Electrolyte immersion device for secondary battery, electrolyte immersion method for secondary battery, and method for activating secondary battery

Abstract

According to one embodiment of the present disclosure, an electrolyte impregnation device for a secondary battery comprises: a transfer part configured to transfer the secondary battery in a first direction; and a magnetic field applying section for applying a magnetic field in a second direction to the secondary battery transferred by the transfer section. By applying a magnetic field to the electrolyte flowing in the first direction, magnetohydrodynamic convective flow is caused in the electrolyte, in particular micro magnetohydrodynamic convective flow is generated in the vicinity of the electrode. And a synergistic effect of this flow and buoyancy of air bubbles applied to the surface of the electrode causes the air bubbles to be moved to the airbag portion, thereby removing the air bubbles from the electrode assembly, thereby improving the impregnation performance of the electrolyte.

Description

Technical Field

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0027833, filed on March 2, 2023.

[0002] The present disclosure relates to an electrolyte impregnation device for improving the wetting performance of an electrolyte of a secondary battery, an electrolyte impregnation method of a secondary battery, and a method for activating a secondary battery using the device and the method. Background Art

[0003] A secondary battery capable of repeated charge and discharge includes an electrode assembly, a battery case containing the electrode assembly, and an electrolyte disposed in the battery case to activate the electrode assembly. The electrode assembly is formed by placing a separator between a positive plate and a negative plate, the positive plate is formed by coating a positive electrode active material on a positive electrode collector, the negative plate is formed by coating a negative electrode active material on a negative electrode collector, and the electrode assembly may be made of a jelly roll type, a stacked type, etc. according to the type of the battery case, and may be housed inside the battery case.

[0004] The battery case serves as an exterior material that maintains the shape of the battery and protects it from external impact, and secondary batteries may be classified into a cylindrical type, a prismatic type, and a pouch type according to the type of the battery case.

[0005] A secondary battery is manufactured by having an electrode assembly contained in a battery case and an electrolyte injected into the battery case. In order to make the secondary battery have high capacity, high energy density and long life, the electrolyte should be injected into the interior according to the designed capacity, and the electrode assembly should be completely impregnated with the electrolyte through an aging process under certain temperature and humidity conditions for a certain period of time, so that the electrode reaction between the electrodes can be actively carried out.

[0006] If the content of the electrolyte is less than the designed amount, the desired electrochemical performance cannot be achieved, and the life of the secondary battery is sharply reduced. In addition, if the electrode assembly is not completely immersed in the electrolyte, the reaction between the electrodes is not smooth, resulting in high resistance and a sharp drop in the output characteristics and capacity of the battery, which leads to reduced battery performance and shortened life. In addition, high resistance can cause the battery to heat up or explode. Therefore, injecting a precisely designed amount of electrolyte and allowing the electrolyte to be fully impregnated into the electrode assembly is one of the important issues that determine the performance and life of the secondary battery.

[0007] In particular, in recent years, as the demand for batteries having high energy density has increased, the loading amount of electrodes has increased, and as the loading amount of electrodes has increased, it may be difficult for the electrolyte to be impregnated with respect to the rolled electrodes.

[0008] In order to improve the impregnation performance of the electrolyte, Patent Document 1 discloses a technology for removing bubbles in the electrolyte by vibrating the battery case, but this method removes bubbles in the electrolyte by applying physical external force to the battery. Although large-sized bubbles can be removed, extremely small-sized bubbles may be generated by applying vibration, and it is not sufficient to remove bubbles formed on the surface of the electrode.

[0009] When bubbles exist on the electrode surface, they hinder the impregnation of the electrolyte. Therefore, it is necessary to develop a technology to effectively remove the bubbles on the surface of the electrode to improve the impregnation performance of the electrolyte. Summary of the invention

[0010] Technical issues

[0011] The present disclosure is to provide an electrolyte impregnation device and method for improving the impregnation performance of an electrolyte by effectively removing bubbles on an electrode surface, and a method for activating a secondary battery using the electrolyte impregnation device and method.

[0012] Technical Solution

[0013] According to one embodiment of the present disclosure, there is provided an electrolyte impregnation device for a secondary battery, the secondary battery comprising: a housing portion in which an electrode assembly and an electrolyte are stored; and an airbag portion disposed on one side of the housing portion. The electrolyte impregnation device comprises: a transfer portion configured to transfer the secondary battery in a first direction; and a magnetic field applying portion configured to apply a magnetic field in a second direction to the secondary battery transferred by the transfer portion.

