Electrode drying device

Abstract

According to an embodiment of the present invention, there is provided an electrode drying apparatus, comprising: an intake fan configured to supply air through an intake duct to a drying space in which an electrode having a coating liquid applied thereto on a current collector is dried; an exhaust fan configured to exhaust air from the drying space through an exhaust duct; a return duct configured to supply air exhausted from the exhaust fan to the intake fan; a return damper configured to adjust the amount of air flowing into the return duct; a main hygrometer configured to sense the absolute humidity of the air supplied to the drying space; and a control unit configured to adjust the opening degree of the return damper according to the absolute humidity sensed by the main hygrometer in order to adjust the absolute humidity of the air flowing into the drying space.

Description

【Technical Field】 【0001】 The present invention relates to an electrode drying device and an electrode drying method using the same, and more particularly, to an electrode drying device and a drying method capable of performing uniform drying and preventing cracks from occurring in a coated active material. 【Background Art】 【0002】 Batteries for storing electrical energy can generally be classified into primary batteries and secondary batteries. A primary battery is a disposable consumable battery, while a secondary battery is a rechargeable battery manufactured using a material in which the oxidation and reduction processes between current and substances can be repeated. That is, when a reduction reaction is performed on the material by current, the power source is charged, and when an oxidation reaction is performed on the material, the power source is discharged, and such charging and discharging can be repeated. 【0003】 Among various types of secondary batteries, a lithium secondary battery can be manufactured through a process of coating a negative electrode slurry in which a negative electrode active material, a conductive material, a binder, and a solvent are mixed on a current collector and drying it to manufacture a negative electrode. 【0004】 Conventionally, a coating layer coated with a negative electrode slurry has been put into a general oven for drying. However, as shown in FIGS. 1 and 2, due to the flow of liquid, a sliding section in the form of a slope occurs on the side surface, so that the drying speed becomes faster as it goes to the side surface B where the loading amount of the negative electrode slurry is relatively small with respect to the center portion A of the coating layer, resulting in a drying deviation in the width direction C of the electrode due to over-drying, and thus a problem that cracks D occur on the electrode surface has occurred. 【0005】 In order to improve such surface crack problems and side ringing on the side surface due to over-drying, conventionally, various efforts such as varying the amount of heat added to the drying space depending on the position have been tried. 【0006】 However, even with heat adjustments during the drying process, surface cracking problems and other issues were not significantly improved, and the drying process required more time, making it difficult to carry out an efficient and stable drying process. 【0007】 Therefore, there is a need for an electrode drying apparatus and method that can perform efficient and stable electrode drying to solve these problems. [Overview of the project] [Problems that the invention aims to solve] 【0008】 The present invention aims to solve the problems of conventional electrode drying apparatuses and drying methods. 【0009】 One embodiment of the present invention provides an apparatus and method that can effectively and efficiently dry electrodes while utilizing conventional electrode drying apparatuses and methods without significant modifications. 【0010】 One embodiment of the present invention provides an apparatus and method that can effectively prevent crack formation and side ring formation on the electrode surface by reducing drying deviation in the width direction. 【0011】 According to one embodiment of the present invention, the aim is to provide a drying apparatus and method that can easily and effectively provide the required absolute humidity environment in stages by utilizing multiple hygrometers and dampers. [Means for solving the problem] 【0012】 To achieve the aforementioned objectives, according to one embodiment of the present invention, an electrode drying apparatus may be provided which includes: an air supply fan provided to supply air through an air supply duct to a drying space where an electrode coated with a coating liquid on a current collector is dried; an exhaust fan provided to exhaust air from the drying space through an exhaust duct; a recovery duct that supplies the air discharged from the exhaust fan to the air supply fan; a recovery damper that adjusts the amount of air flowing into the recovery duct; a main hygrometer that senses the absolute humidity of the air supplied to the drying space; and a control unit that adjusts the opening of the recovery damper based on the absolute humidity sensed by the main hygrometer in order to adjust the absolute humidity of the air flowing into the drying space. 【0013】 In the initial stages of the drying process, most of the heat is used to heat the drying space and electrodes, while in the later stages, most of the heat may be used to evaporate the solvent. Therefore, the absolute humidity of the air discharged from the drying space is low in the initial stages of the drying process, and high in the later stages. 【0014】 This embodiment is characterized by performing drying in a constant absolute humidity environment. Furthermore, the required amount of absolute humidity is obtained by utilizing the humidity discharged from the drying space. 【0015】 Therefore, according to this embodiment, the opening ratio of the recovery damper is low in the early stages of the drying process, and the opening ratio of the recovery damper can increase as the drying process progresses to the middle and later stages. 【0016】 The exhaust duct may include a first exhaust duct connecting the drying space and the exhaust fan, and a second exhaust duct connecting the exhaust fan and an external exhaust port. 