electrode

Abstract

Disclosed in the present specification are an electrode and use thereof. The electrode comprises a polymer layer, which exhibits a so-called positive temperature coefficient (PTC) effect at the required level when needed, and thus can be appropriately utilized in applications where stability is problematic due to abnormally high heat or flames. The polymer layer shows oxidation potential characteristics suitable for electrode use, and such oxidation potential characteristics can be stably maintained even under harsh environments. The polymer layer of the electrode can quickly exhibit the PTC effect when the PTC effect is needed. Disclosed in the present specification is also use of the electrode.

Description

electrode

[0001] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2023-0108455, dated August 18, 2023, the contents of which are incorporated herein by reference.

[0002] This specification discloses an electrode and its use.

[0003] Energy storage technology is expanding its application areas to include mobile phones, tablets, laptops, and even electric vehicles.

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

[0005] As major developed countries curb the production of vehicles powered by internal combustion engines to address global warming and air pollution, major automakers are also developing various electric vehicles. As such, the importance of secondary batteries with high energy density, high discharge voltage, and output stability as power sources is increasing.

[0006] In line with the above trend, the frequency of fire 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 these accidents is known to be a short circuit, which occurs when the positive and negative electrodes within the electrode assembly come into direct contact, primarily due to external stimuli. This short circuit can occur when a secondary battery is overcharged, exposed to high temperatures, or exposed to external stimuli, resulting in shrinkage of the separator due to an increase in the battery's internal temperature, or destruction of the battery's internal structure due to external impact.

[0008] When a short circuit occurs, the movement of lithium ions and electrons is concentrated at the point where the positive and negative electrodes are in direct contact, potentially accelerating internal heat generation. This is known to generate gases and other substances within the battery, causing its volume to expand and increasing the risk of fire.

[0009] The present specification discloses an electrode and its use. The purpose of the present specification is to disclose an electrode having a polymer layer that exhibits the so-called PTC (Positive Temperature Coefficient) effect at a required level at a required time, thereby ensuring stability in applications where stability due to abnormally high temperatures or flames is an issue. Another purpose of the present specification is to disclose an electrode comprising a polymer layer that exhibits oxidation potential characteristics suitable for the application and that stably maintains such oxidation potential characteristics even under harsh environments. Another purpose of the present specification is to disclose an electrode comprising a polymer layer that exhibits the PTC effect at a required level quickly at a required time. Another purpose of the present specification is to disclose uses of the electrode.

[0010] As used herein, the term "room temperature" refers to the natural temperature that has not been artificially heated or cooled. Room temperature may be, for example, any temperature within the range of 10°C to 30°C, or about 23°C, about 25°C, or about 27°C.

[0011] Among the properties mentioned in this specification, properties that are affected by the measurement temperature are properties measured at room temperature, unless otherwise specified.

[0012] The unit of temperature in this specification is Celsius (℃), unless otherwise specified.

[0013] In this specification, the term atmospheric pressure means natural pressure that has not been artificially pressurized or depressurized, and pressure within a range of about 730 mmHg to 790 mmHg can be generally regarded as atmospheric pressure.

[0014] Among the properties mentioned in this specification, properties that are affected by the measurement pressure are properties measured at atmospheric pressure, unless otherwise specified.

[0015] In this specification, the standard state humidity means any relative humidity within the range of 40% to 60%, and for example, a relative humidity of about 40%, 45%, 50%, 55% or 60% can be referred to as the standard state humidity.

[0016] Among the properties mentioned in this specification, properties that are affected by the measured humidity are properties measured at the humidity of the standard state, unless otherwise specified.

[0017] In this specification, the term normal state means the normal operating state (e.g., normal charging or discharging state of a secondary battery) and / or storage state of an electrical / electronic device such as a secondary battery.

[0018] The term "abnormal state" as used herein refers to a state in which abnormal heat generation, ignition, and / or explosion occurs in an electrical / electronic device such as a secondary battery, or a state in which the risk of such abnormal heat generation, ignition, and / or explosion increases. For example, a state in which abnormal heat generation, ignition, or explosion occurs in a secondary battery due to a short circuit phenomenon, or a dangerous state in which the risk of such heat generation, ignition, or explosion increases may be considered an abnormal state.

[0019] The present specification discloses an electrode.

[0020] The electrode may include a current collector and an electrode active material layer formed on the current collector. The electrode may additionally include a polymer layer between the current collector and the electrode active material layer. Fig. 1 is a cross-sectional schematic diagram of an electrode including a current collector (100), a polymer layer (200), and an electrode active material layer (300).

[0021] In the above electrode, the current collector (100) and the polymer layer (200), and the polymer layer (200) and the active material layer (300) may be in contact with each other. In some cases, other elements may exist between the current collector (100) and the polymer layer (200) or between the polymer layer (200) and the active material layer (300). In addition, although the drawing illustrates 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) present on both sides of the current collector (100) and the current collector (100), or may exist in one layer between either of the active material layers (300) present on both sides and the current collector (100).

[0022] The above electrode may be, for example, an anode or cathode applied to a secondary battery.

[0023] The polymer layer exhibits the so-called PTC (positive temperature coefficient) effect. Therefore, the polymer layer can variably control the movement of charges through the electrode depending on the temperature.

[0024] By applying such a polymer layer, the electrode can be applied to secondary batteries, etc., and exhibit excellent electrical characteristics including low resistance in a normal state, and can secure stability through an increase in resistance in an abnormal state.

[0025] In order for a polymer layer to be applied to an electrode and exhibit the above-described effect, the oxidation potential of the polymer layer and 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. The temperature at which the resistance increases due to the PTC effect and the resistance of the polymer layer before the resistance increase affect the performance of the secondary battery. For example, if the PTC effect is excessively expressed at the temperature in the above-described steady state, the performance of the secondary battery cannot be properly expressed before stability is secured. In addition, if the oxidation potential of the polymer layer is not appropriately controlled in relation to the electrode active material, there is a problem in that the performance of the battery, etc. in the steady state deteriorates.

[0026] The above polymer layer exhibits a PTC effect, and the oxidation potential of the polymer layer having the PTC effect and the PTC effect are controlled so that the performance of the secondary battery in a normal state does not affect the performance of the secondary battery, and stability can be secured in an abnormal state.

[0027] The conductive polymer, as described below, contains a relatively long-chain hydrocarbon functional group and a bithiophene monomer unit, etc., together with a thiophene monomer unit. By controlling the drying or annealing temperature in the process of forming a polymer layer including the conductive polymer and a conductive material, a suitable PTC effect (e.g., inducing an increase in resistance of the polymer layer at a desired temperature (the temperature of the ideal state of the battery)) can be secured.

[0028] In one example, the polymer layer applied to the electrode may have a lower oxidation potential than the electrode active material layer (or the electrode active material included in the electrode active material layer). The oxidation potential referred to herein is Li / Li unless otherwise specified. +It is a reference oxidation potential, which is measured in the manner described in the Examples section of this specification. The oxidation potential varies depending on the electrode and electrolyte applied for measurement, and in this specification, the oxidation potential is lithium and lithium ion (Li / Li + ) is the oxidation potential measured based on the standard.

[0029] The oxidation potential referred to in this specification is Li / Li + As a reference oxidation potential, it is measured by the method described in “4. Measurement of oxidation potential (polymer layer)” or “5. Measurement of oxidation potential (electrode active material)” in the Examples section of this specification.

[0030] In one example, the oxidation potential of the polymer layer can be controlled so that △V according to Equation 1 below is within a predetermined range in the above electrode.

[0031] [Formula 1]

[0032] △V = 100 × (Va - Vs) / Va

[0033] In Equation 1, Va is the oxidation potential of the active material layer or the electrode active material included therein, and Vs is the oxidation potential of the polymer layer.

[0034] The lower limit of △V in Equation 1 may be about 0%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, or 6%, and the upper limit may be about %, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, or 4.5%. The △V may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; or within a range that is equal to or less than any upper limit arbitrarily selected from the upper limits listed above and equal to or greater than any lower limit arbitrarily selected from the lower limits listed above. By controlling the oxidation potential of the polymer layer to satisfy the above relationship, a battery that operates stably and efficiently in a normal state can be provided.

[0035] The oxidation potential of the above polymer layer is not particularly limited as long as the above relationship is satisfied. The lower limit of the oxidation potential (Vs) of the polymer layer 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 6 V, 5.5 V, 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 within a range that is less than or equal to any one of the upper limits arbitrarily selected from the upper limits listed above; or within a range that is less than or equal to any one of the upper limits arbitrarily selected from the upper limits listed above and greater than or equal to any one of the lower limits arbitrarily selected from the lower limits listed above.

[0036] In one example, the polymer layer or the electrode to which the polymer layer is applied may have a DC resistance at 25°C below a certain level. Accordingly, stable operation or storage of the secondary battery may be possible under normal conditions. The upper limit of the DC resistance may be about 10,000, 9500, 9000, 8500, 8000, 7500, 7000, 6500, 6000, 5500, 5000, 4500, 4000, 3500, 3000, 2500, 2000, 1500, 1000, 950, 900, 850, 800, 750, 700, 650, 600, 550, 500, 450, 400, 350, 300, 250, 200, 150, 100, 90, 80, 70 or 60, and the lower limit may be about 5, It may be about 10, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550 or 600. The DC resistance may be within a range that is less than or equal to any one upper limit arbitrarily selected from the upper limits listed above; or within a range that is less than or equal to any one upper limit arbitrarily selected from the upper limits listed above and greater than or equal to any one lower limit arbitrarily selected from the lower limits listed above. The unit of the DC resistance is Ω·cm, and it is measured in the manner described in “6. DC resistance measurement method” of the Examples section of the present specification.

[0037] In one example, the polymer layer or the polymer layer electrode may have an AC impedance resistance at 25°C below a certain level. Accordingly, stable operation or storage of the secondary battery may be possible under normal conditions. The upper limit of the above AC impedance resistance may be about 1,000, 950, 900, 850, 800, 750, 700, 650, 600, 550, 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, 8 or 7, and the lower limit may be about 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10. The AC impedance resistance may be within a range that is less than or equal to an upper limit arbitrarily selected from the upper limits listed above; or within a range that is less than or equal to an upper limit arbitrarily selected from the upper limits listed above and greater than or equal to an lower limit arbitrarily selected from the lower limits listed above. The unit of the AC resistance is Ω, and it is measured in the manner described in “7. AC Impedance Resistance” of the Examples section of this specification.

[0038] By exhibiting the above DC resistance and / or AC impedance resistance, the secondary battery to which the above electrode is applied can be stably operated and stored in a normal state.

[0039] The above electrode is applied to a battery and exhibits increased resistance in an abnormal state, thereby blocking the current flow of the electrode assembly and ensuring stability.

[0040] The above polymer layer or the electrode to which the above polymer layer is applied can exhibit a characteristic in which △R1 of the following equation 2 is at a certain level or higher.

