Electrode assembly

Abstract

Disclosed in the present specification are an electrode assembly and a secondary battery. Disclosed in the present specification is an electrode assembly in which an electrode and a separator called a safety-reinforcing separator (SRS) are combined, exhibiting low resistance and excellent electrical characteristics in a normal state of a secondary battery and rapidly converting into an insulator to thereby secure stability in an abnormal state of the secondary battery. Disclosed also in the present specification is a secondary battery including 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. 10-2024-0030198, 10-2024-0030197, and 10-2024-0030195, 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] For example, secondary batteries used as power sources in transportation vehicles 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] Accordingly, commercialized secondary batteries are equipped with external safety devices (pressure-limited valves, cell-to-cell fire extinguishers, or high thermal insulating materials, etc.), but these safety devices do not effectively respond to dangerous situations such as thermal runaway, or exhibit slow response speeds.

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

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

[0009] As used herein, the term "room temperature" refers to the natural temperature that has not been artificially heated or cooled. Room temperature may be, for example, any temperature within the range of 10°C to 30°C, or a temperature of 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] In this specification, the term atmospheric pressure means natural pressure that has not been artificially pressurized or depressurized, and may typically mean a pressure within a 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 a humidity that has not been artificially adjusted, 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 that incorporates 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. Combining this membrane with the polymer layer described below can significantly improve stability.

[0022] These SRSs are well known.

[0023] The above 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 be formed on both sides of the polymer film (100).

[0024] As the porous polymer membrane, a polymer membrane typically used in SRS can be used. For example, a material that facilitates lithium ion movement and has 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. In addition, 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 Aly 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 0.75 Li 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 in the range of 0.001 μm to 10 μm.

[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 1 μm to 10 μm. The method for manufacturing the above-described SRS is known, and the inorganic particle layer can be formed through such a known method.

[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, a case in which the active material layer (1003) exists only on one side of the current collector (1001) is illustrated, 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] 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.

[0045] 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.

[0046] The conductive polymer included in the above polymer layer is a polymer that exhibits conductivity due to the conjugation system and / or doping of the polymer chain, as is known.

[0047] 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.

[0048] 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.

[0049] By applying such a polymer layer, the electrode assembly can be applied to secondary batteries, etc., and exhibit excellent electrical characteristics including low resistance in a normal state, and can secure stability through an increase in resistance in an abnormal state.

[0050] In order for the polymer layer to exhibit the above-described effect, 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. In order for an electrode to which a polymer layer with the PTC effect is applied to operate stably and ensure stability under abnormal conditions, the oxidation potential of the polymer layer, the electrical characteristics before the resistance increases due to the PTC effect, and the point in time when the resistance increases due to the PTC effect must be adjusted.

[0051] For example, if the oxidation potential of a polymer layer is higher than that of the electrode active material, repeated charging and discharging under normal conditions may occur, and a potential drop may occur during high-speed charging and discharging. Furthermore, if the resistance of the polymer layer is excessively high under normal conditions, charge movement may be restricted, adversely affecting the operation of the secondary battery. Furthermore, if the temperature at which the PTC effect manifests is within the normal temperature range, the performance of the secondary battery may not be properly realized.

[0052] The above polymer layer has a PTC effect, the timing of the PTC effect's expression is controlled, and a stable oxidation potential and electrical characteristics are maintained before the PTC effect's expression.

[0053] To achieve such a PTC effect, a specific conductive polymer can be introduced into the polymer layer. For example, as described below, by applying a conductive polymer having a relatively long hydrocarbon chain (long-chain hydrocarbon functional group) and controlling the drying or annealing temperature during the polymer layer formation process, a suitable PTC effect (e.g., inducing an increase in the resistance of the polymer layer at a desired temperature (the ideal temperature of the battery)) can be secured.

[0054] By introducing a conductive material into the polymer layer and dispersing it uniformly, oxidation potential and electrical properties can be appropriately maintained.

[0055] For example, the polymer layer, the current collector or electrode to which the polymer layer is applied can be provided so that Q in the following equation 1 is within a predetermined range.

[0056] [Formula 1]

[0057] Q = R 3v / R 3.5v

[0058] R in Equation 1 3v is the AC impedance resistance at 25℃ and 3V voltage conditions, and R 3.5vis the AC impedance resistance at the point where the voltage is converted to 3.5 V under the above 25℃ and 3 V voltage conditions and 1 second has passed. The AC impedance resistance R 3V and R 3.5V is the resistance confirmed in a coin cell to which a current collector on which the polymer layer is formed or an electrode manufactured using the current collector is applied, and the measurement method thereof follows the method described in the “4. AC impedance resistance measurement at 3 V and 3.5 V” section of the Examples section of this specification.

[0059] The lower limit of the above Q may be about 5, 10, 15, 20, 25, 30, 35, 40, 50, 60, 70, 80, 90 or 100, and the upper limit may be about 300, 200, 190, 180, 170, 160, 150, 140, 130, 120, 110, 100, 90, 80, 70, 60, 50, 40, 30 or 20. The above Q may be 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 greater than any lower limit arbitrarily selected from the above-listed lower limits and at the same time less than or equal to any upper limit arbitrarily selected from the above-listed upper limits. The fact that a rapid decrease in resistance occurs within a short period of time after changing the voltage conditions from 3 V to 3.5 V indicates excellent electrical reactivity of the polymer layer.

[0060] AC impedance resistance R in Equation 1 3V The upper limit of R may be about 50,000, 45,000, 40,000 or 35,000, and the lower limit may be about 10,000, 20,000, 30,000 or 35,000. 3VThe unit of is Ω, and the range may 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.

[0061] AC impedance resistance R in Equation 1 3.5V The upper limit of R may be about 2,500, 2,000 1,500, 1,000, 800, 600 or 400, and the lower limit may be about 100, 200, 300, 500, 700, 900, 1,100, 1,300 or 1,500. 3.5V The unit of is Ω, and the range may 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.

[0062] The polymer layer may include a conductive material to ensure excellent electrical reactivity. While excellent electrical reactivity can be maintained through the application of the conductive material, the conductive material may increase the surface roughness of the polymer layer. If the surface roughness of the polymer layer is high, uniform formation of an active material layer applied on top of the layer becomes difficult, and the rolling efficiency for electrode manufacturing may be reduced. The polymer layer disclosed in the present specification maintains a stable surface roughness, and this also applies when the polymer layer includes a conductive material.