【0017】 The air supply duct may include a first air supply duct connecting an external air intake port to the air supply fan, and a second air supply duct connecting the air supply fan to the drying space. 【0018】 The recovery duct is preferably branched from the second exhaust duct and connected to the first air supply duct. 【0019】 The second exhaust duct is preferably provided with an exhaust damper for adjusting the amount of air exhausted to the external exhaust port. And the exhaust damper is preferably provided at the rear end of the branch point of the recovery duct. 【0020】 The recovery duct is preferably provided with a recovery hygrometer for sensing the absolute humidity of the air flowing into the first air supply duct through the recovery duct. 【0021】 The control unit preferably adjusts the opening degree of the recovery damper according to the absolute humidity sensed by the recovery hygrometer. 【0022】 The control unit preferably adjusts the opening degree of the exhaust damper to decrease as the opening degree of the recovery damper increases. 【0023】 The first air supply duct is preferably provided with an air supply damper for adjusting the amount of air flowing in from the external air supply port. 【0024】 The air supply damper is preferably provided at the front end of the confluence point of the recovery duct. 【0025】 The first air supply duct is preferably provided with an air supply hygrometer for sensing the absolute humidity of the air flowing in from the recovery duct and the external air supply port. 【0026】 The control unit preferably adjusts the opening degrees of the recovery damper and the air supply damper according to the absolute humidity sensed by the air supply hygrometer. 【0027】 In the initial stage of drying, the absolute humidity of the external air may be higher than that of the recovered air. Therefore, in the initial stage of drying, it is preferable to adjust the opening degree of the damper based on the absolute humidity sensed by the supply air hygrometer. In particular, it can be controlled such that the opening rate of the supply air damper is higher than that of the recovery damper, and as a result, the absolute humidity sensed by the main hygrometer can be increased. It is preferable to control the opening rate of the standby damper to decrease conversely as the opening rate of the recovery damper increases. 【0028】 After the middle stage of drying, the absolute humidity of the recovered air may be higher than that of the external air. Therefore, after the middle stage of drying, it is preferable to adjust the opening degree of the damper based on the absolute humidity sensed by the recovery hygrometer. In particular, it can be controlled such that the opening rate of the recovery damper is higher than that of the supply air damper, and as a result, the absolute humidity sensed by the main hygrometer can be increased. It is preferable to control the opening rate of the standby damper to decrease conversely as the opening rate of the recovery damper increases. 【0029】 Overdrying can occur intensively after the middle stage of drying, particularly at the end of drying. Therefore, it is preferable to appropriately maintain the absolute humidity at the end of drying. Therefore, in the final stage of drying, it is preferable to adjust the opening degree of the damper based on the absolute humidity sensed by the main hygrometer. In particular, it is preferable to control the opening rate of the recovery damper to be higher than that of the supply air damper, and to control the drying to be completed in an optimal absolute humidity environment. 【0030】 A humidifier may be provided in the recovery duct. When the coating thickness of the active material is thick, that is, in the case of an electrode with a large loading amount, the required absolute humidity may be even higher. In this case, it may be difficult to create a sufficient absolute humidity environment only by recovering moisture. That is, it may be difficult to create a sufficient absolute humidity environment even when the recovery damper is fully opened and the exhaust damper and the supply air damper are completely closed. In this case, a humidifier may be provided and driven for additional humidification of the recovered air. That is, the control unit can additionally drive the humidifier based on the absolute humidity sensed by the main hygrometer. 【0031】 Preferably, the control unit controls the system so that humidification is performed through the humidifier when the absolute humidity sensed by the main hygrometer is lower than a previously set value. 【0032】 On the other hand, drying efficiency can be important for a drying apparatus. That is, it is desirable to reduce the amount of heat wasted. Air temperature causes fluctuations in relative humidity, but it is not related to absolute humidity. Therefore, in this embodiment, it is preferable to provide a heat exchanger that performs heat exchange between the air flowing in from the second supply duct and the air discharged from the first exhaust duct. The heat in the discharged air can be transferred to the incoming air, thereby reducing the waste of heat. 【0033】 The electrode drying apparatus and method according to this embodiment are particularly suitable for drying a negative electrode coated with a negative electrode slurry. The coating liquid is a negative electrode slurry containing a negative electrode active material, a conductive material, a binder, and a solvent, and preferably has a solid content of 50% to 70%. In such an environment, crack formation and side ring formation can be significantly reduced. 【0034】 To achieve the aforementioned objectives, according to one embodiment of the present invention, an electrode drying apparatus may be provided which includes: an air supply fan provided to supply air through an air supply duct to a drying space where an electrode coated with a coating liquid on a current collector is dried; an exhaust fan provided to exhaust air from the drying space through an exhaust duct; a recovery duct that supplies the air discharged from the exhaust fan to the air supply fan; a recovery damper that adjusts the amount of air flowing into the recovery duct; an exhaust damper that adjusts the amount of air exhausted to an external exhaust port through the exhaust duct; an air supply damper that adjusts the amount of air flowing in from an external air supply port through the air supply duct; a main hygrometer that senses the absolute humidity of the air supplied to the drying space; a recovery hygrometer that senses the absolute humidity of the air flowing into the recovery duct; an air supply hygrometer that senses the absolute humidity of the air flowing in from the recovery duct and the external air supply port; and a control unit that adjusts the opening of the recovery damper based on the absolute humidity sensed by the main hygrometer in order to adjust the absolute humidity of the air flowing into the drying space. 