JP2007227831A - Method and apparatus of manufacturing electrode for electrochemical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid the occurrence of microcracks on the surfaces of electrodes in the case of applying electrode material on a collector used of an electrochemical element etc. and drying it, and to improve productivity in the case. <P>SOLUTION: A method of manufacturing the electrodes of the electrochemical element has an application process of applying the electrode material on the collector 2 made of a metallic foil, and a drying process of drying the collector 2 to which the electrode material is applied in a drying chamber. The drying process has a first drying process of drying the collector 2 until reaching a critical moisture content of the electrode material, when a diffusion speed in the electrode material on nearly the whole surface of the electrode material becomes lower than the evaporation speed of water from a free water surface; and a second drying process of drying thereafter. A heat transmission speed is higher in the first drying process than in the second drying process. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing an electrochemical element electrode body used for producing an electrochemical element having excellent productivity and reliability, and an electrochemical element electrode body production apparatus using the same. is there.

  A conventional electrochemical element is obtained by applying an electrode material on the surface of a current collector such as a metal foil and then drying it to produce an electrode body. The electrode bodies are paired with a separator therebetween. It constitutes an electrochemical element.

  Depending on the dry state of the electrode material, the adhesion between the current collector and the electrode material, the binding force between the electrode materials, and the like are determined, which greatly influences the characteristics of the electrochemical element.

  Conventionally, in a drying process, after applying a liquid electrode material on a current collector, drying was performed with an emphasis on drying quickly. Therefore, an amount of heat was applied to the electrode material more than necessary. As a result, fine cracks or the like were generated, and the function as an electrode was impaired.

  Moreover, in the electrode dried by the conventional drying process, when the electrode is wound, the electrode is curved, so that the electrode material may be peeled off from the current collector or a fine crack may be generated. . These also impair the function as an electrode.

  Therefore, in the conventional drying process, to a certain extent, gradually increase the heat transfer rate, which is one index representing the strength of drying, and then further increase the temperature or increase the amount of hot air, Drying methods such as further increasing the heat transfer rate, or gradually decreasing the heat transfer rate to a certain extent, then lowering the temperature or reducing the amount of hot air to further decrease the heat transfer rate The method was used.

For example, Patent Document 1 and Patent Document 2 are known as prior art document information related to the invention of this application.
JP 2003-205264 A JP 2004-28495 A

  In the above conventional manufacturing method, the heat transfer rate applied to the electrode material is gradually increased from a low heat transfer rate to a high heat transfer rate, or is gradually decreased from a high heat transfer rate to a low heat transfer rate. The electrode material was dried by going. When the electrode material is dried by these methods, fine cracks are generated on the surface, and the function as an electrode is impaired as described above, resulting in an unreliable electrochemical element, or productivity. Would be reduced.

  Therefore, the present invention provides an electrode body for an electrochemical element that does not generate fine cracks on the surface of the electrode and can improve productivity when the electrode material applied on the current collector is dried. It aims at providing the manufacturing method and the manufacturing apparatus of the electrode body for electrochemical devices using the same.

  In order to achieve this object, the present invention is designed such that when the electrode material is applied on the current collector and then dried in a drying chamber, the diffusion rate in the electrode material on almost the entire surface of the electrode material is reduced from the free water surface. The heat transfer rate given to the electrode material in the first drying step, which is a drying step until the moisture content of the electrode material reaches the limit moisture content at the time when the water evaporation rate becomes smaller than the water evaporation rate, is The production method is higher than the heat transfer rate applied to the electrode material in the second drying step, which is a drying step after the electrode material reaches the limit moisture content.

  The method for producing an electrode body for an electrochemical device according to the present invention can produce an electrochemical device excellent in reliability without reducing productivity by changing the drying conditions with the critical moisture content as a boundary. It is.

(Embodiment 1)
Hereinafter, a drying method after applying an electrode material to a coating apparatus and a continuously running current collector in Embodiment 1 of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram of a coating apparatus according to Embodiment 1 of the present invention.

  First, the coating apparatus 1 shown in FIG. 1 will be described. The coating device 1 has an unwinding roll 5, a roll 8, a backup roll 7, a roll 9, a roll 10, and a winding roll 6 in order to continuously run the current collector 2.

  In FIG. 1, only the minimum number of rolls necessary for continuously running the current collector 2 are described, but the number and types of rolls are not particularly limited.

  In addition, the coating apparatus 1 has a coating machine 3 and a backup roll 7 for coating an electrode material (hereinafter not shown) on the current collector 2, and the backup roll 7 depends on the coating machine 3 used. It may not be necessary.

  As the coating machine 3, a doctor blade coater, a die coater, a gravure coater, a micro gravure coater, a roll coater, or the like can be used, but the apparatus is not particularly limited, and an apparatus that can apply an electrode material on the current collector 2. Any other device may be used as long as it is.

  Further, the coating device 1 includes a drying device 4 for drying the electrode material applied on the current collector 2.

  Desirably, the drying apparatus 4 has two or more drying chambers 11 capable of independently controlling the drying conditions, and has three or more drying chambers 11 capable of independently controlling the drying conditions. If so, it is more desirable.

  In the drying chamber 11, at least one of a dryer using a mechanism based on conduction heat transfer, a dryer using a mechanism based on convection heat transfer, and a dryer using a mechanism based on heat dissipation heat transfer as a dryer. Has a dryer.

  As a dryer using a mechanism based on conduction heat transfer, a dryer such as a cylindrical dryer or a drum dryer can be used. However, the type of the dryer is not particularly limited, and a mechanism based on conduction heat transfer is used. Any other dryer may be used as long as it is a dryer.

  As a dryer using a mechanism by convection heat transfer, a hot air dryer or the like can be used, but the type of the dryer is not particularly limited, and if it is a dryer using a mechanism by convection heat transfer, Any other dryer may be used.

  The hot air dryer has a co-current operation in which hot air flows in the same direction as the current collector 2, a counter current operation in which hot air flows in a direction opposite to the current collector 2, and current collector 2. Although operations such as flowing hot air at right angles to the current collector 2 can be performed from the surface side where the electrode material is applied on the surface and / or the surface side where the electrode material is not applied, the direction of flowing the hot air is particularly limited However, in order to dry the electrode material applied on the current collector 2, an operation of flowing hot air from all directions of one or more directions may be performed.

  As a dryer using a mechanism by radiant heat transfer, a near-infrared dryer, a mid-infrared dryer, a far-infrared dryer, an infrared dryer, etc. can be used, but the type of dryer is not particularly limited. Any other dryer may be used as long as the dryer uses a mechanism based on radiant heat transfer.

  Further, the inside of the drying chamber 11 is preferably filled with a gas such as dry air, nitrogen gas, or argon gas having a relative humidity of 30% or less. However, the type of gas in the drying chamber 11 is not particularly limited. As long as the relative humidity is 30% or less, any other gas can be used as a desirable condition.

  At this time, if a gas having a relative humidity of 30% or less is used, the saturated humidity of the gas (kg / kg · dry air), which becomes a driving force when the electrode material applied on the current collector 2 by the coating machine 3 is dried. ) And the humidity of the gas in the drying chamber 11 (kg / kg · dry air) is increased, so that the drying speed can be increased.

  Further, the inside of the drying chamber 11 is not necessarily filled with gas, and the gas in the drying chamber 11 may be evacuated using a vacuum pump or the like. By performing evacuation, the component evaporated from the electrode material can be removed from the inside of the drying chamber 11, so that the drying speed can be increased.

  The width of the dryer disposed in the drying chamber 11 is preferably wider than the width of the current collector 2. Thus, by making the width of the dryer disposed in the drying chamber 11 wider than the width of the current collector 2, a large amount of heat can be collected even under drying conditions where the heat transfer rate per unit area is low. It can give to the electrode material apply | coated by the coating device 3 on the electric body 2, and can dry an electrode material in a short time.

  Although the length of the drying chamber 11 is not particularly defined, it is more desirable to define the drying chamber 11 with a length described later, and it is more desirable to obtain an electrode that is soft, free from cracks and peeling, and has a smooth surface. it can.

  In the case of having three drying chambers 11 that can control drying conditions independently as shown in FIG. 1, the drying chamber into which the current collector 2 supplied from the unwinding roll 5 enters first. 11 is the first drying chamber 11a, the next drying chamber 11 is the second drying chamber 11b, and finally the drying chamber 11 through which the current collector 2 passes is the third drying chamber 11c. In contrast, the length of the first drying chamber 11a is 1/10 or more, the length of the second drying chamber 11b is 4/5 or less, and the length of the third drying chamber 11c is 1/10 or more. What should I do.

