Method for removing foreign matter from the slitting cutting area of the cathode collector and the cathode collector for the secondary battery by the same method

Abstract

The present invention relates to a method for effectively removing foreign substances generated during the manufacture and processing of an anode current collector and an anode current collector from which foreign substances have been removed by this method. Unlike conventional methods for removing foreign substances from a slit-cut anode current collector through dry cleaning using a dust-free cloth, OPP tape, etc., or wet cleaning using a cleaning solution, the invention provides a method for effectively removing foreign substances using a specific gas.

Description

Technology Field

[0001] The present invention relates to a method for effectively removing foreign substances generated during the manufacture and processing of an anode current collector, and an anode current collector from which foreign substances have been removed by this method. Background Technology

[0003] A secondary battery refers to a battery composed of one or more electrochemical cells capable of charging and discharging. A secondary battery is a battery designed to convert external electrical energy into chemical energy for storage and reuse. Secondary batteries possess high capacity and are advantageous for miniaturization and lightweight design. Due to these characteristics, secondary batteries are utilized in a wide range of fields, from small IT devices and power tools to small home appliances and gardening tools. For example, secondary batteries can include lithium-ion and lead-acid batteries. In the case of lithium-ion batteries, they are applied to mobile IT devices such as chargers, smartphones, laptops, and tablet PCs, and furthermore, to electric mobility devices (cars, ships, airplanes, etc.).

[0004] During the miniaturization process of secondary batteries, the internal components have been developed to occupy less volume while efficiently utilizing internal space. For example, in the case of positive plates or negative plates that store or output electrical energy by absorbing, storing, or releasing ions through redox reactions inside the secondary battery, the manufacturing process is carried out so that their width becomes thin in the micrometer range.

[0005] The positive plate of a secondary battery contains metal material, and the problem of the positive plate breaking occurs during the miniaturization process. In particular, when manufacturing the positive plate and processing it to a specific size, slitting cutting is inevitably performed, and at this time, burrs, which are residues of slitting cutting, are generated on the positive plate.

[0006] When the positive electrode material and the negative electrode material constituting a secondary battery come into direct contact, a fire may occur. The separator of the secondary battery plays a role in blocking the direct contact and reaction between the positive electrode material and the negative electrode material inside the battery cell.

[0007] However, if a large burr remains on the positive current collector, which is one of the positive electrode materials, the separator of the secondary battery may be damaged by the burr, and as a result, there is a problem in that the probability of a fire occurring in the secondary battery increases significantly.

[0008] Accordingly, IEEE 1725, Section 5.3.6 limits the size of burrs remaining in the anode current collector.

[0009] Therefore, in order to apply the anode plate (or anode foil) as an anode current collector, after slitting cutting to process it into a certain size, burrs, which are adhesive foreign substances on the slitting cutting area, are removed by dry cleaning using a dust-free cloth, OPP tape, etc., or by wet cleaning using a cleaning solution, etc. However, these burr removal methods had problems such as low burr removal efficiency or long processing time. Prior art literature

[0011] Korean Published Patent No. 2020-0048068 (Publication Date: May 8, 2020) The problem to be solved

[0012] The present invention provides a method to effectively remove adhesive foreign substances, such as adhesive burrs, generated during the processing of an anode plate (anode foil) which is an anode current collector of a secondary battery, thereby providing an anode current collector that can ensure the stability of the secondary battery by removing foreign substances through the said method. means of solving the problem

[0014] The present invention, for solving the above problem, relates to a method for removing foreign substances from a slitting cut portion of an anode current collector. The method involves removing foreign substances from the slitting cut portion by performing a process of spraying a CO2-containing mixed gas onto the slitting cut portion of the anode current collector. At this time, the slitting cut portion refers to the longitudinal direction of the anode current collector.

[0015] As a preferred embodiment of the present invention, the injection process is performed using a gas injection device equipped with a gas injection nozzle.

[0016] As a preferred embodiment of the present invention, the gas injection device may be equipped with 3 to 5 gas injection nozzles.

[0017] As a preferred embodiment of the present invention, the gas injected through the gas injection nozzle may comprise 90 to 98 volume% of CO2 and the remaining amount of air.