【0035】 The control unit can control the amount of recovered air in a multi-stage process during the drying process. In particular, this control can effectively control the absolute humidity of the air supplied to the drying space. 【0036】 The control unit can sequentially perform the following: first-stage damper control or first-stage humidity control, which adjusts the opening of the supply air damper, exhaust damper, and recovery damper based on the absolute humidity sensed by the supply air hygrometer; second-stage damper control or second-stage humidity control, which adjusts the opening of the supply air damper, exhaust damper, and recovery damper based on the absolute humidity sensed by the recovery hygrometer; and third-stage damper control or third-stage humidity control, which adjusts the opening of the supply air damper, exhaust damper, and recovery damper based on the absolute humidity sensed by the main hygrometer. 【0037】 On the other hand, the electrode drying process is carried out continuously. That is, the electrode rolls fed into the roll-to-roll system are moved continuously. In other words, the electrodes are continuously fed into the drying space, dried while moving within the drying space, and then continuously discharged from the drying space. 【0038】 Therefore, the initial stage of the drying process can be described as a preparatory process for drying through the drying apparatus. In other words, it can be described as the stage of setting up a drying environment that ultimately matches the predetermined absolute humidity environment. Thus, the first and second stage controls are processes for adjusting to the absolute humidity environment, and the third stage controls are processes for ultimately performing drying in the absolute humidity environment. 【0039】 After the third stage damper control or humidity control is performed, the electrode drying process is carried out in earnest, and the drying process can be performed continuously. That is, the drying process can be carried out in a roll-to-roll environment, and at this time, the third stage damper control can be continuously and iteratively performed in the form of feedback control based on the absolute humidity sensed by the main hygrometer. 【0040】 The control unit can perform humidification control to control the operation of the humidifier provided in the recovery duct after the third-stage damper control. Considering the recent trend of increasing active material loading at the negative electrode, the required absolute humidity may increase. Therefore, humidification control may be performed repeatedly after the third-stage damper control. The humidification control may be performed intermittently based on the sensing results of the main hygrometer. That is, after humidification control, the third-stage damper control is performed again, and thereafter, if necessary, humidification control may be performed again. 【0041】 According to this embodiment, it is possible to provide a drying apparatus that can very easily provide the required absolute humidity environment by confirming that the absolute humidity factor has an absolute influence on electrode drying. [Effects of the Invention] 【0042】 According to one embodiment of the present invention, it is possible to provide an apparatus and method that can effectively and efficiently dry electrodes while utilizing conventional electrode drying apparatuses and methods without significant modifications. 【0043】 According to one embodiment of the present invention, an apparatus and method can be provided that can reduce the drying deviation in the width direction and effectively prevent the occurrence of cracks and side rings on the electrode surface. 【0044】 According to one embodiment of the present invention, a drying apparatus and method can be provided that can easily and effectively provide the required absolute humidity environment in stages by utilizing multiple hygrometers and dampers. 【0045】 According to one embodiment of the present invention, uniform heating is possible regardless of location within the drying space, thus providing a drying apparatus with a simple structure for the drying oven. [Brief explanation of the drawing] 【0046】 [Figure 1] This is a photograph of the entire coating layer of an electrode that has been dried using a conventional drying device. [Figure 2] These are photographs of both sides of the coating layer of an electrode that has been dried using a conventional drying device. [Figure 3] This is a diagram illustrating an electrode drying apparatus according to one embodiment of the present invention. [Figure 4] This is a control configuration diagram of an electrode drying apparatus according to one embodiment of the present invention. [Figure 5] This is a control flowchart for an electrode drying apparatus according to one embodiment of the present invention. [Figure 6] This is a diagram illustrating the interior of a heat exchanger according to one embodiment of this application. [Modes for carrying out the invention] 【0047】 The electrode drying apparatus of this application will be described below with reference to the attached drawings, which are illustrative examples and the electrode drying apparatus of this application is not limited to those drawings. 【0048】 The inventors were able to confirm that absolute humidity is the absolute factor that has an absolute influence on improving surface cracks and side rings caused by over-drying during electrode drying. In other words, they were able to confirm that when drying is carried out in a drying environment with an appropriate absolute humidity level during the drying process, surface cracks and side rings are absolutely reduced. 