  Even in the drying apparatus 4 having four or more drying chambers 11 capable of independently controlling the drying conditions, by considering a plurality of continuous drying chambers 11 as zones, the three drying zones are provided. The length of the first drying zone is 1/10 or more, the length of the second drying zone is 4/5 or less, and the length of the third drying zone is 1/0 of the length of the drying device 4. What is necessary is just to make it 10 or more.

  Here, how to separate the drying zones in the drying apparatus 4 having four or more drying chambers 11 capable of independently controlling the drying conditions will be described.

  First, the first drying zone is a drying chamber continuous from the first drying chamber 11a, and dries the electrode material applied on the current collector 2 at a heat transfer rate higher than that of the previous drying chamber 11. This is an assembly of drying chambers 11 having the ability.

  The second drying zone is a drying chamber 11 continuous from the final drying chamber 11 of the first zone, and is applied onto the current collector 2 at a heat transfer rate equal to or lower than the final drying chamber 11 of the first zone. Ability to dry the electrode material applied on the current collector 2 at a heat transfer rate lower than that of the previous drying chamber 11, which is continuous with the drying chamber 11 having the ability to dry the applied electrode material It is an assembly of the drying chamber 11 having

  Further, the third drying zone is a drying chamber 11 that is continuous from the final drying chamber 11 of the second zone, and is on the current collector 2 at a heat transfer rate higher than that of the final drying chamber 11 of the second drying zone. It is an aggregate of all the drying chambers 11 after the drying chamber 11 having the ability to dry the electrode material applied to the.

  In addition, about the drying chamber 11 of a 1st zone, the drying chamber 11 which has the capability to dry the electrode material apply | coated on the electrical power collector 2 at the heat transfer rate of the drying chamber 11 immediately before 1 is intermittently used. Even if the electrode material is included, the electrode material is applied onto the current collector 2 by the applicator 3, and is dried using the drying device 4 having the first drying zone, the second drying zone, and the third drying zone. By doing so, it is possible to obtain an electrode that is soft, free from cracks and peeling, and has a smooth surface.

  The drying chamber 11 in the second zone includes the drying chamber 11 having the ability to dry the electrode material applied on the current collector 2 at a rate higher than the heat transfer rate of the previous drying chamber 11 intermittently. However, the electrode material is applied onto the current collector 2 by the applicator 3 and dried using the drying device 4 having the first drying zone, the second drying zone, and the third drying zone. Thus, an electrode that is soft, has no cracks or peeling, and has a smooth surface can be obtained.

  Further, in the first drying chamber 11a or the drying chamber 11 in the first zone, the moisture content of the electrode material applied on the current collector 2 by the coating machine 3 = (solvent weight in the electrode material / inside of the electrode material) It is desirable to provide a dryer that can be dried to a limit moisture content that is a moisture content at the boundary between the constant rate drying period and the reduced rate drying period.

  In the first drying chamber 11a or in the drying chamber 11 in the first zone, a dryer capable of drying the electrode material coated on the current collector 2 by the coating machine 3 to the limit moisture content is provided. If so, an electrode material is applied onto the current collector 2 by the applicator 3 and dried by the drying device 4, whereby an electrode that is soft, free from cracks and peeling, and has a smooth surface can be obtained.

  Here, the expression of water content in the present invention will be described. The water content is not limited to the case where the solvent is water, but is expressed as the water content even when the solvent is water, an organic solvent, or any other liquid.

  Further, it is desirable to use a dryer using a mechanism by radiant heat transfer in the first drying chamber 11a or the drying chamber 11 in the first zone. If a dryer using a mechanism based on radiant heat transfer is used in the first drying chamber 11a or the drying chamber 11 in the first zone, a dryer using a mechanism based on conductive heat transfer or a mechanism based on convective heat transfer is used. Since it is possible to apply a large amount of heat to the electrode material coated on the current collector 2 by the coating machine 3 in a relatively simpler manner than the drying machine, initial drying can be performed in a short time.

  In addition, it is desirable to use a dryer using a mechanism by radiant heat transfer in the third drying chamber 11c or in the drying chamber 11 in the third zone. If a dryer using a mechanism based on radiant heat transfer is used in the third drying chamber 11c or the dryer chamber 11 in the third zone, a dryer using a mechanism based on conductive heat transfer or a mechanism based on convective heat transfer is used. Since a larger amount of heat can be applied to the electrode material coated on the current collector 2 by the coating machine 3 than the dryer, the electrode material coated on the current collector 2 by the coating machine 3 can be dried. Residual moisture content in the electrode obtained by drying according to 4 = (weight of the solvent contained in the electrode) / (weight of the electrode) is dried to a desired residual moisture content in a short time. Can do.

  Here, the expression of the residual moisture content in the present invention will be described. The residual moisture content is not limited to the case where the solvent is water, but is expressed as the residual moisture content even when the solvent is water, an organic solvent, or any other liquid.

  Further, it is desirable that the coating apparatus 1 has a mechanism for applying tension to the current collector 2 by using an apparatus such as a powder clutch or a dancer, but the apparatus for applying the tension is particularly limited. Instead, any other device can be used as long as it is a device for applying tension to the current collector 2.

  Furthermore, it is desirable that the coating apparatus 1 has a nip roll or the like in order to change the magnitude of the tension applied to the current collector 2 in an arbitrary range. In particular, the tension applied to the current collector 2 in an arbitrary range. The mechanism for changing the magnitude of the current is not limited, and any other mechanism can be used as long as it is a mechanism for changing the magnitude of the tension applied to the current collector 2 within an arbitrary range. be able to.

  The coating apparatus 1 desirably has a mechanism that can vary the supply speed of the current collector 2. Further, the supply speed of the current collector 2 is set to a time from 5 seconds to 120 seconds from when the current collector 2 enters the first drying chamber 11a to when it comes out of the second drying chamber 11b or the second drying zone. It is more desirable to have a mechanism that can be controlled as follows.

  In addition, there is a mechanism capable of controlling the supply speed of the current collector 2 from 10 seconds to 180 seconds after the current collector 2 enters the first drying chamber 11a until it comes out from the final drying chamber 11x. If so, it is more desirable.

  The supply speed of the current collector 2 is set to 5 seconds or more and 120 seconds or less from when the current collector 2 enters the first drying chamber 11a until it comes out of the second drying chamber 11b or the second drying zone. The controllable mechanism and / or the supply speed of the current collector 2 The time from when the current collector 2 enters the first drying chamber 11a to when it comes out from the final drying chamber 11x is 10 seconds or more and 180 seconds or less If the electrode has a mechanism that can be controlled, the electrode material is applied onto the current collector 2 by the coating machine 3 and dried by the drying device 4 so that the electrode is soft, free of cracks and peeling, and has a smooth surface. Can be obtained in a short time.

  Next, an electrode material is applied on the current collector 2 by the coating machine 3 using the coating device 1 and the electrode material applied on the current collector 2 is dried by the drying device 4 to obtain an electrode. A method will be described. In the first embodiment, a method for manufacturing an electrode for an electrochemical capacitor will be described as a specific example. However, the application of the electrode is not particularly limited, and the electrode can be obtained by the same method as in the first embodiment. The present invention can be used in any other application as long as the electrode can be used.

  As an electrode material, a solution in which a solute such as a polymer material or a polymer resin is dissolved in a solvent such as water or an organic solvent can be used. However, the type of the solvent and the solute is not particularly limited, and any solvent And solutes can be used.

  Moreover, you may use the solvent which mixed the several solvent as a solvent. Furthermore, a solute obtained by mixing a plurality of solutes may be used.

  Moreover, an emulsion can be used as an electrode material. The emulsion is an O / W type emulsion prepared by gradually adding an aqueous phase to an oil phase containing an emulsifier, or a W / O type prepared by gradually adding an oil phase to an aqueous phase containing an emulsifier. Emulsions include O / W / O type emulsions and W / O / W type emulsions that are multilayer emulsions prepared by performing these operations a plurality of times, but the type of emulsion is not particularly limited. Any other emulsion can be used as long as it exists.

  Furthermore, a particle dispersion can be used as the electrode material. As the liquid for dispersing the particles, water, an organic solvent, or the like can be used. However, the type of the liquid is not particularly limited, and any other liquid may be used as long as it is a liquid.

  Further, a liquid in which particles are dispersed may be a liquid in which a plurality of liquids are mixed. Further, as the particles dispersed in the liquid, carbon materials such as activated carbon, graphite, and carbon black, ceramic materials, polymer materials, metals, and the like can be used. Any particles can be used as long as they are present.

  Here, as the electrode material, a solution, an emulsion, a dispersion of particles, and the like can be used. However, the type of the liquid is not particularly limited, and any other liquid can be used.