[0063] The thickness of the polymer layer may be appropriately selected depending on the purpose. For example, the lower limit of the thickness of the polymer layer may be about 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, or 400 nm, and the upper limit may be about 1,000 nm, 900 nm, 800 nm, 700 nm, 600 nm, 500 nm, or 400 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 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 at the same time less than or equal to any upper limit arbitrarily selected from the upper limits listed above.

[0064] For example, the ratio of the arithmetic mean roughness Ra to the thickness of the polymer layer may be within a predetermined range. The upper limit of the ratio of the arithmetic mean roughness Ra to the thickness of the polymer layer may be about 50%, 45%, 40%, 38%, 36%, 34%, 32%, 30%, 28%, 26% or 25%, and the lower limit thereof is not particularly limited, but may be about 0.001%, 0.01%, 0.1%, 1%, 5%, 10%, 15% or 20%. The ratio 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 at the same time less than or equal to any one upper limit arbitrarily selected from the upper limits listed above. The ratio of the arithmetic mean roughness Ra to the thickness (T) of the polymer layer in the above is a value calculated by the formula 100×Ra / T. In addition, the thickness T of the polymer layer applied above is the average thickness of the polymer layer. The thickness of the polymer layer for the above calculation is measured in the manner described in “3. Thickness Measurement” of the Examples section of this specification, and the arithmetic mean roughness is measured in the manner described in “7. Arithmetic Mean Roughness Ra” of the Examples section of this specification.

[0065] For example, the upper limit of the arithmetic mean roughness Ra of the polymer layer may be about 500 nm, 400 nm, 350 nm, 300 nm, 250 nm, 230 nm, 200 nm, 190 nm, 180 nm, 170 nm, 160 nm, 150 nm, 140 nm, 130 nm, 120 nm, 110 nm or 100 nm, and the lower limit may be about 1 nm, 5 nm, 10 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 120 nm, 130 nm, 140 nm or 150 nm. The arithmetic mean roughness Ra is within a range that is less than or equal to any one 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. The arithmetic mean roughness Ra is measured in the manner described in “7. Arithmetic mean roughness Ra” of the Examples section of this specification.

[0066] When a conductive material is incorporated into a polymer layer, the dispersibility of the conductive material can be stably maintained. Therefore, the polymer layer can maintain a uniform surface with low roughness while securing the advantages associated with the application of the conductive material, such as excellent electrical reactivity. This low surface roughness contributes to ensuring scratch resistance, and allows additional layers, such as an active material layer, to be stably formed on the polymer layer, and subsequent processes, such as a rolling process, to proceed stably.

[0067] The polymer layer or the current collector or electrode including the polymer layer exhibits a precisely designed PTC effect, and accordingly, maintains excellent electrical characteristics at a normal temperature, and exhibits a resistance increasing effect in an abnormal state.

[0068] For example, the polymer layer or the current collector or electrode including the polymer layer can be designed so that P in the following equation 2 is within a predetermined range.

[0069] [Formula 2]

[0070] P = R 130 / R 25

[0071] R in Equation 1 130 is the AC impedance resistance at 130℃, and R 25 is the AC impedance resistance at 25℃. The AC impedance resistance R 130 and R 25 is the resistance confirmed in a coin cell to which a current collector layer having the polymer layer formed thereon or an electrode to which a current collector having the polymer layer formed thereon is applied, and the measurement method thereof follows the method described in the “5. AC impedance resistance measurement at room temperature (25°C) and 130°C” section of the Examples section of this specification.

[0072] The lower limit of P in Equation 2 may be about 60, 70, 80, 90 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900 or 950, 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, 1,400, 1,300, 1,200, 1,100, 1,000, 950, It can be about 900, 850, 800, 750, 700, 650, 600, 550 or 500. 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.

[0073] The above polymer layer, the current collector including it, or the electrode including it exhibits a large resistance difference at room temperature (about 25°C) and high temperature (130), which is due to the PTC effect.

[0074] 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.

[0075] For example, AC impedance resistance R in the above equation 2 25 The upper limit of the AC impedance resistance R may be about 700, 650, 600, 550, 500, 450, 400, 350, 300, 250, 200, 150, 140, 130, 120, 110, 100, 90, 80, 70, 60, 50, 45 or 40, and the lower limit is not particularly limited, but may be about 10, 15, 20, 25, 30, 35, 40 or 45, for example. 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 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. Through these characteristics, stable operation or storage of electronic devices in a normal state can be enabled.

[0076] AC impedance resistance R of Equation 2 130The lower limit of the AC impedance resistance R may be about 10,000, 10,200, 10,400, 10,600, 10,800, 11,000, 13,000, 15,000, 17,000, 19,000, 21,000, 23,000, 25,000, 27,000, 29,000 or 31,000, and the upper limit is not particularly limited, but may be about 60,000, 50,000, 40,000, 35,000, 34,000 or 32,000. 130 The unit of is Ω, and the range 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.

[0077] The electrode assembly including the above polymer layer and separator can exhibit excellent stability even against external impact.

[0078] For example, the electrode assembly may exhibit a maximum temperature below a certain level in an impact test.

[0079] The above maximum temperature is the maximum temperature confirmed in the Impact test performed according to Test Example 4 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.

[0080] 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.

[0081] The above maximum temperature and temperature rise rate can be confirmed according to the contents of Test Example 4 of this specification.

[0082] As the current collector of the positive or negative electrode, any current collector commonly used for the positive or negative electrode can be used without any special limitation.

[0083] 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.

[0084] Such a collector may have a thickness typically within the range of 3 μm to 500 μm, but is not limited thereto.

[0085] The polymer layer is present on one or both sides of the above-mentioned collector. As is known, a conductive polymer is a polymer that exhibits conductivity through a conjugated system and / or doping of a polymer chain.

