Method for manufacturing electrode and electrode manufacturing device

Abstract

To suppress the rise of the temperature of a workpiece of a collector by radiation of energy particles.SOLUTION: The method for manufacturing an electrode includes: a radiation step of performing radiation processing of radiating energy particles on at least a surface of a collector workpiece 40 forming an electrode; and an application step of applying an active material slurry 50 on the surface of the collector workpiece on which the radiation processing was performed. In the radiation step, radiation of the energy particles on the same radiation target region of the collector workpiece 40 for a predetermined radiation time is performed in plural stages and a radiation stop time in which the radiation of energy particles on the same radiation target region is stopped is provided between one radiation and the next radiation in plural times of radiations of the energy particles.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method and apparatus for manufacturing an electrode for a secondary battery. [Background technology]

[0002] In recent years, the electrodes of lithium-ion secondary batteries generally have a structure in which an active material slurry is applied onto a current collector (e.g., a metal foil such as aluminum foil, copper foil, or stainless steel foil). As the active material, oxides or phosphate compounds of various metals such as lithium, nickel, cobalt, manganese, and iron are used for the positive electrode, and carbon-based materials such as graphite and hard carbon, and lithium titanate are used for the negative electrode. These active material powders, a binder for binding them to the current collector, and a conductive assistant such as acetylene black for obtaining high conductivity are kneaded with a solvent to form an active material slurry. In addition, lithium-ion secondary batteries are rapidly increasing in current, capacity, and speed. The contact resistance (interface resistance) between the current collector and the active material slurry is an obstacle to this. Therefore, there is a demand for reducing the contact resistance.

[0003] It is known that the adhesion between the active material slurry and the current collector is a major factor in increasing the contact resistance. In other words, if the adhesion is poor, the active material peels off or floats during charging and discharging, causing a significant increase in resistance. As a result, the deterioration of the secondary battery progresses, the charge and discharge characteristics deteriorate, and the life of the secondary battery is shortened.

[0004] To prevent this, attempts have been made to improve the adhesion to the active material slurry by subjecting the current collector surface to a surface modification treatment such as hydrophilization or surface roughening by carbon coating. Among these, the hydrophilization treatment involves irradiating the surface with energy particles, such as vacuum ultraviolet light in the presence of oxygen or atmospheric pressure plasma (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2012-94343 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, irradiation of energy particles such as vacuum ultraviolet light or atmospheric plasma is accompanied by a temperature rise in the current collector, and if it is performed continuously for a long time, the current collector will expand due to the temperature rise, or the current collector will expand unevenly due to temperature variations within the irradiated surface. This temperature rise is even more pronounced for metal current collectors with carbon coating on the surface, as the light absorption rate increases. In addition, strong light emission is generated when plasma is generated, and it is even more pronounced in atmospheric plasma irradiation treatment in which both plasma and light are incident on the workpiece.

[0007] If the next step of applying the active material slurry is carried out in a state accompanied by an increase in temperature, the current collector will rapidly cool and shrink after application because the active material slurry is at room temperature, which is lower than the temperature of the current collector, and the shrinkage will occur unevenly due to the above-mentioned variations. This causes the active material slurry to wrinkle or peel off partially, increasing the interface resistance and causing performance degradation.

[0008] In addition, since the irradiation process of energetic particles in the presence of oxygen makes the surface of the current collector hydrophilic through an oxidation reaction that generates active oxygen, if the temperature is high during this process, the oxidation will progress inside the current collector and the surface oxide film will grow more than necessary, which will increase the resistance of the oxide film and cause the performance of the secondary battery to deteriorate. The present invention has been made in view of the above, and an object of the present invention is to suppress a temperature rise in a current collector workpiece due to irradiation with energetic particles. [Means for solving the problem]

[0009] In order to solve the above problems, one aspect of the electrode manufacturing method according to the present invention is a method for manufacturing an electrode for a secondary battery, comprising an irradiation step of irradiating at least one surface of a workpiece of a current collector constituting the electrode with energy particles to perform irradiation treatment, and a coating step of coating a slurry containing an active material onto the surface of the workpiece that has been irradiated with the energy particles in the irradiation step. In addition, in the irradiation step, the energy particles are irradiated to the same irradiated region of the workpiece for a predetermined irradiation time in multiple rounds, and an irradiation pause time is provided between each irradiation of the multiple irradiations of the energy particles and the next irradiation of the multiple irradiations of the energy particles to pause the irradiation of the energy particles to the same irradiated region.