[0018] As a preferred embodiment of the present invention, each of the 3 to 5 gas injection nozzles equipped in the gas injection device is equipped with a CO2 gas inlet and an air inlet, and a mixed gas in which these are mixed can be injected through the gas injection nozzle.

[0019] As a preferred embodiment of the present invention, the temperature of the mixed gas injected may be 90 to 120°C.

[0020] As a preferred embodiment of the present invention, the injection pressure of the mixed gas being injected may be 6.0 to 10.0 bar.

[0021] In a preferred embodiment of the present invention, when the slitting cut anode current collector is wound into a roll, the gas injection device may be installed so that the gas injected from the gas injection nozzle is injected in a vertical direction relative to the side of the roll.

[0022] As a preferred embodiment of the present invention, the vertical direction means that the angle formed by the side of the wound roll and the centerline of the gas injection nozzle is 0° to 15°.

[0023] As a preferred embodiment of the present invention, when the positive current collector is a rolled roll, the gas injection device may be installed on one side or both sides of the slitting cut surface of the roll.

[0024] As a preferred embodiment of the present invention, the anode current collector is an anode plate (anode foil) made of aluminum material.

[0025] As a preferred embodiment of the present invention, the aluminum material may be AL1050, AL1100, AL1235, AL3003, AL3004, AL5005, AL8079, or AL8021.

[0026] As a preferred embodiment of the present invention, when a foreign substance remains in the anode current collector in which a spraying process using a CO2-containing mixed gas is performed, the foreign substance can satisfy a foreign substance size reduction rate of 5% or more according to Equation 1.

[0027] [Equation 1]

[0028] Foreign substance size reduction rate (%) = (AB) / A × 100%

[0029] In Equation 1, A is the maximum size (μm) of foreign matter present in the anode current collector before the foreign matter removal process, and B is the maximum size (μm) of foreign matter present in the anode current collector after the foreign matter removal process.

[0030] As a preferred embodiment of the present invention, an anode current collector in which a spraying process using a CO2-containing mixed gas is performed can satisfy a change rate in tensile strength according to Equation 2 of 1.00% or less.

[0031] [Equation 2]

[0032] Change in tensile strength (%) = │(CD) / C│×100%

[0033] In Equation 2, C is the tensile strength (N / mm²) of the anode current collector before the foreign substance removal process. 2 ) and D is the tensile strength (N / mm²) of the anode current collector after performing the material removal process. 2 ) and, at this time, the above tensile strength was measured using Daekyung Engineering's UTM equipment in accordance with ISO6892.

[0034] As a preferred embodiment of the present invention, an anode current collector in which a spraying process using a CO2-containing mixed gas is performed can satisfy a change rate of elongation rate according to Equation 3 of 2.50% or less.

[0035] [Equation 3]

[0036] Change in elongation rate (%) = │(EF) / E│×100%

[0037] In Equation 3, E is the elongation (%) of the anode current collector before the foreign substance removal process, and F is the elongation (%) of the anode current collector after the material removal process, wherein the elongation is measured using the UTM equipment of Daekyung Engineering Co., Ltd. in accordance with ISO 6892.

[0038] Another objective of the present invention is to provide an anode current collector from which foreign substances have been removed by the method described above. Effects of the invention

[0040] The method for removing foreign substances from the slitting cut portion of the positive current collector according to the present invention has very low or no change in the mechanical properties (tensile strength, elongation, etc.) of the positive current collector, and has excellent foreign substance removal effects such as burrs, and even if burrs remain, the size of the burrs is greatly reduced, so the defect rate as a positive current collector for secondary batteries can be greatly reduced, and the process time can be shortened compared to existing removal methods because the foreign substance removal method is efficient. Brief explanation of the drawing

[0042] Figure 1A is a schematic diagram of an air injector (supplyer) for CO2 gas and a carrier gas, and Figure 1B is a schematic diagram of a gas injection device of the type having four gas injection nozzles. Figure 2A is a schematic diagram showing gas injection devices installed on both sides of a roll on which an anode current collector is wound, and Figure 2B is a schematic diagram explaining the concept of injecting mixed gas from a gas injection nozzle on the side of the wound roll. Figures 3A and 3B are schematic diagrams showing gas injection devices installed on both cut sides of the positive current collector of a sheet or film, and Figure 3C is a schematic diagram explaining the concept of injecting mixed gas from a gas injection nozzle into the slitting cut side portion of the positive current collector. Figures 4 and 5 are optical microscope images of an anode current collector before (A) and after (B) treatment for removing foreign substances according to the present invention. Specific details for implementing the invention

[0043] The term "slitting cutting area" used in this invention refers to the slitting cutting surface of the anode current collector (anode plate, anode foil) and the upper and lower surfaces of the anode current collector near the slitting cutting surface.