[0041] [Formula 2]

[0042] △R1 = Max{(R n+5 / R n ) / 5}

[0043] R in Equation 2 n is the 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 than the above temperature n℃ ((n+5)℃), 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.

[0044] The method for measuring △R1 of Equation 2 is described in the "8. Measurement of maximum resistance change rate (DC resistance)" section of the Examples section. In the method for checking the above △R1, 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 Wow R n Check. For example, if n is 90, R 95 / R 90 is the ratio of the DC resistance at 95°C to the DC resistance at 90°C. If △R1 is above a certain level at any temperature within the temperature range of 25°C to 135°C, it means that the resistance increases relatively rapidly at any temperature within the temperature range.

[0045] The lower limit of the above △R1 may be 10, 50, 100, 110, 120, 130, 140, 150, 160, 170, 180 or 190, and the upper limit may be 1,000, 950, 900, 850, 800, 750, 700, 650, 600, 550, 500, 450, 400, 350, 300, 250, 200, 190 or 180. The unit of the above △R1 is Ω·cm / ℃. The above △R1 is within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; Or, it may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0046] The temperature at which △R1 in the above range is confirmed, i.e. R in Equation 2 n The temperature may be in the range. The above temperature range is very important in terms of ensuring stable operation and stability of the secondary battery. That is, if the above temperature is in the normal temperature range of the secondary battery, a temperature increase at that temperature adversely affects the performance of the secondary battery. R in the above equation 2 n The lower limit of the temperature may be about 70℃, 75℃, 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 91℃, 92℃, 93℃, 94℃ or 95℃, and the upper limit may be about 200℃, 190℃, 180℃, 170℃, 160℃, 150℃, 140℃, 130℃, 120℃, 110℃, 100℃ or 90℃. The temperature is within a range that is greater than or equal to any one lower limit arbitrarily selected from the lower limits listed above; Or, it may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0047] By controlling the resistance increase within the above temperature range, stable operation and storage under normal conditions, as well as stable current conduction under abnormal conditions, can be achieved. For example, by adjusting the above temperature range, stable storage of secondary batteries is possible even when stored at relatively high temperatures.

[0048] The polymer layer, the current collector or electrode to which the polymer layer is applied, can exhibit a characteristic in which △R2 of the following equation 3 is at a certain level or higher.

[0049] [Formula 3]

[0050] △R2 = Max{(R z+5 / R z ) / 5}

[0051] R in Equation 3 z is the 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℃ higher than the above temperature n℃ ((n+5)℃), 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.

[0052] The method for measuring △R2 of the above equation 3 is described in the "9. Measurement of maximum resistance change rate (AC impedance)" section of the Examples section. In the method for confirming the above △R2, the initial temperature is 25°C and the final temperature is 135°C. The AC impedance resistance is measured at each temperature while increasing the temperature by 5°C from the initial temperature of 25°C. z+5 Wow R z Check. For example, if n is 90, R 95 / R 90is the ratio of the AC impedance resistance at 95°C to the AC impedance resistance at 90°C. An △R2 of 10 Ω / °C or more at any temperature within the temperature range of 25°C to 135°C means that the resistance of the polymer layer or electrode increases relatively rapidly at any temperature within the temperature range.

[0053] The lower limit of the above △R2 may be about 5, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, or 33, and the upper limit may be about 100, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, or 20. The unit of the above △R2 is Ω / ℃. The range of the above △R2 may be within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above; or within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above and less than or equal to any upper limit arbitrarily selected from the upper limits listed above.

[0054] By securing the above characteristics, it is possible to show an increase in resistance in an abnormal state, thereby blocking the current flow and ensuring stability.

[0055] As in the case of the equation, the temperature at which the above △R2 is confirmed, i.e. R zThe temperature range in is very important. The lower limit of the temperature may be about 70°C, 75°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C or 95°C, and the upper limit may be 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 is within a range that is greater than or equal to any one lower limit arbitrarily selected from the lower limits listed above; Or, it may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0056] By controlling the resistance increase within the above temperature range, stable operation and storage under normal conditions, as well as stable current conduction under abnormal conditions, can be achieved. For example, by adjusting the above temperature range, stable storage of secondary batteries is possible even when stored at relatively high temperatures.

[0057] The polymer layer, the current collector or electrode to which the polymer layer is applied, or the secondary battery to which the polymer layer is applied may exhibit characteristics in which the absolute value of △R3 in Equation 4 below is within a certain range.

[0058] [Formula 4]

[0059] △R3 = 100 × (C1-C2) / C1

[0060] In Equation 4, 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 4 are the discharge capacities measured for the coin cell using the polymer layer, and the specific method of measuring this is outlined in the examples.

[0061] The upper limit of the absolute value of △R3 in Equation 4 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%, 1%, or 0.5%, and the lower limit may be about 0%, 0.5%, or 1.5%. The absolute value of △R3 may be within a range that is less than or equal to any one upper limit arbitrarily selected from the upper limits listed above; or within a range that is equal to or greater than any one lower limit arbitrarily selected from the lower limits listed above, and less than or equal to any one upper limit arbitrarily selected from the upper limits listed above. △R3 in the above range means that the secondary battery can be operated and stored stably even when operated and stored at relatively high temperatures within the normal state range.

[0062] The polymer layer, the current collector or electrode to which the polymer layer is applied, or the secondary battery to which the polymer layer is applied may exhibit a characteristic in which the absolute value of △R4 in Equation 5 below is 50% or more.

[0063] [Formula 5]

[0064] △R4 = 100 × (C 25 -C 130 ) / C 25

[0065] In Equation 5, 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.

[0066] C1 and C3 in Equation 5 are the discharge capacities measured for the coin cell to which the polymer layer is applied, and the specific method of measuring this is summarized in 11. High-temperature discharge capacity reduction rate of the Examples.

[0067] The lower limit of the absolute value of △R4 in Equation 5 may be about 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86% or 88%, and the upper limit may be about 200%, 180%, 160%, 140%, 120%, 100%, 95%, 90%, 85% or 80%. The absolute value of △R4 is within a range that is equal to or greater than any one lower limit arbitrarily selected from the lower limits listed above; Or, it may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above. △R4 within the above range means that stability is effectively secured by an increase in resistance in an abnormal state of the secondary battery.

[0068] The above characteristics can be achieved by introducing a polymer layer as described below.

[0069] As the above current collector, one that is usually used as a current collector for a positive or negative electrode can be used.

[0070] As for the current collector, there are no particular limitations on its type, size, shape, etc., as long as it is conductive and does not cause chemical changes in an application device such as a secondary battery. Examples of materials that can be used as the current collector include copper, aluminum, stainless steel, nickel, titanium, or calcined carbon, or materials surface-treated with carbon, nickel, titanium, or silver on the surface of copper, aluminum, or stainless steel can be exemplified. The current collector may be in the form of a film, sheet, foil, net, porous body, foam, or non-woven body containing the material. 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.

[0071] Such a collector may have a thickness typically within the range of 3 μm to 500 μm, but is not limited thereto.

[0072] A polymer layer exists on one or both sides of the above-mentioned collector.

[0073] The term polymer layer refers to a layer containing a polymer. The lower limit of the content of the polymer in the polymer layer may be about 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 about 100 wt%, 95 wt%, 90 wt%, 85 wt%, 80 wt%, 75 wt%, 70 wt%, 65 wt%, 60 wt%, 55 wt% or 50 wt%. The content is the content of the polymer based on the total weight of the polymer layer. The content is within a range that is equal to or greater than any one lower limit arbitrarily selected from the lower limits listed above; Or, it may be a range that is less than or equal to an upper limit arbitrarily selected from the upper limits listed above, and greater than or equal to a lower limit arbitrarily selected from the lower limits listed above.

[0074] The polymer layer may not be a so-called electrode active material layer. The content of the electrode active material within the polymer layer may be controlled. For example, the upper limit of the content of the electrode active material within the polymer layer may be about 10 wt%, 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, 0.5 wt%, 0.1 wt%, 0.05 wt%, 0.01 wt%, 0.005 wt%, or 0.001 wt%, and the lower limit may be 0 wt%. The content is the content of the electrode active material based on the total weight of the polymer layer. The content may be within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above; or may be within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above, and greater than or equal to the lower limit described above.

[0075] The polymer layer may include a conductive polymer. As is well known, a conductive polymer is a polymer that exhibits conductivity due to a conjugated system and / or doping of a polymer chain. For example, the conductive polymer may be a polymer that exhibits low resistance in a doped state and high resistance in a de-doped state, and may be a polymer designed so that the transition between the doped and de-doped states can occur quickly at a necessary point in time in response to temperature and / or voltage.

[0076] The polymer layer may need to exhibit an appropriate level of oxidation potential depending on the intended use. For example, when the polymer layer is positioned between a current collector and an active material layer, as in the electrode, the polymer layer may need to exhibit a lower oxidation potential than the active material layer, and it is necessary that the low oxidation potential be maintained even during repeated charge / discharge and / or high-speed charge / discharge of the secondary battery. Otherwise, a potential drop phenomenon may occur during repeated charge / discharge and / or high-speed charge / discharge processes.

[0077] The thickness of the polymer layer can be appropriately controlled depending on the purpose. For example, the lower limit of the thickness of the polymer layer can be about 10 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm or 400 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 or 400 nm. The thickness can be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above and is equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0078] The conductive polymer included in the above polymer layer may be a thiophene polymer.

[0079] The term thiophene polymer refers to a polymer containing a certain level or more of thiophene monomer units.

[0080] For example, the lower limit of the ratio of the number of moles of thiophene monomer units in the thiophene polymer may be about 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol% or 80 mol%, and the upper limit may be about 100 mol%, 95 mol%, 90 mol% or 80 mol%. The ratio of the number of moles of the thiophene monomer units is the number of moles (M) of all monomer units present in the thiophene polymer or the number of moles (M) of all monomers applied to prepare the thiophene polymer. T ) or the ratio of the mole number (MT) of all thiophene monomers applied to prepare the above thiophene polymer (100×M T / M). The ratio of the above thiophene monomer unit (100×M T / M) may be within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above; or within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above and less than or equal to any upper limit arbitrarily selected from the upper limits listed above.

[0081] The term monomer unit refers to the form in which a monomer is polymerized and incorporated into a polymer. The term thiophene monomer refers to a monomer of the thiophene series, and includes a thiophene skeleton.

[0082] The above conductive polymer may include a long-chain hydrocarbon functional group or a monomer unit having the long-chain hydrocarbon functional group (hereinafter referred to as unit A). The unit A may be a thiophene monomer unit.

[0083] The term long-chain hydrocarbon functional group means a monovalent hydrocarbon group having a certain number of carbon atoms or a monovalent functional group containing the monovalent hydrocarbon group.

[0084] For example, the lower limit of the number of carbon atoms present in the long-chain hydrocarbon functional group (i.e., the number of carbon atoms of the monovalent hydrocarbon group) may be about 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, and the upper limit may be about 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, or 4. The above carbon number may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; or within a range that is equal to or less than any upper limit arbitrarily selected from the upper limits listed above and equal to or greater than any lower limit arbitrarily selected from the lower limits listed above.

