Electrode assembly

Abstract

The present specification discloses an electrode assembly and a secondary battery. The present specification discloses an electrode assembly formed by combining: an electrode which exhibits low resistance and excellent electrical characteristics in a normal state of a secondary battery, and in an abnormal state of the secondary battery, may be rapidly converted into an insulator so as to enable securing stability; and a separator which is referred to as a so-called safety-reinforcing separator (SRS). The present specification also discloses a secondary battery comprising the electrode assembly.

Description

electrode assembly

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0012285, filed January 26, 2024, and Korean Patent Application Nos. 10-2024-0030201, 10-2024-0030199, and 10-2024-0030196, filed February 29, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present specification discloses an electrode assembly and a secondary battery including the same.

[0003] The applications of secondary batteries (e.g., lithium ion batteries) are very diverse, including portable electronics, electric vehicles (EVs), and renewable energy storage systems.

[0004] Secondary batteries used as power sources in transportation devices such as electric vehicles require greater capacity and power.

[0005] The increased capacity and power of secondary batteries raise safety concerns. For example, the risk of so-called thermal runaway, which causes uncontrolled temperature increases and hazardous chemical leakage, increases with these increases in capacity and power.

[0006] Commercialized secondary batteries are equipped with external safety devices (such as pressure-limited valves, cell-to-cell fire extinguishers, or high thermal insulating materials), but these safety devices do not effectively respond to dangerous situations such as thermal runaway, or show slow response speeds.

[0007] The present specification discloses an electrode assembly and a secondary battery. The purpose of the present specification is to disclose an electrode assembly that combines an electrode that exhibits excellent electrical characteristics, including low resistance, under normal conditions and can rapidly convert to an insulator to ensure stability under abnormal conditions, with a separator, called a safety-reinforcing separator (SRS).

[0008] The present specification also discloses a secondary battery comprising the electrode assembly.

[0009] The term "room temperature" refers to the natural temperature, without artificial heating or cooling. Room temperature can be, for example, any temperature within the range of 10°C to 30°C, or about 23°C or about 25°C.

[0010] Among the properties mentioned in this specification, properties that are affected by the measurement temperature are properties measured at room temperature, unless otherwise specified.

[0011] In this specification, the unit of temperature is Celsius (℃) unless otherwise specified.

[0012] The term atmospheric pressure refers to natural pressure that has not been artificially pressurized or depressurized, and can usually mean a pressure within the range of about 730 mmHg to 790 mmHg.

[0013] Among the properties mentioned in this specification, properties that are affected by the measurement pressure are properties measured at atmospheric pressure, unless otherwise specified.

[0014] Among the properties mentioned in this specification, properties affected by measured humidity are properties measured at room temperature and pressure and at humidity that is not artificially controlled, unless otherwise specified.

[0015] The term "normal state" refers to the normal operating or storage state of a secondary battery. For example, the normal charging, discharging, or storage state of a secondary battery is the normal state.

[0016] The term abnormal condition refers to a hazardous condition in which an abnormal temperature rise, overheating, or explosion has occurred or may occur in secondary batteries, etc.

[0017] The present specification discloses an electrode assembly.

[0018] The electrode assembly includes a cathode; an anode; and a separator. The separator may be present between the anode and the cathode. In the electrode assembly, the anode, the separator, and the cathode may be stacked in the above order to form a laminate.

[0019] Figure 1 is an example of the above laminate, in which a positive electrode (C), a separator (S), and a negative electrode (A) are sequentially laminated.

[0020] The separator applied to the above electrode assembly may be a separator called a so-called safety-reinforcing separator (SRS).

[0021] SRS is a membrane comprising an inorganic particle layer on the surface of a membrane substrate (porous polymer membrane). Compared to conventional membranes, it exhibits stability and maintains performance at higher temperatures. When combined with an electrode containing a polymer layer, described below, this membrane's stability can be significantly improved.

[0022] These SRSs are well known.

[0023] Such an SRS may include, for example, a porous polymer film (100) and an inorganic particle layer (200) as shown in FIG. 2. In the form of FIG. 2, the inorganic particle layer (200) is formed on one side of the polymer film (100), but the inorganic particle layer (200) may also be formed on both sides of the polymer film (100).

[0024] As a porous polymer membrane, a polymer membrane typically used in SRS can be used. For example, a material that facilitates lithium ion movement and exhibits excellent electrolyte absorption capacity can be used.

[0025] In one example, a polyolefin-based polymer membrane can be used as the porous polymer membrane.

[0026] Polyolefin polymer membranes that can be used as porous polymer membranes in SRS are known in the industry, and for example, a porous polymer membrane manufactured from any one or a combination of two or more selected from the group consisting of polyethylene such as high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and ultra-high molecular weight polyethylene; polypropylene; polybutylene; polypentene; polyhexene; polyoctene; and copolymers containing two or more monomer units selected from the group consisting of ethylene, propylene, butene, pentene, 4-methylpentene, hexene, and octene can be applied.

[0027] These porous polymer films typically have a thickness of about 1 μm to 100 μm or 5 μm to 50 μm. These porous polymer films typically have pores with a size of about 0.001 μm to 50 μm, and the porosity is typically adjusted within a range of 10% to 95%.

[0028] SRS includes an inorganic particle layer formed on one or both sides of the porous polymer membrane. The term inorganic particle layer refers to a layer containing inorganic particles.

[0029] The above inorganic particles are used in the operating voltage range of electrochemical devices such as secondary batteries (e.g., Li / Li). + It is possible to use materials that do not undergo oxidation and reduction reactions within a range of 0 V to 5 V (as a reference), and inorganic particles with ion transfer capabilities can also be used. For example, applying inorganic particles with a high dielectric constant can contribute to increasing the degree of dissociation of electrolyte salts, such as lithium salts, in the electrolyte, thereby improving the ionic conductivity of the electrolyte.

[0030] For example, the inorganic particles may be inorganic particles having a dielectric constant of 5 or more and / or inorganic particles having lithium ion transfer capability.

[0031] Examples of these inorganic particles include BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg3Nb 2 / 3 )O 3- One or more inorganic particles selected from the group consisting of PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2 and SiC; and / or Li3PO4, Li x Ti y (PO4)3(0 <x<2, 0<y<3), Li x Al y Ti z (PO4)3(0 <x<2, 0<y<1, 0<z<3) 및 / 또는 14Li2O-9Al2O 3- 38TiO 2- (LiAlTiP) such as 39P2O5 x O y (0 <x<4, 0<y<13) 계열의 glass, Li x La y TiO3(0 <x<2, 0<y<3) 및 / 또는 Li 3.25 Ge 0.25 P 0.75Li such as S4 x Ge y P z S w (0 <x<4, 0<y<1, 0<z<1, 0<w<5) 및 / 또는 Li3PO 4- SiS2 series glass (Li, such as Li2S-SiS2) x Si y S z , 0 <x<3, 0<y<2, 0<z<4) 및 / 또는 LiI-Li2S-P2S5등과 같은 P2S5계열의 glass (Li x P y S z , 0 <x<3, 0<y<3, 0<z<7)로 이루어진 군으로부터 선택된 1종 이상의 무기 입자가 사용될 수 있다.

[0032] These inorganic particles typically have a size within the range of 0.001 μm to 10 μm. The size of these inorganic particles can be measured in the manner described in “15. Average Particle Diameter” of the Examples section of this specification.

[0033] In the SRS, the inorganic particle layer may include a polymer binder together with the inorganic particles. These polymer binders typically include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, Cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer and / or polyimide are used, and one type or a mixture of two or more types of these binders may be used.

[0034] The content of the inorganic particles in the inorganic particle layer is about 10 wt% to 95 wt%, 30 wt% to 95 wt%, 50 wt% to 95 wt%, or 70 wt% to 90 wt%, and the binder, when included, may be included in a ratio of about 5 to 100 parts by weight or about 10 to 50 parts by weight relative to 100 parts by weight of the inorganic particles.

[0035] The inorganic particle layer may additionally include known components required in addition to the binder, for example, organic particles for promoting bonding with the binder polymer and improving breathability, heat shrinkage, and peel strength.

[0036] The inorganic particle layer can typically have a thickness of about 0.1 μm to 50 μm or about 1 μm to 10 μm. The method for manufacturing the SRS is known, and the inorganic particle layer can be formed through such known methods.

[0037] The electrode assembly includes an anode and a cathode together with the separator.

[0038] The positive and negative electrodes each include a current collector and an electrode active material layer formed on one or both sides of the current collector.

[0039] Either or both of the positive and negative electrodes may include, for example, a polymer layer. FIG. 3 is an example of an electrode structure including a polymer layer. When a polymer layer is included, the polymer layer (1002) may be present between the current collector (1001) and the active material layer (1003) of the positive and / or negative electrodes.

[0040] For example, when the positive electrode includes the polymer layer, the positive electrode may include a current collector; a polymer layer formed on the current collector; and an active material layer formed on the polymer layer.

[0041] In the electrode, the current collector and the polymer layer, and the polymer layer and the active material layer may be in contact with each other. In some cases, other elements may exist between the current collector and the polymer layer or between the polymer layer and the active material layer. In Fig. 3, the active material layer (1003) exists only on one side of the current collector (1001), but the active material layer (1003) may exist on both sides of the current collector (1001). In this case, the polymer layer (1002) may exist in two layers between each of the active material layers (1003) present on both sides of the current collector (1001) and the current collector (1001), or may exist in one layer between any one of the active material layers (1003) present on both sides and the current collector (1001).

[0042] 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.

[0043] By applying such a polymer layer, the electrode can exhibit low resistance and excellent electrical characteristics in a normal state, and can secure stability through an increase in resistance in an abnormal state.

[0044] In order for the polymer layer to exhibit the above 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. If the PTC effect is excessively expressed in the 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.

[0045] The polymer layer disclosed in this specification has a PTC effect, and the oxidation potential of the polymer layer having this PTC effect and the PTC effect are controlled so that the performance of the secondary battery in a normal state does not affect it, and stability can be secured in an abnormal state.

[0046] The above effects can be achieved by applying a conductive polymer having long-chain hydrocarbon functional groups and / or polar functional groups. If necessary, a suitable PTC effect can be achieved by controlling the drying or annealing temperature during the polymer layer formation process. Furthermore, the oxidation potential of the polymer layer can be adjusted by combining the conductive polymer described above with a conductive material.

[0047] The term polymer layer refers to a layer containing a polymer. For example, the lower limit of the content of the polymer contained in the polymer layer may be about 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 or 95, and the upper limit may be about 100, 95, 90, 85, 80, 75, 70, 65, 60, 55 or 50. The content is the content of the polymer based on the total weight of the polymer layer, and the unit is weight%. The content 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.

[0048] The polymer layer may not be a so-called active material layer of the electrode. Accordingly, 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, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5, 0.1, 0.05, 0.01, 0.005, or 0.001, and the lower limit may be 0. The content is the content of the electrode active material based on the total weight of the polymer layer, and the unit is weight%. 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 any lower limit arbitrarily selected from the lower limits listed above. Specific types of the electrode active material will be described later.

