Method and apparatus for activating a lithium secondary battery

Abstract

The activation method of the lithium secondary battery according to the present invention includes a pre-aging process in which an assembled lithium secondary battery is aged at room temperature, a formation process in which the lithium secondary battery is charged, and a roll-pressing process in which pressure is applied to the lithium secondary battery using a pressure roller, and the roll-pressing process applies pressure from the center of the lithium secondary battery toward the edge where the electrode lead is located. As a result, the sliding portion, which is relatively thin, can be pressed with a uniform force, preventing internal gas from being trapped and improving the performance of the battery.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0150389, filed on November 4, 2021.

[0002] The present invention relates to a method and an apparatus for activating a lithium secondary battery that prevents a local charging non-uniformity phenomenon.

Background Art

[0003] Generally, secondary batteries can be classified into cylindrical, prismatic, pouch-type, etc. according to their shapes. Among them, the pouch-type secondary battery uses a pouch exterior material composed of a multilayer film of a metal layer (foil) and synthetic resin layers coated on the upper and lower surfaces of the metal layer to form the appearance. Therefore, it can significantly reduce the weight of the battery compared to cylindrical or prismatic ones using metal cans, enabling weight reduction of the battery, and has the advantage of being able to change into various forms, so it has attracted much attention.

[0004] In such a pouch-type secondary battery, an electrode assembly is accommodated in a stacked form, and an electrode tab and an electrode lead are connected to the electrode assembly, and the electrode lead protrudes from the pouch exterior material. Such an electrode lead is electrically connected through contact with an external device and is supplied with power from the external device.

[0005] A pouch-type secondary battery is manufactured through a process of assembling cells and a process of activating the battery. In the battery activation stage, the secondary battery cells are mounted on a charge and discharge device, and charging and discharging are performed under the conditions necessary for activation. Thus, the process of performing predetermined charge and discharge using a charge and discharge device for battery activation is called a formation process.

[0006] FIGS. 1 and 2 illustrate an apparatus for a formation process. Referring to FIG. 1, the formation apparatus includes a frame 1, a pressing plate 2, and drive units 3: 3a, 3b. The drive unit 3 includes a drive shaft 3a and a drive motor 3b.

[0007] Inside the frame 1, a plurality of pressure plates 2 are arranged, and between the pressure plates 2, a secondary battery B for performing a formation process is arranged.

[0008] As shown in FIG. 1, when the drive shaft 3a rotates due to the rotation of the drive motor 3b and a plurality of pressure plates 2 engaged therewith move in one direction, as shown in FIG. 2, the pressure plates 2 press both sides of the secondary battery B. Such a pressure plate 2 is formed of a sturdy material such as aluminum.

[0009] On the other hand, the electrode assembly housed inside the secondary battery for performing the formation process has a structure in which a positive electrode / separator / negative electrode are laminated. Such a positive electrode and negative electrode are manufactured by applying an electrode slurry on an electrode current collector and drying and rolling. Since such an electrode slurry is applied in a fluid state, due to the characteristics of the fluid, the electrode slurry coating portion flows down, and the ends of the electrodes have an inclined form, which is referred to as a sliding portion.

[0010] FIG. 3 is a drawing illustrating problems that occur when a battery is pressed by a pressure plate included in the formation apparatus of FIGS. 1 to 2. Referring to FIG. 3, a negative electrode 10 having negative electrode active material layers 12 laminated on both sides of a negative electrode current collector 11, a positive electrode 20 having positive electrode active material layers 22 laminated on both sides of a positive electrode current collector 21, and a separator 30 interposed between the negative electrode 10 and the positive electrode 20 A pair of opposing pressure plates 2 press both sides of the laminated secondary battery B. The positive electrode active material layer 22 and the negative electrode active material layer 12 each include a sliding portion S having an inclined form at its end.

[0011] Since the electrode slurry is a fluid, the end of the electrode coating portion coated with the electrode slurry may include a sliding portion S that flows down onto the current collector and is inclined with respect to the plane of the current collector. Since the thickness of the electrode active material layer in such a sliding portion S is relatively thin compared to the thickness of the electrode active material layer in the flat portion, it is difficult to press the sliding portion S with the flat pressing plate 2, and thus a gas trap phenomenon may occur in which the gas generated during charging is confined in the space between the sliding portion S and the separator 30. And the gas trapped in this way is in the form of bubbles, which restricts the impregnation of the electrolyte and hinders the movement of lithium ions, which may deteriorate the quality of the battery, such as local charging non-uniformity and lithium precipitation.

[0012] Therefore, the actual situation is that there is a need for technological development of an activation method and an activation device that can solve such problems.

Summary of the Invention

Problems to be Solved by the Invention

[0013] The present invention is for solving the problems of the above-mentioned prior art, and aims to provide an activation method and an activation device for a secondary battery that prevent gas trapping in the electrode sliding portion and reduce risks such as local charging non-uniformity and lithium precipitation.

Means for Solving the Problems

[0014] An activation method for a lithium secondary battery according to an embodiment of the present invention includes a pre-aging process of aging the assembled lithium secondary battery at room temperature, a formation process of charging the lithium secondary battery, and a roll-pressing process of pressing the lithium secondary battery using a pressure roller. In the roll-pressing process, the pressure is applied from the central portion of the lithium secondary battery toward the edge where the electrode lead is located.

[0015] In the activation method according to an embodiment of the present invention, the roll pressing process may be performed before the formation process.

[0016] In the activation method according to an embodiment of the present invention, the roll pressing process may be performed during the formation process.

[0017] In the activation method according to an embodiment of the present invention, the roll pressing process may be performed before and during the formation process, respectively.

[0018] In the activation method according to an embodiment of the present invention, the roll pressing process may be performed 2 to 5 times.

[0019] In the activation method according to an embodiment of the present invention, the roll pressing process may press the lithium secondary battery at a linear pressure of 20 kgf / cm to 60 kgf / cm.

[0020] In the activation method according to an embodiment of the present invention, the pressing roller is composed of an upper pressing roller and a lower pressing roller, and the lithium secondary battery can be pressed while passing between the upper pressing roller and the lower pressing roller.

[0021] In the activation method according to an embodiment of the present invention, the formation process may include a process of applying a surface pressure to the lithium secondary battery during charging.