[0044] The term "foreign substance" as used in this invention includes adhesive foreign substances and non-adhesive foreign substances, unless otherwise specifically stated.

[0046] The present invention will be described in more detail below.

[0047] In order to remove adhesive foreign substances such as burrs that are generated in large quantities during processing of the anode plate (anode foil), which is an anode current collector, such as slitting cutting, conventional methods were performed using wet processing with a cleaning solution or physical processing methods using dust-free cloth, OPP tape, etc. However, these conventional methods had the disadvantage that a large amount of residual adhesive foreign substances remained, and when foreign substances remained, the size of the residual adhesive foreign substances was large, and the processing time was long or additional subsequent processes such as drying had to be performed.

[0048] The present invention is an invention that improves upon existing foreign substance removal processes. It was discovered that when CO2 gas is used, burrs, which are adhesive foreign substances in the anode dust collector, are physically removed by collisions between gaseous CO2 particles and some solidified CO2 particles, and that the size of the burrs is reduced by thermal effects. The invention derives optimal conditions for removing foreign substances using CO2 gas.

[0049] The present invention provides a method for removing foreign substances from a slitting cut portion of an anode current collector by performing a process of spraying a CO2-containing mixed gas onto the slitting cut portion of the anode current collector to remove foreign substances from the slitting cut portion. At this time, the slitting cut portion refers to the longitudinal direction of the anode current collector.

[0050] In the present invention, the injection process is performed using a gas injection device equipped with a gas injection nozzle, which mixes CO2 gas supplied from a gas supply unit (see A in FIG. 1) with air, which is a carrier gas.

[0051] The above gas injection device (30) may be equipped with 3 to 5 gas injection nozzles (31), preferably 3 to 4. As a preferred embodiment, a gas injection device equipped with 4 gas injection nozzles such as B of FIG. 1 may be used.

[0052] The mixed gas injected through the above gas injection nozzle may contain 90.0 to 98.0 volume% of CO2 and the remaining amount of air, preferably 93.0 to 97.5 volume% of CO2 and the remaining amount of air, and more preferably 94.0 to 96.5 volume% of CO2 and the remaining amount of air. At this time, the volume% of CO2 in the mixed gas can be controlled by adjusting the supply rate of CO2 and / or air supplied by the gas supplier.

[0053] In addition, the mixed gas injected from the gas injection nozzle is heat-treated so that the mixed gas has a specific temperature before injection, and then injected from the gas injection nozzle. At this time, the temperature of the injected mixed gas is preferably 90 to 120°C, preferably 90 to 110°C, and more preferably 95 to 110°C. At this time, if the temperature of the mixed gas is less than 90°C, the effect of reducing the size of the burr may be insufficient, and if it exceeds 120°C, it is uneconomical.

[0054] In addition, the injection pressure of the mixed gas is preferably 6.0 to 10.0 bar, more preferably 6.0 to 8.5 bar, and more preferably 6.5 to 8.0 bar. At this time, if the injection pressure of the mixed gas is less than 6 bar, the effect of physically detaching foreign substances from the anode current collector and the thermal effect are insufficient, so the efficiency of removing foreign substances may decrease, and if the injection pressure of the mixed gas exceeds 10 bar, it is uneconomical because there is insufficient increase in the additional efficiency of removing foreign substances.

[0056] The gas injection method of the present invention is described as follows.

[0057] In the case where the slitting cut anode current collector is wound into a roll (roll, 10), the gas injection device (30) is installed so that gas injected from the gas injection nozzle (31) is injected in a vertical direction relative to the side of the roll, and the gas injection device may be installed on one side or both sides of the slitting cut surface (20) of the roll (see A in FIG. 3). Additionally, two or more gas injection devices may be installed on one side.