[0049] The above polymer layer may include a conductive polymer. As is known, a conductive polymer is a polymer that exhibits conductivity due to a conjugated system and / or doping of a polymer chain.

[0050] For example, the lower limit of the content of the conductive polymer included in the polymer layer may be about 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 or 95, and the upper limit may be about 100, 95, 90, 85, 80, 75, 70, 65, 60, 55 or 50. The content is the content of the conductive polymer based on the total weight of the polymer layer, and the unit is weight%. The content 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.

[0051] The oxidation potential characteristics of the polymer layer can be adjusted according to the application. For example, the oxidation potential of the polymer layer needs to be stably maintained even when repeated charging and discharging or rapid charging and discharging are performed for a secondary battery to which the electrode is applied. By using a conductive polymer, introducing a conductive material, and / or adjusting the heat treatment conditions for the polymer layer, which will be described later, the target oxidation potential can be stably maintained even during repeated charging and discharging and rapid charging and discharging.

[0052] For example, the absolute value of △V1 of the above polymer layer in Equation 1 below may be within a predetermined range.

[0053] [Formula 1]

[0054] △V1= 100×(V f- V i ) / V i

[0055] V in Equation 1 i is the oxidation potential after one cyclic voltammetry of the polymer layer, and V f is the oxidation potential after 10 cyclic voltammetry of the above polymer layer.

[0056] Oxidation potential V of Equation 1 i and V f is the oxidation potential measured for the coin cell to which the polymer layer is applied, and "12. Oxidation potential V" of the example item of the present specification i and V f The results are measured in the manner described in “Measurement of Li / Li”. + This is the reference oxidation potential.

[0057] The upper limit of the absolute value of △V1 in Equation 1 may be about 3%, 2.9%, 2.8%, 2.7%, 2.6%, 2.5%, 2.4%, 2.3%, 2.2%, 2.1%, 2.0%, 1.9%, 1.8%, 1.7%, 1.6%, 1.5%, 1.4%, 1.3%, 1.2%, 1.1%, 1.0%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, or 0.4%, and the lower limit may be about 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, or 1%. The above △V1 may be within a range that is less than or equal to an upper limit arbitrarily selected from the upper limits listed above; or may be within a range that is greater than or equal to an upper limit arbitrarily selected from the lower limits listed above and less than or equal to an upper limit arbitrarily selected from the upper limits listed above.

[0058] Oxidation potential V of Equation 1 i The oxidation potential can be adjusted depending on the application of the polymer layer. The oxidation potential can be adjusted by adjusting the type of conductive polymer and / or the content of the conductive material.

[0059] Oxidation potential V of Equation 1 i The upper limit of the oxidation potential V may be about 4.0 V, 3.95 V, 3.9 V, 3.85 V, 3.8 V, 3.75 V, 3.7 V, 3.65 V, 3.6 V, 3.55 V or 3.5 V, and the lower limit is not specifically limited, but may be, for example, about 1 V, 1.5 V, 2 V, 2.5 V, 3 V, 3.1 V, 3.2 V, 3.3 V or 3.4 V. i 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 upper limit arbitrarily selected from the lower 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 and less than or equal to an upper limit arbitrarily selected from the upper limits listed above.

[0060] The polymer layer may have a lower oxidation potential than the active material layer (or the electrode active material included in the active material layer). The active material layer or the electrode active material is an active material layer or an electrode active material of a positive or negative electrode in which the polymer layer is included. The oxidation potential is a Li / Li+ reference oxidation potential unless otherwise specified. The oxidation potential of the polymer layer is measured by the method described in "4. Measurement of oxidation potential of polymer layer" in the Examples section of this specification, and the oxidation potential of the electrode active material and / or the active material layer is measured by the method described in "5. Measurement of oxidation potential of electrode active material" in the Examples section of this specification. The oxidation potential is lithium and lithium ion (Li / Li) + ) is the oxidation potential measured based on the standard.

[0061] In one example, in the electrode assembly, the oxidation potential of the polymer layer can be controlled so that △V2 in Equation 2 below is within a predetermined range.

[0062] [Formula 2]

[0063] △V2= 100 × (V a - V s ) / V a

[0064] V in Equation 2 a is the oxidation potential of the active material layer or the electrode active material included therein, and V s is the oxidation potential of the polymer layer.

[0065] The lower limit of △V2 in Equation 2 may be about 0%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, or 8.5%, and the upper limit may be about 0%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, or 4.5%. △V2 in Equation 2 is within a range that is equal to or greater than any one lower limit arbitrarily selected from the lower limits listed above; Alternatively, it may be 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 a 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.

[0066] Oxidation potential V of the above polymer layer s is not particularly limited as long as it satisfies the above relationship. The oxidation potential V of the polymer layer sThe lower limit may be about 2V, 2.1V, 2.2V, 2.3V, 2.4V, 2.5V, 2.6V, 2.7V, 2.8V, 2.9V, 3V, 3.1V, 3.2V, 3.3V, 3.4V, 3.5V, 3.6V or 3.7V, and the upper limit may be about 6V, 5.5V, 5V, 4.9V, 4.8V, 4.7V, 4.6V, 4.5V, 4.4V, 4.3V, 4.2V, 4.1V, 4.0V, 3.9V, 3.8V, 3.7V, 3.6V or 3.5V. The oxidation potential may be within a range that is less than or equal to any one of the upper limits arbitrarily selected from the upper limits listed above; within a range that is greater than or equal to any one of the lower limits arbitrarily selected from the lower 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.

[0067] 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 unit of the DC resistance is Ω·cm. 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 DC resistance is measured by the method described in “6. DC resistance measurement method” of the Examples section of the present specification.

[0068] 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 unit of the above AC impedance resistance is Ω. The above 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 above AC resistance is measured in the manner described in “7. AC Impedance Resistance” of the Examples section of this specification.

[0069] By exhibiting the above DC resistance and / or AC impedance resistance, the secondary battery to which the electrode assembly is applied can be stably operated and stored in a normal state.

[0070] The above electrode exhibits increased resistance in an abnormal state, thereby blocking the current flow of the electrode assembly, thereby ensuring stability.

[0071] The above polymer layer or the electrode or electrode assembly to which the above polymer layer is applied can exhibit a characteristic in which △R1 of the following equation 3 is at a certain level or higher.

[0072] [Formula 3]

[0073] △R1 = Max{(R n+5 / R n ) / 5}

[0074] R in Equation 3 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.

[0075] The method for measuring △R1 of Equation 3 is described in the "8. Measurement of maximum resistance change rate (DC resistance)" section of the Examples section. In the method for confirming 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.

[0076] The lower limit of △R1 in Equation 3 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.

[0077] The temperature (on-set temperature) at which △R1 within the above range is confirmed may be within a predetermined range. The above temperature range is crucial for ensuring the stable operation and stability of the secondary battery. In other words, if the above temperature is within the normal temperature range of the secondary battery, a temperature increase within that temperature range will adversely affect the performance of the secondary battery. The lower limit of the above onset 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.

[0078] 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.

[0079] The above polymer layer and the electrode to which the above polymer layer is applied can exhibit a characteristic in which △R2 of the following equation 4 is at a certain level or higher.

[0080] [Formula 4]

[0081] △R2 = Max{(R z+5 / R z ) / 5}

[0082] R in Equation 4 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.

[0083] The method of measuring △R2 of Equation 4 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 And check Rz. For example, if z is 90, R 95 / R 90 is the ratio of the AC impedance resistance at 95°C to the AC impedance resistance at 90°C.

[0084] The lower limit of △R2 in Equation 4 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 △R2 is Ω / ℃, and the range 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.

[0085] 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.

[0086] The temperature at which the above △R2 is confirmed (on-set temperature) may be within a predetermined range. 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 may be 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.

[0087] 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.

[0088] The polymer layer, the 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 5 below is within a certain range.

[0089] [Formula 5]

[0090] △R3 = 100 × (C1-C2) / C1

[0091] In Equation 5, 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 5 are the discharge capacities measured for the coin cell with the polymer layer.

[0092] The upper limit of the absolute value of △R3 in Equation 5 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.

[0093] The polymer layer, the 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 6 below is within a predetermined range.

[0094] [Formula 6]

[0095] △R4 = 100 × (C 25- C 130 ) / C 25

[0096] C in Equation 5 25 is the discharge capacity at room temperature (approximately 25℃), and C 130 is the discharge capacity after 10 minutes of storage at 130℃.

[0097] C in Equation 5 25 and C 130 is the discharge capacity measured for the coin cell to which the polymer layer is applied, and the specific method of measuring this is outlined in “11. High-temperature discharge capacity reduction rate” of the Examples section.

[0098] The lower limit of the absolute value of △R4 in Equation 6 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.

[0099] The polymer layer can exhibit excellent electrical reactivity. For example, the polymer layer can be formed so that Q in Equation 7 below falls within a predetermined range.

[0100] [Formula 7]

[0101] Q = R 3V / R 3.5V

[0102] R in Equation 7 3V is the AC impedance resistance at 25℃ and 3V external voltage conditions, and R 3.5V is the AC impedance resistance at the point where the external voltage is converted to 3.5 V under the above 25℃ and 3 V external voltage conditions and 1 second has passed. The AC impedance resistance R 3V and R 3.5V is the resistance confirmed in the coin cell to which the electrode assembly is applied, and the measurement method thereof is according to the method described in the “13. AC impedance resistance measurement at 3 V and 3.5 V” section of the Examples section of this specification.

[0103] The lower limit of the above Q value may be about 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 115, 120, 125, 130, 135 or 140, and the upper limit may be about 400, 350, 300, 250, 200, 195, It can be about 190, 185, 180, 175, 170, 165, 160, 155, 150, 145, 140, 130, 120, 110, 100, 99, 98, 97, 96, 95, 94, 93, 92, 91, 90, 89, 88, 85, 80, 70, 60, 50, 30, 20 or 10. The Q value can 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.

[0104] The fact that the Q value of the above formula 7 is greater than a certain value means that when the external voltage condition changes from 3 V to 3.5 V, a rapid decrease in resistance occurs within a short period of time, which indicates excellent electrical reactivity of the polymer layer or the conductive polymer included therein.

[0105] AC impedance resistance R of Equation 7 3.5V can be within a certain range. For example, the AC impedance resistance R 3.5VThe upper limit can be, for example, 5000, 4500, 4000, 3500, 3000, 2500, 2000, 1500, 1000, 900, 800, 700, 600, 500, 400, 350, 300 or 250, and the lower limit can be, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 150, 200, 250, 300, 500, 1000, 1500, 2000, 2500, It can be around 3000, 3500, 4000, 4500 or 5000. The above AC impedance resistance R 3.5V The unit of is Ω, and the range can be within a range that is greater than or equal to a lower limit arbitrarily selected from the lower limits listed above; within a range that is less than or equal to a upper limit arbitrarily selected from the upper limits listed above; or within a range that is greater than or equal to a lower limit arbitrarily selected from the lower limits listed above and less than or equal to a upper limit arbitrarily selected from the upper limits listed above.