[0014] In a specific example, the second direction may be determined such that a third direction from the accommodating portion toward the airbag portion is orthogonal to a plane formed by the first direction and the second direction.

[0015] In a specific example, the transfer part may include: a carrier having an accommodation space for storing the secondary battery; a conveyor belt for transferring the carrier; and a driving part for driving the conveyor belt in the first direction.

[0016] In a specific example, the magnetic field applying part may include a permanent magnet or an electromagnet.

[0017] According to another embodiment of the present disclosure, there is provided a method for impregnating an electrolyte of a secondary battery, the secondary battery comprising: a receiving portion in which an electrode assembly and an electrolyte are stored; and an air bag portion disposed on one side of the receiving portion. The method for impregnating the electrolyte comprises the following processes: transferring the secondary battery in a first direction; and applying a magnetic field to the transferred secondary battery in a second direction.

[0018] In a specific example, during the process of applying the magnetic field, the second direction may be determined such that a third direction from the accommodating portion toward the airbag portion is orthogonal to a plane formed by the first direction and the second direction.

[0019] In a specific example, during the process of applying the magnetic field, the magnitude of the applied magnetic field can be in the range of 0.1 T to 100 T.

[0020] According to another embodiment of the present disclosure, a method for activating a secondary battery is provided, the secondary battery comprising: a housing portion in which an electrode assembly and an electrolyte are stored; and an air bag portion disposed at one side of the housing portion. The method for activating a secondary battery comprises: a pre-aging process for impregnating an electrode assembly of the secondary battery with an electrolyte; a primary charging process for charging the pre-aged secondary battery until a state of charge (SOC) within a predetermined range is reached; and an aging process for aging the secondary battery, the pre-aging process comprising the following processes: transferring the secondary battery in a first direction; and applying a magnetic field to the transferred secondary battery in a second direction.

[0021] In a specific example, during the process of applying the magnetic field, the second direction may be determined such that a third direction from the accommodating portion toward the airbag portion is orthogonal to a plane formed by the first direction and the second direction.

[0022] In a specific example, the initial charging process may be set such that the depth of charge at which the charging of the secondary battery is terminated is within a range of SOC 20% to SOC 80%.

[0023] In a specific example, the initial charging process may include a process of performing charging while the secondary battery is under pressure.

[0024] In a specific example, the aging process may include: a high temperature aging process, in which the secondary battery is aged within a temperature range of 50°C to 80°C; and a room temperature aging process, in which the secondary battery is aged within a temperature range of 18°C ​​to 30°C.

[0025] Beneficial effects

[0026] According to the electrolyte impregnation device and method disclosed in the present invention, a magnetic field is applied to the electrolyte flowing along a first direction, thereby causing magnetohydrodynamic convection flow in the electrolyte, especially causing tiny magnetohydrodynamic convection flow near the electrode, so that under the synergistic effect of this flow force and the buoyancy of the bubbles, the bubbles on the surface of the electrode are moved to the airbag part, thereby removing the bubbles in the electrode assembly and improving the impregnation performance of the electrolyte.

[0027] The activation method according to the present disclosure can cause such magnetohydrodynamic convection flow during the pre-aging process to remove bubbles on the surface of the electrode, thereby improving the impregnation efficiency of the electrolyte and further shortening the time required for the pre-aging process. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a block diagram showing an electrolyte impregnation device for a secondary battery according to one embodiment.

[0029] Figure 2 is an exploded perspective view of a pouch-type secondary battery according to one embodiment.

[0030] Figure 3 is a schematic diagram of a pouch-type secondary battery according to one embodiment.

[0031] Figure 4 is a view showing an electrolyte impregnation device of a secondary battery according to one embodiment.

[0032] Figure 5 is an upper view of an electrolyte impregnation device of a secondary battery according to one embodiment.

[0033] Figure 6 is a flowchart showing an electrolyte impregnation method of a secondary battery according to one embodiment.

[0034] Figure 7 is a flowchart illustrating a method of activating a secondary battery according to one embodiment.

[0035] [reference numerals list]

[0036] 10: Secondary battery

[0037] 100: Electrolyte impregnation device

[0038] 110: Transfer Department

[0039] 120: Magnetic field applying unit DETAILED DESCRIPTION

[0040] Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention belongs can implement the present invention. However, the present invention can be implemented in various forms and is not limited to the following embodiments.

