Electrode drying device and electrode drying method

Abstract

The disclosed invention provides an electrode drying device including: a heating chamber having an electrode inlet and an electrode outlet, in which an electrode is installed so as to be movable between the electrode inlet and the electrode outlet; a heating element installed in the heating chamber so as to heat the electrode in a final heating zone before the electrode outlet; and a control unit that, when the temperature of the electrode measured between the final heating zone and the electrode outlet changes depending on the operating time of the electrode drying device, variably controls the output of the heating element in response to the temperature change. The disclosed invention also provides a method for drying electrodes using the electrode drying device.

Description

[Technical Field]

[0001] The present invention relates to an electrode drying device and an electrode drying method.

[0002] Specifically, the present invention relates to an electrode drying device and an electrode drying method that variably controls the output of a heating element that heats an electrode in response to changes in the initial temperature of the electrode as it repeatedly moves and stops within a heating chamber in which the electrode is dried.

[0003] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0026101, filed on February 27, 2023, and all contents disclosed in the documents of said Korean patent application are incorporated herein by reference. [Background technology]

[0004] A secondary battery is manufactured by placing an electrode assembly in a battery case and injecting an electrolyte. The electrode assembly has a stacked structure with a separator interposed between a positive electrode and a negative electrode.

[0005] Electrodes such as positive and negative electrodes are manufactured by coating a current collector with a predetermined active material slurry. To remove moisture from the active material slurry, electrode drying is performed after the coating process. Furthermore, to remove moisture that inevitably gets mixed into the electrodes during the secondary battery manufacturing process, electrode drying may be performed in a predetermined subsequent process, such as a notching process or other various minor processes, after the coating process.

[0006] During electrode drying, the electrodes are transported roll-to-roll within a heating chamber and dried. The electrodes placed in the heating chamber are dried by a heating element placed within the heating chamber while repeatedly moving and stopping. The stopped electrodes are accelerated up to the target running speed, and once the target running speed is reached, they start running at a constant speed.

[0007] On the other hand, from the viewpoint of electrode quality stability and operational productivity, it is important to stabilize the electrode temperature in the heating chamber within a short period of time. The electrodes installed in the heating chamber are continuously discharged from the electrode outlet of the heating chamber, starting from the electrode adjacent to the electrode outlet. The electrodes pass through the final heating zone installed before the electrode outlet. Since the time it takes to pass through the final heating zone varies depending on the electrode position, the electrode temperature fluctuates at the beginning of electrode discharge. Furthermore, the electrode temperature can fluctuate depending on the number and position of heating zones in the heating chamber, and the magnitude and change of the electrode traveling speed.

[0008] A longer time for the electrode temperature to stabilize means that the quality of the electrodes produced during that time will be unstable. Since the electrodes repeatedly stop and run within the heating chamber during the operation, a longer time for the electrode temperature to stabilize will result in an increase in the production of electrodes with unstable quality. In some cases, electrodes with unstable quality will become a cause of rejection and need to be removed. This will inevitably reduce overall operational productivity.

[0009] 1 to 3 are graphs showing the principle of controlling the output of a heating member in a conventional electrode drying process.

[0010] As shown in Figure 1, in a conventional electrode drying process, in order to quickly raise the electrode temperature to the target temperature, the output of the heating element installed in the final heating zone is increased from an initial output X in response to an increase in the electrode traveling speed at the beginning of the electrode travel. The output of the heating element when the traveling speed reaches the target traveling speed is set to a constant speed output Y, and from that point onwards the electrode is heated at a constant constant speed output.

[0011] Figures 2 and 3 show the electrode temperature change due to this output change process. As shown, it takes time T1 to reach the target traveling speed, and it takes a longer equipment operating time T2 until the electrode temperature stabilizes. In other words, it takes a relatively long equipment operating time until the electrode temperature stabilizes. If the electrode temperature stabilization time can be shortened to the target time t1 in Figure 3, it can significantly improve the quality stability of the electrode and operational productivity. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Korean Patent Publication No. 10-2022-0068179 Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention has been devised to solve the above-mentioned problems, and aims to provide an electrode drying device and drying method that variably controls the output of a heating element, taking into account the condition of the electrode in the heating chamber immediately before the electrode travel and the arrangement of the heating zones. [Means for solving the problem]

[0014] An electrode drying device according to one embodiment of the present invention includes a heating chamber having an electrode inlet and an electrode outlet, in which an electrode is installed so as to be movable between the electrode inlet and the electrode outlet, a heating element installed in the heating chamber so as to heat the electrode in a final heating zone before the electrode outlet, and a control unit that, when the temperature of the electrode measured between the final heating zone and the electrode outlet changes depending on the operating time of the electrode drying device, variably controls the output of the heating element in response to the temperature change.

[0015] The electrodes may be positioned within the heating chamber such that the direction of travel of the electrodes is reversed one or more times.

[0016] The stationary electrode within the heated chamber may be accelerated at a constant rate until a target travel speed is reached.

[0017] A plurality of heating zones corresponding to the changed electrode travel directions may be arranged in the heating chamber, and the final heating zone is disposed at the rear end of the plurality of heating zones.

[0018] The control unit can correct the electrode temperature by decreasing or increasing the output of the heating element in a direction opposite to the measured electrode temperature change.

[0019] The control unit may vary the output of the heating element until the measured electrode temperature becomes constant, and after the electrode temperature becomes constant, the output of the heating element may be maintained correspondingly constant.

[0020] When the measured electrode temperature increases, the output of the heating element can be controlled in at least one of the following ways i) and ii).

[0021] i) To prevent the electrodes from overheating, the output of the heating element is reduced in proportion to the rate of rise in the electrode temperature.

[0022] ii) Decreasing the power of the heating element in proportion to the rate of increase in electrode temperature so that the electrode maintains the target temperature.

[0023] As the measured electrode temperature decreases, the power of the heating element may be increased in proportion to the rate at which the electrode temperature decreases so that the electrode temperature approaches a target temperature.