[0106] The above polymer layer exhibits a precisely designed PTC (Positive Temperature coefficient) effect, and accordingly, when the polymer layer is applied to an electrode, the electrode can maintain excellent electrical characteristics at a normal temperature and exhibit a resistance increasing effect at an abnormal temperature.

[0107] For example, the polymer layer can be designed so that P in Equation 8 below is within a predetermined range.

[0108] [Formula 8]

[0109] P = R 130 / R 25

[0110] R in Equation 8 130 is the AC impedance resistance at 130℃, and R 25is the AC impedance resistance at 25℃. The AC impedance resistance R 130 and R 25 is the resistance confirmed in the coin cell to which the electrode assembly is applied, and the measurement method thereof follows the method described in the “14. AC impedance resistance measurement at room temperature (25°C) and 130°C” section of the Examples section of this specification.

[0111] The lower limit of P in Equation 3 may be about 60, 70, 80, 90 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1,000, 1,100, 1,200, 1,300, 1,400 or 1,450, and the upper limit may be, but is not particularly limited to, 10,000, 9,000, 8,000, 7,000, 6,000, 5,000, 4,000, 3,000, 2,000 1,500, It can be about 1,400, 1,300, 1,200, 1,100, 1,000, 950, 900 or 850. The P can 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.

[0112] The above polymer layer shows a large resistance difference at room temperature (approximately 25°C) and high temperature (130), which is due to the PTC effect.

[0113] The polymer layer, the current collector including the polymer layer, or the electrode including the polymer layer can exhibit a low resistance value at room temperature (about 25°C) while exhibiting the P value.

[0114] For example, the resistance R of the AC impedance of the above equation 3 25The upper limit of the AC impedance may be, for example, about 500, 450, 400, 350, 300, 250, 200, 150, 100, 90, 80, 70, 60, 50, 45, 40, 35, 30, 28, 26, 24 or 22, and the lower limit may be, for example, about 10, 15, 20, 25, 30, 35 or 40. The resistance R of the AC impedance 25 The unit of is Ω, and the range 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 and less than or equal to any upper limit arbitrarily selected from the upper limits listed above.

[0115] The electrode assembly including the above polymer layer and separator can exhibit excellent stability even against external impact.

[0116] For example, the electrode assembly may exhibit a maximum temperature below a certain level in an impact test.

[0117] The above maximum temperature is the maximum temperature confirmed in the Impact test performed according to Test Example 3 of this specification. The upper limit of the maximum temperature may be about 200°C, 150°C, or 100°C, and the lower limit may be about 20°C, 40°C, 60°C, or 80°C. The above maximum temperature 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 equal to or greater than 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.

[0118] In addition, the electrode assembly may exhibit a temperature rise rate below a certain level in the impact test. The upper limit of the temperature rise rate may be about 40, 35, 30, 25, 20, 15, 10, 5, 1, or 0.5, and the lower limit may be about 0.01, 0.05, 0.1, 0.15, or 0.2. The temperature rise rate 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 equal to or greater than 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. The unit of the temperature rise rate is 40°C / sec.

[0119] The above maximum temperature and temperature rise rate can be confirmed according to the contents of Test Example 3 of this specification.

[0120] The conductive polymer included in the above polymer layer 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 is 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, 95,000, 100,000, 105,000, 110,000, 115,000, 120,000, 125,000, 130,000, 135,000, 140,000, It may be about 145,000 or 150,000, and its upper limit may be about 1,000,000, 950,000, 900,000, 850,000, 800,000, 750,000, 700,000, 650,000, 600,000, 550,000, 500,000, 450,000, 400,000, 350,000, 300,000, 250,000, 200,000, 150,000 or 120,000. The weight average molecular weight is 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 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. The unit of the weight average molecular weight is g / mol.

[0121] The molecular weight distribution of the conductive polymer, i.e., the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), may be within a predetermined range. The lower limit of the molecular weight distribution may be about 1, 1.5, 2, 2.5, 3, 3.5, 4, or 4.5, and the upper limit may be about 8, 7.5, 7, 6.5, 6, 5.5, 5, 4.5, 4, or 3.5. The molecular weight distribution may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above; 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.

[0122] The above weight average molecular weight and molecular weight distribution can be evaluated by the method described in “2. GPC (Gel Permeation Chromatograph)” of the Examples section of this specification.

[0123] The above conductive polymer may be polythiophene.

[0124] The term polythiophene refers to a polymer containing a certain level of thiophene units.

[0125] The term thiophene unit refers to a monomer unit whose monomer is a thiophene monomer.

[0126] The term thiophene monomer refers to a monomer of the thiophene series, which contains a thiophene skeleton.

[0127] The term monomer unit refers to the form in which a monomer is polymerized and included in a polymer.

[0128] For example, the lower limit of the ratio of the mole number of the thiophene unit in the polythiophene may be about 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, 85 mol% or 90 mol% relative to the mole number of all monomer units of the polythiophene, and the upper limit may be about 100 mol%, 95 mol%, 90 mol%, 85 mol%, 80 mol%, 75 mol%, 70 mol%, 65 mol% or 60 mol% relative to the mole number of all monomer units of the polythiophene. The ratio of the thiophene unit 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.

[0129] The 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 monomer having the long-chain hydrocarbon functional group may be a thiophene monomer.

[0130] The term long-chain hydrocarbon functional group means a monovalent hydrocarbon group having a carbon number greater than or equal to a certain level or a monovalent functional group including a monovalent hydrocarbon group having a carbon number greater than or equal to the certain level.

[0131] 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.

[0132] The above carbon number may be the total number of carbons present in the long-chain hydrocarbon functional group, or the carbon number of a hydrocarbon chain having a straight-chain structure included in the functional group. That is, the monovalent hydrocarbon group present in the long-chain hydrocarbon functional group may have a straight-chain structure or a branched-chain structure, and even in the case of 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.

[0133] 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.

[0134] 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).

[0135] For example, the alkyl group, alkenyl group, alkynyl group, the alkoxy group, the alkyl group of the alkylcarbonyl group and the alkyl group of the alkylcarbonyloxy group may have a straight or branched chain structure, and 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.

[0136] 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.

[0137] These long-chain hydrocarbon functional groups are functional groups that can impart appropriate mobility to the monomer or the conductive polymer itself during the polymerization process of the conductive polymer. The monomer containing such a long-chain hydrocarbon functional group imparts appropriate mobility to the monomer mixture and also diffuses within the monomer mixture, thereby enabling polymerization to occur with excellent efficiency. In addition, the conductive polymer having a long-chain hydrocarbon functional group can enable the stable and uniform formation of a polymer layer between the current collector and the active material layer through appropriate mobility.

[0138] The long-chain hydrocarbon functional group may be appropriately oriented during the drying or annealing process applied during the formation of the polymer layer, thereby enabling the control of a PTC effect suitable for the polymer. When a certain amount of heat energy is applied to the long-chain hydrocarbon functional group, the long-chain hydrocarbon functional group vibrates due to the heat, and this vibration (thermal vibration) promotes dedoping of anions bonded to the polymer, thereby inducing an increase in resistance. The temperature at which the thermal vibration occurs can be controlled by the length and / or amount of the long-chain hydrocarbon functional group. For example, under the same temperature, the thermal vibration of a relatively long chain is greater than that of a relatively short chain, and thus, the long chain can induce a resistance-increasing effect at a relatively low temperature. Therefore, the desired PTC effect can be set by controlling the length and / or ratio of the long-chain hydrocarbon functional group.

[0139] For example, in order to appropriately implement the above effect, the molar ratio of the monomer unit (unit A) having the long-chain hydrocarbon functional group relative to the molar number of the total monomer units of the conductive polymer may be adjusted. For example, the lower limit of the molar ratio may be about 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, 85 mol%, 90 mol%, or 95 mol%, and the upper limit may be about 99 mol%, 98 mol%, 96 mol%, 95 mol%, or 90 mol%. 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, and equal to or greater than any lower limit arbitrarily selected from the lower limits listed above.

[0140] The above conductive polymer may include, as the long-chain hydrocarbon functional group, a hydrocarbon functional group having 10 or more carbon atoms (hereinafter, referred to as a first hydrocarbon functional group) and a hydrocarbon functional group having 9 or less carbon atoms (hereinafter, referred to as a second hydrocarbon functional group).

[0141] The lower limit of the carbon number 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 number 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.

[0142] The lower limit of the carbon number 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 number 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.

[0143] 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.

[0144] 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.

[0145] The carbon number of a long-chain hydrocarbon functional group is related to the vibration characteristics due to applied heat energy, and as the carbon number changes, these vibration characteristics also change, and the vibration characteristics are also linked to the PTC characteristics of the conductive polymer. In the conductive polymer, the first hydrocarbon functional group mainly plays a role in controlling the temperature at which the PTC effect is expressed, i.e., the temperature at which an increase in resistance occurs, and the second hydrocarbon functional group plays a role in suppressing an increase in resistance at relatively low temperatures.

[0146] In the conductive polymer, the ratio of the total mole number of monomer units having the first hydrocarbon functional group and the second hydrocarbon functional group to the mole number of all monomer units of the conductive polymer can be adjusted within the range of the ratio of the unit A described above.

[0147] The lower limit of the ratio (M2 / M1) of the mole number (M2) of the second hydrocarbon functional group or the monomer unit having the functional group in the conductive polymer to the mole number (M1) of the first hydrocarbon functional group or the monomer unit having the functional group may be about 0.01, 0.05, 0.1, 0.5, 1, 1.5 or 2, 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 have a range between being less than or equal to an upper limit arbitrarily selected from the upper limits listed above, being greater than or equal to an lower limit arbitrarily selected from the lower limits listed above, or being less than or equal to an upper limit arbitrarily selected from the upper limits listed above and being greater than or equal to an lower limit arbitrarily selected from the lower limits listed above.

[0148] Under such a ratio, the conductive polymer or the polymer layer exhibits an appropriate PTC (Positive Temperature Coefficient) effect, exhibits stable electrical characteristics at a normal temperature, and the surface characteristics of the polymer layer are controlled to ensure excellent adhesion to the electrode or current collector for the electrode.

[0149] The conductive polymer may include a polar functional group or a monomer unit having the polar functional group (hereinafter referred to as unit B) together with the long-chain hydrocarbon functional group or unit A. The monomer having the polar functional group may be a thiophene monomer.

[0150] 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, or a functional group represented by the following chemical formula 1. In one example, the polar functional group may be a functional group represented by the following chemical formula 1.

[0151] [Chemical Formula 1]

[0152]

[0153] 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 n is an arbitrary number.

[0154] 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.

[0155] 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.

[0156] The term alkylene group refers to a divalent functional group formed by the removal of hydrogen atoms from two different carbon atoms in an alkane, and the term alkylidene group refers to a divalent functional group formed by the removal of two hydrogen atoms from one carbon atom in an alkane.

[0157] 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.

[0158] 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.

[0159] In chemical formula 1, the lower limit of n may be 1, 2, 3, or 4, and the upper limit may be 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.

[0160] By applying the above polar functional group, a polymer layer can be bonded to another layer with appropriate bonding strength, and a layer of such conductive polymer can be uniformly formed to efficiently achieve the desired protective function. In addition, the above polar functional group can also play a role in suppressing the PTC effect from appearing at relatively low temperatures.