[0085] The above carbon number may be the total number of carbons present in the long-chain hydrocarbon functional group, or the carbon number of the hydrocarbon chain of the straight-chain structure of the functional group. That is, the monovalent hydrocarbon group present in the long-chain hydrocarbon functional group may have a straight-chain or branched-chain structure. When the monovalent hydrocarbon group has a straight-chain structure, the carbon number of the straight-chain structure may be within the above range. When the monovalent hydrocarbon group has a branched-chain structure, the carbon number constituting the longest straight-chain chain in the branched-chain structure may be within the above range. For example, if the branched-chain structure is a 2-ethylhexyl group, the carbon number constituting the longest straight-chain chain is 6.

[0086] Examples of the long-chain hydrocarbon functional group include at least one selected from the group consisting of an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an alkylcarbonyl group, and an alkylcarbonyloxy group. In a suitable example, the long-chain hydrocarbon functional group may be an alkyl group and / or an alkoxy group.

[0087] 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 in the range of the number of carbon atoms present in the long-chain hydrocarbon functional group (i.e., the number of carbon atoms in the monovalent hydrocarbon group).

[0088] The above alkyl group, alkenyl group, alkynyl group, the above alkoxy group, the alkyl group of the alkylcarbonyl group, and the alkyl group of the alkylcarbonyloxy group may have a straight-chain or branched-chain structure. In the case of a branched chain, the number of carbon atoms constituting the longest straight chain in the branched chain structure may be within the above range.

[0089] The above long-chain hydrocarbon functional group, such as an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an alkylcarbonyl group or an alkylcarbonyloxy group, may be optionally substituted with one or more substituents.

[0090] Long-chain hydrocarbon functional groups can exhibit enhanced vibrational energy at elevated temperatures. This enhanced vibrational energy can affect the doping and dedoping states of conductive polymers. The degree of the vibrational energy and the temperature at which the vibrational energy appears are affected by the carbon number and arrangement state of the long-chain hydrocarbon functional group. Therefore, by adjusting the carbon number and amount of the long-chain hydrocarbon functional group and adjusting its arrangement state using the manufacturing method described below, the desired properties of the polymer layer can be secured. For example, at the same temperature, the vibrational energy of a relatively long chain is greater than that of a relatively short chain. Therefore, by appropriately employing long and short chains as the long-chain hydrocarbon functional group, a conductive polymer that satisfies the desired effect can be provided.

[0091] Additionally, the long-chain hydrocarbon functional group can provide appropriate mobility to a monomer or polymer during the polymerization process of a conductive polymer, thereby improving polymerization efficiency.

[0092] For example, the number of moles (M) of the long-chain hydrocarbon functional group relative to the number of moles (M) of the total monomer units of the conductive polymer L ) or the number of moles (M) of monomer units (unit A) having the above functional group L ) can be adjusted. For example, the lower limit of the ratio can be about 20 mol%, 25 mol%, 30 mol%, 35 mol%, 40 mol%, 45 mol%, 50 mol%, 55 mol%, 60 mol%, 65 mol% or 70 mol%, and the upper limit can be about 95 mol%, 90 mol%, 85 mol%, 80 mol% or 75 mol%. The ratio is the number of moles (M) of all long-chain hydrocarbon functional groups present in the conductive polymer relative to the number of moles (M) of all monomer units present in the conductive polymer or the number of moles (M) of all monomers applied to prepare the conductive polymer. L ) or the number of moles of monomer units having the long-chain hydrocarbon functional group (M L ) or the mole number (M) of monomers having all long-chain hydrocarbon functional groups applied to prepare the above thiophene polymer L ) ratio (100×M L / M). The ratio may be within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above; or within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above and greater than or equal to any lower limit arbitrarily selected from the lower limits listed above.

[0093] The conductive polymer may include a first hydrocarbon functional group and a second hydrocarbon functional group.

[0094] The first hydrocarbon functional group is a functional group having a relatively large number of carbon atoms among the long-chain hydrocarbon functional groups. The lower limit of the carbon atoms of the first hydrocarbon functional 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 carbon atoms of the first hydrocarbon functional group may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; or may be within a range that is equal to or less than any upper limit arbitrarily selected from the upper limits listed above and equal to or greater than any lower limit arbitrarily selected from the lower limits listed above.

[0095] The second hydrocarbon functional group is a functional group having a relatively small number of carbon atoms among the long-chain hydrocarbon functional groups. The lower limit of the carbon atoms of the second hydrocarbon functional group may be about 3, 4, 5, 6, 7, or 8, and the upper limit may be about 9, 8, 7, or 6. The carbon atoms of the second hydrocarbon functional group may be within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above; or within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above and greater than or equal to any lower limit arbitrarily selected from the lower limits listed above.

[0096] The number of carbon atoms in each of the first and second hydrocarbon functional groups may be the number of carbon atoms in a straight-chain hydrocarbon chain present in the hydrocarbon functional group. For example, the first and second hydrocarbon functional groups may each independently be at least one selected from the group consisting of an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an alkylcarbonyl group, and an alkylcarbonyloxy group, and may be an alkyl group and / or an alkoxy group in an appropriate example, and the number of carbon atoms may be the number of carbon atoms in the alkyl group, the alkenyl group, the alkynyl group, the alkoxy group, the alkyl group of the alkylcarbonyl group, and the alkyl group of the alkylcarbonyloxy group.

[0097] The above alkyl group, alkenyl group, alkynyl group, the above alkoxy group, the alkyl group of the alkylcarbonyl group and the alkyl group of the alkylcarbonyloxy group may have a straight-chain or branched-chain structure. In the case of a straight-chain structure, the total number of carbon atoms may be within the above range, and in the case of a branched-chain structure, the number of carbon atoms constituting the longest straight-chain chain in the branched-chain structure may be within the above range.

[0098] As described above, the carbon number of the long-chain hydrocarbon functional group is a functional group that exhibits enhanced vibrational energy at increased temperature, and the greater the carbon number at the same temperature, the higher the vibrational energy is exhibited. That is, the first hydrocarbon functional group exhibits higher vibrational energy than the second hydrocarbon functional group at the same temperature, and the sum of the vibrational energies of these two functional groups can optimize the properties of the conductive polymer, which are difficult to precisely control with a single functional group.

[0099] For example, the first hydrocarbon functional group exhibits enhanced vibrational energy at an increased temperature, and the second hydrocarbon functional group dilutes the vibrational energy of the first hydrocarbon functional group at the same temperature, thereby allowing the onset point of dedoping of the conductive polymer to be precisely controlled according to the purpose.

[0100] The ratio of the total mole number of the first and second hydrocarbon functional groups to the mole number (M) of the total monomer units of the conductive polymer or the total mole number of monomer units having the first hydrocarbon functional group and monomer units having the second hydrocarbon functional group is the ratio described above 100×M L / Can be adjusted within the same range as M.

[0101] The lower limit of the ratio (M2 / M1) of the number of moles (M2) of the second hydrocarbon functional group or the number of moles (M2) of the monomer unit having the second hydrocarbon functional group to the number of moles (M1) of the first hydrocarbon functional group or the number of moles (M1) of the monomer unit having the first hydrocarbon functional group may be about 0.01, 0.05, 0.1 or 0.5, and the upper limit may be 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 or 0.7. The above ratio may be within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above and greater than or equal to any lower limit arbitrarily selected from the lower limits listed above. The above ratio M2 / M1 may be changed taking into account the level of desired vibrational energy and the design value of the polymer layer.

[0102] The conductive polymer may include a polar functional group together with the long-chain hydrocarbon functional group. The monomer having the polar functional group may be a thiophene monomer.

[0103] The term polar functional group refers to a functional group containing one or more polar atoms, such as oxygen and / or nitrogen. Examples of such functional groups include, but are not limited to, a carboxyl group, a hydroxyl group, an amino group, a cyano group, a nitro group, an ether group, an alkoxy group, and / or a functional group represented by the following formula (1).

[0104] In the above, the alkoxy group may be, for example, an alkoxy 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 alkoxy group may be linear, branched, or cyclic, and may be linear or branched, as appropriate. The alkoxy group may be optionally substituted with one or more substituents.

[0105] In one example, the functional group of the following chemical formula 1 can be applied as the polar functional group.

[0106] [Chemical Formula 1]

[0107]

[0108] In chemical formula 1, L1 is a single bond, an alkylene group, or an alkylidene group, L2 is an alkylene group or an alkylidene group, R1 is hydrogen or an alkyl group, and m is any number.

[0109] In chemical formula 1, L1 being a single bond means that L1 does not exist and the oxygen atom between L1 and L2 is directly connected to the monomer.

[0110] The alkyl group of R1 in Chemical Formula 1 may be, in one 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 a methyl group or an ethyl group. The alkyl group may be linear, branched, or cyclic, and may be linear or branched, as appropriate. The alkyl group may be optionally substituted with one or more substituents.

[0111] The term alkylene group refers to a divalent functional group formed by the removal of one hydrogen atom from each of two different carbon atoms of 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 of an alkane.

[0112] The alkylene groups of L1 and L2 in Chemical Formula 1 may each be, in one example, 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, or an ethylene group or a propylene group. The alkylene group may be linear, branched, or cyclic, and may be linear or branched, as appropriate. The alkylene group may be optionally substituted with one or more substituents.

[0113] The alkylidene groups of L1 and L2 in the chemical formula 1 may each be, in one example, 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, or a methylidene group, an ethylylene group, or a propylidene group. The alkylidene group may be linear, branched, or cyclic, and may be linear or branched, as appropriate. The alkylidene group may be optionally substituted with one or more substituents.

[0114] In chemical formula 1, the lower limit of m may be 1, 2, 3, or 4, and the upper limit may be about 10, 9, 8, 7, 6, 5, 4, or 3. The n may be within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above, and greater than or equal to any lower limit arbitrarily selected from the lower limits listed above.

[0115] The polar functional group can bind the polymer layer to another layer with appropriate bonding strength, and in combination with the long-chain hydrocarbon functional group, can significantly improve the dispersibility of the conductive material described below within the polymer layer. In addition, the polar functional group can also play a role in suppressing the PTC effect from appearing at relatively low temperatures.

[0116] The mole numbers of the polar functional groups and long-chain hydrocarbon functional groups within the conductive polymer can be controlled to ensure an appropriate effect.