[0022] In the activation method according to an embodiment of the present invention, the formation process may be composed of a plurality of formation stages set so that the end-of-charge SOC is different, and each formation stage may be set so that one or more conditions selected from each charging rate and the surface pressure applied to the secondary battery are different.

[0023] In the activation method according to an embodiment of the present invention, it may further include an aging process of aging the battery after the formation process is completed.

[0024] The activation device for a lithium secondary battery according to the present invention includes a formation unit configured to apply pressure while charging and discharging the battery, an upper pressure roller, and a lower pressure roller, and a roll-pressing unit configured to apply pressure with the battery interposed between the upper pressure roller and the lower pressure roller.

[0025] In one embodiment of the present invention, a transfer unit for taking out and carrying in / out the battery is further included between the formation unit and the roll-pressing unit. The transfer unit may include a pickup unit for carrying out or carrying in the battery housed in the formation unit or the roll-pressing unit, a driving unit for moving the pickup unit, and a control unit for controlling the operations of the pickup unit and the driving unit.

[0026] In one embodiment of the present invention, the roll-pressing unit may include an upper pressure roller and a lower pressure roller, a driving unit for driving the upper pressure roller and the lower pressure roller to rotate, and a pressure cylinder for moving the upper pressure roller in the direction of the lower pressure roller or in the reverse direction.

[0027] In one embodiment of the present invention, the formation unit may include a frame for housing a plurality of battery cells, a charge / discharge unit for connecting to the electrode leads of the battery and charging and discharging the battery, a plurality of pressure plates for applying pressure to both sides of the battery, and a driving unit for moving the plurality of pressure plates.

Effects of the Invention

[0028] The activation method and activation device according to the present invention have the effect of preventing gas from being trapped in the sliding part because, by applying pressure by roll-pressing, the relatively thin sliding part is also pressed with the same force as the flat part of the electrode.

Brief Description of the Drawings

[0029]

Figure 1

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Figure 14

Explanation of reference numerals

[0030] 1: Frame 2: Pressure plate 3: Driving part 3a: Drive shaft 3b: Drive motor B: Secondary battery 10: Negative electrode 11: Negative electrode current collector 12: Negative electrode active material layer 20: Positive electrode 21: Positive electrode current collector 22: Positive electrode active material layer 30: Separator S: Sliding part 121, 122: Pressing rollers

Best Mode for Carrying Out the Invention

[0031] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Before that, the terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings, but should be construed as meanings and concepts consistent with the technical idea of the present invention based on the principle that the inventor can appropriately define the concept of the terms in order to explain his own invention in the best way.

[0032] Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. It should be understood that there may be various equivalents and modifications that can replace them at the time of this application.

[0033] Hereinafter, the present invention will be described in more detail.

[0034] (Method for Activating a Secondary Battery According to the First Embodiment) A method for activating a lithium secondary battery according to an embodiment of the present invention includes a pre-aging process of aging the assembled lithium secondary battery at room temperature, a formation process of charging the lithium secondary battery, and a roll pressing process of pressing the lithium secondary battery using a pressing roller. The roll pressing process is characterized by pressing from the central part of the lithium secondary battery toward the edge where the electrode lead is located.

[0035] FIG. 4 is a schematic diagram showing the roll pressing process of the present invention, and FIG. 5 is a conceptual diagram for explaining the effect of the roll pressing process according to an embodiment of the present invention. Referring to these drawings, in the roll pressing process of the present invention, the pressure roller includes an upper pressure roller 121 and a lower pressure roller 122, and the lithium secondary battery B is interposed between the upper pressure roller 121 and the lower pressure roller 122 facing each other, and is pressed by the rolling of the roller.

[0036] The pressing by such rollers 121 and 122 applies pressure to the secondary battery B in the form of line pressure, and the paired upper pressure roller 121 and lower pressure roller 122 rotate and travel from the center of the secondary battery B toward the edge direction where the electrode leads 13 and 23 are located, and sequentially press from the central part of the battery to the edge where the electrode leads are located.

[0037] Due to such sequential pressing, the internal gas moves from the central part of the battery to the edge region directionally. In addition, since the pressing surface of the roller is not flat but curved in the roller pressing, the sliding part S, which is relatively thinner compared to the central part of the battery, can also be pressed with the same load as the central part of the battery, thereby preventing gas from being trapped in this part, and thereby preventing local undercharging and lithium precipitation in the sliding part S.

[0038] Thus, the activation method according to the present invention includes a roll pressing process of applying line pressure to the battery. In the roll pressing process, the pressure roller rolls from the central part of the battery toward the edge of the battery where the sliding part S is located, so that the gas inside the electrode assembly can be discharged to the outside of the electrode assembly, and the relatively thin sliding part S can be pressed, thereby preventing gas from being trapped in the sliding part.

[0039] The pre-aging process is a process of aging the battery so that the electrolyte is sufficiently impregnated into the electrode assembly after the battery is assembled. When the assembly of the secondary battery is completed, the pre-aging process can be carried out by leaving the secondary battery injected with the electrolyte at room temperature for a certain period of time to stabilize it so that the electrolyte injected into the secondary battery is sufficiently wetted inside the electrode assembly.

[0040] More specifically, when the secondary battery is charged and electrons move on the conducting wire to the negative electrode to be charged, lithium ions are occluded in the negative electrode to achieve charge neutrality. At this time, lithium ions can be occluded at the site impregnated with the electrolyte, that is, the site where the ion migration path is maintained (wetting area), but it is relatively difficult to occlude at the non-wetting area of the electrolyte. Therefore, through the pre-aging process, the battery can be aged in an environment with certain humidity and temperature conditions so that the electrolyte can penetrate well into the positive and negative electrodes.

[0041] In one specific example, the required time for the pre-aging process can specifically be 3 hours to 72 hours, 6 hours to 60 hours, or 12 hours to 48 hours, and this can be suitably adjusted according to the materials of the positive electrode, negative electrode, and electrolyte, the design capacity of the secondary battery, etc.

[0042] Also, the temperature during pre-aging can be carried out under normal temperature conditions of 18°C to 28°C, specifically 19°C to 27°C, more specifically 20°C to 26°C, and even more specifically 21°C to 25°C, and it is not necessarily limited to this and can be suitably changed according to the characteristics of the battery to be designed.

