Electrode rolling method

Abstract

The electrode rolling method of the present invention includes the steps of (A) setting rolling conditions for the electrode, and (B) rolling the electrode under the rolling conditions. The rolling conditions are conditions for realizing the electrode to a target thickness, and include the gap between a pair of rolling rolls, the back pressure on the rolling rolls, and the target load. The target electrode thickness is realized by adjusting the rolling conditions according to the load measured in step (B).

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0183575 filed December 23, 2022 and Korean Patent Application No. 10-2023-0027509 filed March 2, 2023, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to an electrode rolling method, and more particularly to an electrode rolling method that can continuously and consistently achieve a desired electrode thickness in response to a load measured during electrode rolling. [Background technology]

[0003] A secondary battery can be formed by inserting an electrode assembly consisting of a positive electrode plate, a negative electrode plate, and a separator into a case and then sealing it. The positive electrode plate or the negative electrode plate (hereinafter referred to as "electrode plate") can be formed by coating a positive electrode conductive current collector or a negative electrode conductive current collector with a certain thickness of active material slurry, interposing a separator between the positive electrode conductive current collector and the negative electrode conductive current collector, and winding the coated electrode plate into a jelly roll shape or stacking the coated electrode plate into multiple layers.

[0004] The manufacturing process of a secondary battery mainly includes an electrode process, which can be divided into an active material mixing process, an active material coating process, a rolling process, a slitting process, a winding process, etc. More specifically, the electrode plate may include a coated portion coated with the active material slurry and an uncoated portion not coated with the active material slurry. A rolling process may be included in which the electrode plate is rolled to improve adhesion between the coated active material slurry and the electrode current collector and increase the active material capacity density. After drying, the rolled electrode plate is passed through a cutter with a predetermined width and cut to a predetermined size for use.

[0005] 1 to 3 are conceptual diagrams showing a rolling device for explaining the electrode rolling process.

[0006] Referring to FIG. 1, a rolling apparatus for rolling electrodes includes a pair of rolls 20 and 30.

[0007] The electrode 10 is reduced in thickness as it passes between a pair of rolling rolls.

[0008] As shown in Figure 2, when rolling is performed to produce a high-density electrode 10, the force (linear pressure) that causes the electrode 10 to spread apart the two rolls 20 and 30 increases, resulting in roll bending. An electrode 10 produced in this state where the rolls 20 and 30 are bent is thicker at the center than at both ends, resulting in poor quality. To address this thickness deviation during the rolling process, back pressure is applied to both ends of the rolls 20 and 30 to suppress bending, as shown in Figure 3. Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide an electrode rolling method that can continuously and consistently achieve a desired electrode thickness in an electrode rolling process according to a load measured during electrode rolling.

[0010] However, the problems to be solved by the embodiments of the present invention are not limited to the above-mentioned problems, and can be expanded in various ways within the scope of the technical ideas included in the present invention. [Means for solving the problem]

[0011] The electrode rolling method of the present invention includes the steps of (A) setting rolling conditions for the electrode, and (B) rolling the electrode under the rolling conditions. The rolling conditions are conditions for achieving a target thickness of the electrode, and include the gap between a pair of rolling rolls, the back pressure on the rolling rolls, and the target load. The target thickness of the electrode can be achieved by adjusting the rolling conditions in accordance with the load measured in step (B).

[0012] The method may further include the steps of (C) comparing the load measured in the rolling step with the target load, and (D) continuing to roll the subsequent electrode under the rolling conditions when the difference between the target load and the measured load is not outside the predetermined range.

[0013] Step (C) is performed according to the following formula 1: |(P target )-(P measure )|≦A (Equation 1) In the formula, P target is the target load, P measure is the measured load, and A may be any value selected from positive real numbers as the predetermined value.

[0014] The method may further include a step (E) of adjusting the gap of the rolling rolls by a predetermined amount when the difference between the target load and the measured load is outside a predetermined range, and after step (E), steps (B) and (C) may be performed for the subsequent electrode with the adjusted gap of the rolling rolls.

[0015] Step (E) and steps (B) and (C) subsequent to step (E) may be repeated until the difference between the target load and the measured load falls within a predetermined range.

[0016] In step (D), the predetermined range may be an error tolerance range of the target load.

[0017] (F) When there is a change in the back pressure, the method further includes a step of adjusting the gap of the rolling rolls, and the adjusted gap of the rolling rolls allows steps (B) and (C) to be performed on the subsequent electrode.