[0086] The above conductive polymer may have a weight average molecular weight within a predetermined range. For example, the lower limit of the weight average molecular weight of the 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 could be around 145,000 or 150,000, and the upper limit could be around 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, 110,000, 100,000, 80,000, 60,000, or 55,000. The unit of the weight average molecular weight is g / mol, and the range 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 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 at the same time less than or equal to any upper limit arbitrarily selected from the upper limits listed above. By using a conductive polymer having the above weight average molecular weight, a polymer layer and electrode having desired properties can be effectively formed.

[0087] The molecular weight distribution of the conductive polymer, i.e., the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), may be within a predetermined range. The lower limit of the molecular weight distribution may be about 2, 2.5, 3, 3.5, or 4, 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; 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 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. By using a conductive polymer having the above molecular weight distribution, a polymer layer, an electrode current collector, and an electrode having desired properties can be effectively formed.

[0088] 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.

[0089] The above conductive polymer may be polythiophene.

[0090] The term polythiophene refers to a polymer containing a certain level or more of thiophene monomer units. The lower limit of the ratio of the thiophene monomer units 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% based on the total monomer units of the polymer, 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 mole number of the total monomer units of the polythiophene. The ratio of the thiophene monomer units 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 at the same time less than or equal to any upper limit arbitrarily selected from the upper limits listed above.

[0091] In this specification, a monomer unit means a form in which a monomer is polymerized and included in a polymer, and a thiophene monomer means a monomer of the thiophene series and a monomer containing a thiophene skeleton.

[0092] 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 conductive polymer may be polythiophene. In this case, the monomer having the long-chain hydrocarbon functional group may be a thiophene monomer.

[0093] 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.

[0094] 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 number of carbon atoms is within a range that is equal to or greater than any one of the lower limits described above; Or, it may be within a range that is less than or equal to any one of the upper limits described above, and greater than or equal to any one of the lower limits described above.

[0095] 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.

[0096] 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.

[0097] 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).

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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%, or 90 mol%, and the upper limit may be about 98 mol%, 95 mol%, 90 mol%, 85 mol%, 80 mol%, 75 mol%, 70 mol%, 65 mol%, or 60 mol% relative to the molar number of the total monomer units of the polythiophene. The ratio is within a range that is equal to or greater than any one of the lower limits described above; Or, it may be within a range that is less than or equal to any one of the upper limits described above, and greater than or equal to any one of the lower limits described above.

[0103] 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).

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] As described above, the carbon number of the long-chain hydrocarbon functional group is related to the vibration characteristics due to applied heat energy, and when the carbon number changes, the vibration characteristics also change, and the vibration characteristics are further linked to the PTC characteristics of the conductive polymer. In the conductive polymer of the present application, 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.

[0109] 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.

[0110] The ratio of the number of moles (M2) of the second hydrocarbon functional group in the conductive polymer to the number of moles (M1) of the first hydrocarbon functional group (M2 / M1); Alternatively, the lower limit of the ratio (M2 / M1) of the mole number (M2) of the monomer unit having the second hydrocarbon functional group to the mole number (M1) of the monomer unit having the first hydrocarbon 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.

[0111] 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.

[0112] 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.

[0113] As used herein, the term "polar functional group" refers to a functional group containing one or more polar atoms, such as oxygen and / or nitrogen. Examples of such 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.

[0114] [Chemical Formula 1]

[0115]

[0116] 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.

[0117] 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.

[0118] 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.

[0119] In this specification, the term alkylene group means a divalent functional group formed by the removal of hydrogen atoms from two different carbon atoms in an alkane, and the term alkylidene group means a divalent functional group formed by the removal of two hydrogen atoms from one carbon atom in an alkane.

[0120] The alkylene groups of L2 and L1 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.

[0121] The alkylidene groups of L2 and L1 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.

[0122] 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 one of the upper limits described above, and greater than or equal to any one of the lower limits described above.

[0123] 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.

[0124] 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.

[0125] 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, 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 or 20. 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.

[0126] In the conductive polymer, the above unit A(M A ) of the above unit B moles (M B ) for the ratio (M A / M B ) may be about 1, 5, 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 or 20. 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.

[0127] 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.

[0128] 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.

[0129] For example, the conductive polymer may include a unit of the following chemical formula 2 as the thiophene unit.

[0130] [Chemical Formula 2]

[0131]

[0132] 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.

[0133] [Chemical Formula 3]

[0134]

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] [Chemical Formula 4]

[0143]

[0144] 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.

[0145] In another example, R6 and R7 can be linked to each other to form a divalent functional group of the following chemical formula 5.

[0146] [Chemical Formula 5]

[0147]

[0148] 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.

[0149] 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.

[0150] The above conductive polymer may also include a monomer unit represented by the following chemical formula 6.

[0151] The monomer unit of the above chemical formula 6 may be an example of a monomer unit having the second hydrocarbon functional group.

[0152] [Chemical Formula 6]

[0153]

[0154] 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.

[0155] 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.

[0156] [Chemical Formula 7]

[0157]

[0158] 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.

[0159] 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.

[0160] 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.

[0161] [Chemical Formula 8]

[0162]

[0163] 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.

[0164] 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.

[0165] [Chemical Formula 9]

[0166]

[0167] 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.

[0168] 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.

[0169] 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.

[0170] In addition, in the above case, the molar ratio of the monomer unit of the chemical formula 4 and the monomer unit of the 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 chemical formula 4, and the molar number M2 can be the molar number of the monomer unit of the chemical formula 6.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] The polymer layer may contain only the conductive polymer, or may additionally contain the conductive polymer and other necessary additives. In one example, the lower limit of the content of the conductive polymer in the polymer layer may be about 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95 based on the total weight of the polymer layer, and the upper limit may be about 100, 95, 90, 85, 80, 75, 70, 65, 60, 55, or 50 based on the total weight of the polymer layer. The unit of the content is weight%. The range of the content 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.

[0175] For example, the polymer layer may additionally include a conductive material together with the conductive polymer. As the conductive material, a material having appropriate conductivity may 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.

[0176] As the above-mentioned conductive material, an appropriate type may be selected and used from among the above, and the form of the material may be, but is not limited to, particle-like (spherical, irregular or other shapes), plate-like or fiber-like.

[0177] 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. The size may be within a range that is greater than or equal to any lower limit selected from the lower limits listed above; or within a range that is less than or equal to any upper limit selected from the upper limits listed above; or within a range that is greater than or equal to any lower limit selected from the lower limits listed above and less than or equal to any upper limit selected from the upper limits listed above.