[0024] The controller may set the initial power output of the heating element to be inversely proportional to the initial electrode temperature measured between the final heating zone and the electrode outlet.

[0025] The control unit may set the initial output of the heating element to be proportional to a target travel speed of the electrode.

[0026] In another aspect of the present invention, there is provided a method for drying an electrode that starts moving from a stationary state within a heating chamber, characterized in that when the temperature of the electrode measured between a final heating zone within the heating chamber and an electrode outlet of the heating chamber changes depending on the operating time of the electrode drying apparatus, the output of a heating element disposed in the final heating zone is variably controlled in response to the temperature change.

[0027] Specifically, the electrode drying method may correct the electrode temperature at the temperature measurement point by decreasing or increasing the output of the heating element in the opposite direction to the electrode temperature change when the measured electrode temperature changes.

[0028] The electrode drying method may also vary the output of the heating element until the measured electrode temperature becomes constant, and after the electrode temperature becomes constant, maintain the output of the heating element correspondingly constant.

[0029] In the electrode drying method, the initial output of the heating element may be set to be inversely proportional to the initial electrode temperature measured between the final heating zone and the electrode outlet.

[0030] In the electrode drying method, the initial output of the heating element may be set to be proportional to a target travel speed of the electrode measured between the final heating zone and the electrode discharge port. [Effects of the Invention]

[0031] According to the present invention, the output of the heating element at the beginning of electrode travel is controlled in response to the initial temperature change of the electrode, thereby making it possible to significantly shorten the time required for the electrode temperature to stabilize.

[0032] This can significantly improve the quality stability and operational productivity of the electrode.

[0033] Furthermore, by setting the initial output of the heating element in accordance with the initial temperature of the electrode in the heating chamber and the target traveling speed of the electrode, the deviation in the time it takes for the electrode temperature to stabilize can be reduced. [Brief explanation of the drawings]

[0034] [Figure 1] 10 is a graph showing the principle of controlling the output of a heating member in a conventional electrode drying process. [Figure 2] 10 is a graph showing the principle of controlling the output of a heating member in a conventional electrode drying process. [Figure 3] 10 is a graph showing the principle of controlling the output of a heating member in a conventional electrode drying process. [Figure 4] 1 is a schematic diagram showing an example of an electrode drying device of the present invention. [Figure 5] 10 is a graph showing the change in electrode temperature over time when heated with a high-output heating element. [Figure 6] 1 is a graph showing changes in electrode temperature depending on the time to pass through the final heating zone, the operating time, and the linear speed. [Figure 7] 10 is a graph showing the change in power output of a heating element to compensate for temperature changes. [Figure 8] 4 is a graph showing an electrode temperature stabilization process according to an embodiment of the present invention. [Figure 9] 6 is a graph showing the output change and the effect of shortening the temperature stabilization time according to one embodiment of the present invention. [Figure 10] 3 is a flowchart showing an electrode drying process according to the present invention. [Figure 11] 10 is a graph showing the initial electrode temperature and the change in electrode temperature depending on the output. [Figure 12] 10 is a graph showing an initial output control principle according to another embodiment of the present invention. [Figure 13] 10 is a graph showing electrode temperature changes depending on electrode target speed and output. [Figure 14] 10 is a graph illustrating an initial output control principle according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0035] The present invention will be described in detail below. Before that, the terms and words used in the specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as meanings and concepts that are consistent with the technical idea of the present invention, based on the principle that the inventor can appropriately define the concepts of the terms in order to best describe his / her own invention.

[0036] In the present invention, the terms "comprise" and "have" are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, and may be understood as not precluding the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. Furthermore, when a part is said to be "coupled" to another part, this includes being physically coupled directly or indirectly.

[0037] In the present invention, terms such as "upper" or "lower", "front" or "rear" or "position" or "arrangement" are not limiting and may be construed as examples of words indicating position or direction.

[0038] An electrode drying device according to one embodiment of the present invention includes a heating chamber having an electrode inlet and an electrode outlet, in which an electrode is installed so as to be movable between the electrode inlet and the electrode outlet, a heating element installed in the heating chamber so as to heat the electrode in a final heating zone before the electrode outlet, and a control unit that, when the temperature of the electrode measured between the final heating zone and the electrode outlet changes depending on the operating time of the electrode drying device, variably controls the output of the heating element in response to the temperature change.

[0039] In another aspect of the present invention, there is provided a method for drying an electrode that starts moving from a stationary state within a heating chamber, characterized in that when the temperature of the electrode measured between a final heating zone within the heating chamber and an electrode outlet of the heating chamber changes depending on the operating time of the electrode drying apparatus, the output of a heating element disposed in the final heating zone is variably controlled in response to the temperature change.

[0040] The present invention will be described in detail below.

[0041] (First embodiment) During the secondary battery manufacturing process, electrode drying may be performed to remove moisture from the electrodes. As described above, it is very important to quickly stabilize the initial temperature of the electrodes during this electrode drying process in terms of operational productivity and quality stability.

[0042] The electrode drying device 100 of the present invention includes a heating chamber having an electrode inlet 11a and an electrode outlet 11b, in which an electrode 1 is placed so as to be movable between the electrode inlet 11a and the electrode outlet 11b, a heating element placed in the heating chamber so as to heat the electrode 1 in a final heating zone Z3 before the outlet, and a control unit that, when the temperature of the electrode 1 measured between the final heating zone Z3 and the electrode outlet 11b changes depending on the operating time of the electrode drying device 100, variably controls the output of the heating element 20 in response to the temperature change.

[0043] FIG. 4 is a schematic diagram showing an example of an electrode drying device 100 of the present invention.