  In addition, a solution, an emulsion, and a dispersion of particles may be used alone as an electrode material, but a mixture of one or more types of solutions and one or more types of emulsions, one or more types of solutions, and one or more types of particles. A liquid mixture of the above-mentioned dispersion liquid and a liquid mixture of one or more kinds of emulsions and one or more kinds of particle dispersions may be used.

  Furthermore, a mixture of one or more types of solutions, one or more types of emulsions, and a dispersion of one or more types of particles may be used.

  Further, the moisture content of the electrode material before being applied onto the current collector 2 by the applicator 3 varies depending on the electrode material used, and in particular, the electrode material before being applied onto the current collector 2 by the applicator 3. It does not limit the moisture content.

  In Embodiment 1, activated carbon and acetylene black, which are carbon materials, are dispersed in a solution in which an ammonium salt of carboxymethyl cellulose, which is a polymer resin, is dissolved in water as an electrode material, and an emulsion of polytetrafluoroethylene is further mixed. The polarizable electrode material was used.

  In Embodiment 1 of the present invention, the water content of the polarizable electrode before being applied onto the current collector 2 by the applicator 3 is 2.5.

  As the current collector 2, an aluminum etching foil having a thickness of 20 μm obtained by roughening an aluminum foil by an etching process was used. However, the type of the current collector is not particularly limited and may be a conductive foil. Any foil can be used as the current collector.

  As the applicator 3, the type of the applicator 3 is not particularly limited as long as the applicator 3 can apply the electrode material to the current collector 2 with a desired thickness, and any applicator 3 is used. be able to.

  Here, about the thickness which applies an electrode material on the electrical power collector 2, the thickness of an electrode can be determined according to a use. In the first embodiment, application was performed such that the thickness of the electrode material layer after drying was 75 μm.

  The applicator 3 may be an applicator 3 that applies electrode material to the current collector 2 one side at a time, or the applicator 3 that applies electrode material to the current collector 2 on both sides simultaneously. You may use.

  In the first embodiment, a polarizable electrode material for an electrochemical capacitor as an electrode material on a 20 μm aluminum etching foil that is a current collector 2, and a polarizable electrode for an electrochemical capacitor as an electrode, A die coater was used as the applicator 3 so that the thickness after drying of the polarizable electrode material layer was 75 μm, and coating was performed on one side.

  An electrode is obtained by drying the electrode material applied by the coating machine 3 on the current collector 2 by the drying device 4. Desirably, the drying device 4 for drying the electrode material coated on the current collector 2 by the coating machine 3 has two or more drying chambers 11 capable of independently controlling the drying conditions.

  At this time, if the drying apparatus 4 having two or more drying chambers 11 capable of independently controlling the drying conditions is used, the moisture content of the electrode material applied on the current collector 2 is the critical moisture content. The initial drying until it becomes can be performed in a short time. Alternatively, finish drying can be performed in a short time when the moisture content of the electrode material applied on the current collector 2 is equal to or lower than the limit moisture content.

  Moreover, the drying apparatus 4 for drying the electrode material applied on the current collector 2 by the coating machine 3 has three or more drying chambers 11 capable of independently controlling the drying conditions. More desirable.

  At this time, if the drying apparatus 4 having three or more drying chambers 11 capable of independently controlling the drying conditions is used, the moisture content of the electrode material applied on the current collector 2 is the critical moisture content. The initial drying to be performed can be performed in a short time, and the evaporation rate of the solvent from the surface of the electrode material during the period in which the moisture content of the electrode material is near the limit moisture content, the diffusion rate of the solvent in the electrode By drying the electrode material under the following drying conditions, it is possible to obtain an electrode that is soft, has no cracks or peeling, has a smooth surface, and is further dried to a desired residual moisture content. It can be done in a short time.

  Here, the drying conditions of the dryer provided in the drying device 4 for drying the electrode material applied on the current collector 2 by the applicator 3 will be described.

  First, drying in the case where the drying device 4 for drying the electrode material applied on the current collector 2 by the applicator 3 has two drying chambers 11 capable of independently controlling the drying conditions. A method will be described.

  In the drying apparatus 4 having two drying chambers 11 capable of independently controlling the drying conditions, in the first drying chamber 11a, the electrode material applied on the current collector 2 by the applicator 3 is used. It is desirable to perform drying for a period of time until the moisture content is 150% or less of the critical moisture content.

  In addition, the type of dryer used at that time is at least one of a dryer using a mechanism based on conduction heat transfer, a dryer using a mechanism based on convection heat transfer, and a dryer using a mechanism based on radiant heat transfer. More than one dryer can be used. In Embodiment 1 of the present invention, drying was performed in the first drying chamber 11a for a period until the moisture content of the electrode material reached 110% of the critical moisture content.

  In the first drying chamber 11a, the electrode material applied on the current collector 2 by the applicator 3 is dried for a period until the moisture content is 150% or less of the limit water content. It is desirable to increase the heat transfer rate applied per unit area of the electrode material as much as possible.

  Increasing the heat transfer rate per unit area of the electrode material as much as possible with respect to the electrode material on the current collector 2 depends on the type of the electrode material used, but the appropriate temperature and air volume are added to the electrode material. It shows that the heat transfer rate given per unit area of the electrode material is increased by the high temperature and large air volume within the range where the temperature and the air volume do not affect the characteristics of the electrode.

  By increasing the heat transfer rate given per unit area of the electrode material as much as possible, initial drying until the moisture content of the electrode material applied on the current collector 2 falls within the range of 150% or less of the limit moisture content is performed. It can be done in a short time.

  In the drying apparatus 4 having two drying chambers 11 that can control the drying conditions independently, the second drying chamber 11b has the electrode material applied on the current collector 2 by the applicator 3. It is desirable to perform drying for a period until the moisture content reaches a desired residual moisture content from a range of 150% or less of the critical moisture content.

  The type of dryer used at that time is at least one of a dryer using a mechanism based on conduction heat transfer, a dryer using a mechanism based on convection heat transfer, and a dryer using a mechanism based on radiation heat transfer. The dryer can be used.

  In the second drying chamber 11b, it is more desirable to dry the period in which the moisture content of the electrode material is the critical moisture content. In Embodiment 1, in the second drying chamber 11b, drying was performed for a period from 110% of the moisture content of the electrode material to 110% of the critical moisture content until the residual moisture content of the electrode material reached 2%.

  In the second drying chamber 11b, when drying is performed with a dryer having a mechanism of conduction heat transfer and convection heat transfer, the temperature is preferably set to 100 ° C. or lower, but 80 ° C. or lower. If so, an electrode that is soft and free from cracks and peeling and has a smooth surface can be obtained, which is further desirable.

  In the second drying chamber 11b, the temperature is not particularly limited when drying is performed only by a dryer having a radiant heat transfer mechanism.

  Further, in the second drying chamber, the current collector is collected during a period from when the moisture content of the electrode material applied to the current collector 2 by the applicator 3 becomes 150% or less of the limit moisture content to a desired residual moisture content. The heat transfer rate given per unit area of the electrode material to the electrode material on the body 2 is the evaporation rate of the solvent in the electrode material on the surface of the electrode material applied on the current collector 2. It is desirable to set it so as to be lower than the diffusion rate of the solvent.

  The heat transfer rate given to the electrode material on the current collector 2 per unit area of the electrode material is such that the evaporation rate of the solvent in the electrode material on the surface of the electrode material is less than the diffusion rate of the solvent in the electrode material. By drying the electrode material applied on the current collector 2 under the drying conditions set so as to be, it is possible to obtain an electrode that is soft, has no cracks or peeling, and has a smooth surface.

  Here, the drying apparatus 4 used in Embodiment 1 of the present invention will be described. In the first embodiment, an electrode material for an electrochemical capacitor that is an electrode material applied by a die coater that is a coating machine 3 on an aluminum etching foil obtained by roughening aluminum as a current collector 2 by an etching process. The drying apparatus 4 for drying used the coating apparatus 1 which has the two drying chambers 11 which can control drying conditions independently.

  Further, in the first drying chamber 11a according to the first embodiment, a hot air dryer that blows hot air in a direction opposite to the traveling direction of the current collector 2 and an electrode on the current collector 2 by an applicator 3 A hot air drier that applies hot air to the current collector 2 at a right angle from a surface opposite to the surface on which the material is applied is provided.

  Furthermore, hot air is applied to the second drying chamber 11b in the first embodiment at a right angle from the surface of the current collector 2 on which the electrode material is applied by the applicator 3 and from both sides of the opposite surface. The hot air dryer which supports 2 with a hot air is provided.

  Here, as for the heat transfer rate, it is desirable to obtain the heat transfer rate per unit area of the electrode material applied on the current collector 2, but actually the heat transfer rate per unit area of the electrode material is measured. Since this is difficult, in Embodiment 1, the heat transfer rate per unit area supplied by the dryer is calculated.