【0049】 However, conventional electrode drying devices exhaust the air discharged from the drying oven, making it difficult to provide the appropriate absolute humidity level during the drying process. Therefore, it is conceivable to humidify the air supplied to the drying oven before feeding it into the oven. In other words, an attempt was made to provide the appropriate absolute humidity level by installing a humidifier at the outdoor air supply point. 【0050】 Electrode drying systems that use humidifiers are difficult to control, and the humidifier capacity needs to be large to provide the required amount of moisture, making it difficult to add a humidifier to existing drying systems. In other words, while good drying effects can be expected experimentally by using a humidifier, there are practical difficulties in adding a humidifier in the field. 【0051】 Therefore, the inventors focused on the fact that humidification through exhaust air is possible as a primary means of providing the appropriate absolute humidity, rather than humidification by a humidifier. This is because the air used in the drying process is humidified air obtained by evaporating the solvent from the active material. In other words, they confirmed that the required absolute humidity can be provided by actively using the humidified air as supply air instead of simply exhausting it. 【0052】 Figure 3 is a diagram illustrating an electrode drying apparatus according to one embodiment of this application. 【0053】 As shown in Figure 3, the electrode drying apparatus of this application is a device for drying a coating layer formed by applying a coating liquid to a current collector, and may include an air supply fan 10, a first air supply duct 20, and a second air supply duct 50. When the air supply fan 10 is operated, outside air flows into the first air supply duct 20, and the outside air that has passed the air supply fan 10 can be supplied to the drying section 60. 【0054】 Here, the drying section 60 may be a drying oven having a drying space, and the drying section may be located indoors. That is, the supply air fan 10 and the first supply air duct 20 may be located outdoors, particularly on the roof, and part of the second supply air duct 50 may be located outdoors, with the remaining part extending indoors and connected to the drying section 60. 【0055】 In this embodiment, the first supply air duct 20 may be equipped with a supply air hygrometer 40. The humidity of the supply air can be sensed and the supply air volume can be controlled. In other words, the amount of outside air supplied can be controlled. For controlling the amount of outside air supplied, the first supply air duct 20 may be equipped with a supply air damper 30. 【0056】 When the outside air with appropriate humidity is detected by the supply air hygrometer 40, the supply air volume can be increased, and when the humidity is low, the supply air volume can be decreased. In other words, the supply air volume can be varied by adjusting the opening of the supply air damper 30. 【0057】 The aforementioned outside air refers to air in atmospheric condition and may have a certain absolute humidity depending on the weather. Specifically, the outside air has an absolute humidity of 3 g / m³ as measured through the supply air hygrometer. 3 ~50g / m 3 4g / m 3 ~40g / m 3 , or 5g / m 3 ~30g / m 3 It is possible. 【0058】 In a typical drying process, the air supplied to the drying section 60 absorbs moisture and is then exhausted. However, in this embodiment, the air supplied to the drying section 60 is intended to maintain an appropriate absolute humidity level. Therefore, according to this embodiment, it is preferable to provide a main hygrometer 130 for sensing the absolute humidity level of the air supplied to the drying section 60. 【0059】 The main hygrometer 130 may be installed in the second air supply duct 50. In particular, the main hygrometer 130 may be installed in the section where the drying section 60 and the second air supply duct 50 are connected. That is, it is preferable that the main hygrometer 130 be installed so as to sense the absolute humidity immediately before the air is supplied to the drying section 60. Therefore, it is preferable that the main hygrometer 130 be installed indoors. 【0060】 This embodiment may include an exhaust fan 70. More specifically, the exhaust fan 70 may be provided to exhaust the air used in the drying process from the drying section 60. A first exhaust duct 80 may be provided between the exhaust fan 70 and the drying section 60. Part of the first exhaust duct 80 may be provided indoors and the remaining part outdoors and connected to the exhaust fan 70. Of course, the exhaust fan 70 may also be provided outdoors. 【0061】 The exhaust fan 70 is connected to the second exhaust duct 110 and exhausts the air used in the drying process to the outside through the external exhaust port. 【0062】 Generally, the air drawn into the exhaust fan 70 is completely exhausted to the outside through the second exhaust duct 110. This is because the air used in the drying process contains a lot of moisture, and it is common knowledge that supplying this air back to the drying section 60 would reduce drying efficiency. In other words, it is common knowledge that supplying high-temperature dry air to the drying section 60 and then exhausting the high-temperature, high-humidity air after drying increases drying efficiency. 【0063】 However, in this embodiment, the crack and side ring problems can be fundamentally solved by performing the drying process while maintaining an appropriate absolute humidity level. Therefore, in this embodiment, the exhaust fan 70 can be said to be a means for recovering moisture from hot and humid air rather than a means for completely exhausting air. In other words, it can be said to be a means for recovering and resupplying moisture. Therefore, in this embodiment, the exhaust fan 70 can be called a recovery exhaust fan 70. 【0064】 The second exhaust duct 110 may be equipped with an exhaust damper 120. The amount of exhaust can be controlled by adjusting the opening and closing amount of the exhaust damper 120. Preferably, the control of the exhaust damper 120 is linked to the control of the recovery damper 100, which will be described later. 