Electrode

Abstract

This specification discloses an electrode and its uses. The electrode comprises a polymer layer exhibiting a positive temperature coefficient (PTC) effect and oxidation potential controlled for a specific purpose. Under normal conditions, such an electrode exhibits excellent electrical characteristics, such as low resistance, thereby not affecting or even improving the performance and operation of a secondary battery, and under abnormal conditions, it can ensure stability. This specification also discloses the uses of the electrode.

Description

Technology Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0135150 filed on October 19, 2022, and all contents of said patent application are incorporated herein as part of this specification.

[0002] This specification discloses electrodes and their uses. Background Technology

[0003] The application areas of energy storage technology are expanding to include mobile phones, tablets, laptop PCs, and electric vehicles.

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

[0005] Furthermore, as major developed countries curb the production of internal combustion engine-powered vehicles to address global warming and air pollution, leading automobile manufacturers are developing various electric vehicles; consequently, the importance of secondary batteries, which possess high energy density, high discharge voltage, and output stability, is steadily increasing as a power source.

[0006] However, in accordance with the above trend, the frequency of ignition or explosion accidents caused by overcharging, exposure to high temperatures, or external impact in devices or automobiles that use secondary batteries as an energy source is also increasing.

[0007] A major cause of such accidents is known to be a short circuit, in which the positive and negative electrodes inside the electrode assembly come into direct contact due to external stimuli. When a secondary battery is overcharged or exposed to high temperatures or external stimuli, the short circuit may occur due to shrinkage of the separator caused by a rise in the internal temperature of the secondary battery, or destruction of the internal structure of the secondary battery due to external impact.

[0008] When a short circuit occurs, the movement of lithium ions and electrons concentrates at the point where the positive and negative electrodes are in direct contact, which can accelerate internal heat generation. It is known that this leads to the generation of gases inside the battery, causing volume expansion and increasing the risk of ignition. The problem to be solved

[0009] This specification discloses electrodes and their uses. The purpose of this specification is to disclose an electrode comprising a polymer layer exhibiting a positive temperature coefficient (PTC) effect and oxidation potential controlled for a specific purpose. Such an electrode exhibits excellent electrical characteristics, such as low resistance, under normal conditions, thereby not affecting or even improving the performance and operation of a secondary battery, and can ensure stability under abnormal conditions. The purpose of this specification is also to disclose the uses of said electrode. means of solving the problem

[0010] In this specification, the term "room temperature" means a natural temperature that has not been heated or cooled, and may be, for example, any temperature within the range of 10°C to 30°C or a temperature of about 23°C or about 25°C.

[0011] In cases where the measurement temperature affects the physical properties mentioned in this specification, unless otherwise specifically defined, said physical property is the property measured at room temperature.

[0012] Unless otherwise specifically defined, the unit of temperature in this specification is Celsius (°C).

[0013] In this specification, the term "atmospheric pressure" refers to natural pressure that has not been pressurized or depressurized, and typically refers to a pressure of about 730 mmHg to 790 mmHg. In cases where the measured pressure affects a physical property mentioned in this specification, unless otherwise specifically defined, the physical property is the property measured at atmospheric pressure.

[0014] Among the physical properties mentioned in this specification, if the measured humidity affects the result, said physical property is the property measured at standard humidity unless specifically otherwise specified.

[0015] Humidity in standard conditions means any relative humidity within the range of 40% to 60%, for example, a relative humidity of about 55% or 60%.

[0016] In this specification, the term "normal state" means a normal operating state of a secondary battery (e.g., a normal charging or discharging state of a secondary battery) or a storage state.

[0017] In this specification, the term "abnormal state" refers to a dangerous state in which an abnormal flow of electric charge, abnormal heat generation, or explosion occurs due to external shock and / or short-circuit phenomena, or in which the likelihood of such abnormal state occurring is high.

[0018] This specification discloses an electrode.

[0019] The above electrode may include a current collector, an active material layer formed on the current collector, and a polymer layer formed between the current collector and the active material layer. FIG. 1 is a cross-sectional view of an exemplary electrode that sequentially includes the current collector (100), the polymer layer (200), and the active material layer (300). As shown in the drawing, the current collector (100), the polymer layer (200), and the active material layer (300) may be in contact with each other. If necessary, other elements may exist between the current collector (100) and the polymer layer (200) and / or between the polymer layer (200) and the active material layer (300). Additionally, although the drawing shows a case where the active material layer (300) exists only on one side of the current collector (100), the active material layer (300) may exist on both sides of the current collector (100). In this case, the polymer layer (200) may exist in two layers between each of the active material layers (300) existing on both sides of the current collector (100) and the current collector (100), or in one layer between either of the active material layers (300) existing on both sides and the current collector (100).

[0020] The above electrode may be, for example, an anode or a cathode applied to a secondary battery.

[0021] The polymer layer included in the above electrode is a layer containing a polymer. Such a polymer may be a conductive polymer described later.

[0022] The polymer layer in the electrode is configured to exhibit a controlled Positive Temperature Coefficient (PTC) effect. As is known, the PTC effect is an effect in which resistance increases with temperature. The polymer layer is configured to exhibit the PTC effect at the temperature of the abnormal state. Accordingly, the electrode exhibits stable performance in a normal state due to the excellent electrical characteristics of the polymer layer, and stability can be ensured in an abnormal state through the increase in resistance of the polymer layer.

[0023] In the above electrode, the polymer layer may exhibit an oxidation potential adjusted in relation to the active material layer.

[0024] For example, the polymer layer or the conductive polymer included therein in the electrode may have a lower oxidation potential compared to the electrode active material or the active material layer. Through such adjustment, stable performance can be maintained even when repeated charging and discharging, or high-speed charging and / or high-speed discharging, is performed on the secondary battery to which the electrode is applied.

[0025] In the above, the oxidation potential of the conductive polymer or polymer layer is the oxidation potential relative to lithium, and is the oxidation potential for lithium and lithium ions (Li / Li + (Criteria), and can be measured in the manner described in "4. Method for measuring oxidation potential (conductive polymer / polymer layer)" of the Examples section of this specification.

[0026] In the above, the oxidation potential of the electrode active material or active material layer is an oxidation potential relative to lithium, and is an oxidation potential for lithium and lithium ions (Li / Li + (Criteria) and can be measured in the manner described in "5. Method for measuring oxidation potential (electrode active material)" of the Examples section of this specification.

[0027] For example, the above electrode can be designed so that the RV of Formula 1 below is within a predetermined range.

[0028] [Equation 1]

[0029] RV = 100 × Va / Vs

[0030] In Equation 1, Va is the oxidation potential of the electrode active material or active material layer, and Vs is the oxidation potential of the conductive polymer or polymer layer.

[0031] The lower limit of the RV in Formula 1 may be approximately 100, 100.5, 101, 101.5, 102, or 102.5, and the upper limit may be approximately 200, 195, 190, 185, 180, 175, 170, 165, 160, 155, 150, 145, 140, 135, 130, 125, 120, 115, 110, 109, 108, 107, 106, 105, 104, or 103. The RV is within a range greater than or equal to any of the lower limits described above; Alternatively, it may have a range between any upper limit described above and below or less than any upper limit, and any lower limit described above and above or greater than or greater than any lower limit.

[0032] In the above Equation 1, the oxidation potential Va is determined according to the type of electrode active material and is not specifically limited. For example, the lower limit of the oxidation potential Va may be approximately 2.0V, 2.1V, 2.2V, 2.3V, 2.4V, 2.5V, 2.6V, 2.7V, 2.8V, 2.9V, 3V, 3.1V, 3.2V, 3.3V, 3.4V, 3.5V, 3.6V, 3.7V, 3.8V, 3.9V, or 4.0V, and the upper limit may be approximately 5V, 4.9V, 4.8V, 4.7V, 4.6V, 4.5V, 4.4V, 4.3V, 4.2V, 4.1V, 4.0V, 3.9V, 3.8V, 3.7V, 3.6V, 3.5V, 3.4V, It may be approximately 3.3V, 3.2V, 3.1V, 3.0V, 2.9V, 2.8V, 2.7V, 2.6V, 2.5V, 2.4V, 2.3V, 2.2V, 2.1V, or 2.0V. The oxidation potential Va may have a range greater than or equal to any of the lower limits described above; or a range less than or equal to any of the upper limits described above; or a range between any of the upper limits described above and any of the lower limits described above.

[0033] Vs of Equation 1 above is not particularly limited as long as it is controlled to satisfy the range of RV according to the oxidation potential of the applied electrode active material or active material layer. For example, the lower limit of the oxidation potential Vs is 0V, 0.1V, 0.2V, 0.3V, 0.4V, 0.5V, 0.6V, 0.7V, 0.8V, 0.9V, 1.0V, 1.1V, 1.2V, 1.3V, 1.4V, 1.5V, 1.6V, 1.7V, 1.8V, 1.9V, 2.0V, 2.1V, 2.2V, 2.3V, 2.4V, 2.5V, 2.6V, 2.7V, 2.8V, 2.9V, 3V, 3.1V, 3.2V, 3.3V, 3.4V, 3.5V, 3.6V, 3.7V, 3.8V, It may be approximately 3.9V or 4.0V, and the upper limit may be approximately 5V, 4.9V, 4.8V, 4.7V, 4.6V, 4.5V, 4.4V, 4.3V, 4.2V, 4.1V, 4.0V, 3.9V, 3.8V, 3.7V, 3.6V, 3.5V, 3.4V, 3.3V, 3.2V, 3.1V, 3.0V, 2.9V, 2.8V, 2.7V, 2.6V, 2.5V, 2.4V, 2.3V, 2.2V, 2.1V, or 2.0V. The oxidation potential Vs is within a range greater than or exceeding any of the lower limits described above; Or it may have a range below or less than any of the upper limits described above; or a range between any of the upper limits described above and above or greater than or greater than any of the lower limits described above.

