Activation protocol generation method, activation method and device using the same

Abstract

Provided is a method for generating a charge / discharge protocol including additional charge / discharge operations in an activation method, the activation method including a jig forming operation, an aging operation, and additional charge / discharge operations with respect to an assembled secondary battery. The method for generating the charge / discharge protocol includes: an operation (a) of measuring a rate of increase in thickness of a secondary battery over time while repeatedly charging / discharging between a first voltage and a second voltage higher than the first voltage with respect to any one of the assembled secondary batteries; an operation (b) of performing operation (a) at least once with respect to another secondary battery of the same model as any one secondary battery after fixing the second voltage and changing the first voltage; an operation (c) of determining, as a lower limit voltage, one of the first voltages other than the first voltage at the lowest rate among the measured rates of increase in thickness of the secondary battery; and an operation (d) of setting a protocol to repeatedly charge / discharge between the lower limit voltage and the second voltage.

Description

Technical Field

[0001] The present disclosure relates to a method and apparatus for activating a lithium secondary battery, and more particularly, to a method for generating an activation protocol adapted to apply a specific voltage range, and an activation method and apparatus using the method for generating an activation protocol. This application claims priority to Korean Patent Application No. 10-2020-0134301, filed in Korea on Oct. 16, 2020, the disclosure of which is incorporated herein by reference. Background Art

[0002] Recently, as the demand for portable electronic products such as notebook computers, camcorders, and mobile phones is rapidly increasing, and the development of electric vehicles, energy storage batteries, robots, satellites, etc. is in full swing, active research is being conducted on high-performance secondary batteries that can be repeatedly charged and discharged.

[0003] Currently commercialized secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries. Among them, compared with nickel-based secondary batteries, lithium secondary batteries have almost no memory effect, so they can be freely charged and discharged, and have a very low self-discharge rate and a high energy density. Generally, such secondary batteries can be classified into cylindrical or prismatic can-type secondary batteries and pouch-type secondary batteries depending on the outer casing or application form.

[0004] Depending on the type of external device using the secondary battery, the secondary battery can be used in the form of a single cell or in the form of a module in which a plurality of cells are electrically connected. For example, a small device such as a mobile phone can operate with the output and capacity of one cell for a predetermined period of time, while medium or large devices such as notebook computers, portable DVDs, small personal computers (PCs), electric vehicles, and hybrid electric vehicles need to use a module including a plurality of cells due to output and capacity problems.

[0005] A module is manufactured by connecting a protection circuit or the like to a core group in which a plurality of cells are arranged in series and / or parallel and connected to each other. When prismatic or pouch-type cells are used as unit cells, it is possible to easily manufacture unit cells by stacking wide surfaces to face each other and then connecting electrode terminals to each other using a connecting member such as a bus bar. Therefore, when manufacturing a three-dimensional module having a hexahedral structure, prismatic or pouch-type cells are advantageous as unit cells.

[0006] Since the pouch-type cell is configured with an exterior formed by a pouch case that is a multilayer including a metal layer (foil) and synthetic resin layers coated on the upper and lower surfaces of the metal layer, compared to cylindrical or prismatic cells using metal cans, the pouch-type cell can contribute to significantly reducing the weight of the secondary battery and can be formed into various shapes. In addition, the use of pouch-type cells is gradually increasing.

[0007] Generally, a pouch-type cell is manufactured through a process of assembling the cell and a process of activating the cell.

[0008] A conventional pouch case typically includes a lower case in which an electrode assembly is accommodated and an upper case that seals the upper portion of the lower case. The cell is assembled through the following steps: the electrode assembly is accommodated in the accommodation portion of the lower case, the edge surrounding the accommodation portion of the lower case is adhered to the edge of the upper case corresponding to the front edge, the tightly adhered portion is heat-sealed, the electrolyte is put in, and the remaining portion is vacuum-sealed.

[0009] Since the cell is assembled in a discharged state, it can function as a battery only after being assembled and then charged and activated. This is called the activation or formation process.

[0010] During the activation process, the cell is installed in an activation device that is a predetermined activation process equipment to obtain smooth current flow, and charge / discharge is performed under the conditions necessary for activation. Due to the characteristics of the cell, this activation process must be continued during the first cycle to activate the positive electrode active material and generate a solid electrolyte interface (SEI) on the negative electrode. During the activation process, an SEI is finally formed on the surface of the negative electrode due to the reaction between the negative electrode active material and the electrolyte, and the physical and mechanical integrity of this SEI determines the performance of the cell until the end of the life of the cell and the secondary battery including the cell.

[0011] The cell manufacturing process including the activation process is as follows. After the cell is assembled to have a cavity, a jig formation operation for SEI formation is performed. An aging time is required so that the electrolyte is sufficiently impregnated. An additional charge / discharge operation is required. Gas is generated inside the cell due to charge / discharge. To remove this gas, the cavity is pierced to inhale the gas, and a degassing operation of cutting off unnecessary portions of the case and sealing the case is performed. Then, the cell is inspected and then shipped as a finished product.