【0065】 A recovery duct 150 may be provided, branched from the second exhaust duct 110. The recovery duct 150 may be connected to the first supply air duct 20. That is, a portion of the exhausted air flows into the recovery duct 150 and can then be resupplied to the drying section 60 through the first supply air duct 20. At this time, it can be said that moisture is recovered from the exhausted air and reused. 【0066】 The recovery duct 150 may be equipped with a recovery damper 100. The amount of air recovered can be adjusted by adjusting the opening of the recovery damper 100. 【0067】 The amount of air supplied and the amount of air exhausted must be balanced based on the drying section 60. From another perspective, the differential pressure across the supply fan 10 and the differential pressure across the recovery exhaust fan 70 must be properly maintained. 【0068】 Therefore, from the viewpoint of air supply, it is preferable that the opening rates of the air supply damper 30 and the recovery damper 100 are controlled in conjunction with each other. Also, from the viewpoint of exhaust, it is preferable that the opening rates of the exhaust damper 120 and the recovery damper 100 are controlled in conjunction with each other. 【0069】 In this embodiment, the recovery damper 100 can be actively controlled. The air flowing into the second exhaust duct 110 is very humid. Therefore, moisture can be recovered, and this can be done by actively recovering moisture from the air exhausted through the recovery duct 150 and resupplying it. 【0070】 For this purpose, the recovery duct 150 may be equipped with a recovery hygrometer 90. The absolute humidity of the air recovered can be sensed through the recovery hygrometer 90. Then, moisture can be actively recovered by increasing the opening of the recovery damper 100. During the initial drying process, the possibility of over-drying is low, so it is preferable that the exhaust volume is greater than the recovered volume. However, during the main drying process, the possibility of over-drying is high, so it is preferable that the recovered volume is greater than the exhaust volume. In other words, it is preferable to actively recover moisture and perform drying while maintaining an appropriate absolute humidity level. 【0071】 In other words, during the initial setup phase of the drying apparatus, the amount of recovered air is controlled to be relatively small to heat the inside of the drying space, and during the main drying process through the drying apparatus, the amount of recovered air is controlled to be relatively large to match the required absolute humidity. 【0072】 It is preferable that the opening of the exhaust damper 120 decreases relatively as the opening of the recovery damper 100 increases. Conversely, it is preferable that the opening of the exhaust damper 120 increases as the opening of the recovery damper 100 decreases. 【0073】 On the other hand, it is preferable that the opening of the supply air damper 30 decreases relatively as the opening of the recovery damper 100 increases. Conversely, it is preferable that the opening of the supply air damper 30 increases as the opening of the recovery damper decreases. 【0074】 Here, both outside air and recovered air are supplied to the drying section 60, but the ratio of outside air to recovered air changes depending on the opening of the recovery damper 100 and the supply air damper 30. In other words, the mixed air is supplied directly to the drying section 60, and the absolute humidity of this mixed air is very important. If the absolute humidity of the recovered air is higher than that of the outside air, and if it is necessary to increase the required amount of absolute humidity, the ratio of recovered air can be controlled to be higher than that of outside air. That is, it is preferable to control the system so that the opening of the recovery damper increases and the opening of the supply air damper decreases. Similarly, it is preferable to control the system so that if the opening of the recovery damper increases, the opening of the exhaust damper decreases. 【0075】 Since the outside air has the absolute humidity described above, the opening amounts of the supply air damper and the recovery damper can be controlled differently based on the absolute humidity measured by the supply air hygrometer described later. Through this, the electrode drying apparatus can reduce the consumption and installation costs incurred during electrode drying, reduce the drying deviation in the width direction, and lower the crack occurrence rate on the electrode surface. In this specification, the term "set value" means the absolute humidity value set so that the moisture inside the drying section has excellent absolute humidity. 【0076】 The air supply damper 30 is a device that adjusts the amount of outside air supplied along the first air supply duct and is installed inside the first air supply duct. By adjusting the amount of outside air supplied at the aforementioned position, the air supply damper can control the drying rate of the coating liquid coated on the current collector, thereby controlling the adhesive force between the current collector and the coating layer. Furthermore, by adjusting the amount of outside air supplied at the aforementioned position, the air supply damper can control the differential pressure between the outside air flowing into the drying section, i.e., the supply air, and the moisture discharged from the drying section, i.e., the exhaust air, thereby controlling the absolute amount of drying of the coating liquid coated on the current collector. 【0077】 In one example, since the outside air may have a certain absolute humidity depending on the season, the opening angle of the air supply damper is not particularly limited and may be, for example, greater than 0% and less than or equal to 100%. The air supply damper can have a constant absolute humidity across the entire range of the aforementioned opening angles. Therefore, the opening angle of the air supply damper may be set differently depending on the season during the initial operation of the drying device. 