[0058] At this time, the vertical direction means that the angle formed by the side of the wound roll and the centerline of the gas injection nozzle is 0° to 15°, preferably 0° to 10°, and more preferably 0° to 7° (see Fig. 3B).

[0060] Additionally, when the slit-cut anode current collector is a sheet or film (12), the gas injection device (30) may be installed so that the gas injected from the gas injection nozzle (31) is injected in a horizontal direction relative to the slit-cut surface of the sheet or film (see FIG. 4A). And, the gas injection device may be installed on one or both sides of the slit-cut surface of the sheet or film (Fig. 4B).

[0061] In addition, the gas injection device installed on one or both sides may be installed on the upper and / or lower portions of each of the one or both sides.

[0062] At this time, the horizontal direction means that the angle formed by the centerline of the slitting cut surface (20) and the gas injection nozzle (31) is 0° to 15°, preferably 0° to 10°, and more preferably 0° to 7° (see C in FIG. 4).

[0063] In addition, if the above-mentioned slit-cut anode current collector is a sheet or a film, the process of spraying the CO2-containing mixed gas may be performed before rolling the cut anode current collector, or before reprocessing the rolled anode current collector.

[0065] The anode current collector described above is an anode plate (anode foil) made of aluminum.

[0066] In addition, the aluminum material may be AL1050, AL1100, AL1235, AL3003, AL3004, AL5005, AL8079, or AL8021, preferably AL1050, AL1100, AL1235, AL3003, or AL3004, and more preferably AL1100 or AL1235.

[0067] In the case where foreign substances remain in the anode current collector in which the injection process using a CO2-containing mixed gas is performed by the method described above, the remaining foreign substances can satisfy a foreign substance size reduction rate according to Equation 1 of 5% or more, preferably 5 to 90%, and more preferably 35.0 to 90.0%.

[0068] [Equation 1]

[0069] Foreign substance size reduction rate (%) = (AB) / A × 100%

[0070] In Equation 1, A is the maximum size (μm) of foreign matter present in the anode current collector before the foreign matter removal process, and B is the maximum size (μm) of foreign matter present in the anode current collector after the foreign matter removal process.

[0071] In addition, the anode current collector, through which a spraying process using a CO2-containing mixed gas is performed, can satisfy a change rate in tensile strength according to Equation 2 of 1.00% or less, preferably 0.80% or less, and more preferably 0.01 to 0.75%.

[0072] [Equation 2]

[0073] Change in tensile strength (%) = │(CD) / C│×100%

[0074] In Equation 2, C is the tensile strength (N / mm²) of the anode current collector before the foreign substance removal process. 2 ) and D is the tensile strength (N / mm²) of the anode current collector after performing the material removal process. 2) and, at this time, the above tensile strength was measured using Daekyung Engineering's UTM equipment.

[0075] In addition, the anode current collector in which the injection process using a CO2-containing mixed gas is performed can satisfy a change rate of elongation according to Equation 3 of 2.5% or less, preferably 0.05 to 2.40%, and more preferably 0.05 to 2.15%.

[0076] [Equation 3]

[0077] Change in elongation rate (%) = │(EF) / E│×100%

[0078] In Equation 3, E is the elongation (%) of the anode current collector before the foreign substance removal process, and F is the elongation (%) of the anode current collector after the substance removal process, wherein the elongation is measured using the UTM equipment of Daekyung Engineering.

[0080] As explained above, the method for removing foreign substances from the slitting cut portion of the positive current collector according to the present invention has very low or no change in the mechanical properties (tensile strength, elongation, etc.) of the positive current collector, and has excellent foreign substance removal effects such as burrs. Even if burrs remain, the size of the burrs is significantly reduced, so the defect rate as a positive current collector for secondary batteries can be significantly reduced, and the foreign substance removal method is efficient, so the process time can be shortened compared to existing removal methods.

[0081] The positive current collector from which foreign substances have been removed in this manner can be applied as a positive current collector for a secondary battery, thereby ensuring the stability of the secondary battery. Furthermore, the secondary battery may be a secondary battery applied to electronic devices, means of transportation, energy storage systems (ESS), etc.