[0034] The upper limit of the DC resistance of the polymer layer at 25°C in the above electrode is 10,000 Ω·cm, 9,500 Ω·cm, 9,000 Ω·cm, 8,500 Ω·cm, 8,000 Ω·cm, 7,500 Ω·cm, 7,000 Ω·cm, 6,500 Ω·cm, 6,000 Ω·cm, 5,500 Ω·cm, 5,000 Ω·cm, 4,500 Ω·cm, 4,000 Ω·cm, 3,500 Ω·cm, 3,000 Ω·cm, 2,500 Ω·cm, 2,000 Ω·cm, 1,500 Ω·cm, 1,000 Ω·cm, 950 Ω·cm, 900 Ω·cm, It may be approximately 850 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, 400 Ω·cm, or 350 Ω·cm, and the lower limit may be approximately 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, 500 Ω·cm, 550 Ω·cm, or 600 Ω·cm. The above DC resistance may be within a range below or less than any of the upper limits described above; or may be within a range below or less than any of the upper limits described above, and above or greater than any of the lower limits described above. The above DC resistance is measured in the manner described in "6. Method for measuring DC resistance" of the embodiments of this specification.

[0035] The upper limit of the AC impedance resistance of the polymer layer at the above electrode may be approximately 1,000 Ω, 950 Ω, 900 Ω, 850 Ω, 800 Ω, 750 Ω, 700 Ω, 650 Ω, 600 Ω, 550 Ω, 500 Ω, 450 Ω, 400 Ω, 350 Ω, 300 Ω, 250 Ω, 200 Ω, 150 Ω, 100 Ω, 95 Ω, 90 Ω, 85 Ω, 80 Ω, 75 Ω, 70 Ω, 65 Ω, 60 Ω, 55 Ω, or 50 Ω, and the lower limit may be approximately 10 Ω, 15 Ω, 20 Ω, It may be approximately 25 Ω, 30 Ω, 35 Ω, 40 Ω, 450 Ω, 50 Ω, 55 Ω, 60 Ω, 65 Ω, 70 Ω, 75 Ω, 80 Ω, or 85 Ω. The AC impedance resistance may be within a range below or less than any of the upper limits described above; or may be within a range between any of the upper limits described above and above or greater than any of the lower limits described above. The AC impedance resistance is measured in the manner described in "7. Interface Resistance (AC Impedance Resistance)" of the embodiments of this specification.

[0036] By the fact that the polymer layer exhibits the DC resistance and / or AC impedance resistance, the electrode or the secondary battery or electrode assembly to which the electrode is applied can be stably operated or stored in a normal state.

[0037] The above polymer layer can exhibit a PTC effect designed for the purpose.

[0038] For example, the above polymer layer may exhibit characteristics such that △R1 of Formula 2 below is within a predetermined range.

[0039] [Equation 2]

[0040] △R1 = Max{(R n+5 / R n ) / 5}

[0041] R in Equation 1n is a DC resistance at any temperature n℃ within the range of 25℃ to 135℃, and R n+5 is the DC resistance at a temperature 5℃ higher ((n+5)℃) than the above temperature n℃, and Max{(R n+5 / R n ) / 5} is (R confirmed within a temperature range of 25℃ to 135℃ n+5 / R n It is the maximum value among ) / 5 values.

[0042] △R1 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 (DC Resistance)" of the Examples. In the method for verifying △R1, the initial temperature is 25°C and the final temperature is 135°C. By increasing the temperature by 5°C increments from the initial temperature of 25°C and measuring the DC resistance at each temperature, the R n+5 and R n Check. For example, in the case where n is 90, R 95 / R 90 ...is the ratio of the DC resistance at 95°C to the DC resistance at 90°C. For example, the fact that △R1 is 100Ω·cm / °C or more at any temperature within the temperature range of 25°C to 135°C means that the resistance of the polymer layer increases relatively rapidly at any temperature within the above temperature range.

[0043] The lower limit of the above △R1 may be approximately 40, 45, 50, 55, 60, 65, 70, 75, 80, 90, 100, 150, 200, 250, 300, 350, or 400, and the upper limit may be approximately 1,000, 950, 900, 850, 800, 750, 700, 650, 600, 550, 500, 450, 400, 350, 300, 250, 200, or 150. The unit of the above △R1 is Ω·cm / ℃. The above △R1 is within a range greater than or exceeding any of the lower limits described above; Alternatively, it may have a range between any upper limit described above and below or less than any upper limit, and any lower limit described above and above or greater than. Through the above characteristics, the polymer electrode can ensure the stability of a secondary battery, etc., in an ideal state.

[0044] The temperature at which the above △R1 is confirmed, i.e., R nThe lower limit of the temperature at may be approximately 70℃, 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 91℃, 92℃, 93℃, 94℃, or 95℃, and the upper limit may be approximately 200℃, 190℃, 180℃, 170℃, 160℃, 150℃, 140℃, 130℃, 120℃, 110℃, 100℃, or 90℃. The above temperature is within a range below or less than any of the upper limits described above; Alternatively, it may have a range greater than or exceeding any of the lower limits described above, or a range between any of the upper limits described above, which is less than or equal to, and greater than or exceeding any of the lower limits described 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 characteristics is applied, the electrode, electrode assembly, or secondary battery can ensure stability under abnormal conditions while maintaining stable performance even when storage in a normal state is performed at a relatively high temperature and when charging and discharging are performed at high temperatures.

[0045] The above polymer may exhibit characteristics in which △R2 of Formula 3 below is within a predetermined range.

[0046] [Equation 3]

[0047] △R2 = Max{(R z+5 / R z ) / 5}

[0048] R in Equation 2 z is an AC impedance resistance at any temperature n℃ within the range of 25℃ to 135℃, and R z+5 is the AC impedance resistance at a temperature 5°C higher than the above temperature n°C ((n+5)°C), and Max{(R z+5 / R z ) / 5} is (R confirmed within a temperature range of 25℃ to 135℃ z+5 / R zIt is the maximum value among ) / 5 values.

[0049] △R2 in Equation 3 is measured for the polymer layer applied to the coin cell, and the specific method is described in "9. Measurement of Maximum Resistance Change Rate (AC Impedance)" of the Examples. In the method for verifying △R2, the initial temperature is 25°C and the final temperature is 135°C. By increasing the temperature by 5°C increments from the initial temperature of 25°C and measuring the AC impedance resistance at each temperature, the R z+5 and R z Check . For example, in the case where n is 90, R 95 / R 90 ΔR2 is the ratio of the AC impedance resistance at 95°C to the AC impedance resistance at 90°C. For example, the fact that ΔR2 is 10Ω / °C or more at any temperature within the temperature range of 25°C to 135°C means that the resistance of the polymer layer increases relatively rapidly at any temperature within the said temperature range.

[0050] The lower limit of the above △R2 may be approximately 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 approximately 100, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 18, or 16. The unit of the above △R2 is Ω / ℃. The above △R2 may have a range between being less than or equal to any of the upper limits described above, being greater than or equal to any of the lower limits described above, or being less than or equal to any of the upper limits described above while being greater than or equal to any of the lower limits described above. Through the above characteristics, the electrode to which the polymer layer polymer is applied can ensure the stability of a secondary battery, etc., in an abnormal state.

[0051] The temperature at which △R2 of the above range is confirmed, i.e., R z The lower limit of the temperature at may be approximately 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 91℃, 92℃, 93℃, 94℃, or 95℃, and the upper limit may be approximately 200℃, 190℃, 180℃, 170℃, 160℃, 150℃, 140℃, 130℃, 120℃, 110℃, 100℃, or 90℃. The above temperature is within a range lower than or equal to any of the upper limits described above; or within a range greater than or equal to any of the lower limits described above; Alternatively, it may have a range between any upper limit described above and below or less than any upper limit, and any lower limit described above and above or greater than. 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 characteristics is applied, the electrode, electrode assembly, or secondary battery can ensure stability under abnormal conditions while maintaining stable performance even when storage in a normal state is performed at a relatively high temperature and when charging and discharging are performed at high temperatures.

[0052] The conductive polymer forming the polymer layer can be controlled so that the polymer layer exhibits an oxidation potential and PTC effect controlled as described above.

[0053] The conductive polymer included in the above polymer layer may be a polythiophene or thiophene polymer. In this specification, the term polythiophene or thiophene polymer refers to a polymer containing thiophene units at a certain level or higher. The thiophene unit refers to a monomer unit formed by the polymerization of thiophene-based monomers, and the thiophene-based monomer refers to a monomer containing a thiophene backbone.

[0054] The term "monomer unit" above refers to a structure in which monomers are polymerized and contained within a polymer.

