JP2013089573A - Electrode, electrode manufacturing device, and electrode manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode, having a sufficiently close contact state between a collector and an electrode layer, and capable of maintaining electrode performance even after repetition of charging and discharging, and to provide an electrode manufacturing device and an electrode manufacturing method.SOLUTION: Electrodes 100 and 200 are formed by overlapping collectors 101 and 201 with electrode layers 103 and 203, wherein a region of the electrode layers 103 and 203 on a side where the collectors 101 and 201 overlap has component concentration of binding materials 112 and 212 contained in the electrode layers 103 and 203 higher than that of a region on a surface layer side opposite to a side where the collectors 101 and 201 overlap.

Description

  The present invention relates to an electrode, an electrode manufacturing apparatus, and an electrode manufacturing method.

  Lithium ion secondary batteries are widely used as power sources for automobiles and home appliances because they have a high storage density and maintain good storage performance even after repeated charging and discharging.

  In the process of forming an electrode of a lithium ion secondary battery, first, an electrode slurry containing an active material, a binder, a conductivity-imparting agent, and a solvent on a current collector such as a positive electrode aluminum foil or a negative electrode copper foil. Apply a constant weight. Next, in the drying furnace, the solvent contained in the electrode slurry is evaporated and dried, and the electrode layer, which is the solid content of the electrode slurry, and the current collector are fixed by a binder. After that, if necessary, the current collector with the electrode layer overlapping is pressed, the pressed current collector is cut into a predetermined size as necessary, and an electrode with the electrode layer overlapping with the current collector is manufactured. ing.

  In the step of drying the electrode, a method of blowing hot air from the upper and lower surfaces of the current collector in a drying furnace is common. The main drying conditions in the case of hot air include the temperature of hot air, the amount of hot air blown out, and the drying time. Conventionally, a drying method is known in which drying conditions are set (for example, Patent Document 1). reference).

JP 2006-107780 A

  When drying the above electrode slurry, if the drying conditions (the temperature of hot air in the case of hot air and the amount of hot air blown out) are changed greatly, the fine structure inside the electrode layer will be affected, and the electrode performance will deteriorate. There is. This is because when the temperature of the hot air is increased or the amount of hot air is increased, the binder component in the electrode slurry moves from the deep part of the electrode layer to the surface of the electrode layer (hereinafter sometimes referred to as segregation). ), Due to the absence of a sufficient binder component between the current collector and the electrode layer. In the drying method described in Patent Document 1, there is a possibility that an electrode that causes a decrease in electrode performance is produced for the above reason.

  The present invention has been made in order to solve the above-mentioned problems, and the electrode and the electrode manufacturing can maintain the electrode performance even when the current collector and the electrode layer have a sufficiently close contact state and are repeatedly charged and discharged. An object is to provide an apparatus and an electrode manufacturing method.

  The electrode according to the present invention for achieving the above object is an electrode in which an electrode layer overlaps with a current collector, and a region of the electrode layer on a side where the current collector overlaps is a surface layer side opposite to the side on which the current collector overlaps This is an electrode having a higher component concentration of the binder contained in the electrode layer than in the region.

  In the case of the electrode configured as described above, the adhesion strength between the current collector and the electrode layer is improved in the region of the electrode layer on the side where the current collector overlaps because the component concentration of the binder is high. For this reason, not only the resistance value in the battery in the initial stage of use but also the resistance value in the battery after repeated charging and discharging can be kept low, and the electrode performance can be maintained. In addition, even if the electrolyte solution soaks and the electrode layer swells, the electrode layer is not peeled off from the current collector due to the high adhesion strength between the current collector and the electrode layer. Therefore, the electrode performance can be maintained.

It is a schematic block diagram which shows the electrode manufacturing apparatus which concerns on this invention. It is a schematic diagram which shows the state change of the electrode slurry of a positive electrode when the coating layer is dried with the drying method of this embodiment, (a) is after a preheating process end, (b) is after a constant rate evaporation process end, (C) has each shown the state of the electrode slurry after the reduction process. It is a schematic diagram which shows the state change of the electrode slurry of a negative electrode when the application layer is dried with the drying method of this embodiment, (a) is after completion | finish of a preheating process, (b) is after completion | finish of a constant rate evaporation process, (C) has each shown the state of the electrode slurry after the reduction process. It is the schematic block diagram which extracted one of the drying zones in FIG. It is a schematic perspective view which shows the perforated plate nozzle of the electrode manufacturing apparatus which concerns on this invention. It is a schematic block diagram which shows the infrared heating element of the electrode manufacturing apparatus which concerns on this invention. It is a flowchart of the manufacturing method of the electrode using the manufacturing apparatus which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. The dimensional ratios in the drawings are exaggerated for convenience of explanation, and are different from the actual ratios.

  As shown in FIG. 1, the electrode manufacturing apparatus 1 according to the embodiment of the present invention conveys current collectors 101 and 201, applies electrode slurry 110 and 210 containing an active material to the current collectors 101 and 201, and The formed coating layer is dried in a drying furnace 30 to be described later, and an electrode in which the electrode layer overlaps with the current collectors 101 and 201 is manufactured.

  First, an electrode manufactured by the electrode manufacturing apparatus 1 according to this embodiment will be described.

  The electrode has a positive electrode 100 and a negative electrode 200.

  As shown in FIG. 2A, the positive electrode 100 includes a positive electrode slurry 110 (hereinafter, positive electrode) having a positive electrode current collector 101, a positive electrode active material 111, a binder 112, a conductivity imparting agent 113, and a solvent 114. In some cases, it is referred to as a slurry.) And the solvent 114 in the positive electrode slurry 110 is dried.

  Similarly, as illustrated in FIG. 3A, the negative electrode 200 includes a negative electrode current slurry 201, a negative electrode active material 211, a binder 212, a conductivity-imparting agent 213, and a solvent 214. Hereinafter, the negative electrode slurry may be referred to), and the solvent 214 in the negative electrode slurry 210 is dried to be manufactured.

  For the current collectors 101 and 201, an appropriate material such as aluminum, copper, nickel, iron, stainless steel, or the like can be used. Specifically, for example, a material such as aluminum can be used for the positive electrode current collector 101, and a material such as copper can be used for the negative electrode current collector 201. Although there is no restriction | limiting in particular about the specific thickness of the electrical power collectors 101 and 201, For example, in the case of aluminum, it is a thin film about 20 micrometers, and in the case of copper, it is about 10 micrometers.

  The positive electrode slurry 110 has, for example, a positive electrode active material 111, a binder 112, and a conductivity imparting agent 113, and is set to a predetermined viscosity by adding a solvent 114. The positive electrode active material 111 is, for example, lithium manganate. The binder 112 is, for example, PVDF (polyvinylidene fluoride). The conductivity imparting agent 113 is, for example, acetylene black. The solvent 114 is, for example, NMP (normal methyl pyrrolidone). The positive electrode active material 111 is not particularly limited to lithium manganate, but it is preferable to apply a lithium-transition metal composite oxide from the viewpoint of capacity and output characteristics. As the conductivity imparting agent 113, for example, carbon black or graphite can be used. The binder 112 and the solvent 114 are not limited to PVDF and NMP. Water may be used as the solvent 114.

  The negative electrode slurry 210 includes, for example, a negative electrode active material 211, a binder 212, and a conductivity imparting agent 213, and has a predetermined viscosity by adding a solvent 214. The negative electrode active material 211 is, for example, graphite. The binder 212 is, for example, PVDF (polyvinylidene fluoride). The conductivity imparting agent 213 is, for example, acetylene black. The solvent 214 is, for example, NMP (normal methyl pyrrolidone). Note that the negative electrode active material 211 is not particularly limited to graphite, and it is also possible to use hard carbon or a lithium-transition metal composite oxide. As the conductivity imparting agent 213, for example, carbon black or graphite can be used. The binder 212 and the solvent 214 are not limited to PVDF and NMP. Water may be used as the solvent 214.

  The positive electrode 100 and the negative electrode 200 have the following characteristics.

  As shown in FIGS. 2C and 3C, the electrode slurries 110 and 210 are dried by an electrode manufacturing method to be described later, so that the current collectors 101 and 201 of the electrode layers 103 and 203 overlap. In the region, the component concentrations of the binders 112 and 212 are higher than the region on the surface layer side opposite to the side where the current collectors 101 and 201 overlap.

  Furthermore, when the total thickness of the electrode layers 103 and 203 is 1, the current collector vicinity portion A01, which is a region from the side where the current collectors 101 and 201 of the electrode layers 103 and 203 overlap to 1/4, There is 20-40% of all integrated intensities.

  Here, the definition of the integrated intensity and the measurement method will be described. When the binders 112 and 212 are measured by Raman spectroscopy, a peak appears at a specific wavelength. For example, when the electrode is cut and the cross sections of the electrode layers 103 and 203 are taken out, the Raman is measured in the region of the thickness 120 μm and the width 100 μm from the current collectors 101 and 201 to the surface layers of the electrode layers 103 and 203. The peaks of the binders 112 and 212 appear at each portion in the 120 μm × 100 μm plane, and the intensities of these peaks are integrated to obtain all integrated intensities. Further, the distance from the current collectors 101 and 201 to the surface layers of the electrode layers 103 and 203 is divided into four, and the integration of the peaks in the region from the side where the current collectors 101 and 201 of the electrode layers 103 and 203 overlap to ¼. The intensity is calculated, and this value is divided by all the integrated intensities to calculate the relative intensity.