[0083] The present invention will be explained in more detail below through examples. However, the following examples are intended to aid in understanding the present invention and should not be interpreted as limiting the scope of the present invention.

[0084] [Example]

[0085] Examples 1-1 to 1-3: Removal of foreign substances from slit-cut anode current collector

[0086] A roll wound with a slit-cut anode current collector was prepared. In this case, the material of the anode current collector is AL1100 aluminum.

[0087] A gas injection device is installed on both sides of the slitting cutting surface of the roll, such that the angle formed by the side of the roll and the centerline of the gas injection nozzle is 0° to 5°.

[0088] In addition, the gas injection device is a gas injection device equipped with four gas injection nozzles (see B in FIG. 1), and the mixed gas supplied to the gas injection device is a mixed gas comprising CO2 gas supplied from a gas supply unit (see A in FIG. 1) and air as a carrier gas. In addition, before the mixed gas is supplied to the gas injection device, the mixed gas to be supplied and injected is heat-treated to reach 100°C.

[0089] At this time, the CO2 supply pressure and air pressure supplied from the gas supplier were adjusted as shown in Table 1 below so that the mixed gas contained 94.5 volume% CO2 and the remaining air of 100 volume%.

[0090] Then, the mixed gas was sprayed onto the side of the roll (slitting cut surface) for about 8 minutes so that the injection pressure of the mixed gas from the gas injection device was 7.3 bar, thereby removing foreign substances.

[0091] Then, after preparing a roll different from the one on which the anode current collector was wound, foreign matter removal was performed under the same conditions to carry out Examples 1-1 to 1-3.

[0093] Examples 2-1 to 2-2 and Examples 3 to 4

[0094] After preparing a roll wound with a different anode current collector than the roll of Example 1, foreign matter removal was performed in the same manner as in Example 1, but Examples 2-1 to 2-2, Example 3, and Example 4 were carried out by varying the supply pressure of the air supplied from the supply device as shown in Table 1 below.

[0096] Experimental Example 1: Measurement of Burr Size Change 1

[0097] The size of the burrs fixed inside the anode current collector before and after the foreign substance removal treatment of Examples 1 to 3 was measured, and the change in burr size before and after the foreign substance removal treatment was measured, and the results are shown in Table 1 below. In addition, optical microscope measurement images of the change in burr size existing before and after the foreign substance removal treatment of the anode current collectors of Examples 1-1 to 1-3 are shown in Figures 4 and 5, and Figures 4 and 5 were measured using different optical microscope modes.

[0098] And, the above foreign substance size reduction rate was calculated based on the following Equation 1.

[0099] [Equation 1]

[0100] Foreign substance size reduction rate (%) = (AB) / A × 100%

[0101] In Equation 1, A is the maximum size (μm) of foreign matter present in the anode current collector before the foreign matter removal process, and B is the maximum size (μm) of foreign matter present in the anode current collector after the foreign matter removal process.

[0102] division Gas supply pressure Mixed gas injection temperature Mixed gas injection pressure Maximum burr size (㎛) before treatment Maximum burr size (㎛) after treatment Foreign substance size reduction rate (%) CO2(psi) air (bar) Example 1-1 100 0.4 100℃ 7.3 bar 35.63 8.1 77.27 Examples 1-2 50.8 5.1 89.96 Examples 1-3 23.3 10.9 53.22 Example 2-1 100 0.5 11.29 10.7 5.23 Example 2-2 11.36 7.2 36.62 Example 3 100 0.6 15.20 11.4 25.00 Example 4 105 0.4 14.07 8.4 40.30

[0103] Through the reduction rate of the burr size, which is a foreign substance, in Table 1 above, it was confirmed that the thermal effect of CO2 gas applied as the foreign substance removal method of the present invention has the effect of significantly reducing the size of the burr.

[0105] Experimental Example 3: Measurement of Tensile Strength and Elongation

[0106] The tensile strength and elongation of each anode current collector of Example 1-1, Example 2-2, and Example 3 before and after foreign substance removal treatment were measured in accordance with ISO 6892 using a UTM machine from Daekyung Engineering Co., Ltd. with a grip of 50 mm and a width of 12.8 mm, and the results are shown in Table 2 below.