[0012] During the degassing operation, when gas is inhaled, the electrolyte inside the monomer also easily leaks. However, if a large number of pores are formed in the electrode active material, the electrolyte is captured in the pores and thus less leaks. An additional charge / discharge operation is performed to form pores in the electrode active material, and thus it is very important. However, when the lead time of the additional charge / discharge operation increases, this causes a delay in the progress of the entire activation process and also causes a reduction in productivity. Therefore, a method for shortening the progress time of the activation process including the additional charge / discharge operation is needed. Summary of the Invention

[0013] Technical problem

[0014] The present disclosure is designed to solve the problems of the related art, and thus the present disclosure is dedicated to providing an activation protocol generation method capable of shortening the lead time of the additional charge / discharge operation.

[0015] The present disclosure is designed to solve the problems of the related art, and thus the present disclosure is dedicated to providing an activation method with a shortened lead time by using the activation protocol generation method.

[0016] The present disclosure is designed to solve the problems of the related art, and thus the present disclosure is dedicated to providing an activation device using the activation protocol generation method.

[0017] Technical solution

[0018] In one aspect of the present disclosure, there is provided a method for generating a charge / discharge protocol for an additional charge / discharge operation included in an activation method, the activation method including a jig forming operation, an aging operation, and an additional charge / discharge operation with respect to an assembled secondary battery, the charge / discharge protocol generation method including: an operation (a) of measuring the rate of increase in the thickness of the secondary battery over time while repeatedly charging / discharging between a first voltage and a second voltage higher than the first voltage with respect to any one of the assembled secondary batteries; an operation (b) of performing at least once the operation (a) with respect to another secondary battery of the same model as any one of the secondary batteries after fixing the second voltage and changing the first voltage; an operation (c) of determining, as a lower limit voltage, one of the first voltages other than the first voltage at the lowest rate among the measured rates of increase in the thickness of the secondary battery; and an operation (d) of setting a protocol to repeatedly charge / discharge between the lower limit voltage and the second voltage.

[0019] The second voltage may be the full charge voltage of the secondary battery, and the first voltage may be a voltage greater than or equal to the full discharge voltage of the secondary battery.

[0020] The full charge voltage may be a voltage that enables the SOC of the secondary battery to have a definite value between 80% and 90%, and the full discharge voltage may be the voltage when the SOC of the secondary battery is 0%.

[0021] The secondary battery thickness increase rate can be obtained by subtracting the thickness of the secondary battery measured before charging / discharging in operation (a) from the thickness of the secondary battery measured after charging / discharging in operation (a) and by dividing the difference between the two thicknesses by the total time taken for charging / discharging.

[0022] In one aspect of the present disclosure, there is provided a method for generating a charge / discharge protocol including additional charge / discharge operations in an activation method, the activation method including a jig formation operation, an aging operation, and an additional charge / discharge operation with respect to an assembled secondary battery, the charge / discharge protocol generation method including: measuring the secondary battery thickness increase rate over time while repeating charge / discharge between the full discharge voltage and the full charge voltage of the secondary battery with respect to any one of the secondary batteries, and setting the measured secondary battery thickness increase rate as a reference; measuring the secondary battery thickness increase rate over time while repeating charge / discharge between a first voltage higher than the full discharge voltage and the full charge voltage with respect to another secondary battery of the same model as any one of the secondary batteries; changing the first voltage, and then performing the operation of measuring the secondary battery thickness increase rate over time while repeating charge / discharge between the changed first voltage and the full charge voltage with respect to another secondary battery of the same model as any one of the secondary batteries at least once; determining a lower limit voltage having a rate greater than the reference from the measured secondary battery thickness increase rates from among the first voltages; and setting a protocol such that charge / discharge is repeated between the lower limit voltage and the full charge voltage.

[0023] The present disclosure also proposes an activation method using this additional charge / discharge activation protocol generation method. The activation method according to the present disclosure includes: a jig formation operation for an assembled secondary battery; an aging operation; and an additional charge / discharge operation, and the additional charge / discharge operation is performed using a charge / discharge protocol obtained by the additional charge / discharge activation protocol generation method according to the present disclosure.

[0024] The present disclosure also provides an activation device capable of performing such an activation method. The activation device according to the present disclosure includes: a charge / discharge device configured to perform charge / discharge with respect to an assembled secondary battery; and a control device configured to control the operation of the charge / discharge device according to a charge / discharge protocol.