[0041] In order to clearly illustrate the present invention, parts that are irrelevant to the description or detailed description of the prior art that may unnecessarily obscure the gist of the present invention are omitted. When components in the drawings are marked with figure numerals, the same or similar figure numerals are used for the same or similar components throughout the specification.

[0042] In addition, the terms and words used in this specification and claims should not be understood according to their ordinary or dictionary meanings, but should be interpreted with meanings and concepts consistent with the technical ideas of the present invention based on the principle that the inventor can define the concepts of terms according to his own wishes.

[0043] Electrolyte impregnation device for secondary battery

[0044] [First embodiment]

[0045] Figure 1 is a block diagram showing an electrolyte impregnation device for a secondary battery according to one embodiment.

[0046] Reference Figure 1 , the electrolyte impregnation device 100 for a secondary battery may include: a transfer part 110 configured to transfer a secondary battery in a first direction; and a magnetic field applying part 120, which applies a magnetic field to the secondary battery transferred by the transfer part in a second direction. According to one embodiment of the present disclosure, when the magnetic field formed by the magnetic field applying part acts on the electrolyte of the secondary battery transferred within the magnetic field, thereby generating magnetic field-induced magnetohydrodynamic (MHD) convection in the electrolyte, the electrolyte impregnation device 100 for the secondary battery can remove bubbles on the surface of the electrode.

[0047] When bubbles exist on the surface of the electrode of a secondary battery, the bubbles hinder the wetting of the electrolyte on the electrode, but when magnetic field-induced magnetohydrodynamic convection is formed in the electrolyte, the force caused by the magnetohydrodynamic convection acts on the bubbles and causes the bubbles to fall off the surface of the electrode, thereby ensuring better impregnation of the electrolyte on the electrode.

[0048] The transfer part 110 is not particularly limited as long as it can transfer the secondary battery in one direction. The transfer part 110 is used to transfer the secondary battery and generate a kinetic electromotive force in the electrolyte flowing in the same direction as the secondary battery when a magnetic field is applied.

[0049] The magnetic field applying unit 120 applies a magnetic field to the secondary battery being transferred, and generates magnetohydrodynamic convection by interaction with the kinetic electromotive force of the electrolyte. The bubbles on the surface of the electrode are removed by the magnetohydrodynamic convection. When a magnetic field is applied to the flowing electrolyte, the electric field and the magnetic field cause magnetohydrodynamic convection to flow by the Lorentz force, and tiny magnetohydrodynamic convection flows occur near the electrode. Small-sized bubbles can be effectively removed by magnetohydrodynamic convection flow. In addition, the magnetic field applying unit can be used to increase the mean free path of ions near the surface of the electrode, thereby increasing the amount of charge.

[0050] According to an embodiment of the present disclosure, the magnetic field applying unit 120 may include a permanent magnet or an electromagnet, preferably an electromagnet. The electromagnet is preferably capable of periodically changing the direction of the magnetic field to increase the flow in the electrolyte.

[0051] According to one embodiment of the present disclosure, the secondary battery may be a lithium secondary battery, and more specifically, may be a pouch-type secondary battery. Figure 2 is an exploded perspective view of a pouch-type secondary battery according to one embodiment, Figure 3 is a schematic diagram of a pouch-type secondary battery according to one embodiment.

[0052] Referring to these views, a pouch-type secondary battery 10 according to one embodiment may be a sealed form in which an electrode assembly 11 is built into a storage space 12a of a pouch-type battery case 12. The pouch-type secondary battery 10 according to one embodiment may include a receiving portion 13 in which the electrode assembly 11 and an electrolyte (not shown) are stored, and an airbag portion 14 disposed on one side of the receiving portion.

[0053] The air bag portion 14 of the secondary battery is a space for capturing gas generated during activation of the secondary battery.

[0054] The electrode assembly 11 is formed by alternately stacking electrodes and separators. First, an electrode slurry mixed with an electrode active material, a binder, a conductive material, and a solvent is applied to a positive electrode collector and a negative electrode collector to manufacture electrodes such as a positive electrode and a negative electrode. Then, a separator is stacked between the electrodes to manufacture the electrode assembly 11. The pouch-type secondary battery 10 can be manufactured by inserting the manufactured electrode assembly 11 into a pouch-type battery case 12, injecting an electrolyte into the pouch-type battery case 12, and sealing the pouch-type battery case 12.