[0107] In addition, the rate of change in tensile strength was calculated according to Equation 2 below, and the rate of change in elongation was calculated according to Equation 3 below.

[0108] [Equation 2]

[0109] Change in tensile strength (%) = │(CD) / C│×100%

[0110] In Equation 2, C is the tensile strength (N / mm²) of the anode current collector before the foreign substance removal process. 2 ) and D is the tensile strength (N / mm²) of the anode current collector after performing the material removal process. 2 )am.

[0111] [Equation 3]

[0112] Change in elongation rate (%) = │(EF) / E│×100%

[0113] In Equation 3, E is the elongation (%) of the anode current collector before the foreign substance removal process, and F is the elongation (%) of the anode current collector after the substance removal process.

[0114] division Tensile strength (N / mm²) 2 ) Tensile strength change rate (%) Elongation rate (%) Change in elongation rate (%) Before processing After processing Before processing After processing Example 1-1 272.53 270.53 0.73 3.79 3.87 2.11 Example 2-2 283.88 283.12 0.27 3.47 3.48 0.29 Example 3 275.18 275.08 0.04 3.51 3.52 0.28

[0115] Through the change rates of tensile strength and elongation in Table 2 above, it was confirmed that the rate of change in mechanical properties of the anode current collector from which foreign substances were removed by the foreign substance removal method of the present invention is very low.

[0117] Comparative Example 2 and Comparative Example 3

[0118] Under the same conditions as Example 1-1 above The removal of foreign substances from a roll wound with an anode current collector was performed, and as a gas injection device, Comparative Example 2 was carried out using a gas injection device equipped with one gas injection nozzle instead of a gas injection device equipped with four gas injection nozzles, and Comparative Example 3 was carried out using a gas injection device equipped with eight gas injection nozzles.

[0119] In addition, Comparative Example 2 was performed for a gas injection time of 20 minutes, and Comparative Example 3 was performed for 4 minutes. Then, the gas injection treatment time at which the foreign substance removal efficiency within the anode current collector of Example 1-1, Comparative Example 2, and Comparative Example 3 reached 95% or higher was measured, and the results are shown in Table 3 below. At this time, the foreign substance removal efficiency was calculated by measuring the size before and after treatment using the EPMS (Electrode Plate Measurement System) Burr meter from Z00TOS.

[0120] division Gas injection treatment time Example 1-1 8 minutes Comparative Example 2 20 minutes Comparative Example 3 4 minutes

[0121] Looking at the measurement results of foreign substance removal efficiency according to the number of gas injection nozzles in Table 3 above, in the case of Comparative Example 2, which has one gas injection nozzle, the foreign substance removal efficiency was relatively lower compared to Example 1-1, even though the processing time was very long.

[0122] In addition, Comparative Example 2, which has 8 gas injection nozzles, showed a result of insufficient improvement in foreign substance removal efficiency compared to Example 1-1.

[0124] Examples 6–7 and Comparative Examples 4–5

[0125] The removal of foreign substances from a roll wound with an anode current collector was performed under the same conditions as in Example 5 above, but the CO2 supply pressure of the gas supply pressure was adjusted to vary the CO2 content in the injected mixed gas as shown in Table 5 below, thereby removing foreign substances from the cut surface of the roll. The measurement results are shown in Table 4 below.

[0126] division Mixed gas injection direction CO2 volume percentage in mixed gas Maximum burr size (㎛) before treatment Maximum burr size (㎛) after treatment Foreign matter (bur) size reduction rate (%) Example 5 vertical direction 94.5 20.81 9.97 51.1% Example 6 90.4 17.26 11.19 35.0% Example 7 97.5 14.07 7.49 53.0% Comparative Example 4 88.3 23.55 22.77 3.3% Comparative Example 5 99.1 22.77 11.21 50.7%

[0127] Looking at the foreign substance size reduction rates in Table 4 above, Examples 5 to 7 showed results with a foreign substance size reduction rate of 35% or more.

[0128] In contrast, Comparative Example 4, in which the CO2 content in the mixed gas was less than 90 volume%, showed a result in a sharply lower reduction rate of foreign matter size compared to Example 6.

[0129] In addition, in the case of Comparative Example 5, in which the CO2 content in the mixed gas exceeded 98 volume%, there was a problem with damage to the cut surface compared to Example 7 (see Fig. 5).