[0117] For example, the number of moles (M) of the long-chain hydrocarbon functional groups in the conductive polymer L ) or the number of moles (M) of monomer units having the long-chain hydrocarbon functional group L ) and the number of moles of the polar functional group (M P ) or the number of moles (M) of monomer units having the polar functional group P ) ratio (M L / M P ) may be about 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6 6.5, 7, 7.5, 8, 8.5 or 9, and its upper limit may be about 500, 450, 400, 350, 300, 250, 200, 150, 100, 90, 80, 70, 60, 50, 40, 30, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10 or 9.5. The above ratio M L / M P It may be within a range that is less than or equal to an upper limit arbitrarily selected from the upper limits listed above; or within a range that is greater than or equal to an lower limit arbitrarily selected from the lower limits listed above; or within a range that is less than or equal to an upper limit arbitrarily selected from the upper limits listed above and greater than or equal to an lower limit arbitrarily selected from the lower limits listed above. In the above, the ratio M L / M P If is the ratio between monomer units, the ratio is the number of moles M of monomer units having all long-chain hydrocarbon functional groups present in the conductive polymer. L and the number of moles M of monomer units having all polar functional groups P The ratio of; or the number of moles M of monomers having all long-chain hydrocarbon functional groups applied to prepare the conductive polymer L and the number of moles M of monomers having all polar functional groups P It can be a ratio of .

[0118] The total number of moles M of monomer units having the long-chain hydrocarbon functional group and monomer units having the polar functional group relative to the number of moles M of all monomer units in the conductive polymer S The ratio is 100×M as described above T / can be adjusted within the same range as M. At this time, the number of confiscations M T Instead, confiscate M S is substituted.

[0119] For example, the conductive polymer may include a unit of the following chemical formula 2 as the thiophene monomer unit.

[0120] [Chemical Formula 2]

[0121]

[0122] In Chemical Formula 2, R2 and R3 can each independently be hydrogen, the polar functional group, or the long-chain hydrocarbon functional group. In another example, R2 and R3 in Chemical Formula 2 can be linked to each other to form a divalent functional group of Chemical Formula 3 below.

[0123] [Chemical Formula 3]

[0124]

[0125] In chemical formula 3, L3 and L4 can each independently be a single bond, an alkylene group, or an alkylidene group, and R4 and R5 can each independently be hydrogen, the polar functional group, or the long-chain hydrocarbon functional group.

[0126] In the chemical formula 2, when R2 and R3 are each independently hydrogen, a polar functional group or a long-chain hydrocarbon functional group, at least one of R2 and R3 may be the polar functional group or the long-chain hydrocarbon functional group.

[0127] In the case where R2 and R3 in the chemical formula 2 form a divalent functional group of the chemical formula 3, at least one of R4 and R5 may be the polar functional group or long-chain hydrocarbon functional group.

[0128] In Chemical Formula 3, the meanings and specific examples of the single bond, alkylene group, and alkylidene group are the same as in Chemical Formula 1. In Chemical Formulas 2 and 3, the technical significance and specific examples of the long-chain hydrocarbon functional group and the polar functional group are as described above.

[0129] The number of moles M of the unit of the above chemical formula 2 compared to the number of moles M of the total monomer units of the conductive polymer C2 The ratio is 100×M above. T / M can be adjusted to the same extent, where M T Go M C2 is replaced by

[0130] In one example, the conductive polymer may include a monomer unit represented by the following chemical formula 4. The monomer unit of the chemical formula 4 may be an example of a monomer unit having the first hydrocarbon functional group.

[0131] [Chemical Formula 4]

[0132]

[0133] In chemical formula 4, R6 and R7 can each independently be hydrogen or the first hydrocarbon functional group. In this case, at least one of R6 and R7 can be the first hydrocarbon functional group.

[0134] In another example, R6 and R7 can be linked to each other to form a divalent functional group of the following chemical formula 5.

[0135] [Chemical Formula 5]

[0136]

[0137] In chemical formula 5, L5 and L6 are each independently a single bond, an alkylene group, or an alkylidene group, and R8 and R9 are each independently hydrogen or the first hydrocarbon functional group, but at least one of R8 and R9 may be the first hydrocarbon functional group.

[0138] The specific details of the first hydrocarbon functional group are as described above, and the specific details of the single bond, alkylene group or alkylidene group are as described in the chemical formula 1.

[0139] The conductive polymer may also include a monomer unit represented by the following chemical formula 6. The monomer unit of the chemical formula 6 may be an example of a monomer unit having the second hydrocarbon functional group.

[0140] [Chemical Formula 6]

[0141]

[0142] R in chemical formula 6 10 and R 11 Each of which may independently be hydrogen or the second hydrocarbon functional group, in which case R 10 and R 11 At least one of the above may be a second hydrocarbon functional group.

[0143] In another example, the above R 10 and R 11 can be linked to each other to form a divalent functional group of the following chemical formula 7.

[0144] [Chemical Formula 7]

[0145]

[0146] In chemical formula 7, L7 and L8 are each independently a single bond, an alkylene group or an alkylidene group, and R 12 and R 13 are each independently hydrogen or the second hydrocarbon functional group, R 12 and R 13 At least one of the above is a second hydrocarbon functional group.

[0147] The specific details of the second hydrocarbon functional group are as described above, and the specific details of the single bond, alkylene group, and alkylidene group are as described in Chemical Formula 1.

[0148] The conductive polymer may also include a monomer unit represented by the following chemical formula 8. The monomer unit of the chemical formula 8 may be an example of a monomer unit having the polar functional group.

[0149] [Chemical Formula 8]

[0150]

[0151] R in chemical formula 8 14 and R 15 Each of which can independently be hydrogen or the polar functional group. In the above case, the R 14 and R 15 At least one of the above polar functional groups.

[0152] In another example, R of the above chemical formula 8 14 and R 15 can be linked to each other to form a divalent functional group of the following chemical formula 9.

[0153] [Chemical Formula 9]

[0154]

[0155] In chemical formula 9, L9 and L 10 are each independently a single bond, an alkylene group or an alkylidene group, and R 16 and R 17 are each independently hydrogen or a polar functional group, R 16 and R 17 At least one of the above polar functional groups.

[0156] The specific details of the above polar functional group are as described above, and the specific details of the single bond, alkylene group, and alkylidene group are as described in Chemical Formula 1.

[0157] In the case where the conductive polymer simultaneously contains the monomer unit of the above chemical formula 4 and the monomer unit of the chemical formula 6, the total mole number M of the monomer unit of the above chemical formula 4 and the monomer unit of the chemical formula 6 is compared to the mole number M of the total monomer unit contained in the conductive polymer. 4+6 The ratio is 100×M as mentioned above. L / M can be adjusted within the same range, where M L This M 4+6 is replaced by

[0158] The ratio of the mole number M4 of the monomer unit of the above chemical formula 4 and the mole number M6 of the monomer unit of the above chemical formula 6 can be adjusted within the same range as the above ratio M2 / M1. At this time, the mole number M1 can be the mole number of the monomer unit of the above chemical formula 4, and the mole number M2 can be the mole number of the monomer unit of the above chemical formula 6.

[0159] When the conductive polymer contains monomer units of the above chemical formula 8, the units have a molar ratio M L / M P It can be included so that it is satisfied. At this time, the mole number of the monomer unit of the above chemical formula 8 is mole number M P becomes. In addition, the above confiscation M L It may be the number of moles of the monomer unit of the above chemical formula 4, the number of moles of the monomer unit of the above chemical formula 6, or the total number of moles of the monomer unit of the above chemical formula 4 and the monomer unit of the above chemical formula 6.

[0160] When the monomer units of the chemical formulae 4, 6 and 8 are present in the conductive polymer, the total mole number M of the monomer units of the chemical formulae 4, 6 and 8 4+6+8 The ratio of the total mole number M of all monomer units in the above conductive polymer is 100×M T / can be adjusted within the same range as M. At this time, the number of confiscations M 4+6+8 This confiscation M T It becomes.

[0161] The conductive polymer may contain the above monomer units and may additionally contain other monomer units. For example, the conductive polymer may contain a bithiophene monomer unit in addition to the thiophene monomer unit.

[0162] The above-mentioned bithiophene monomer unit is a unit of a monomer other than a thiophene monomer, and is a unit for adjusting the oxidation potential of the conductive polymer. For example, the above-mentioned bithiophene monomer unit may be a unit of a monomer that can be copolymerized with a thiophene monomer and exhibits a lower oxidation potential than polythiophene when manufactured as a homopolymer.

[0163] In the above case, the molar ratio of the thiophene monomer unit in the conductive polymer is 100×M T / M can be adjusted within the same range. In addition, the ratio of the bithiophene monomer unit can be adjusted in consideration of the desired oxidation potential.

[0164] For example, in the conductive polymer, the lower limit of the mole number of the bithiophene monomer unit per mole of the thiophene monomer unit may be about 0.05 mol, 0.1 mol, 0.15 mol, 0.2 mol, 0.22 mol, or 0.24 mol, and the upper limit may be about 1 mol, 0.9 mol, 0.8 mol, 0.7 mol, 0.6 mol, 0.5 mol, 0.4 mol, or 0.3 mol. The ratio may be within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above; or within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above; or within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above and greater than or equal to any lower limit arbitrarily selected from the lower limits listed above.

[0165] The above-mentioned bithiophene monomer unit may be, for example, an aromatic monomer unit or a nitrogen-containing heterocyclic monomer unit. The above-mentioned aromatic monomer unit is a unit formed from an aromatic monomer unit, and the nitrogen-containing heterocyclic monomer unit is a unit formed from a nitrogen-containing heterocyclic monomer.

[0166] For example, the bithiophene monomer unit may be a monomer unit of the following chemical formula 10.

[0167] [Chemical Formula 10]

[0168]

[0169] R in chemical formula 10 18 , R 19 and R 20 Each may independently be hydrogen, the polar functional group or the hydrocarbon functional group.

[0170] Examples of the above hydrocarbon functional group include an alkyl group, an alkenyl group, or an aryl group.

[0171] The above alkyl groups may each independently be alkyl groups having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms.

[0172] The above alkenyl group may be an alkenyl 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.

[0173] The aryl group may be, for example, an aryl group having 6 to 30 carbon atoms, or 6 to 26 carbon atoms, or 6 to 22 carbon atoms, or 6 to 20 carbon atoms, or 6 to 18 carbon atoms, or 6 to 15 carbon atoms.

[0174] The above alkyl group and alkenyl group may each independently be linear, branched, or cyclic. The above alkyl group, alkenyl group, and aryl group may each independently be optionally substituted with one or more substituents.

[0175] Specific details of the above polar functional group are as described above. For example, the unit of the above chemical formula 10 may be a polypyrrole unit.

[0176] In another example, the bithiophene monomer unit may be a unit of the following chemical formula 11.

[0177] [Chemical Formula 11]

[0178]

[0179] In chemical formula 11, L 11 is a single bond, alkylene group, alkylidene group, O or NR 1 It can be. The meaning of single bond, alkylene group or alkylidene group in the above is as described in chemical formula 1. In addition, the above R 1 may be hydrogen, an alkyl group, an alkenyl group, or an aryl group.

[0180] In chemical formula 11, R 21 Inland R 24 may each independently be hydrogen, an alkyl group, an alkenyl group, an amino group, an alkoxy group, an aryl group, or a halogen atom.

[0181] The specific types of alkyl groups, alkenyl groups, and aryl groups in Chemical Formula 11 are as described in Chemical Formula 10.