[0055] The electrode assembly 11 includes electrode tabs 15a and 15b. The electrode tabs 15a and 15b are respectively connected to the positive electrode and the negative electrode of the electrode assembly 11, and protrude outward from the electrode assembly 11, thereby providing a path for electrons to move between the inside and the outside of the electrode assembly 11. The electrode collector of the electrode assembly 11 includes a portion to which an electrode active material is applied and an end portion to which an electrode active material is not applied (in other words, an uncoated portion). The electrode tabs 15a and 15b can be formed by cutting the uncoated portion, or can be formed by connecting a separate conductive member to the uncoated portion by ultrasonic welding or the like. These electrode tabs 15a and 15b can protrude in different directions of the electrode assembly 11, but can also be formed to protrude in multiple directions, such as but not limited to protruding side by side in the same direction from one side.

[0056] The electrode tabs 15a, 15b of the electrode assembly 11 may be connected to electrode leads 16a, 16b that supply power to the outside of the secondary battery 10, such as by spot welding. In addition, a portion of the electrode leads 16a, 16b may be surrounded by insulating portions 17a, 17b. The insulating portions 17a, 17b may be limited to the side edges S of the upper and lower portions of the battery housing 12 that are heat-melted, so that the electrode leads 16a, 16b may be bonded to the battery housing 12. In addition, the electricity generated from the electrode assembly 11 is prevented from flowing to the battery housing 12 through the electrode leads 16a, 16b, and the sealing of the battery housing 12 is maintained. Therefore, these insulating portions 17a, 17b are made of non-conductive materials that cannot conduct electricity well. Generally, as the insulating portions 17a, 17b, insulating tapes that are easily attached to the electrode leads 16a, 16b and are relatively thin are generally used, but various members may be used without limitation as long as the electrode leads 16a, 16b can be insulated.

[0057] One end of the electrode leads 16a, 16b may be connected to the electrode tabs 15a, 15b, and the other ends of the electrode leads 16a, 16b may protrude to the outside of the battery case 12, respectively. In other words, the electrode leads 16a, 16b may include: a positive electrode lead 16a connected to the positive electrode tab 15a at one end and extending in the direction in which the positive electrode tab 15a protrudes; and a negative electrode lead 16b connected to the negative electrode tab 15b at one end and extending in the direction in which the negative electrode tab 15b protrudes. At the same time, both the positive electrode lead 16a and the negative electrode lead 16b may protrude from the outside of the battery case 12 at the other end. Therefore, the power generated in the electrode assembly 11 can be supplied to the outside. In addition, since the positive electrode tab 15a and the negative electrode tab 15b are each formed to protrude in different directions, the positive electrode lead 16a and the negative electrode lead 16b may also each extend in different directions.

[0058] According to one embodiment, the second direction may be determined such that a third direction (z-axis direction) from the accommodating portion 13 toward the airbag portion 14 is orthogonal to a plane formed by the first direction (x-axis direction) and the second direction (y-axis direction). The first direction is a transfer direction of the secondary battery, and the second direction is an application direction of the magnetic field.

[0059] When a magnetic field is formed around the secondary battery transferred in the first direction (x-axis direction), a kinetic electromotive force is generated in the electrolyte fluid inside the secondary battery, and the electrolyte fluid becomes charged. The charged electrolyte fluid is subjected to the force of the electromotive force and the magnetic field, and magnetohydrodynamic convection is generated in the direction of the Lorentz force. In view of this mechanism of generating magnetohydrodynamic convection, it is preferred that the second direction is set so that the direction of magnetohydrodynamic convection is a third direction from the accommodating portion 13 toward the airbag portion 14.

[0060] In particular, the bubbles in the electrolyte are subjected to buoyancy in the opposite direction to gravity. When the direction of the buoyancy is consistent with the third direction, the bubbles on the surface of the electrode can be more effectively moved to the airbag portion 14 through the synergistic effect of magnetohydrodynamic convection and buoyancy acting in the third direction.

[0061] [Second embodiment]

[0062] Figures 4 to 5 is a view showing an electrolyte impregnation device for a secondary battery according to an embodiment. In the electrolyte impregnation device for a secondary battery, the transfer portion 110' may be used as Figure 1 An alternative to the transfer unit 100.

[0063] Reference Figure 4 and Figure 5 , the transfer portion 110 ′ may include a carrier 111 , a conveyor belt 112 , and a driving roller 113 a .