[0044] The heating chamber 10 is a heating and drying space for the electrode 1, which houses the electrode 1, the heating member 20, and the guide roller R. FIG. 4 shows a chamber wall 11, and the interior of the chamber wall 11 forms the heating and drying space. The chamber wall 11 may also be referred to as a chamber frame. For ease of illustration, the front chamber wall 11 of the heating chamber 10 is not shown, but the chamber wall 11 is also formed on the front of the heating chamber 10, thereby forming a sealed heating and drying space. An access door (not shown) may be formed on one side of the chamber wall 11 for entering and exiting the heating chamber 10 or for performing equipment maintenance. The heating chamber 10 is formed with an electrode inlet 11a through which the electrode 1 is introduced and an electrode outlet 11b through which the dried electrode is discharged. 4, the electrode inlet 11a and the electrode outlet 11b are formed on the lower side of the heating chamber 10, but the electrode inlet 11a and the electrode outlet 11b may also be formed on the upper side of the heating chamber 10, and the positions of the electrode inlet 11a and the electrode outlet 11b are not limited thereto. However, when considering the arrangement of the heating element 20, the frame supporting the heating element 20, and the drive unit that drives the frame within the heating chamber 10, as well as the connection relationship with other devices outside the heating chamber 10, it is preferable that the electrode 1 be transported along a symmetrical running path within the heating chamber 10. Therefore, it is preferable that the electrode inlet 11a and the electrode outlet 11b be formed to be aligned opposite each other on both the upper and lower sides of the chamber wall 11 to match the symmetrical electrode running path.

[0045] The electrode 1 to be dried travels in a roll-to-roll state within the heating chamber 10. That is, the electrode 1 is transported in a roll-to-roll state along a predetermined travel path while being supported and changed in direction by a plurality of guide rollers R. In addition, predetermined unwinders and rewinders (not shown) for winding the electrode 1 are disposed outside the heating chamber 10, so that the electrode 1 can travel in a roll-to-roll state.

[0046] The heating member 20 may be a hot air blower or an infrared heater. However, it is not limited thereto as long as it is a member that can suitably heat one or both sides of the electrode 1 by a heat transfer method such as conduction, convection, or radiation. In the embodiment of the present invention, an infrared heater is used as the heating member 20. The infrared heater may include an infrared lamp 21 that irradiates the electrode 1 with infrared rays, and a support stand 22 or a mount stand that supports or mounts the infrared lamp 21.

[0047] The heating member 20 may be installed facing either the front or rear surface of the electrode 1 that is installed extending between the guide rollers R. Alternatively, a pair of heating members 20 may be installed so as to face both the front and rear surfaces of the electrode 1.

[0048] To improve the drying efficiency of the electrode 1 within a limited space, the electrode may be installed in the heating chamber 10 so that its running direction is reversed one or more times. For example, the running path of the electrode 1 may be formed so that horizontal and vertical running portions are alternately positioned within the heating chamber. In FIG. 4, three horizontal running portions and two vertical running portions are alternately arranged. However, the configuration of the running path within the heating chamber 10 is not limited thereto, and various other running path shapes may be provided within the heating chamber as long as the running path allows for efficient drying.

[0049] A plurality of guide rollers R may be disposed within the heating chamber 10 to change the direction of the electrode 1. The guide rollers R are direction-changing rollers that support the traveling electrode 1 and simultaneously change the traveling direction of the electrode 1. To increase the traveling path of the electrode 1 in a limited space such as the heating chamber 10, the electrode 1 must not travel in only one direction. In this embodiment, the guide rollers R are disposed so that the electrode 1 has an electrode traveling path that alternates between horizontal and vertical traveling sections. As a result, the electrode 1 is transported along the increased traveling path while changing direction within the limited space of the heating chamber 10, thereby improving drying efficiency. Furthermore, as the traveling path becomes longer, the space available for arranging the heating elements 20 also expands, allowing for the placement of more heating elements 20, thereby increasing the heating effect. The arrangement of the guide rollers R and the resulting electrode traveling path are not limited to the example shown in FIG. 4. The electrode traveling path may be configured along a U-shaped path, as opposed to the path shown in FIG. 4, or a path with repeated U-shaped paths.

[0050] A plurality of heating zones Z1, Z2, and Z3 may be arranged in the heating chamber in accordance with the traveling direction of the electrode. The above-mentioned heating elements 20 are installed in the heating zones Z1, Z2, and Z3 facing the electrode 1 to heat the electrode 1. As shown in FIG. 4, the heating zones Z1, Z2, and Z3 may be arranged side by side in the traveling direction of the electrode 1. In the example of FIG. 4, a first heating zone Z1 located on the electrode inlet 11a side, a third heating zone Z3 (final heating zone Z3) located on the electrode outlet 11b side, and a second heating zone Z2 located between the first heating zone Z1 and the third heating zone Z3 are arranged in the heating chamber 10. The first heating zone Z1 is installed at a position where the electrode 1 introduced into the electrode inlet 11a and traveling horizontally turns around and starts traveling vertically. The second heating zone Z2 is installed at a position where the vertically traveling electrode turns around and starts traveling horizontally. The third heating zone Z3 is located at a position where the horizontally traveling electrode 1 changes direction and starts traveling vertically again. After passing through the third heating zone Z3, the electrode 1 changes direction and continues traveling horizontally until it is discharged from the electrode discharge port 11b. Between each of the heating zones Z1, Z2, and Z3 is a non-heating section NH where no heating member 20 is placed.

[0051] The arrangement of the heating zones Z1, Z2, and Z3 is not limited to the above example, and the heating zones may be arranged in other forms depending on the size and shape of the heating chamber, the length and shape of the electrode travel path, etc. In any case, one or more heating zones are provided in the heating chamber. That is, the electrode 1 traveling in the heating chamber passes through one or more heating zones and is discharged to the electrode discharge port 11b. Therefore, the heating chamber must have at least one heating zone (e.g., the final heating zone Z3). When multiple heating zones Z1, Z2, and Z3 are installed in the heating chamber, the final heating zone Z3 is the heating zone Z3 arranged at the rear end of the multiple heating zones Z1, Z2, and Z3.