[0182] The alkoxy group of Chemical Formula 11 may be an alkoxy 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. Each of the alkoxy groups may independently be linear, branched, or cyclic. The alkoxy group may be optionally substituted with one or more substituents.

[0183] For example, the monomer unit of the above chemical formula 11 may be a polyaniline or polyphenylene monomer unit.

[0184] In another example, the bithiophene monomer unit may be a unit of the following chemical formula 12.

[0185] [Chemical Formula 12]

[0186]

[0187] In chemical formula 12, X1 is S, O or NR 1 It can be. Also, the above R 1 may be hydrogen, an alkyl group, an alkenyl group, or an aryl group.

[0188] In chemical formula 12, R 25 Inland R 28 Each of may independently be hydrogen, an alkyl group, an alkenyl group, an alkoxy group, an aryl group, or a halogen.

[0189] The specific types of alkyl group, alkenyl group, alkoxy group and aryl group in Chemical Formula 12 are the same as in Chemical Formulas 10 and 11. The monomer unit of Chemical Formula 12 may be a polyindole unit.

[0190] In another example, the bithiophene monomer unit may be a unit of the following chemical formula 13.

[0191] [Chemical Formula 13]

[0192]

[0193] In chemical formula 13, R 29 Inland R 34 Each can independently be hydrogen, an alkyl group, an alkenyl group, an alkoxy group, an aryl group, a hydroxy group, or a halogen. Specific types of the alkyl group, alkenyl group, alkoxy group, and aryl group of Chemical Formula 13 are as in Chemical Formulas 10 and 11 above.

[0194] The monomer unit of the above chemical formula 13 may be a polyazulene unit.

[0195] In another example, the bithiophene monomer unit may be a unit of the following chemical formula 14.

[0196] [Chemical Formula 14]

[0197]

[0198] In chemical formula 14, X2 is a carbon atom (CR a R b ) or nitrogen atom (NR 1 ) may be. In the above R a , R b and R 1 Each of may independently be hydrogen, an alkyl group, an alkenyl group, or an aryl group.

[0199] Meanwhile, the unit of the above chemical formula 14 may be unsubstituted or substituted with one or more selected from the group consisting of an alkyl group, an alkenyl group, an alkoxy group, an aryl group, and a halogen.

[0200] The specific types of alkyl group, alkenyl group, alkoxy group and aryl group in the above chemical formula 14 are the same as in the above chemical formulas 10 and 11.

[0201] For example, the monomer unit of the above chemical formula 14 may be a polyfluorene or polycarbazole unit.

[0202] In another example, the bithiophene monomer unit may be a unit of the following chemical formula 15.

[0203] [Chemical Formula 15]

[0204]

[0205] The unit of chemical formula 15 may be unsubstituted or substituted with one or more selected from the group consisting of an alkyl group, an alkenyl group, an alkoxy group, an aryl group, and a halogen.

[0206] The specific types of the alkyl group, alkenyl group, alkoxy group, and aryl group in the above chemical formula 15 are the same as in the above chemical formulas 10 and 11. For example, the monomer unit of the above chemical formula 15 may be a polypyrene unit.

[0207] The above conductive polymer may have a weight average molecular weight within a predetermined range. The lower limit of the weight average molecular weight of the above conductive polymer may be about 10,000, 15,000, 20,000, 25,000, 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, 65,000, 70,000, 75,000, 80,000, 85,000, 90,000 or 95,000, and the upper limit may be about 1,000,000, 950,000, 900,000, 850,000, 800,000, 750,000, 700,000, 650,000, It may be about 600,000, 550,000, 500,000, 450,000, 400,000, 350,000, 300,000, 250,000, 200,000, 150,000, 130,000, 110,000 or 100,000. The weight average molecular weight may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above and is equal to or less than any upper limit arbitrarily selected from the upper limits listed above. The unit of the weight average molecular weight is g / mol, and can be confirmed according to the description of "2. GPC (Gel Permeation Chromatograph)" in the Examples section of this specification.

[0208] 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) (Mw / Mn), may be within a predetermined range. The lower limit of the molecular weight distribution may be about 2, 2.5, 3, or 3.5, and the upper limit may be about 8, 7.5, 7, 6.5, 6, 5.5, 5, 4.5, 4, or 3.7. The molecular weight distribution may have a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above. The molecular weight distribution can be confirmed according to the description of "2. GPC (Gel Permeation Chromatograph)" in the Examples section of the present specification.

[0209] The conductive polymer may additionally contain other monomer units as long as they contain the aforementioned units in the above proportions.

[0210] The polymer layer comprises the conductive polymer and can thus exhibit the above-described properties. As long as the polymer layer comprises the conductive polymer, it can also comprise any additional components.

[0211] For example, the polymer layer may additionally include a conductive material along with the conductive polymer. By adding such a material, the oxidation potential of the polymer layer can be further controlled. As the conductive material, a material having appropriate conductivity can be used. For example, the conductive material may be one or more selected from carbon particles, carbon fibers, graphene, graphite, carbon black, and carbon nanotubes.

[0212] As the above-mentioned challenging material, an appropriate type may be selected and used from the types described above, and the form of the material may be, but is not limited to, a particle shape (spherical, irregular or other shape), a plate shape or a fiber shape.

[0213] The size of the above challenge material can also be appropriately adjusted as needed. For example, the lower limit of the size of the above-mentioned challenging material may be about 10 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm, 5000 nm or 10000 nm, and the upper limit may be about 100000 nm, 90000 nm, 80000 nm, 70000 nm, 60000 nm, 50000 nm, 40000 nm, 30000 nm, 20000 nm, 10000 nm, It may be about 5000 nm, 1000 nm, 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, 300 nm, 250 nm, 200 nm, 200 nm, 150 nm, 100 nm, 90 nm, 80 nm or 70 nm. The size may be within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above; or within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above; or within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above and greater than or equal to any lower limit arbitrarily selected from the lower limits listed above. The above size is the average diameter (so-called D50 particle diameter) measured according to the contents of the “12. Average particle diameter” item described in the Examples item of this specification.

[0214] If necessary, the above-mentioned challenging material may be surface-treated, taking into account dispersibility, etc.

[0215] In this case, a surface treatment agent having appropriate compatibility with the conductive polymer can be used as a surface treatment agent. For example, the conductive material may be surface-treated with a polyphenol-based compound as a surface treatment agent. A polyphenol-based compound refers to a compound having a structure containing two or more linked hydroxyl groups substituted on benzene. Examples of such compounds include so-called catechol-based compounds (i.e., catechol or compounds containing the structure), and examples thereof include, but are not limited to, dopamine, polydopamine, 3,4-dihydroxy phenyl alanine, norephinephrine, tannic acid, humic acid, and / or lignin.

[0216] There is no limitation on the method for surface treating a conductive material with the above surface treating agent, and for example, a method of mixing the conductive material and the surface treating agent in an appropriate solvent, etc., or a method of synthesizing or polymerizing the surface treating agent on the surface of the conductive material can be applied.

[0217] The content of the above-described conductive material can be adjusted in consideration of the desired oxidation potential. Generally, as the content of the conductive material in the polymer layer increases, the oxidation potential of the polymer layer decreases. Therefore, the content of the conductive material can be adjusted in consideration of the oxidation potential of the electrode active material and the corresponding oxidation potential of the polymer layer. For example, the lower limit of the content of the conductive material in the polymer layer relative to 100 parts by weight of the conductive polymer may be about 0.5 parts by weight, 1 part by weight, 5 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, 30 parts by weight, 40 parts by weight, 50 parts by weight, 60 parts by weight, 70 parts by weight, 80 parts by weight, 90 parts by weight or 100 parts by weight, and the upper limit may be about 1,000 parts by weight, 900 parts by weight, 800 parts by weight, 700 parts by weight, 600 parts by weight, 500 parts by weight, 400 parts by weight, 300 parts by weight, 200 parts by weight, 150 parts by weight, 100 parts by weight, 50 parts by weight, 48 parts by weight, 46 parts by weight, 44 parts by weight, 42 parts by weight, 40 parts by weight, 38 It can be about 36 parts by weight, 34 parts by weight, 32 parts by weight, 30 parts by weight, 28 parts by weight, 26 parts by weight, 24 parts by weight, 22 parts by weight, 20 parts by weight, 18 parts by weight, 16 parts by weight, 14 parts by weight, 12 parts by weight or 10 parts by weight. The content can be within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above; or within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above; or within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above and greater than or equal to any lower limit arbitrarily selected from the lower limits listed above.

[0218] Under such a ratio, the above-mentioned challenging material can appropriately interact with the above-mentioned conductive polymer to effectively form a polymer layer of the desired shape.

[0219] The above electrode may include an active material layer formed on the polymer layer. A commonly applied layer may also be used as the active material layer.

[0220] Typically, the above active material layer includes an electrode active material. There is no particular limitation on the specific type of the electrode active material, and typically, a material forming a positive or negative electrode can be used.

[0221] 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), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; lithium iron oxide such as LiFe3O4; or a compound having the chemical formula Li 1+c1 Mn 2-c1 Lithium manganese oxides such as O4(0≤c1≤0.33), LiMnO3, LiMn2O3, or LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, or Cu2V2O7; chemical formula LiNi 1-c2 M c2 Ni-site type lithium nickel oxide represented by O2 (wherein, M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, and satisfies 0.01≤c2≤0.3); chemical formula LiMn 2-c3 M c3 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, and satisfies 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); lithium nickel cobalt manganese (NCM) composite oxide, lithium nickel cobalt manganese aluminum (NCMA) composite oxide, and LiMn2O4 in which a part of Li in the chemical formula is replaced with an alkaline earth metal ion, but is not limited thereto.

[0222] When the above active material layer is a negative electrode active material layer, a compound capable of reversible intercalation and deintercalation of lithium may be used as the electrode active material. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; SiO a (0 < a < 2), metal oxides capable of doping and dedoping lithium, such as SnO2, vanadium oxide, and lithium vanadium oxide; or composites containing the above metal compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or a mixture of two or more of these may be used.

[0223] As the above negative active material, a lithium thin film may be used, and low-crystalline carbon and high-crystalline carbon may be used as carbon materials. Soft carbon and hard carbon are representative examples of low-crystalline carbon, and high-crystalline carbon is representative examples of amorphous, plate-like, flaky, spherical or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesocarbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch derived cokes.

[0224] The above electrode active material may be included in the active material layer in a range of about 80 wt% to 99.5 wt% or 88 wt% to 99 wt% relative to the total weight of the active material layer, but the ratio may be changed depending on the purpose or design of the electrode.

[0225] The above 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 binder are not particularly limited, and include, for example, PVDF (Poly(vinylidene fluoride)), PVA (poly(vinyl alcohol)), SBR (styrene butadiene rubber), PEO (poly(ethylene oxide)), CMC (carboxyl methyl cellulose), cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, cyanoethylpullulan, cyanoethyl polyvinylalcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, At least one selected from the group consisting of polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, and polyarylate may be used.

[0226] In one example, the binder may be included in the active material layer in an amount of 0.1 to 10 parts by weight or 0.5 to 5 parts by weight relative to 100 parts by weight of the electrode active material, but is not limited thereto.