[0064] The carrier 111 may include a storage space 111a for accommodating the secondary battery 10. The accommodating space 111a may have a volume such that the secondary battery 10 may be inserted therein, and may be configured to be configured to be compatible with the storage space 111a. Figure 4 As shown, the carrier may be configured to allow the secondary battery 10 to be transferred in an upright state with the receiving portion 13 of the secondary battery 10 located below and the airbag portion 14 located above.

[0065] The carrier 111 is configured to transfer the secondary battery 10 in an upright state, so that the area of ​​the electrode assembly 11 and the electrolyte (not shown) in the receiving portion 13 exposed to the magnetic field can be maximized, thereby improving the efficiency of removing bubbles.

[0066] According to a preferred embodiment, the length of the storage space 111a in the longitudinal direction (y-axis direction) may correspond to the thickness of the receiving portion of the secondary battery 10, and the length of the storage space 111a in the transverse direction (x-axis direction) may correspond to the length of the secondary battery in the width direction (x-axis direction). In addition, in order to increase the magnetic field exposure area of ​​the electrode assembly and the electrolyte located in the receiving portion, it is preferably configured so that the length of the secondary battery inserted into the receiving space 111a is not long.

[0067] The conveyor belt 112 may be configured to transfer the carrier 111. The carrier 111 may be attached to an upper surface of the conveyor belt, or may be configured to be removable.

[0068] The driving portion 113 may be configured to drive the conveyor belt 112 in a first direction (x-axis direction). Such a driving portion may include a driving roller 113a disposed in contact with the conveyor belt 112 at a downstream side of the conveyor belt 112, and a motor (not shown) applying a rotational force to the driving roller 113a.

[0069] According to one embodiment of the present disclosure, in the electrolyte impregnation device 100 of the secondary battery, the magnetic field (MF) formed by the magnetic field applying part 120 acts on the electrolyte of the secondary battery 10 transferred in the magnetic field, thereby generating magnetic field-induced magnetohydrodynamic (MHD) convection in the electrolyte. The bubbles on the surface of the electrode are moved to the air bag part by this magnetohydrodynamic convection and removed from the electrode.

[0070] refer to Figure 5, the magnetic field applying part 120 ; 121 , 122 according to an exemplary embodiment may include a first electromagnet 121 and a second electromagnet 122 respectively disposed at the front and rear of a carrier 111 storing the secondary battery 10 .

[0071] The electrolyte impregnation device of the secondary battery is configured to apply a magnetic field (MF) in the second direction to the secondary battery moving in the first direction, thereby generating a magnetohydrodynamic convection flow in the electrolyte by the Lorentz force. The magnetohydrodynamic convection can move bubbles on the surface of the electrode in the third direction, thereby effectively removing the bubbles on the surface of the electrode.

[0072] Furthermore, through the synergistic effect of the flow force of magnetohydrodynamic convection generated near the electrode and the buoyancy of the bubbles, the bubbles on the surface of the electrode can be moved to the airbag portion, thereby removing the bubbles in the electrode assembly and improving the impregnation performance of the electrolyte.

[0073] Electrolyte impregnation method for secondary battery

[0074] Figure 6 is a flowchart showing an electrolyte impregnation method of a secondary battery according to one embodiment.

[0075] refer to Figures 1 to 6 The method of impregnating a secondary battery with an electrolyte may include: a process P10 of transferring the secondary battery along a first direction; and a process P20 of applying a magnetic field to the transferred secondary battery along a second direction.

[0076] Since the secondary battery has been previously described in detail, a repeated description thereof will be omitted.

[0077] Reference Figure 1 and Figures 4 to 6 , the process P10 of transferring the secondary battery may be performed by the transfer part 110 , 110 ′, and the process P20 of applying the magnetic field may be performed by the magnetic field applying part 120 , and repeated descriptions thereof will be omitted.

[0078] Furthermore, as described above, when the second direction is determined in the process P20 of applying a magnetic field, the second direction is determined so that the third direction from the accommodating portion toward the airbag portion is orthogonal to a plane formed by the first direction and the second direction.

[0079] According to one embodiment of the present disclosure, the magnitude of the magnetic field applied in the process P20 of applying the magnetic field may be in the range of 0.1 T to 100 T, preferably in the range of 0.1 T to 50 T, and more preferably in the range of 0.1 T to 5 T.