[0161] 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.

[0162] For example, the number of moles (M) of the long-chain hydrocarbon functional groups in the conductive polymer L ) and the number of moles of the polar functional group (M P ) ratio (M L / M P ) may be about 1, 5, 8, 10, 15, 16, 17, 18 or 19, and its upper limit may be about 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 or 10. 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.

[0163] The number of moles of the above unit A in the conductive polymer (M A ) of the above unit B moles (M B ) for the ratio (M A / M B ) may be about 1, 5, 8, 10, 15, 16, 17, 18 or 19, and its upper limit may be about 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 or 10. The above ratio M A / M BIt 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.

[0164] The lower limit of the ratio of the total mole number of the units A and B to the total mole number of all monomer units of the conductive polymer may be about 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, 85 mol%, or 90 mol%, and the upper limit may be about 100 mol%, 95 mol%, 90 mol%, 85 mol%, 80 mol%, 75 mol%, 70 mol%, 65 mol%, or 60 mol% relative to the mole number of all monomer units of the polythiophene. 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 and equal to or greater than any lower limit arbitrarily selected from the lower limits listed above.

[0165] The specific structure of the monomer included in the conductive polymer is not particularly limited as long as it is a thiophene monomer having the long-chain hydrocarbon functional group and / or polar functional group described above.

[0166] For example, the conductive polymer may include a unit of the following chemical formula 2 as the thiophene unit.

[0167] [Chemical Formula 2]

[0168]

[0169] 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.

[0170] [Chemical Formula 3]

[0171]

[0172] 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.

[0173] 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.

[0174] 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.

[0175] In chemical formula 3, the meanings and specific examples of single bonds, alkylene groups, and alkylidene groups are the same as in chemical formula 1.

[0176] The technical significance and specific examples of the long-chain hydrocarbon functional group and polar functional group in chemical formulas 2 and 3 are as described above.

[0177] The lower limit of the ratio of the number of moles of the unit of the above chemical formula 2 based on the total monomer units of the conductive polymer may be about 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, 85 mol%, or 90 mol%, and the upper limit may be about 100 mol%, 95 mol%, 90 mol%, 85 mol%, 80 mol%, 75 mol%, 70 mol%, 65 mol%, or 60 mol% based on the total number of moles of the monomer units of the polythiophene. The ratio is 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 less than or equal to any upper limit arbitrarily selected from the upper 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 at the same time less than or equal to any upper limit arbitrarily selected from the upper limits listed above.

[0178] In one example, the conductive polymer may include a monomer unit represented by the following chemical formula 4. The monomer unit of chemical formula 4 may be an example of a monomer unit having the first hydrocarbon functional group.

[0179] [Chemical Formula 4]

[0180]

[0181] 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.

[0182] In another example, R6 and R7 can be linked to each other to form a divalent functional group of the following chemical formula 5.

[0183] [Chemical Formula 5]

[0184]

[0185] 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.

[0186] 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.

[0187] The above conductive polymer may also include a monomer unit represented by the following chemical formula 6.

[0188] The monomer unit of the above chemical formula 6 may be an example of a monomer unit having the second hydrocarbon functional group.

[0189] [Chemical Formula 6]

[0190]

[0191] 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.

[0192] 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.

[0193] [Chemical Formula 7]

[0194]

[0195] 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 12and R 13 At least one of the above is a second hydrocarbon functional group.

[0196] 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.

[0197] The conductive polymer may also include a monomer unit represented by the following chemical formula 8. The monomer unit of chemical formula 8 may be an example of a monomer unit having the polar functional group.

[0198] [Chemical Formula 8]

[0199]

[0200] R in chemical formula 8 14 and R 15 Each of R can independently be hydrogen or the polar functional group. 14 and R 15 At least one of the above polar functional groups.

[0201] 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.

[0202] [Chemical Formula 9]

[0203]

[0204] 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 the polar functional group, R 16 and R 17 At least one of the above polar functional groups.

[0205] 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.

[0206] When the conductive polymer simultaneously includes the monomer unit of the above chemical formula 4 and the monomer unit of the above chemical formula 6, the ratio of the total mole number of the monomer unit of the above chemical formula 4 and the monomer unit of the above chemical formula 6 to the mole number of the total monomer units included in the conductive polymer can be adjusted within the same range as the mole ratio of the unit A described above.

[0207] The molar ratio of the monomer unit of the above chemical formula 4 and the monomer unit of the above chemical formula 6 can be adjusted within the same range as the molar ratio M2 / M1 described above. In this case, the molar number M1 can be the molar number of the monomer unit of the above chemical formula 4, and the molar number M2 can be the molar number of the monomer unit of the above chemical formula 6.

[0208] When the conductive polymer contains monomer units of the above chemical formula 8, the units are present in the above-mentioned molar ratio M A / M B It can be included in the range within the range of . At this time, the mole number of the monomer unit of the chemical formula 8 is mole number M B becomes. Also, the confiscation M above A 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.

[0209] When the monomer units of the chemical formulae 4, 6 and 8 are present in the conductive polymer, the lower limit of the ratio of the total mole number of the monomer units of the chemical formulae 4, 6 and 8 to the total mole number of all monomer units in the conductive polymer may be about 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, 85 mol% or 90 mol%, and the upper limit may be about 100 mol%, 95 mol%, 90 mol%, 85 mol%, 80 mol%, 75 mol%, 70 mol%, 65 mol% or 60 mol% relative to the mole number of all monomer units of the polythiophene. 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 less than or equal to any upper limit arbitrarily selected from the upper 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 at the same time less than or equal to any upper limit arbitrarily selected from the upper limits listed above.

[0210] The conductive polymer may additionally include other monomer units as long as they contain the aforementioned units in the aforementioned proportions. The polymer layer may include the aforementioned conductive polymer and thus exhibit the aforementioned properties.

[0211] The conductive polymer may additionally contain other monomer units as long as they contain the aforementioned units in the above proportions.

[0212] The above polymer layer may include a conductive material together with the above conductive polymer.

[0213] 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, carbon nanotubes, and metal particles.

[0214] As the above-mentioned conductive material, an appropriate type may be selected and used from the types described above, and the shape 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.

[0215] The size of the above-mentioned challenging material can also be appropriately adjusted as needed. For example, the lower limit of the size of the conductive 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 or 150 nm, 100 nm, 90 nm, 80 nm, 70 nm or 65 nm. The size may be greater than or equal to any lower limit selected from the lower limits listed above, less than or less than any upper limit selected from the upper limits listed above, or greater than or equal to any lower limit selected from the lower limits listed above and less than or less than any upper limit selected from the upper limits listed above. The above size may be the average diameter (so-called D50 particle size) of the conductive material in the form of particles, the thickness, long side or cross-section of the conductive material in the form of plates, or the diameter or length of the cross-section of the conductive material in the form of fibers.

[0216] When the above-mentioned conductive material is in the form of fiber, the lower limit of the aspect ratio (length / cross-sectional diameter) may be about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60 or 65, and the upper limit may be about 200, 195, 190, 185, 180, 175, 170, 165, 160, 155, 150, 145, 140, 135, 130, 125, 120, 115, 110, 105, 100, 95, 90, 85, 80, 75 or 70. The above aspect ratio 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.

[0217] If necessary, the conductive material may be surface-treated to take dispersibility, etc. into consideration.

[0218] In this case, a conductive core and a surface layer present on the surface of the core may be included. In this case, one or more types of conductive materials selected from carbon particles, carbon fibers, graphene, graphite, carbon black, carbon nanotubes, and metal particles become the conductive core.

[0219] As a surface treatment agent, a surface treatment agent having appropriate compatibility with the conductive polymer can be used. For example, the conductive material may be surface-treated with a polyphenol-based compound as a surface treatment agent. In this case, the surface layer may include the polyphenol-based compound. The polyphenol-based compound refers to a compound having a structure including 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.

[0220] 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.

[0221] When the above conductive material is used, the ratio of the conductive material within the polymer layer can be adjusted according to the purpose (e.g., the desired oxidation potential). For example, the lower limit of the weight ratio of the conductive material to 100 parts by weight of the conductive polymer in the polymer layer may be about 1 part by weight, 5 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 42 parts by weight, 44 parts by weight, 46 parts by weight, 48 parts by weight, 50 parts by weight, 52 parts by weight, 54 parts by weight, 56 parts by weight, 58 parts by weight, 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, 80 parts by weight, 85 parts by weight, 90 parts by weight, 95 parts by weight or 100 parts by weight, and the upper limit may be about, for example, 1,000 parts by weight, 950 parts by weight, 900 parts by weight, 850 parts by weight, 800 parts by weight, 750 parts by weight, 700 parts by weight, 650 parts by weight, 600 parts by weight, 550 parts by weight, 500 parts by weight, 450 parts by weight, 400 parts by weight, 350 parts by weight, 300 parts by weight, 250 parts by weight, 200 parts by weight, 150 parts by weight, 145 parts by weight, 140 parts by weight, 135 parts by weight, 130 parts by weight, 125 parts by weight, 120 parts by weight, 115 parts by weight, 110 parts by weight, 105 parts by weight, 100 parts by weight, 95 parts by weight, 90 parts by weight, 85 parts by weight, 80 parts by weight, 75 parts by weight, 70 parts by weight, 65 parts by weight, 60 parts by weight, 55 parts by weight, 50 parts by weight, 45 parts by weight, 40 parts by weight, 35 parts by weight, 30 parts by weight or 25 parts by weight The content 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.

[0222] Under such a ratio, the conductive material can appropriately interact with the conductive polymer to effectively form a polymer layer of the desired shape.

[0223] For example, the conductive material can have the effect of adjusting the oxidation potential of the polymer layer and improving the electrical reactivity of the polymer layer.

[0224] The polymer layer may also include any additional components, as long as it includes the conductive polymer and the conductive material.

[0225] The thickness of the above polymer layer can be appropriately controlled depending on the purpose. For example, the lower limit of the thickness of the polymer layer 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 or 1000 nm, and the upper limit may be about 2 μm, 1.5 μm, 1 μm, 950 nm, 900 nm, 850 nm, 800 nm, 750 nm, 700 nm, 650 nm, 600 nm, 550 nm, 500 nm, 450 nm, 400 nm, 350 nm or It may be about 300 nm. The thickness 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.

[0226] The above polymer layer can be manufactured by the method described below.

[0227] For example, the method for manufacturing the polymer layer may include, for example, a first step of forming a precursor including a conductive polymer and a conductive material and a step of heat-treating the precursor.

[0228] The conductive polymer and conductive material used to form the precursor may be any of the conductive polymers and conductive materials described above. The conductive polymers and materials may be manufactured by known methods, or may be commercially available products. For example, methods for manufacturing polythiophene include methods utilizing oxidative polymerization and radical reactions, and these methods can also be applied to the process of forming the conductive polymer. Furthermore, commercially available conductive materials may be used, and their surface treatment may be performed by known methods.

[0229] The above precursor means, for example, a layer including the conductive polymer and conductive particles, which ultimately becomes the polymer layer.