[0227] The above active material layer may additionally include a conductive material, if necessary. As the conductive material, any known material may be used without particular limitation as long as it is conductive and does not cause 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, paneth black, lamp black, thermal black, etc.; conductive fibers such as carbon fiber or metal fiber; conductive tubes such as carbon nanotubes (CNTs); metal powders such as fluorocarbon, aluminum, and 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, etc. may be used.

[0228] The above-mentioned conductive material may be included in the active material layer in an amount of 0.1 to 20 parts by weight or 0.3 to 10 parts by weight relative to 100 parts by weight of the electrode active material, but is not limited thereto.

[0229] In addition to the components described above, the active material layer may additionally include any known components required.

[0230] As described above, in order for the polymer layer to exhibit the desired effect, selection of a long-chain hydrocarbon functional group and / or a conductive material is important, and furthermore, control of the arrangement state of the long-chain hydrocarbon functional group and / or the dispersion state of the conductive material is important. The desired arrangement and / or dispersion state can be secured by the manufacturing method described below.

[0231] The above manufacturing method may include a step of forming a polymer layer using a polymer solution containing the conductive polymer and, if necessary, the conductive material.

[0232] In the above step, the specific description of the conductive polymer used is as described above, and the coating solution can be prepared by dissolving the polymer in an appropriate solvent. At this time, the type of solvent is not particularly limited as long as it can dissolve at least a portion of the conductive polymer.

[0233] In the above step, the lower limit of the concentration of the conductive polymer present in the polymer solution may be about 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt% or 3 wt%, and the upper limit may be about 20 wt%, 18 wt%, 16 wt%, 14 wt%, 12 wt%, 10 wt%, 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5 wt%, 4 wt% or 3 wt%. The ratio may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, or within a range that is equal to or less than any upper limit arbitrarily selected from the upper limits listed above, or within a range that is equal to or less than any upper limit arbitrarily selected from the upper limits listed above and equal to or greater than any lower limit arbitrarily selected from the lower limits listed above. This concentration may be changed as needed.

[0234] The above conductive polymer can be formed by a known polymerization method. For example, representative methods for producing polythiophene include a method utilizing an oxidative polymerization reaction or a method utilizing a radical reaction.

[0235] The polymer solution is used to form a polymer layer on a current collector. This process typically includes the steps of coating the polymer solution on the current collector and heat-treating the coated coating solution. In this specification, the polymer layer formed on the current collector prior to the heat treatment may be referred to as a precursor. The crystallinity of the conductive polymer and the orientation of the long-chain hydrocarbon functional groups can also be controlled by the conditions of the heat treatment.

[0236] For example, the heat treatment step may be performed in two stages. For example, the heat treatment step may include a first stage of first heat treating the precursor at a temperature range T1; and a second stage of second heat treating the precursor at a temperature range T2 following the first stage.

[0237] The conditions of the first and second steps can be adjusted to achieve the desired orientation or alignment of the conductive polymer and the dispersion state of the conductive material.

[0238] For example, the temperature range T1 of the first heat treatment can be adjusted within a predetermined range. For example, the lower limit of the temperature range 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, 290°C, 280°C, 270°C, 260°C, 250°C, 240°C, 230°C, 220°C, 210°C, 200°C, 190°C, 180°C, 170°C, 160°C, 150°C or 140°C. The above temperature range T1 may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; or within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0239] In the above heat treatment step, the temperature range T1 of the first heat treatment and the temperature range T2 of the second heat treatment can be adjusted. For example, the lower limit of the ratio of the temperature ranges T1 and T2 can be about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, or 1.2, and the upper limit can be about 5, 4.5, 4, 3.5, 3, 2.5, 2, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, or 1.1. The ratio is within a range that is equal to or greater than any lower limit arbitrarily selected from the above-listed lower limits; or within a range that is equal to or less than any upper limit arbitrarily selected from the above-listed upper limits. Or, it may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0240] In one example, in the heat treatment step, the temperature range T1 of the first heat treatment can be adjusted to be higher than the temperature range T2 of the second heat treatment.

[0241] The ratio of the heat treatment time M1 in the first heat treatment and the heat treatment time M2 in the second heat treatment can be additionally adjusted. For example, the lower limit of the ratio M2 / M1 may be about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15, and the upper limit may be about 1,000, 950, 900, 850, 800, 750, 700, 650, 600, 550, 500, 450, 400, 350, 300, 290, 280, 270, 200, 150, 100, 90, 80, 70, 60, 50, 40, 30 or 20. The ratio M2 / M1 is within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above; Or within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above; or within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above and less than or equal to any upper limit arbitrarily selected from the upper limits listed above.

[0242] In the above, the lower limit of the secondary heat treatment time M2 may be about 0.1 hours, 0.2 hours, 0.3 hours, 0.4 hours, 0.5 hours, 0.6 hours, 0.7 hours, 0.8 hours, 0.9 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours or 18 hours, and the upper limit may be about 50 hours, 48 ​​hours, 46 hours, 44 hours, 42 hours, 40 hours, 38 hours, 36 hours, 34 hours, 32 hours, 30 hours, 28 hours, 26 hours, 24 hours, 22 hours, 20 hours, 18 The second heat treatment time M2 may be about 15 hours, 10 hours, 9 hours, 8 hours, 7 hours, 6 hours, 5 hours, 4 hours, 3 hours, 2 hours, or 1.5 hours. The second heat treatment time M2 may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; or within a range that is equal to or less than any upper limit arbitrarily selected from the upper limits listed above; or within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above and equal to or less than any upper limit arbitrarily selected from the upper limits listed above.

[0243] By the heat treatment as described above, the alignment state of the hydrocarbon functional groups of the conductive polymer is appropriately controlled, and accordingly, the desired effect can be obtained.

[0244] The method of coating the above coating solution is not particularly limited, and a known coating method can be applied.

[0245] Through the above process, the desired polymer layer and a current collector including the same are manufactured. The above process may include an appropriate post-processing process, if necessary.

[0246] The above manufacturing method may include a step of forming the active material layer on the polymer layer on the current collector. 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, a binder, a conductive agent, etc. on the current collector (polymer layer), drying it, and then rolling it. This known method can be equally applied.

[0247] The present specification also discloses an electrode assembly or electrochemical device comprising the above electrode, for example, a secondary battery.

[0248] The above-mentioned electrochemical device may include the electrode as an anode and / or cathode. As long as the electrode is used as an anode and / or cathode, other configurations or manufacturing methods of the electrochemical device are not particularly limited, and known methods may be applied.

[0249] The present specification discloses an electrode and its use. The electrode comprises a polymer layer that exhibits a so-called PTC (Positive Temperature Coefficient) effect at a required level at a required time, and thus can be suitably applied in applications where stability due to abnormally high temperatures or flames is a concern. The polymer layer exhibits oxidation potential characteristics suitable for the electrode application, and such oxidation potential characteristics can be stably maintained even under harsh environments. The polymer layer of the electrode can rapidly exhibit the PTC effect at a required time. The present specification also discloses uses of the electrode.

[0250] Figure 1 is a cross-sectional view of an exemplary electrode.

[0251] Figure 2 shows the NMR analysis results for the monomer of Manufacturing Example 1.

[0252] The electrodes and the like are specifically described through the following examples and comparative examples, but are not limited to the following examples of the electrodes and the like.

[0253]

[0254] 1. NMR analysis

[0255] 1 H-NMR analysis was performed at room temperature using a Bruker UltraShield spectrometer (300 MHz) equipped with a triple-resonance 5 mm probe. Samples were diluted in NMR solvent (CDCl3) to a concentration of approximately 10 mg / ml, and chemical shifts were expressed in ppm.

[0256]

[0257] 2. GPC (Gel Permeation Chromatograph)

[0258] Molecular weight characteristics were measured using gel permeation chromatography (GPC). The sample was placed in a 5 mL vial and diluted with chloroform to a concentration of approximately 1 mg / mL. The standard sample for calibration and the sample to be analyzed were filtered through a syringe filter (pore size: 0.45 μm), and then the molecular weight characteristics were measured. The analysis program used Waters' Empower 3, and the weight-average molecular weight (Mw) and number-average molecular weight (Mn) were obtained by comparing the elution time of the sample with the calibration curve, and the molecular weight distribution (PDI) was calculated as the ratio (Mw / Mn).

[0259] The measurement conditions of GPC are as follows.

[0260] <GPC 측정 조건>

[0261] Device: Waters 2414

[0262] Column: Using 3 Styragel from Waters

[0263] Solvent: THF (Tetrahydrofuran)

[0264] Column temperature: 35℃

[0265] Sample concentration: 1 mg / mL, 1 μL injection

[0266] Standard samples: Polystyrene (Mp: 3900000, 723000, 316500, 52200, 31400, 7200, 3940, 485)

[0267]

[0268] 3. Thickness measurement

[0269] The thickness of the polymer layer, etc., was measured by taking a SEM (Scanning Electron Microscope) (JEOL, JSM-7200F) image after cross-section processing using an ion milling device (Hitachi, IM5000). The conditions for cross-section formation by the ion milling were as follows: the device was set to cross-section milling mode, the speed (reciprocation / min) was 3, the acceleration voltage was 6.0 kV, the discharge voltage was 15 kV, the current was 150 μA, and the time was 4 hours.

[0270]

[0271] 4. Measurement of oxidation potential (polymer layer)

[0272] The oxidation potential was measured in the following manner. A polymer layer was formed to a thickness of approximately 10 μm using a conductive copolymer on an aluminum foil (Al Foil) having a thickness of approximately 15 μm. The polymer layer was formed in the same manner as described in each example or comparative example, and was formed to a thickness of approximately 10 μm. A separator and a lithium film were laminated on the polymer layer to manufacture a laminate in which aluminum foil / polymer layer / separator / lithium film were laminated, and the laminate was punched into a circle with a diameter of approximately 1.4 cm. A coin cell was manufactured using the laminate punched into a circle and the electrolyte (using the Welcos CR2032 coin cell kit). As the above separator, the WL20C model from W-Scope Korea was used, and as the lithium film, a lithium film with a thickness of approximately 100 μm was used, and as the electrolyte, a product from Enchem (1M LiPF6 solution (solvent: EC / DMC / EMC=3 / 4 / 3 (mass ratio), EC: Ethylene Carbonate, DMC: dimethyl carbonate, EMC: ethylmethyl carbonate)) was used.

[0273] 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 measuring CV (Cyclic Voltammetry) 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.

[0274]

[0275] 5. Measurement of oxidation potential (electrode active material)

[0276] The oxidation potential of the electrode active material was measured for a coin cell manufactured using an electrode manufactured using the electrode active material.

[0277] A slurry was prepared by mixing the electrode active material to be measured, 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 with a doctor blade, dried at room temperature (approximately 25°C), and then 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, thereby preparing an electrode. The rolling was performed so that the porosity of the active material layer was about 25%. The porosity of the above active material layer is a value calculated by comparing the ratio of the difference between the actual density and the density after rolling, and the method of calculating the porosity in this way is known. Aluminum foil with a thickness of approximately 15 μm was used as the current collector.