[0132] Through the above examples and experimental examples, it was confirmed that the anode current collector from which foreign substances, such as fixed burrs, have been removed by the method presented by the present invention exhibits very low changes in mechanical properties, and even if burrs remain, the size of the burrs can be significantly reduced.

[0133] The positive current collector treated to remove foreign substances in this way is applied as a positive material for a secondary battery, which can reduce the defect rate and provide a secondary battery with excellent stability.

Claims

Claim 1 A method for removing foreign substances from a slitting cutting portion of an anode current collector, characterized by performing a spraying process in which a CO2-containing mixed gas is sprayed onto the slitting cutting portion of the anode current collector to remove foreign substances from the slitting cutting portion. Claim 2 A method for removing foreign substances from a slitting cut portion of an anode current collector according to claim 1, wherein the injection process is performed using a gas injection device equipped with a gas injection nozzle, and the gas injection device is characterized by having 3 to 5 gas injection nozzles. Claim 3 A method for removing foreign substances from a slitting cut portion of an anode current collector according to claim 2, wherein each of the 3 to 5 gas injection nozzles equipped in the gas injection device is equipped with a CO2 gas inlet and an air inlet, and a mixed gas formed by mixing these is injected through the gas injection nozzles. Claim 4 A method for removing foreign substances from a slitting cut portion of an anode current collector according to claim 1, characterized in that the mixed gas comprises 90.0 to 98.0 volume% of CO2 and the remaining amount of air. Claim 5 A method for removing foreign substances from a slitting cut portion of an anode current collector, characterized in that, in claim 1, the temperature of the mixed gas sprayed is 90 to 120℃. Claim 6 A method for removing foreign substances from a slitting cut portion of an anode current collector according to claim 1, wherein, when the slitting cut anode current collector is a wound roll, the gas injection device is installed such that the gas injected from the gas injection nozzle is injected in a vertical direction relative to the side of the roll, and the gas injection device is installed on one side or both sides of the slitting cut surface of the roll. Claim 7 A method for removing foreign substances from a slitting cut portion of an anode current collector according to claim 6, characterized in that the angle formed by the side of the wound roll and the centerline of the gas injection nozzle in the vertical direction is 0° to 15°. Claim 8 A method for removing foreign substances from the slitting cut portion of an anode current collector, characterized in that, in claim 6, the anode current collector is made of aluminum material such as AL1050, AL1100, AL1235, AL3003, AL3004, AL5005, AL8079, or AL8021. Claim 9 A method for removing foreign substances from a slitting cut portion of an anode current collector, wherein, in any one of claims 1 to 8, when a foreign substance remains in the anode current collector on which a spraying process using a CO2-containing mixed gas is performed, the remaining foreign substance satisfies a foreign substance size reduction rate of 5% or more according to Equation 1: [Equation 1] In Equation 1, the foreign substance size reduction rate (%) = (AB) / A × 100%, A is the maximum size (㎛) of the foreign substance present in the anode current collector before the foreign substance removal process, and B is the maximum size (㎛) of the foreign substance present in the anode current collector after the foreign substance removal process. Claim 10 A method for removing foreign substances from a slitting cut portion of an anode current collector, wherein, in any one of claims 1 to 8, the anode current collector on which a spraying process using a CO2-containing mixed gas is performed satisfies a change rate in tensile strength according to Equation 2 of 1.00% or less and a change rate in elongation according to Equation 3 of 2.5% or less: [Equation 2] Change rate of tensile strength (%) = │(CD) / C│×100% In Equation 2, C is the tensile strength of the anode current collector before the foreign substance removal process (N / mm² 2 ) and D is the tensile strength (N / mm²) of the anode current collector after performing the material removal process. 2 ) and, [Equation 3] Change in elongation rate (%) = │(EF) / E│×100% In Equation 3, E is the elongation (%) of the anode current collector before the foreign substance removal process, and F is the elongation (%) of the anode current collector after the material removal process; at this time, the tensile strength and elongation were measured using the UTM equipment of Daekyung Engineering Co., Ltd. in accordance with ISO 6892. Claim 11 A positive current collector for a secondary battery treated by the foreign substance removal method of claim 9.

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