  Further, the current collector vicinity portion A01 is more electrode layer than the electrode layer surface layer vicinity portion A02 which is a region from the surface layer opposite to the side where the current collectors 101, 201 of the electrode layers 103, 203 overlap to 1/4. The integrated strength of the binders 112 and 212 included in 103 and 203 is high.

  By having the characteristics as described above, since the component concentration of the binders 112 and 212 in the current collector vicinity A01 is increased, the adhesion strength between the current collectors 101 and 201 and the electrode layers 103 and 203 is improved. In addition, a high-performance electrode can be provided.

  The negative electrode 200 further has the following characteristics.

  As shown in FIG.3 (c), by drying the negative electrode slurry 210 with the electrode manufacturing method mentioned later, in the electrode layer surface layer vicinity part A02, the electrode which is an area | region from 1/4 to 1 on the basis of the surface layer side The density | concentration of the electroconductivity imparting agent 213 becomes higher than layer center part A03. This is because, in the negative electrode 200, acetylene black (specific gravity: 1. .gamma.) Added as a conductivity imparting agent 213 as compared with crystalline carbon such as graphite (specific gravity: 2.2) used as the negative electrode active material 211. This is because the amorphous carbon as in 9) has a smaller specific gravity, so that the conductivity-imparting agent 213 easily moves to the surface layer of the electrode layer 203 as the solvent 214 evaporates.

  Further, in the negative electrode 200, the average D / G value, which is the intensity ratio of the peak of the D band to the G band of carbon measured by Raman spectroscopy, is Rs at the electrode layer surface vicinity A02 and Rb at the electrode layer center A03. In this case, the relationship of 2.0 ≧ Rs / Rb is satisfied. This means that when the conductivity imparting agent 213 moves to the surface layer of the electrode layer 203 as described above, an upper limit is set for the amount of movement.

  That is, the average D / G value has a correlation with the degree of graphitization (the degree of crystallinity), and the smaller the D / G value, the higher the degree of graphitization, that is, the higher the crystallinity of carbon. As described above, in the negative electrode 200, the amorphous carbon (low degree of graphitization) applied as the conductivity-imparting agent 213 may move to the surface layer side of the electrode layer 203 in the evaporation step. At this time, by setting 2.0 ≧ Rs / Rb by an electrode manufacturing method to be described later, it is possible to suppress the amorphous carbon from excessively moving to the surface layer side of the electrode layer 203 and to maintain high adhesion strength. it can.

  With the above characteristics, the adhesion strength between the current collector 201 and the electrode layer 203 is improved, and the high-performance negative electrode 200 can be provided.

  Next, the electrode manufacturing apparatus 1 according to this embodiment will be described. Here, the positive electrode 100 will be described as an example.

  As shown in FIG. 1, the electrode manufacturing apparatus 1 includes a transport unit 10 that transports the current collector 101, a coating unit 20 that applies the electrode slurry 110 to the current collector 101, and a drying furnace 30 that dries the electrode slurry 110. And have. Details will be described below.

  The transport unit 10 includes a supply roll 11 that supplies the current collector 101 before the electrode slurry 110 is applied, a winding roll 12 that winds the current collector 101 after the electrode slurry 110 is dried, and a winding roll. And a motor M that rotates the motor 12. The transport unit 10 further includes a plurality of support rolls 13 that are disposed between the supply roll 11 and the take-up roll 12 and hold the lower surface of the current collector 101. A strip-shaped current collector 101 is wound around the supply roll 11 in advance. When the motor M is driven to rotate the winding roll 12, the current collector 101 is supplied from the supply roll 11, conveyed in the drying furnace 30, and taken up by the winding roll 12. Thus, the conveyance part 10 conveys the elongate collector 101 continuously.

  Application | coating of the electrode slurry 110 to the electrical power collector 101 is performed by the application part 20, conveying the electrical power collector 101. FIG. The application unit 20 includes a coater 21 that applies the electrode slurry 110 to the current collector 101. The coater 21 is disposed facing the current collector 101 and intermittently applies the electrode slurry 110 to the current collector 101 being conveyed.

  As shown in FIG. 4, the drying furnace 30 includes a casing 31 that forms a conveying path for the current collector 101, a hot air generating unit 32 that generates hot air, and a hot air from the hot air generating unit 32 that is applied to the electrode slurry 110. The upper nozzle 33 that blows out to the upper part of 102 and the lower nozzle 34 that blows hot air from the hot air generating part 32 to the lower part of the coating layer 102 of the electrode slurry 110 are provided. In FIG. 4, a first drying zone 36 described later is shown. The inside of the drying furnace 30 is formed from drying zones 36 to 41 partitioned into a plurality (six in FIG. 1) by providing partition walls 35 in the casing 31. For convenience of explanation, the first drying zone 36, the second drying zone 37, and the third drying zone 36 to 41 are sequentially arranged from the upstream side in the direction in which the current collector 101 is conveyed (in order from the left side in FIG. 1). Are defined as a drying zone 38, a fourth drying zone 39, a fifth drying zone 40, and a sixth drying zone 41.

  In the first drying zone 36 and the second drying zone 37, a preheating step S04 for preheating the electrode slurry 110 is performed.

  In the third drying zone 38 and the fourth drying zone 39, a constant rate evaporation step S05 in which the drying rate of the electrode slurry 110 is constant is performed.

  In the fifth drying zone 40 and the sixth drying zone 41, a rate-decreasing evaporation step S06 in which the drying rate of the electrode slurry 110 gradually decreases depending on the decrease in the solvent content of the electrode slurry 110 is performed.

  As shown in FIG. 4, the hot air generator 32 includes a first pipe 44 that connects the air supply fan 42 and the circulation fan 43, a second pipe 45 that connects the circulation fan 43 and the upper nozzle 33, and the circulation fan 43. And a third pipe 46 connecting the lower nozzle 34. The hot air generator 32 further includes a fourth pipe 49 that connects the exhaust port 47 and the exhaust fan 48 in the drying furnace 30, and a fifth pipe 51 that connects the circulation port 50 and the circulation fan 43 in the drying furnace 30. Have. A heater 52 for adjusting the temperature of hot air to be supplied is provided between the supply fan 42 and the circulation fan 43. Each of the pipes 44 to 46, 49, 51 is provided with a damper 53 for adjusting the amount of hot air. The temperature of the hot air is not particularly limited because it differs depending on the environmental temperature, the type of the electrode slurry 110, and the like, but is 100 ± 40 ° C., for example.

  The hot air supplied from the air supply fan 42 passes through the first pipe 44 and reaches the circulation fan 43. At this time, the amount of hot air is adjusted by the damper 53, and the temperature of the hot air is adjusted by the heater 52. The hot air that has exited the circulation fan 43 is distributed to the second pipe 45 and the third pipe 46. The hot air distributed to the second pipe 45 is adjusted in air volume by the damper 53 and reaches the upper nozzle 33. On the other hand, the amount of the hot air distributed to the third pipe 46 is adjusted by the damper 53 and reaches the lower nozzle 34. Hot air that has reached the upper and lower nozzles 33 and 34 is blown out to the electrode slurry 110 from the upper and lower nozzles 33 and 34, respectively. As shown in FIG. 5, the upper nozzle 33 is a perforated plate nozzle having holes 54, and has an aperture ratio of 10% or more. The hot air blown out from the upper and lower nozzles 33 and 34 is divided into hot air that is discarded as exhaust and hot air that circulates through the hot air generator 32 for reuse. The hot air thrown away as exhaust passes through the fourth pipe 49 from the exhaust port 47 provided in the drying furnace 30, reaches the exhaust fan 48, and is exhausted by the exhaust fan 48. At this time, the air volume is adjusted by the damper 53. The hot air that is circulated again passes through the fifth pipe 51 from the circulation port 50 provided in the drying furnace 30 and reaches the circulation fan 43. At this time, the air volume is adjusted by the damper 53 and the temperature is adjusted again by the heater 52. As shown in FIGS. 4 and 6, the hot air generator 32 has an infrared heating element 55 between the upper nozzles 33, and the infrared heating element 55 is heated by the power source P and is used for explosion protection. Cooling air C cools the surroundings.

  Furthermore, the electrode manufacturing apparatus 1 includes a controller 56 that controls the operation of the coating unit 20. The controller 56 is mainly composed of a CPU and a memory, and a program for controlling the operation is stored in the memory. The controller 56 controls the operation of the application unit 20 to adjust the application amount and application thickness of the electrode slurry 110, and also controls the operation of the hot air generation unit 32 to adjust the temperature of the supply air, the air volume, etc. adjust. The controller 56 also controls the operation of the motor M to adjust the conveyance speed of the current collector 101.

  Before describing the electrode manufacturing method using the electrode manufacturing apparatus 1 according to the present embodiment, the phenomenon that occurs when the temperature and air volume of the supply air supplied to the drying furnace 30 are changed greatly will be described. Here, the positive electrode 100 will be described as an example.

  In the drying furnace 30 using hot air, the drying speed can be improved by increasing the hot air temperature and increasing the air volume and increasing the removal amount of the solvent 114 in the surface portion of the coating layer 102. However, according to such a drying method, drying is accelerated, and the binder 112 is segregated near the surface of the electrode layer 103. For this reason, it is difficult to obtain a coating film that is in close contact with the current collector 101, that is, a strongly adherent electrode layer 103.