[0230] Such precursors can be formed by a known method, for example, by coating a polymer solution in which the conductive polymer or the like is dispersed in an appropriate solvent.

[0231] As the solvent, an appropriate solvent capable of dispersing the conductive polymer and conductive material may be selected, and examples thereof include, but are not limited to, ether solvents such as diethyl ether, tetrahydrofuran, dioxane, trioxane, dimethoxyethane, or toluene; aromatic hydrocarbon solvents such as ethyl benzene or alicyclic hydrocarbon solvents such as cyclohexane; tertiary amine solvents such as tetramethylethylenediamine (TMEDA) or hexamethylphosphorictriamide (HMPA), or mixed solvents containing two or more of the above.

[0232] The above polymer solution is used to form a precursor. This process can typically be performed by coating the polymer solution onto an appropriate process substrate. There are no specific restrictions on the coating method.

[0233] The above manufacturing method further includes a step of heat-treating the precursor of the polymer layer. By adjusting the conditions during this process, the orientation state of the conductive polymer (e.g., the orientation state of the long-chain hydrocarbon functional group and / or the polar functional group) and / or the dispersion state of the conductive material can be adjusted or stabilized, thereby forming a polymer layer that satisfies the desired PTC effect, oxidation potential characteristics, and other characteristics.

[0234] The heat treatment step may be performed in two stages. For example, the heat treatment step may include a second stage of first heat treating the precursor of the first stage at a temperature range T1; and a third stage of second heat treating the precursor at a temperature range T2 following the second stage.

[0235] The conditions of the second and third steps can be adjusted to achieve orientation or alignment of the conductive polymer and dispersion state of the conductive material.

[0236] 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.

[0237] 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 (T1 / T2) 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.

[0238] 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.

[0239] 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 above ratio M2 / M1 may be about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 50, 70, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260 or 270, and the upper limit may be about 1,000, 950, 900, 850, 800, 750, 700, 650, 600, 550, 500, 450, It can be about 400, 350, 300, 290, 280, 270, 250, 200, 150, 100, 90, 80, 70, 60, 50, 40, 30 or 20. The ratio M2 / M1 can 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.

[0240] The lower limit of the above 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 hours. It can be about 15 hours, 10 hours, 9 hours, 8 hours, 7 hours, 6 hours, 5 hours, 4 hours, 3 hours, 2 hours, 1.5 hours or 1 hour. The secondary heat treatment time M2 can 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.

[0241] The polymer layer can be formed through the above process.

[0242] Through this heat treatment process, the orientation state of the conductive polymer (e.g., the orientation state of the long-chain hydrocarbon functional group and / or the polar functional group) and / or the dispersion state of the conductive material can be adjusted or stabilized, thereby forming a polymer layer that satisfies the desired PTC effect, oxidation potential characteristics, and other characteristics.

[0243] As the current collectors of the positive and negative electrodes, those commonly used as current collectors for positive or negative electrodes can be used without any special restrictions.

[0244] As for the current collector, as long as it is conductive and does not cause chemical changes in an application device such as a secondary battery, its type, size, shape, etc. are not particularly limited. Examples of materials that can be used as the current collector include copper, aluminum, stainless steel, nickel, titanium, or calcined carbon, or materials whose surfaces are surface-treated with carbon, nickel, titanium, or silver, etc. of copper, aluminum, or stainless steel, etc. 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.

[0245] The entire body has a thickness typically within the range of 3 μm to 500 μm, but is not limited thereto.

[0246] The active material layer used in forming the electrode can also be a layer commonly applied. Typically, the active material layer includes an electrode active material. There are no specific limitations on the specific type of the electrode active material, and any material that typically forms a positive or negative electrode can be used.

[0247] 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 c2Ni-site type lithium nickel oxide represented by O2 (wherein, M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, 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.

[0248] 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.

[0249] 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.

[0250] 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.

[0251] The active material layer may additionally include a binder. The binder serves to improve adhesion between active materials and adhesion between the active material layer and the current collector. Examples of the above 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.

[0252] The above binder may be included in the active material layer in an amount of, in one example, 0.1 to 10 parts by weight or 0.5 to 5 parts by weight relative to 100 parts by weight of the electrode active material, but is not limited thereto.

[0253] 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.

[0254] 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.

[0255] In addition to the components described above, the active material layer may additionally include any known components required.

[0256] There are no specific limitations on the method for manufacturing an electrode by forming the active material layer on a polymer layer. Typically, the active material layer is formed by coating a slurry containing the electrode active material, a binder, and a conductive agent on a current collector (polymer layer), drying it, and then rolling it. This known method can be equally applied to the present application.

[0257] The electrode assembly can be formed using the positive and negative electrodes formed in the above manner and the separator described above.

[0258] The present specification also discloses an electrochemical device, such as a secondary battery, comprising the electrode assembly. As long as the battery chemical device uses the electrode assembly, other components or manufacturing methods included therein are not particularly limited, and known methods may be applied.

[0259] The present specification discloses an electrode assembly and a secondary battery. The present specification discloses an electrode assembly comprising an electrode that exhibits low resistance and excellent electrical characteristics in a normal state of the secondary battery and can quickly convert into an insulator to ensure stability in an abnormal state, and a separator, called a safety-reinforcing separator (SRS). The present specification also discloses a secondary battery comprising the electrode assembly.

[0260] Figure 1 is a side view of an exemplary electrode assembly.

[0261] Figure 2 is a side view of an exemplary membrane.

[0262] Figure 3 is a side view of an exemplary electrode.

[0263] Figure 4 shows the NMR analysis results of the compound manufactured in the manufacturing example.

[0264] Figure 5 is an SEM image of the electrode of the embodiment.

[0265] Figure 6 shows the analysis results for Coin Haspel of Test Example 1.

[0266] Figure 7 is a charge / discharge profile of the cycle test of Test Example 1.

[0267] Figure 8 shows the results of energy density retention (140 cycles) of Test Example 1.

[0268] Figure 9 shows the rate test results of the 3-Ah pouch cell of Test Example 1.

[0269] Figure 10 shows the results of a cycle test of the 3-Ah pouch cell of Test Example 1.

[0270] Figure 11 is a drawing for explaining a method for performing an impact test.

[0271] Figure 12 is a diagram showing the maximum temperature and temperature rise rate of the impact test.

[0272] The electrode assembly and the like are specifically described through the following examples and comparative examples, but the scope of the electrode assembly and the like is not limited by the following examples.

[0273]

[0274] 1. NMR analysis

[0275] 1 H-NMR analysis was performed at room temperature (approximately 25°C) using an NMR spectrometer (including a Bruker UltraShield spectrometer (300 MHz)) equipped with a triple resonance 5 mm probe. Samples were diluted in NMR measuring solvent (CDCl3) to a concentration of approximately 10 mg / ml, and chemical shifts were expressed in ppm.

[0276]

[0277] 2. GPC (Gel Permeation Chromatograph)

[0278] Molecular weight characteristics were measured using gel permeation chromatography (GPC). Samples were placed in 5 mL vials and diluted with chloroform to a concentration of approximately 1 mg / mL. Calibration standard samples and analysis samples were filtered through a syringe filter (pore size: 0.45 μm) and then measured. The analysis program used Waters' Empower 3, and the weight-average molecular weight (Mw) and number-average molecular weight (Mn) were calculated by comparing the elution time of the sample with the calibration curve. The molecular weight distribution (PDI) is equivalent to the value Mw / Mn, which is the weight-average molecular weight Mw divided by the number-average molecular weight Mn. The GPC measurement conditions are as follows.

[0279] <GPC 측정 조건>

[0280] Device: Waters 2414

[0281] Column: Using 3 Styragel from Waters

[0282] Solvent: THF (Tetrahydrofuran)

[0283] Column temperature: 35℃

[0284] Sample concentration: 1 mg / mL, 1 μL injection

[0285] Standard samples: polystyrene (Mp: 3900000, 723000, 316500, 52200, 31400, 7200, 3940, 485)

[0286]

[0287] 3. Thickness measurement

[0288] After exposing the cross-section of the thickness measurement target using an ion milling device (Hitachi, IM5000), an SEM (Scanning Electron Microscope) (JEOL, JSM-7200F) image of the cross-section was taken, and the thickness was obtained from the image. The exposure of the cross-section was performed under the conditions of the ion milling device (Hitachi, IM5000) in cross-section milling mode, speed (reciprocation / min) 3, acceleration voltage 6 kD, discharge voltage 15 kV, and current 150 μA, and the time was set to 4 hours. The SEM (Scanning Electron Microscope) (JEOL, JSM-7200F) image was taken under the condition of a voltage of 5 kV, with the magnification adjusted within the range of 500 to 20,000 times.

[0289]

[0290] 4. Measurement of polymer layer oxidation potential

[0291] A polymer layer is formed on aluminum foil (Al Foil) having a thickness of about 15 μm. The polymer layer is formed in the manner described in each example or comparative example, and is formed to have a thickness of about 10 μm. A separator and a lithium film (thickness: about 100 μm) are laminated on the polymer layer to manufacture a laminate (Al Foil / polymer layer / separator / lithium film). The laminate is stamped into a circle with a diameter of about 1.4 cm. A coin cell is manufactured using the stamped laminate and the electrolyte. The coin cell is manufactured using a CR2032 coin cell kit from Wellcos. The separator is the WL20C model from W-Scope Korea. The electrolyte is 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)). For the above coin cell, the oxidation potential is measured at 25°C using a potentiostat (Princeton Applied Research, PARASTAT-MC). Cyclic voltammetry (CV) analysis is performed at a scan rate of 0.17 to 0.5 mV / sec in the range of 1.5 V to 5.5 V, and the oxidation potential (Li / Li) is determined from the analysis. + Check the standard).

[0292]

[0293] 5. Measurement of oxidation potential of electrode active material

[0294] An electrode active material (A), a conductive material (B) (ECP (Ketjen Black) 0.5%, SFG (Trimrex graphite) 0.4%, DB (Denka Black) 0.4%), PVDF (C) (poly(vinylidene fluoride)), and NMP (D) (N-Methyl-2-pyrrolidone) are mixed in a weight ratio of 75:1:1:23 (A:B:C:D) to prepare a slurry. The slurry is applied onto a current collector with a doctor blade, dried at room temperature (approximately 25°C), maintained in a drying oven at 130°C for about 30 minutes, and rolled to form an active material layer with a thickness of about 53 μm, thereby manufacturing an electrode. The rolling is performed so that the porosity of the active material layer is 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. The current collector uses aluminum foil (Al foil) having a thickness of approximately 15 μm.

[0295] A separator and a lithium film (thickness: approximately 100 μm) are laminated on the active material layer of the electrode to manufacture a laminate (electrode / separator / lithium film), and the laminate is stamped into a circle with a diameter of approximately 1.4 cm. A coin cell is manufactured using the stamped laminate and the electrolyte. The coin cell is manufactured using a CR2032 coin cell kit from Wellcos. The separator and electrolyte are the same as those used in the above "4. Measurement of polymer layer oxidation potential."