[0025] The control device includes: a processing unit, which includes a program module for running an operation (a) of measuring the rate of increase in the thickness of a secondary battery over time while repeatedly charging / discharging any one of the assembled secondary batteries between a first voltage and a second voltage higher than the first voltage; a program module for running at least once an operation of performing the operation (a) with respect to another secondary battery of the same model as any one of the secondary batteries after fixing the second voltage and changing the first voltage; a program module for determining, as a lower limit voltage, one of the first voltages other than the first voltage at which the lowest rate is shown among the measured rates of increase in the thickness of the secondary battery; and a program module for setting a protocol to repeatedly charge / discharge between the lower limit voltage and the second voltage. The control device controls a charge / discharge device to perform an additional charge / discharge operation to form pores in the electrode active material according to the protocol after performing a jig formation charge / discharge for SEI formation on the secondary battery and then having an aging time to sufficiently impregnate the electrolyte.

[0026] The activation device may further include: a thickness measurement unit configured to measure the thickness of the secondary battery. The control device may control the driving and measurement timing of the thickness measurement unit, and the program module of the processing unit may calculate the rate of increase in the thickness of the secondary battery by using the thickness measured by the thickness measurement unit.

[0027] Beneficial effect

[0028] In the additional charge / discharge activation protocol generation method according to the present disclosure and the activation method using the additional charge / discharge activation protocol generation method, the lead time of the additional charge / discharge process can be shortened during the activation process in the production process of a secondary battery including a pouch-type cell. Therefore, the lead time of the entire activation process can be shortened, resulting in an increase in productivity.

[0029] The additional charge / discharge activation process can sufficiently ensure pores in the electrode active material before degassing. According to the present disclosure, since pores can be formed in a short period of time, the defect rate of the residual amount of the electrolyte after degassing can be reduced.

[0030] The activation device according to the present disclosure is optimized for performing the additional charge / discharge activation protocol generation method and the activation method using the additional charge / discharge activation protocol generation method. The activation device only requires sufficient manpower to change the secondary batteries to be charged and discharged one by one, and can automatically perform almost the entire charge / discharge process, thus providing high productivity and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, are used to provide a further understanding of the technical features of the present disclosure. Therefore, the present disclosure is not to be construed as being limited to the accompanying drawings.

[0032] Figure 1 is a flowchart of a method for generating an additional charge / discharge activation protocol according to an embodiment of the present disclosure.

[0033] Figures 2 to 6 shows various charge / discharge protocols that can be used as examples in the method for generating an additional charge / discharge activation protocol according to an embodiment of the present disclosure.

[0034] Figure 7 is a diagram showing Figures 2 to 6 a graph of the rate of increase in the thickness of a secondary battery obtained for each secondary battery after performing charge / discharge.

[0035] Figure 8 is a schematic diagram of an activation device according to another embodiment of the present disclosure. Detailed Description of the Embodiments

[0036] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms used in the specification and the appended claims should not be construed as being limited to general and dictionary meanings, but should be interpreted based on the meanings and concepts corresponding to the technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to appropriately define the terms for the best explanation. Therefore, the description presented herein is only a preferred example for illustrative purposes and is not intended to limit the scope of the present disclosure. Thus, it should be understood that other equivalents and modifications may be made without departing from the scope of the present disclosure.

[0037] In the following embodiments, a secondary battery commonly means a battery in which lithium ions serve as working ions during charging and discharging to induce an electrochemical reaction at the positive electrode and the negative electrode.

[0038] Even when the name of the secondary battery changes depending on the type of electrolyte or separator used in the secondary battery, the type of battery case (or packaging material) for encapsulating the secondary battery, the internal or external structure of the secondary battery, etc., all batteries using lithium ions as working ions need to be interpreted as being included in the category of secondary batteries.

[0039] In addition, a secondary battery is not limited by the number of elements that make up the secondary battery. Therefore, a secondary battery needs to be interpreted as including not only a single cell including an electrode assembly of a positive electrode / a separator / a negative electrode and an electrolyte in one battery case, but also an assembly of single cells, a module in which a plurality of assemblies are connected in series and / or in parallel, a group in which a plurality of modules are connected in series and / or in parallel, and a battery system in which a plurality of groups are connected in series and / or in parallel.

[0040] Examples of secondary battery assemblies and activation processes to which the method according to the present disclosure is applicable are as follows.

[0041] The assembly operation includes accommodating and sealing an electrode assembly and an electrolyte in a battery case in a manufacturing chamber.

[0042] First, an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode is manufactured. The manufacturing of the electrode assembly includes applying an electrode paste including an active material and a binder to an electrode current collector to manufacture the positive electrode and the negative electrode, respectively, and then interposing the separator between the positive electrode and the negative electrode. The manufacturing of the electrode assembly is not particularly limited and can be performed according to known methods. In addition, the electrode assembly is not particularly limited as long as it has a structure including a positive electrode, a negative electrode, and a separator, and the structure can be, for example, a jelly roll type, a stacked type, or a stacked / folded type structure.