[0055] The lower limit of the proportion of the thiophene unit in the above polythiophene or thiophene polymer may be about 10 mol%, 15 mol%, 20 mol%, 25 mol%, 30 mol%, 35 mol%, 40 mol%, 45 mol%, 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, 85 mol%, 90 mol%, or 95 mol% based on the total moles of all monomer units in the above polythiophene or thiophene polymer, and the upper limit may be 99 mol%, 97 mol%, 95 mol%, 93 mol%, 91 mol%, 89 mol%, 87 mol%, 85 mol%, 83 mol%, 81 mol%, 79 mol%, 77 mol%, 75 mol%, 73 mol%, The ratio of the thiophene units may be approximately 71 mol%, 69 mol%, 67 mol%, 65 mol%, 63 mol%, 61 mol%, 59 mol%, 57 mol%, 55 mol%, 53 mol%, or 51 mol%. The ratio of the thiophene units may be within a range greater than or greater than any of the lower limits described above; or may be within a range between any of the upper limits described above and greater than or greater than any of the lower limits described above.

[0056] As for the thiophene units included in the above polythiophene, thiophene units having hydrocarbon functional groups may be applied.

[0057] In this specification, the term hydrocarbon functional group refers to a monovalent hydrocarbon group (i.e., a monovalent functional group composed of carbon and hydrogen) or a monovalent functional group comprising said monovalent hydrocarbon group. Accordingly, said hydrocarbon functional group may include atoms other than carbon and hydrogen. Examples of said monovalent hydrocarbon groups include alkyl groups, alkynyl groups, or alkenyl groups, and examples of said monovalent functional groups comprising said monovalent hydrocarbon groups include alkoxy groups, alkyl carbonyl groups, or alkyl carbonyloxy groups, but the types of hydrocarbon functional groups are not limited thereto.

[0058] The lower limit of the number of carbon atoms in the hydrocarbon functional group may be approximately 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, and the upper limit may be approximately 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, or 3. The number of carbon atoms may be within a range greater than or exceeding any of the lower limits described above; or within a range less than or equal to any of the upper limits described above; or between any of the upper limits described above and greater than or equal to any of the lower limits described above.

[0059] The above number of carbons may be the total number of carbons of the hydrocarbon functional group or the monovalent hydrocarbon group included therein, or the number of carbons of the longest straight-chain hydrocarbon chain included in the hydrocarbon functional group or the monovalent hydrocarbon group included therein. That is, the hydrocarbon functional group or the monovalent hydrocarbon group may have a straight-chain structure or a branched-chain structure, and even in the case of a branched-chain structure, the number of carbons constituting the longest straight-chain in the branched-chain structure may be within the above range. For example, if the branched-chain structure is the structure of a 2-ethylhexyl group, the number of carbons constituting the longest chain is 6.

[0060] The above hydrocarbon functional groups, such as alkyl groups, alkenyl groups, alkynyl groups, alkoxy groups, alkyl carbonyl groups, or alkyl carbonyloxy groups, may optionally be substituted with one or more substituents.

[0061] In the conductive polymer above, the lower limit of the ratio of the moles of thiophene units having hydrocarbon functional groups may be approximately 10 mol%, 15 mol%, 20 mol%, 25 mol%, 30 mol%, 35 mol%, 40 mol%, 45 mol%, 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, or 85 mol%, and the upper limit may be approximately 95 mol%, 90 mol%, 85 mol%, 80 mol%, 75 mol%, 70 mol%, 65 mol%, 60 mol%, 55 mol%, 50 mol%, or 45 mol%. The ratio is a ratio based on the total moles of all monomer units included in the polymer. The ratio is within a range below or less than any of the upper limits described above; Or it may have a range greater than or equal to any of the lower limits described above or greater than or equal to any of the upper limits described above, and a range between any of the lower limits described above or greater than or equal to any of the lower limits described above or greater than or equal to

[0062] By including the thiophene unit in the conductive polymer, the polymer or the polymer layer containing it can exhibit an appropriate Positive Temperature Coefficient (PTC) effect, and its surface characteristics can be controlled to ensure excellent adhesion to the electrode or current collector, and can exhibit an appropriate level of oxidation potential.

[0063] The above hydrocarbon functional group is a functional group capable of imparting appropriate mobility to the polymerization process of the conductive polymer or to the conductive polymer itself. Such a functional group imparts appropriate mobility to the monomer mixture and also diffuses within the monomer mixture to enable polymerization to occur with excellent efficiency. Furthermore, the conductive polymer having the above functional group can enable the stable and uniform formation of a polymer layer between the current collector and the active material layer through appropriate mobility.

[0064] The above hydrocarbon functional groups may be appropriately oriented during the drying or annealing process (heat treatment process) applied during the formation of the polymer layer to impart a PTC effect and oxidation potential characteristics suitable for the polymer.

[0065] When a certain amount of thermal energy is applied, the hydrocarbon functional group vibrates due to the heat, and this vibration (thermal vibration) promotes the dedoping of anions bonded to the polymer, 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 functional group. For example, at the same temperature, the thermal vibration of a relatively long chain is greater than that of a relatively short chain, and accordingly, the long chain can induce a resistance increase effect at a relatively lower temperature. Therefore, the desired PTC effect can be set by controlling the length and / or ratio of the hydrocarbon functional group.

[0066] As for the thiophene units of the above hydrocarbon functional groups, a first thiophene unit having a long-chain hydrocarbon functional group and a second thiophene unit having a short-chain hydrocarbon functional group may be included in the polymer.

[0067] The term "long-chain hydrocarbon functional group" refers to a hydrocarbon functional group according to the description above, provided that the number of carbon atoms is adjusted to a certain level or higher.

[0068] The term "short-chain hydrocarbon functional group" refers to a hydrocarbon functional group according to the description above, provided that the number of carbon atoms is adjusted to a level below a certain threshold.

[0069] The lower limit of the number of carbon atoms in the long-chain hydrocarbon functional group may be approximately 10, 11, or 12, and the upper limit may be approximately 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, or 10. The number of carbon atoms in the long-chain hydrocarbon functional group may be within a range greater than or greater than any of the lower limits described above; or may be within a range between any of the upper limits described above and greater than or greater than any of the lower limits described above.

[0070] The lower limit of the number of carbon atoms in the above-mentioned short-chain hydrocarbon functional group may be approximately 3, 4, 5, 6, 7, or 8, and the upper limit may be approximately 9, 8, 7, or 6. The number of carbon atoms in the above-mentioned short-chain hydrocarbon functional group may be within a range below or less than any of the upper limits described above; or may be within a range between any of the upper limits described above and above or greater than any of the lower limits described above.

[0071] The specific description of the above long-chain and short-chain hydrocarbon functional groups is as described for the hydrocarbon functional groups, except for the number of carbon atoms.

[0072] In the conductive polymer above, the lower limit of the ratio of the total moles of the first and second thiophene units may be approximately 10 mol%, 15 mol%, 20 mol%, 25 mol%, 30 mol%, 35 mol%, 40 mol%, 45 mol%, 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, or 85 mol%, and the upper limit may be approximately 95 mol%, 90 mol%, 85 mol%, 80 mol%, 75 mol%, 70 mol%, 65 mol%, 60 mol%, 55 mol%, 50 mol%, or 45 mol%. The ratio is a ratio based on the total moles of all monomer units included in the polymer. The ratio is within a range below or less than any of the upper limits described above; Or it may have a range greater than or equal to any of the lower limits described above or greater than or equal to any of the upper limits described above, and a range between any of the lower limits described above or greater than or equal to any of the lower limits described above or greater than or equal to

[0073] The lower limit of the ratio (M2 / M1) of the moles (M2) of the second thiophene unit to the moles (M1) of the first thiophene unit in the conductive polymer may be approximately 0.01, 0.05, 0.1, 0.5, 1, 1.5, or 2, and the upper limit may be approximately 100, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.8, 0.7, 0.6, or 0.55. The ratio is within a range below or less than any of the upper limits described above; Or it may have a range greater than or equal to any of the lower limits described above or greater than or equal to any of the upper limits described above, and a range between any of the lower limits described above or greater than or equal to any of the lower limits described above or greater than or equal to

[0074] Under these ratios, the conductive polymer or the polymer layer exhibits an appropriate Positive Temperature Coefficient (PTC) effect, and its surface characteristics can be controlled to ensure excellent adhesion to the electrode or current collector.

[0075] The above polymer may additionally include a thiophene unit having a polar functional group along with a thiophene unit having a hydrocarbon functional group as the thiophene unit.

[0076] The term polar functional group is a functional group containing one or more polar atoms, e.g., oxygen and / or nitrogen. Examples of such polar functional groups include, but are not limited to, carboxyl groups, hydroxyl groups, amino groups, cyano groups, nitro groups, ether groups, or functional groups of Formula 1 below.

[0077] [Chemical Formula 1]

[0078]

[0079] In Chemical Formula 1, L3 is a single bond, an alkylene group, or an alkylidene group, L4 is an alkylene group or an alkylidene group, R8 is hydrogen or an alkyl group, and n is any number.

[0080] In Chemical Formula 1, the fact that L3 is a single bond means that L3 is absent, and the oxygen atom between L4 and L3 is directly connected to the backbone of the monomer or polymer.

[0081] In this specification, the term alkylene group refers to a divalent functional group formed by the removal of hydrogen atoms from two different carbon atoms in an alkane, and the term alkylidene group refers to a divalent functional group formed by the removal of two hydrogen atoms from one carbon atom in an alkane.

[0082] In this specification, the term alkylene group may be an alkylene group having 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms, unless specifically otherwise defined. The alkylene group may be straight-chain, branched-chain, or cyclic, and may optionally be substituted with one or more substituents.