[0043] The above formation process is a stage of charging a secondary battery to form a SEI (Solid Electrolyte Interface, hereinafter referred to as "SEI") film layer on the negative electrode, and is a process of charging an assembled secondary battery to a SOC level within a predetermined range of full charge capacity (SOC100%, SOC; State Of Charge). Here, the SOC within the above predetermined range can be SOC20% - 80%, and preferably can be SOC40% - 70%.

[0044] When a lithium secondary battery undergoes the formation process, lithium ions derived from lithium transition metal oxides such as the positive electrode active material and positive electrode additives contained in the positive electrode move to the carbon electrode of the negative electrode. Since these lithium ions are highly reactive, they react with the carbon negative electrode to generate compounds such as Li2CO3, LiO, and LiOH, and an SEI film is formed on the surface of the negative electrode by such compounds. The SEI film is a non-conductor formed when the ion movement amount of the battery increases. When the SEI film is formed, it prevents lithium ions from reacting with other substances at the negative electrode during subsequent charging of the secondary battery, and functions as a kind of ion tunnel to allow only lithium ions to pass through. When such an SEI film is formed, since lithium ions do not react with the negative electrode or other substances, the amount of lithium ions is maintained reversibly, and the charge and discharge of the secondary battery are maintained reversibly, so the life of the secondary battery can be improved. And it is not easily disintegrated even when left at high temperature or when charge and discharge are repeated, so there will be little change in the thickness of the battery.

[0045] The charging conditions of such a formation process can be charged according to conditions known in the art. Specifically, the charging method can be to charge in a constant current mode until the charging termination voltage is reached. At this time, the charging rate (c-rate) can be 0.01C - 2C, can be 0.1C - 1.5C, can be 0.2C - 1C, but is not necessarily limited to this, and can be suitably changed according to the characteristics of the positive and negative electrode materials.

[0046] In addition, the temperature condition in the initial charging process can be implemented at 18°C to 28°C, specifically 19°C to 27°C, and more specifically 20°C to 26°C.

[0047] In one specific example, the formation process may include a process of applying surface pressure to a lithium secondary battery during charging. When surface pressure is applied to the lithium secondary battery in the formation process, excessive volume expansion of the electrode due to charge and discharge can be prevented, the chemical reaction of the battery can be promoted to induce gas generation, and the generated gas can be moved to the gas pocket part.

[0048] In order to apply surface pressure to a lithium secondary battery during charging, the formation process according to an embodiment of the present invention can perform the formation process while being mounted on a jig formation device capable of pressurizing the lithium secondary battery, which is referred to as a jig formation process. Referring to FIGS. 1 and 2, the formation device used for formation includes a frame 1, a pressure plate 2, and drive parts 3: 3a, 3b. The drive part 3 includes a drive shaft 3a and a drive motor 3b.

[0049] A plurality of pressure plates 2 are arranged inside the frame 1, and a secondary battery B for performing the formation process is arranged between the pressure plates 2.

[0050] As shown in FIG. 1, when the drive shaft 3a rotates while the drive motor 3b rotates and a plurality of pressure plates 2 engaged therewith move in one direction, as shown in FIG. 2, the pressure plates 2 pressurize both sides of the secondary battery B. In this way, the formation device is configured to pressurize the battery with a lithium secondary battery interposed between a pair of pressure plates.

[0051] As described above, such a pressure plate is formed of a robust material, has a plate shape, and the surface for pressing the battery is flat. Therefore, in a region of the sliding part where the thickness of the battery to be pressed is relatively thin, it cannot be pressed. Thus, in a conventional formation device, as a result of the region of the sliding part with a relatively small thickness not being pressed, there has been a problem that internal gas is trapped in this part. However, since the activation method of the present invention includes a roll pressing process of pressing the battery with a pressure roller, the sliding part can be pressed, and it is possible to prevent the risk of local non-charging and lithium precipitation due to gas in the sliding part.

[0052] In one embodiment of the present invention, the surface pressure applied during the above formation process is 0.1 kgf / cm 2 ~7.5 kgf / cm 2 , preferably 0.2 kgf / cm 2 ~7.0 kgf / cm 2 , more preferably 0.3 kgf / cm 2 ~6.5 kgf / cm 2 and can be set in the range.

[0053] In the activation method according to one embodiment of the present invention, the above formation process may be composed of a plurality of formation processes set so that the end-of-charge SOC is different. For example, the formation process according to the present invention includes a first formation stage of charging a secondary battery to less than SOC 10%, a second formation stage of charging the lithium secondary battery that has undergone the first formation stage to a charge depth set in the range of SOC 10% to 30%, a third formation stage of charging the lithium secondary battery that has undergone the second formation stage to a charge depth set in the range of SOC 35% to 50%, and a fourth formation stage of charging the lithium secondary battery that has undergone the third formation stage to a charge depth set in the range of more than SOC 50% and 70%. In the above example, an embodiment in which the formation process consists of four stages has been described, but it is not limited thereto, and the formation process may consist of two to five stages.

[0054] Also, the plurality of formation steps can be set such that at least one selected from the charging rate and the surface pressure applied to the secondary battery is different for each step.

[0055] Specifically, at the initial stage of the formation process, the battery can be pressurized with a weak surface pressure, and after the initial formation process, the battery can be pressurized with a stronger surface pressure.

[0056] At this time, the initial stage of the formation process can be a state in which the state of charge (SOC) of the secondary battery is charged to 3% to 30%.

[0057] Specifically, in the initial formation process, the pressure can be applied at a surface pressure of 0.1 kgf / cm 2 ~1.0 kgf / cm 2 , preferably 0.2 kgf / cm 2 ~0.8 kgf / cm 2 , more preferably 0.3 kgf / cm 2 ~0.7 kgf / cm 2 . In the subsequent formation process, the pressure can be applied at a surface pressure of 2.5 kgf / cm 2 ~7.5 kgf / cm 2 , preferably 3.0 kgf / cm 2 ~7.0 kgf / cm 2 , more preferably 3.5 kgf / cm 2 ~6.5 kgf / cm 2 .