[0018] The change in counter pressure may be automatic or manual.

[0019] In step (B), when the speed of movement of the electrode is maintained for a predetermined time, the load on the electrode can be measured.

[0020] The rolling conditions when the electrode reaches the target thickness may be automatically stored in the data storage unit.

[0021] When the electrode is subjected to a first rolling and then a second rolling, the electrode rolling method can be applied to at least one of the first rolling and the second rolling. [Effects of the Invention]

[0022] According to the electrode rolling method of the present invention, a desired electrode thickness can be continuously and consistently achieved in accordance with the load measured during electrode rolling.

[0023] Furthermore, during electrode rolling, the desired thickness can be achieved by performing electrode rolling according to the present invention in parallel with thickness measurement, and in some cases, the desired thickness can be achieved by performing electrode rolling according to the present invention even without thickness measurement.

[0024] Therefore, the production efficiency of the electrode assembly can be maximized, productivity can be improved, and the manufacturing cost can be reduced, while the quality of the produced electrode assemblies can also be improved.

[0025] The effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 2 is a conceptual diagram showing a rolling device for explaining an electrode rolling step. [Figure 2] FIG. 2 is a conceptual diagram showing a rolling device for explaining an electrode rolling step. [Figure 3] FIG. 2 is a conceptual diagram showing a rolling device for explaining an electrode rolling step. [Figure 4] 2 shows a flow chart of an electrode rolling method according to one embodiment of the present invention. [Figure 5] 5 shows a flowchart for the electrode rolling method according to FIG. 4 when the back pressure is changed. [Figure 6] 1 is a schematic diagram showing an electrode rolling system (apparatus) for implementing an electrode rolling method according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027]

[0023] Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention can be embodied in several different forms and is not limited to the embodiments described herein.

[0028] For clarity of description of the present invention, parts that are not relevant to the description will be omitted and the same reference numerals will be used throughout the specification to refer to the same or similar components.

[0029] Furthermore, the size and thickness of each component shown in the drawings are arbitrarily shown for the convenience of explanation, and the present invention is not necessarily limited to those shown. In the drawings, thicknesses are exaggerated to clearly show multiple layers and regions. In addition, in the drawings, thicknesses of some layers and regions are exaggerated for the convenience of explanation.

[0030] An electrode rolling method according to one embodiment of the present invention will be described below with reference to FIGS.

[0031] FIG. 4 shows a flowchart of an electrode rolling method according to one embodiment of the present invention.

[0032] In the electrode rolling method according to Fig. 4, first, step S110 is performed to set rolling conditions for the electrode. The rolling conditions are conditions for achieving a target thickness of the electrode 10, and include the gap between the pair of rolls 20, 30, the back pressure on the rolls 20, 30, and the target load. The rolling conditions may be directly input to the input / output unit 150 of the rolling mill 100 (see Fig. 6) that executes the electrode rolling method, or data on the rolling conditions stored in advance in the data storage unit 140 may be applied.

[0033] Subsequently, step S120 is performed in which the electrode 10 is rolled by the rolls 20 and 30.

[0034] At the beginning of the process, step S120 is performed under the rolling conditions in step S110. That is, the electrode 10 is rolled under the gap between the rolls 20, 30 and the back pressure on the rolls 20, 30 set in step S110. On the other hand, as will be described later, if the rolling conditions are adjusted during the rolling process, step S120 is performed under the adjusted rolling conditions. This will be described in detail in step S150 below.

[0035] In step S120, the actual load on the rolls 20 and 30 during rolling of the electrode 10 is measured. This is because even if the target load is set in step S110, rolling may not be performed accurately due to various circumstances in the actual rolling process, and errors may occur. In addition, as will be described later, the rolling conditions are adjusted according to the load measured in step S120 so that the target thickness of the electrode 10 can be achieved.

[0036] The rolls 20 and 30 may be at least a pair of opposing rolls used in a typical electrode rolling process. The actual loads of the rolls 20 and 30 are measured by a load cell (not shown). For example, when the moving speed of the electrode 10 is maintained for a predetermined time, step S120 may determine that the electrode 10 is in a normal operating state, and the actual loads of the rolls 20 and 30 may be measured. Alternatively, for example, the actual loads of the rolls 20 and 30 may be measured continuously in real time while step S120 is being performed.