[0296] For the above coin cell, the oxidation potential is measured at 25°C using a potentiostat (Princeton Applied Research, PARASTAT-MC).

[0297] Cyclic voltammetry (CV) analysis was performed 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, and the oxidation potential (Li / Li) was determined from the analysis.+ Check the standard).

[0298]

[0299] 6. DC resistance measurement method

[0300] DC resistance was evaluated using the coin cell used in "4. Measurement of Polymer Layer Oxidation Potential." 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).

[0301]

[0302] 7. AC impedance resistance

[0303] The AC impedance resistance was evaluated by EIS (Electrochemical Impedance Spectronization) using the coin cell used in "4. Measurement of Polymer Layer Oxidation Potential." 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 using the EIS measurement method from 50,000 Hz to 0.1 Hz, and the AC impedance resistance obtained in the high frequency region was measured. A potentiostat (Princeton Applied Research, PARASTAT-MC) was used as the EIS measurement device.

[0304]

[0305] 8. Measurement of maximum resistance change rate (DC resistance)

[0306] The maximum resistance change rate △R1 is determined according to Equation 3 below.

[0307] <Formula 3>

[0308] △R1 = Max{(R n+5 / R n ) / 5}

[0309] R in Equation 3 n is the DC resistance at any temperature (n℃) within the range of 25℃ to 135℃, and Rn+5 is the DC resistance at a temperature 5℃ higher than the above temperature ((n+5)℃).

[0310] The above △R1 is measured in the following manner.

[0311] Place the coin cell for DC resistance measurement (same as used in "6. DC resistance measurement method") in the center of the convection oven (Jeotech, OF3-05W). Set the conditions of the convection oven to an initial temperature of 25℃, a final temperature of 135℃, and a heating rate of 5℃ / 1 minute. Connect the coin cell to a multimeter for resistance measurement (Fluke's digital multi-tester (FLUKE-87-5)) outside the convection oven. Measure the DC resistance at each temperature while the temperature increases as set (increase the measurement temperature by 5℃ in the order of 25℃, 30℃, 35℃, and 40℃ and measure up to 135℃). R in Equation 3 for each measurement temperature n and R n+5 Measure each, R n+5 / R n (R 30 / R 25 , R 35 / R 30 ~ R 135 / R 130 ) are calculated respectively and then divided by 5 again. In the temperature range of 25℃ to 135℃, the above (R n+5 / R n ) / 5, and then the maximum value among them is set as △R1. The above (R n+5 / R n ) / 5 is the temperature n℃ at which the maximum value is shown, which is called the on-set temperature.

[0312]

[0313] 9. Measurement of maximum resistance change rate (AC impedance)

[0314] The maximum resistance change rate △R2 is determined according to Equation 4 below.

[0315] <Formula 4>

[0316] △R2 = Max{(R z+5 / R z ) / 5}

[0317] R in Equation 4 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+5)℃).

[0318] The above △R2 is measured in the following manner.

[0319] A coin cell for AC impedance resistance measurement (same as used in "7. AC Impedance Resistance") is placed in the center of a convection oven (Jeotech, OF3-05W). The convection oven is set to have an initial temperature of 25℃, a final temperature of 135℃, and a heating rate of 5℃ / 1 min. Connect the coin cell to a potentiostat (Princeton Applied Research, PARASTAT-MC) outside the oven. Measure the AC impedance resistance at each temperature while the temperature increases as set (increase the measurement temperature by 5℃ in the order of 25℃, 30℃, 35℃, and 40℃ and measure up to 135℃). R in Equation 4 for each measurement temperature z and R z+5 Measure each, R z+5 / R z (R 30 / R 25 , R 35 / R 30 ~ R 135 / R 130 ) is calculated and divided by 5 again. In the temperature range of 25℃ to 135℃, the above (R z+5 / R z ) / 5 respectively, and then the maximum value among them is calculated as △R2. The above (R z+5 / R z) / 5 shows the maximum value, the temperature z℃ is defined as the on-set temperature. The 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.

[0320]

[0321] 10. Charge / Discharge Test

[0322] Charge and discharge tests were performed on coin cells manufactured using a coin cell kit (Wellcos) of CR2032 standard. The electrode manufactured in the examples or comparative examples was used as the positive electrode, and a lithium film (thickness: approximately 100 μm) was used as the negative electrode. The electrolyte and separator were the same as those used in the above "4. Measurement of polymer layer oxidation potential." Charge and discharge tests were performed using the coin cell, and the tests were 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.

[0323]

[0324] 11. High temperature discharge capacity reduction rate

[0325] For the same coin cell as in "10. Charge / Discharge Test", one charge / discharge was performed at 25℃, and the capacity at 0.2C was measured as the room temperature discharge capacity (C25). One charge / discharge was performed by charging at a rate of 0.2C in the CC (Constant Current) / CV (Constant Voltage) method under the conditions of a charge end voltage of 4.5 V and a charge end current of 1 mA, and discharging at a rate of 0.2C in the CC (Constant Current) method under the conditions of a discharge end voltage of 3.0 V.

[0326] After maintaining the coin cell at 130°C for approximately 10 minutes, the high-temperature discharge capacity (C130) was obtained. For the coin cell maintained at the high temperature, the following charge / discharge (1 cycle) was repeated 30 times (30 cycles), and the discharge capacity was applied as the high-temperature discharge capacity (C130). The 30 charge / discharge cycles were performed at 45°C.

[0327] Charge / Discharge (1 Cycle): Charge at a rate of 0.5C using the CC (Constant Current) / CV (Constant Voltage) method under the conditions of a charge end voltage of 4.5V and a charge end current of 1mA, then discharge at a rate of 2C using the CC (Constant Current) method under the conditions of a discharge end voltage of 3.0V.

[0328]

[0329] 12. Oxidation potential V i and V f Measurement of

[0330] Oxidation potential V i and V fis measured in the following manner. A polymer layer is formed on aluminum foil (Al Foil) (thickness: approximately 15 μm). The formation method and thickness of the polymer layer are applied in the same manner as in each embodiment or comparative example. A separator and a lithium film (thickness: approximately 100 μm) are laminated on the polymer layer to manufacture a laminate in which Al foil / polymer layer / separator / lithium film are laminated. The laminate is punched into a circle with a diameter of approximately 1.4 cm. A coin cell is manufactured using the laminate and the electrolyte punched into a circle. The coin cell is manufactured using a CR2032 coin cell kit from Wellcos. When manufacturing the coin cell, LG Energy Solution's SRS (safety-reinforcing separator) is used as the separator. The above SRS is a membrane having an inorganic particle layer including PVDF-HFP (Poly(vinylidene fluoride-co-hexafluoropropylene) and Al2O3) formed on a polymer membrane (polyethylene membrane) (pore size of about 45%), and the weight ratio of PVDF-HFP and Al2O3 (PVdF-HFP:Al2O3) is about 1:4. As an electrolyte, the same one used in the above "4. Measurement of polymer layer oxidation potential" is used. For the coin cell, the oxidation potential is measured using a potentiostat (Princeton Applied Research, PARASTAT-MC) at 25°C. CV (Cyclic Voltammetry) is performed 10 times at a scan rate of 0.83 mV / sec in the range of 3 V to 4.5 V. The oxidation potential confirmed after performing the CV once is V i , and the oxidation potential confirmed by performing 10 times is V f It is done as follows.

[0331]

[0332] 13. AC impedance resistance measurement at 3 V and 3.5 V

[0333] Sample production

[0334] A polymer layer was formed on aluminum foil (Al Foil) with a thickness of 15 μm. The method of forming the polymer layer, the thickness, etc., are the same as those described in each example or comparative example. A separator and a lithium film were laminated on the polymer layer to manufacture a laminate in which Al Foil / polymer layer / separator / lithium film were laminated, and the laminate was punched into a circle with a diameter of about 1.4 cm. A coin cell was manufactured using the punched laminate and the electrolyte (Wellcos CR2032 coin cell kit was used), and the impedance was measured using this coin cell. The SRS described above was used as the separator, a lithium film with a thickness of about 300 μm was used, and the electrolyte was the same as that used in the above "4. Measurement of polymer layer oxidation potential".

[0335]

[0336] External voltage 3V condition

[0337] The AC impedance resistance of the above coin cell was measured using the EIS (Electrochemical Impedance Spectronization) method. A voltage of 3 V was applied to the coin cell at room temperature (25°C) for 10 minutes, and the resistance R obtained in the high frequency region of the Nyquist plot obtained by the EIS measurement method in the range of 50,000 Hz to 0.1 Hz 3V was measured. A potentiostat (Princeton Applied Research, PARASTAT-MC) was used as the EIS measuring device.

[0338]

[0339] External voltage 3.5V condition

[0340] Resistance R 3V The external voltage applied to the coin cell is converted to 3.5 V, and after 1 second, the AC impedance resistance R is measured in the same way. 3.5V was measured.

[0341]

[0342] 14. AC impedance resistance measurement at room temperature (25℃) and 130℃

[0343] The AC impedance resistance was measured by the EIS (Electrochemical Impedance Spectronization) method for the coin cell (same as used in "13. AC impedance resistance measurement at 3 V and 3.5 V"). Specifically, the resistance obtained in the high frequency region from the Nyquist plot obtained by the EIS measurement method in the range of 50,000 Hz to 0.1 Hz was measured. A potentiostat (manufacturer: Princeton Applied Research, product name: PARASTAT-MC) was used as the EIS measurement device. After applying a voltage of 4.5 V to the coin cell at room temperature (25°C) for 10 minutes, the AC impedance resistance R was measured after about 1 minute when the external voltage was set to 0 V (open circuit voltage). 25 was measured.

[0344] Separately, the coin cell was placed in the center of a convection oven (Jeotech, OF3-05W), and the oven was set to a final temperature of 130°C. The coin cell was connected to a potentiostat (Princeton Applied Research, PARASTAT-MC) outside the oven to enable EIS resistance measurement. The external voltage was maintained at 0 V (open circuit voltage). In this state, the AC impedance resistance R of the polymer layer at 130°C 130 was evaluated.

[0345]

[0346] 15. Average particle size

[0347] The average particle size (D50 particle size) of the challenge particles (samples) was measured using a MASTERSIZER3000 device from Marvern in accordance with the ISO-13320 standard. Toluene was used as the solvent during the measurement. When the sample 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 size. Through the above analysis, the measurement results were converted into the particle size of a sphere having the same volume as the dispersed sample, and a volume-based cumulative graph of the particle size distribution was obtained, and the particle diameter at 50% of the cumulative point of the graph (median particle size) was designated as the average particle size (D50 particle size).

[0348]

[0349] Manufacturing Example 1. Polydopamine-coated conductive particles

[0350] As a challenge particle, Carbon Black particle (IMERYS, C·NERGY TM SUPER 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.

[0351]

[0352] Manufacturing Example 2. Synthesis of monomer (A)

[0353] The monomer of the following chemical formula A was synthesized in the following manner.

