocarbon group having 10 or more carbon atoms, or １ and R ２ are linked together to form a divalent functional group of formula 2: 【Chemistry 2】 In chemical formula 2, L １ and L ２ are each independently a single bond, an alkylene group, or an alkylidene group, and R ３ and R ４ are each independently hydrogen or the hydrocarbon group having 10 or more carbon atoms, but R ３ and R ４ at least one of which is a hydrocarbon group having 10 or more carbon atoms: 【Chemistry 3】 In chemical formula 3, R ５ and R ６ are each independently hydrogen or a hydrocarbon group having 9 or less carbon atoms, but R ５ and R ６ At least one of R is a hydrocarbon group having 9 or less carbon atoms, or ５ and R ６ are linked together to form a divalent functional group of formula 4: 【Chemistry 4】 L in Chemical Formula 4 ３ and L ４ are each independently a single bond, an alkylene group, or an alkylidene group, and R ７ and R ８ are each independently hydrogen or the hydrocarbon group having 9 or less carbon atoms, but R ７ and R ８ At least one of the groups is a hydrocarbon group having 9 or less carbon atoms.

7. The current collector for an electrode according to claim 1 , wherein the copolymer further comprises a third thiophene unit having a polar functional group.

8. 8. The current collector for an electrode according to claim 7, wherein the polar functional group is a carboxyl group, a hydroxyl group, an amino group, a cyano group, a nitro group, an ether group, or a functional group of the following chemical formula 5: 【Chemistry 5】 L in Chemical Formula 5 ４ is a single bond, an alkylene group, or an alkylidene group, and L ３ is an alkylene group or an alkylidene group, and R ５ is hydrogen or an alkyl group, and n is a number in the range of 1 to 10.

9. 8. The current collector for an electrode according to claim 7, wherein the third thiophene unit is represented by the following Chemical Formula 6: 【Chemistry 6】 In chemical formula 6, R １０ and R １１ are each independently hydrogen or a polar functional group, but R １０ and R １１ one or more of the polar functional groups, or R １０ and R １１ are linked together to form a divalent functional group of formula 7: 【Chemistry 7】 In chemical formula 7, L ７ and L ８ are each independently a single bond, an alkylene group, or an alkylidene group, and R １２ and R １３ are each independently hydrogen or the polar functional group, but R １２ and R １３ At least one of the groups is the polar functional group.

10. 8. The current collector for an electrode according to claim 7, wherein the third thiophene unit in the copolymer is contained in an amount such that 1 mole to 500 moles of the first and second thiophene units are present per mole of the third thiophene unit.

11. The current collector for an electrode according to claim 1, wherein ΔR1 in the following formula 1 is 100 Ω cm / °C or more: [Formula 1] △R1=Max{(R ｎ＋５ / R ｎ ) / 5} In Equation 1, R ｎ is the DC resistance at any temperature n°C in the range of 25°C to 135°C, and R ｎ＋５ is the DC resistance at a temperature (n+5) °C which is 5 °C higher than the temperature n °C, and Max{(R ｎ＋５ / R ｎ ) / 5} was confirmed within the temperature range of 25°C to 135°C (R ｎ＋５ / R ｎ ) / 5 values.

12. △R1 is confirmed R ｎ The current collector for an electrode according to claim 11, wherein the temperature is greater than 80°C.

13. The current collector for an electrode according to claim 1, 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 is the AC impedance resistance at any temperature n°C in the range of 25°C to 135°C, and R ｚ＋５ is the AC impedance resistance at a temperature (n+5) °C which is 5 °C higher than the temperature n °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 ) / 5 values.

14. △R2 is confirmed ｚ The electrode current collector according to claim 13 , wherein the temperature is 80° C. or higher.

15. The current collector for an electrode according to claim 1, wherein the absolute value of ΔR3 in the following formula 3 is less than 10%: [Formula 3] △R3=100×(C １ -C ２ ) / C １ In Equation 3, C １ is the discharge capacity at 25°C, and C ２ is the discharge capacity after maintaining at 70°C for 60 hours.

16. The current collector for an electrode according to claim 1, wherein the absolute value of ΔR4 in the following formula 4 is 15% or more: [Formula 4] △R4=100×(C １ -C ３ ) / C １ In Equation 4, C １ is the discharge capacity at 25°C, and C ３ is the discharge capacity after maintaining the temperature at 130° C. for 10 minutes.

17. 2. The electrode current collector according to claim 1, wherein the polymer layer has a thickness in the range of 10 nm to 2 μm.

18. The current collector for an electrode according to any one of claims 1 to 17; and an electrode comprising an active material layer formed on the polymer layer of the current collector;

19. 20. An electrode assembly comprising the electrode of claim 18.

20. A secondary battery comprising the electrode according to claim 18.

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