[0037] Next, step S130 is performed to compare the load measured during rolling with the target load. The load measured during rolling refers to the actual load measured in step S120. The target load refers to the target load set in step S110, which is the load for achieving the target thickness of the electrode 10. In step S130, for example, the difference between the measured load and the target load is calculated, and it is determined whether the difference falls within a predetermined range (for example, an error tolerance range). For example, the following equation 1 can be applied.

[0038] |(P target )-(P measure )|≦A (Equation 1)

[0039] In the formula, P target is the target load, P measure is the measured load, and A is a predetermined value (any value selected from positive real numbers). A may be selected for various process environments and / or electrode types, or may be predetermined. For example, A may be a predetermined error tolerance for various process environments and / or electrode types.

[0040] Next, if the comparison in step S130 shows that the difference between the target load and the measured load is not outside the predetermined range, step S140 is performed to continue rolling the subsequent electrode under the rolling conditions that have already been set.

[0041] When the actual load measured during rolling of the electrode 10 in step S120 is within a predetermined range (e.g., an allowable error range) based on the target load, it can be determined that the rolling of the electrode 10 in step S120 is being performed with the target load. In other words, it can be determined that the electrode 10 has been rolled to the target thickness. Based on this, the electrode 10 that subsequently enters the work rolls 20 and 30 can also be continuously rolled under the already set rolling conditions (e.g., the gap between the work rolls 20 and 30, the back pressure on the work rolls 20 and 30).

[0042] However, if the result of the comparison in step S130 shows that the difference between the target load and the measured load is outside the predetermined range, step S150 is performed to adjust the gap between the rolls by a predetermined amount.

[0043] If the actual load measured during rolling of the electrode 10 in step S120 is not within a predetermined range (for example, an allowable error range) based on the target load, it is determined that the rolling of the electrode 10 in step S120 is not performed with the target load. In other words, it is determined that the electrode 10 has not been rolled to the target thickness. Based on this, the gap between the rolls 20 and 30 is adjusted so that the target thickness can be achieved for the electrode 10 that subsequently enters the rolls 20 and 30.

[0044] In step S150, the gap between the work rolls 20, 30 is adjusted by a predetermined amount for a predetermined period of time. Thereafter, steps S120 and S130 are performed for the electrode 10 that follows the work rolls 20, 30. That is, steps S120 and S130 are performed under the adjusted rolling conditions (adjusted work roll gap). At this time, in step S120, as described above, the actual loads of the work rolls 20, 30 that roll the electrode 10 under the adjusted rolling conditions (adjusted work roll gap) are measured. Also, in step S130, the load measured during rolling under the adjusted rolling conditions is compared with the target load.

[0045] Subsequently, as a result of the comparison in step S130, if the difference between the target load and the measured load (i.e., the load during rolling under the adjusted rolling conditions) is not outside the predetermined range, then in step S140, rolling is continued under the adjusted rolling conditions for the subsequent electrode, as described above. That is, if a load within the error tolerance of the target load is measured under the adjusted rolling conditions (adjusted gap between the mill rolls), rolling of the electrode 10 can be continued in the same manner as in step S140.

[0046] However, if the comparison in step S130 shows that the difference between the target load and the measured load is outside the predetermined range, then in step S150, the rolling conditions (gap of the rolls) are readjusted by a predetermined amount, as described above. That is, if a load within the allowable error range of the target load is not measured under the adjusted rolling conditions (adjusted gap of the rolls), the rolling conditions (gap of the rolls) are adjusted again through step S150. By repeating steps (S150, S120, S130) in this manner, a load within the allowable error range of the target load is measured during rolling of the electrode 10 under the adjusted rolling conditions (adjusted gap of the rolls), and rolling of the electrode 10 can be continued as in step S140.

[0047] On the other hand, if rolling of the electrode 10 is continued in step S140, the desired thickness (target thickness) of the electrode 10 may not be achieved or the thickness of the electrode 10 may become uneven due to various reasons related to the process environment. In some cases, it may be necessary to change the back pressure of the rolling rolls 20 and 30 so that the electrode 10 can be rolled normally and uniformly to the target thickness.

[0048] When such a change in the back pressure is required, step S160 of adjusting the gap between the rolls is additionally performed. In relation to this, Fig. 5 shows a flowchart for the case where the back pressure is changed in the electrode rolling method according to Fig. 4.