[0083] In this specification, the term alkylidene group may be an alkylidene group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, unless specifically otherwise defined. The alkylidene group may be straight-chain, branched-chain, or cyclic, and may optionally be substituted with one or more substituents.

[0084] The alkyl group of R8 in Formula 1 may, in one example, be an alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, or may be a methyl group or an ethyl group. The alkyl group may be straight-chain, branched-chain, or cyclic, and suitably may be straight-chain or branched-chain.

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

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

[0087] In the case where a thiophene unit having the polar functional group is present in the conductive polymer, the thiophene unit having the polar functional group may be present such that the total number of moles of the thiophene unit having the hydrocarbon functional group is within a predetermined range per mole of the thiophene unit having the polar functional group.

[0088] For example, the lower limit of the ratio (i.e., M / M3) of the total moles (M) of thiophene units having hydrocarbon functional groups to the moles (M3) of thiophene units having polar functional groups may be approximately 1, 2, 3, 4, 5, 6, 8 moles or 8.5 moles, and the upper limit may be approximately 500, 450, 400, 350, 300, 250, 200, 150, 100, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 9.5 moles or 9 moles. The ratio is within a range below or less than any of the upper limits described above; Or it may have a range greater than or equal to any of the lower limits described above or greater than or equal to any of the upper limits described above, and a range between any of the lower limits described above or greater than or equal to any of the lower limits described above or greater than or equal to

[0089] The above-mentioned thiophene unit may be, for example, a unit of the following chemical formula 2.

[0090] [Chemical Formula 2]

[0091]

[0092] In Chemical Formula 2, R1 and R2 may each independently be hydrogen, the polar functional group, or the hydrocarbon functional group.

[0093] In another example, R1 and R2 of Chemical Formula 1 may be connected to each other to form the 2-valent functional group of Chemical Formula 3 below.

[0094] [Chemical Formula 3]

[0095]

[0096] In Chemical Formula 3, L1 and L2 are each independently a single bond, an alkylene group, or an alkylidene group, and R3 and R4 are each independently hydrogen, the polar functional group, or the hydrocarbon functional group.

[0097] For example, if the unit of the above chemical formula 2 is a thiophene unit having the aforementioned hydrocarbon functional group, one or more of R1 and R2 may be the hydrocarbon functional group (if R1 and R2 are not connected), or one or more of R3 and R4 may be the hydrocarbon functional group (if R1 and R2 are not connected).

[0098] For example, if the unit of the above chemical formula 2 is a thiophene unit having the aforementioned polar functional group, one or more of R1 and R2 may be the polar functional group (if R1 and R2 are not connected), or one or more of R3 and R4 may be the polar functional group (if R1 and R2 are not connected).

[0099] For example, in the case where the unit of the above chemical formula 2 is the aforementioned first thiophene unit, one or more of R1 and R2 may be the long-chain hydrocarbon functional group described above (where R1 and R2 are not connected), or one or more of R3 and R4 may be the long-chain hydrocarbon functional group described above (where R1 and R2 are not connected).

[0100] For example, in the case where the unit of the above chemical formula 2 is the aforementioned second thiophene unit, one or more of R1 and R2 may be the short-chain hydrocarbon functional group described above (where R1 and R2 are not connected), or one or more of R3 and R4 may be the short-chain hydrocarbon functional group described above (where R1 and R2 are not connected).

[0101] The specific description of the above hydrocarbon functional groups, polar functional groups, long-chain hydrocarbon functional groups, and short-chain hydrocarbon functional groups is as previously stated.

[0102] In addition, the specific description of the alkylene group and alkylidene group of the above chemical formula 3 is as described in the above chemical formula 1.

[0103] The polymer may include additional monomer units along with the thiophene unit. For example, additional monomers may be included to adjust the oxidation potential of the polymer. For example, units exhibiting a lower or higher oxidation potential relative to the thiophene unit may be included in the conductive polymer as needed.

[0104] The above polymer may have a weight average molecular weight (Mw) within a predetermined range. The lower limit of the weight-average molecular weight of the above polymer is 10,000 g / mol, 11,000 g / mol, 12,000 g / mol, 13,000 g / mol, 14,000 g / mol, 15,000 g / mol, 16,000 g / mol, 17,000 g / mol, 18,000 g / mol, 19,000 g / mol, 20,000 g / mol, 21,000 g / mol, 22,000 g / mol, 23,000 g / mol, 24,000 g / mol, 25,000 g / mol, 26,000 g / mol, 27,000 g / mol, 28,000 g / mol, 29,000 g / mol, 30,000 g / mol, It may be approximately 31,000 g / mol, 32,000 g / mol, 33,000 g / mol, 34,000 g / mol, 35,000 g / mol, 36,000 g / mol, 37,000 g / mol, 38,000 g / mol, 39,000 g / mol, or 40,000 g / mol, and the upper limit is 2,000,000 g / mol, 1,500,000 g / mol, 1,000,000 g / mol, 900,000 g / mol, 800,000 g / mol, 700,000 g / mol, 600,000 g / mol, 500,000 g / mol, 400,000 g / mol, 300,000 g / mol, 295,000 g / mol, 290,000 g / mol, 285,000 g / mol, 280,000 g / mol, 275,000 g / mol, 270,000 g / mol, 265,000 g / mol, 260,000 g / mol, 255,000 g / mol, 250,000 g / mol, 245,000 g / mol, 240,000 g / mol, 235,000 g / mol, 230,000 g / mol, 225,000 g / mol, 220,000 g / mol, 215,000 g / mol, 210,000 g / mol, 205,000 g / mol, 200,000 g / mol,It may be approximately 195,000 g / mol, 190,000 g / mol, 185,000 g / mol, 180,000 g / mol, 175,000 g / mol, 170,000 g / mol, 165,000 g / mol, 160,000 g / mol, 155,000 g / mol, 150,000 g / mol, 145,000 g / mol, 140,000 g / mol, 135,000 g / mol, 130,000 g / mol, 125,000 g / mol, 120,000 g / mol, 115,000 g / mol, 110,000 g / mol, 105,000 g / mol, or 100,000 g / mol. The weight-average molecular weight may be within a range below or less than any of the upper limits described above; within a range above or greater than any of the lower limits described above; or between a range below or less than any of the upper limits described above and a range above or greater than any of the lower limits described above.

[0105] The molecular weight distribution of the above polymer, that is, the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn), may be within a predetermined range. The lower limit of the above molecular weight distribution may be approximately 2, 2.5, 3, 3.5, or 4, and the upper limit may be approximately 8, 7.5, 7, 6.5, 6, 5.5, 5, 4.5, 4, or 3.5. The molecular weight distribution may have a range within which it is below or less than any of the upper limits described above; or within which it is above or greater than any of the lower limits described above; or between which it is below or less than any of the upper limits described above and above or greater than any of the lower limits described above.

[0106] The above weight-average molecular weight and molecular weight distribution are measured in the manner described in "2. GPC (Gel Permeation Chromatograph)" of the Examples section of this specification.

[0107] The polymer layer may include the polymer. The polymer layer may be composed of only the polymer, or may additionally include any other necessary additives in addition to the polymer. By using the polymer, a desired electrode can be effectively formed. In one example, the lower limit of the content of the polymer in the polymer layer may be approximately 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, or 95 wt%, and the upper limit may be approximately 100 wt%, 95 wt%, 90 wt%, or 85 wt% based on the total weight of the polymer layer. The above ratio is based on the total weight of the polymer layer. The range of the above ratio is within a range below or less than any of the upper limits described above; Or it may have a range greater than or equal to any of the lower limits described above or greater than or equal to any of the upper limits described above, and a range between any of the lower limits described above or greater than or equal to any of the lower limits described above or greater than or equal to

[0108] The thickness of the polymer layer described above can be appropriately controlled according to the purpose. For example, the lower limit of the thickness may be approximately 10 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, or 500 nm, and the upper limit may be approximately 2 μm, 1.5 μm, 1 μm, 950 nm, 900 nm, 850 nm, 800 nm, 750 nm, 700 nm, 650 nm, 600 nm, 550 nm, 500 nm, 450 nm, 400 nm, 350 nm, or 300 nm. The thickness may be within a range below or less than any of the upper limits described above; or within a range above or greater than any of the lower limits described above. Alternatively, it may have a range between any upper limit described above and below or less than any upper limit, and any lower limit described above and above or greater than. The thickness may be measured in the manner described in "3. Thickness Measurement" of the Examples section of this specification.

[0109] As for the current collector included in the above electrode, one that is typically used as a current collector for an anode or a cathode can be used without any special limitations.

[0110] As for the current collector mentioned above, as long as it is conductive without causing chemical changes in the application device such as a secondary battery, its type, size, and shape are not particularly limited. Examples of materials that can be used as the current collector include copper, aluminum, stainless steel, nickel, titanium, or calcined carbon, or materials in which the surface of copper, aluminum, or stainless steel is surface-treated with carbon, nickel, titanium, or silver, etc. The current collector may be in the form of a film, sheet, foil, net, porous body, foam, or nonwoven fabric containing the above materials. In some cases, a known surface treatment may be performed on the surface of the current collector to improve adhesion to other layers, such as a polymer layer or an active material layer.

[0111] These current collectors may typically have a thickness within the range of 3 μm to 500 μm, but are not limited thereto.

[0112] A layer that is typically applied as the above active material layer can also be used.