  As a cause of segregation of the binder 112 when the hot air temperature is increased, the following can be cited. Since the coating layer 102 contains the binder 112 dissolved in the solvent 114 at the time of drying, the solvent 114 itself convects in the coating layer 102 when the coating layer 102 is exposed to a high temperature environment. Wake up. As a result, the dissolved binder 112 is segregated.

  Moreover, the following can be mentioned as a cause of the segregation of the binder 112 when the air volume is increased. Only the solvent 114 in the vicinity of the surface of the coating layer 102 is preferentially volatilized and only the vicinity of the surface is dried first, and the solvent 114 is directed from the deep part to the surface by a capillary phenomenon due to cracks or holes generated in the surface dry part. And suck it up. As a result, the dissolved binder 112 is segregated.

  Under drying conditions that can cause segregation of the binder 112 during drying, the surface roughness of the electrode layer 103 is large and the adhesion is weak, so that the contact amount or the contact area between the current collector 101 and the electrode layer 103 is reduced. For this reason, not only the resistance value in the battery in the initial stage of use but also the resistance value in the battery after repeated charge / discharge increases, leading to a decrease in electrode performance.

  In order to eliminate the segregation of the generated binding material 112, there is a method in which the dried electrode 100 is compressed by a roll press or the like. However, since the structure is forcibly changed after the drying is completed and the electrode layer 103 is fixed, the adhesion strength of the electrode layer 103 is not improved so much. Moreover, it is desirable to avoid adding a compression step after the drying step from the viewpoint of realizing mass production at a low cost.

  Next, an electrode manufacturing method using the electrode manufacturing apparatus 1 according to the present embodiment will be described based on the flowchart of FIG. Here, the positive electrode 100 will be described as an example.

  The current collector transport step S01 is a step of transporting the current collector 101. In the current collector transport step S01, the motor M is driven to rotate the take-up roll 12, and the current collector 101 is unwound from the supply roll 11 and wound around the take-up roll 12. The controller 56 controls the operation of the motor M and adjusts the conveyance speed.

  The coating step S02 is a step of coating the current collector 101 with the electrode slurry 110 including the active material 111, the binder 112, the conductivity imparting agent 113, and the solvent 114. The coater 21 disposed so as to face the current collector 101 intermittently applies the electrode slurry 110 to the surface of the moving current collector 101. The controller 56 controls the operation of the application unit 20 and adjusts the application amount and application thickness of the electrode slurry 110.

  The hot air generation step S03 is a step of generating hot air for drying the electrode slurry 110. In the hot air generation step S03, the temperature of the hot air supplied from the air supply fan 42 is adjusted by the heater 52 and reaches the circulation fan 43. The hot air exiting the circulation fan 43 is separated and reaches the upper and lower nozzles 33 and 34.

  In the preheating step S04, hot air is blown from the upper and lower nozzles 33, 34 to the electrode slurry 110 so as to give heat until the evaporation of the slurry before being brought into the drying step is started, or to the electrode slurry 110 by the infrared heating element 55. Give heat. The specific amount of heat supplied is calculated by a procedure in which a hot air having a specific temperature and air volume is actually applied to confirm the evaporation amount several times, and the appropriate temperature and air volume are quantified. The controller 56 controls the heater 52, the various fans 42, 43, 48, and the like, and adjusts the temperature and volume of hot air. The preheating step S04 is performed in the first drying zone 36 and the second drying zone 37. When this step is completed, the amount of the solvent remaining in the electrode slurry 110 is 100 to 90% by weight.

  In the constant rate evaporation step S05, hot air is passed through the upper and lower nozzles 33 and 34 so as to evaporate and remove the solvent 114 while suppressing the movement of the components of the binder 112 and the conductivity-imparting agent 113 due to the evaporation of the solvent 114. The slurry 110 is blown out, or the electrode slurry 110 is heated by the infrared heating element 55. The constant rate evaporation step S05 is performed in the third drying zone 38 and the fourth drying zone 39. When this step is completed, the amount of the solvent remaining in the electrode slurry 110 is 95 to 1% by weight.

  In the reduction evaporation step S06, the electrode slurry 110 is concentrated, and the components of the binder 112 and the conductivity-imparting agent 113 are less likely to move. For this reason, hot air is blown from the upper and lower nozzles 33, 34 to the electrode slurry 110 or heat is applied to the electrode slurry 110 by the infrared heating element 55 so as to rapidly evaporate and remove the remaining solvent 114. The decreasing rate evaporation step S06 is performed in the fifth drying zone 40 and the sixth drying zone 41. When this step is completed, the amount of the solvent remaining in the electrode slurry 110 is 0.1% by weight or less.

  In the above steps S04 to S06 (hereinafter, steps S04 to S06 may be referred to as a drying step), the electrode slurry 110 is dried under conditions that do not cause segregation of the binder 112. Therefore, the adhesion between the current collector 101 and the electrode layer 103 is improved, and the resistance value in the battery after repeated charging and discharging is lowered as well as the resistance value in the battery in the initial stage of use. It is possible to improve. Furthermore, since an appropriate temperature condition can be set in the drying process, the drying time is shortened as a whole.

  Step S07 is a process of exhausting and circulating hot air. The hot air blown out to the electrode slurry 110 is divided into hot air discarded as exhaust and hot air circulating through the hot air generation unit 32 for reuse. Hot air thrown away as exhaust is exhausted by an exhaust fan 48 from an exhaust port 47 provided in the drying furnace 30. Further, the temperature of the hot air for reuse is adjusted by the heater 52, reaches the circulation fan 43 again, and is reused.

  As described above, the electrode according to the present embodiment is an electrode in which the electrode layers 103 and 203 overlap the current collectors 101 and 201, and the region on the side where the current collectors 101 and 201 overlap the electrode layers 103 and 203. Is an electrode in which the component concentrations of the binders 112 and 212 included in the electrode layers 103 and 203 are higher than the region on the surface layer side opposite to the side where the current collectors 101 and 201 overlap. For this reason, the adhesion strength between the current collectors 101 and 201 and the electrode layers 103 and 203 is increased. Therefore, not only the resistance value in the battery in the initial stage of use but also the resistance value in the battery after repeated charge / discharge is lowered, and the battery performance is improved. In addition, even if the electrolyte solution soaks and the electrode layers 103 and 203 and the binders 112 and 212 swell, the adhesion strength between the current collectors 101 and 201 and the electrode layers 103 and 203 is high. Since 203 does not peel from the current collectors 101 and 201, the direct current resistance value of the electrode does not increase, and the battery performance can be maintained.

  When the total thickness of the electrode layers 103 and 203 is 1, 20 to 40% of the integrated strength of all the binders 112 and 212 exists in the current collector vicinity A01. For this reason, the adhesion strength between the current collectors 101 and 201 and the electrode layers 103 and 203 can be reliably increased.

  Further, the current collector vicinity portion A01 is more bound than the electrode layer surface vicinity portion A02, which is a region from the surface layer side opposite to the side where the current collectors 101 and 201 of the electrode layers 103 and 203 overlap to 1/4. The integrated strength of the materials 112 and 212 is high. For this reason, the adhesion strength between the current collectors 101 and 201 and the electrode layers 103 and 203 can be reliably increased.

  Further, in the electrode layer surface layer vicinity portion A02, there is a region where the concentration of the conductivity imparting agents 113 and 213 is higher than that of the electrode layer center portion A03 that is a region from 1/4 to 1 with respect to the surface layer side. For this reason, the component concentration of the binders 112 and 212 in the current collector vicinity A01 is relatively high, and the adhesion strength between the current collectors 101 and 201 and the electrode layers 103 and 203 is high.

  Also, when the average D / G value, which is the intensity ratio of the peak of the D band to the G band of carbon measured by Raman spectroscopy, is Rs at the electrode layer surface vicinity A02 and Rb at the electrode layer center A03 In addition, the relationship of 2.0 ≧ Rs / Rb is satisfied. For this reason, the electroconductivity imparting agents 113 and 213 are not excessively increased on the surface side of the electrode layer, and the adhesion strength between the current collectors 101 and 201 and the electrode layers 103 and 203 is increased.

  As described above, the electrode manufacturing apparatus 1 according to this embodiment includes the electrode slurry 110 including the active materials 111 and 211, the binders 112 and 212, the conductivity imparting agents 113 and 213, and the solvents 114 and 214, The coating layers 102 and 202 formed by applying 210 to the current collectors 101 and 201 are dried in the drying furnace 30 to manufacture electrodes in which the electrode layers 103 and 203 overlap the current collectors 101 and 201. It is the electrode manufacturing apparatus 1 to do. The electrode manufacturing apparatus 1 includes a perforated plate nozzle (upper nozzle) 33 having a large number of holes 54 at the outlet of hot air for heating and drying the surfaces of the electrode slurries 110 and 210 on which the coating layers 102 and 202 are formed by hot air. And the aperture ratio of the perforated plate nozzle 33 is 10% or more. Therefore, the electrode slurries 110 and 210 can be appropriately dried in the drying step, and the component concentrations of the binders 112 and 212 in the current collector vicinity A01 are increased, so that the current collectors 101 and 201 and the electrode The adhesion strength with the layers 103 and 203 is increased.

  Moreover, it has the infrared rays heat generating body 55 for heat-drying the surface in which the application layers 102 and 202 of the electrode slurry 110 and 210 were formed. For this reason, the electrode slurries 110 and 210 can be appropriately dried in the drying step, and the concentration of the components of the binders 112 and 212 in the current collector vicinity portion A01 is increased, whereby the current collectors 101 and 201 and The adhesion strength with the electrode layers 103 and 203 is increased.