[0049] First, the change in the back pressure may be automatic or manual. Automatic change means that when the process environment or the like changes, the back pressure applied to the rolls 20, 30 is changed according to an algorithm (program) preset for the process. Manual change means that when a worker in the process sets a back pressure value and inputs it into the input / output unit 150, the back pressure applied to the rolls 20, 30 is changed according to the back pressure value input into the input / output unit 150.

[0050] Furthermore, when the back pressure applied to the rolls 20, 30 is changed, the load applied to the electrode 10 by the rolls 20, 30 also changes. This is because the load is calculated as the product of pressure and area, and the back pressure is a pressure applied in the opposite direction to the linear pressure, which is the pressure applied to the electrode by the rolls 20, 30. On the other hand, since the load applied to the electrode 10 by the rolls 20, 30 is changed, it is necessary to adjust the load applied to the electrode 10 so that it becomes the target load again.

[0051] Therefore, if there is such a change in the back pressure, step S160 of adjusting the gap between the rolls is additionally performed. With the adjusted gap between the rolls, step S120 and subsequently step S130 are performed as described above.

[0052] Similarly, if the comparison in step S130 shows that the difference between the target load and the measured load (i.e., the load during rolling under the adjusted rolling conditions) is not outside the predetermined range, then in step S140, rolling is continued under the adjusted rolling conditions for the subsequent electrode, as described above.

[0053] However, if the comparison in step S130 shows that the difference between the target load and the measured load is outside the predetermined range, the rolling conditions (gap of the mill rolls) are readjusted by a predetermined amount in step S150, as described above. Steps (S150, S120, S130) are repeated until a load within the error tolerance of the target load is measured during rolling of the electrode 10 under the adjusted rolling conditions (adjusted gap of the mill rolls).

[0054] The above-described embodiment of the present invention can be particularly effectively applied to a process in which a thickness measurement device for the electrode 10 is not provided during rolling of the electrode 10. Alternatively, the thickness of the electrode 10 to be rolled can be manufactured to a desired thickness (target thickness) without measuring the thickness of the electrode 10 each time. This is because the rolls 20 and 30 roll the electrode 10 with a target load for achieving the target thickness of the electrode 10. Of course, the present invention is not limited to this, and can be applied in parallel with the thickness measurement device when a thickness measurement device is provided, thereby more efficiently achieving the desired thickness (target thickness) of the electrode 10.

[0055] The above-described embodiments of the present invention can be applied, for example, to a process for manufacturing a negative electrode. In some cases, a phenomenon (springback) in which the rolled electrode expands again after primary rolling may occur in the case of a negative electrode. Therefore, secondary rolling is performed after the primary rolling when manufacturing a negative electrode. The above-described embodiments of the present invention can be applied, for example, to primary rolling. This is because it is easy to achieve the desired primary rolling thickness of the electrode using the target load of the rolls 20 and 30 without measuring the thickness of the electrode 10. In other words, it is only necessary to measure the thickness of the electrode finally manufactured by secondary rolling after the primary rolling. However, the present invention is not limited thereto and can also be applied to the secondary rolling of an electrode (negative electrode). Various modifications and variations are possible, such as applying the embodiments of the present invention to a process for manufacturing a positive electrode that can be manufactured sufficiently by primary rolling.

[0056] FIG. 6 schematically shows an electrode rolling system (apparatus) for implementing an electrode rolling method according to one embodiment of the present invention.

[0057] The electrode rolling method according to the embodiment of the present invention may be realized by an electrode rolling system 100 including a rolling unit 110, a transceiver 120, and a controller 130, as shown in FIG.

[0058] A rolling device commonly used in electrode manufacturing processes can be used as the rolling unit 110, and therefore a detailed illustration is omitted. The rolling unit 110 can include the rolls 20 and 30, a counter pressure cylinder (not shown), various sensors (not shown), etc. shown in FIG. 1. The sensors can include a sensor that measures the gap between the rolls 20 and 30, a load cell that measures the load on the rolls 20 and 30, etc., and can additionally include a temperature sensor that measures the temperature of the rolls 20 and 30, a speed sensor that measures the moving speed of the electrode or the driving speed of the rolls, etc.

[0059] The transceiver 120 receives data transmitted from sensors provided in the rolling unit 110 or data transmitted from the operator's input / output unit 150, and transmits this data to the controller 130. As described above, the data transmitted to the controller 130 includes the gap and / or back pressure change amount (or back pressure) of the rolling rolls, and in some cases may further include the rolling temperature, rolling speed, etc.