[0043] The negative electrode in the electrode assembly may include a carbon-based negative electrode active material. The carbon-based negative electrode active material may be artificial graphite or natural graphite.

[0044] The electrolyte may include an organic solvent and a lithium salt. The organic solvent is not limited as long as it can minimize decomposition due to an oxidation reaction during charging / discharging of the battery and exhibits desired properties. For example, the organic solvent may be a cyclic carbonate, a chain carbonate, an ester, an ether, or a ketone. These may be used alone, or two or more of them may be used in combination. Among the organic solvents, a carbonate-based organic solvent may be preferably used. Examples of the cyclic carbonate include ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC), and representative examples of the chain carbonate include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), and ethyl propyl carbonate (EPC). Lithium salts commonly used in the electrolyte of a lithium secondary battery, such as LiPF6, LiAsF6, LiCF3SO3, LiN(CF3SO2)2, LiBF4, LiBF6, LiSbF6, LiN(C2F5SO2)2, LiAlO4, LiAlCl4, LiSO3CF3, and LiClO4, may be used as the lithium salt without limitation, and these may be used alone, or two or more of them may be used in combination.

[0045] The battery housing may preferably be a pouch made of aluminum laminate sheet.

[0046] Next, the monomer assembled as above is transferred to the formation chamber to continue the activation process. The activation process includes a fixture formation operation for forming SEI, an aging operation for fully impregnating the electrolyte, and an additional charge / discharge operation for forming pores in the electrode active material. The present disclosure particularly proposes a method for generating a charge / discharge protocol in the additional charge / discharge operation.

[0047] The inventors of the present disclosure determined that the activation voltage has a major influence on the formation of pores in the electrode. The present disclosure proposes a method of most preferably determining the charge / discharge voltage range from the viewpoint of productivity of the additional charge / discharge operation by focusing on such a voltage range. When the predetermined charge / discharge voltage range is determined as proposed by the present disclosure and used as a charge / discharge protocol, sufficient pores can be ensured within the same time period, thereby reducing both the lead time of the additional charge / discharge operation and the lead time of the entire activation process.

[0048] The inventors of the present disclosure have completed the present disclosure by finding that when pores are formed in an electrode active material, the thickness of a secondary battery increases, and when the level of the thickness increase of the secondary battery is ascertained while changing a charge / discharge voltage, an appropriate charge / discharge range can be determined.

[0049] A secondary battery has an upper limit that can be physically charged and a lower limit that can be physically discharged. However, in an actual use environment, charging / discharging is not performed until the physical upper and lower limits. Instead, within the physical upper and lower limits of the secondary battery, the use area is appropriately set according to the safety, life, and energy efficiency of the secondary battery, and charging and discharging are performed only within the use area.

[0050] In other words, the lower limit of the use area is set to be higher than the physical limit discharge point, and the upper limit of the use area is set to be lower than the physical limit charge point. The use area can be set differently according to the characteristics of the secondary battery, the use environment, the required charge / discharge capacity, the energy output, etc. In the following, it is defined that the secondary battery is fully discharged (or fully discharged) when the state of the secondary battery reaches the lower limit of the set use area during the discharge process of the secondary battery. It is also defined that the secondary battery is fully charged (or fully charged) when the state of the secondary battery reaches the upper limit of the set use area during the charging process of the secondary battery.

[0051] Conventionally, there is a case where additional charge / discharge is performed by repeating charge / discharge between a full charge voltage and a full discharge voltage. Although the full charge voltage and the full discharge voltage vary depending on the type of the cell, there is a case where charge / discharge is performed, for example, in the range of 4.35 V to 3.0 V. At this time, it takes 750 minutes to form pores in the electrode active material to a desired degree. However, it has been confirmed that when additional charge / discharge is performed using the charge / discharge voltage range obtained by the activation protocol generation method proposed by the present disclosure, the time period for forming pores in the electrode active material can be reduced to 440 minutes. Now, the activation protocol generation method according to the present disclosure will be described in detail with specific examples.

[0052] Figure 1 is a flowchart of a method for generating an additional charge / discharge activation protocol according to an embodiment of the present disclosure.

[0053] Refer to Figure 1 , first, charge / discharge is repeated between a first voltage and a second voltage higher than the first voltage with respect to any one of the assembled secondary batteries while measuring the rate of increase in the thickness of the secondary battery over time [operation (a)].

[0054] The second voltage may be the full charge voltage of the secondary battery, and the first voltage may be a voltage greater than or equal to the full discharge voltage of the secondary battery. The full charge voltage and the full discharge voltage may vary depending on the usage area set as mentioned above. For example, the full charge voltage may be a voltage such that the SOC of the secondary battery can have a certain value between 80% and 90%, and the full discharge voltage may be the voltage when the SOC of the secondary battery is 0%.