  Further, as described above, the electrode manufacturing method according to the present embodiment is an electrode manufacturing method for manufacturing an electrode in which the electrode layers 103 and 203 overlap the current collectors 101 and 201, and preheats the electrode slurries 110 and 210. The preheating step S04, the constant rate evaporation step S05 in which the drying rate of the electrode slurries 110 and 210 is constant, and the drying rate of the electrode slurries 110 and 210 gradually depends on the decrease in the solvent content of the electrode slurries 110 and 210. A decreasing rate evaporation step S06. For this reason, since an appropriate temperature condition can be set in each process, the drying time as a whole can be shortened, and further, the equipment can be reduced.

  In addition, in the preheating step S04, the constant rate evaporation step S05, and the decrease rate evaporation step S06, the amounts of the solvent remaining in the electrode slurries 110 and 210 when the respective steps are finished are 100 to 90% by weight and 95 to 1% by weight, respectively. 5 to 0.01% by weight. For this reason, the solvents 114 and 214 are appropriately dried, and a large amount of the binders 112 and 212 can be present in the vicinity of the current collector, so that the current collector 101 and 201 and the electrode layers 103 and 203 are in close contact with each other. Strength increases.

  The constant rate evaporation step S05 includes a first constant rate evaporation step and a second constant rate evaporation step, and the amount of the solvent remaining in the electrode slurries 110 and 210 when each step is finished is 95 to 65% by weight, It is in the range of 65 to 1% by weight. For this reason, the solvents 114 and 214 are appropriately dried, and a large amount of the binders 112 and 212 can be present in the vicinity of the current collector A01, and the current collectors 101 and 201 and the electrode layers 103 and 203 The adhesion strength of is increased.

  The amount of the solvent remaining in the electrode slurries 110 and 210 after the reduction evaporation step S06 is 0.1% by weight or less. For this reason, since the solvents 114 and 214 hardly remain after the drying process is completed, the adhesion strength between the current collectors 101 and 201 and the electrode layers 103 and 203 is increased.

(Modification example)
The preheating step S04, the constant rate evaporation step S05, and the decremental rate evaporation step S06, which are drying steps in the drying furnace 30, have been shown to be implemented in two drying zones, but the present invention is not limited to this mode. The number of zones can be increased or decreased.

  In the present embodiment, the hot air generating unit 32 includes the hot air blown from the upper and lower nozzles 33 and 34 and the infrared heating element 55, but either one of them may be present alone, Other heat generation methods may be used.

  Moreover, in this embodiment, although the aperture ratio of the upper nozzle 33 from which the hot air for drying the electrode slurries 110 and 210 is blown is 10% or more, it is not limited to this.

  In the present embodiment, the fifth pipe 51 for reusing the hot air blown from the upper and lower nozzles 33 and 34 is provided, but it may be omitted.

  Moreover, although the form which conveys the electrical power collectors 101 and 201 continuously was illustrated in this embodiment, the form conveyed in a batch type may be sufficient.

  Furthermore, the present invention is not limited to the case where the electrode slurries 110 and 210 are intermittently applied, and it goes without saying that the present invention can also be applied to the case where the electrode slurries 110 and 210 are continuously applied.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Examples 1 to 8, 17, and 18 and Comparative Example 1 correspond to the positive electrode, and Examples 9 to 16 and Comparative Example 2 correspond to the negative electrode.

[Example 1]
(Composition of positive electrode slurry)

(Production of positive electrode slurry)
A positive electrode slurry having the composition shown in Table 1 was prepared as follows. First, 4.4 parts by weight of PVDF was dissolved in 30 parts by weight of NMP to prepare a PVDF solution. Next, 34.4 parts by weight of the PVDF solution is added to the mixed powder of 4.4 parts by weight of the conductivity-imparting agent and 100 parts by weight of the lithium manganate powder, and the planetary mixer (PVM100 manufactured by Asada Tekko Co., Ltd.) is used. After kneading, 37 parts by weight of NMP was added to the kneaded product to obtain a positive electrode slurry (solid content concentration: 62% by weight).

(Application and drying of positive electrode slurry)
The positive electrode slurry was applied to one side of the current collector by a coater while running a 20 μm thick aluminum foil current collector at a running speed of 8 m / min.

  Subsequently, a drying furnace (one block is 2.5 m, 8 continuous furnaces) in which the drying zone in the constant rate evaporation step is increased by two zones with respect to FIG. 1 and FIG. 4 (distance from the upper nozzle to the foil (D1) : 10 to 150 mm, the distance from the slit-type lower nozzle to the foil (D2): 10 to 75 mm), the positive electrode slurry was dried by the following drying process.

First, the furnace temperature in each zone of the preheating process (first drying zone and second drying zone) 135 ° C., upper nozzle (opening ratio 10%, D1: 50 mm) and lower nozzle (slit width: 5 mm, D2: 10 mm) the heating was carried out under the conditions of the total blowoff air volume 50 Nm ³ / min of (air volume ^{7 Nm} 3 / min to introduce the circulating air volume 43 nm ³ / min and the outside).

Subsequently, the furnace temperature in each zone of the constant rate evaporation step (the third drying zone to the sixth drying zone) is 130 ° C., the upper nozzle (opening ratio 30%, D1: 50 mm) and the lower nozzle (slit width: 5 mm, D2: The constant rate evaporation was performed under the conditions of a total blown air volume of 10 Nm) of 100 Nm ³ / m (circulating air volume of 10 Nm ³ / min and an air volume of 90 Nm ³ / min introduced from the outside).

Furthermore, the furnace temperature in each zone of the reduction rate evaporation process (seventh drying zone and eighth drying zone) is 140 ° C., the upper nozzle (opening ratio 10%, D1: 50 mm) and the lower nozzle (slit width: 5 mm, D2: The reduced evaporation was performed under the conditions of a total blowing air volume of 70 Nm ³ / min (10 mm) (circulating air volume 67 Nm ³ / min and air volume ³ Nm ³ / min introduced from the outside).

  The NMP concentration sensor installed at the top of each process measures the amount of NMP that evaporates in each process, and NMP remaining in the coating layer (the positive electrode slurry coated on the current collector) that passes through each process The content was calculated.

  As a result, the NMP amount brought into the drying furnace (residual NMP amount is 100% by weight), the evaporated NMP amount in the preheating step is 7% by weight (residual NMP amount is 93% by weight), and the evaporated NMP in the constant rate evaporation step The amount was 88% by weight (the amount of residual NMP was 5% by weight), and the amount of evaporated NMP in the decremental evaporation step was 4.97% by weight (the amount of residual NMP was 0.03% by weight).

  Further, when the NMP content remaining in the positive electrode layer when the reduction evaporation process was completed was analyzed by gas chromatography, it was confirmed to be 0.03% by weight.

  Furthermore, application | coating and drying were carried out on the back surface of the aluminum foil under the same conditions as described above to form a sheet-like electrode having electrode active material layers on both surfaces. The sheet-like electrode was compression-molded by applying a roller press and cut to prepare a positive electrode having a thickness of about 100 μm on one side of the active material layer. When the surface of the positive electrode was observed, no cracks were observed.

  Further, the adhesion strength of the electrode active material layer after pressing was 90 ° tensile test (testing machine: manufactured by Imada Manufacturing Co., Ltd., model number: SV-52NA-20M, load cell maximum load: 200 N, tensile speed: 100 mm / min, sample (Strip: 15 mm × 80 mm).

[Example 2]
(Composition of positive electrode slurry)

(Production of positive electrode slurry)
A positive electrode slurry having the composition of Table 2 was prepared according to Example 1.

(Application and drying of positive electrode slurry)
In accordance with Example 1, the positive electrode slurry was applied to one side of a 20 μm aluminum foil current collector using a coater.

  Subsequently, the positive electrode slurry was dried by the following drying process.

First, the furnace temperature in the preheating process (first drying zone) 135 ° C., the total blown air flow rate of 25 Nm ³ / min from the upper nozzle (opening ratio 10%, D1: 25 mm) and the lower nozzle (slit width: 5 mm, D2: 10 mm) (Circulation air volume 25 Nm ³ / min), furnace temperature 135 ° C. of preheating process (second drying zone), upper nozzle (opening ratio 10%, D1: 50 mm) and lower nozzle (slit width: 5 mm, D2: 10 mm) The temperature was increased under conditions of a total blown air volume of 25 Nm ³ / min (circulating air volume of 20 Nm ³ / min and an air volume of 5 Nm ³ / min introduced from the outside).

Subsequently, the furnace temperature in each zone of the constant rate evaporation step (third drying zone to sixth drying zone) 125 ° C., the upper nozzle (opening ratio 30%, D1: 50 mm) and the lower nozzle (slit width: 5 mm, D2: The constant rate evaporation was performed under conditions of a total blown air volume of 10 Nm) of 100 Nm ³ / m (circulating air volume of 8 Nm ³ / min and an air volume of 92 Nm ³ / min introduced from the outside).

Furthermore, the furnace temperature in each zone of the reduction rate evaporation process (seventh drying zone and eighth drying zone) is 140 ° C., the upper nozzle (opening ratio 10%, D1: 25 mm) and the lower nozzle (slit width: 5 mm, D2: The reduced evaporation was performed under the conditions of a total blowing air volume of 70 Nm ³ / min (10 mm) (circulating air volume 67 Nm ³ / min and air volume ³ Nm ³ / min introduced from the outside).