[0052] Electrodes are manufactured and processed in a continuous production line. Therefore, the electrode 1 is connected to other equipment before and after the heating chamber. The electrode 1 can repeatedly move and stop within the heating chamber depending on the start and stop of other equipment. Alternatively, the electrode 1 can repeatedly move and stop within the heating chamber according to the drying schedule of the electrode drying device 100. For example, when the unwinder and rewinder located outside the heating chamber 10 are rotated, the electrode 1 wound on them starts moving from a stopped state. The electrode 1 is accelerated from a stopped state until it reaches a target traveling speed. For example, the stopped electrode 1 can be accelerated at a constant rate until it reaches the target traveling speed. The heating element 20 in the heating chamber can also repeatedly heat and stop heating to match the electrode movement and stopping. When the drying device 100 is stopped (when the heating element 20 and the electrode traveling drive unit are stopped), the electrode 1 is stopped within the heating chamber. When the operation of the drying device 100 starts (the operation of the heating member 20 and the electrode travel drive unit starts), the electrode 1 travels and is discharged from the electrode discharge port 11b. The operating time of the electrode drying device 100 is counted from the start of the operation.

[0053] The temperature of the dried electrodes discharged from the electrode outlet 11b of the heating chamber cannot be stabilized immediately after the start of the drying device. As shown in Figures 1 to 3, the temperature can only become constant after a certain stabilization time has passed due to output control (feedback control) of the heating elements 20, particularly the heating element 20 in the final heating zone Z3. As mentioned above, the temperature stabilization time of the dried electrodes has a significant impact on operational productivity and the quality stability of the electrodes, so it is important to effectively reduce this time.

[0054] The time it takes for the electrode 1 to pass through the final heating zone Z3 and reach the electrode outlet 11b varies depending on the initial position of the electrode 1 placed in the heating chamber, which causes the temperature of the electrode 1 that has passed through the final heating zone Z3 to change continuously.

[0055] Furthermore, in the initial stage of electrode travel, the electrode travel speed changes with time, so the time it takes to pass through the final heating zone Z3 also changes depending on the initial position of the electrode, and the temperature of the electrode 1 also changes.

[0056] In addition, a predetermined non-heating section NH is located in the heating chamber according to the arrangement of the heating zones Z1, Z2, and Z3. The temperature of the electrode 1 passing through the non-heating section NH may be relatively low.

[0057] In addition, if additional heating zones Z1 and Z2 are arranged before the final heating zone Z3, the temperature of the electrode 1 that has passed through these additional heating zones Z1 and Z2 and then the final heating zone Z3 may be relatively high.

[0058] Thus, at the beginning of the electrode travel, the temperature of the electrode that has passed through the final heating zone Z3 is not constant due to various variables such as the electrode position within the heating chamber, the positions and passage times of heating zones Z1, Z2, and Z3, the travel speed, etc. Therefore, the temperature of the electrode discharged through the electrode discharge port 11b is also not constant.

[0059] The present invention is characterized in that the electrode temperature at the initial stage of electrode travel is stabilized as quickly as possible, thereby improving operational productivity and quality stability.

[0060] When the temperature of the electrode 1 measured between the final heating zone Z3 and the electrode discharge port 11b changes depending on the operating time of the electrode drying device 100, the control unit 30 of the present invention variably controls the output of the heating element 20 in response to the temperature change.

[0061] The temperature of the electrode 1 changes after passing through the final heating zone Z3, so it is necessary to accurately measure the electrode temperature at this point. Because the distance between the final heating zone Z3 and the electrode outlet 11b is short, a predetermined point within this section can be used as the temperature measurement point. Preferably, the temperature measurement point is a point immediately after the final heating zone Z3. At the temperature measurement point, the temperature of the electrode 1 is measured using a predetermined temperature measurement member S. Various types of temperature sensors can be used as the temperature measurement member S. For example, contact-type temperature sensors can be used, such as thermocouples that detect electromotive force at a specific temperature, RTDs and thermistors that detect resistance, liquid thermometers whose state changes with temperature, and bimetallic temperature sensors. However, since contact-type temperature measurements can have adverse effects on the electrode 1, it is preferable to use non-contact temperature sensors. For example, an infrared thermometer that detects temperature using infrared rays can be used as such a non-contact temperature sensor.

[0062] The temperature measuring member S can be installed at the exit of each of the heating zones Z1, Z2, and Z3. By measuring the temperature of the electrode 1 after passing through each of the heating zones Z1, Z2, and Z3 with the temperature measuring member S, the relationship between the heating of the heating member 20 and the electrode temperature can be determined.

[0063] In this embodiment, a non-contact temperature sensor (infrared thermometer) was installed at a temperature measurement point immediately after the final heating zone Z3, and the electrode temperature at that point was measured.

[0064] Since the temperature of the electrode 1 is low at the beginning of the travel of the electrode 1, the electrode 1 can be heated by the heating member 20 with a relatively high output to rapidly increase the temperature of the electrode.

[0065] In Figure 4, symbols (a), (b), (c), and (d) indicate the positions of the electrodes. Symbol (a) indicates the electrode position outside the electrode outlet, symbol (b) indicates the electrode position at the outlet of the final heating zone Z3 (more precisely, between the final heating zone and the electrode outlet), symbol (c) indicates the electrode position at the entrance of the final heating zone, and symbol (d) indicates the electrode position immediately before the second heating zone as a non-heating section.

[0066] FIG. 5 is a graph showing the change in electrode temperature according to the operating time of the electrode drying device 100 when heated by the heating element 20 at a fixed high output.

[0067] Part I of Figure 5 shows the temperature of the electrode located at electrode position (b) after the final heating zone Z3 before the electrode operating device was activated. In other words, the temperature of this electrode 1 is low because it was not heated. Therefore, the heating element 20 in the final heating zone Z3 is set to high output to achieve a rapid temperature rise.