[0278] A separator and a lithium film were laminated on the electrode active material layer of the above electrode to manufacture a laminate in which electrode / separator / lithium film were laminated, and the laminate was stamped into a circle with a diameter of approximately 1.4 cm. A coin cell was manufactured using the laminate stamped into a circle and an electrolyte (using the Welcos CR2032 coin cell kit).

[0279] As the above separator, the WL20C model from W-Scope Korea was used, and as the lithium film, a film with a thickness of approximately 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.

[0280] The oxidation potential of the above coin cell was measured at 25°C using an electrochemical measuring instrument (potentiostat) (manufacturer: Princeton Applied Research, product name: PARASTAT-MC). The oxidation potential was measured by measuring CV (Cyclic Voltammetry) 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.

[0281] The above oxidation potential is Li / Li + It is measured based on .

[0282] Figure 2 shows NCM (Li[Ni) as an electrode active material. x Co (1-x) / 2 Mn (1-x) / 2 ]O2, x = 0.8) was applied to measure the oxidation potential. The oxidation potential of the electrode active material was approximately 3.7 V.

[0283]

[0284] 6. DC resistance measurement method

[0285] DC resistance was evaluated using the same coin cell used for oxidation potential measurements. 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).

[0286]

[0287] 7. AC impedance resistance

[0288] The AC impedance resistance was evaluated by Electrochemical Impedance Spectronization (EIS) 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 a Nyquist plot was obtained by EIS measurement from 50,000 Hz to 0.1 Hz, and the AC impedance resistance obtained in the high frequency region was measured. An electrochemical meter (potentiostat) (Princeton Applied Research, PARASTAT-MC) was used as the EIS measuring device.

[0289]

[0290] 8. Measurement of maximum resistance change rate (DC resistance)

[0291] The maximum resistance change rate △R1 is determined according to Equation 2 below.

[0292] <Formula 2>

[0293] △R1 = Max{(R n+5 / R n ) / 5}

[0294] R in Equation 2 n is the 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 than the above temperature n℃ ((n+5)℃).

[0295] The above △R1 is measured in the following manner.

[0296] A coin cell for measuring DC resistance is placed in the center of a convection oven (Jeotech, OF3-05W), and the temperature of the oven is set to an initial temperature of 25℃, a final temperature of 135℃, and an increase of 5℃ per minute. Connect the coin cell to a resistance measuring multimeter (Fluke's digital multi-tester (FLUKE-87-5)) outside the oven to enable resistance measurement. Then, as the temperature increases as set, the DC resistance is measured at each temperature (increasing the measurement temperature by 5℃ in the order of 25℃, 30℃, 35℃, and 40℃ and measuring up to 135℃). For each measurement temperature, R in Equation 1 n and R n+5 Measure each, R n+5 / R n (R 30 / R 25 , R 35 / R 30 ~ R 135 / R 130 ) and then divide it by 5 again.

[0297] In the temperature range of 25℃ to 135℃, the above (R n+5 / R n ) / 5 is obtained, and the maximum value among them is obtained as △R1. Through △R1, the temperature responsiveness of the resistance increase of the conductive copolymer (polymer layer) at the on-set temperature can be confirmed.

[0298] The above On-Set temperature is (R n+5 / R n ) / 5 is the temperature n℃ at which the maximum value is shown.

[0299] The coin cell used for the DC resistance measurement above was the same as that used for the oxidation potential measurement.

[0300]

[0301] 9. Measurement of maximum resistance change rate (AC impedance)

[0302] The maximum resistance change rate △R2 is determined according to Equation 3 below.

[0303] <Formula 3>

[0304] △R2 = Max{(R z+5 / R z ) / 5}

[0305] R in Equation 3 z is the AC impedance resistance at any temperature z℃ within the range of 25℃ to 135℃, and R z+5 is the AC impedance resistance at a temperature 5℃ higher than the above temperature z℃ ((z+5)℃).

[0306] The above △R2 is measured in the following manner.

[0307] The coin cell for AC impedance resistance measurement is placed in the center of a convection oven (Jeotech, OF3-05W), and the oven temperature is set to an initial temperature of 25℃, a final temperature of 135℃, and an increase of 5℃ per minute. The coin cell is connected to a resistance measuring device (potentiostat) (Princeton Applied Research, PARASTAT-MC) outside the oven to enable resistance measurement. Then, the AC impedance resistance is measured at each temperature (increasing the measurement temperature by 5℃ in the order of 25℃, 30℃, 35℃, and 40℃ until the measurement is made at 135℃) while the temperature increases as set. For each measurement temperature, R in Equation 2 z and R z+5 Measure each, R z+5 / R z (R 30 / R 25 , R 35 / R 30 ~ R 135 / R 130 ) and then divide it by 5 again.

[0308] In the temperature range of 25℃ to 135℃, the above (R z+5 / R z ) / 5, and then find the maximum value among them to obtain △R2.

[0309] Through the above △R2, the temperature responsiveness of the resistance increase of the conductive copolymer (polymer layer) at the on-set temperature can be confirmed.

[0310] The above On-Set temperature is (R z+5 / R z ) / 5 is the temperature n℃ at which the maximum value is shown.

[0311] The coin cell used for the above measurement was the same as that used for the oxidation potential measurement.

[0312] The above AC impedance resistance was obtained by applying a voltage of 4.3 V for 10 minutes, obtaining a Nyquist plot using the EIS measurement method from 50,000 Hz to 0.1 Hz, and taking the resistance obtained from the semicircle in the high frequency region.

[0313]

[0314] 10. Charge / Discharge Test

[0315] Charge and discharge tests were performed using coin cells. Coin cells were manufactured using a coin cell kit (Welcos CR2032 Coin Cell Kit) of the CR2032 standard. The electrodes manufactured in the examples or comparative examples were used as the positive electrode, and a lithium film (thickness: approximately 100 μm) was used as the negative electrode. The electrolyte was a product of Enchem, a 1M LiPF6 solution (solvent: EC / DMC / EMC=3 / 4 / 3 (mass ratio), EC: Ethylene Carbonate, DMC: dimethyl carbonate, EMC: ethylmethyl carbonate), and the separator was a PE (poly(ethylene)) separator (W-Scope Korea, WL20C model).

[0316] A charge / discharge test was conducted using the above coin cell, and the test was performed in a constant current-constant voltage (CC-CV) manner, and the charge / discharge conditions were 0.1C / 0.1C (condition 1), 0.5C / 0.1C (condition 2), 0.5C / 0.5C (condition 3), 0.5C / 1C (condition 4), and 0.5C / 2C (condition 5), respectively.

[0317]

[0318] 11. High temperature discharge capacity reduction rate

[0319] Coin cells were manufactured in the same manner as in the above charge / discharge tests.

[0320] For the above coin cell, one charge / discharge was performed at 25°C, and the capacity at 0.2C was calculated as the room temperature discharge capacity (C 25 ) was performed. One charge / discharge cycle is defined as one cycle in which the charging terminal voltage is set to 4.5 V and the charging terminal current is set to 1 mA, charging is performed in the CC (Constant Current) / CV (Constant Voltage) method at a rate of 0.2 C, and the discharging terminal voltage is set to 3.0 V and the discharging is performed in the CC (Constant Current) method at a rate of 0.2 C.

[0321] Meanwhile, after maintaining the coin cell at 130 for about 10 minutes, the high temperature discharge capacity (C 130 ) was obtained in the following manner. For the coin cell maintained at the high temperature, the charging end voltage was set to 4.5 V and the charging end current was set to 1 mA, and the charging was performed in the CC (Constant Current) / CV (Constant Voltage) method at a rate of 0.5 C, and then the discharge end voltage was set to 3.0 V and the discharging was performed in the CC (Constant Current) method at a rate of 2 C. This process was repeated 30 times, making one cycle, and the discharge capacity after 30 charge / discharge cycles was calculated as the high-temperature discharge capacity (C 130) was applied. The above 30 charge / discharge cycles were performed at 45°C.

[0322]

[0323] 12. Average particle size

[0324] The average particle diameter (D50 particle diameter) of the conductive particles was measured using a MASTERSIZER3000 from Marvern in accordance with the ISO-13320 standard. Toluene was used as the solvent during the measurement. When the sample (conductive particles) was dispersed in the solvent and a laser was irradiated, the laser was scattered by the sample dispersed in the solvent. Since the intensity and directionality of the scattered laser vary depending on the size of the particles, this can be analyzed using Mie theory to obtain the average particle diameter. Through the above analysis, the measurement results were converted into the particle diameter of a sphere having the same volume as the dispersed sample to obtain a volume-based cumulative graph of the particle size distribution, and the particle diameter at 50% of the cumulative point of the graph (median particle diameter) was designated as the average particle diameter (D50 particle diameter).

[0325]

[0326] Manufacturing Example 1. Synthesis of monomer (A)

[0327] The monomer of the following chemical formula A was synthesized in the following manner.

[0328] [Chemical Formula A]

[0329]

[0330] 3-Methoxythiophene 3 g (26.28 mmol, 1 eq) and triethylene glycol monomethyl ether 7.03 g (39.42 mmol, 1.5 eq) were dissolved in 150 ml of toluene and mixed with 500 mg of p-toluenesulfonic acid (p-TsOH) (2.63 mmol, 0.1 eq). The mixture was refluxed at 120°C under a nitrogen atmosphere, and the methanol produced by the reaction (transetherification) was removed with a 4A type molecular sieve packed in a soxhlet extractor. After refluxing for 24 h, the reaction mixture was cooled to room temperature, 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 using methylene chloride / hexane (2:1) elution to obtain the target compound (monomer (A)). The NMR analysis results for the monomer (A) are shown in Figure 2.

[0331]

[0332] Manufacturing Example 2. Synthesis of conductive polymer (A)

[0333] To a solution of 3.20 g (19.71 mmol, 3 eq) of iron(III) chloride dissolved in 150 ml of methylene chloride, 0.7 g (2.96 mmol, 0.6 eq) of 3-dodecylthiophene, 0.3 g (1.48 mmol, 0.3 eq) of 3-hexylthiophene, 0.12 g (0.49 mmol, 0.1 eq) of the monomer (A) of Preparation Example 1, and 0.37 g (1.23 mmol, 0.3 eq) of pyrrole were added, and polymerization was performed at 25°C for 24 hours to produce a conductive polymer (A). In the conductive polymer (A), the molar ratio of the 3-dodecylthiophene unit (I), the 3-hexylthiophene unit (II), the monomer (A) unit (III) of Preparation Example 2, and the pyrrole (IV) unit was approximately 2.96:1.48:0.49:1.23 (I:II:III:IV). The polymerization solution was placed in an osmotic membrane with a molecular weight of cut-off (MWCO) of 5000, and then immersed in 200 ml of acetonitrile to remove unreacted iron chloride and monomers. The residue precipitated inside the osmotic membrane was washed with methanol and dried at 60°C for 12 hours to obtain the conductive polymer (A). The weight average molecular weight (Mw) and number average molecular weight (Mn) of the above conductive polymer (A) were approximately 99,000 g / mol and 28,000 g / mol, respectively. The oxidation potential of the above conductive polymer was approximately 3.95 V (Li / Li + standard).