Specific drying conditions of the dryer used in Embodiment 1 will be described. The hot air dryer in the first drying chamber 11a includes a hot air dryer that blows hot air in a direction opposite to the traveling direction of the current collector 2, and an electrode material on the current collector 2 by an applicator 3. Both of the hot air dryers that apply hot air to the current collector 2 at a right angle from the surface opposite to the surface on which the material is applied are both devices that are twice the application width of the electrode material applied on the current collector 2 The electrode material was heated by hot air having a width of 80 ° C. and a wind speed of 1 m / s. The heat transfer rate supplied per unit area by the hot air dryer determined by calculation is 2500 J / (m ² · s).

Further, the hot air dryer in the second drying chamber 11b has a device width that is twice the coating width of the electrode material coated on the current collector 2, and the temperature of the hot air dryer is 50 ° C. The electrode material was heated by hot air with a wind speed of 1 m / s. The heat transfer rate supplied per unit area by the hot air dryer determined by calculation is 1200 J / (m ² · s).

  Here, the critical moisture content will be described.

  In the case of drying an electrode material at a constant heat transfer rate, it is generally known that there are three drying periods: a preheating period, a constant rate drying period, and a reduced rate drying period. And when the moisture content of an electrode material reaches a limit moisture content, it is known that it shifts from a constant rate drying period to a decreasing rate drying period.

  Further, various phenomena observed before and after the limit moisture content caused by shifting from the constant rate drying period to the decreasing rate drying period when the moisture content of the electrode material reaches the limit moisture content will be described.

  First, when the moisture content of the electrode material is higher than the limit moisture content, the evaporation rate of the solvent on the electrode material surface is slower than the diffusion rate of the solvent in the electrode material in the electrode material, and the surface of the electrode material Drying proceeds in an evaporation-controlled state, and the surface of the electrode material is in a wet state. Further, when the moisture content of the electrode material is higher than the limit moisture content, the surface temperature of the electrode material is kept at a constant temperature substantially equal to the wet bulb temperature of air.

  Next, when the moisture content of the electrode material is lower than the limit moisture content, the diffusion rate of the solvent in the electrode material is slower than the evaporation rate of the solvent on the surface of the electrode material in the electrode material. Since the drying is progressing in a state where the internal diffusion rate of the solvent is controlled, the speed of the solvent movement from the inside of the electrode material cannot keep up with the evaporation rate on the surface of the material, so the surface of the electrode material is visually dry It is. Further, when the moisture content of the electrode material is lower than the limit moisture content, the surface temperature of the electrode material gradually increases.

  Therefore, in the drying step, the moisture content of the electrode material at the time when the diffusion rate of the solvent in the electrode material on almost the entire surface of the electrode material becomes smaller than the evaporation rate of the solvent from the free water surface is defined as the critical moisture content.

  Here, how to determine the critical moisture content of the electrode material applied on the current collector 2 will be described. As a method for determining the limit moisture content of the electrode material, the drying rate of the electrode material is continuously measured, and the moisture content at the time when the drying rate starts to decrease can be set as the limit moisture content.

  In addition, the surface temperature of the electrode material can be continuously measured, the moisture content at the time when the surface temperature of the electrode material begins to rise can be the limit moisture content, the glossiness of the electrode material surface can be continuously measured, The moisture content at the time when the glossiness of the electrode material surface starts to change can be made the critical moisture content.

  Furthermore, as a simple method, by touching the surface of the electrode material, it can be determined whether the surface of the electrode material is dry or not, and the moisture content at the time of starting to dry can be set as the limit moisture content.

  However, it is not particularly limited as to how to determine the critical moisture content, and it can be confirmed that the drying period of the electrode material has shifted from the constant rate drying period to the reduced rate drying period. Any method for determining the limit moisture content by any other method can be used.

  Here, the limit moisture content of the electrode material for the electrochemical capacitor used in the first embodiment is 1.5, and the moisture content of the electrode material is 110% of the limit moisture content in the first drying chamber 11a. It dried to 1.65 and it dried so that the residual moisture content of an electrode material might be 2% in the 2nd drying chamber 11b.

(Embodiment 2)
Hereinafter, only the points different from the first embodiment will be described with reference to the drawings for the drying method after applying the electrode material to the coating apparatus and the continuously running current collector in the second embodiment of the present invention.

  In the second embodiment, an electrode material for an electrochemical capacitor, which is an electrode material applied by a die coater which is a coating machine 3 on an aluminum etching foil obtained by roughening aluminum as a current collector 2 by etching treatment, is used. The drying apparatus 4 for drying used the coating apparatus 1 which has the three drying chambers 11 which can control drying conditions independently.

  First, in the drying apparatus 4 having three drying chambers 11 capable of independently controlling the drying conditions, in the first drying chamber 11a, an electrode coated on the current collector 2 by the coating machine 3 It is desirable to perform drying for a period in which the moisture content of the material is in the range of 80% to 150% of the critical moisture content.

  In addition, the type of dryer used at that time is at least one of a dryer using a mechanism based on conduction heat transfer, a dryer using a mechanism based on convection heat transfer, and a dryer using a mechanism based on radiant heat transfer. More than one dryer can be used. In Embodiment 2, drying was performed in the first drying chamber 11a for a period until the moisture content of the electrode material reached 110% of the critical moisture content.

  In the first drying chamber 11a, the current collector is in a drying period in which the moisture content of the electrode material applied on the current collector 2 by the applicator 3 is in the range of 80% to 150% of the critical moisture content. It is desirable to increase the heat transfer rate given per unit area of the electrode material as much as possible with respect to the electrode material on 2.

  Here, with respect to the electrode material on the current collector 2, increasing the heat transfer rate given per unit area of the electrode material as much as possible varies depending on the type of the intended electrode, It shows that the heat transfer rate given per unit area of the electrode material is increased by the high temperature and the large air volume within the range in which the temperature and the air volume applied to the electrode material do not affect the characteristics of the electrode.

  Thus, by increasing the heat transfer rate given per unit area of the electrode material as much as possible, the moisture content of the electrode material applied on the current collector 2 is in the range of 80% to 150% of the limit moisture content. It is assumed that the initial drying which is the drying of can be performed in a short time.

  Further, in the drying apparatus 4 having three drying chambers 11 capable of independently controlling the drying conditions, in the second drying chamber 11b, an electrode coated on the current collector 2 by the coating machine 3 It is desirable to perform drying for a period from when the moisture content of the material reaches 80% or more and 150% or less of the critical moisture content until the moisture content becomes 95% or less of the critical moisture content.

  The type of dryer used at that time is at least one of a dryer using a mechanism based on conduction heat transfer, a dryer using a mechanism based on convection heat transfer, and a dryer using a mechanism based on radiation heat transfer. The dryer can be used.

  In the second drying chamber 11b, it is more desirable to dry a period in which the moisture content of the electrode material is the limit moisture content. In the second embodiment, drying was performed in the second drying chamber 11b until the moisture content of the electrode material reached 110% to 90% of the critical moisture content.

  In the second drying chamber 11b, the moisture content of the electrode material coated on the current collector 2 by the coating machine 3 is in the range of 80% to 150% of the critical moisture content, and the moisture content of 95% or less of the critical moisture content. In the electrode material on the surface of the electrode material applied on the current collector 2, the heat transfer rate given per unit area of the electrode material to the electrode material on the current collector 2 during the drying period until It is desirable that the evaporation rate of the solvent is set to be equal to or lower than the diffusion rate of the solvent in the electrode material.

  The heat transfer rate given to the electrode material on the current collector 2 per unit area of the electrode material is such that the evaporation rate of the solvent in the electrode material on the surface of the electrode material is less than the diffusion rate of the solvent in the electrode material. Is set so that the electrode material applied on the current collector 2 is dried by the drying device 4 having three drying chambers 11 capable of independently controlling the drying conditions. An electrode having a smooth surface without cracking or peeling can be obtained.

  In the second drying chamber 11b, when drying is performed with a dryer having a mechanism of conduction heat transfer and convection heat transfer, the temperature is preferably set to 100 ° C. or lower, but 80 ° C. or lower. If so, an electrode that is soft and free from cracks and peeling and has a smooth surface can be obtained, which is further desirable.

  In the second drying chamber 11b, the temperature is not particularly limited when drying is performed only by a dryer having a radiant heat transfer mechanism.

  In the drying apparatus 4 having three drying chambers 11 capable of independently controlling the drying conditions, in the third drying chamber 11c, the electrode material applied on the current collector 2 by the applicator 3 is used. It is desirable to perform drying for a period from the moisture content of 95% or less of the critical moisture content to the desired residual moisture content.