[0068] Part II of Figure 5 shows that as the electrode continuously travels through the final heating zone Z3, the electrode temperature immediately after the final heating zone Z3 gradually increases. For example, the electrode positioned at electrode position (c) at the entrance of the final heating zone Z3 before the device started operating has the longest residence time in the final heating zone Z3 and is sufficiently heated by the high-power heating element 20, resulting in an overheated state at the point where the electrode has passed through the final heating zone Z3. In other words, the electrode temperature measured at the temperature measurement point reaches its maximum when the dryer has been in operation for XX seconds.

[0069] Part III of Figure 5 shows the electrode temperature measured at the temperature measurement point and its temperature change when the dryer operation time is ZZ seconds. This electrode 1 is located at electrode position (d) in the non-heating section NH between the final heating zone Z3 and the second heating zone Z2 before the operation of the dryer. Furthermore, when electrode 1 located in the non-heating section NH passes through the final heating zone Z3, the electrode speed increases. In this case, the passage time through the final heating zone Z3 is YY seconds, which is shorter than the XX seconds for the electrode in Part II of Figure 5. Therefore, when electrode 1 in this section reaches the temperature measurement point, the temperature has dropped from an excessive temperature rise.

[0070] Part IV of Figure 5 shows that the temperature of electrode 1 rises again. If there are no other heating zones before the final heating zone Z3, the electrode temperature will stabilize downward as the electrode travel speed increases. That is, as electrode 1 passes through the final heating zone Z3 at a fast speed, the electrode temperature measured at the temperature measurement point will decrease from an overheated state and stabilize.

[0071] However, in practice, additional heating zones such as the second heating zone Z2 are often installed in the heating chamber to improve drying productivity. In this case, even if the electrode travel speed increases, the electrode that has previously passed through the additional heating zone Z2 passes through the final heating zone Z3 and reaches the temperature measurement point. Therefore, the electrode temperature at the temperature measurement point gradually increases again due to the additional heating.

[0072] In the fifth part V of Fig. 5, the electrode travel speed reaches the target travel speed, and the travel speed and the temperature of the electrode heated in the additional heating zone Z2 and the final heating zone Z3 are in equilibrium. It is only in this part that the temperature of electrode 1 stabilizes.

[0073] As such, the temperature of electrode 1, which is continuously measured at the temperature measurement points, changes depending on the operating time of the device. The temperature change trend may vary slightly depending on the arrangement of heating zones Z1, Z2, and Z3 within the heating chamber, the time it takes to pass through the final heating zone Z3, the initial electrode temperature, etc. However, the initial temperature change of currently used electrode drying devices inevitably includes such changes. Due to these changes, it takes a considerable amount of time for the electrode temperature to stabilize.

[0074] FIG. 6 is a graph showing the change in electrode temperature depending on the time of passing through the final heating zone Z3, the operation time of the device, and the electrode traveling speed.

[0075] As in FIG. 5, the electrode temperature is lowest in the first part i of FIG. 6, which does not pass through the final heating zone Z3.

[0076] In the second part ii of FIG. 6, where the transit time through the final heating zone Z3 becomes continuously longer, the electrode temperature rises to an excessive temperature rise state.

[0077] In the third part iii of Figure 6, which shows the electrode located in the non-heated section NH passing through the final heating zone Z3, the electrode is not heated sufficiently due to the increase in the electrode travel speed, and the electrode passes through the final heating zone Z3. As a result, the electrode temperature drops.

[0078] From Part 3 (iii) onwards in Figure 6, it is shown that the electrode temperature stabilizes downward as the linear velocity increases and the target travel speed is reached. Figure 6 does not show that the electrode temperature rises again due to the heating of the additional heating zone Z2.

[0079] In the present invention, as described above, when the electrode temperature measured between the final heating zone Z3 and the electrode outlet 11b changes depending on the operating time of the electrode drying device, the output of the heating element 20 is variably controlled in response to the temperature change. When the electrode in the heating chamber is heated using a heating element 20 with a fixed output, the electrode temperature at the temperature measurement point undergoes changes of rise-fall-stabilization (when the influence of the additional heating zone Z2 is excluded) and rise-fall-rise-stabilization (when the influence of the additional heating zone Z2 is taken into account), as described above. The present invention responds to each timing of such electrode temperature changes by changing the output of the heating element 20 installed in the final heating zone Z3 from a fixed output to a variable output, thereby shortening the time until the electrode temperature finally stabilizes.

[0080] FIG. 7 is a graph showing changes in the output of the heating element 20 to compensate for temperature changes. The solid line in FIG. 7 shows the temperature change of the electrode, and the dashed line shows the change in output. As shown, the control unit 30 can decrease or increase the output of the heating element 20 in the direction opposite to the temperature change of the electrode 1. Specifically, when the electrode temperature increases in proportion to the time it takes to pass through the final heating zone Z3, the control unit 30 increases the output of the heating element 20 in proportion to the rate of increase.

[0081] Thereafter, when the electrode 1 passes through the non-heating section NH at a high traveling speed and passes through the final heating zone Z3, the temperature gradually decreases, and the output of the heating element 20 is decreased in proportion to the rate of decrease. If the additional heating zones Z1 and Z2 are not taken into consideration, the electrode temperature stabilizes downward, and the output of the heating element 20 may be controlled to stabilize upward accordingly.

[0082] In the section where the electrode temperature rises again due to heating of the additional heating zones Z1 and Z2, the output of the heating element 20 is reduced again to match the rate of the rise.

[0083] This variable output control is continued until the electrode temperature measured at the temperature measurement point becomes constant. After the electrode temperature becomes constant, the output of the heating element 20 is maintained constant accordingly. At this time, the output of the heating element 20 can be set to a constant output necessary to maintain the electrode temperature constant.

[0084] FIG. 8 is a graph showing the electrode temperature stabilization process according to one embodiment of the present invention, and FIG. 9 is a graph showing the output change and the effect of shortening the temperature stabilization time according to one embodiment of the present invention.

[0085] 8 and 9, it can be seen that the electrode temperature stabilization time is significantly reduced in the initial step of electrode travel according to the present invention.