[0058] Thus, when increasing the pressure applied to the battery as the state of charge increases during the formation process, by applying a low surface pressure in the initial formation process where the amount of gas generation is small, the electrolyte can be sufficiently impregnated into the electrode assembly in the lithium secondary battery. In the middle / late formation process where a large amount of internal gas is generated, a high surface pressure can be applied to remove the internal gas. As a result, an appropriate amount of electrolyte can be impregnated into the electrode assembly, and at the same time, there is an effect that the internal gas can be efficiently removed.

[0059] Also, during the initial formation process, slow charging at 0.01C to 0.5C can be carried out, and during the mid / late formation process, charging can be carried out at a charging rate of 0.6C to 1.5C. During the initial formation process, the electrolyte may not be sufficiently impregnated into the electrodes, so slow charging can reduce the risk of non-charging.

[0060] In this specification, the above roll pressing process is described as one roll pressing process by combining the process of rolling a pair of pressure rollers from the central part of the battery toward one side edge and the process of rolling from the central part of the battery toward the other side edge.

[0061] Such a roll pressing process can be performed once, or can be performed 2 to 5 times. The number of pressurizations can be appropriately adjusted according to the thickness of the battery and the degree of sliding in the sliding part.

[0062] In one specific example, the above roll pressing process can be to pressurize the battery with a linear pressure of 20 kgf / cm to 60 kgf / cm, preferably 25 kgf / cm to 50 kgf / cm.

[0063] FIG. 6 is a flowchart of a method for activating a lithium secondary battery according to a first embodiment of the present invention. Referring to FIG. 6, the activation method according to the first embodiment can sequentially perform a pre-aging process of aging the assembled lithium secondary battery at room temperature - a roll pressing process of pressurizing the secondary battery using a pressure roller - a formation process of charging the lithium secondary battery. That is, the method for activating the secondary battery according to the first embodiment is to perform the above roll pressing process before the formation process.

[0064] Even before the formation process, bubbles can be generated during the electrolyte injection process, and a small amount of gas can be generated as the electrolyte is impregnated into the electrodes during the pre-aging process. Therefore, by performing a roll pressing process before the formation process, such bubbles and gas can be discharged to the outside of the electrode assembly.

[0065] Figure 7 is a flowchart of a method for activating a lithium secondary battery according to an embodiment of the present invention. Referring to Figure 7, the activation method according to an embodiment of the present invention includes a pre-aging process of aging the assembled lithium secondary battery at room temperature, a roll pressing process of pressing the secondary battery using a pressure roller, a formation process of charging the lithium secondary battery, and an aging process of aging the formed lithium secondary battery.

[0066] The above aging process is a process of aging the secondary battery under various conditions in order to accelerate the stabilization of the SEI film formed through the above formation process.

[0067] The above aging process can go through a normal temperature aging process of aging the secondary battery for a predetermined time under normal temperature / normal pressure conditions. Depending on the purpose, high temperature aging can also be implemented instead of normal temperature aging, and both normal temperature aging and high temperature aging can be implemented.

[0068] The above high temperature aging is to age the battery in a high temperature environment, which can accelerate the stabilization of the SEI film, and the high temperature aging and normal temperature aging processes can be sequentially implemented for the initially charged battery.

[0069] In one specific example, the above high temperature aging can be implemented at a temperature of 50°C to 100°C, preferably 50°C to 80°C. The above high temperature aging can be performed for 1 hour to 30 hours, preferably 2 hours to 24 hours.

[0070] In one specific example, the above normal temperature aging can be carried out at a temperature of 18°C to 28°C, specifically 19°C to 27°C, more specifically 20°C to 26°C, and even more specifically 21°C to 25°C. The normal temperature aging can be carried out for 12 hours to 120 hours, or 18 hours to 72 hours.

[0071] In addition, the activation method according to an embodiment of the present invention may further include a degassing process of discharging the gas collected inside the secondary battery to the outside. The degassing process is a process of discharging the gas inside the secondary battery to the outside, and the gas collected inside the battery case or the gas pocket part is discharged to the outside of the battery by the roll pressing process.

[0072] For such a degassing process, various degassing technologies known at the time of filing the present application can be adopted. For example, in a pouch-type secondary battery in which one side is extended and formed, the extended part can be cut open, and the degassing process can be performed on the cut part by a sealing method. However, since such degassing technologies are widely known to those skilled in the art, a more detailed description will be omitted.

[0073] In addition, the activation method according to an embodiment of the present invention may further perform a full discharge and full charge process of fully discharging the secondary battery to near 0% SOC and then charging it to 95% or more of the designed capacity of the discharged secondary battery (SOC95%). The above full discharge and full charge process can be performed once or repeated two or more times.

[0074] In one specific example, the activation method of the secondary battery according to the present invention may further perform an additional aging process after the above full discharge and full charge processes. The additional aging process is a process of stabilizing the secondary battery, which can be carried out at normal temperature or high temperature, and specifically can be carried out for 1 day to 21 days. The above additional aging process may include a monitoring (OCV tracking) process of measuring the open circuit voltage (OCV) of the battery at regular time intervals in order to select low voltage defective batteries in which the voltage drops beyond the self-discharge of the battery.

[0075] (Method for Activating a Secondary Battery According to the Second Embodiment) In the method for activating a secondary battery according to the second embodiment, the roll pressing process can be performed during the formation process.

[0076] FIG. 8 is a flowchart of a method for activating a lithium secondary battery according to the second embodiment of the present invention. Referring to FIG. 8, the activation method according to the second embodiment includes a pre-aging process of aging the assembled lithium secondary battery at room temperature - a first formation stage of charging the lithium secondary battery - a roll pressing process of pressing the secondary battery using a pressure roller - a second formation stage of charging the lithium secondary battery, which can be sequentially performed.

[0077] In the formation process, when a large amount of gas is generated due to a full-scale chemical reaction between the electrode and the electrolyte by charging the secondary battery, the method for activating a secondary battery according to the second embodiment performs a roll pressing process during the formation process, so that there is an effect of effectively preventing the gas generated in the formation process from being trapped in the electrode assembly.

[0078] The activation method according to the second embodiment is such that the formation process is composed of a plurality of formation stages set with different end-of-charge SOCs, and the roll pressing process can be performed between the formation stages.