  In addition, the type of dryer used at that time is at least one of a dryer using a mechanism based on conduction heat transfer, a dryer using a mechanism based on convection heat transfer, and a dryer using a mechanism based on radiant heat transfer. More than one dryer can be used. In Embodiment 2, in the third drying chamber 11c, drying was performed for a period from 90% of the moisture content of the electrode material to the critical moisture content until the residual moisture content of the electrode material became 2%.

  Further, in the third drying chamber 11c, the current collector is collected during a period from the moisture content of 95% or less of the moisture content of the electrode material applied on the current collector 2 by the applicator 3 to the desired residual moisture content. It is desirable to increase the heat transfer rate applied per unit area of the electrode material as much as possible with respect to the electrode material on the body 2.

  Here, with respect to the electrode material on the current collector 2, increasing the heat transfer rate given per unit area of the electrode material as much as possible varies depending on the use of the electrode. It shows that the heat transfer rate given per unit area of the electrode material is increased by applying a high temperature and a large air volume within a range where the applied temperature and the air volume do not affect the characteristics of the electrode.

  In this way, by increasing the heat transfer rate given per unit area of the electrode material as much as possible, the moisture content of the electrode material applied on the current collector 2 is reduced to a desired moisture content from 95% or less of the critical moisture content. Finish drying until the residual moisture content is achieved can be performed in a short time.

  In the second embodiment, the coating apparatus 1 having the drying apparatus 4 in which the lengths of the three drying chambers 11 that can independently control the drying conditions are equal to each other is used.

  In the first drying chamber 11a in the second embodiment, electrode material is applied to the hot air dryer that blows hot air in the direction opposite to the traveling direction of the current collector 2 and the applicator 3 on the current collector 2. A hot air dryer is provided that applies hot air to the current collector 2 at a right angle from the surface opposite to the coated surface.

  In the second drying chamber 11b in the second embodiment, hot air is applied at right angles from the surface of the current collector 2 on which the electrode material is applied by the applicator 3 and from both sides of the opposite surface. A hot air dryer supported by hot air is provided.

  In the third drying chamber 11c according to the second embodiment, hot air is applied at right angles from the surface of the current collector 2 on which the electrode material is applied by the applicator 3 and from both sides of the opposite surface. A hot air dryer supported by hot air is provided.

  Here, as for the heat transfer rate, it is desirable to obtain the heat transfer rate per unit area of the electrode material applied on the current collector 2, but actually the heat transfer rate per unit area of the electrode material is measured. Since this is difficult, in Embodiment 2, the heat transfer rate supplied by the dryer is determined by calculation.

Here, the specific drying conditions of the dryer used in Embodiment 2 will be described. In the first drying chamber 11a, a hot air dryer that blows hot air in a direction opposite to the traveling direction of the current collector 2, and a surface on which the electrode material is applied on the current collector 2 by the applicator 3 Is provided with a hot air dryer that applies hot air to the current collector 2 at a right angle from the opposite surface, and both have a device width that is twice the coating width of the electrode material applied on the current collector 2. In these hot air dryers, heat was applied to the electrode material by hot air at a temperature of 80 ° C. and a wind speed of 1 m / s. The heat transfer rate supplied per unit area by the hot air dryer determined by calculation is 2500 J / (m ² · s).

Further, the hot air dryer in the second drying chamber 11b has a device width that is twice the coating width of the electrode material coated on the current collector 2, and the temperature of the hot air dryer is 50 ° C. The electrode material was heated by hot air with a wind speed of 1 m / s. The heat transfer rate supplied per unit area by the hot air dryer determined by calculation is 1200 J / (m ² · s).

Further, the hot air dryer in the third drying chamber 11c has a device width twice that of the electrode material applied on the current collector 2, and the temperature of the hot air dryer is 80 ° C. The electrode material was heated by hot air with a wind speed of 2 m / s. The heat transfer rate supplied per unit area by the hot air dryer determined by calculation is 4500 J / (m ² · s).

  Here, the limit moisture content of the electrode material for an electrochemical capacitor used in the second embodiment is 1.5, and the moisture content of the electrode material is 110% of the limit moisture content in the first drying chamber 11a. It is dried to 1.65, the moisture content of the electrode material is dried to 1.35 which is 90% of the limit moisture content in the second drying chamber 11b, and the residual moisture content of the electrode material is 2 in the third drying chamber 11c. It dried so that it might become%.

(Embodiment 3)
Hereinafter, with respect to the application method and the drying method after applying the electrode material to the continuously running current collector in the third embodiment of the present invention, only the differences from the first and second embodiments will be described with reference to the drawings. While explaining.

  In the third embodiment, the electrode material for an electrochemical capacitor, which is an electrode material applied by a die coater that is a coating machine 3, is dried on an aluminum etching foil that has been roughened by etching the aluminum that is the current collector 2. The coating device 1 having three drying chambers 11 that can independently control the drying conditions was used as the drying device 4 for the purpose.

  In the third embodiment, the length of the drying chamber 11 capable of independently controlling the drying conditions is the length of the first drying chamber 11a is 1/2 that of the drying device 4, and the second drying. The coating apparatus 1 having the drying apparatus 4 in which the length of the chamber 11b is 1/4 of the drying apparatus 4 and the length of the third drying chamber 11c is 1/4 of the drying apparatus 4 was used. .

  In the first drying chamber 11 a according to the third embodiment, an electrode material is applied to the hot air dryer that blows hot air in the direction opposite to the traveling direction of the current collector 2 and the applicator 3 on the current collector 2. A hot air dryer that applies hot air to the current collector 2 at a right angle from a surface opposite to the coated surface, and an infrared dryer above the current collector 2 are provided.

  In the second drying chamber 11b in the third embodiment, hot air is applied at right angles from the surface of the current collector 2 on which the electrode material is applied by the applicator 3 and from both sides of the opposite surface. A hot air dryer supported by hot air is provided.

  In the third drying chamber 11c in the third embodiment, hot air is applied at right angles from the surface of the current collector 2 on which the electrode material is applied by the applicator 3 and from both sides of the opposite surface. A hot air dryer supported by hot air and an infrared dryer above the current collector 2 are provided.

  Here, as for the heat transfer rate, it is desirable to obtain the heat transfer rate per unit area of the electrode material applied on the current collector 2, but actually the heat transfer rate per unit area of the electrode material is measured. Since this is difficult, in Embodiment 3, the heat transfer rate supplied by the dryer is determined by calculation.

Here, the specific drying conditions of the dryer used in Embodiment 3 will be described. In the first drying chamber 11a, a hot air dryer that blows hot air in a direction opposite to the traveling direction of the current collector 2, and a surface on which the electrode material is applied on the current collector 2 by the applicator 3 Are provided with a hot-air dryer that applies hot air to the current collector 2 at a right angle from the opposite side, and an infrared dryer above the current collector 2, both of which are coated on the current collector 2. The device width is twice as large as the applied width of the electrode material. With these hot air dryers, hot air having a temperature of 80 ° C. and a wind speed of 1 m / s is applied to the current collector 2, and an infrared dryer is 350 Heat was applied to the electrode material by heating to ° C. The heat transfer rate supplied per unit area of the hot air dryer and infrared dryer determined by calculation is 10000 J / (m ² · s).

Further, the hot air dryer in the second drying chamber 11b has a device width that is twice the coating width of the electrode material coated on the current collector 2, and the temperature of the hot air dryer is 50 ° C. The electrode material was heated by hot air with a wind speed of 1 m / s. The heat transfer rate supplied per unit area by the hot air dryer determined by calculation is 1200 J / (m ² · s).

Further, the hot air dryer in the third drying chamber 11c and the infrared dryer provided above the current collector 2 have a device width that is twice the application width of the electrode material applied on the current collector 2. In the hot air dryer, heat was applied to the electrode material by applying hot air at a temperature of 80 ° C. and a wind speed of 2 m / s to the current collector 2 and heating the infrared dryer to 350 ° C. . The heat transfer rate supplied per unit area in combination of the hot air dryer and infrared dryer determined by calculation is 13000 J / (m ² · s).

  Here, the limit moisture content of the electrode material for an electrochemical capacitor used in the third embodiment is 1.5, and the moisture content of the electrode material is 110% of the limit moisture content in the first drying chamber 11a. It is dried to 1.65, the moisture content of the electrode material is dried to 1.35 which is 90% of the limit moisture content in the second drying chamber 11b, and the residual moisture content of the electrode material is 2 in the third drying chamber 11c. It dried so that it might become%.

(Embodiment 4)
Hereinafter, with respect to the application method and the drying method after applying the electrode material to the continuously running current collector in the fourth embodiment of the present invention, the differences from the first embodiment, the second embodiment, and the third embodiment Only will be described with reference to the drawings.