  As a result, with respect to the amount of NMP brought into the drying furnace (the amount of residual NMP is 100% by weight), the amount of evaporated NMP in the preheating step is 5% by weight (the amount of residual NMP is 95% by weight), and the amount of evaporated NMP in the constant rate evaporation step The amount was 92% by weight (the amount of residual NMP was 3% by weight), and the amount of evaporated NMP in the decremental evaporation step was 2.97% by weight (the amount of residual NMP was 0.03% by weight).

  Further, when the NMP content remaining in the positive electrode layer when the reduction evaporation process was completed was analyzed by gas chromatography, it was confirmed to be 0.03% by weight.

  Further, according to Example 1, the surface of the positive electrode was observed, and the adhesion strength of the electrode active material layer after pressing was measured.

[Example 3]
According to Example 1, the positive electrode slurry was applied to one side of the current collector by a coater while running a 20 μm thick aluminum foil current collector at a running speed of 12 m / min.

  Subsequently, the positive electrode slurry was dried by the following drying process.

First, the furnace temperature in the preheating step (first drying zone) is 135 ° C., and the total blown air volume of the upper nozzle (opening ratio: 10%, D1: 25 mm) and the lower nozzle (slit width: 5 mm, D2: 10 mm) is 30 Nm ³ / min. (Circulation air volume 30 Nm ³ / min), furnace temperature in the preheating step (second drying zone) 135 ° C., upper nozzle (opening ratio 10%, D1: 25 mm) and lower nozzle (slit width: 5 mm, D2: 10 mm) The temperature was increased under conditions of a total blown air volume of 40 Nm ³ / min (circulating air volume of 25 Nm ³ / min and an air volume of 15 Nm ³ / min introduced from the outside).

Subsequently, the furnace temperature in each zone of the constant rate evaporation step (third drying zone to sixth drying zone), 130 ° C., upper nozzle (opening ratio 30%, D1: 15 mm) and lower nozzle (slit width: 5 mm, D2: were fixed-rate evaporation under conditions of total blowoff air volume 150 Nm ³ / m (air volume 130 Nm ³ / min to introduce the circulating air volume 20 Nm ³ / min and external) of 10 mm).

Furthermore, the furnace temperature in each zone of the reduction rate evaporation process (seventh drying zone and eighth drying zone) is 140 ° C., the upper nozzle (opening ratio 10%, D1: 15 mm) and the lower nozzle (slit width: 5 mm, D2: was falling-rate evaporation under conditions of total blowoff air volume 80 Nm ³ / min (air volume 10 Nm ³ / min to introduce the circulating air volume 70 Nm ³ / min and external) of 10 mm).

  As a result, with respect to the amount of NMP brought into the drying furnace (residual NMP amount is 100% by weight), the evaporated NMP amount in the preheating step is 4% by weight (residual NMP amount is 96% by weight), and the evaporated NMP in the constant rate evaporation step The amount was 93% by weight (the amount of residual NMP was 3% by weight), and the amount of evaporated NMP in the decreasing evaporation step was 2.97% by weight (the amount of residual NMP was 0.03% by weight).

  Further, when the NMP content remaining in the positive electrode layer when the reduction evaporation process was completed was analyzed by gas chromatography, it was confirmed to be 0.03% by weight.

  Further, according to Example 1, the surface of the positive electrode was observed, and the adhesion strength of the electrode active material layer after pressing was measured.

[Example 4]
In accordance with Example 1, the positive electrode slurry was applied to one side of the current collector by a coater while running a 20 μm thick aluminum foil current collector at a running speed of 16 m / min.

  Subsequently, the positive electrode slurry was dried by the following drying process.

First, the furnace temperature in the preheating step (first drying zone) 140 ° C., the total blown air volume 40 Nm ³ / min of the upper nozzle (opening ratio 10%, D1: 15 mm) and the lower nozzle (slit width: 5 mm, D2: 10 mm) (Circulation air volume 40Nm ³ / min), furnace temperature in preheating process (second drying zone) 135 ° C., upper nozzle (opening ratio 10%, D1: 15 mm) and lower nozzle (slit width: 5 mm, D2: 10 mm) the heating was carried out under the conditions of the total blowoff air volume 50 Nm ³ / min (air volume 30 Nm ³ / min to introduce the circulating air volume 20 Nm ³ / min and the outside).

Subsequently, the furnace temperature in each zone of the constant rate evaporation step (third drying zone to sixth drying zone) 135 ° C., upper nozzle (opening ratio 30%, D1: 15 mm) and lower nozzle (slit width: 5 mm, D2: were fixed-rate evaporation under conditions of total blowoff air volume 200 Nm ³ / min (air volume 175 nm ³ / min to introduce the circulating air volume 25 Nm ³ / min and external) of 10 mm).

Furthermore, the furnace temperature in each zone of the reduction rate evaporation process (seventh drying zone and eighth drying zone) is 140 ° C., the upper nozzle (opening ratio 10%, D1: 15 mm) and the lower nozzle (slit width: 5 mm, D2: (10 mm) The total blown air volume was 120 Nm ³ / min (circulation air volume 105 Nm ³ / min and the amount of air introduced from the outside was 15 Nm ³ / min).

  As a result, with respect to the amount of NMP brought into the drying furnace (residual NMP amount is 100% by weight), the evaporated NMP amount in the preheating step is 3% by weight (residual NMP amount is 97% by weight), and the evaporated NMP in the constant rate evaporation step The amount was 94% by weight (the amount of residual NMP was 3% by weight), and the amount of evaporated NMP in the decremental evaporation step was 2.97% by weight (the amount of residual NMP was 0.03% by weight).

  Further, when the NMP content remaining in the positive electrode layer when the reduction evaporation process was completed was analyzed by gas chromatography, it was confirmed to be 0.03% by weight.

  Further, according to Example 1, the surface of the positive electrode was observed, and the adhesion strength of the electrode active material layer after pressing was measured.

[Example 5]
In Example 4, an infrared heating furnace was incorporated in the preheating process, the furnace temperature in the preheating process (first drying zone) was 140 ° C., the upper nozzle (opening ratio 20%, D1: 50 mm), and the lower nozzle (slit width: 5 mm). , D2: 10 mm), total blown air volume 25 Nm ³ / min (circulating air volume 25 Nm ³ / min), furnace temperature in the preheating step (second drying zone) 135 ° C., upper nozzle (opening ratio 20%, D1: 50 mm) and lower nozzle (slit width: 5mm, D2: 10mm) and heating was carried out under the conditions of the total blowoff air volume 50 Nm ³ / min (air volume 40 Nm ³ / min to introduce the circulating air volume 10 Nm ³ / min and external) of the. Except this, it was the same as Example 4.

[Example 6]
In Example 4, an infrared heating furnace apparatus was incorporated in the constant rate evaporation step, the furnace temperature in each zone of the constant rate evaporation step (third drying zone to sixth drying zone), an upper nozzle (opening ratio 35%, D1: 50mm) and the lower nozzle (slit width: 5mm, D2: 10mm) with a total blown air volume of 175Nm ³ / m (circulating air volume 0Nm ³ / min and externally introduced air volume 175Nm ³ / min). . Except this, it was the same as Example 4.

[Example 7]
In Example 4, an infrared heating furnace apparatus was incorporated in the reduction heating zone, the furnace temperature in each zone of the reduction evaporation process (seventh drying zone and eighth drying zone), 140 ° C., upper nozzle (opening ratio 20%, D1: 50 mm) and the lower nozzle (slit width: 5 mm, D2: 10 mm) with a total blowing air volume of 70 Nm ³ / min (circulation air volume 55 Nm ³ / min and externally introduced air volume 15 Nm ³ / min). Went. Except this, it was the same as Example 4.

[Example 8]
In Example 4, an infrared heating furnace apparatus was placed at a location 2.5 m from the position where the reduced heating zone was exited, and additional drying was performed at 130 ° C. Except this, it was the same as Example 4.

[Example 9]
(Composition of negative electrode slurry)

(Manufacture of negative electrode slurry)
A negative electrode slurry having the structure of Table 3 was prepared as follows. First, 6.5 parts by weight of PVDF was dissolved in 45 parts by weight of NMP to prepare a PVDF solution. Next, 51.5 parts by weight of the PVDF solution is added to a mixed powder of 1.1 parts by weight of a conductivity imparting agent and 100 parts by weight of natural graphite powder, and kneaded by a planetary mixer (PVM100, manufactured by Asada Tekko) Thereafter, 44 parts by weight of NMP was added to the kneaded material to obtain a negative electrode slurry (solid content concentration 52% by weight).

(Application and drying of negative electrode slurry)
The negative electrode slurry was applied to one side of the current collector by a coater while running a rolled copper foil current collector having a thickness of 10 μm at a running speed of 8 m / min.

  Subsequently, the negative electrode slurry was dried by the following drying process.

First, the furnace temperature in each zone of the preheating process (first drying zone and second drying zone) 125 ° C., upper nozzle (opening ratio 10%, D1: 50 mm) and lower nozzle (slit width: 5 mm, D2: 10 mm) the heating was carried out under the conditions of the total blowoff air volume 30 Nm ³ / min of (air volume 10 Nm ³ / min to introduce the circulating air volume 20 Nm ³ / min and the outside).