[0080] In this method of impregnating an electrolyte of a secondary battery, when a magnetic field is applied along the second direction to the electrolyte flowing along the first direction, a magnetohydrodynamic convection flow is induced by the Lorentz force, and a magnetohydrodynamic convection flow is generated near the electrode, which causes bubbles on the surface of the electrode to move along the third direction.

[0081] The flow force induced by the magnetohydrodynamic convection and the buoyancy of the bubbles can work together to more effectively move the bubbles on the surface of the electrode to the air bag portion, thereby removing the bubbles in the electrode assembly and improving the impregnation performance of the electrolyte.

[0082] Secondary battery activation method

[0083] Figure 7 is a flowchart illustrating a method of activating a secondary battery according to one embodiment.

[0084] refer to Figures 1 to 7 , the method for activating a secondary battery may include: a pre-aging process P100 for impregnating an electrode assembly of the secondary battery with an electrolyte; an initial charging process P200 for charging the pre-aged secondary battery until a state of charge SOC within a predetermined range is reached; an aging process P300 for aging the secondary battery; and the pre-aging process P100 may include a process P10 for transferring the secondary battery along a first direction and a process P20 for applying a magnetic field to the transferred secondary battery along a second direction.

[0085] Since the secondary battery has been previously described in detail, a repeated description thereof will be omitted.

[0086] The pre-aging process P100 may be a process of waiting for the electrode assembly 11 to be sufficiently impregnated with the electrolyte in the secondary battery 10 manufactured by storing the electrode assembly 11 in the battery case 12 , injecting the electrolyte, and sealing the battery case.

[0087] After the electrode assembly 11 and the electrolyte are stored in the battery case 12, in order to perform an electrode reaction by initial charging, the electrolyte must be fully impregnated in advance with the positive electrode, the negative electrode and the separator constituting the electrode assembly. If the initial charging process is performed while the electrolyte is not impregnated, an uncharged area may be generated, resulting in an uneven formation of the SEI film, which may lead to a decrease in battery performance.

[0088] Conventionally, the pre-aging process (P100) is performed by keeping the secondary battery under a constant temperature / humidity state for a predetermined period of time. As the electrolyte gradually penetrates into the electrode, a chemical reaction may occur between the electrolyte and the electrode and bubbles may be generated, which hinders the impregnation of the electrolyte.

[0089] The pre-aging process according to the present disclosure includes a process P10 of transferring the electrolyte and a process P20 of applying a magnetic field, and can induce magnetohydrodynamic convection flow in the electrolyte, so that the bubbles are more effectively transferred to the airbag part 14, and can remove the bubbles on the surface of the electrode, thereby improving the impregnation efficiency of the electrolyte and shortening the pre-aging time.

[0090] Such a pre-aging process may be placing the secondary battery at a temperature range of 18 degrees Celsius to 27 degrees Celsius for 12 hours to 48 hours, wherein the temperature range may be from 18 degrees Celsius to 27 degrees Celsius, preferably from 19 degrees Celsius to 26 degrees Celsius, and more preferably from 20 degrees Celsius to 25 degrees Celsius. In addition, the duration of the pre-aging process may be from 12 hours to 48 hours, preferably from 18 hours to 36 hours.

[0091] The pre-aging process may include a high temperature pre-aging process to improve the electrolyte impregnation efficiency. Such a high temperature pre-aging process may be a process in which the preparatory lithium secondary battery is aged for 12 to 24 hours at a temperature of 40 to 55 degrees Celsius.

[0092] During the pre-aging process, such a high temperature pre-aging process can have the effect of improving the impregnation of the electrolyte, so that the SEI film can be formed more uniformly during the initial charging process, and the risk of lithium precipitation can be avoided as the occurrence of uncharged areas is reduced.

[0093] During the pre-aging process, the transfer process P10 and the process of applying a magnetic field P20 can be performed at an appropriate time point during the early stage of the pre-aging process, the middle stage of the pre-aging process, or the late stage of the pre-aging process, preferably in the early stage of the pre-aging process. Here, the early stage of the pre-aging process can be a time within 12 hours after the secondary battery is manufactured.

[0094] The transfer process P10 and the process of applying a magnetic field P20 have been previously described in detail, and thus a repeated description thereof will be omitted.

[0095] Furthermore, as also described above, when the second direction is determined in the process P20 of applying the magnetic field, the second direction is determined so that the third direction from the accommodating portion to the airbag portion is orthogonal to a plane formed by the first direction and the second direction.