  In the fourth embodiment, the electrode material for an electrochemical capacitor, which is an electrode material applied by a die coater, which is a coating machine 3, is dried on an aluminum etching foil obtained by roughening the aluminum, which is the current collector 2, by an etching process. The coating device 1 having 6 drying chambers 11 that can independently control the drying conditions was used as the drying device 4 for the purpose.

  Further, in the fourth embodiment, the coating apparatus 1 having the drying apparatus 4 in which the lengths of the six drying chambers 11 capable of independently controlling the drying conditions are equal to each other is used.

  Here, when the drying device 4 for drying the electrode material applied on the current collector 2 by the applicator 3 has four or more drying chambers 11 capable of independently controlling the drying conditions. Will be described.

  First, how to separate the drying zones in the drying apparatus 4 having four or more drying chambers 11 capable of independently controlling the drying conditions will be described. First, the first drying zone is a drying chamber 11 continuous from the first drying chamber 11a, and the heat transfer rate per unit area of the electrode material with respect to the electrode material coated on the current collector 2 is high. This is an aggregate of the drying chamber 11 that is equal to or higher than the heat transfer rate per unit area given to the electrode material in the previous drying chamber 11.

  The second drying zone is a drying chamber 11 that is continuous from the final drying chamber 11 of the first drying zone, and per unit area of the electrode material with respect to the electrode material applied on the current collector 2. The continuous heat transfer rate applied to the electrode material in the final drying chamber 11 of the first drying zone is the heat transfer rate per unit area or less given to the electrode material. The heat transfer rate per unit area given to is an aggregate of drying chambers 11 that is equal to or lower than the heat transfer rate per unit area given to the electrode material in the previous drying chamber 11.

  Further, the third drying zone is a drying chamber 11 continuous from the final drying chamber 11 of the second drying zone, and the heat transfer rate per unit area given to the electrode material applied on the current collector 2 Is the aggregate of all the drying chambers 11 after the drying chamber 11 in the final drying chamber 11 of the second drying zone, which is equal to or higher than the heat transfer rate per unit area given to the electrode material.

  In addition, about the drying chamber 11 of the 1st drying zone, the heat transfer rate per unit area given to the electrode material apply | coated on the electrical power collector 2 is an electrode material in the drying chamber 11 in front one intermittently. Even if the drying chamber 11 having a heat transfer rate per unit area or less given to the electrode material is included, the heat transfer rate per unit area given to the electrode material is the electrode in the previous drying chamber 11 after the drying chamber 11. A drying chamber 11 having a heat transfer rate per unit area or more given to the material is provided. In the drying chamber 11 or the subsequent drying chamber 11, the heat transfer rate per unit area given to the electrode material is one. When the drying chamber 11 having a heat transfer rate per unit area or more applied to the electrode material in the previous drying chamber 11 is continuous, the electrode after the drying in the final drying chamber 11 of the continuous drying chamber 11 is completed. The moisture content of the material is the limit If the water content is in the range of 80% to 150%, the first drying chamber 11a to the drying chamber 11 where the moisture content of the electrode material is dried to the range of 80% to 150% of the critical moisture content is the first. Can be defined as the drying zone.

  Moreover, about the drying chamber 11 of a 2nd drying zone, the heat transfer rate per unit area given to the electrode material apply | coated on the electrical power collector 2 is intermittent in the drying chamber 11 in the immediately preceding one in the electrode material. Even if the drying chamber 11 is higher than the heat transfer rate per unit area given to the electrode, the heat transfer rate per unit area given to the electrode material is the electrode in the previous drying chamber 11 after the drying chamber 11. A drying chamber 11 that is equal to or lower than the heat transfer rate per unit area given to the material is provided. In the drying chamber 11 or the subsequent drying chamber 11, the heat transfer rate per unit area given to the electrode material is one. When the drying chamber 11 that is equal to or lower than the heat transfer rate per unit area given to the electrode material in the previous drying chamber 11 is continuous, the electrode after completion of drying in the final drying chamber 11 of the continuous drying chamber 11 The moisture content of the material is the limit If the water content is 95% or less, drying is performed so that the moisture content of the electrode material is dried to 95% or less of the critical moisture content from the last drying chamber 11 continuous with the final drying chamber 11 in the first drying zone. Up to chamber 11 can be defined as the second drying zone.

  Then, when the drying device 4 for drying the electrode material applied on the current collector 2 by the coating machine 3 has four or more drying chambers 11 capable of independently controlling the drying conditions. A drying method will be described.

  First, in the drying apparatus 4 that has four or more drying chambers 11 that can independently control the drying conditions and can be divided into three drying zones, the current collection is performed in the first drying zone. It is desirable to perform drying for a period until the moisture content of the electrode material coated on the body 2 by the coating machine 3 is in the range of 80% to 150% of the critical moisture content.

  In addition, the type of dryer used at that time is at least one of a dryer using a mechanism based on conduction heat transfer, a dryer using a mechanism based on convection heat transfer, and a dryer using a mechanism based on radiant heat transfer. More than one dryer can be used. In Embodiment 4, drying was performed in the first drying zone until the moisture content of the electrode material reached 110% of the critical moisture content.

  In the first drying zone, the current collector 2 is in a drying period in which the moisture content of the electrode material applied on the current collector 2 by the applicator 3 is in the range of 80% to 150% of the critical moisture content. It is desirable to increase the heat transfer rate given per unit area of the electrode material as much as possible with respect to the upper electrode material.

  Here, with respect to the electrode material on the current collector 2, increasing the heat transfer rate given per unit area of the electrode material as much as possible varies depending on the use of the electrode. It shows that the heat transfer rate given per unit area of the electrode material is increased by applying a high temperature and a large air volume within a range where the applied temperature and the air volume do not affect the characteristics of the electrode.

  Thus, by increasing the heat transfer rate given per unit area of the electrode material as much as possible, the moisture content of the electrode material applied on the current collector 2 is in the range of 80% to 150% of the limit moisture content. It is assumed that the initial drying can be performed in a short time.

  In addition, in the drying apparatus 4 that has four or more drying chambers 11 that can independently control the drying conditions and can be divided into three drying zones, the current collection is performed in the second drying zone. The electrode material applied on the body 2 by the applicator 3 may be dried for a period from the range of 80% to 150% of the critical moisture content to the moisture content of 95% or less of the critical moisture content. desirable.

  The type of dryer used at that time is at least one of a dryer using a mechanism based on conduction heat transfer, a dryer using a mechanism based on convection heat transfer, and a dryer using a mechanism based on radiation heat transfer. The dryer can be used. Further, it is further desirable to dry the period in which the moisture content of the electrode material is the critical moisture content in the second drying zone. In Embodiment 4, drying was performed in the second drying zone for a period until the moisture content of the electrode material reached 110% to 90% of the critical moisture content.

  In the second drying zone, the moisture content of the electrode material coated on the current collector 2 by the coating machine 3 is in the range of 80% to 150% of the critical moisture content, and the moisture content of 95% or less of the critical moisture content. The heat transfer rate given per unit area of the electrode material with respect to the electrode material on the current collector 2 during the drying period until the rate reaches is the electrode material on the surface of the electrode material applied on the current collector 2 It is desirable to set the evaporation rate of the solvent therein to be equal to or lower than the diffusion rate of the solvent in the electrode material.

  Thus, the heat transfer rate given per unit area of the electrode material to the electrode material on the current collector 2 is the same as the evaporation rate of the solvent in the electrode material on the surface of the electrode material. If it is set to be lower than the diffusion rate, the electrode material applied on the current collector 2 has four or more drying chambers 11 in which the drying conditions can be controlled independently. By drying with the drying device 4 that can be divided into zones, an electrode that is soft, has no cracks or peeling, and has a smooth surface can be obtained.

  Further, in the drying chamber 11 in the second drying zone, when drying is performed by a dryer having a mechanism of conduction heat transfer and convection heat transfer, the temperature is preferably set to 100 ° C. or less. If it is 80 degrees C or less, since it is soft, there is no crack, peeling, etc., and an electrode with the smooth surface can be obtained, it is further desirable.

  In the drying chamber 11 in the second drying zone, the temperature is not particularly limited in the drying chamber 11 where drying is performed only by a dryer having a radiant heat transfer mechanism.

  In the drying apparatus 4 that has four or more drying chambers 11 that can independently control the drying conditions and can be divided into three drying zones, the current collector 2 is provided in the third drying zone. It is desirable to perform drying for a period of time until the moisture content of the electrode material applied by the applicator 3 reaches a desired residual moisture content from a moisture content of 95% or less of the critical moisture content.