[0055] According to this embodiment, as an example, the case where the second voltage is the full charge voltage of the secondary battery and is a voltage such that the SOC of the secondary battery can be 85% is taken. The voltage such that the SOC can be 85% may vary depending on the secondary battery model. However, in the secondary battery described in this embodiment, the voltage is 4.35 V. According to this embodiment, as an example, the case where the first voltage is the full charge voltage of the secondary battery and is a voltage such that the SOC of the secondary battery can be 0% is taken. The voltage such that the SOC can be 0% may vary depending on the secondary battery model. However, in the secondary battery described in this embodiment, the voltage is 3.0 V.

[0056] Then, in operation (a) as the first operation, while charging / discharging is repeated between 3.0 V and 4.35 V with respect to any one secondary battery, the rate of increase in the thickness of the secondary battery over time is measured. The number of repetitions of charging / discharging can be arbitrarily set to one or more times. The rate of increase in the thickness of the secondary battery can be a value obtained by subtracting the thickness of the secondary battery measured before charging / discharging in operation (a) from the thickness of the secondary battery measured after charging / discharging in operation (a) and by dividing the difference between the two thicknesses by the total time taken for charging and discharging.

[0057] For example, the charging / discharging protocol of operation (a) can be as Figure 2 shown. Figures 2 to 6 Shows various charging / discharging protocols that can be used as examples in the additional charging / discharging activation protocol generation method according to an embodiment of the present disclosure.

[0058] After the secondary battery is aged in a state where the SOC is charged to, for example, 65%, in the previous fixture forming operation, additional charging / discharging can be performed, and the additional charging / discharging can be performed according to the additional charging / discharging protocol as Figure 2 shown. When the secondary battery reaches the full charge voltage of 4.35 V by performing additional charging in the SOC 65% state, discharging is performed. When the secondary battery reaches the full discharge voltage of 3.0 V, charging is performed until the secondary battery reaches the full charge voltage again. When the secondary battery reaches the full charge voltage, the secondary battery is discharged until the secondary battery reaches the full discharge voltage again. For example, a cycle including one charge and one discharge is repeated 4 times. The total time period to complete this is 750 minutes. After performing charging / discharging according to the charging / discharging protocol as Figure 2 shown, the rate of increase in the thickness of the secondary battery is obtained. The rate of increase in the thickness of the secondary battery is calculated by subtracting the thickness of the secondary battery measured before charging / discharging from the thickness of the secondary battery measured after charging / discharging and by dividing the difference (thickness change) between the two thicknesses by the total time taken for charging and discharging. Figure 2 The charging / discharging curve of

[0059] Figure 7 can be, for example, a reference. Figure 2 is a graph showing the rate of increase in the thickness of the secondary battery obtained for the secondary battery after performing charging / discharging according to Figure 7 When the thickness change (ΔT) is about 70 μm when the total time taken for charging / discharging is 750 minutes, for example, it is shown as a circle dot in

[0060] Next, after fixing the second voltage and changing the first voltage, the same operation as operation (a) [operation (b)] is performed with respect to another secondary battery of the same model as the previous secondary battery. Operation (b) is performed at least once.

[0061] According to this embodiment, take the case where the second voltage is 4.35 V and the initial first voltage is 3.0 V as an example. Since the initial first voltage is the fully discharged voltage, the changed first voltage can be greater than the fully discharged voltage. For example, the changed first voltage can be 4.0 V as in Figure 3 and Figure 4 , or can be 3.9 V as in Figure 5 and Figure 6 . It is only necessary that the first voltage is less than the second voltage.

[0062] When operation (b) is performed one or more times, operation (b) can be performed by keeping the changed first voltage constant and changing the number of charge / discharge repetitions. For example, Figure 3 and Figure 5 the number of charge / discharge cycles is 4 times, which is the same as the number of charge / discharge cycles of Figure 2 , but Figure 4 and Figure 6 show the case where the number of charge / discharge cycles is 9 times, which is greater than the number of charge / discharge cycles of Figure 2 . In other words, as shown in Figures 3 to 6 , the secondary battery is charged and discharged according to various charge / discharge protocols with different first voltages or different numbers of charge / discharge, and then different secondary battery thickness increase rates are obtained for such different cases.

[0063] One or more secondary battery thickness increase rates obtained by operation (b) can be added as data as further shown in Figure 7 . Figure 7 is a graph showing the secondary battery thickness increase rate obtained for each secondary battery after charge / discharge is performed according to Figures 3 to 6 .