[0113] Typically, the active material layer comprises an electrode active material. There are no specific restrictions on the specific type of the electrode active material, and a material that forms a positive electrode or a negative electrode can be used.

[0114] For example, when the above active material layer is a positive electrode active material layer, the electrode active material is a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; lithium iron oxide such as LiFe3O4; and a compound with the chemical formula Li 1+c1 Mn 2-c1 Lithium manganese oxides such as O4 (0≤c1≤0.33), LiMnO3, LiMn2O3, or LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, or Cu2V2O7; chemical formula LiNi 1-c2 M c2Ni-site type lithium nickel oxide represented by O2 (wherein M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, satisfying 0.01≤c2≤0.3); chemical formula LiMn 2-c3 M c3 A lithium manganese composite oxide represented by O2 (wherein M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn and Ta, satisfying 0.01≤c3≤0.1) or Li2Mn3MO8 (wherein M is at least one selected from the group consisting of Fe, Co, Ni, Cu and Zn); may be a lithium nickel cobalt manganese (NCM) composite oxide, a lithium nickel cobalt manganese aluminum (NCMA) composite oxide, and LiMn2O4 in which part of the Li of the chemical formula is substituted with an alkaline earth metal ion, but is not limited thereto.

[0115] When the above active material layer is a negative active material layer, the electrode active material may be a compound capable of reversible intercalation and deintercalation of lithium. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; metal oxides capable of doping and dedoping lithium, such as SiOa (0 < a < 2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites comprising the above metallic compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or more of these may be used.

[0116] As the above-mentioned cathode active material, a lithium thin film may be used, and as a carbon material, low-crystallinity carbon and high-crystallinity carbon may be used. Representative examples of low-crystallinity carbon include soft carbon and hard carbon, while representative examples of high-crystallinity carbon include amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesocarbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch-derived cokes.

[0117] The above electrode active material may be included in the active material layer in a range of about 80% to 99.5% by weight or 88% to 99% by weight relative to the total weight of the active material layer, but the above ratio may be changed depending on the use or design of the electrode.

[0118] The active material layer may additionally include a binder. The binder serves to improve adhesion between active materials and adhesion between the active material layer and the current collector. Examples of the above binders are not particularly limited, and include, for example, PVDF (Poly(vinylidene fluoride)), PVA (poly(vinyl alcohol)), SBR (styrene butadiene rubber), PEO (poly(ethylene oxide)), CMC (carboxyl methyl cellulose), cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, cyanoethylpullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, One or more materials may be selected from the group consisting of polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, and polyarylate.

[0119] In one example, the binder may be included in the active material layer in a range of 0.1 to 10 parts by weight or 0.5 to 5 parts by weight relative to 100 parts by weight of the electrode active material, but is not limited thereto.

[0120] The above active material layer may additionally include a conductive material as needed. As for the conductive material, any known material may be used without special limitations as long as it is conductive without causing chemical changes in the secondary battery. For example, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, Farnes black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; conductive tubes such as carbon nanotubes (CNT); metal powders such as fluorocarbon, aluminum, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide and / or conductive materials such as polyphenylene derivatives may be used.

[0121] The above conductive material may be included in an amount of 0.1 to 20 parts by weight or 0.3 to 10 parts by weight relative to 100 parts by weight of the electrode active material in one example, and may be included in the active material layer, but is not limited thereto.

[0122] The active material layer may optionally include additional known components in addition to the components described above.

[0123] The present specification also discloses a method for manufacturing the electrode.

[0124] The above manufacturing method may include the step of forming the polymer layer on the current collector and the step of forming the active material layer on the polymer layer.

[0125] There are no particular limitations on the method of forming the above polymer layer on the current collector. For example, the polymer layer can be formed by preparing a coating solution by diluting the aforementioned conductive polymer and, if necessary, other additives in a suitable solvent, coating it onto the current collector, and then drying it.

[0126] In another example, the monomers forming the conductive polymer may be directly polymerized on the current collector to form the polymer layer.

[0127] The preparation of the coating composition and the coating method for forming the above polymer layer are not particularly limited, and methods from known coating methods may be applied. Furthermore, the method for polymerizing the above conductive polymer is not particularly limited, and known methods may be applied. For example, methods using oxidative polymerization or radical reactions are known as representative methods for manufacturing polythiophene, and such methods may also be applied to the process of forming the above conductive polymer in this application.

[0128] A polymer layer can be formed on a current collector using the coating composition prepared above. This process may typically include the steps of coating the coating composition onto the current collector and heat-treating the coated coating composition. In this process, the characteristics of the polymer layer can also be controlled by the conditions of the heat treatment.

[0129] For example, the temperature T of the heat treatment and / or the time H of the heat treatment can be controlled.

[0130] For example, the lower limit of the above temperature T may be approximately 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, or 140℃, and the upper limit may be approximately 300℃, 295℃, 290℃, 285℃, 280℃, 275℃, 270℃, 265℃, 260℃, 255℃, 250℃, 245℃, 240℃, 235℃, 230℃, 225℃, 220℃, 215℃, 210℃, 205℃, The temperature may be approximately 200℃, 195℃, 190℃, 185℃, 180℃, 175℃, 170℃, 165℃, 160℃, 155℃, 150℃, 145℃, 140℃, 135℃, 130℃, 125℃, 120℃, 115℃, 110℃, 105℃, 100℃, 95℃, or 90℃. The above temperature may be within a range below or less than any of the upper limits described above; or within a range above or greater than any of the lower limits described above; or within a range between any of the upper limits described above and above or greater than any of the lower limits described above. Within this range, the alignment state of the hydrocarbon groups of the conductive polymer can be appropriately controlled, and accordingly, the desired characteristics can be secured.

[0131] To achieve the objective, the product of the heat treatment temperature T and time H (T×H) can be adjusted. For example, the lower limit of the product of the heat treatment temperature T and time H (T×H) is 0.01℃·hour, 0.05℃·hour, 0.1℃·hour, 0.2℃·hour, 0.3℃·hour, 0.5℃·hour, 1℃·hour, 5℃·hour, 10℃·hour, 15℃·hour, 20℃·hour, 25℃·hour, 30℃·hour, 35℃·hour, 40℃·hour, 45℃·hour, 50℃·hour, 75℃·hour, 100℃·hour, 110℃·hour, 120℃·hour 또는 130℃·hour 정도일 수 있고, 그 상한은, 100000℃·hour, 95000℃·hour, 90000℃·hour, 85000℃·hour, 80000℃·hour, 75000℃·hour, 70000℃·hour, 65000℃·hour, 60000℃·hour, 55000℃·hour, 50000℃·hour, 45000℃·hour, 40000℃·hour, 35000℃·hour, 30000℃·hour, 25000℃·hour, 20000℃·hour, 15000℃·hour, 10000℃·hour, 9500℃·hour, 9000℃·hour, 8500℃·hour, 8000℃·hour, 7500℃·hour, 7000℃·hour, 6500℃·hour, 6000℃·hour, 5500℃·hour, 5000℃·hour, 4500℃·hour, 4000℃·hour, 3500℃·hour, 3000℃·hour, 2500℃·hour, 2000℃·hour, 1500℃·hour, 1400℃·hour, 1300℃·hour, 1200℃·hour, 1100℃·hour, 1000℃·hour, 900℃·hour, 800℃·hour, 700℃·hour, 600℃·hour, 500℃·hour, 400℃·hour, 300℃·hour, 200℃·hour, 100℃·hour, 90℃·hour, 80℃·hour, 70℃·hour, 60℃·hour, 50℃·hour, 45℃·hour, 40℃·hour, 35℃·hour, 30℃·hour, 25℃·hour, 20℃·hour, 15℃·hour, 10℃·hour, 5℃·hour, 4℃·hour, 3℃·hour, 2℃·hour, 1℃·hour 또는 0.5℃·hour 정도일 수도 있다.The above product (T×H) may be within a range below or less than any of the upper limits described above; or within a range above or greater than any of the lower limits described above; or within a range between any of the upper limits described above and above or greater than any of the lower limits described above. Within such a range, the alignment state of the hydrocarbon groups of the conductive polymer can be appropriately controlled, and the desired characteristics can be secured accordingly.

[0132] In order to more effectively secure the desired characteristics, the above heat treatment can be performed in two stages.

[0133] For example, the heat treatment may include the step of first heat treating the coating composition at a first temperature T1 for a first time H1 and the step of second heat treating 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.

[0134] For example, the lower limit of the above temperature T1 may be approximately 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, or 140°C, and the upper limit may be approximately 300°C, 295°C, 290°C, 285°C, 280°C, 275°C, 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, The temperature may be approximately 200℃, 195℃, 190℃, 185℃, 180℃, 175℃, 170℃, 165℃, 160℃, 155℃, 150℃, 145℃, or 140℃. The above temperature may be within a range below or less than any of the upper limits described above; or within a range above or greater than any of the lower limits described above; or within a range between any of the upper limits described above and above or greater than any of the lower limits described above. Within this range, the alignment state of the hydrocarbon groups of the conductive polymer can be appropriately controlled, and accordingly, the desired characteristics can be secured.