[0178] The above size may be the average particle diameter (so-called D50 particle diameter) when the conductive material is in particle form, the thickness, long side or cross-section when the conductive material is in plate form, and the diameter or length of the cross-section when the conductive material is in fiber form.

[0179] 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 greater than or equal to any lower limit arbitrarily selected from the lower limits listed above; 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.

[0180] If necessary, the conductive material may be surface-treated to take dispersibility, etc. into consideration.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] When the above conductive material is used, the ratio of the conductive material within the polymer layer can be adjusted according to the purpose. For example, the lower limit of the weight ratio (parts by weight) of the conductive material relative to 100 parts by weight of the conductive polymer in the polymer layer may be about 0.1 parts by weight, 0.5 parts by weight, 1 parts by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 40 parts by weight, 50 parts by weight, 60 parts by weight, or 65 parts by weight, and the upper limit may be about 1,000 parts by weight, 800 parts by weight, 600 parts by weight, 400 parts by weight, 350 parts by weight, 300 It can be about 250 parts by weight, 200 parts by weight, 150 parts by weight, 100 parts by weight, 90 parts by weight, 80 parts by weight, 70 parts by weight, 60 parts by weight, 50 parts by weight, 45 parts by weight, 40 parts by weight, 35 parts by weight, 30 parts by weight, 25 parts by weight, 20 parts by weight or 15 parts by weight. The content 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 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 at the same time less than or equal to any upper limit arbitrarily selected from the upper limits listed above.

[0185] Under such a ratio, the conductive material can appropriately interact with the conductive polymer to effectively form a polymer layer of the desired shape.

[0186] The polymer layer can be manufactured in the following manner. For example, the method for manufacturing the polymer layer can include a step of forming the polymer layer using a polymer solution containing the conductive polymer and, if necessary, the conductive material. In addition, the method for manufacturing can include, for example, a first step of forming a polymer layer precursor containing the conductive polymer and the conductive material, and a step of heat-treating the polymer layer precursor.

[0187] The conductive polymer and conductive material used to form the polymer layer precursor may be any of the conductive polymers and conductive materials described above. The conductive polymers and conductive 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 methods utilizing radical reactions, and these methods can also be applied to the process of forming the conductive polymer in the present application. In addition, commercially available products may be used as the conductive material, and their surface treatment may be performed by known methods.

[0188] The above polymer layer precursor means, for example, a layer including the conductive polymer and conductive particles, and a layer that is ultimately converted into the polymer layer.

[0189] 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.

[0190] As the solvent in the above, 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.

[0191] In the above step, the lower limit of the concentration of the conductive polymer present in the polymer solution may be about 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, or 3 wt%, and the upper limit may be about 20 wt%, 18 wt%, 16 wt%, 14 wt%, 12 wt%, 10 wt%, 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5 wt%, 4 wt%, or 3 wt%. The ratio may be within a range that is equal to or greater than any lower limit arbitrarily selected from the lower limits listed above, or within a range that is equal to or less than any upper limit arbitrarily selected from the upper limits listed above, or within a range that is equal to or less than any upper limit arbitrarily selected from the upper limits listed above and equal to or greater than any lower limit arbitrarily selected from the lower limits listed above. This concentration may be changed as needed.

[0192] The polymer solution described above is used to form a polymer layer 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.

[0193] 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.

[0194] The polymer solution is used to form a polymer layer on a current collector. This process typically involves coating the polymer solution on the current collector and heat-treating the coated coating solution, such as drying or annealing. During this process, the crystallinity of the conductive polymer can also be controlled by the heat treatment conditions.

[0195] 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.

[0196] The conditions of the second and third steps can be adjusted to achieve the desired orientation or alignment of the conductive polymer and the dispersion state of the conductive material.

[0197] 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.

[0198] 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 or 1, and the upper limit can be about 10, 8, 6, 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.

[0199] 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.

[0200] The ratio of the heat treatment time Q1 in the first heat treatment and the heat treatment time Q2 in the second heat treatment can be additionally adjusted. For example, the lower limit of the ratio Q2 / Q1 may be about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 50, 100, 150, 200 or 250, and the upper limit may be about 1,000, 800, 600, 400, 300, 280, 250, 200, 150, 100, 90, 80, 70, 60, 50, 40, 30, 20, 19, 18, 17, 16 or 15. The ratio Q2 / Q1 is within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above; Or within a range that is less than or equal to any upper limit arbitrarily selected from the upper limits listed above; or within a range that is greater than or equal to any lower limit arbitrarily selected from the lower limits listed above and less than or equal to any upper limit arbitrarily selected from the upper limits listed above.

[0201] The lower limit of the above secondary heat treatment time Q2 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 Q2 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.

[0202] The polymer layer can be formed through the above process.

[0203] 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.

[0204] For example, through the above process, a desired polymer layer can be formed on a current collector, and an active material layer can be formed on the polymer layer in a conventional manner to obtain the electrode (positive electrode or negative electrode).

[0205] A layer that is commonly applied can also be used as the above active material layer.

[0206] Typically, the above active material layer includes an electrode active material. There is no particular limitation on the specific type of the electrode active material, and typically, a material forming a positive or negative electrode can be used.

[0207] For example, when the active material layer is a positive electrode active material layer, the electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; lithium iron oxide such as LiFe3O4; or a compound having the chemical formula Li 1+c1 Mn 2-c1 Lithium manganese oxides such as O4(0≤c1≤0.33), LiMnO3, LiMn2O3, or LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, or Cu2V2O7; chemical formula LiNi 1-c2 M c2 Ni-site type lithium nickel oxide represented by O2 (wherein, M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, and satisfies 0.01≤c2≤0.3); chemical formula LiMn 2-c3 M c3Lithium 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.

[0208] 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.

[0209] 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.

[0210] 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.

[0211] The above active material layer may additionally include a binder. The binder serves to improve adhesion between active materials and adhesion between the active material layer and the current collector. Examples of the above binder are not particularly limited, and include, for example, PVDF (Poly(vinylidene fluoride)), PVA (poly(vinyl alcohol)), SBR (styrene butadiene rubber), PEO (poly(ethylene oxide)), CMC (carboxyl methyl cellulose), cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, cyanoethylpullulan, cyanoethyl polyvinylalcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, At least one selected from the group consisting of polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, and polyarylate may be used.