[0064] Subsequently, one of the first voltages, except for the first voltage at the lowest rate among the measured secondary battery thickness increase rates, is determined as the lower limit voltage [operation (c)]. Referring to Figure 7 , when according to Figure 6When charging / discharging is repeated 9 times between 3.9 V and 4.35 V, the rate of increase in the thickness of the secondary battery is the lowest (the slope of the curve is the smallest). Therefore, the lower limit voltage is determined from the first voltages of 4 V and 3.0 V other than 3.9 V. According to this embodiment, when the first voltage is 3.0 V, it takes 750 minutes to repeat charging / discharging 4 times. However, when the first voltage is 4 V, it takes 230 minutes to repeat charging / discharging 4 times, and it takes 440 minutes to repeat charging / discharging 9 times. Therefore, considering that it is advantageous to have a short time taken to complete charging / discharging, 4 V out of 3.0 V and 4 V is suitable as the lower limit voltage and can thus be determined as the lower limit voltage.

[0065] Next, a protocol is set to repeat charging / discharging [operation (d)] between the lower limit voltage and the second voltage. Although the same lower limit voltage is used, when referring to Figure 7 When charging / discharging is repeated 4 times between 4 V and 4.35 V, the thickness change is smaller than when charging / discharging is repeated 9 times between 4 V and 4.35 V. Therefore, the case where the number of charging / discharging times is 9 times is suitable as the case that satisfies the condition of a large thickness change. A large thickness change means that many pores are formed in the electrode active material and thus the volume of the electrode active material expands. Therefore, the newly set charging / discharging protocol in operation (d) is determined to be to repeat charging / discharging 9 times between 4 V and 4.35 V. The additional charging / discharging protocol determined in this way can be used as the established additional charging / discharging protocol in the next additional charging / discharging process.

[0066] According to another embodiment, when operation (a) is performed, the case of following a charging / discharging protocol such as Figure 2 can be used as a reference, that is, a reference point. The result of measuring the rate of increase in the thickness of the secondary battery over time while repeating charging / discharging between the fully discharged voltage and the fully charged voltage is used as the reference.

[0067] Then, when operation (b) is performed, while repeating charging / discharging between the first voltage higher than the fully discharged voltage and the fully charged voltage with respect to another secondary battery of the same model as the previous secondary battery, the rate of increase in the thickness of the secondary battery over time is measured. After further changing the first voltage, operation (b) is further repeated.

[0068] When operation (c) is performed, the lower limit voltage that shows a rate greater than the reference can be determined from the measured rates of increase in the thickness of the secondary battery among the first voltages. Operation (d) can be ended by setting a new additional charging / discharging protocol to repeat charging / discharging between the determined lower limit voltage and the fully charged voltage.

[0069] When additional charging / discharging is performed according to a new additional charging / discharging protocol obtained based on the present disclosure, the rate of increase in the thickness of the secondary battery is greater than the rate of increase in the thickness of the secondary battery in the reference case. In other words, when additional charging / discharging is performed according to a new additional charging / discharging protocol obtained based on the present disclosure, pores can be formed in the electrode active material in a shorter period of time than in the case where additional charging / discharging is performed while repeating charging / discharging between the full discharge voltage and the full charge voltage. This results in an increase in productivity.

[0070] In other words, according to the present disclosure, the charging / discharging voltage range is reduced compared to the reference case, thereby reducing the process lead time. The present disclosure is a method for generating an activation protocol adapted to apply a specific voltage range. The present disclosure proposes to enable ensuring sufficient pores within the same or a shorter period of time as in the prior art.

[0071] The present disclosure also proposes an activation method using this method for generating an additional charging / discharging activation protocol. The activation method according to the present disclosure includes: a jig forming operation for an assembled secondary battery; an aging operation; and an additional charging / discharging operation, and the additional charging / discharging operation is performed using a charging / discharging protocol obtained by the method for generating an additional charging / discharging activation protocol according to the present disclosure.

[0072] The present disclosure also provides an activation device capable of performing such an activation method. Figure 8 is a schematic diagram of an activation device according to another embodiment of the present disclosure.

[0073] Reference Figure 8 , the activation device 100 includes a charging / discharging device 110 and a control device 120.

[0074] The charging / discharging device 110 is capable of charging / discharging an assembled secondary battery. The charging / discharging device 110 is a device for charging / discharging a single cell for activation, and may be an existing charging / discharging device. The charging / discharging device 110 may include a charging / discharging jig, a charging circuit, a discharging circuit, etc.

[0075] The control device 120 controls the operation of the charging / discharging device 110 according to the charging / discharging protocol. The control device 120 is electrically connected to the charging / discharging device 110. The control device 120 controls the charging or discharging of the charging / discharging device 110, and at the same time, controls the switching of the charging or discharging mode.

[0076] For example, the charging circuit of the charging / discharging device 110 supplies power for charging a single cell in the charging mode, and the charging circuit starts and stops operating according to the start signal of the control device 120. In order to perform CC charging, CV charging, or CC-CV charging, the charging circuit includes a constant current circuit and a constant voltage circuit.