[0135] For example, the lower limit of the product of the temperature T1 and time H1 of the above first heat treatment (T1×H1) may be approximately 0.01℃·hour, 0.05℃·hour, 0.1℃·hour, 0.2℃·hour, or 0.3℃·hour, and the upper limit may be 1000℃·hour, 900℃·hour, 800℃·hour, 700℃·hour, 600℃·hour, 500℃·hour, 400℃·hour, 300℃·hour, 200℃·hour, 100℃·hour, 90℃·hour, 80℃·hour, 70℃·hour, 60℃·hour, 50℃·hour, 45℃·hour, 40℃·hour, 35℃·hour, 30℃·hour, 25℃·hour, 20℃·hour, It may be approximately 15°C·hour, 10°C·hour, 5°C·hour, 4°C·hour, 3°C·hour, 2°C·hour, 1°C·hour, or 0.5°C·hour. The product (T1×H1) may be within a range below or less than any upper limit among the upper limits described above; or within a range above or greater than any lower limit among the lower limits described above; or within a range between any upper limit among the upper limits described above and above or greater than any lower limit among the lower limits described above. Within such a range, the alignment state of the hydrocarbon groups of the conductive polymer is appropriately controlled, and accordingly, the desired characteristics can be secured.

[0136] For example, for example, the lower limit of the heat treatment temperature T2 of the above secondary heat treatment may be approximately 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, or 130℃, and the upper limit may be approximately 300℃, 295℃, 290℃, 285℃, 280℃, 275℃, 270℃, 265℃, 260℃, 255℃, 250℃, 245℃, 240℃, 235℃, 230℃, 225℃, 220℃, 215℃, 210℃, 205℃, The temperature may be approximately 200℃, 195℃, 190℃, 185℃, 180℃, 175℃, 170℃, 165℃, 160℃, 155℃, 150℃, 145℃, 140℃, 135℃, or 130℃. The above temperature may be within a range below or less than any of the upper limits described above; or within a range above or greater than any of the lower limits described above; or within a range between any of the upper limits described above and above or greater than any of the lower limits described above. Within this range, the alignment state of the hydrocarbon groups of the conductive polymer can be appropriately controlled, and accordingly, the desired characteristics can be secured.

[0137] The product of the above secondary heat treatment temperature T2 and 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 approximately 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 approximately 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, It may be approximately 140°C·hour, 135°C·hour, or 130°C·hour. The product (T2×H2) may be within a range below or less than any of the upper limits described above; or within a range above or greater than any of the lower limits described above; or within a range between any of the upper limits described above and above or greater than any of the lower limits described above. Within this range, the alignment state of the hydrocarbon groups of the conductive polymer is appropriately controlled, and accordingly, the desired characteristics can be secured.

[0138] In the above case, the lower limit of the ratio T1 / T2 of the temperature T1 of the first heat treatment and the temperature T2 of the second heat treatment may be approximately 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 approximately 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 is within a range lower than or equal to any of the upper limits described above; or within a range greater than or equal to any of the lower limits described above. Alternatively, it may be within a range that is less than or equal to any of the upper limits described above, and greater than or equal to any of the lower limits described above. Within this range, the alignment state of the hydrocarbon groups of the conductive polymer is appropriately controlled, and accordingly, the desired characteristics can be secured.

[0139] In the above case, the lower limit of the ratio H2 / H1 of the time H1 for the first heat treatment and the time H2 for the second heat treatment may be approximately 0.5, 1, 3, 5, 7, 9, 10, 11, 12, 13, 14, 14.5, or 15, and the upper limit may be approximately 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 is within a range equal to or less than any of the upper limits described above; or within a range equal to or greater than any of the lower limits described above. Alternatively, it may be within a range that is less than or equal to any of the upper limits described above, and greater than or equal to any of the lower limits described above. Within this range, the alignment state of the hydrocarbon groups of the conductive polymer is appropriately controlled, and accordingly, the desired characteristics can be secured.

[0140] In the above manufacturing process, a subsequent process such as an appropriate drying process may be additionally performed following the coating and / or polymerization process.

[0141] There are no particular limitations on the method of forming the active material layer on the polymer layer. Typically, the active material layer is formed by coating a slurry containing the electrode active material, binder, and conductive material onto a current collector (polymer layer), drying, and then rolling; such known methods can be applied in the present application as well.

[0142] The present specification also discloses an electrode assembly or electrochemical device, for example, a secondary battery, comprising the electrode described above. As long as the electrode assembly and electrochemical device include the electrode described above, there are no particular limitations on the specific details regarding other configurations. For example, the electrode assembly may include a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode as is known, wherein either or both of the positive electrode and the negative electrode may be the electrode described above. Furthermore, the electrochemical device, for example, a secondary battery, may include the electrode, or the electrode assembly and an electrolyte, etc. Effects of the invention

[0143] This specification discloses an electrode and its uses. The electrode comprises a polymer layer exhibiting a positive temperature coefficient (PTC) effect and oxidation potential controlled for a specific purpose. Under normal conditions, such an electrode exhibits excellent electrical characteristics, such as low resistance, thereby not affecting or even improving the performance and operation of a secondary battery, and under abnormal conditions, it can ensure stability. This specification also discloses the uses of the electrode. Brief explanation of the drawing

[0144] Figure 1 is a cross-sectional view of an exemplary electrode. Figure 2 is the result of NMR analysis of the monomer prepared in the preparation example. Figure 3 is the result of a performance evaluation for the electrode of Example 1. Figure 4 is the result of a performance evaluation for the electrode of Example 1. Figure 5 shows the performance evaluation results for the electrode of Comparative Example 1. Figure 6 shows the performance evaluation results for the electrode of Comparative Example 1. Specific details for implementing the invention

[0145] The electrodes, etc. disclosed in this specification will be specifically described through the following examples and comparative examples, but the scope of the electrodes, etc. is not limited by the following examples.

[0147] 1. NMR Analysis Method

[0148] 1 H-NMR analysis was performed at room temperature using an NMR spectrometer including a Bruker UltraShield spectrometer (300 MHz) equipped with a triple resonance 5 mm probe. The sample was diluted to a concentration of approximately 10 mg / ml in an NMR measurement solvent (CDCl3), and the chemical shift was expressed in ppm.

[0150] 2. GPC (Gel Permeation Chromatograph)

[0151] Molecular weight characteristics were measured using Gel Permeation Chromatography (GPC). The sample was placed in a 5 mL vial and diluted in chloroform to a concentration of approximately 1 mg / mL. Subsequently, the standard sample for calibration and the sample to be analyzed were filtered through a syringe filter (pore size: 0.45 μm) before measurement. Waters Empower 3 was used as the analysis program; the weight-average molecular weight (Mw) and number-average molecular weight (Mn) were determined by comparing the sample elution time with the calibration curve, and the molecular weight distribution (PDI) was calculated using the ratio (Mw / Mn). The GPC measurement conditions are as follows.

[0152] <GPC 측정 조건>

[0153] Device: Waters 2414

[0154] Column: 3 Waters Styragels used

[0155] Solvent: THF (Tetrahydrofuran)

[0156] Column temperature: 35℃

[0157] Sample concentration: 1 mg / mL, 1 μL injection

[0158] Standard Sample: Polystyrene (Mp: 3900000, 723000, 316500, 52200, 31400, 7200, 3940, 485)

[0160] 3. Thickness measurement

[0161] The thickness of the polymer layer, etc., was measured by taking a Scanning Electron Microscope (SEM) (JEOL, JSM-7200F) image after cross-sectioning the electrode using an ion milling machine (Hitachi, IM5000). The conditions for cross-section formation by the ion milling were set to cross-section milling mode, with the speed (reciprocation / min) set to 3, the acceleration voltage set to 6.0 kV, the discharge voltage set to 15 kV, the current set to 150 μA, and the time set to 4 hours.

[0163] 4. Oxidation Potential Measurement Method (Conductive Polymer / Polymer Layer)

[0164] The oxidation potential was measured in the following manner. A layer with a thickness of approximately 10 μm (hereinafter referred to as the polymer layer) was formed on an aluminum foil (Al Foil) with a thickness of approximately 15 μm using a conductive polymer to measure the oxidation potential. The polymer layer was formed by applying the same method as applied in Example 1 below.

[0165] Subsequently, a separator and a lithium film were laminated onto the polymer layer to produce a laminate having aluminum foil / polymer layer / separator / lithium film, and the laminate was die-cut into a circular shape with a diameter of approximately 1.4 cm. A coin cell was manufactured using the die-cut circular laminate and an electrolyte (using the Welcos CR2032 coin cell kit).

[0166] The WL20C model from W-Scope Korea was used as the separator, a lithium film with a thickness of about 100 μm was used, and as the electrolyte, a 1M LiPF6 solution (solvent: EC / DMC / EMC=3 / 4 / 3 (mass ratio), EC: Ethylene Carbonate, DMC: dimethyl carbonate, EMC: ethylmethyl carbonate) from Enchem was used.

[0167] The oxidation potential of the above coin cell was measured at 25°C using a potentiostat (Princeton Applied Research, PARASTAT-MC). The oxidation potential was measured by cyclic voltammetry (CV) in the range of 1.5 V to 5.5 V at a scan rate of 0.17 mV / sec to 0.5 mV / sec. The oxidation potential is the oxidation potential relative to lithium, and is calculated as the ratio of lithium to lithium ions (Li / Li + It was measured based on ).

[0169] 5. Oxidation Potential Measurement Method (Electrode Active Material)

[0170] The oxidation potential of the electrode active material was measured by manufacturing a coin cell using an electrode manufactured using the said electrode active material and measuring the coin cell.