[0079] For example, the formation process can consist of a first formation stage where the end-of-charge SOC is set in the range of 10% to 40% and a second formation stage where the end-of-charge SOC is set in the range of 45% to 60%, and the roll pressing process can be performed between the first formation stage and the second formation stage.

[0080] When performing the formation process with the battery mounted on the formation device shown in FIGS. 1 and 2 that can pressurize the battery, after completing the first formation stage, the battery is taken out from the formation device, the roll pressing process is performed, and when the roll pressing process is completed, the battery is mounted on the formation device again, and the second formation stage can be performed.

[0081] After the formation process is completed in this way, the aging process described above can be performed.

[0082] The activation method according to the second embodiment is different from the activation method according to the first embodiment only in that the roll pressing process is performed during the formation. Since the specific contents of the pre-aging process, the roll pressing process, and the formation process are as described above, a detailed description thereof will be omitted.

[0083] Also, in the activation method according to another embodiment of the present invention, the roll pressing process can also be performed before and during the formation process. Referring to FIG. 14, the activation method according to another embodiment of the present invention can sequentially perform a pre-aging process, a roll pressing process - a first formation stage, a roll pressing process, and a second formation stage.

[0084] Hereinafter, the lithium secondary battery manufactured according to the activation method of the present invention will be described in detail.

[0085] The lithium secondary battery of the present invention is manufactured by accommodating an electrode assembly having a structure of a positive electrode / separator / negative electrode in a battery case, injecting an electrolyte, and sealing it.

[0086] Specifically, after manufacturing the positive electrode and the negative electrode by applying an electrode mixture containing an electrode active material and a binder to an electrode current collector, an electrode assembly is prepared with a separator interposed between the positive electrode and the negative electrode.

[0087] After accommodating the thus-prepared electrode assembly in a battery case, an electrolyte is injected, and the battery case is sealed to assemble the battery.

[0088] The step of assembling such a battery is not particularly limited and can be carried out according to known methods.

[0089] Further, the above electrode assembly is not particularly limited as long as it has a structure including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and can be, for example, a jelly roll type, a stack type, or a stack / folding type.

[0090] The above battery case is not particularly limited as long as it is used as an exterior material for packaging the battery, and a cylindrical shape, a rectangular shape, or a pouch type can be used.

[0091] When the above battery case is of a pouch type, an aluminum laminated pouch including an aluminum layer can be used. After injecting the above electrolyte, the opened portion of the aluminum laminated pouch can be sealed by heat welding or heat fusion.

[0092] The lithium secondary battery of the present invention includes a positive electrode, a negative electrode, an electrode assembly including a separator disposed between the positive electrode and the negative electrode, and an electrolyte.

[0093] The above positive electrode includes a positive electrode current collector and a positive electrode active material layer manufactured by applying, drying, and pressing a positive electrode mixture slurry on the above positive electrode current collector. The positive electrode mixture includes a positive electrode active material and a binder, and may further include a positive electrode additive, a conductive material, and a filler as necessary.

[0094] The above-mentioned positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically, may include a lithium composite metal oxide containing one or more metals such as cobalt, manganese, nickel, or aluminum and lithium. More specifically, the above-mentioned lithium composite metal oxide is a lithium-manganese-based oxide (for example, LiMnO2, LiMn2O4, etc.), a lithium-cobalt-based oxide (for example, LiCoO2, etc.), a lithium-nickel-based oxide (for example, LiNiO2, etc.), a lithium-nickel-manganese-based oxide (for example, LiNi 1-Y Mn Y O2 (where 0 < Y < 1), LiMn 2-Z Ni Z O4 (where 0 < Z < 2), etc.), a lithium-nickel-cobalt-based oxide (for example, LiNi 1-Y1 Co Y1 O2 (where 0 < Y1 < 1), etc.), a lithium-manganese-cobalt-based oxide (for example, LiCo 1-Y2 Mn Y2 O2 (where 0 < Y2 < 1), LiMn 2-Z1 Co Z1 O4 (where 0 < Z1 < 2), etc.), a lithium-nickel-manganese-cobalt-based oxide (for example, Li(Ni p Co q Mn r1 )O2 (where 0 < p < 1, 0 < q < 1, 0 < r1 < 1, p + q + r1 = 1) or Li(Ni p1 Co q1 Mn r2 )O4 (where 0 < p1 < 2, 0 < q1 < 2, 0 < r2 < 2, p1 + q1 + r2 = 2), etc.), or a lithium-nickel-cobalt-transition metal (M) oxide (for example, Li(Ni p2 Co q2 Mn r3 M s2)O2) (where M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, and p2, q2, r3, and s2 are atomic fractions of independent elements, 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, and p2 + q2 + r3 + s2 = 1), etc.) can be mentioned, and any one or two or more of these compounds may be included. Among them, in terms of enhancing the capacity characteristics and stability of the battery, the above lithium composite metal oxide is LiCoO2, LiMnO2, LiNiO2, lithium nickel manganese cobalt oxide (for example, Li(Ni 0.6 Mn 0.2 Co 0.2 )O2), Li(Ni 0.5 Mn 0.3 Co 0.2 )O2, or Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, etc.), or lithium nickel cobalt aluminum oxide (for example, Li(Ni 0.8 Co 0.15 Al 0.05 )O2, etc.), etc. can be used. Considering the remarkable improvement effect by controlling the types and content ratios of the constituent elements forming the lithium composite metal oxide, the above lithium composite metal oxide can be Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni 0.5 Mn 0.3 Co 0.2 )O2, Li(Ni 0.7 Mn 0.15 Co 0.15 )O2, or Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, etc., and any one or two or more of these mixtures can be used.

[0095] Also, the content of the above positive electrode active material can be 85 to 99 parts by weight, specifically 88 to 98 parts by weight, 90 to 97 parts by weight, or 92 to 95 parts by weight with respect to 100 parts by weight of the positive electrode binder.

[0096] The above conductive material can be used to improve the performance such as the electrical conductivity of the positive electrode, and one or more selected from the group consisting of natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, and carbon fiber can be used. For example, the above conductive material may contain acetylene black.

[0097] Also, the above conductive material can be included in an amount of 1 to 10 parts by weight, specifically 2 to 8 parts by weight, or 2 to 6 parts by weight, based on 100 parts by weight of the composite layer.