Subsequently, the furnace temperature in each zone of the constant rate evaporation step (the third drying zone to the sixth drying zone) is 115 ° C., the upper nozzle (opening ratio is 30%, D1: 50 mm), and the lower nozzle (slit width: 5 mm, D2: The constant rate evaporation was performed under the conditions of a total blown air volume of 60 Nm ³ / m (circulated air volume of 12 Nm ³ / min and an air volume of 48 Nm ³ / min introduced from the outside) of 10 mm).

Furthermore, the furnace temperature in each zone of the reduction rate evaporation process (seventh drying zone and eighth drying zone), 130 ° C., upper nozzle (opening ratio 10%, D1: 50 mm) and lower nozzle (slit width: 5 mm, D2: was falling-rate evaporation under conditions of total blowoff air volume 70 Nm ³ / min (air volume 10 Nm ³ / min to introduce the circulating air volume 60 Nm ³ / min and external) of 10 mm).

  The NMP concentration sensor installed at the top of each process measures the amount of NMP that evaporates in each process, and the NMP remaining in the coating layer (negative electrode slurry coated on the current collector) that passes through each process The content was calculated.

  As a result, with respect to the amount of NMP brought into the drying furnace (residual NMP amount is 100% by weight), the evaporated NMP amount in the preheating step is 4% by weight (residual NMP amount is 96% by weight), and the evaporated NMP in the constant rate evaporation step The amount was 95% by weight (the amount of residual NMP was 1% by weight), and the amount of evaporated NMP in the reduced evaporation step was 0.98% by weight (the amount of residual NMP was 0.02% by weight).

  Further, when the NMP content remaining in the negative electrode layer when the decreasing evaporation process was completed was analyzed by gas chromatography, it was confirmed to be 0.02% by weight.

  Furthermore, it apply | coated and dried on the back surface of the rolled copper foil collector on the same conditions as the above, and formed the sheet-like electrode which has an electrode active material layer on both surfaces. The sheet electrode was compression-molded by roller pressing and cut to prepare a negative electrode having a thickness of about 60 μm on one side of the active material layer. When the surface of the negative electrode was observed, no cracks were observed.

  Further, the adhesion strength of the electrode active material layer after the press was 90 ° tensile test (tester: Imada Seisakusho, model number: SV-52NA-20M, load cell maximum load: 200 N, tensile speed: 100 mm / min, sample piece: 15 mm × 80 mm).

[Example 10]
In accordance with Example 9, the paint was applied to one side of a 10 μm rolled copper foil current collector.

  Subsequently, the negative electrode slurry was dried by the following drying process.

First, the furnace temperature in the preheating step (first drying zone) 125 ° C., the total blown air flow 15 Nm ³ / min of the upper nozzle (opening ratio 10%, D1: 25 mm) and the lower nozzle (slit width: 5 mm, D2: 10 mm) (Circulation air volume 15 Nm ³ / min), furnace temperature in preheating step (second drying zone) 115 ° C., upper nozzle (opening ratio 10%, D1: 50 mm) and lower nozzle (slit width: 5 mm, D2: 10 mm) the heating was carried out under the conditions of the total blowoff air volume 15 Nm ³ / min (air volume 10 Nm ³ / min to introduce the circulating air volume ^{5 Nm} 3 / min and the outside).

Subsequently, the furnace temperature in each zone of the constant rate evaporation step (the third drying zone to the sixth drying zone) is 115 ° C., the upper nozzle (opening ratio is 30%, D1: 25 mm), and the lower nozzle (slit width: 5 mm, D2: The constant rate evaporation was performed under the conditions of a total blown air volume of 60 Nm ³ / m (circulated air volume of 12 Nm ³ / min and an air volume of 48 Nm ³ / min introduced from the outside) of 10 mm).

Furthermore, the furnace temperature in each zone of the reduction rate evaporation process (seventh drying zone and eighth drying zone) is 130 ° C., the upper nozzle (opening ratio 10%, D1: 25 mm) and the lower nozzle (slit width: 5 mm, D2: was falling-rate evaporation under conditions of total blowoff air volume 70 Nm ³ / min (air volume 10 Nm ³ / min to introduce the circulating air volume 60 Nm ³ / min and external) of 10 mm).

  As a result, with respect to the amount of NMP brought into the drying furnace (residual NMP amount is 100% by weight), the evaporated NMP amount in the preheating step is 4% by weight (residual NMP amount is 96% by weight), and the evaporated NMP in the constant rate evaporation step The amount was 95% by weight (the amount of residual NMP was 1% by weight), and the amount of evaporated NMP in the reduced evaporation step was 0.97% by weight (the amount of residual NMP was 0.03% by weight).

  Further, when the NMP content remaining in the negative electrode layer when the decreasing evaporation process was completed was analyzed by gas chromatography, it was confirmed to be 0.03% by weight.

  Further, according to Example 1, the surface of the negative electrode was observed, and the adhesion strength of the electrode active material layer after pressing was measured.

[Example 11]
According to Example 10, the negative electrode slurry was applied to one side of the current collector by a coater while running a 10 μm thick copper foil current collector at a running speed of 12 m / min.

  Subsequently, the negative electrode slurry was dried by the following drying process.

First, the temperature inside the furnace in the preheating step (first drying zone) 125 ° C., the total blown air flow 20 Nm ³ / min of the upper nozzle (opening ratio 10%, D1: 25 mm) and the lower nozzle (slit width: 5 mm, D2: 10 mm) (Circulation air volume 20Nm ³ / min), furnace temperature in preheating step (second drying zone) 120 ° C., upper nozzle (opening ratio 10%, D1: 25 mm) and lower nozzle (slit width: 5 mm, D2: 10 mm) The temperature was increased under conditions of a total blown air volume of 20 Nm ³ / min (circulating air volume of 10 Nm ³ / min and an air volume of 10 Nm ³ / min introduced from the outside).

Subsequently, the furnace temperature in each zone of the constant rate evaporation step (the third drying zone to the sixth drying zone) is 120 ° C., the upper nozzle (opening ratio is 30%, D1: 15 mm), and the lower nozzle (slit width: 5 mm, D2: The constant rate evaporation was performed under the conditions of a total blown air volume 80 Nm ³ / m (10 mm) (circulated air volume 15 Nm ³ / min and air volume 65 Nm ³ / min introduced from the outside).

Furthermore, the furnace temperature in each zone of the reduction rate evaporation process (seventh drying zone and eighth drying zone) 130 ° C., upper nozzle (opening ratio 10%, D1: 15 mm) and lower nozzle (slit width: 5 mm, D2: was falling-rate evaporation under conditions of total blowoff air volume 70 Nm ³ / min (air volume 10 Nm ³ / min to introduce the circulating air volume 60 Nm ³ / min and external) of 10 mm).

  As a result, with respect to the amount of NMP brought into the drying furnace (residual NMP amount is 100% by weight), the evaporated NMP amount in the preheating step is 4% by weight (residual NMP amount is 96% by weight), and the evaporated NMP in the constant rate evaporation step The amount was 94% by weight (residual NMP amount was 2% by weight), and the amount of evaporated NMP in the decremental evaporation step was 1.97% by weight (residual NMP amount was 0.03% by weight).

  Further, when the content of NMP remaining in the negative electrode layer when the reduction evaporation process was completed was analyzed by gas chromatography, it was confirmed to be 0.03% by weight.

  Further, according to Example 1, the surface of the negative electrode was observed, and the adhesion strength of the electrode active material layer after pressing was measured.

[Example 12]
According to Example 10, the negative electrode slurry was applied to one side of the current collector by a coater while a 10 μm-thick rolled copper foil current collector was run at a running speed of 16 m / min.

  Subsequently, the negative electrode slurry was dried by the following drying process.

First, the temperature inside the furnace of the preheating step (first drying zone) is 130 ° C., and the total blown air volume of the upper nozzle (opening ratio 10%, D1: 15 mm) and the lower nozzle (slit width: 5 mm, D2: 10 mm) is 25 Nm ³ / min. (Circulation air volume 25 Nm ³ / min), furnace temperature 130 ° C. of preheating process (second drying zone), upper nozzle (opening ratio 10%, D1: 15 mm) and lower nozzle (slit width: 5 mm, D2: 10 mm) The temperature was raised under conditions of a total blown air volume of 25 Nm ³ / min (circulating air volume of 15 Nm ³ / min and an air volume of 10 Nm ³ / min introduced from the outside).

Subsequently, the furnace temperature in each zone of the constant rate evaporation step (third drying zone to sixth drying zone) 125 ° C., the upper nozzle (opening ratio 30%, D1: 15 mm) and the lower nozzle (slit width: 5 mm, D2: The constant rate evaporation was performed under the conditions of a total blown air volume of 10 Nm) of 100 Nm ³ / m (circulating air volume of 10 Nm ³ / min and an air volume of 90 Nm ³ / min introduced from the outside).

Furthermore, the furnace temperature in each zone of the reduction rate evaporation process (seventh drying zone and eighth drying zone) 135 ° C., upper nozzle (opening ratio 10%, D1: 15 mm) and lower nozzle (slit width: 5 mm, D2: 10 mm), the reduced rate evaporation was performed under the conditions of a total blown air flow rate of 100 Nm ³ / min (circulation air flow rate of 80 Nm ³ / min and an external air amount of 20 Nm ³ / min).