[0060] The controller 130 receives data such as the measured actual load, compares it with the target load, and determines whether to perform step S140 or step S150 as the subsequent step. The controller 130 may be connected to a data storage unit 140 that is integrated into the electrode rolling system 100 or is provided externally.

[0061] When performing the electrode rolling method according to an embodiment of the present invention, if the target load is achieved, data related to the rolling conditions at that time (roll gap, back pressure, rolling temperature, rolling speed, electrode movement speed, etc.) may be stored in the data storage unit 140.

[0062] Regarding the components related to other devices necessary to realize the electrode rolling method according to the embodiment of the present invention, reference is made to devices used in a typical electrode rolling process.

[0063] According to the electrode rolling method of the present invention, the target thickness of the electrode 10 can be achieved as a target load according to process conditions without the need for thickness measurement of the electrode 10 or intervention by an operator. That is, the desired thickness after rolling can be consistently achieved and maintained without the operator having to go through a process of checking the thickness each time. Furthermore, when used in parallel with thickness measurement, the desired thickness after rolling can be consistently achieved and maintained more effectively.

[0064] Therefore, the efficiency of the electrode manufacturing process is maximized, productivity is improved, and manufacturing costs can be reduced.

[0065] At the same time, according to the electrode rolling method according to an embodiment of the present invention, the thickness of the rolled electrodes can be made uniform, which makes it possible to uniformize and improve the quality of secondary batteries including the manufactured electrodes, and significantly reduces the defective rate.

[0066] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to these, and various modifications and alterations made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention. [Explanation of symbols]

[0067] 10 electrodes 20, 30 Rolling mill 100 Electrode Rolling System 110 Rolling Unit 120 Transmitter / Receiver 130 Controller 140 Data Storage Unit 150 Input / Output Unit

Claims

1. An electrode rolling method, comprising: (A) setting rolling conditions for the electrode; (B) rolling the electrode under the rolling conditions, the rolling conditions are conditions for achieving a target thickness of the electrode, and include a gap between a pair of rolling rolls, a back pressure on the rolling rolls, and a target load; an electrode rolling method, wherein the target thickness of the electrode is achieved by adjusting the rolling conditions in accordance with the load measured in step (B).

2. (C) comparing the load measured in the rolling step with the target load; 2. The electrode rolling method according to claim 1, further comprising: (D) a step of continuously performing rolling on a subsequent electrode under the rolling conditions when the difference between the target load and the measured load is not outside a predetermined range.

3. The step (C) is carried out in accordance with the following formula 1: | (P ｔａｒｇｅｔ ) - (P ｍｅａｓｕｒｅ )|≦A (Formula 1) In the formula, P ｔａｒｇｅｔ is the target load, P ｍｅａｓｕｒｅ The electrode rolling method according to claim 2, wherein A is the measured load, and A is a predetermined value selected from positive real numbers.

4. (E) adjusting the gap of the rolls by a predetermined amount when the difference between the target load and the measured load is outside a predetermined range; 4. The electrode rolling method according to claim 2, wherein after step (E), steps (B) and (C) are performed for a subsequent electrode with the gap between the rolls adjusted.

5. 5. The electrode rolling method according to claim 4, wherein the step (E) and the steps (B) and (C) subsequent to the step (E) are repeatedly performed until a difference between the target load and the measured load falls within a predetermined range.

6. 3. The electrode rolling method according to claim 2, wherein in step (D), the predetermined range is an allowable error range of the target load.

7. (F) adjusting the gap between the rolls when there is a change in back pressure; 7. The electrode rolling method according to claim 2, wherein the step (B) and the step (C) are performed for a subsequent electrode with the adjusted gap between the rolling rolls.

8. The electrode rolling method according to claim 7 , wherein the change in the back pressure is an automatic change or a manual change.

9. 7. The electrode rolling method according to claim 1, wherein in step (B), a load on the electrode is measured while the moving speed of the electrode is maintained for a predetermined time.

10. 7. The electrode rolling method according to claim 1, wherein the rolling conditions when the electrode reaches the target thickness are automatically stored in a data storage unit.

11. 7. The electrode rolling method according to claim 1, wherein when a first rolling is performed on the electrode and then a second rolling is performed, the electrode rolling method is applicable to at least one of the first rolling and the second rolling.

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