[0077] The discharge circuit of the charge / discharge device 110 discharges a single cell in the discharge mode. The discharge circuit also starts and stops operations according to the start signal of the control device 120.

[0078] The control device 120 may include a processing unit 132, a memory unit 134, a display unit 136, and a control unit 138.

[0079] The processing unit 132 includes a program module for performing an operation (a) of measuring the rate of increase in the thickness of a secondary battery over time while repeatedly charging / discharging between a first voltage and a second voltage higher than the first voltage with respect to any one secondary battery; a program module for performing at least one operation of performing operation (a) with respect to another secondary battery of the same model as the any one secondary battery after fixing the second voltage and changing the first voltage; a program module for determining, as the lower limit voltage, one of the first voltages other than the first voltage at which the lowest rate is shown among the measured rates of increase in the thickness of the secondary battery; and a program module for setting a protocol for repeatedly charging / discharging between the lower limit voltage and the second voltage. These program modules can implement the above additional charge / discharge protocol generation method.

[0080] The memory unit 134 is a recording medium for storing control programs and data related to calculations and judgments. For example, the memory unit 134 records the voltage of a single cell measured for each time period while charging / discharging the single cell. The memory unit 134 may measure the electrode thickness before and after the start and end of charging / discharging, and store the difference between the measured electrode thicknesses, that is, the change in the electrode thickness. The memory unit 134 may also record the total time taken for charging / discharging. The display unit 136 may display, for example, a graph as shown in Figure 7 or a result such as the determined lower limit voltage. The display unit 136 may be a display device such as a computer monitor.

[0081] The control unit 138 controls the entire process of the activation device 100 based on the control program stored in the memory unit 134.

[0082] Specifically, as described above, the control unit 138 charges, maintains, and discharges the cell by operating the charge / discharge device 110. The control unit 138 measures the cell voltage for each time period and stores the measurement results in the memory unit 134. The control unit 138 may display the charge / discharge curve together with the stored results on the display unit 136. The control unit 138 may implement an additional charge / discharge protocol generation method according to the present disclosure by operating the processing unit 132. The control unit 138 may store the lower limit voltage as a determination result and the charge / discharge protocol including the lower limit voltage in the memory unit 134, and may display them on the display unit 136.

[0083] The activation device 100 may further include a thickness measurement unit 140 for measuring the thickness of the secondary battery. The control device 120 controls the driving and measurement timing of the thickness measurement unit 140, and may store the thickness measured by the thickness measurement unit 140 in the memory unit 134. The program module of the processing unit 132 may read the thickness and the total time taken for charging / discharging from the memory unit 134 to calculate the rate of increase in the thickness of the secondary battery.

[0084] The activation device 100 is not only used to generate an additional charge / discharge protocol, but also, after performing a formation charge / discharge for SEI formation on the secondary battery and then having an aging time to sufficiently impregnate the electrolyte, controls the charge / discharge device 110 to perform an additional charge / discharge operation according to the protocol to form pores in the electrode active material.

[0085] For example, in the formation charge / discharge operation for SEI formation, when the operator mounts the secondary battery on the charge / discharge device 110 of the activation device 100, the control device 120 controls the charge / discharge device 110 to perform, for example, CC-CV charging with respect to the secondary battery. In the formation operation, there is a preset protocol, so the control is performed according to the preset protocol. For example, in order to form a small number of SEI nuclei at the start of production and then grow them to form a uniform SEI film, there may be a protocol for charging at a rate of 0.1C for about 3 hours until 65% SOC is reached. As another example, there may be a protocol for performing an operation of initially applying a relatively high C-rate current to generate nuclei of the SEI film and a subsequent operation of maintaining a relatively low C-rate current to grow the nuclei. The formation operation may vary at any time.

[0086] For subsequent aging operations, the control device 120 stops driving the charge / discharge device 110. The operator removes the secondary battery and has an aging time in the aging chamber. When the operator reinstalls the aged secondary battery on the charge / discharge device 110 of the activation device 100, the charge / discharge device 110 is driven according to an additional charge / discharge protocol to perform an additional charge / discharge operation on the secondary battery.

[0087] The present disclosure has been described in detail. However, it should be understood that the detailed description and the specific examples, while indicating preferred embodiments of the present disclosure, are given by way of illustration only, since various changes and modifications within the scope of the present disclosure will become apparent to those skilled in the art from this detailed description.