[0086] The change in output power of the heating element 20 shown by the dashed line in FIG. 8 corresponds to, but is a simplified version of, the change in output power of the heating element 20 shown by the dashed line in FIG. 7. The initial output power P1 of the heating element 20 in FIG. 8 is set to a high power in order to quickly heat up the low-temperature electrode. Subsequently, in FIG. 7, the output power of the heating element is reduced to P2 in response to the rise in electrode temperature. By appropriately reducing the output power of the heating element, the problem of overheating of the electrode due to heating by a high-power heating element, as in the conventional technique, can be prevented. That is, in this case, the rate of reduction of the heating element output power has a slope proportional to the rate of rise in electrode temperature, and the output power can be reduced to a limit that prevents overheating of the electrode.

[0087] Next, in preparation for a drop in the electrode temperature in Fig. 7, the output of the heating element is increased to P3. This prevents the electrode temperature from dropping and brings the electrode temperature closer to the set target temperature. The rate of increase in output in this case can be suitably determined within a range that brings the electrode temperature closer to the target temperature.

[0088] Thereafter, in response to the electrode temperature rising again, the heating element output is gradually reduced to P4. In this case, the rate at which the heating element output is reduced is determined within a range in which the target temperature of electrode 1 can be maintained. That is, the rate at which the heating element output is reduced can be set so that the overall electrode temperature is maintained at the target temperature, taking into account the factor of the electrode temperature rising again due to the additional heating zones Z1 and Z2 and the factor of the electrode temperature decreasing due to the reduction in the heating element output.

[0089] Finally, during the steps where the electrode temperature is constant, the power of the heating element 20 is maintained at a correspondingly low power.

[0090] FIG. 9(a) shows only the change in output of the heating member 20 according to the operating time of the drying device of the heating member 20 in FIG.

[0091] FIG. 9(b) shows the effect of shortening the temperature stabilization time by the variable output control system of the present invention compared to the conventional traveling speed proportional control system.

[0092] As shown in Figures 8 and 9, the time required to stably achieve the target temperature is t1 (target time), which is significantly shorter than the conventional stabilization time. As an example, it was confirmed that the control according to the present invention can achieve stabilization approximately 50% faster. Since the electrode installed in the heating chamber repeatedly moves and stops, if the stabilization time is shortened as described above during a single operation of the equipment, it can be seen that the operational productivity of the present invention is significantly improved when considering the overall operation over a day, a week, or a month. Furthermore, the amount of electrode 1 produced in an unstable temperature range is significantly reduced, which can significantly improve the quality stability of the electrode.

[0093] Meanwhile, as shown in FIG. 4, the control unit 30 of the electrode drying apparatus 100 can determine whether to turn on or off the equipment or the electrode drying apparatus 100. For example, when the device is stopped before electrode travel, it can start electrode travel by transmitting an operating signal to the unwinder and rewinder drivers (e.g., motors). Furthermore, in conjunction with the start of electrode travel, it can issue a heating command to the heating elements 20 in the multiple heating zones Z1, Z2, and Z3 within the heating chamber, particularly the final heating zone Z3. For example, it can send an ON signal to the infrared lamps 21 of the heating elements 20. Furthermore, the control unit 30 can interrupt operation of the electrode drying apparatus 100 for a specific reason (such as equipment failure or completion of the required amount of electrode drying). That is, it can turn off the unwinder and rewinder drivers and send an OFF signal to the infrared lamps 21.

[0094] The control unit 30 can also adjust the electrode traveling speed by adjusting the rotation speed of the drive unit, for example, a motor. The control unit 30 can also control electrode acceleration control until the target traveling speed is reached, and whether or not the electrode travels at a constant speed after the target traveling speed. The control unit 30 can also control the output of the heating member 20. For example, if the heating member 20 is a hot air blower, the output of the heating member 20 can be adjusted by adjusting the rpm of the blower fan, adjusting the blowing air temperature, etc. If the heating member 20 is an infrared lamp 21, the output can be adjusted by controlling the amount of infrared light irradiated onto the electrode.

[0095] The present invention also provides a method for drying an electrode that starts running from a stationary state in a heated chamber.

[0096] In the electrode drying method, when the temperature of the electrode measured between the final heating zone Z3 in the heating chamber and the electrode outlet 11b of the heating chamber changes depending on the operating time of the electrode drying device 100, the output of the heating element 20 arranged in the final heating zone Z3 is variably controlled in response to the temperature change.

[0097] Specifically, when the measured electrode temperature changes, the output of the heating element 20 can be decreased or increased in the opposite direction to the electrode temperature change to correct the electrode temperature at the temperature measurement point.

[0098] For example, when the measured electrode temperature increases depending on the time it takes to pass through the final heating zone Z3, or when the electrode temperature increases as the electrode passes through an additional heating zone Z2 arranged before the final heating zone Z3 and the final heating zone Z3, the output of the heating element 20 can be controlled in at least one of the following ways i) and ii).

[0099] i) To prevent the electrodes from overheating, the output of the heating element 20 is reduced in proportion to the rate of rise in the electrode temperature.

[0100] ii) Decrease the power of the heating element 20 in proportion to the rate of increase in electrode temperature so that the electrode maintains the target temperature.

[0101] In addition, in the electrode drying method, when the measured electrode temperature decreases as the electrode passes through the non-heating section NH before the final heating zone Z3 and / or the time it takes to pass through the final heating zone Z3 becomes relatively shorter due to an increase in the electrode traveling speed, the output of the heating member 20 may be increased in proportion to the rate of decrease in the electrode temperature so that the electrode temperature approaches the target temperature.

[0102] In the electrode drying method of the present invention, the output of the heating element 20 can be changed until the measured electrode temperature becomes constant, and after the electrode temperature becomes constant, the output of the heating element 20 can be maintained constant accordingly.

[0103] FIG. 10 is a flowchart showing a method for drying an electrode according to one embodiment of the present invention.

[0104] For example, in the electrode drying device 100 of Figure 4, high power is applied at the beginning of the electrode travel, and when the electrode at the temperature measurement point experiences a temperature change as shown in Figure 7, the output of the heating element 20 in the final heating zone Z3 is changed as shown in Figure 11.