[0171] A slurry was prepared by mixing the electrode active material to be measured, a conductive material (ECP (Ketjen Black) 0.5%, SFG (Trimrex graphite) 0.4%, DB (Denka Black) 0.4%), PVDF (poly(vinylidene fluoride)), and NMP (N-Methyl-2-pyrrolidone) in a weight ratio of 75:1:1:23 (electrode active material:conductive material:PVDF:NMP). The slurry was applied onto a current collector using a doctor blade, dried at room temperature (about 25°C), maintained in a drying oven at 130°C for about 30 minutes, and then rolled to form an electrode active material layer with a thickness of about 53 μm to manufacture the electrode.

[0172] The electrode active material to be measured was used as the above electrode active material.

[0173] The above rolling was performed so that the porosity of the active material layer was approximately 25%. The porosity of the active material layer is a value calculated by comparing the ratio of the difference between the actual density and the density after rolling, and a method of calculating porosity in this manner is known.

[0174] For the above-mentioned current collector, aluminum foil with a thickness of about 15 μm was used.

[0175] Subsequently, a separator and a lithium film were laminated onto the electrode active material layer of the electrode to produce a laminate having an electrode / separator / lithium film, and the laminate was die-cut into a circular shape with a diameter of approximately 1.4 cm. A coin cell was manufactured using the die-cut circular laminate and an electrolyte (using the Welcos CR2032 coin cell kit).

[0176] The WL20C model from W-Scope Korea was used as the separator, a lithium film with a thickness of about 100 μm was used, and as the electrolyte, a 1M LiPF6 solution (solvent: EC / DMC / EMC=3 / 4 / 3 (mass ratio), EC: Ethylene Carbonate, DMC: dimethyl carbonate, EMC: ethylmethyl carbonate) from Enchem was used.

[0177] The oxidation potential of the above coin cell was measured at 25°C using a potentiostat (Princeton Applied Research, PARASTAT-MC). The oxidation potential was measured by cyclic voltammetry (CV) at a scan rate of 0.17 mV / sec to 0.5 mV / sec in the range of 1.5 V to 5.5 V.

[0178] The above oxidation potential is an oxidation potential relative to lithium, where lithium and lithium ions (Li / Li + It was measured based on ).

[0180] 6. DC Resistance Measurement Method

[0181] DC resistance was evaluated using the same coin cell as used in "4. Oxidation potential measurement method (conductive polymer / polymer layer)" above. However, the thickness of the polymer layer in the coin cell was set to approximately 200 nm. A voltage of 4.3 eV was applied to the coin cell at room temperature (25℃) for 10 minutes, and the DC resistance was measured using a Fluke digital multimeter (FLUKE-87-5).

[0183] 7. Interface resistance (AC impedance resistance)

[0184] The interfacial resistance was evaluated using Electrochemical Impedance Spectronization (EIS) with the same coin cell used in "4. Oxidation Potential Measurement Method (Conductive Polymer / Polymer Layer)" above. However, the thickness of the polymer layer in the coin cell was set to approximately 200 nm. A voltage of 4.3 V was applied to the coin cell at room temperature (25°C) for 10 minutes, and the interfacial resistance obtained in the High Frequency region of the Nyquist plot obtained by the EIS measurement method at 50,000 Hz to 0.1 Hz was measured. An electrochemical potentiostat (Princeton Applied Research, PARASTAT-MC) was used as the EIS measurement instrument.

[0186] 8. Measurement of Maximum Rate of Change of Resistance (DC Resistance)

[0187] The maximum resistance change rate △R1 is determined according to the following Equation 1.

[0188] <Equation 1>

[0189] △R1 = Max{(Rn+5 / Rn) / 5}

[0190] The above △R1 is measured in the following manner.

[0191] A coin cell for measuring DC resistance (the coin cell applied in "6. DC Resistance Measurement Method" above) is placed in the center of a Convection Oven (JOTEK, OF3-05W), and the temperature of the oven 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 measuring multimeter (Fluke's digital multimeter (FLUKE-87-5)) located outside the oven to enable resistance measurement. Subsequently, the DC resistance is measured at each temperature while the temperature is increasing as set. That is, DC resistance is measured at 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, and 130℃, respectively. Each temperature is maintained for 1 minute according to the settings, and the DC resistance is measured at the point where 1 minute has elapsed at the corresponding temperature. The DC resistance at each temperature becomes Rn in Equation 1 above, and the DC resistance at a temperature 5℃ higher than the corresponding temperature becomes Rn+5 in Equation 1 above. 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 each denoted as Rn, and after calculating (Rn+5 / Rn) / 5 for 21 values ​​in the temperature range from 25℃ to 130℃, the maximum value among them is set as Max{(Rn+5 / Rn) / 5}(=△R1) of Equation 1 above, and the temperature n℃ at the maximum value (Rn+5 / Rn) / 5 is set as the On-Set temperature.

[0193] 9. Measurement of Maximum Rate of Resistance Change (AC Impedance)

[0194] The maximum resistance change rate △R2 is determined according to Equation 2 below.

[0195] <Equation 2>

[0196] △R2 = Max{(Rz+5 / Rz) / 5}

[0197] The above △R2 is measured in the following manner.

[0198] A coin cell for measuring AC impedance resistance (the coin cell applied in "7. Interface Resistance (AC Impedance Resistance)" above) is placed in the center of a Convection Oven (JOTEK, OF3-05W), and the temperature of the oven 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 outside the oven (the meter applied in "7. Interface Resistance (AC Impedance Resistance)" above) so that resistance measurement is possible. Then, the AC impedance resistance is measured at each temperature while increasing the temperature as set. That is, AC impedance resistance is measured at 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, and 130℃, respectively. Each temperature is maintained for 1 minute according to the settings, and the AC impedance resistance is measured at the point where 1 minute has elapsed at the corresponding temperature.

[0199] The AC impedance resistance at each temperature becomes Rz in Equation 2 above, and the AC impedance resistance at a temperature 5°C higher than the corresponding temperature becomes Rz+5 in Equation 2 above. 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 each set as Rz, and (Rz+5 / Rz) / 5 of 21 values ​​is calculated in the temperature range from 25℃ to 130℃, and the maximum value among them is set as Max{(Rz+5 / Rz) / 5}(=△R2) of Equation 2 above, and the temperature z℃ at the maximum value (Rz+5 / Rz) / 5 is set as the On-Set temperature.

[0200] The above AC impedance resistance was determined as the resistance obtained from the semicircle in the High Frequency region of the Nyquist plot obtained by the EIS measurement method at 50,000 Hz to 0.1 Hz after applying a voltage of 4.3 V for 10 minutes.

[0202] Preparation Example 1. Synthesis of monomer (A)

[0203] The monomer of the following chemical formula A was synthesized in the following manner.

[0204] [Chemical Formula A]

[0205]

[0206] 1.372 g (12.02 mmol, 1 eq) of 3-methoxythiophene and 3 g (16.83 mmol, 1.4 eq) of triethylene glycol monomethyl ether were dissolved in 100 ml of toluene with 230 mg of p-toluenesulfonic acid (p-TsOH) and mixed. The mixture was reacted under reflux at 120°C, and the methanol produced by transetherification was removed using a Type 4A molecular sieve packed with a Soxhlet extractor. After refluxing for 24 hours, the reaction mixture was quenched with water, extracted with ethyl acetate, washed with brine, and dried over magnesium sulfate (MgSO4). The solvent was removed using a rotary evaporator, and the residue was purified by column chromatography with a methylene chloride / hexane (2:1) elution to obtain the target compound (monomer (A)). The NMR analysis results for the target compound (monomer (A)) are shown in Fig. 2.

[0208] Preparation Example 2. Synthesis of a conductive polymer (polythiophene (A))

[0209] Polythiophene (A) was prepared by adding 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 the monomer (A) of Preparation Example 1 to a solution in which 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride was dissolved in 150 ml of methylene chloride, and polymerizing at 30°C for 24 hours. The molar ratio of the 3-dodecylthiophene unit (I), the 3-hexylthiophene unit (II), and the monomer (A) unit (III) of Preparation Example 1 in the conductive polymer (A) is approximately 3.94:1.97:0.66 (I:II:III).

[0210] After placing the polymerization solution in an osmotic membrane with a molecular weight of cut-off (MWCO) of 5000, it was immersed in 200 ml of acetonitrile solvent to remove unreacted iron chloride (III), monomers, and low molecular weight oligomers. The residue precipitated inside the osmotic membrane was washed with methanol and dried at 60°C for 12 hours to obtain polythiophene (A).

[0211] Polythiophene (A) had a weight-average molecular weight (Mw) and a number-average molecular weight (Mn) of 118,000 g / mol and 24,500 g / mol, respectively, and an oxidation potential of about 3.7 V.

[0213] Example 1.

[0214] An Al foil with a thickness of approximately 15 μm was used as a current collector. A coating solution was prepared by dispersing the polythiophene (A) of Preparation Example 2 in a solvent (chloroform) at a concentration of approximately 2.0 wt%. The coating solution was coated onto the current collector using a bar coating method. Subsequently, the current collector with the coating layer formed thereon was held in a drying oven at 140°C for approximately 4 minutes, and then held at 130°C for 1 hour to form a layer (polymer layer) with a thickness of approximately 200 nm.