[0212] In one example, the binder may be included in the active material layer in an amount of 0.1 to 10 parts by weight or 0.5 to 5 parts by weight relative to 100 parts by weight of the electrode active material, but is not limited thereto.

[0213] 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.

[0214] 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.

[0215] In addition to the components described above, the active material layer may additionally include any known components required.

[0216] 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 applied in the same manner.

[0217] Such an electrode may sequentially include the current collector; a conductive polymer layer and an active material layer.

[0218] The above conductive polymer layer can have a uniform and stable thickness through excellent coating properties as described above.

[0219] Therefore, in the above electrode, the active material layer does not include a protrusion at the end even before rolling. For example, in the above electrode, the active material layer includes a sliding region. The sliding region is a region where the thickness of the active material layer increases along the coating direction at and near the coating start point due to the viscosity characteristics of the slurry when forming the active material layer using the electrode slurry, and a region where the thickness of the active material layer decreases along the coating direction at and near the coating end point.

[0220] This sliding region is a phenomenon that generally occurs during the electrode manufacturing process. For example, as exemplarily shown in Fig. 4, in order to manufacture an electrode, the conductive polymer layer (200) is formed on a current collector (100), and the electrode slurry is coated thereon to form an active material layer (300). In this case, if the coating direction is from the left to the right of Fig. 4, a sliding region (S) in which the thickness of the active material layer (300) increases from the start of the coating to a certain region is created, and after a certain period of time, a region (N) in which the thickness is stabilized appears, and then a sliding region (S) in which the thickness decreases again occurs in a certain region (3002).

[0221] However, if a protrusion occurs within the sliding region (S), a problem occurs in the subsequent electrode manufacturing process. The protrusion refers to a region between the regions (3001, 3002) excluding the start and end regions (3001, 3002 in the case of FIG. 4) of the sliding region (S), and is formed thicker than the start and end regions (3001, 3002 in the case of FIG. 4).

[0222] If such protrusions exist, problems arise during the rolling process of the subsequent active material layer.

[0223] Since the conductive polymer layer is formed with a stable and uniform thickness, the maximum thickness in the thickness profile of the sliding region is confirmed at the end point of the sliding region. In this case, the end point of the sliding region means the thicker point among the start and end points (3001 and 3002 in the case of Fig. 4) of the sliding region (S).

[0224] The above-mentioned active material layer does not include the protrusions at the ends even when it is an unrolled active material layer, i.e., an active material layer before rolling. When the above-mentioned rolling is performed, even if there are some protrusions, there is a possibility that the protrusions will disappear, but in the process, damage to the current collector, etc. may occur, or uneven rolling may be performed. Since the active material layer of the electrode does not have protrusions in the unrolled state, the above-mentioned rolling process can also be performed efficiently. Such an active material layer can be included in the above-mentioned electrode assembly after undergoing the rolling process.

[0225] The conductive polymer layer of the above electrode may be an unsurfaced conductive polymer layer. That is, even when the active material layer is formed without performing surface treatment such as corona treatment or plasma treatment on the conductive polymer layer, a sliding region without protrusions can be stably formed.

[0226] The electrode assembly can be formed using the positive and negative electrodes formed in the above manner and the separator described above.

[0227] 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.

[0228] 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.

[0229] Figure 1 is a side view of an exemplary electrode assembly.

[0230] Figure 2 is a side view of an exemplary membrane.

[0231] Figure 3 is a side view of an exemplary electrode.

[0232] Figure 4 is a cross-sectional view of an electrode for explaining the sliding area.

[0233] Figure 5 shows the NMR analysis results of the compound manufactured in the manufacturing example.

[0234] Figure 6 is an SEM image of the electrode of the embodiment.

[0235] Figure 7 is a thickness profile of the sliding region of the active material layer of the electrode.

[0236] Figure 8 shows the analysis results for Coin Haspel of Test Example 1.

[0237] Figure 9 is a charge / discharge profile of the cycle test of Test Example 1.

[0238] Figure 10 shows the results of energy density retention (140 cycles) of Test Example 1.

[0239] Figure 11 shows the rate test results of the 3-Ah pouch cell of Test Example 1.

[0240] Figure 12 shows the results of a cycle test of the 3-Ah pouch cell of Test Example 1.

[0241] Figure 13 is a drawing for explaining a method for performing an impact test.

[0242] Figure 14 is a diagram showing the maximum temperature and temperature rise rate of the impact test.

[0243] The contents of the electrode assembly are specifically described through the following examples and comparative examples, but the scope of the electrode assembly, etc. is not limited by the following examples.

[0244]

[0245] 1. NMR analysis method

[0246] 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 a solvent for NMR measurement (CDCl3) to a concentration of approximately 10 mg / ml, and chemical shifts were expressed in ppm. .

[0247]

[0248] 2. GPC (Gel Permeation Chromatograph)

[0249] 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.

[0250] <GPC 측정 조건>

[0251] Device: Waters 2414

[0252] Column: Using 3 Styragel from Waters

[0253] Solvent: THF (Tetrahydrofuran)

[0254] Column temperature: 35℃

[0255] Sample concentration: 1 mg / mL, 1 μL injection

[0256] Standard samples: polystyrene (Mp: 3900000, 723000, 316500, 52200, 31400, 7200, 3940, 485)

[0257]

[0258] 3. Thickness measurement

[0259] The thickness of the polymer layer was confirmed using a VK-X series confocal laser microscope from KEYENCE. Aluminum foil with a polymer layer formed on it was cut to 3 cm in width and length to prepare a specimen, and about half of the polymer layer was removed from the specimen with acetone to expose the aluminum foil underneath. The aluminum foil side of the specimen without a polymer layer was pressed against a flat plate, and measurement was started. An area of ​​100 μm in width and length was observed under the microscope, and the polymer layer of the specimen and the exposed aluminum foil were adjusted to be approximately half located within the observation area, and a 3D scan was performed. The average value P of the heights was measured at 10 random points on the polymer layer within the observation area, and the average value A was obtained by measuring the heights at 10 random points on the aluminum foil. The average value A was then calculated by subtracting the average value P from the average value P, which was used as the thickness of the polymer layer.