[0096] The initial charging process P200 is a process of charging the secondary battery to a predetermined voltage. The lithium secondary battery is activated by performing the initial charging during the manufacturing process, and in such initial charging, lithium ions from the positive electrode migrate to the negative electrode and are inserted into the negative electrode, wherein a solid electrolyte interface (SEI) film is formed on the surface of the negative electrode.

[0097] Once the SEI film is formed, it acts as an ion tunnel, allowing only lithium ions to pass through. The function of the ion tunnel is to solvate the lithium ions, prevent large molecular weight organic solvent molecules such as lithium salts, EC, DMC or DEC, which move with lithium ions in the electrolyte from being inserted into the graphite negative electrode, and prevent the structure of the negative electrode from collapsing. Once the SEI film is formed, the lithium ions will no longer have side reactions with the graphite negative electrode or other materials, and the amount of charge used to form the SEI film has an irreversible capacity, and no reversible reaction will occur during discharge. Therefore, the electrolyte will not decompose further, and the amount of lithium ions in the electrolyte is reversibly maintained, so that stable charging and discharging can be maintained.

[0098] Therefore, once the SEI film is formed, the amount of lithium ions is reversibly maintained, and the life characteristics of the battery are improved.

[0099] In a specific example, in the above-mentioned initial charging process P200, the charging depth at which charging is terminated can be set within the range of 20% (SOC20%) to 80% (SOC80%) of the capacity (SOC100%) of the lithium secondary battery, or can be set within the range of SOC30% to SOC80%, or can be set within the range of SOC40% to SOC80%, or can be set within the range of SOC50% to SOC75%. This can be appropriately selected based on the material characteristics, capacity, etc. of the secondary battery.

[0100] For the charging conditions in the initial charging process P200, charging can be performed according to conditions known in the art. Specifically, the charging method can be charged by a constant current method until the charging end voltage is reached. In this case, the charging rate (c-rate) can be 0.01 C to 2C, can be 0.1 C to 1.5C, can be 0.2 C to 1C, but is not necessarily limited thereto, and can be appropriately changed according to the material properties of the positive electrode and the negative electrode.

[0101] In addition, the temperature condition of the initial charging process P200 may be 18 degrees Celsius to 28 degrees Celsius, more specifically 19 degrees Celsius to 27 degrees Celsius, and more specifically 20 degrees Celsius to 26 degrees Celsius.

[0102] In addition, the initial charging process P200 may include performing charging while the secondary battery is under pressure. If charging is performed while the secondary battery is pressurized, it has the effect of preventing the gas generated during the charging process from being trapped inside the electrode assembly. And such pressurization may be performed by a pressurizing jig configured to pressurize both sides of the secondary battery.

[0103] In addition, the initial charging process P200 can be a one-step charging without setting a pause period until the charging depth for ending charging is reached, or the initial charging process can be divided into multiple steps until a set charging end voltage is reached, and the initial charging process can be performed by changing the charging conditions and pressure conditions of each step.

[0104] The aging process P300 may be a process of aging the secondary battery to stabilize the SEI film formed by the initial charging process P200.

[0105] According to one embodiment, the aging process P300 may include: a high temperature aging process, in which the secondary battery is aged within a temperature range of 50°C to 80°C; and a room temperature aging process, in which the secondary battery is aged within a temperature range of 18°C ​​to 30°C.

[0106] The high temperature aging process has the effect of further accelerating the stabilization of the SEI film formed during the initial charging process.

[0107] The high temperature aging process can be carried out in a temperature range of 50 degrees Celsius to 80 degrees Celsius, preferably 55 degrees Celsius to 80 degrees Celsius, and more preferably 60 degrees Celsius to 75 degrees Celsius. In addition, the time for high temperature aging can be from 10 hours to 40 hours, preferably from 12 hours to 36 hours, and more preferably from 18 hours to 30 hours.

[0108] If the set temperature during the high temperature aging period is too high or the high temperature aging process is performed for too long, the durability of the SEI film will be reduced, which is not desirable; conversely, if the set temperature during the high temperature aging period is too low or the high temperature aging process is performed for too short a time, the life characteristics of the lithium secondary battery may be reduced.

[0109] The room temperature aging process may be a process of aging the secondary battery at a temperature range of 18° C. to 30° C. for 24 hours to 80 hours.