【0078】 The air supply hygrometer 40 is a sensor that measures the absolute humidity of the outside air supplied to the first air supply duct 20, and is installed inside the first air supply duct. By installing the air supply hygrometer in the aforementioned position, it becomes possible to measure the absolute humidity of the outside air supplied to the first air supply duct. During the initial operation of the drying apparatus, the absolute humidity of the air flowing in from the recovery duct may be low. Therefore, initially, the opening ratio of the air supply damper 30 can be set and controlled to be higher than the opening ratio of the recovery damper based on the sensing result of the air supply hygrometer 40. 【0079】 An electrode current collector is an element configured to have low electrical resistance and to transmit current to or from the active material during charging and discharging. As the current collector, any negative electrode current collector that is conductive without inducing chemical changes in the battery in the art can be used and is not particularly limited. For example, the negative electrode current collector can be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel whose surfaces have been treated with carbon, nickel, titanium, silver, etc. 【0080】 The coating layer is formed by applying a coating liquid to the current collector, specifically to one or both sides of the current collector. The coating liquid is not particularly limited and can be any negative electrode slurry used to form a negative electrode in the art. For example, the negative electrode slurry may contain a negative electrode active material, a conductive material, a binder, and a solvent. 【0081】 The anode active material can be any anode active material used in the art, and is not particularly limited. For example, the anode active material may be at least one of a carbon-based active material and a silicon-based active material. 【0082】 The carbon-based active material can be one or more selected from the group consisting of artificial graphite, natural graphite, graphitized carbon fiber, and graphitized mesocarbon microbeads. The silicon-based active material is SiO X (0≦X<2), one or more elements selected from the group consisting of Si-C composites and Si-Y alloys (where Y is an element selected from the group consisting of alkali metals, alkaline earth metals, transition metals, group 13 elements, group 14 elements, rare earth elements, and combinations thereof) can be used. 【0083】 The conductive material can be any conductive material that has conductivity in the art without inducing a chemical change in the battery, and is not particularly limited. For example, the conductive material may be graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; conductive fibers such as carbon fibers or metal fibers; conductive tubes such as carbon nanotubes; fluorocarbons; metal powders such as aluminum or nickel; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive materials such as polyphenylene derivatives. 【0084】 The binder is for ensuring adhesion between the negative electrode active materials or between the negative electrode active materials and the current collector, and all binders used in the art may be used and are not particularly limited. For example, the binder may be polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one or more of these may be used. 【0085】 Examples of the aforementioned solvents include amide-based polar organic solvents such as water, dimethylformamide (DMF), diethylformamide, dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP); alcohols such as methanol, ethanol, 1-propanol, 2-propanol (isopropyl alcohol), 1-butanol (n-butanol), 2-methyl-1-propanol (isobutanol), 2-butanol (sec-butanol), 1-methyl-2-propanol (tert-butanol), pentanol, hexanol, heptanol, and octanol; glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, and hexylene glycol; and glycerin, trimethylolpropane, pentaerythritol, or sorbitanol. Examples include polyhydric alcohols such as thol; glycol ethers such as ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, and tetraethylene glycol monobutyl ether; ketones such as acetone, methyl ethyl ketone, methyl propyl ketone, and cyclopentanone; or esters such as ethyl acetate, γ-butyl lactone, and ε-propiolactone. Any one or a mixture of two or more of these may be used. 【0086】 In one example, the coating liquid may have a solid content of 50% to 70%. Specifically, the solid content of the coating liquid may be 53% to 68%, 55% to 65%, or 58% to 63%. By having the aforementioned solid content, the coating liquid exhibits high loading, with less water evaporating during drying and the remaining solid content coating the current collector, resulting in superior capacity and charging time. 【0087】 Furthermore, the coating layer can be controlled so that a slope-shaped sliding section is generated on the side surface by the flow of the liquid, resulting in a relatively larger loading amount in the center compared to the side surface. This allows the thickness of the coating layer to be controlled to be uniform across the entire surface. 【0088】 In one example, the electrode drying apparatus may further include a heat exchanger 140. The heat exchanger is a device for increasing the temperature of the air moving through the second supply air duct 50 through heat exchange between the air moving through the second supply air duct 50 and the air moving through the first exhaust duct 80. For example, a commercially available plate-type heat exchanger can be used as the heat exchanger. 【0089】 Figure 6 is a diagram illustrating the interior of a heat exchanger provided in a drying apparatus according to one embodiment of the present invention. 【0090】 As shown in Figure 6, the heat exchanger 140 may include a plurality of heat plates 141 arranged spaced apart from each other, a first lower pipe 142 communicating with the lower end of the first side surface of the plurality of heat plates, a first upper pipe 143 communicating with the upper end of the first side surface of the plurality of heat plates, a second upper pipe 145 communicating with the upper end of the second side surface of the plurality of heat plates, and a second lower pipe 144 communicating with the lower end of the second side surface of the plurality of heat plates. 【0091】 Specifically, the air moving through the second air supply duct 50 flows into and moves through the first lower pipe, and the air moving through the first exhaust duct flows into and moves through the second upper pipe. At this time, air moves between each of the multiple heat plates, resulting in heat exchange. 