[0260]

[0261] 4. AC impedance resistance measurement at 3 V and 3.5 V

[0262] Sample production

[0263] A polymer layer was formed on aluminum foil (Al Foil) with a thickness of 15 μm. The method for forming the polymer layer, the thickness, etc., are the same as those described in each of the Examples and Comparative Examples. Thereafter, 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. Coin cells were manufactured using the laminate and the electrolyte punched into a circle (Wellcos CR2032 coin cell kit), and the impedance of the coin cells was measured. The separator used was LG Energy Solution's SRS (safety-reinforcing separator). The above SRS is a separator in which an inorganic particle layer including PVDF-HFP (Poly(vinylidene fluoride-co-hexafluoropropylene) and Al2O3) is formed on a polymer membrane (polyethylene membrane) (porosity of about 45%), and the weight ratio of PVDF-HFP and Al2O3 (PVdF-HFP:Al2O3) is about 1:4. A lithium film having a thickness of about 300 μm is used as the lithium film, and an Enchem product (1M LiPF6 solution (solvent: EC / DMC / EMC=3 / 4 / 3 (mass ratio), EC: Ethylene Carbonate, DMC: dimethyl carbonate, EMC: ethylmethyl carbonate)) is used as the electrolyte.

[0264]

[0265] External voltage 3V condition

[0266] The AC impedance resistance of the coin cell was measured by the EIS (Electrochemical Impedance Spectronization) method. A voltage of 3 V was applied to the coin cell for 10 minutes at room temperature (25°C), and the interface 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 was measured. 3V was measured. A potentiostat (Princeton Applied Research, PARASTAT-MC) was used as the EIS measuring device.

[0267]

[0268] External voltage 3.5V condition

[0269] 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.

[0270]

[0271] 5. AC impedance resistance measurement at room temperature (25℃) and 130℃

[0272] The AC impedance resistance was measured using the same coin cell used in "4. AC impedance resistance measurement at 3 V and 3.5 V." The AC impedance resistance of the coin cell was measured using the EIS (Electrochemical Impedance Spectronization) method. Specifically, the interface resistance obtained in the high frequency region was measured from the Nyquist plot obtained by the EIS measurement method in the range of 50,000 Hz to 0.1 Hz. The EIS measurement device used was a potentiostat (Manufacturer: Princeton Applied Research, Product name: PARASTAT-MC).

[0273] After applying a voltage of 4.5 V at room temperature (25°C) for 10 minutes to the above coin cell to maintain the doping state of the conductive polymer, the AC impedance resistance was measured after about 1 minute with the external voltage set to 0 V (Open circuit voltage). The measured value is the AC impedance resistance R of the polymer layer at room temperature (25°C). 25 was evaluated as .

[0274] 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 as .

[0275]

[0276] 6. Average particle size

[0277] The average particle size (D50 particle size) of the conductive particles 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 (conductive particles) was dispersed in the solvent and a laser was irradiated, the laser was scattered by the sample dispersed in the solvent. Since the intensity and directionality of the scattered laser vary depending on the size of the particles, this can be analyzed using Mie theory to obtain the average particle 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 to obtain a volume-based cumulative graph of the particle size distribution, and the particle diameter at 50% of the cumulative point of the graph (median particle size) was designated as the average particle size (D50 particle size).

[0278]

[0279] 7. Arithmetic mean roughness Ra

[0280] The arithmetic mean roughness Ra was measured using a VK-X series confocal laser microscope from KEYENCE. Polymer-coated aluminum foil was cut to 3 cm in length and width to prepare a specimen. The side of the aluminum foil without the polymer layer was pressed against a flat plate and 3D scanned.

[0281] A polymer layer with a width and height of 100 μm was 3D scanned. After randomly designating an area with a width and height of 50 μm each within the 3D scanned area, the arithmetic mean roughness Ra was measured using the 3D scan image.

[0282]

[0283] 8. Scratch resistance

[0284] Using Mujincheon (Hansong Cheonwiper MIRACLEAN322 Polyester), the surface of the polymer layer was rubbed back and forth 10 times with a load of 100 g and a speed of 27 rpm. If scratches were observed with the naked eye, it was evaluated as X, and if no scratches were observed with the naked eye, it was evaluated as O.

[0285]

[0286] Manufacturing Example 1. Polydopamine-coated conductive particles

[0287] As a challenge particle, carbon black particles (IMERYS, C·NERGY TM SUPER C65) was used. The average particle diameter (D50 particle diameter) of the above challenge particles was approximately 60 nm.

[0288] 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 Biosesangsa. 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 polydopamine coating layer on the conductive particles. After filtering under reduced pressure using a paper filter, the conductive particles coated with polydopamine were obtained by vacuum drying.

[0289]

[0290] Manufacturing Example 2. Synthesis of monomer (A)

[0291] The monomer of the following chemical formula A was synthesized in the following manner.

[0292] [Chemical Formula A]

[0293]

[0294] 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 5.

[0295]

[0296] Manufacturing Example 3. Synthesis of polythiophene (A)

[0297] A conductive polymer was prepared by polymerizing 3-dodecylthiophene (3-DT), 3-hexylthiophene (3-octylthiophene) (3-HT) and the monomer (A) of Chemical Formula A of Preparation Example 2. 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 (B). The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polythiophene (B) were 150,000 g / mol and 50,000 g / mol, respectively.

[0298]

[0299] Manufacturing Example 4. Synthesis of polythiophene (B)

[0300] A conductive polymer was prepared by polymerizing 3-dodecylthiophene (3-DT), 3-octylthiophene (3-OT), and the monomer (A) of Chemical Formula A of Preparation Example 2. To a solution of 3.20 g (19.71 mmol, 3 eq) of iron (III) chloride dissolved in 150 ml of methylene chloride, 0.79 g (3.135 mmol, 0.475 eq) of 3-dodecylthiophene, 0.62 g (3.315 mmol, 0.475 eq) of 3-octylthiophene, and 0.081 g (0.33 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 (B). 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 51,200 g / mol and 13,400 g / mol, respectively.

[0301]

[0302] Example 1.