[0098] Also, the above binder may contain one or more resins selected from the group consisting of polyvinylidene fluoride - hexafluoropropylene copolymer (PVDF - co - HFP), polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, and copolymers thereof. As an example, the above binder may contain polyvinylidene fluoride.

[0099] Also, the above binder can be included in an amount of 1 to 10 parts by weight, specifically 1 to 8 parts by weight, or 1 to 6 parts by weight, based on 100 parts by weight of the entire composite.

[0100] Also, the average thickness of the above composite layer is not particularly limited, but specifically can be 50 μm to 300 μm, more specifically 100 μm to 200 μm, 80 μm to 150 μm, 120 μm to 170 μm, 150 μm to 300 μm, 200 μm to 300 μm, or 150 μm to 190 μm.

[0101] In addition, as the current collector of the positive electrode, one having high conductivity without inducing chemical changes in the battery can be used. For example, stainless steel, aluminum, nickel, titanium, fired carbon, etc. can be used, and in the case of aluminum or stainless steel, those surface-treated with carbon, nickel, titanium, silver, etc. can also be used. Further, the current collector can also form fine irregularities on the surface to enhance the adhesive force of the positive electrode active material, and various forms such as films, sheets, foils, nets, porous bodies, foams, non-woven fabrics, etc. are possible. Further, the average thickness of the current collector can be preferably applied in the range of 3 to 500 μm in consideration of the conductivity and total thickness of the positive electrode to be manufactured.

[0102] In addition, the negative electrode of the lithium secondary battery used in the present invention is manufactured by applying, drying, and pressing a negative electrode active material on a negative electrode current collector, and if necessary, a conductive material, an organic binder polymer, an additive, etc. similar to the positive electrode can be selectively further included.

[0103] In addition, the negative electrode active material is, for example, graphite having a completely formed layered crystal structure like natural graphite, soft carbon having a low-crystalline layered crystal structure (graphene structure; a structure in which hexagonal honeycomb planes of carbon are arranged in layers), and hard carbon in which these structures are mixed with an amorphous part, artificial graphite, expanded graphite, carbon fiber, difficult graphitization carbon, carbon black, carbon nanotube, fullerene, activated carbon, etc. carbon and graphite materials, Li x Fe2O3(0≦x≦1), Li x WO2(0≦x≦1), Sn x Me 1-x Me' y O z(Me: Mn, Fe, Pb, Ge, Me', Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogens, 0 < x ≤ 1, 1 ≤ y ≤ 3, 1 ≤ z ≤ 8), etc. metal composite oxides, lithium metal, lithium alloys, silicon-based alloys, tin-based alloys, SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, and Bi2O5, etc. metal oxides, conductive polymers such as polyacetylene, Li-Co-Ni-based materials, titanium oxide, lithium titanate, etc. can be used.

[0104] As an example, the negative electrode active material may contain both graphite and silicon (Si)-containing particles. The graphite may include one or more of natural graphite having a layered crystal structure and artificial graphite having an isometric structure. The silicon (Si)-containing particles are particles containing silicon (Si) as a main component as a metal component, and may include silicon (Si) particles, SiO particles, SiO2 particles, or a mixture of one or more of these particles.

[0105] In this case, the negative electrode active material may contain 80 to 95 parts by weight of graphite and 1 to 20 parts by weight of silicon (Si)-containing particles with respect to 100 parts by weight in total. By adjusting the content of graphite and silicon (Si)-containing particles contained in the negative electrode active material within the above range, the present invention can improve the charge capacity per unit mass while reducing the lithium consumption amount and the loss of irreversible capacity during the initial charge and discharge of the battery.

[0106] Also, the negative electrode binder layer may have an average thickness of 100 μm to 200 μm. Specifically, it may have an average thickness of 100 μm to 180 μm, 100 μm to 150 μm, 120 μm to 200 μm, 140 μm to 200 μm, or 140 μm to 160 μm.

[0107] In addition, the negative electrode current collector is not particularly limited as long as it has high conductivity without inducing chemical changes in the battery. For example, copper, stainless steel, nickel, titanium, fired carbon, etc. can be used. In the case of copper or stainless steel, those surface-treated with carbon, nickel, titanium, silver, etc. can also be used. Similar to the positive electrode current collector, the negative electrode current collector can also have fine irregularities formed on its surface to strengthen the bonding force with the negative electrode active material, and various forms such as films, sheets, foils, nets, porous bodies, foams, non-woven fabric bodies, etc. are possible. Also, the average thickness of the negative electrode current collector can be preferably applied in the range of 3 to 500 μm in consideration of the conductivity and total thickness of the manufactured negative electrode.

[0108] In addition, the separator is interposed between the positive electrode and the negative electrode, and an insulating thin film having high ion permeability and mechanical strength is used. The separator is not particularly limited as long as it is commonly used in the art. Specifically, sheets or non-woven fabrics made of chemical-resistant and hydrophobic polypropylene, glass fiber, or polyethylene, etc. can be used. In some cases, a composite separator in which inorganic particles / organic particles are coated on a porous polymer substrate such as the above sheet or non-woven fabric with an organic binder polymer can also be used. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte can also serve as the separator. Also, the pore diameter of the separator is on average 0.01 to 10 μm, and the thickness can be on average 5 to 300 μm.

[0109] The electrolyte may contain an organic solvent, a lithium salt, and an additive.

[0110] The organic solvent is not limited as long as decomposition due to oxidation reaction or the like can be minimized during the charge and discharge process of the battery. For example, it can be a cyclic carbonate, a linear carbonate, an ester, an ether, or a ketone, etc. These can be used alone or in combination of two or more.

[0111] Among the above organic solvents, carbonate-based organic solvents can be preferably used. Examples of cyclic carbonates include ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC). Representative linear carbonates include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), and ethyl propyl carbonate (EPC).

[0112] The above lithium salts can be used without limitation lithium salts commonly used in electrolytes of lithium secondary batteries such as LiPF6, LiAsF6, LiCF3SO3, LiN(CF3SO2)2, LiBF4, LiBF6, LiSbF6, LiN(C2F5SO2)2, LiAlO4, LiAlCl4, LiSO3CF3, and LiClO4. These can be used alone or in combination of two or more.