[0334]

[0335] Manufacturing Example 3. Polydopamine-coated challenge particles

[0336] As challenging particles, carbon black particles (IMERYS, C-NERGY TMSUPER C65) was used. The average particle diameter (D50 particle diameter) of the conductive particles was approximately 60 nm. Dopamine hydrochloride (CAS No. 62-31-7) was added to a buffer solution and stirred at room temperature (approximately 25°C). The buffer solution used was a 0.1M pH 8.5 Tris-buffer product from Biosesang Co., Ltd. The molar concentration of DHC in the final solution was approximately 2 mg / mL. The conductive particles were dispersed (sonicated for 1 hour) in a mixture of the buffer solution and DHC at a concentration of approximately 4 mg / mL and further stirred for approximately 18 hours to form a coating layer of polydopamine on the conductive particles. After filtering under reduced pressure using a paper filter, the conductive particles were vacuum-dried to obtain conductive particles coated with polydopamine.

[0337]

[0338] Example 1.

[0339] As a collector, Al foil with a thickness of approximately 15 μm was used.

[0340] The conductive polymer (A) of Manufacturing Example 2 and the conductive particles (P) of Manufacturing Example 3 were mixed in a weight ratio (A:P) of 8:2, and the mixture was dispersed in a solvent (chloroform) at a concentration of about 2 wt% to prepare a coating solution. The coating solution was coated on the current collector by bar coating, and after heat treatment (drying) at 140°C for about 4 minutes, heat treatment (annealing) was performed again at 130°C for about 1 hour to form a polymer layer having a thickness of about 300 nm.

[0341] The oxidation potential of the polymer layer was approximately 3.45 V when measured using the method described above.

[0342] An active material layer was formed on the polymer layer. The active material layer was formed by applying a slurry containing electrode active material, 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 (electrode active material: conductive material: PVDF: NMP) with a doctor blade to a thickness of about 90 μm on the polymer layer, drying at room temperature (about 25°C), and then further drying under vacuum conditions at 120°C. Subsequently, the electrode was manufactured by rolling so that the porosity was about 25%. As the electrode active material, NCM (Li[Ni x Co (1-x) / 2 Mn (1-x) / 2 ]O2, x = 0.8) (oxidation potential: approximately 3.7 V) was used.

[0343]

[0344] Example 2.

[0345] A polymer layer and electrode were manufactured in the same manner as in Example 1, except that a coating solution was manufactured by mixing the conductive polymer (A) of Manufacturing Example 2 and the conductive particles (P) of Manufacturing Example 3 in a weight ratio of 6:4 (A:P). The oxidation potential of the polymer layer was approximately 3.41 V as measured by the method described above.

[0346]

[0347] Example 3.

[0348] A polymer layer and an electrode were manufactured in the same manner as in Example 1, except that a coating solution was manufactured by mixing the conductive polymer (A) of Manufacturing Example 2 and the conductive particles (P) of Manufacturing Example 3 in a weight ratio of 5:5 (A:P). The oxidation potential of the polymer layer was approximately 3.37 V as measured by the method described above.

[0349]

[0350] Comparative Example 1.

[0351] An electrode was manufactured in the same manner as in Example 1, except that the polymer layer was not formed.

[0352]

[0353] Comparative Example 2.

[0354] A polymer layer and electrode were manufactured in the same manner as in Example 1, except that the coating solution was manufactured using only the conductive polymer (A) of Manufacturing Example 2 without using the conductive particles of Manufacturing Example 3. The oxidation potential of the polymer layer was approximately 3.72 V as measured by the method described above.

[0355]

[0356] For the electrode manufactured above, the oxidation potential (Vs) of the polymer layer (Li / Li + (Li / Li) oxidation potential (Va) of electrode active material (Li / Li) + The results of measuring the △V, DC resistance, AC impedance, and PTC effect are summarized in Table 1 below. The △V was calculated by the formula 100 × (Va - Vs) / Va (Va: oxidation potential of electrode active material, Vs: oxidation potential of polymer layer). In Table 1, the unit of oxidation potential is V.

[0357] Example Comparative Example 1 2 3 1 2 Vs 3.4 5 3.4 1 3.3 7-3.6 Va 3.7 3.7 3.7 3.7 3.7 △ V 6.8 7.8 8.9-2.7 DC resistance (Ω cm) 7 5 6 1 5 2 4.7 3 7 0 AC impedance (Ω) 1 0 7.2 6.2 1 .7 4 2 Formula 1 △ R 1 1 9 5 1 8 2 1 6 5 2.1 2 1 0 On set (℃) 9 5 1 0 0 9 5-9 5 Formula 2 △ R 2 1 9 1 8 1 1 7.4 2.8 2 2.7 On set (℃) 9 5 1 0 0 9 5-9 5

[0358] Table 2 below summarizes the capacity measured according to the above charge / discharge test conditions.

[0359] Example Comparative Example 12312 Condition 1 (0.1C / 0.1C) 219219.5220.1220.3217.7 Condition 2 (0.5C / 0.1C) 218.8219.6219.8220.1217.7 Condition 3 (0.5C / 0.5C) 197.0197.5197.8198.0194.3 Condition 4 (0.5C / 1C) 192.9193.6193.8194.0190.7 Condition 5 (0.5C / 2C) 186.4187.0187.4187.4179.2

[0360] From the results in Table 2, it can be confirmed that in the case of the example, the characteristics are at the same level as in Comparative Example 1, to which the polymer layer is not applied, but in the case of Comparative Example 2, to which the conductive particles are not applied and the oxidation potential is not adjusted in relation to the electrode active material, a potential drop occurs during discharge due to an increase in the C-rate.

[0361]

[0362] Table 3 below shows the room temperature discharge capacity C according to the high temperature discharge capacity reduction rate measurement method. 25 and high temperature discharge capacity C 130 is summarized. In Table 3, the reduction rate is 100×(C 25 -C 130 ) / C 25 It was calculated as follows.

[0363] Example Comparative Example 12312C25219.5220.0220.5221.3218.0C13022.539.046.5168.521.8Reduction Rate 89.782.378.923.990.0

[0364] Through Table 3, it can be confirmed that when the electrode according to the present application is applied, the rate of decrease in discharge capacity under high temperature conditions is high, and accordingly, stability can be secured in an abnormal state.

[0365] In the case of Comparative Example 2, a decrease in discharge capacity was confirmed under high temperature conditions, but the room temperature discharge capacity was lower than that of the example under the same conditions.

Claims

1. Whole house; An active material layer formed on the above-mentioned collector and including an electrode active material; and A polymer layer is present between the above-mentioned collector and the active material layer, and includes a conductive polymer and a conductive material. Li / Li of the above polymer layer + The reference oxidation potential is Li / Li of the above electrode active material. + Low electrode compared to reference oxidation potential.

2. In the first paragraph, an electrode having △V of more than 5% and less than 20% according to the following formula 1: [Formula 1] △V = 100 × (Va - Vs) / Va In Equation 1, Va is the Li / Li of the electrode active material. + is the reference oxidation potential, and Vs is Li / Li of the polymer layer. + This is the reference oxidation potential.

3. In the first paragraph, Li / Li of the polymer layer + An electrode having a reference oxidation potential of 5.0 V or less.

4. In the first paragraph, an electrode in which the absolute value of △R4 of the following equation 4 is 50% or more: [Formula 5] △R4 = 100 × (C1-C3) / C1 In Equation 5, C1 is the discharge capacity at 25°C, and C3 is the discharge capacity after 10 minutes of storage at 130°C.

5. In the first paragraph, the conductive polymer is an electrode having a long-chain hydrocarbon functional group.

6. In the fifth paragraph, the conductive polymer is an electrode comprising a first hydrocarbon functional group having 10 or more carbon atoms and a second hydrocarbon functional group having 9 or less carbon atoms as long-chain hydrocarbon functional groups.

7. In the first paragraph, the conductive polymer is an electrode including a functional group of the following chemical formula 1: [Chemical Formula 1] In chemical formula 1, L1 is a single bond, an alkylene group, or an alkylidene group, L2 is an alkylene group or an alkylidene group, R1 is hydrogen or an alkyl group, and m is a number in the range of 1 to 10.

8. In the first paragraph, the conductive polymer is an electrode comprising a thiophene monomer unit and a bithiophene monomer unit.

9. An electrode according to claim 8, wherein the bithiophene monomer unit is an aromatic monomer unit or a nitrogen-containing heterocyclic monomer unit.

10. An electrode in which the molar ratio of thiophene monomer units in the conductive polymer is 70 mol% or more, and 0.05 mol or more of bithiophene monomer units exist per mol of the thiophene monomer units in the 8th paragraph.

11. In the 8th paragraph, the bithiophene monomer unit is an electrode that is at least one unit selected from the group consisting of units of the following chemical formulas 10 to 15: [Chemical Formula 10] R in chemical formula 10 18 , R 19 and R 20 are each independently hydrogen, a polar functional group, or a hydrocarbon functional group: [Chemical Formula 11] In chemical formula 11, L 11 is a single bond, alkylene group, alkylidene group, O or NR 1 and the above R 1 is hydrogen, an alkyl group, an alkenyl group, or an aryl group: [Chemical Formula 12] In chemical formula 12, X1 is S, O or NR 1 and the above R 1 is hydrogen, an alkyl group, an alkenyl group, or an aryl group, and R 25 Inland R 28 are each independently hydrogen, an alkyl group, an alkenyl group, an alkoxy group, an aryl group, or a halogen: [Chemical Formula 13] In chemical formula 13, R 29 Inland R 34 are each independently hydrogen, an alkyl group, an alkenyl group, an alkoxy group, an aryl group, a hydroxy group, or a halogen: [Chemical Formula 14] In chemical formula 14, X2 is CR a R b or NR 1 and the above R a , R b and R 1 are each independently hydrogen, an alkyl group, an alkenyl group or an aryl group, and the unit of the above chemical formula 14 is unsubstituted or substituted with one or more selected from the group consisting of an alkyl group, an alkenyl group, an alkoxy group, an aryl group and a halogen: [Chemical Formula 15] The unit of chemical formula 15 is unsubstituted or substituted with one or more selected from the group consisting of an alkyl group, an alkenyl group, an alkoxy group, an aryl group, and a halogen.

12. An electrode according to claim 1, wherein the conductive material is carbon particles, carbon fibers, graphene, graphite, carbon black or carbon nanotubes.

13. In the first paragraph, the electrode is surface-treated with a polyphenol compound.

14. An electrode assembly comprising an electrode according to any one of claims 1 to 13.

15. A secondary battery comprising the electrode assembly of clause 14.

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