[0110] The temperature range of the room temperature aging process can be from 18 degrees Celsius to 30 degrees Celsius, preferably from 19 degrees Celsius to 27 degrees Celsius, more preferably from 20 degrees Celsius to 25 degrees Celsius. In addition, the time for room temperature aging can be from 24 hours to 80 hours, preferably from 30 hours to 72 hours, more preferably from 16 hours to 60 hours.

[0111] If the room temperature aging process is performed at an excessively low temperature outside the above range, or is performed for too short a time, the backup lithium secondary battery may not be fully activated, thereby possibly reducing the electrical performance; conversely, if the room temperature aging process is performed at an excessively high temperature, or is performed for too long a time, bulging may occur, or the durability of the SEI film may be reduced.

[0112] Meanwhile, as to the order of the high temperature aging process and the room temperature aging process, it is more preferable to perform the room temperature aging after performing the high temperature aging in terms of stabilization of the SEI film.

[0113] According to one embodiment, after the above-described initial charging process P200 and the aging process P300 , the secondary battery may further include a degassing process to release gas inside the secondary battery to the outside of the secondary battery.

[0114] While the present invention has been shown and described in connection with the particular embodiments, it will be apparent to those skilled in the art that modifications and variations are possible without departing from the spirit and scope of the invention as set forth in the appended claims.

Claims

1. An electrolyte impregnation device for a secondary battery, the secondary battery comprising: a housing portion in which the electrode assembly and the electrolyte are stored; and an airbag portion, the airbag portion being disposed on one side of the accommodating portion, the electrolyte impregnation device comprising: a transfer portion configured to transfer the secondary battery in a first direction; and A magnetic field applying section is configured to apply a magnetic field in a second direction to the secondary battery transferred by the transferring section.

2. The electrolyte impregnation device for a secondary battery according to claim 1, wherein: The second direction is determined such that a third direction from the accommodating portion toward the airbag portion is orthogonal to a plane formed by the first direction and the second direction.

3. The secondary battery electrolyte impregnation device according to claim 1, wherein: The transfer unit comprises: a carrier having a housing space for storing a secondary battery; a conveyor belt for transferring the carrier; and A driving unit is used to drive the conveyor belt in the first direction.

4. The secondary battery electrolyte impregnation device according to claim 1, wherein: The magnetic field applying part includes a permanent magnet or an electromagnet.

5. A method for impregnating an electrolyte of a secondary battery, the secondary battery comprising: a housing portion in which the electrode assembly and the electrolyte are stored; and an airbag portion, the airbag portion being disposed on one side of the accommodating portion; the electrolyte impregnation method comprising the following process: transferring the secondary battery in a first direction; as well as A magnetic field is applied to the transferred secondary battery in a second direction.

6. The method for impregnating a secondary battery with an electrolyte according to claim 5, wherein: During application of the magnetic field, the second direction is determined such that a third direction from the accommodating portion toward the airbag portion is orthogonal to a plane formed by the first direction and the second direction.

7. The method for impregnating a secondary battery with an electrolyte according to claim 5, wherein: During the process of applying the magnetic field, the magnitude of the applied magnetic field is 0.1T to 100T.

8. A method for activating a secondary battery, the secondary battery comprising: a housing portion in which the electrode assembly and the electrolyte are stored; and an airbag portion disposed on one side of the accommodating portion, the method for activating a secondary battery comprising: A pre-aging process for impregnating the electrode assembly of the secondary battery with an electrolyte; an initial charging process for charging the pre-aged secondary battery until a state of charge (SOC) within a predetermined range is reached; and An aging process is used to age the secondary battery. The pre-aging process includes the following processes: transferring the secondary battery in a first direction; and applying a magnetic field to the transferred secondary battery in a second direction.

9. The method for activating a secondary battery according to claim 8, wherein: During application of the magnetic field, the second direction is determined such that a third direction from the accommodating portion toward the airbag portion is orthogonal to a plane formed by the first direction and the second direction.

10. The method for activating a secondary battery according to claim 8, wherein: The primary charging process is set so that the depth of charge at which charging of the secondary battery is terminated is within a range of SOC 20% to SOC 80%.

11. The method for activating a secondary battery according to claim 8, wherein: The primary charging process includes a process of performing charging while the secondary battery is under pressure.

12. The method for activating a secondary battery according to claim 8, wherein: The aging process includes: a high temperature aging process, in which the secondary battery is aged within a temperature range of 50°C to 80°C; and a room temperature aging process, in which the secondary battery is aged within a temperature range of 18°C ​​to 30°C.

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