  As a result, with respect to the amount of NMP brought into the drying furnace (residual NMP amount is 100% by weight), the evaporated NMP amount in the preheating step is 3% by weight (residual NMP amount is 97% by weight), and the evaporated NMP in the constant rate evaporation step The amount was 94% by weight (the amount of residual NMP was 3% by weight), and the amount of evaporated NMP in the decremental evaporation step was 2.97% by weight (the amount of residual NMP was 0.03% by weight).

  Further, when the NMP content remaining in the negative electrode layer when the decreasing evaporation process was completed was analyzed by gas chromatography, it was confirmed to be 0.03% by weight.

  Further, according to Example 1, the surface of the negative electrode was observed, and the adhesion strength of the electrode active material layer after pressing was measured.

[Example 13]
In Example 12, an infrared heating furnace was incorporated in the preheating process, the furnace temperature in the preheating process (first drying zone) was 125 ° C., the upper nozzle (opening ratio 20%, D1: 50 mm), and the lower nozzle (slit width: 5 mm). , D2: 10 mm), total blown air volume 15 Nm ³ / min (circulating air volume 15 Nm ³ / min), furnace temperature in the preheating step (second drying zone) 125 ° C., upper nozzle (opening ratio 20%, D1: 50 mm) and lower nozzle (slit width: 5mm, D2: 10mm) and heating was carried out under the conditions of the total blowoff air volume 15 Nm ³ / min (air volume 10 Nm ³ / min to introduce the circulating air volume ^{5 Nm} 3 / min and external) of the. Except this, it was the same as Example 12.

[Example 14]
In Example 12, an infrared heating furnace apparatus was incorporated in the constant rate evaporation step, the furnace temperature in each zone of the constant rate evaporation step (the third drying zone to the sixth drying zone) was 115 ° C., the upper nozzle (opening ratio 40%, D1: 50%) and the lower nozzle (slit width: 5 mm, D2: 10 mm), the total blown air volume was 90 Nm ³ / m (the amount of air introduced from the outside was 90 Nm ³ / min), and constant rate evaporation was performed.

  Except this, it was the same as Example 12.

[Example 15]
In Example 12, an infrared heating furnace apparatus was incorporated into the rate reduction evaporation process, the furnace temperature in each zone of the rate reduction evaporation process (seventh drying zone and eighth drying zone), an upper nozzle (opening ratio 20%, D1: 50 mm) and a lower nozzle (slit width: 5mm, D2: 10mm) under conditions of the blowing air volume 70 Nm ³ / min from all the nozzles (air volume 10 Nm ³ / min to introduce the circulating air volume 60 Nm ³ / min and external) Decreased evaporation was performed. Except this, it was the same as Example 12.

[Example 16]
In Example 12, an infrared heating furnace apparatus was placed at a position 2.5 m from the position where the reduced heating zone was exited, and additional drying was performed at 130 ° C. Except this, it was the same as Example 12.

[Example 17]
In accordance with Example 1, the positive electrode slurry was applied to one side of the current collector by a coater while running a 20 μm thick aluminum foil current collector at a running speed of 8 m / min. Subsequently, in FIG. 1, there are four types of constant rate evaporation steps (one block is 8 m furnace with 2.5 m and the total furnace length is 20 m) and FIG. 4 (distance from upper nozzle to foil (D1): 10 to 150 mm, The positive electrode slurry was dried by the following drying process using the drying furnace indicated by the distance from the lower nozzle to the foil (D2): 10 to 75 mm.

First, the furnace temperature in each zone of the preheating process (first drying zone and second drying zone) 135 ° C., upper nozzle (opening ratio 10%, D1: 50 mm) and lower nozzle (slit width: 5 mm, D2: 10 mm) the heating was carried out under the conditions of the total blowoff air volume 50 Nm ³ / min of (air volume ^{7 Nm} 3 / min to introduce the circulating air volume 43 nm ³ / min and the outside).

Subsequently, the furnace temperature in each zone of the constant rate evaporation step 1 (third drying zone and fourth drying zone) 125 ° C., upper nozzle (opening ratio 30%, D1: 25 mm) and lower nozzle (slit width: 5 mm, D2) : 10 mm) constant rate evaporation was performed under the conditions of a total blown air volume of 29 Nm ³ / m (circulating air volume of ³ Nm ³ / min and air volume of 26 Nm ³ / min introduced from the outside).

Subsequently, the furnace temperature in each zone of the constant rate evaporation step 2 (5th drying zone and 6th drying zone), upper nozzle (opening ratio 20%, D1: 25 mm) and lower nozzle (slit width: 5 mm, D2) : 10 mm), constant rate evaporation was performed under conditions of a total blown air volume of 71 Nm ³ / m (circulating air volume of 7 Nm ³ / min and an air volume of 64 Nm ³ / min introduced from the outside).

Further, the furnace temperature in each zone of the reduction evaporation process (seventh drying zone and eighth drying zone) is 140 ° C., the upper nozzle (opening ratio 10%, D1: 100 mm) and the lower nozzle (slit width: 5 mm, D2: The reduced evaporation was performed under the conditions of a total blowing air volume of 70 Nm ³ / min (10 mm) (circulating air volume 67 Nm ³ / min and air volume ³ Nm ³ / min introduced from the outside).

  The NMP concentration sensor installed at the top of each process measures the amount of NMP discharged (evaporated) from each process, and the coating layer (the positive electrode slurry applied on the current collector) that passes through each process remains. The solvent content was calculated.

  As a result, with respect to the amount of NMP brought into the drying furnace (the amount of residual NMP is 100% by weight), the amount of NMP evaporated in the preheating step is 7% by weight (the amount of residual NMP is 93% by weight). The NMP amount is 27% by weight (the residual NMP amount is 66% by weight), the evaporated NMP amount in the constant rate evaporation step 2 is 65% by weight (the residual NMP amount is 1% by weight), and the evaporated NMP amount in the decremental evaporation step is 0 97% by weight (the amount of residual NMP was 0.03% by weight).

  Further, when the NMP content remaining in the positive electrode layer when the reduction evaporation process was completed was analyzed by gas chromatography, it was confirmed to be 0.03% by weight.

  Further, according to Example 1, the surface of the positive electrode was observed, and the adhesion strength of the electrode active material layer after pressing was measured.

[Example 18]
In accordance with Example 1, the positive electrode slurry was applied to one side of the current collector by a coater while running a 20 μm thick aluminum foil current collector at a running speed of 16 m / min.

  Subsequently, the positive electrode slurry was dried by the following drying process.

First, the furnace temperature in the preheating step (first drying zone) 140 ° C., the total blown air volume 40 Nm ³ / min of the upper nozzle (opening ratio 10%, D1: 15 mm) and the lower nozzle (slit width: 5 mm, D2: 10 mm) (Circulation air volume 40Nm ³ / min), furnace temperature in preheating process (second drying zone) 135 ° C., upper nozzle (opening ratio 10%, D1: 15 mm) and lower nozzle (slit width: 5 mm, D2: 10 mm) the heating was carried out under the conditions of the total blowoff air volume 50 Nm ³ / min (air volume 30 Nm ³ / min to introduce the circulating air volume 20 Nm ³ / min and the outside).

Subsequently, the furnace temperature in each zone of the constant rate evaporation step 1 (third drying zone and fourth drying zone), an upper nozzle (aperture ratio 35%, D1: 25 mm) and a lower nozzle (slit width: 5 mm, D2) : 10 mm) constant rate evaporation was performed under the conditions of a total blown air volume of 58 Nm ³ / m (circulating air volume of 6 Nm ³ / min and an air volume of 52 Nm ³ / min introduced from the outside).

Subsequently, the furnace temperature in each zone of the constant rate evaporation step 2 (the fifth drying zone and the sixth drying zone), an upper nozzle (aperture ratio 30%, D1: 25 mm) and a lower nozzle (slit width: 5 mm, D2) : 10 mm), constant-rate evaporation was performed under the conditions of an air flow rate of 142 Nm ³ / m from all nozzles (circulation air rate 19 Nm ³ / min and an air amount 123 Nm ³ / min introduced from the outside).

Furthermore, the furnace temperature in each zone of the reduction rate evaporation process (seventh drying zone and eighth drying zone) is 140 ° C., the upper nozzle (opening ratio 10%, D1: 15 mm) and the lower nozzle (slit width: 5 mm, D2: was falling-rate evaporation under conditions of a balloon air flow 120 Nm ³ / min from all the nozzles (air volume 15 Nm ³ / min to introduce the circulating air volume 105 Nm ³ / min and external) of 10 mm).

  As a result, with respect to the amount of NMP brought into the drying furnace (residual NMP amount is 100% by weight), the evaporation NMP amount in the preheating step is 3% by weight (residual NMP amount is 97% by weight), and the evaporation in the constant rate evaporation step 1 The NMP amount is 27% by weight (the residual NMP amount is 66% by weight), the evaporated NMP amount in the constant rate evaporation step 2 is 65% by weight (the residual NMP amount is 1% by weight), and the evaporated NMP amount in the decremental evaporation step is 2. 97% by weight (the amount of residual NMP was 0.03% by weight).

  Further, when the NMP content remaining in the positive electrode layer when the reduction evaporation process was completed was analyzed by gas chromatography, it was confirmed to be 0.03% by weight.

  Further, according to Example 1, the surface of the positive electrode was observed, and the adhesion strength of the electrode active material layer after pressing was measured.

[Comparative Example 1]
According to Example 1, the paint was applied to one side of the current collector by a die coater while running a 20 μm thick aluminum foil current collector at a running speed of 8 m / min.