[0105] Specifically, in step S10, since the initial electrode temperature is low, a relatively high output is applied to the electrodes to achieve a rapid temperature rise.

[0106] In step S20, the output of the heating element 20 is decreased to P2 in Fig. 8 in response to the electrode temperature increase at the temperature measurement point depending on the time spent passing through the final heating zone Z3. The rate of decrease in output is basically proportional to the rate of increase in electrode temperature, but the rate of decrease in output and the end point of decrease can be suitably determined so as to prevent excessive temperature increase of the electrode at the end of the decrease.

[0107] In step S30, in response to the electrode temperature decreasing due to the electrode passing through the non-heating section NH and the electrode traveling speed increasing, the output of the heating member 20 is increased to P3 in Fig. 8. The rate of increase in output is basically proportional to the rate of decrease in the electrode temperature, but the rate of increase in output and the time point at which the increase ends can be determined so that the electrode temperature approaches the target temperature at the end of the increase.

[0108] In step S40, the output of the heating element 20 is gradually decreased to P4 in response to the electrode temperature rising again as the electrode passes through the additional heating zone Z2 and the final heating zone Z3. In this case, the rate of decrease in the output of the heating element 20 and the time at which the decrease ends are determined within a range in which the target temperature of the electrode can be maintained.

[0109] Finally, in step S50, when the electrode temperature no longer increases and remains constant, the power of the heating element 20 is maintained at a correspondingly low power.

[0110] (Second embodiment) In the electrode drying device 100 and drying method of the first embodiment, when a heating element 20 with a fixed output (e.g., high output) is used, variable output control of the heating element 20 is described to compensate for the inevitable change in the initial electrode temperature that occurs depending on the electrode position in the heating chamber and the arrangement of the heating zones Z1, Z2, and Z3. As a result, as described above, it is possible to significantly shorten the time until the temperature of the electrode adjacent to the electrode outlet 11b stabilizes.

[0111] However, deviations inevitably occur in the electrode temperature stabilization time depending on the initial electrode state before the electrode travel and the target electrode travel speed.

[0112] FIG. 11 is a graph showing the initial electrode temperature and the change in electrode temperature depending on the output.

[0113] The temperature of the electrode when the equipment or electrode drying device 100 is stopped after being temporarily stopped during continuous operation and then restarted is high due to, for example, the residual heat of the infrared lamps 21 and the temperature inside the heating chamber. Figure 11(a) shows a case where the output of the heating element 20 is controlled to be constant when the initial electrode temperatures measured at the above-mentioned temperature measurement points are different.

[0114] If the initial electrode temperature is high, excessive temperature rise occurs even when the same initial output of the heating element 20 is applied. If the initial electrode temperature is low, a delay in temperature rise occurs when the same initial output of the heating element 20 is applied. This causes a deviation in the electrode temperature stabilization time as shown in Figure 11(b).

[0115] Therefore, in order to prevent excessive temperature rise of the electrodes and delay in temperature rise time, and to reduce deviation in the electrode stabilization temperature, the control unit 30 may set the initial output of the heating element 20 to be inversely proportional to the electrode temperature.

[0116] 12(a) shows that when the initial electrode temperature is low, the initial output of the heating element 20 is high, and when the initial electrode temperature is high, the initial output of the heating element 20 is set to be inversely proportionally low. The initial electrode temperature refers to the initial temperature of the electrode measured at the temperature measurement point in the heating chamber before the start of travel. Also, the initial electrode output refers to the initial output generated by the heating element 20 at the start of travel.

[0117] Meanwhile, in this embodiment, setting the initial output inversely proportional to the initial electrode temperature does not mean that the output of the heating element 20 is variably controlled according to the operating time of the electrode drying device 100, as in the first embodiment. Setting the initial output inversely proportional to the initial electrode temperature means that the initial output is increased when the initial electrode temperature is low and decreased (proportionally) when the initial electrode temperature is high. In other words, it means that the initial output of the heating element 20 is determined taking into account the initial condition of the electrode in the heating chamber. Therefore, the output variable control after the initial output setting may be either the conventional linear velocity proportional control method or the temperature change responsive variable control method of the first embodiment. However, selecting the temperature change responsive variable control method of the first embodiment not only shortens the time it takes for the electrode temperature to stabilize, but also reduces the deviation in the temperature stabilization time, as described below.

[0118] FIG. 12(b) shows that the deviation in the electrode temperature stabilization time decreases when the output of the heating element 20 is set to be inversely proportional to the initial electrode temperature when it is high and when it is low.

[0119] (Third embodiment) Depending on the target travel speed of the electrode traveling within the heating chamber, deviations inevitably occur in the electrode temperature stabilization time.

[0120] FIG. 13 is a graph showing the electrode temperature change depending on the electrode target speed and output.

[0121] As shown in Figure 13(b), if the target electrode speed is too fast, the electrode will not be heated sufficiently, and the electrode temperature will be delayed until it reaches the electrode outlet 11b. On the other hand, if the target electrode speed is too slow, the electrode may be overheated and overheated. This causes a deviation in the electrode temperature stabilization time, as shown in Figure 13(b).

[0122] Therefore, in order to prevent excessive temperature rise of the electrodes and delay in the temperature rise time, and to reduce deviation in the electrode stabilization temperature, the control unit 30 may set the initial output of the heating member 20 to be proportional to the target traveling speed.

[0123] FIG. 14 is a graph illustrating an initial output control principle according to another embodiment of the present invention.

[0124] Referring to FIG. 14(a), it is shown that when the target traveling speed is slow, the initial output of the heating element 20 is set low, and when the target traveling speed is fast, the initial output of the heating element 20 is set high in inverse proportion thereto.

[0125] A high target travel speed means that the initial travel speed and speed acceleration rate of the electrode are high. Therefore, the electrode travels relatively fast in the initial acceleration section of the electrode. As a result, the electrode travels without being sufficiently heated, which causes a delay in the electrode temperature rise time at the temperature measurement point.