  In addition, the type of dryer used at that time is at least one of a dryer using a mechanism based on conduction heat transfer, a dryer using a mechanism based on convection heat transfer, and a dryer using a mechanism based on radiant heat transfer. More than one dryer can be used. In Embodiment 4, in the third drying zone, drying was performed for a period from 90% of the moisture content of the electrode material to the limit moisture content until the residual moisture content of the electrode material reached 2%.

  Further, in the third drying zone, the current collector is in a period from the moisture content of 95% or less of the moisture content of the electrode material applied on the current collector 2 by the applicator 3 to the desired residual moisture content. It is desirable to increase the heat transfer rate given per unit area of the electrode material as much as possible with respect to the electrode material on 2.

  Here, with respect to the electrode material on the current collector 2, increasing the heat transfer rate given per unit area of the electrode material as much as possible varies depending on the use of the electrode. It shows that the heat transfer rate given per unit area of the electrode material is increased by applying a high temperature and a large air volume within a range where the applied temperature and the air volume do not affect the characteristics of the electrode.

  In this way, by increasing the heat transfer rate given per unit area of the electrode material as much as possible, the moisture content of the electrode material applied on the current collector 2 is reduced to a desired moisture content from 95% or less of the critical moisture content. It is assumed that finish drying until the residual moisture content is achieved can be performed in a short time.

  As shown in FIG. 2, the drying apparatus 4 according to the fourth embodiment of the present invention has six drying chambers, from the first drying chamber 11a to the sixth drying chamber 11f, respectively. Is a hot air dryer that blows hot air in a direction opposite to the traveling direction of the current collector 2, and a surface opposite to the surface on which the electrode material is applied by the coating device 3 on the current collector 2, A hot air drier that applies hot air to the current collector 2 at right angles is provided.

  In addition, an electrode material is applied to the second drying chamber 11 b by a hot air dryer that blows hot air in a direction opposite to the traveling direction of the current collector 2, and an applicator 3 on the current collector 2. A hot air dryer that applies hot air at a right angle to the current collector 2 from a surface opposite to the surface of the current collector, and an infrared dryer above the current collector 2 are provided.

  In addition, hot air is applied to the third drying chamber 11c at right angles from the surface of the current collector 2 on which the electrode material is applied by the applicator 3, and from both sides of the opposite surface, and the current collector 2 is supported by the hot air. It has a hot air dryer.

  In addition, hot air is applied to the fourth drying chamber 11d at right angles from the surface of the current collector 2 on which the electrode material is applied by the applicator 3 and the opposite surface, thereby supporting the current collector 2 with hot air. It has a hot air dryer.

  Further, hot air is applied to the fifth drying chamber 11e at a right angle from the surface of the current collector 2 on which the electrode material is applied by the applicator 3 and from both sides of the opposite surface, and the current collector 2 is supported by the hot air. It has a hot air dryer.

  In addition, hot air is applied to the sixth drying chamber 11f at right angles from the surface of the current collector 2 on which the electrode material is applied by the applicator 3 and from both sides of the opposite surface, thereby supporting the current collector 2 with hot air. A hot air dryer and an infrared dryer above the current collector 2.

  In the fourth embodiment, the six drying chambers 11 are divided into the following three drying zones. First, the first drying zone is the first drying chamber 11a and the second drying chamber 11b, and the second drying zone is from the third drying chamber 11c to the fifth drying chamber 11e, The third drying zone is a sixth drying chamber 11f.

  Here, as for the heat transfer rate, it is desirable to obtain the heat transfer rate per unit area of the electrode material applied on the current collector 2, but actually the heat transfer rate per unit area of the electrode material is measured. Since this is difficult, in Embodiment 4, the heat transfer rate supplied by the dryer is determined by calculation.

Here, specific drying conditions of the dryer used in Embodiment 4 will be described. The electrode material was applied to the first drying chamber 11 a by a hot air dryer that blows hot air in a direction opposite to the traveling direction of the current collector 2, and an applicator 3 on the current collector 2. A hot air drier that applies hot air to the current collector 2 at a right angle from the surface opposite to the surface is provided, both of which are devices that are twice the application width of the electrode material applied on the current collector 2 The electrode material was heated with hot air having a width of 80 ° C. and a wind speed of 1 m / s. The heat transfer rate supplied by the hot air dryer per unit area, which is obtained by calculation, is 2500 J / (m ² · s).

The electrode material was applied to the second drying chamber 11b by a hot air dryer that blows hot air in a direction opposite to the traveling direction of the current collector 2, and a coating device 3 on the current collector 2. A hot air dryer that applies hot air to the current collector 2 at a right angle from a surface opposite to the surface, and an infrared dryer above the current collector 2 are provided on the current collector 2. The device width is twice the coating width of the coated electrode material. With these hot air dryers, hot air having a temperature of 80 ° C. and a wind speed of 2.5 m / s is applied to the current collector 2, and infrared rays are applied. The dryer was heated to 500 ° C. to give heat to the electrode material. The heat transfer rate supplied per unit area of the hot air dryer and infrared dryer determined by calculation is 24000 J / (m ² · s).

Further, the hot air dryer in the third drying chamber 11c has a device width that is twice the application width of the electrode material applied on the current collector 2, and the temperature of the hot air dryer is 50 ° C. The electrode material was heated by hot air with a wind speed of 1.5 m / s. The heat transfer rate supplied by the hot air dryer per unit area, which was obtained by calculation, is 1700 J / (m ² · s).

Further, the hot air dryer in the fourth drying chamber 11d has a device width that is twice the application width of the electrode material applied on the current collector 2, and the temperature of the hot air dryer is 50 ° C. The electrode material was heated by hot air with a wind speed of 1.2 m / s. The heat transfer rate supplied by the hot air dryer per unit area, which is obtained by calculation, is 1400 J / (m ² · s).

Further, the hot air dryer in the fifth drying chamber 11e has a device width that is twice the coating width of the electrode material applied on the current collector 2, and the hot air dryer has a temperature of 50 ° C. The electrode material was heated by hot air with a wind speed of 1 m / s. The heat transfer rate supplied by the hot air dryer per unit area, which is obtained by calculation, is 1200 J / (m ² · s).

In addition, the hot air dryer in the sixth drying chamber 11f and the infrared dryer provided above the current collector 2 have a device width that is twice the application width of the electrode material applied on the current collector 2. In the hot air dryer, heat was applied to the electrode material by applying hot air at a temperature of 80 ° C. and a wind speed of 2 m / s to the current collector 2 and heating the infrared dryer to 500 ° C. . The heat transfer rate supplied per unit area in combination of the hot air dryer and the infrared dryer determined by calculation is 23000 J / (m ² · s).

  Here, the limit moisture content of the electrode material for an electrochemical capacitor used in Embodiment 4 is 1.5, and the moisture content of the electrode material is 110% of the limit moisture content in the first drying zone. .65, the moisture content of the electrode material is dried to 1.35 which is 90% of the critical moisture content in the second drying zone, and the residual moisture content of the electrode material is 2% in the third drying zone. Drying was performed as follows.

  Here, an evaluation method, detailed apparatus conditions, and operation conditions of the obtained electrode 12 for an electrochemical capacitor in the first to fourth embodiments will be described.

  The obtained electrode 12 for an electrochemical capacitor was slid with the electrode 12 for an electrochemical capacitor by means of an adhesion evaluation device comprising a presser 13, an electrode support 14, round bars 15, 16 and a weight 17 shown in FIG. 5 and the case where no peeling or cracking occurs in the electrode 12 for the electrochemical capacitor after the evaluation, 5 for the electrochemical capacitor The case where the electrode layer was peeled from the current collector was defined as 1, and the state between them was evaluated as 2-4.

  First, Example 1 according to Embodiment 1 will be described.

Example 1
Application and drying are performed at a coating speed of 2 m / min using the coating apparatus 1 including the drying apparatus 4 in which the length of the first drying chamber 11a is 1 m and the length of the second drying chamber 11b is 4 m. went.

  Example 2 according to the second embodiment will be described.

(Example 2)
Coating and drying were performed at a coating speed of 2 m / min using the coating apparatus 1 including the drying apparatus 4 having three drying chambers 11 having a drying chamber length of 1 m.

  Example 3 according to Embodiment 3 will be described.

(Example 3)
The coating apparatus 1 provided with the drying apparatus 4 in which the length of the first drying chamber 11a is 1 m, the length of the second drying chamber 11b is 0.5 m, and the length of the third drying chamber 11c is 0.5 m. Was applied and dried at a coating speed of 2 m / min.

  Example 4 according to Embodiment 4 will be described.

Example 4
Coating and drying were performed at a coating speed of 2 m / min using the coating apparatus 1 including the drying apparatus 4 having six drying chambers 11 with the length of the drying chamber 11 being 0.3 m.