[0354] [Chemical Formula A]

[0355]

[0356] 1.372 g (12.02 mmol, 1 eq) of 3-methoxythiophene and 3 g (16.83 mmol, 1.4 eq) of triethylene glycol monomethyl ether were dissolved in 100 ml of toluene and mixed with 230 mg of p-toluenesulfonic acid (p-TsOH). The mixture was refluxed at 120°C and the methanol produced by the transetherification was removed with a 4A type molecular sieve packed in a soxhlet extractor. The reaction mixture was refluxed for 24 h, 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 target compound (monomer (A)) are shown in Figure 4.

[0357]

[0358] Manufacturing Example 3. Synthesis of polythiophene (A)

[0359] To a solution of 3.20 g (19.71 mmol, 3 eq) of iron (III) chloride dissolved in 150 ml of methylene chloride, 0.787 g (3.12 mmol, 0.475 eq) of 3-dodecylthiophene, 0.525 g (3.12 mmol, 0.475 eq) of 3-hexylthiophene, and 0.083 g (0.3285 mmol, 0.05 eq) of the monomer (A) of Preparation Example 2 were added, and polymerization was performed at 25°C for 24 hours to prepare polythiophene (A). The polymerization solution was placed in an osmotic membrane with a molecular weight cut-off (MWCO) of 5000 and immersed in 200 ml of acetonitrile to remove unreacted iron (III) chloride, monomers, and low-molecular-weight oligomers. The residue precipitated inside the osmotic membrane was washed with methanol and dried at 60°C for 12 hours to produce polythiophene (A). The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polythiophene (A) were 136,000 g / mol and 40,000 g / mol, respectively.

[0360]

[0361] Manufacturing Example 4. Synthesis of polythiophene (B)

[0362] 3-dodecylthiophene 1 g (3.94 mmol, 0.6 eq), 3-hexylthiophene 0.33 g (1.97 mmol, 0.3 eq) and monomer (A) of Preparation Example 2 0.16 g (0.66 mmol, 0.1 eq) were added to a solution of 3.20 g (19.71 mmol, 3 eq) of iron (III) chloride dissolved in 150 ml of methylene chloride, and polymerized at 30°C for 24 hours to produce polythiophene (A). The polymerization solution was placed in an osmotic membrane with a molecular weight cut-off (MWCO) of 5000 and immersed in 200 ml of acetonitrile to remove unreacted iron (III) chloride, monomers, and low-molecular-weight oligomers. The residue precipitated inside the osmotic membrane was washed with methanol and dried at 60°C for 12 hours to produce polythiophene (B). The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polythiophene (B) were approximately 118,000 g / mol and 24,500 g / mol, respectively.

[0363]

[0364] Example 1.

[0365] Formation of polymer layer

[0366] A polymer solution was prepared by mixing the polythiophene (A) of Manufacturing Example 3 and the conductive particles (P) of Manufacturing Example 1 in a weight ratio of 8:2 (A:P) and dispersing the mixture in toluene at a concentration of about 4 wt%. The dispersion was performed using an ultrasonic disperser at a temperature of about 30°C for about 4 hours. The solution was coated on a current collector with a Meyer bar and dried in a drying oven at about 140°C for about 4 minutes (primary heat treatment). Thereafter, the current collector coated with the polymer solution was placed in an oven and heat-treated at 110°C for about 18 hours (secondary heat treatment) to form a layer (polymer layer) having a thickness of about 400 nm. As the current collector, an Al foil having a thickness of about 15 μm was used. The oxidation potential of the polymer layer was about 3.54 V when measured by the method of “4. Measurement of polymer layer oxidation potential.”

[0367]

[0368] Manufacturing of electrodes and electrode assemblies

[0369] A slurry containing LiCoO2, 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 77.5:1:1:20.5 (LiCoO2: conductive material: PVDF: NMP) was applied onto the polymer layer using a doctor blade, and dried at 130°C for 30 minutes to form a slurry layer (slurry loading: approximately 16 mg / cm 2). The layer of the above slurry was rolled to have a porosity of about 18% to form an active material layer with a thickness of about 58 μm to manufacture an electrode. The oxidation potential of the LiCoO2, which is an electrode active material, was about 3.70 V when measured by the method of the above "5. Measurement of oxidation potential of electrode active material". The electrode was used as a positive electrode, and an electrode assembly was manufactured by laminating it with a separator and a negative electrode. The electrode assembly was manufactured by sequentially laminating a positive electrode, a separator, and a negative electrode, and the separator and the negative electrode were formed using the method of the above "12. Oxidation potential V i and V f The separator (SRS) and cathode (lithium film) used in the measurement of " were used. Figure 5 is an SEM image of the electrode.

[0370]

[0371] Example 2.

[0372] Except that the polythiophene (B) of Preparation Example 4 was used instead of the polythiophene (A) of Preparation Example 3 when preparing the polymer solution, and the polythiophene (B) and the conductive particles (P) of Preparation Example 1 were mixed in a weight ratio (B:P) of 6:4, a polymer layer was formed in the same manner as in Example 1, and an electrode and an electrode assembly were manufactured using the same. The oxidation potential of the polymer layer was approximately 3.47 V when measured by the method of "4. Measurement of polymer layer oxidation potential."

[0373]

[0374] Comparative Example 1.

[0375] Polythiophene (A) of Manufacturing Example 3 was dispersed in toluene using an ultrasonic disperser at a temperature of about 30°C for about 4 hours to prepare a solution (concentration: about 4 wt%). The solution was coated on a current collector with a Meyer bar and dried in a drying oven at about 140°C for about 4 minutes to form a polymer layer (same thickness as in Example 1). As the current collector, an Al foil having a thickness of about 15 μm was used. The oxidation potential of the polymer layer was about 3.82 V when measured by the method of "4. Measurement of polymer layer oxidation potential." An electrode and an electrode assembly were manufactured in the same manner as in Example 1 using the laminate (current collector / polymer layer).

[0376]

[0377] Table 1, "12. Oxidation potential V i and V f Oxidation potential V according to "measurement of i and V f , and the rate of change △V1 is expressed as 100×(V f- V i ) / V i It is calculated and organized as shown in Table 1. The oxidation potential V i and V f The unit of is V, and the unit of △V1 is %.

[0378] Example 1 Example 2 Comparative Example 1 Vi 3.46 7 3.46 8 3.72 3 V f 3.49 7 3.5 1 3 3.85 8 △ V 10.87 1.3 3.63

[0379]

[0380] From Table 1, the polymer layer of the example has an oxidation potential V i is low, and the oxidation potential V i Wow V f It can be confirmed that the deviation is also small. These results mean that the electrical properties (oxidation potential, etc.) of the polymer layer are stably maintained even after repeated charge / discharge processes.

[0381]

[0382] Oxidation potential of the polymer layer of the above examples and comparative examples (measured in the manner of “4. Measurement of polymer layer oxidation potential”) (V s ) and the oxidation potential of LiCoO2, an electrode active material (measured in the manner of “5. Measurement of oxidation potential of electrode active material”) (V a ) are summarized and described in Table 2 below. △V2 in Table 2 is the oxidation potential V s and V a The equation is 100 × (V a - V s ) / V a This is the value obtained by substituting it into . Table 2 also summarizes and describes the measurement results of “6. DC resistance measurement method,” “7. AC impedance resistance,” “8. Maximum resistance change rate measurement (DC resistance),” and “9. Maximum resistance change rate measurement (AC impedance).”

[0383] In Table 2, Reference Example 1 is a case where an electrode manufactured in the same manner as Example 2 was applied, except that the ratio of polythiophene (B) and conductive particles (P) was 5:5, and Reference Example 2 is a case where an electrode manufactured in the same manner as Example 2 was applied without forming a polymer layer.

[0384] Example Comparative Example Reference Example 12 1 1 2 Vs 3.5 4 3.4 7 3.7 2 3.4 7 - Va 3.7 3.7 3.7 3.7 3.7 △ V 2 4.3 6.2 - 0.5 6.2 - DC resistance (Ω cm) 8 0 6 5 3 7 0 5 7 4.7 AC impedence (Ω) 10.5 7.7 4 2 6.8 1.7 Formula 3 △ R 1 1 9 8 1 8 4 2 1 0 1 7 0 2.1 On-set (℃) 9 5 1 0 0 9 5 9 5 - Formula 4 △ R 1 1 9 4 1 8 5 2 3.1 1 7 8 2.8 On-set (℃) 9 5 1 0 0 9 5 9 5 -

[0385]

[0386] Table 3 below summarizes the results of "10. Charge / Discharge Test" for the above examples, comparative examples, and reference examples, and Table 4 below summarizes the results of "11. High-temperature discharge capacity reduction rate". In Table 4, the reduction rate is expressed by the formula 100 × (C 25- C130 ) / C 25 This is the result calculated as follows. Conditions 1 to 5 in Table 3 below are conditions 1 to 5 described in the above “10. Charge / Discharge Test.”

[0387] Example Comparative Example Reference Example 12112 Condition 1218.8219.2217.2219.7220.3 Condition 2218.6219.1216.9219.4220.1 Condition 3196.4197.0194.2197.5198.0 Condition 4192.4193.1190.4193.4194.0 Condition 5185.8186.7178.4187.1187.4

[0388] Example Comparative Example Reference Example 12112C25218.8219.2217.2219.7220.3C1302238.520.545.8168.5 Reduction Rate 89.982.490.679.223.5

[0389]

[0390] From Table 3, it can be seen that the electrodes of the examples exhibit performance equivalent to that of Reference Example 2, to which the polymer layer was not applied, but in the case of Comparative Example 1, a potential drop occurs during discharge due to an increase in the C-rate. Reference Example 1, in which the content of conductive particles was increased, also exhibited performance similar to that of the examples. From Table 4, it can be seen that the examples and Reference Example 1 exhibit a high decrease in discharge capacity under high temperature conditions, so that stability can be secured.

[0391]

[0392] Table 5 shows the R measured in the manner described in the above items “13. AC impedance resistance measurement at 3 V and 3.5 V” and “14. AC impedance resistance measurement at room temperature (25 °C) and 130 °C”. 3V , R 3.5V , R 25 and R 130 The results are summarized. In Table 5, Q is the R above. 3V to R 3.5V The value divided by (R 3V / R 3.5V) and P is R 130 R 25 The value obtained by dividing by (R) 130 / R 25 ) is. In Table 4, R 3V , R 3.5V , R 25 and R 130 The unit is Ω.

[0393] Example 1 Example 2 Comparative Example 1 R3 V 39,000 38,000 40,000 R3.5 V 400 350 35,000 Q 97.5 108.6 1.1 R2 5 40 33 800 R1 3 0 34,000 32,000 40,000 P 8 5 0 96 9.750

[0394]

[0395] In Table 5, the embodiment shows that the impedance reduction ratio (Q) confirmed when the external voltage increases from 3 V to 3.5 V is significantly higher than that of the comparative example, which supports the excellent electrical reactivity. The low AC impedance resistance at room temperature (25 °C) means that the charge flow can be stably achieved in the steady state through the polymer layer. In addition, the high AC impedance resistance value measured at high temperature (130 °C) may mean that the PTC characteristics are excellently expressed.

[0396]

[0397] Test Example 1.