[0126] Conversely, a slow target travel speed means that the initial travel speed and speed acceleration rate of the electrode are low. Therefore, the electrode travels relatively slowly during the initial acceleration section of the electrode. This can result in excessive heating of the electrode and an overheating of the electrode at the temperature measurement point.

[0127] In the second embodiment, the variable output control after setting the initial output (first output) of the heating member 20 may be either the conventional linear velocity proportional control method or the temperature change responsive variable control method of the first embodiment. However, if the temperature change responsive variable control method of the first embodiment is selected, not only can the time taken for the electrode temperature to stabilize be shortened, but also, as will be described later, deviations in the temperature stabilization time can be reduced.

[0128] FIG. 14(b) shows that the deviation in the electrode temperature stabilization time is reduced when the output of the heating element 20 is set to be proportional to the target electrode traveling speed when it is fast and when it is slow.

[0129] As described above, according to the present invention, the time required for the electrode temperature to stabilize can be significantly reduced, thereby significantly improving the operational productivity of the electrode drying process and the quality stability of the electrode.

[0130] Furthermore, according to one embodiment of the present invention, the deviation in the electrode temperature stabilization time can be reduced by setting the initial output of the heating element 20, specifically the heating element 20 in the final heating zone Z3, in accordance with the initial temperature of the electrode and the target running speed.

[0131] The electrode drying device 100 and electrode drying method of the present invention can be applied to all processes in which electrodes are dried, including the drying process after electrode coating and subsequent processes up to the time when the electrodes are housed in a battery case.

[0132] The above description is merely an illustrative example of the technical concept of the present invention, and various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains without departing from the essential characteristics of the present invention.

[0133] Therefore, the drawings disclosed in the present invention are for explanation purposes only, not for limiting the technical idea of the present invention, and the scope of the technical idea of the present invention is not limited by such drawings. The scope of protection of the present invention should be interpreted by the claims, and all technical ideas within the equivalent range should be interpreted as being included in the scope of the present invention. [Explanation of symbols]

[0134] 1: Electrode 10: Heating chamber 11: Chamber wall (chamber frame) 11a: Electrode inlet 11b: Electrode outlet 20: Heating element 21: Infrared lamp 22: Support stand (mounting stand) 30: Control unit R: Guide roller First heating zone: Z1 Second heating zone: Z2 Third heating zone (final heating zone): Z3 Unheated section: NH S: Temperature measurement component (temperature sensor)

Claims

1. a heating chamber having an electrode inlet and an electrode outlet, in which an electrode is installed so as to be movable between the electrode inlet and the electrode outlet; a heating element disposed within the heating chamber to heat the electrode in a final heating zone before the electrode outlet; a control unit that, when the temperature of the electrode measured between the final heating zone and the electrode discharge port changes depending on the operating time of the electrode drying device, variably controls the output of the heating element in response to the temperature change.

2. The electrode drying apparatus according to claim 1 , wherein the electrode is placed in the heating chamber so that the traveling direction of the electrode is reversed one or more times.

3. 2. The electrode drying apparatus according to claim 1, wherein the stationary electrode within the heating chamber is accelerated at a constant rate until it reaches a target travel speed.

4. A plurality of heating zones are arranged in the heating chamber, each corresponding to a different electrode travel direction; The electrode drying apparatus according to claim 2 , wherein the final heating zone is disposed at the rearmost end of the plurality of heating zones.

5. The electrode drying device according to claim 1 , wherein the control unit corrects the electrode temperature by decreasing or increasing the output of the heating element in a direction opposite to the measured electrode temperature change.

6. the control unit changes the output of the heating element until the measured electrode temperature becomes constant; 6. The electrode drying device according to claim 5, wherein after the temperature of the electrode becomes constant, the output of the heating element is maintained correspondingly constant.

7. When the measured electrode temperature increases, the output of the heating element is controlled by at least one of the following methods i) and ii): i) reducing the output of the heating element in proportion to the rate of rise in electrode temperature so as to prevent the electrode from overheating; ii) decreasing the power of the heating element in proportion to the rate of increase in electrode temperature so that the electrode maintains the target temperature; The electrode drying device according to claim 5 .

8. 6. The electrode drying device according to claim 5, wherein when the measured electrode temperature decreases, the output of the heating element is increased in proportion to the rate of decrease in the electrode temperature so that the electrode temperature approaches a target temperature.

9. The electrode drying device according to claim 1 , wherein the control unit sets the initial output of the heating element so as to be inversely proportional to an initial electrode temperature measured between the final heating zone and the electrode outlet.

10. The electrode drying device according to claim 1 , wherein the control unit sets the initial output of the heating member so as to be proportional to a target traveling speed of the electrode.

11. 1. A method for drying an electrode that starts running from a stationary state in a heated chamber, comprising: An electrode drying method in which, when the temperature of the electrode measured between the final heating zone in the heating chamber and the electrode outlet of the heating chamber changes depending on the operating time of an electrode drying device equipped with the heating chamber, the output of a heating element arranged in the final heating zone is variably controlled in response to the temperature change.

12. 12. The electrode drying method according to claim 11, wherein when the measured electrode temperature changes, the output of the heating element is decreased or increased in a direction opposite to the change in the electrode temperature, thereby correcting the electrode temperature at the temperature measurement point.

13. Varying the power output of the heating element until the measured electrode temperature remains constant; 13. The electrode drying method according to claim 12, wherein after the temperature of the electrode becomes constant, the output of the heating element is maintained constant in accordance with the temperature of the electrode.

14. 12. The method for drying an electrode according to claim 11, wherein the initial power output of the heating element is set inversely proportional to the initial electrode temperature measured between the final heating zone and the electrode outlet.

15. 12. The electrode drying method according to claim 11, wherein the initial output of the heating element is set to be proportional to a target travel speed of the electrode measured between the final heating zone and the electrode discharge port.

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