[0215] Next, an active material layer was formed on the conductive polymer layer. The active material layer was formed using a slurry. The slurry was prepared by mixing a positive electrode active material, a conductive material (ECP (Ketjen Black) 0.5%, SFG (Trimrex graphite) 0.4%, DB (Denka Black) 0.4%), PVDF (poly(vinylidene fluoride)), and NMP (N-Methyl-2-pyrrolidone) in a weight ratio of 75:1:1:23 (electrode active material:conductive material:PVDF:NMP). The slurry was applied onto the conductive polymer layer using a doctor blade, dried at room temperature, maintained in a drying oven at 130°C for about 30 minutes, and then rolled to form an active material layer with a thickness of approximately 53 μm (based on an electrode active material weight of 0.03 g and a porosity of 18%).

[0216] As described above, LCO (LiCoO2) was used as the electrode active material, and the oxidation potential of the electrode active material measured in the manner described in "5. Oxidation potential measurement method (electrode active material)" was approximately 3.8V.

[0218] Comparative Example 1.

[0219] When forming an active material layer on a conductive polymer layer, as an electrode active material, NCM (Li[N 0.8 Co 0.1 Mn 0.1 An electrode was prepared in the same manner as in Example 1, except that O2) was used. The oxidation potential of the electrode active material (NCM), measured in the manner described in "5. Oxidation potential measurement method (electrode active material)" above, was approximately 3.7V.

[0221] Test Example 1. Charge / Discharge Test

[0222] Charge and discharge tests were performed by fabricating a coin cell. The coin cell was fabricated using a CR2032 standard coin cell kit (Welcos CR2032 coin cell kit). The electrode prepared in the example or comparative example was used as the positive electrode, and a lithium film (thickness: approximately 100 μm) was used as the negative electrode. As the electrolyte, a 1M LiPF6 solution (solvent: EC / DMC / EMC=3 / 4 / 3 (mass ratio), EC: Ethylene Carbonate, DMC: dimethyl carbonate, EMC: ethylmethyl carbonate) from Enchem was used, and as the separator, a PE (poly(ethylene)) separator (W-Scope Korea, WL20C model) was used.

[0223] A charge and discharge test was conducted using the above coin cell, and the test was performed for 6 cycles in the order of 0.1C charge / 0.1C discharge (1 cycle), 0.2C charge / 0.2C discharge (2 cycles), 0.5C charge / 0.1C discharge (3 cycles), 0.5C charge / 0.5C discharge (4 cycles), 0.5C charge / 1C discharge (5 cycles), and 0.5C charge / 2C discharge (6 cycles) using a constant current-constant voltage (CC-CV) method.

[0224] Figures 3 and 4 are charge-discharge curves performed on the electrode of Example 1, and Figures 5 and 6 are charge-discharge curves showing the results of a charge-discharge test performed using the electrode of Comparative Example 1.

[0225] In Figures 3 and 4, LCO(Ref) represents the charge-discharge curve in a charge-discharge test performed on an electrode manufactured in the same manner as Example 1 but without forming a conductive polymer layer, and LCO(SFL) represents the charge-discharge curve in a charge-discharge test performed on an electrode comprising a current collector layer, a conductive polymer layer, and an active material layer manufactured in Example 1.

[0226] In FIGS. 5 and 6, NCM(Ref) refers to the charge-discharge curve in a charge-discharge test performed on an electrode manufactured in the same manner as Comparative Example 1 but without forming a conductive polymer layer, and NCM(SFL) refers to the charge-discharge curve in a charge-discharge test performed on an electrode comprising a current collector layer, a conductive polymer layer, and an active material layer manufactured in Comparative Example 1.

[0227] From a comparison of the drawings, it can be seen that in the case of Example 1, where the oxidation potential of the conductive polymer in the conductive polymer layer (polymer layer) is lower than that of the electrode active material, the efficiency did not decrease even after charging and discharging, whereas in the case of Comparative Example 1, the efficiency of the coin cell decreased after charging and discharging.

[0229] Test Example 2. PTC Effect Test

[0230] The results of evaluating the DC resistance, interface resistance, △R1, the on-set temperature for △R1, △R2, and the on-set temperature for △R2 for the electrode of Example 1 among the electrodes manufactured above are as shown in Table 1 below.

[0231] In Table 1 below, Ref. is the result of manufacturing a coin cell that evaluates the DC resistance, interface resistance, △R1, the on-set temperature for △R1, △R2, and the on-set temperature for △R2, by changing only the conditions for the formation of the polymer layer and keeping other conditions the same as in Example 1.

[0232] That is, the result of Example 1 in Table 1 below is the result for a coin cell containing a polymer layer formed by coating a current collector (Al foil) with a coating solution prepared by dispersing the polythiophene (A) of Preparation Example 2 in a solvent (Chloroform) at a concentration of about 2.0 wt%, and maintaining the current collector with the coating layer formed thereon in a drying oven at 140°C for about 4 minutes, and then maintaining it at about 130°C for 1 hour, and Ref. is the result for a coin cell containing a polymer layer formed by coating the same coating solution as above on the same current collector (Al foil) with a bar coating solution, and maintaining the current collector with the coating layer formed thereon in a drying oven at 90°C for about 20 minutes.

[0233] Example 1 Ref. DC resistance (Ω·cm) 420 530 Interfacial resistance (Ω) 50 60 Equation 1 △R1 210 55 On set temperature (°C) 95 85 Equation 2 △R2 23.3 8.2 On set temperature (°C) 95 85

[0235] From Table 1, it can be seen that a positive temperature coefficient (PTC) effect designed for a specific purpose can be obtained through the application of a specific conductive polymer, and that even when the same conductive polymer is applied, the PTC effect can be additionally controlled depending on the formation method.

Claims

Claim 1 An electrode having a current collector; an active material layer formed on the current collector and comprising an electrode active material; and a polymer layer comprising a conductive polymer between the current collector and the active material layer, wherein the oxidation potential of the conductive polymer or polymer layer is lower than the oxidation potential of the electrode active material or active material layer, and △R1 ​​of Equation 2 below is 100 Ω·cm / ℃ or higher: [Equation 2] △R1 = Max{(R n+5 / R n R in Equation 2 ) / 5} n Silver is the DC resistance of the polymer layer at any one temperature n℃ within the range of 25℃ to 135℃, and R n+5 is the DC resistance of the polymer layer at a temperature 5°C higher than the above temperature n°C ((n+5)°C), and Max{(R n+5 / R n ) / 5} is (R confirmed within a temperature range of 25℃ to 135℃ n+5 / R n It is the maximum value among ) / 5 values. Claim 2 In claim 1, the electrode having an RV greater than 100 in the following Equation 1: [Equation 1] RV = 100 × Va / Vs. In Equation 1, Va is the oxidation potential of the electrode active material or active material layer, and Vs is the oxidation potential of the conductive polymer or polymer layer. Claim 3 In claim 2, an electrode in which the oxidation potential Va is within the range of 2V to 5V. Claim 4 In claim 2, an electrode in which the oxidation potential Vs is within the range of 0V to 5V. Claim 5 In claim 1, the polymer layer is an electrode having a DC resistance of 10,000 Ω·cm or less at 25°C. Claim 6 In claim 1, the polymer layer is an electrode having an AC impedance resistance of 1,000 Ω or less. Claim 7 delete Claim 8 An electrode according to claim 1, wherein the temperature at which △R1 of 100 Ω·cm / ℃ or more is confirmed is 80℃ or higher. Claim 9 ◈Claim 9 was abandoned upon payment of the registration fee.◈ In Claim 1, an electrode in which △R2 of the following Equation 3 is 10Ω / ℃ or greater: [Equation 3]△R2 = Max{(R z+5 / R z R in Equation 2 ) / 5} z is the AC impedance resistance of the polymer layer at any one temperature n℃ within the range of 25℃ to 135℃, and R z+5 is the AC impedance resistance of the polymer layer at a temperature 5°C higher than the above temperature n°C ((n+5)°C), and Max{(R z+5 / R z ) / 5} is (R confirmed within a temperature range of 25℃ to 135℃ z+5 / R z It is the maximum value among ) / 5 values. Claim 10 ◈Claim 10 was abandoned upon payment of the registration fee.◈ The electrode of Claim 9, wherein the temperature at which a △R2 of 10Ω / ℃ or more is confirmed is 80℃ or higher. Claim 11 In claim 1, the conductive polymer is an electrode that is polythiophene comprising thiophene units having hydrocarbon functional groups. Claim 12 In claim 11, the polythiophene is an electrode comprising, as thiophene units, a first thiophene unit having a hydrocarbon functional group having 10 or more carbon atoms and a second thiophene unit having a hydrocarbon functional group having 9 or fewer carbon atoms. Claim 13 In claim 11, the polythiophene is an electrode comprising 30 mol% or more of thiophene units having hydrocarbon functional groups. Claim 14 An electrode according to claim 12, wherein the ratio M2 / M1 of the moles of the second thiophene unit M2 to the moles of the first thiophene unit M1 is within the range of 0.01 to 100. Claim 15 In claim 11, the polythiophene is an electrode further comprising a thiophene unit having a polar functional group. Claim 16 In claim 15, the polythiophene is an electrode comprising thiophene units having hydrocarbon functional groups in an amount of 1 mole to 500 moles per mole of thiophene units having polar functional groups. Claim 17 An electrode assembly comprising an anode, a cathode, and a separator between the anode and the cathode, wherein the anode or the cathode is an electrode of any one of claims 1 to 6 and claims 8 to 16. Claim 18 A secondary battery comprising the electrode assembly of claim 17.

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