[0113] In addition, the above electrolyte further contains additives. For example, as the above additives, in order to stably form a SEI film, any one selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, cyclic sulfite, saturated sultone, unsaturated sultone, acyclic sulfone, lithium oxalyl difluoroborate (LiODFB), and derivatives thereof, or a mixture of two or more of these can be used, but not limited thereto.

[0114] Examples of the above cyclic sulfite include ethylene sulfite, methyl ethylene sulfite, ethyl ethylene sulfite, 4,5-dimethyl ethylene sulfite, 4,5-diethyl ethylene sulfite, propylene sulfite, 4,5-dimethyl propylene sulfite, 4,5-diethyl propylene sulfite, 4,6-dimethyl propylene sulfite, 4,6-diethyl propylene sulfite, 1,3-butylene glycol sulfite, etc. Examples of the saturated sultone include 1,3-propane sultone and 1,4-butane sultone. Examples of the unsaturated sultone include ethene sultone, 1,3-propene sultone, 1,4-butene sultone, 1-methyl-1,3-propene sultone, etc. Examples of the acyclic sulfone include divinyl sulfone, dimethyl sulfone, diethyl sulfone, methyl ethyl sulfone, methyl vinyl sulfone, etc.

[0115] Such an additive is added to the above electrolyte to improve the low-temperature output characteristics by forming a robust SEI film on the negative electrode, and of course, to suppress the decomposition of the positive electrode surface that may occur during the operation of high-temperature cycles and prevent the oxidation reaction of the electrolyte.

[0116] <Activation device for secondary battery> FIG. 9 is a conceptual diagram of an activation device for a lithium secondary battery according to the present invention. Referring to FIG. 9, the activation device 100 of the present invention includes a formation unit 110 configured to pressurize while charging and discharging the battery, and a roll-pressing unit 120 including an upper pressure roller and a lower pressure roller, and pressurizing with the battery interposed between the upper pressure roller and the lower pressure roller.

[0117] In addition, the activation device of the present invention further includes a transfer unit 130 for taking out and carrying in / out a battery between the formation unit 110 and the roll pressing unit 120. The transfer unit 130 includes a pickup unit for carrying out or carrying in a battery housed in the formation unit 110 or the roll pressing unit 120, a drive unit for moving the pickup unit, and a control unit for controlling the operations of the pickup unit and the drive unit.

[0118] During the formation process, in order to perform the roll pressing of the present invention by the roll pressing unit, it is necessary to transfer the battery housed in the formation unit 110 to the roll pressing unit 120. The transfer unit 130 is configured to carry out the battery from the formation unit 110 and transfer it to the roll pressing unit 120, or to carry out the battery for which the roll pressing has been completed from the roll pressing unit 120 and transfer it to the formation unit 110.

[0119] The pickup unit is configured to lift the battery so as to be able to carry out the battery housed in the formation unit or the roll pressing unit, move it to the roll pressing unit or the formation unit by the drive unit, and lower the battery to the roll pressing unit or the formation unit. In one specific example, the pickup unit can be a robot arm.

[0120] And the control unit controls the operations of the drive units of these pickup units.

[0121] The formation unit is configured to pressurize the battery while charging and discharging the battery. In one specific example, the formation unit may include a frame for housing a plurality of battery cells, a charge / discharge unit connected to the electrode leads of the battery to charge and discharge the battery, a plurality of pressure plates for pressurizing both sides of the battery, and a drive unit for moving the plurality of pressure plates.

[0122] FIG. 10 is a perspective view of a roll pressing unit according to an embodiment of the present invention, FIG. 11 is a top view of the roll pressing unit, and FIG. 12 is a front view of the roll pressing unit. Referring to these drawings, the roll pressing unit of the present invention includes an upper pressing roller 121 and a lower pressing roller 122, a driving unit 123 that drives the upper pressing roller and the lower pressing roller to rotate, and a pressing cylinder 124 that causes the upper pressing roller to move in the direction of the lower pressing roller or in the opposite direction.

[0123] Referring to FIGS. 3, 4, and 10 to 12, the upper pressing roller 121 and the lower pressing roller 122 are means for contacting the battery and pressing the battery. The upper pressing roller 121 presses the upper surface of the secondary battery B, and the lower pressing roller 122 presses the lower surface of the secondary battery B.

[0124] The driving unit 123 is located on one side of the upper pressing roller 121 and the lower pressing roller 122, and applies a driving force so that the upper pressing roller and the lower pressing roller perform a rotational motion.

[0125] The pressing cylinder 124 is means for adjusting the load applied to the battery by adjusting the distance between the upper pressing roller 121 and the lower pressing roller 122, and causes the upper pressing roller 121 to reciprocate in the direction of the lower pressing roller 122 or in the opposite direction. The closer the distance between the upper pressing roller and the lower pressing roller, the greater the force applied to the battery, and the wider the distance, the smaller the force applied to the battery.

[0126] Such an activation device of the present invention includes a roll pressing unit, and since the relatively thin sliding part can be pressed with the same force as the flat part, it is possible to prevent the phenomenon of gas being trapped at that part and improve the performance of the battery.

[0127] Hereinafter, the present invention will be described in more detail with reference to examples and the like. However, the configurations described in the examples described in this specification are merely examples of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that there can be various equivalents and modifications that can replace them at the time of this application.

[0128] <Manufacturing Example: Manufacturing of Lithium Secondary Battery> As the positive electrode active material, 95 parts by weight of LiNi 0.8 Co 0.1 Mn 0.1 O2, 0.9 part by weight of Li6Co as a positive electrode additive 0.7 Zn 0.3 O4, 1.6 parts by weight of PVDF as a binder, and 2.5 parts by weight of carbon black as a conductive material were weighed and mixed in an N-methylpyrrolidone (NMP) solvent to produce a slurry for the positive electrode mixture layer. After applying the above slurry for the mixture layer to an aluminum foil and drying it, it was rolled to form a positive electrode having a positive electrode mixture layer (average thickness: 130 μm).

[0129] 85 parts by weight of natural graphite as a carbon-based active material, 5 parts by weight of SiO (silicon oxide) as a silicon-based active material, 6 parts by weight of carbon black as a conductive material, and 4 parts by weight of PVDF as a binder were mixed in an N-methylpyrrolidone solvent to produce a slurry for the negative electrode mixture layer, and it was applied to a copper foil to produce a negative electrode having a negative electrode mixture layer (average thickness: 180 μm).