【0092】 The air that has been heated moves to the first upper pipe, and the air that has moved to the first upper pipe can be discharged from the first upper pipe and flow back into the second supply air duct 50. In addition, the heated air moves to the second lower pipe, and the air that has moved to the second lower pipe can be discharged from the second lower pipe and flow back into the exhaust duct. 【0093】 Through this, hot air that has passed through the heat exchanger can be introduced into the drying section, thereby drying the coating layer formed by applying the coating liquid to the current collector. 【0094】 In one further example, the drying section 60 may further include a heat transfer oil pipe. The heat transfer oil is a high-temperature oil that can move along the heat transfer oil pipe. For example, the heat transfer oil pipe may be a commercially available heat transfer oil pipe, which can heat the outside air to form hot air by a method known in the industry. By further including the aforementioned heat transfer oil pipe inside the drying section, the outside air moving through the second air supply duct can be heated to form hot air which is then introduced into the drying section, thereby drying the coating layer formed by applying the coating liquid to the current collector. 【0095】 At this time, the set temperature of the electrode drying device for forming hot air by the heat exchanger and / or heat transfer oil piping may be 50°C to 165°C, specifically 65°C to 150°C, 80°C to 135°C, or 95°C to 120°C. By the set temperature of the electrode drying device described above satisfying the aforementioned range, the absolute humidity of the moisture evaporated during the drying of the coating layer formed by applying the coating liquid to the current collector can be improved. 【0096】 In one further example, the drying unit may further include a mid-infrared (MIR) drying device. Specifically, if the incoming hot air does not reach the aforementioned set temperature, the drying unit can directly heat the hot air through the mid-infrared drying device to raise its temperature to the aforementioned set temperature. 【0097】 The control configuration and control method according to one embodiment of the present invention will be described in detail below with reference to Figures 4 and 5. 【0098】 The control unit 200 is a controller provided to control the operation of the drying apparatus, and may be configured in particular to control the drying environment. 【0099】 The drying section 60 is a space for heating the electrodes, and the amount of heat to be heated can be continuously controlled through the control unit 200. 【0100】 The control unit 200 can control the operation of various fans 10 and 70 and various dampers 30, 100, and 120. Control of such a configuration can be performed based on the absolute humidity sensed by various hygrometers 130, 40, and 90. 【0101】 Specifically, the control unit 200 can control the opening degrees of the supply air damper 30, the recovery damper 100, and the exhaust damper 120 based on the absolute humidity sensed by the main hygrometer 130, the supply air hygrometer 40, and the recovery hygrometer 90. 【0102】 The control unit 200 can control the operation of various dampers in order to supply the ultimate optimal absolute humidity environment to the dry space. In other words, it can control the absolute humidity of the air supplied to the dry space to be optimal. Therefore, the most important control factor is the absolute humidity sensed by the main hygrometer 130. 【0103】 However, it is preferable to create an absolute humidity environment gradually, either during the initial operation of the drying device or due to seasonal variations. 【0104】 In other words, when the drying device starts operating (S10), the first stage control (S20) is performed, in which case the control factor is the absolute humidity sensed by the supply air hygrometer 40. Based on the required absolute humidity, the control unit 200 temporarily adjusts the opening degrees of the various dampers 30, 100, and 120. The first stage control can be said to be a stage that reflects the absolute humidity of the outside air. 【0105】 After the completion of the first stage control (S20), the second stage control (S30) may be performed. In this case, the control factor is the absolute humidity sensed by the recovered hygrometer 90. The control unit 200 will secondarily adjust the opening degrees of the various dampers 30, 100, and 120 according to the required absolute humidity. The second stage control can be described as a stage to reflect the absolute humidity of the recovered air. 【0106】 After the completion of the second stage control (S30), the third stage control (S40) may be performed. In this case, the control factor is the absolute humidity sensed by the main hygrometer 130. Based on the required absolute humidity, the control unit 200 will ultimately adjust the opening of the various dampers 30, 100, and 120. In other words, the final control of the dampers is ultimately to sense the required absolute humidity from the main hygrometer 130 and ensure that the dry environment becomes an optimal absolute humidity environment. 【0107】 The third stage control (S40) can be performed continuously to allow the electrodes to be dried effectively and stably in a continuous manner (S60). 【0108】 On the other hand, if the loading amount is large, it may be difficult to provide a sufficient absolute humidity environment through the third-stage control (S40). In this case, humidification control (S50) may be performed. If it is difficult to create the required absolute humidity environment even by making maximum use of the recovered moisture, additional moisture can be supplied. 【0109】 Humidification control (S50) may be performed intermittently, and humidification control (S50) and third-stage control (S40) may be repeated in accordance with the absolute humidity sensed by the main hygrometer 130. The drying process may be continued (S60) through these stages. 【0110】 Humidifier 160 can perform not only humidification but also filtering functions. Since the collected air may contain foreign matter, filtered air can be resupplied through the filtering function.