[0303] Formation of polymer layer

[0304] A polymer solution was prepared by mixing the polythiophene (A) of Manufacturing Example 3 and the polydopamine-coated 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%. When preparing the polymer solution, the mixture was dispersed at a temperature of about 30°C for about 4 hours using an ultrasonic disperser. The polymer 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 dried 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.

[0305]

[0306] Manufacturing of electrodes and electrode assemblies

[0307] An electrode was manufactured by forming an active material layer on the polymer layer. The active material layer was formed by applying a slurry containing lithium cobalt oxide (LiCoO2), a carbon-based conductive agent (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 agent: PVDF: NMP) onto the polymer layer using a doctor blade, and drying at 130°C for 30 minutes (slurry loading: approximately 16 mg / cm 2). The active material layer of the above electrode 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. Fig. 6 is an SEM image of the electrode. 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 the positive electrode, separator, and negative electrode. As the separator, the separator (SRS) used in the above "AC impedance resistance measurement at 4.3 V and 3.5 V" was used, and as the negative electrode, a graphite negative electrode was used.

[0308]

[0309] Example 2.

[0310] Except that the polythiophene (A) of Manufacturing Example 3 and the polydopamine-coated conductive particles (P) of Manufacturing Example 1 were mixed in a weight ratio (A:P) of 6:4 during the preparation of the polymer solution, 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.

[0311]

[0312] Example 3.

[0313] Except that polythiophene (B) of Preparation Example 4 was used instead of polythiophene (A) of Preparation Example 3 when preparing a polymer solution, a polymer layer was formed in the same manner as in Example 1, and an electrode and electrode assembly were manufactured using the same. At this time, the temperature was set to 130°C and the time was set to 60 minutes during the second heat treatment.

[0314]

[0315] Example 4.

[0316] Except that polythiophene (B) of Manufacturing Example 4 was used instead of polythiophene (A) of Manufacturing Example 3 in the preparation of the polymer solution, a polymer layer was formed in the same manner as in Example 2, and an electrode and electrode assembly were manufactured using the same.

[0317]

[0318] Example 5.

[0319] In the production of a polymer solution, carbon black particles (CERGY) not coated with polydopamine were used instead of the polydopamine-coated conductive particles (P) of Production Example 1. TM A polymer layer was formed in the same manner as in Example 1, except that SUPER C65 was used, and an electrode and electrode assembly were manufactured using the same.

[0320]

[0321] Example 6.

[0322] In the production of a polymer solution, carbon black particles (CERGY) not coated with polydopamine were used instead of the polydopamine-coated conductive particles (P) of Production Example 1. TM A polymer layer was formed in the same manner as in Example 2, except that SUPER C65 was used, and an electrode and electrode assembly were manufactured using the same.

[0323]

[0324] Comparative Example 1.

[0325] Formation of polymer layer

[0326] Polythiophene (A) of Manufacturing Example 3 was dispersed in toluene at a concentration of about 4 wt% to prepare a polymer solution. When preparing the polymer solution, the polythiophene was dispersed at a temperature of about 30°C for about 4 hours using an ultrasonic disperser. The polymer solution was coated on a current collector using 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 dried at 130°C for about 60 minutes (secondary heat treatment) to form a polymer layer (same thickness as Example 1). As the current collector, an Al foil having a thickness of about 15 μm was used.

[0327]

[0328] Manufacturing of electrodes and electrode assemblies

[0329] An electrode was manufactured by forming an active material layer on the polymer layer. The active material layer was formed by applying a slurry containing lithium cobalt oxide (LiCoO2), a carbon-based conductive agent (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 agent: PVDF: NMP) onto the polymer layer using a doctor blade, and drying at 130°C for 30 minutes (slurry loading: approximately 16 mg / cm 2 ) The active material layer of the above electrode was rolled to have a porosity of approximately 18% to form an active material layer with a thickness of approximately 58 μm, thereby manufacturing an electrode. Using the above electrode as an anode, an electrode assembly was manufactured in the same manner as in Example 1.

[0330]

[0331] Tables 1 and 2 show the R values ​​measured by the method described above for examples and comparative examples. 3V , R 3.5V , R 25 , R 130 , the results of the arithmetic mean roughness Ra and scratch resistance evaluation are summarized. In Tables 1 and 2 below, R 3V , R 3.5V , R 25 and R 130 The unit of is Ω, and the unit of the arithmetic mean roughness Ra is nm.

[0332] In Tables 1 and 2, Q is the above R 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 )am.

[0333] Reference Example 1 of Table 2 is a case where a polymer layer is formed in the same manner as Example 1, and an electrode and an electrode assembly are manufactured, but the weight ratio (A:P) of the polythiophene (A) of Manufacturing Example 3 and the polydopamine coated conductive particle (P) of Manufacturing Example 1 is 9:1.

[0334] Example 123456R3V35,00038,00036,50038,50034,00038,000R3.5V400350370340350300Q87.5108.698.6113.297.1126.7R25453340304235R13030,00032,00031,00031,50030,00033,000P666.7969.77751,050714.3942.9Ra130150130150250300Scratch resistance○○○○××

[0335] Comparative Example 1 Reference Example 1 R3V40,000 36,000 R3.5V35,000 1,800 Q1.120 R25800 60 R130 40,000 30,000 P50500 Ra50100 Scratch Resistance ○○

[0336]

[0337] From the results in Tables 1 and 2, in the case of the examples, the decrease ratio (Q) of the impedance confirmed when the external voltage increases from 3 V to 3.5 V is significantly higher than that of the comparative examples, which supports the excellent electrical reactivity. As a conductive material, when conductive particles surface-treated with a specific material are applied, it can be seen that even if the content of the conductive material is increased, low surface roughness is maintained, and scratch resistance can also be stably secured. In the case of the examples, the room temperature impedance (R 25 ) based on high temperature impedance (R 130 ) is also very high, so it can be confirmed that the PTC effect is stably exhibited.

[0338]

[0339] Test Example 1.

[0340] A cross-section of the electrode before rolling (a cross-section of the electrode having a cross-sectional schematic diagram of Fig. 4) was photographed using a confocal laser microscope to obtain a thickness profile of the active material layer (300) from the beginning (edge ​​part) (3001) of the sliding region (S) to the end point (3002) of the sliding region (S), and the results are summarized in Fig. 7.