[0398] The evaluation was conducted using the electrode of the example and the reference electrode (electrode of Reference Example 2 in Table 2). The thickness of the active material layer of the reference electrode was adjusted so that the electrode of the example and the reference electrode had the same thickness. The rate capability of the electrode of the example and the reference electrode was compared. The rate capability was confirmed by a galvanostatic cycling test, in which the C-rate was increased from 0.1C to 2C.

[0399] Figures 6 to 10 show the results of the above tests. In each figure, SC20 is the result of Example 1, SC40 or SFL is the result of Example 2, and Ref is the result for the reference electrode.

[0400] Figure 6 shows the results for a coin half-cell. In Figure 6, the colored squares, circles, and triangles represent capacity, and the uncolored squares, circles, and triangles represent Coulombic efficiency.

[0401] Figure 7 is the Charge / Discharge profile of the cycle test.

[0402] Figure 8 shows the results of energy density retention (140 cycles).

[0403] Figure 9 shows the rate test results of a 3-Ah pouch cell.

[0404] Figure 10 shows the results of a cycle test of a 3-Ah pouch cell.

[0405] From the drawing, the electrode of Example 2 has 179.5 mAhg- 1 It can be confirmed that the initial discharge capacity and capacity loss of less than 1.2% were shown. In the case of the electrode of the example, the capacity gap was maintained at 2.2% or less even at 2C, and it can be confirmed from this that there is almost no capacity reduction due to the polymer layer under typical battery operating conditions. The energy density retention of the electrodes of examples 1 and 2 was 92% and 95%, respectively, after 140 cycles, which corresponds to a slight difference from the reference electrode (Figs. 7 and 8).

[0406] A 3-Ah pouch cell using the electrode of the example as the anode and a 3-Ah pouch cell using the reference electrode as the anode were each assembled.

[0407] The above positive electrodes were each manufactured in the following manner.

[0408] <Electrode of the embodiment>

[0409] A polymer layer was formed on both sides of the same current collector as used in Example 2 in the same manner as in Example 2, and a positive electrode active material layer was formed on each of the polymer layers in the same manner as in Example 2, thereby manufacturing an electrode of the example. The positive electrode active material layer was formed so that the loading density was approximately 24.29 mg / cm and the porosity was approximately 3.99 g / cc.

[0410] <Reference electrode>

[0411] The positive electrode, which is the reference electrode, was manufactured in the same manner as the electrode of the above example, but without forming a polymer layer, it was manufactured by forming a positive electrode active material layer on each side of the current collector.

[0412] The cathode for the 3-Ah pouch cell was manufactured in the following manner.

[0413] <Cathode>

[0414] The negative electrode was manufactured by forming a negative electrode active material layer on both sides of a copper foil (thickness: approximately 8 μm). The negative electrode active material layer was formed to have a loading density of approximately 13.88 mg / cm and a porosity of approximately 1.75 g / cc. Water (I), SBR (Styrene-Butadiene rubber) (average particle diameter (D50 particle diameter): 150 nm) (II), a thickener (CMC, carboxymethyl cellulose) (III), electrode active material (1) (IV) (artificial graphite (GT), average particle diameter (D50 particle diameter): 20 μm), and electrode active material (2) (V) (natural graphite (PAS), average particle diameter (D50 particle diameter): 15 μm) were mixed in a weight ratio of 48.5:1:0.5:45:5 (I:II:III:IV:V) to prepare a slurry. The above slurry was applied to the surface of the Cu foil to a thickness of about 280 μm by gap coating, dried at about 75°C for about 10 minutes, and then rolled to form the active material layer.

[0415] A stack cell was manufactured by stacking 14 cathodes and 13 anodes. The electrode of the above example or the reference electrode was used as the anode. A separator was positioned between the cathode and the anode. The SRS separator applied in the example was used as the separator. The 3-Ah pouch cell was manufactured using the stack cell and electrolyte. The electrolyte was GTHR KOREA's electrolyte (1 M LiPF6 solution, solvent = EC:DMC:DEC (3:3:4, volume ratio) (EC: Ethylene Carbonate, DMC: dimethyl carbonate, EMC: ethylmethyl carbonate)) (3 μL mAh-1), and an envelope-type pouch (DNP, D-EL408PH(3)) was used as the case. The pouch cell was manufactured to have a width and height of 50 mm and 90 mm, respectively.

[0416] The difference in capacity between the reference electrode and the electrode of the example remained less than 1.5% when cycled from 0.1C to 2.5C. In the case of the electrode of the example, the capacity retention in the recovery cycle after 300 cycles was 97%, which was consistent with the reference electrode. These results confirm that the gravimetric / volumetric energy density and power density in a practical battery are maintained even when the polymer layer is introduced.

[0417]

[0418] Test Example 2.

[0419] A nail penetration test was performed to measure the temperature surge by inserting a nail into a battery. A nail made of SUS (diameter: approximately 2.5 mm, nail tip angle: 60 degrees) was inserted into the center of the 3-Ah pouch cell manufactured in Test Example 1 to determine whether the 3-Ah pouch cell ignited. The penetration was performed by moving the nail at a speed of approximately 50 mm / sec. In the case of the 3-Ah pouch cell with the reference electrode introduced, ignition was confirmed in more than 6 of the 10 3-Ah pouch cells subjected to the test, but in the case of the 3-Ah pouch cell with the electrode of the example applied, ignition was confirmed in only 1 of the 10 3-Ah pouch cells subjected to the test.

[0420]

[0421] Test Example 3.

[0422] Using the 3-Ah pouch cell manufactured in Test Example 1, an impact test was performed to examine how the stability of the battery is improved under mechanical abuse conditions.

[0423] The above Impact Test was performed in the manner shown in Fig. 11.

[0424] That is, a temperature measuring device (T) (TC (temperature controller)) was attached to the surface of the 3-Ah pouch cell (1000) with insulating tape, and a rod (2000) was positioned at the center in the vertical direction. The rod (2000) was a rod made of SUS material with a cross-section having a diameter of about 20 mm and a length of about 100 mm. A cylinder (3000) was positioned on the rod (2000). The cross-section of the cylinder (3000) had a diameter (D out ) is a circle with a diameter of about 900 mm, and the center of the circle has a diameter (D in ) is formed with a hole of about 800 mm. After that, an impact test was performed by allowing a spherical SUS material impact ball (4000) (weight: about 9.1 kg) with a diameter of about 750 mm to fall freely from a height of about 610 mm through the hole in the center of the cylinder (3000) toward the 3-Ah pouch cell (1000).

[0425] The above Impact Test was performed at 100% SOC (State of Charge).

[0426] A test was conducted on 19 3-Ah pouch cells each with a reference electrode and an electrode of the example introduced. In the case of introducing a reference electrode, 12 out of 19 3-Ah pouch cells exploded, whereas in the case of 3-Ah pouch cells with the electrode of the example introduced, 17 out of 19 remained intact. The 3-Ah pouch cells that did not explode were disassembled, and the condition of each component was examined. Among the cells that did not explode, the cathode and anode from the cell with the reference electrode introduced were significantly burnt, and the separator (SRS) was severely deformed. In contrast, in the cells with the electrode of the example introduced that did not explode, each component remained intact even after an external impact.

[0427] Figure 12 shows the temperature change (in situ) measured using a temperature controller (TC) (T) attached to the external surface of the pouch cell. Upon ignition, the temperature rose very rapidly at up to 59°C / sec due to a cascade exothermic reaction between battery components (ignited).

[0428] Even in the absence of explosion, pouch cells with reference electrodes (w / o SRL) experienced localized heating, which was attributed to structural deformation from the impact-induced intense current flow. The temperature rise in pouch cells with reference electrodes introduced and without explosion occurred 1.7 times faster than in pouch cells with the electrodes of the example.

Claims

1. Containing an anode; a cathode; and a separator between the anode and the cathode, The above separation membrane includes a porous polymer membrane and an inorganic particle layer, At least one of the positive and negative electrodes comprises a polymer layer, The above polymer layer includes a conductive polymer and a conductive material, An electrode assembly in which the absolute value of △V1 in the following equation 1 is 3% or less: [Formula 1] △V1= 100 × (V f- V i ) / V i V in Equation 1 i is the oxidation potential after one cycle of voltage scanning of the polymer layer, and V f is the oxidation potential after 10 cycles of voltage scanning of the above polymer layer.

2. In the first paragraph, the positive electrode is an electrode assembly including a current collector; a polymer layer formed on the current collector; and a positive electrode active material layer formed on the polymer layer.

3. Including a positive electrode; a negative electrode; and a separator between the positive electrode and the negative electrode, The above separation membrane includes a porous polymer membrane and an inorganic particle layer, The above positive electrode sequentially includes a current collector, a polymer layer, and a positive electrode active material layer, The above polymer layer 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 positive electrode active material. + Electrode assembly with lower oxidation potential compared to reference oxidation potential.

4. In the third paragraph, an electrode assembly in which △V2 of the following formula 2 is greater than 0% and less than or equal to 20%: [Formula 2] △V2= 100 × (V a - V s ) / V a V in Equation 2 a Li / Li of electrode active material + is the reference oxidation potential, V s is Li / Li in the polymer layer + This is the reference oxidation potential.

5. An electrode assembly according to claim 1 or 3, wherein the maximum temperature in the impact test is 200°C or less and the temperature increase rate is 40°C / sec or less.

6. An electrode assembly according to claim 1 or 3, wherein the conductive material comprises a conductive core and a surface layer present on the surface of the core, and the surface layer comprises a polyphenol-based compound.

7. An electrode assembly according to claim 1 or 3, wherein the conductive polymer comprises a long-chain hydrocarbon functional group.

8. An electrode assembly according to claim 1 or 3, wherein the conductive polymer comprises a first hydrocarbon functional group having 10 or more carbon atoms and a second hydrocarbon functional group having 9 or less carbon atoms.

9. An electrode assembly in which the ratio of the total moles of monomer units having a first hydrocarbon functional group and monomer units having a second hydrocarbon functional group in the conductive polymer is 80 mol% or more.

10. An electrode assembly in which the ratio M2 / M1 of the mole number M2 of the second hydrocarbon functional group or monomer unit having the functional group to the mole number M1 of the first hydrocarbon functional group or monomer unit having the functional group in the 8th paragraph is within a range of 0.01 to 100.

11. An electrode assembly in accordance with claim 7, wherein the conductive polymer further comprises a polar functional group.

12. In the 11th paragraph, the polar functional group is an electrode assembly that is a carboxyl group, a hydroxyl group, an amino group, a cyano group, a nitro group, an ether group, or a functional group of the following chemical formula 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 n is a number in the range of 1 to 10.

13. An electrode assembly in which the ratio of the number of moles of a long-chain hydrocarbon functional group or a monomer unit having the functional group in the conductive polymer to the number of moles of a polar functional group or a monomer unit having the functional group is within a range of 1 to 500.

14. An electrode assembly according to claim 1 or 3, wherein the conductive material comprises carbon particles, carbon fibers, graphene, graphite, carbon black, carbon nanotubes, or metal particles.

15. An electrode assembly according to any one of claims 1 to 14; and A secondary battery containing an electrolyte.

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