[0088] (Reference numerals)

[0089] 100: Activation device 110: Charge / discharge device

[0090] 120: Control device 132: Processing unit

[0091] 134: Memory unit 136: Display unit

[0092] 138: Control unit 140: Thickness measurement unit

Claims

1. A method for generating a charge / discharge protocol including additional charge / discharge operations in an activation method, the activation method including a jig formation operation, an aging operation, and the additional charge / discharge operations with respect to an assembled secondary battery, the charge / discharge protocol generation method comprising: Operation (a) of measuring the rate of increase in the thickness of a secondary battery over time while repeatedly charging / discharging between a first voltage and a second voltage higher than the first voltage with respect to any one of the assembled secondary batteries; Operation (b) of performing operation (a) at least once with respect to another secondary battery of the same model as the any one secondary battery after fixing the second voltage and changing the first voltage; Operation (c) of determining, as a lower limit voltage, one of the first voltages other than the first voltage at the lowest rate among the measured rates of increase in the thickness of the secondary battery; And Operation (d) of setting a protocol to repeatedly charge / discharge between the lower limit voltage and the second voltage.

2. The method for generating a charging / discharging protocol according to claim 1, wherein, The second voltage is the full charge voltage of the secondary battery, and the first voltage is a voltage greater than or equal to the full discharge voltage of the secondary battery.

3. The method for generating a charging / discharging protocol according to claim 2, wherein, The full charge voltage is a voltage that enables the SOC of the secondary battery to have a determined value between 80% and 90%, and the full discharge voltage is the voltage when the SOC of the secondary battery is 0%.

4. The method for generating a charging / discharging protocol according to claim 1, wherein, The rate of increase in the thickness of the secondary battery is obtained by subtracting the thickness of the secondary battery measured after charging / discharging in operation (a) from the thickness of the secondary battery measured before charging / discharging in operation (a) and dividing the difference between the two thicknesses by the total time taken for charging / discharging.

5. The charging / discharging protocol generation method according to claim 1, wherein, When the lower limit voltage is determined, the first voltage when the total time taken for charging / discharging is relatively short is determined as the lower limit voltage.

6. The method for generating a charging / discharging protocol according to claim 1, wherein, Operation (b) is performed by changing the number of repetitions of charging / discharging.

7. The charging / discharging protocol generation method according to claim 6, wherein, When the protocol is set, the number of repetitions of charging / discharging when the change in the thickness of the secondary battery is relatively large is selected.

8. A method for generating a charge / discharge protocol including additional charge / discharge operations in an activation method, the activation method including a jig formation operation, an aging operation, and the additional charge / discharge operations with respect to an assembled secondary battery, the charge / discharge protocol generation method comprising: Measuring the rate of increase in the thickness of a secondary battery over time while repeatedly charging / discharging between the full discharge voltage and the full charge voltage of the secondary battery with respect to any one of the secondary batteries, and setting the measured rate of increase in the thickness of the secondary battery as a reference; Measuring the rate of increase in the thickness of a secondary battery over time while repeatedly charging / discharging between a first voltage higher than the full discharge voltage and the full charge voltage with respect to another secondary battery of the same model as the any one secondary battery; Change the first voltage, and then perform an operation of measuring the rate of increase in the thickness of the secondary battery over time while repeating charging / discharging between the changed first voltage and the full charge voltage at least once with respect to another secondary battery of the same model as any one of the secondary batteries; Determine a lower limit voltage from among the first voltages that has a rate greater than the reference among the measured rates of increase in the thickness of the secondary battery; and Set a protocol to repeat charging / discharging between the lower limit voltage and the full charge voltage.

9. An activation method, the activation method comprising: An operation of forming a jig with respect to an assembled secondary battery; An aging operation; And An additional charging / discharging operation, wherein the additional charging / discharging operation is performed using a charging / discharging protocol obtained by the additional charging / discharging activation protocol generation method according to claim 1 or 8.

10. An activation device, comprising: A charging / discharging device configured to perform charging / discharging with respect to an assembled secondary battery; And A control device configured to control the operation of the charging / discharging device according to a charging / discharging protocol, wherein the control device comprises: A processing unit including: a program module for running an operation (a) of measuring the rate of increase in the thickness of the secondary battery over time while repeating charging / discharging between a first voltage and a second voltage higher than the first voltage with respect to any one of the secondary batteries in the assembled secondary battery; A program module for running at least once an operation of performing operation (a) with respect to another secondary battery of the same model as any one of the secondary batteries after fixing the second voltage and changing the first voltage; A program module for determining, as a lower limit voltage, one of the first voltages other than the first voltage when showing the lowest rate among the measured rates of increase in the thickness of the secondary battery; and A program module for setting a protocol to repeat charging / discharging between the lower limit voltage and the second voltage, and After performing jig formation charging / discharging for SEI formation on the secondary battery and then having an aging time to sufficiently impregnate the electrolyte, the control device controls the charging / discharging device to perform an additional charging / discharging operation according to the protocol to form pores in the electrode active material.

11. The activation device according to claim 10, further comprising a thickness measurement unit configured to measure the thickness of the secondary battery, wherein, The control device controls the driving and measurement timing of the thickness measurement unit, and the program module of the processing unit calculates the rate of increase in the thickness of the secondary battery by using the thickness measured by the thickness measurement unit.

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