[0130] A separator (thickness: about 16 μm) made of a porous polyethylene (PE) film was interposed between each of the manufactured positive and negative electrodes and laminated to produce an electrode assembly. After placing the electrode assembly inside a battery case, an electrolyte was injected into the case, and then it was left at room temperature for 3 days so that the electrolyte was sufficiently impregnated to manufacture a lithium secondary battery. The above electrolyte was prepared by injecting an electrolyte in which 1 M LiPF6 was dissolved into an organic solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a composition ratio of 3:7 (volume ratio) to complete the battery.

[0131] <Example 1> A lithium secondary battery assembled in the above manufacturing example was prepared, aged at room temperature of 25°C for 24 hours for pre-aging, and the pre-aged secondary battery was roll-pressed twice in the edge direction where the electrode lead was located from the central part of the battery using the roll pressing part shown in FIG. 10. At this time, the linear pressure applied to the battery by the roll pressing part was set to 40 kfg / cm. Then, the battery was mounted on the formation part shown in FIG. 1, and charged while pressurizing the battery until it reached the level of SOC 60% to complete the formation process. At this time, the charging rate was 0.6C, and the surface pressure applied to the battery was 5.0 kgf / cm 2 It was.

[0132] Thereafter, the secondary battery was subjected to high-temperature aging at a temperature of 60°C for 24 hours and room-temperature aging at a temperature of 23°C for 48 hours. The process of fully charging and fully discharging the aged secondary battery was performed to complete the manufacture of the secondary battery.

[0133] <Example 2> A lithium secondary battery assembled in the above manufacturing example was prepared and aged at room temperature of 25°C for 24 hours for pre-aging. After mounting the pre-aged secondary battery on the formation part shown in FIG. 1, it was charged at a charging rate of 0.2C until the charging depth of the secondary battery reached SOC 17%, and the first formation stage was performed while pressurizing the battery with a pressure of 0.5 kgf / cm 2 Then, the secondary battery was taken out from the formation part and roll-pressed twice in the edge direction where the electrode lead was located from the central part of the battery using the roll pressing part shown in FIG. 10. At this time, the linear pressure applied to the battery by the roll pressing part was set to 40 kfg / cm. Then, the secondary battery was taken out from the roll pressing part, the secondary battery was mounted again on the above formation part, and charged at a charging rate of 1.0C until the charging depth of the secondary battery reached SOC 60%, and the second formation stage was performed while pressurizing the battery with a pressure of 5.0 kgf / cm.

[0134] Thereafter, the secondary battery was subjected to high-temperature aging at a temperature of 60°C for 24 hours and normal-temperature aging at a temperature of 23°C for 48 hours. The process of fully charging and fully discharging the aged secondary battery was performed, and the manufacturing of the secondary battery was completed.

[0135] <Comparative Example> In the above Example 1, a secondary battery was manufactured in the same manner as in Example 1 except that the roll pressing process by the roll pressing unit was omitted.

[0136] <Experimental Example: Observation of the Presence or Absence of Lithium Deposition> Each of the secondary batteries manufactured in the above Examples and Comparative Examples was charged at a constant current of 0.33C, cut off at 4.2V, charged at a constant voltage, and then cut off at 0.05C, and discharged at 0.5C 3.0V. This was taken as one cycle, and after performing 100 cycles of charge and discharge, the battery was disassembled to observe whether lithium was deposited.

[0137]

Table 1

[0138] In the batteries of the Examples, lithium was not deposited, but in the batteries of the Comparative Example, lithium was deposited. FIG. 13 is a photograph of the negative electrode taken after disassembling the secondary battery manufactured according to the Comparative Example and repeating the charge and discharge according to the above Experimental Example. Referring to FIG. 13, it can be confirmed that lithium was deposited in the edge region of the negative electrode, that is, the region where the sliding portion is located. This is judged to be the effect of pressing the sliding portion by performing the roll pressing process before or during the formation process.

[0139] As described above, the activation method and activation device according to the present invention can suppress the trapping of internal gas in the sliding portion and prevent the risk of local charging non-uniformity and lithium deposition.

Claims

1. A pre - aging process of aging the assembled lithium secondary battery at room temperature, A formation process of charging the lithium secondary battery, Including a roll - pressing process of pressing the lithium secondary battery using a pressure roller, In the roll - pressing process, pressure is applied from the central part of the lithium secondary battery towards the edge where the electrode lead is located, The roll - pressing process is performed during the formation process of charging the secondary battery to form a SEI (Solid Electrolyte Interface) coating layer on the negative electrode, The formation process is a process of charging the secondary battery at an SOC of 40 - 70%, A method for activating a lithium secondary battery.

2. The roll - pressing process is performed before the formation process. The method for activating a lithium secondary battery according to Claim 1.

3. The roll - pressing process is performed before and during the formation process respectively. The method for activating a lithium secondary battery according to Claim 1.

4. The roll - pressing process is performed 2 to 5 times. The method for activating a lithium secondary battery according to Claim 1.

5. The roll - pressing process presses the lithium secondary battery with a linear pressure of 20 - 60 kgf / cm. The method for activating a lithium secondary battery according to Claim 1.

6. The pressure roller is composed of an upper pressure roller and a lower pressure roller, The lithium secondary battery is pressed while passing between the upper pressure roller and the lower pressure roller. The method for activating a lithium secondary battery according to Claim 1.

7. The formation process Includes a process of applying surface pressure to the lithium secondary battery during charging. The method for activating a lithium secondary battery according to Claim 1.

8. The formation process Is composed of a plurality of formation stages set so that the end - of - charge SOC is different, In each of the plurality of formation stages, one or more conditions selected from each charging rate and the surface pressure applied to the lithium secondary battery are set to be different. The method for activating a lithium secondary battery according to Claim 7.

9. Further includes an aging process of aging the lithium secondary battery after the formation process is completed. The method for activating a lithium secondary battery according to Claim 1.

10. A method for manufacturing a pouch-type secondary battery, comprising a process of assembling cells and a process of activating the battery, wherein the process of activating the battery is performed by the method for activating a lithium secondary battery according to any one of claims 1 to 9.

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