Claims

[Claim 1] An air supply fan is provided to supply air through an air supply duct to a drying space where electrodes coated with a coating liquid are dried on the current collector, An exhaust fan is provided to exhaust air from the aforementioned drying space through an exhaust duct, A recovery duct that supplies the air discharged from the exhaust fan to the intake fan, A recovery damper that adjusts the amount of air flowing into the recovery duct, A main hygrometer that senses the absolute humidity of the air supplied to the dry space, The system includes a control unit that adjusts the opening of the recovery damper based on the absolute humidity sensed by the main hygrometer in order to adjust the absolute humidity with the air flowing into the dry space, The exhaust duct includes a first exhaust duct connecting the drying space and the exhaust fan, and a second exhaust duct connecting the exhaust fan and the external exhaust port. The air supply duct includes a first air supply duct connecting the external air supply port and the air supply fan, and a second air supply duct connecting the air supply fan and the drying space. The recovery duct is branched from the second exhaust duct and connected to the first supply duct. The second exhaust duct is equipped with an exhaust damper that adjusts the amount of air exhausted to the external exhaust port. The exhaust damper is provided at the rear end of the branching point of the recovery duct. The recovery duct is equipped with a recovery hygrometer that senses the absolute humidity of the air flowing into the first supply duct through the recovery duct. The control unit adjusts the opening degree of the recovery damper based on the absolute humidity sensed by the recovery hygrometer. The control unit adjusts the opening of the exhaust damper to decrease as the opening of the recovery damper increases. An electrode drying apparatus, wherein the first air supply duct is equipped with an air supply damper that adjusts the amount of air flowing in from the external air supply port. [Claim 2] The electrode drying apparatus according to claim 1, wherein the air supply damper is provided at the front end of the confluence point of the recovery duct. [Claim 3] The electrode drying apparatus according to claim 2, wherein the first supply air duct is equipped with a supply air hygrometer that senses the absolute humidity of the air flowing in from the recovery duct and the external supply air port. [Claim 4] The electrode drying apparatus according to claim 3, wherein the control unit adjusts the opening degree of the recovery damper and the supply air damper based on the absolute humidity sensed by the supply air humidity meter. [Claim 5] The electrode drying apparatus according to claim 4, wherein the recovery duct is equipped with a humidifier. [Claim 6] The electrode drying apparatus according to claim 5, wherein the control unit controls the humidifier to perform humidification when the absolute humidity sensed by the main hygrometer is lower than a previously set value. [Claim 7] The electrode drying apparatus according to claim 1, further comprising a heat exchanger that performs heat exchange between air flowing in from the second supply air duct and air discharged from the first exhaust duct. [Claim 8] The electrode drying apparatus according to claim 1, wherein the coating liquid is a negative electrode slurry containing a negative electrode active material, a conductive material, a binder, and a solvent, and has a solid content of 50% to 70%. [Claim 9] An air supply fan is provided to supply air through an air supply duct to a drying space where electrodes coated with a coating liquid are dried on the current collector, An exhaust fan is provided to exhaust air from the aforementioned drying space through an exhaust duct, A recovery duct that supplies the air discharged from the exhaust fan to the intake fan, A recovery damper that adjusts the amount of air flowing into the recovery duct, An exhaust damper that adjusts the amount of air exhausted to an external exhaust port through the aforementioned exhaust duct, A supply air damper that adjusts the amount of air flowing in from the external air inlet through the aforementioned supply air duct, A main hygrometer that senses the absolute humidity of the air supplied to the dry space, A recovery hygrometer that senses the absolute humidity of the air flowing into the recovery duct, A supply air hygrometer that senses the absolute humidity of the air flowing in from the recovery duct and the external air inlet, The system includes a control unit that adjusts the opening of the recovery damper based on the absolute humidity sensed by the main hygrometer in order to adjust the absolute humidity with the air flowing into the dry space, The control unit adjusts the opening degree of the recovery damper based on the absolute humidity sensed by the recovery hygrometer. The control unit adjusts the opening of the exhaust damper to decrease as the opening of the recovery damper increases, in an electrode drying apparatus. [Claim 10] The control unit, A first-stage damper control system adjusts the opening degrees of the supply air damper, the exhaust damper, and the recovery damper based on the absolute humidity sensed by the supply air hygrometer. A second-stage damper control system adjusts the opening degrees of the supply air damper, the exhaust damper, and the recovery damper based on the absolute humidity sensed by the recovery hygrometer. The electrode drying apparatus according to claim 9, further comprising sequentially performing a third-stage damper control, which adjusts the opening degrees of the supply air damper, the exhaust damper, and the recovery damper based on the absolute humidity sensed by the main hygrometer. [Claim 11] The electrode drying apparatus according to claim 10, wherein the control unit performs humidification control to control the operation of a humidifier provided in the recovery duct after the third-stage damper control.

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