(Conventional example 1)
Coating and drying were performed at a coating speed of 2 m / min using the coating apparatus 1 including the drying apparatus 4 having three drying chambers 11 with the length of the drying chamber 11 being 0.7 m.

In the first drying chamber 11a, an electrode material is applied by a hot air dryer for blowing hot air in a direction opposite to the traveling direction of the current collector 2 and an applicator 3 on the current collector 2. A hot air dryer that applies hot air to the current collector 2 at a right angle from the surface opposite to the opposite surface, both of which are twice the coating width of the electrode material applied on the current collector 2 The electrode material was heated with hot air at a temperature of 80 ° C. and a wind speed of 2 m / s. The heat transfer rate supplied by the hot air dryer per unit area, calculated by calculation, is 4500 J / (m ² · s).

Further, in the second drying chamber 11b, hot air is applied at right angles from the surface of the current collector 2 on which the electrode material is applied by the applicator 3 and from both sides of the opposite surface, and the current collector 2 is heated by hot air. A supporting hot air dryer is provided, and the hot air dryer has a device width that is twice the application width of the electrode material applied on the current collector 2, and has a temperature of 90 ° C. and a wind speed of 2 m / second. The amount of heat was given to the electrode material by hot air of s. The heat transfer rate supplied by the hot air dryer per unit area, which is obtained by calculation, is 5400 J / (m ² · s).

Further, in the third drying chamber 11c, hot air is applied at right angles from the surface of the current collector 2 on which the electrode material is applied by the applicator 3, and from both sides of the opposite surface, and the current collector 2 is heated by hot air. A supporting hot air dryer is provided. The hot air dryer has a device width that is twice the coating width of the electrode material coated on the current collector 2, and has a temperature of 100 ° C. and a wind speed of 2 m / second. The amount of heat was given to the electrode material by hot air of s. The heat transfer rate supplied by the hot air dryer per unit area, calculated by calculation, is 6200 J / (m ² · s).

  Here, the limiting moisture content of the electrode material for an electrochemical capacitor used in Conventional Example 1 is 1.5, and the moisture content of the electrode material in the first drying chamber is 1.65 which is 110% of the limiting moisture content. Dry, dry in the second drying chamber to 0.9%, which is 60% of the critical moisture content, and dry in the third drying chamber so that the residual moisture content of the electrode material is 2%. Went.

  In the following (Table 1), the evaluation result of the adhesiveness of the electrode for electrochemical capacitors produced by these Examples 1 to 4 and Conventional Example 1 is shown.

  Examples 1 to 4 which are examples of the present invention and Conventional Example 1 are compared based on the results shown in Table 1.

  When the adhesion of the electrode for an electrochemical capacitor produced by Examples 1 to 4 and the adhesion of an electrode for an electrochemical capacitor produced by Conventional Example 1 are compared, it is apparent that the electrodes are produced by Examples 1 to 4. The electrode for the electrochemical capacitor is better in adhesion.

  This is because, when the moisture content of the electrode material for the electrochemical capacitor is 1.5, which is the critical moisture content, the heat transfer rate applied to the electrode for the electrochemical capacitor was low, so the surface of the electrode for the electrochemical capacitor was This is because the evaporation rate of water was slower than the diffusion rate of water inside the electrode for the electrochemical capacitor, so that the inside of the electrode for the electrochemical capacitor was uniformly dried.

  Next, Examples 1 to 4 which are examples of the present invention will be compared from the results shown in (Table 1).

  When Example 1 is compared with Examples 2 to 4, Example 2 to Example 4 are shorter in length than the example 1 and the drying time is shorter. In Example 2 to Example 4, since there are three or more drying chambers, in order to perform drying near the limit moisture content of the moisture content of the electrode material for the electrochemical capacitor, the heat transfer rate is increased. The drying time for finishing can be shortened by providing the third drying chamber or the third drying zone with a higher heat transfer rate after the reduced second drying chamber or the second drying zone. It is due to that.

  When Example 2 is compared with Example 3 and Example 4, Example 3 and Example 4 have a shorter overall drying apparatus and a shorter drying time than Example 2. In Example 3 and Example 4, an infrared dryer, which is a dryer using a radiant heat transfer mechanism, is used in the first drying chamber or the first drying zone and the third drying chamber or the third drying zone. This is because the initial drying time and the finishing drying time can be shortened.

  When Example 3 and Example 4 are compared, Example 4 has a shorter overall drying apparatus length and drying time than Example 3. This is because Example 4 has a larger number of drying chambers than Example 3, so that the drying conditions can be set more finely.

  If the coating apparatus and the drying method after application of the electrode material of the present invention are performed, there is an effect that it is possible to obtain an electrode that is soft, free of cracks and peeling, and has a smooth surface by drying in a short time. By using the electrode obtained by the above, it is possible to prevent occurrence of troubles in the post-process and obtain an electrochemical element having good characteristics, which is useful.

Schematic of a coating apparatus in an embodiment of the present invention Schematic of a coating apparatus in an embodiment of the present invention Schematic of electrode adhesion evaluation device for electrochemical capacitors

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Application | coating apparatus 2 Current collector 3 Application | coating machine 4 Drying apparatus 5 Unwinding roll 6 Winding roll 7 Backup roll 8, 9, 10 Roll 11 Drying chamber 11a 1st drying chamber 11b 2nd drying chamber 11c 3rd drying Chamber 11d Fourth drying chamber 11e Fifth drying chamber 11f Sixth drying chamber 11x Final drying chamber 12 Electrode 13 Presser 14 Electrode support base 15, 16 Round bar 17 Weight

Claims (6)

In the method for producing an electrochemical element, comprising: an application step of applying an electrode material onto a current collector made of a metal foil; and a drying step of drying the current collector applied with the electrode material in a drying chamber. The drying process is performed until the diffusion rate in the electrode material on almost the entire surface of the electrode material reaches a limit moisture content that is the moisture content of the electrode material at a time when the rate of water evaporation from the free water surface becomes smaller. An electrode body for an electrochemical device comprising: a first drying step for drying; and a second drying step for drying the subsequent drying step, wherein the first drying step has a higher heat transfer rate than the second drying step. Manufacturing method. In the method for producing an electrochemical element, comprising: an application step of applying an electrode material onto a current collector made of a metal foil; and a drying step of drying the current collector applied with the electrode material in a drying chamber. The drying step is a period of time until the diffusion rate in the electrode material on almost the entire surface of the electrode material reaches a limit moisture content that is the moisture content of the electrode material at a time point when the evaporation rate of water from the free water surface becomes smaller. A first drying step for drying, a second drying step for drying the subsequent drying step, and a third drying step following the second drying step, wherein the first drying step and the third drying step are the second drying step. The manufacturing method of the electrode body for electrochemical elements characterized by the heat transfer rate being higher than a drying process. An electrode body for an electrochemical device having an application part for applying an electrode material on a current collector made of metal foil, and a drying part for drying the current collector applied with the electrode material in a plurality of drying parts In the manufacturing apparatus, the drying chamber has a limit moisture content that is a moisture content of the electrode material when a diffusion rate in the electrode material on almost the entire surface of the electrode material is smaller than a water evaporation rate from a free water surface. A first drying chamber for drying until reaching the second drying chamber, and a second drying chamber for drying thereafter, and the heat transfer rate applied to the electrode material in the first drying chamber is the electrode in the second drying chamber. An apparatus for producing an electrode body for an electrochemical element, characterized in that it has a higher heat transfer rate applied to the material. The length of the said 1st drying chamber is the manufacturing apparatus of the electrode body for electrochemical elements of Claim 3 which is 1/10 or more with respect to the length of all the drying chambers. An electrode body for an electrochemical device having an application part for applying an electrode material on a current collector made of metal foil, and a drying part for drying the current collector applied with the electrode material in a plurality of drying chambers In the manufacturing apparatus, the drying chamber has a limit moisture content that is a moisture content of the electrode material when a diffusion rate in the electrode material on almost the entire surface of the electrode material is smaller than a water evaporation rate from a free water surface. A first drying chamber for drying until reaching the second drying chamber, a second drying chamber for performing subsequent drying, and a third drying chamber following the second drying chamber, wherein the first drying chamber and the third drying chamber The apparatus for manufacturing an electrode body for an electrochemical element, wherein a heat transfer rate given to the electrode material in the chamber is higher than a heat transfer rate given to the electrode material in the second drying chamber. The length of the first drying chamber is 1/10 or more with respect to the length of all drying chambers, and the length of the second drying chamber is 4/5 or less with respect to the length of all drying chambers. 6. The apparatus for producing an electrode body for an electrochemical element according to claim 5, wherein the length of the third drying chamber is 1/10 or more of the length of all the drying chambers.

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