[0341] In the graph of Fig. 7, the x-axis represents the distance (unit: μm) from the starting point of the sliding area (S) (3001 in Fig. 2) to any point within the range from that point to the ending point (3002) of the sliding area (S), with 0 being the starting point, and the y-axis represents the thickness (unit: μm) of the active material layer (300 in Fig. 4) at each point.

[0342] In Fig. 7, the ● marked line is for Example 1, the ▲ marked line is for Example 2, the ▼ marked line is for Comparative Example 1, the ◆ marked line is for Reference Example 2, and the ■ marked line is for Reference Example 3.

[0343] The above Reference Example 2 is a case where an electrode and electrode assembly are manufactured in the same manner as Comparative Example 1, but corona treatment (discharge current condition: approximately 200 mA) is performed on the polymer layer before forming the active material layer, and Reference Example 3 is a case where an electrode is manufactured in the same manner as Example 1, but the electrode active material layer is formed directly without forming the polymer layer.

[0344] As shown in Fig. 7, in the case where the active material layer is formed directly on the surface of the current collector without forming a polymer layer to obtain the PTC (positive temperature coefficient) effect (Reference Example 3), no protruding portion occurs, but in the case where the polymer layer is formed (Comparative Example 1), it can be confirmed that a protruding portion is formed at the middle point of the sliding area (approximately 200 μm to 1200 μm in the drawing). This causes damage to the electrode in the subsequent rolling process, resulting in problems such as a decrease in electrode performance or difficulty in electrode application. However, the protruding portion did not occur in the case where the surface properties of the conductive polymer layer were adjusted through corona treatment (Reference Example 2).

[0345] In the case of Examples 1 and 2, it can be confirmed that the protruding portion does not occur by forming a polymer layer for the PTC effect and by adjusting the surface properties and securing the coating property through the introduction of specific conductive particles even when the conductive polymer layer is not subjected to a separate corona treatment.

[0346] Table 3 below summarizes the results of the above drawing in numerical form.

[0347] In Table 3, the distance (μm) is the x-axis coordinate of Fig. 7, and the thickness (μm) at each x-axis coordinate is organized and described.

[0348] Distance (μm)Example 1Example 2Comparative Example 1Reference Example 2Reference Example 350211418171610026275530292004543.58444.5443005853935756.5500696710366.5687007876.5105797790082.5811028380110085.585948584130086869085.585

[0349]

[0350] Test Example 2.

[0351] The evaluation was conducted using the electrode of the example and the reference electrode (electrode of Reference Example 3 of Test Example 1). 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 through a galvanostatic cycling test, in which the C-rate was increased from 0.1C to 2C.

[0352] Figures 8 to 12 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.

[0353] Figure 8 shows the results for a coin half-cell, where the circular symbol represents capacity and the square symbol represents Coulombic efficiency.

[0354] Figure 9 is the Charge / Discharge profile of the cycle test.

[0355] Figure 10 shows the results of energy density retention (140 cycles).

[0356] Figure 11 shows the rate test results of a 3-Ah pouch cell.

[0357] Figure 12 shows the results of a cycle test of a 3-Ah pouch cell.

[0358] From the drawing, the electrode of the embodiment is 179.5 mAhg- 1It 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 electrode of the example was 92% and 95% after 140 cycles, respectively, which corresponds to a slight difference from the reference electrode (Figs. 8 and 10).

[0359] 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.

[0360] The above positive electrodes were each manufactured in the following manner.

[0361] <Electrode of the embodiment>

[0362] 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.

[0363] <Reference electrode>

[0364] 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.

[0365] The cathode for the 3-Ah pouch cell was manufactured in the following manner.

[0366] <Cathode>

[0367] 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.

[0368] 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.

[0369] 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.

[0370]

[0371] Test Example 3.

[0372] 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 2 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.

[0373]

[0374] Test Example 4.

[0375] Using the 3-Ah pouch cell manufactured in Test Example 2, an impact test was performed to examine how the stability of the battery is improved under mechanical abuse conditions.

[0376] The impact test was performed at 100% SOC (State of Charge).

[0377] The above Impact Test was performed in the manner shown in Fig. 13.

[0378] 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).

[0379] 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.

[0380] Figure 14 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).

[0381] 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, The above positive electrode includes a current collector and a polymer layer formed on the current collector, The above polymer layer includes a conductive polymer and a conductive material, The above positive electrode is an electrode assembly in which Q of the following formula 1 is 10 or more: [Formula 1] Q = R 3V / R 3.5V R in Equation 1 3V is the AC impedance resistance of the anode at 25℃ and 3V, and R 3.5V is the AC impedance resistance of the anode when the above 25℃ and 3V conditions are changed to 25℃ and 3.5V conditions, and 1 second has elapsed.

2. In the first paragraph, an electrode assembly in which P according to the following formula 2 is 60 or more: [Formula 2] P = R 130 / R 25 R in Equation 2 25 is the AC impedance resistance by the polymer layer at 25℃, and R 130 is the AC impedance resistance of the polymer layer at 130℃.

3. An electrode assembly in accordance with claim 1, wherein the ratio of the arithmetic mean roughness Ra of the polymer layer to the thickness of the polymer layer is 50% or less.

4. An electrode assembly according to claim 1, wherein the arithmetic mean roughness Ra of the polymer layer is 230 nm or less.

5. An electrode assembly in paragraph 1, 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. In the first paragraph, the conductive polymer is an electrode assembly having a long-chain hydrocarbon functional group.

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

8. 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 in the 7th paragraph.

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

10. An electrode assembly in accordance with claim 6, wherein the conductive polymer further comprises a polar functional group.

11. In the 10th 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.

12. In the 10th paragraph, an electrode assembly in which the ratio of the number of moles of monomer units having a long-chain hydrocarbon functional group in the conductive polymer to the number of moles of monomer units having a polar functional group is within the range of 1 to 500.

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

14. An electrode assembly in claim 1, 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.

15. An electrode assembly comprising, in the first paragraph, an anode further including an active material layer formed on a polymer layer.

16. A secondary battery comprising an electrode assembly according to any one of claims 1 to 15.

Images