  Subsequently, the positive electrode slurry was dried by the following drying process.

First, the furnace temperature in each zone of the preheating step (1-2) is 140 ° C., and the total blown air volume of the upper nozzle (slit width: 5 mm, D1: 50 mm) and the lower nozzle (slit width: 5 mm, D2: 10 mm) is 100 Nm ^3. The temperature was raised under the conditions of / min (circulation air volume 50 Nm ³ / min and air volume 50 Nm ³ / min introduced from outside).

Subsequently, the furnace temperature in each zone of the constant rate evaporation step (third drying zone to sixth drying zone) 135 ° C., the upper nozzle (slit width: 5 mm, D1: 25 mm) and the lower nozzle (slit width: 5 mm, D2: The constant rate evaporation was performed under the conditions of an air flow rate of 200 Nm ³ / m from all nozzles (10 mm) (circulation air flow rate 25 Nm ³ / min and air amount 175 Nm ³ / min introduced from the outside).

Furthermore, the furnace temperature in each zone of the reduction rate evaporation process (seventh drying zone and eighth drying zone) is 140 ° C., the upper nozzle (slit width: 5 mm, D1: 25 mm) and the lower nozzle (slit width: 5 mm, D2: was falling-rate evaporation under conditions of a balloon air flow 120 Nm ³ / min from all the nozzles (air volume 15 Nm ³ / min to introduce the circulating air volume 105 Nm ³ / min and external) of 10 mm).

  As a result, with respect to the amount of NMP brought into the drying furnace (the amount of residual NMP is 100% by weight), the amount of evaporated NMP in the preheating step is 21% by weight (the amount of residual NMP is 79% by weight), and the amount of evaporated NMP in the constant rate evaporation step The amount was 78% by weight (residual NMP amount was 1% by weight), and the evaporated NMP amount in the reduced evaporation step was 0.97% by weight (residual NMP amount was 0.03% by weight).

  Further, when the NMP content remaining in the positive electrode layer when the reduction evaporation process was completed was analyzed by gas chromatography, it was confirmed to be 0.03% by weight.

  Further, according to Example 1, the surface of the positive electrode was observed, and the adhesion strength of the electrode active material layer after pressing was measured.

[Comparative Example 2]
According to Example 10, the paint was applied to one side of the current collector by a die coater while running a rolled copper foil current collector having a thickness of 10 μm at a running speed of 8 m / min.

  Subsequently, the negative electrode slurry was dried by the following drying process.

First, the furnace temperature in the preheating step (1-2) is 140 ° C., the total blown air volume of the upper nozzle (opening ratio 5%, D1: 25 mm) and the lower nozzle (slit width: 5 mm, D2: 10 mm) is 50 Nm ³ / min ( the heating was carried out under the conditions of air volume 20 Nm ³ / min) for introducing the amount of circulating air 30 Nm ³ / min and the outside.

Subsequently, the furnace temperature in each zone of the constant rate evaporation step (the third drying zone to the sixth drying zone) 130 ° C., the upper nozzle (opening ratio 5%, D1: 25 mm) and the lower nozzle (slit width: 5 mm, D2: The constant rate evaporation was performed under the conditions of an air flow rate of 100 Nm ³ / m from all the nozzles (10 mm) (circulation air flow rate 10 Nm ³ / min and air amount 90 Nm ³ / min introduced from the outside).

Furthermore, the furnace temperature in each zone of the reduction rate evaporation process (seventh drying zone and eighth drying zone) 135 ° C., upper nozzle (opening ratio 5%, D1: 25 mm) and lower nozzle (slit width: 5 mm, D2: was falling-rate evaporation under conditions of a balloon air flow 100 Nm ³ / min from all the nozzles (air volume 20 Nm ³ / min to introduce the circulating air volume 80 Nm ³ / min and external) of 10 mm).

  As a result, with respect to the amount of NMP brought into the drying furnace (the amount of residual NMP is 100% by weight), the amount of evaporated NMP in the preheating step is 10% by weight (the amount of residual NMP is 90% by weight), and the amount of evaporated NMP in the constant rate evaporation step The amount was 89% by weight (the amount of residual NMP was 1% by weight), and the amount of evaporated NMP in the decreasing evaporation step was 0.97% by weight (the amount of residual NMP was 0.03% by weight).

Further, when the NMP content remaining in the positive electrode layer when the reduction evaporation process was completed was analyzed by gas chromatography, it was confirmed to be 0.03% by weight.
Further, according to Example 10, the surface of the negative electrode was observed, and the adhesion strength of the electrode active material layer after pressing was measured.

  Table 4 shows the ratio of the integrated strength of the binder in the vicinity of the current collector to the adhesion strength and the integrated strength of all the binders in Examples 1 to 8, 17, 18 and Comparative Example 1. . From Table 4, by using the electrode manufacturing apparatus according to the present invention, the ratio of the integrated strength of the binder in the vicinity of the current collector to the integrated strength of all the binders is 30% or more, and the adhesion A high-strength electrode could be manufactured.

  Table 5 shows the adhesion strength in Examples 9 to 16 and Comparative Example 2 and the ratio of the average D / G value (Rs) in the vicinity of the electrode layer to the average D / G value (Rb) in the center of the electrode layer (Rs / Rb). From Table 5, by using the electrode manufacturing apparatus according to the present invention, it was possible to manufacture an electrode having Rs / Rb of 2 or less and high adhesion strength.

1 electrode manufacturing equipment,
30 drying oven,
33 perforated plate nozzle,
55 Infrared heating element,
100, 200 electrodes,
101, 201 current collector,
102, 202 coating layer,
103, 203 electrode layer,
110, 210 electrode slurry,
111, 211 active material,
112, 212 binder,
113, 213 conductivity imparting agent,
114, 214 solvent,
A01 Current collector vicinity,
A02 Electrode layer surface vicinity portion,
A03 center of electrode layer,
S04 Preheating process,
S05 constant rate evaporation process,
S06 Decreasing evaporation process

Claims (11)

An electrode in which an electrode layer overlaps a current collector,
The region of the electrode layer where the current collector overlaps is an electrode having a higher component concentration of the binder contained in the electrode layer than the region of the surface layer opposite to the side where the current collector overlaps.   When the total thickness of the electrode layer is 1, Raman spectroscopy of all the binders in the vicinity of the current collector, which is a region from the side where the current collector of the electrode layer overlaps to 1/4 The electrode according to claim 1, wherein 20 to 40% of the integrated intensity, which is an integrated value of the peak intensity appearing in a specific wavelength band when measured in step 1, is present.   The integrated current strength of the binder is higher in the vicinity of the current collector than in the vicinity of the electrode layer surface layer, which is a region from the surface layer side opposite to the side where the current collector overlaps the electrode layer to 1/4. Item 3. The electrode according to Item 2.   When the total thickness of the electrode layer is 1, from 1/4 to the electrode layer surface vicinity, which is a region from the surface layer side in contact with the air of the electrode layer to 1/4, from the surface layer side as a reference The electrode according to any one of claims 1 to 3, wherein there is a region where the concentration of the conductivity-imparting agent is higher than the central portion of the electrode layer, which is a region up to 1.   When the average D / G value that is the intensity ratio of the peak of the D band to the G band of carbon measured by Raman spectroscopy is Rs in the vicinity of the surface of the electrode layer and Rb in the center of the electrode layer, The electrode according to claim 4, satisfying a relationship of 2.0 ≧ Rs / Rb. An application layer formed by applying an electrode slurry containing an active material, a binder, a conductivity-imparting agent and a solvent to a current collector is dried in a drying furnace, and the electrode layer is provided on the current collector. An electrode manufacturing method for manufacturing overlapping electrodes,
A preheating step for preheating the electrode slurry;
A constant rate evaporation step in which the drying rate of the electrode slurry is constant;
A decreasing rate evaporation process in which the drying rate of the electrode slurry gradually decreases depending on the decrease in the solvent content of the electrode slurry;
An electrode manufacturing method comprising:   In the preheating step, the constant rate evaporation step, and the reduction rate evaporation step, the amount of the solvent remaining in the electrode slurry when each step is completed is 100 to 90% by weight, 95 to 1% by weight, and 5 to 0.01, respectively. The electrode manufacturing method according to claim 6, which is in the range of%.   The constant-rate evaporation step includes a first constant-rate evaporation step and a second constant-rate evaporation step, and the amount of solvent remaining in the electrode slurry when each step is completed is 95 to 65% by weight and 65 to 1% by weight, respectively. The electrode manufacturing method according to claim 7, which is in the range of.   The electrode manufacturing method according to any one of claims 6 to 8, wherein the amount of the solvent remaining in the electrode slurry after the reduction evaporation step is 0.1 wt% or less. An application layer formed by applying an electrode slurry containing an active material, a binder, a conductivity-imparting agent and a solvent to a current collector is dried in a drying furnace, and the electrode layer is provided on the current collector. It is an electrode manufacturing apparatus used for the electrode manufacturing method of any one of Claims 6-9 which manufactures the electrode which overlaps,
Production of an electrode having a perforated plate nozzle having a large number of holes at the outlet of hot air for heating and drying the surface on which the electrode slurry coating layer is formed with hot air, and the perforated plate nozzle has an aperture ratio of 10% or more apparatus.   The electrode manufacturing apparatus according to claim 10, further comprising an infrared heating element for heating and drying the surface on which the coating layer of the electrode slurry is formed.

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