[0010] As a result, during the irradiation pause time between each irradiation and the next irradiation in the multiple irradiations, the irradiation of the energy particles to the same irradiated area is paused, so that the work can be cooled during that time. As a result, the temperature rise of the work due to the irradiation process can be suppressed compared to the case where the energy particles are continuously irradiated to the same irradiated area for a predetermined irradiation time. Therefore, the increase in the resistance of the surface oxide film due to the increase in the thickness of the surface oxide film caused by the temperature rise of the work can be reduced, and the performance deterioration of the secondary battery can be reduced. In addition, when the active material slurry is applied continuously after the irradiation process, the shrinkage of the work due to the temperature difference between the active material slurry and the work can be reduced, so that the increase in the interface resistance due to the occurrence of wrinkles and peeling can be reduced. In addition, since the irradiation process can impart wettability to the surface of the work, by applying the active material slurry to the surface after the wettability is imparted, the adhesion with the active material slurry can be improved and the interface resistance can be reduced. In the above-described electrode manufacturing method, in the irradiation step, the irradiation pause time may be controlled so that the temperature of the workpiece after the temperature increase due to the irradiation of the energetic particles becomes equal to or lower than a predetermined temperature.

[0011] As a result, by setting the specified temperature to, for example, a temperature at which shrinkage of the collector workpiece due to application of the active material slurry is unlikely to occur, or a temperature at which the thickness of the surface oxide film is unlikely to increase, it is possible to more reliably reduce the increase in interface resistance and the increase in resistance of the surface oxide film due to an increase in the temperature of the workpiece. In the above-described electrode manufacturing method, a plurality of types of radiation pause times having different time lengths may be set in the radiation step. As a result, in an irradiation process divided into multiple steps, the temperature rise after each irradiation changes and the cooling conditions change, so that the temperature rise of the workpiece can be suppressed more efficiently than, for example, setting all irradiation pause times of the same length. In the above-described electrode manufacturing method, in irradiating the same region with the energetic particles a plurality of times, a longer radiation pause time may be set for each subsequent irradiation. Here, the temperature after irradiation with energetic particles becomes higher in later rounds due to residual heat, so by making the cooling time longer in later rounds, the temperature rise of the workpiece can be more efficiently suppressed. In the above-mentioned electrode manufacturing method, the energetic particles may be photons having a wavelength of 200 nm or less, or plasma particles. This makes it possible to perform an irradiation process that can modify (make hydrophilic) the workpiece surface while suppressing a rise in the workpiece temperature, for example, by irradiating the workpiece with photons of vacuum ultraviolet light or atmospheric pressure plasma particles.

[0012] In the above-mentioned electrode manufacturing method, the slurry contains the active material, a conductive assistant, and a binder, and when the sum of the compounding ratios of the active material, the conductive assistant, and the binder is 100[%], the compounding ratio X[%] of the conductive assistant is within a range of 0.01 to 0.01. <X≦5としてもよい。 This makes it possible to reduce the interface resistance while suppressing a decrease in the capacity of the secondary battery due to an increase in the conductive additive, thereby further enhancing the effect of improving the performance of the secondary battery through the irradiation treatment.

[0013] On the other hand, one aspect of the electrode manufacturing apparatus according to the present invention is an electrode manufacturing apparatus for manufacturing an electrode for a secondary battery, comprising: an energy particle source that radiates energy particles, a movement mechanism that moves at least one of a current collector workpiece constituting the electrode and the energy particle source, and a control unit that controls the energy particle source and the movement mechanism. In addition, the control unit controls the movement mechanism so that an irradiation area of ​​the energy particle source moves along or relatively to a surface of the workpiece, and controls the energy particle source to irradiate the same irradiated area of ​​the workpiece with the energy particles for a predetermined irradiation time in multiple rounds, and to provide an irradiation pause time between each irradiation and the next irradiation of the multiple irradiations of the energy particles, during which irradiation of the energy particles to the same irradiated area is paused.

[0014] According to this configuration, the irradiation of the energy particles is paused during the irradiation pause time between each irradiation in the multiple irradiations, so that the workpiece can be cooled during that time. This makes it possible to suppress the temperature rise of the workpiece due to the irradiation, compared to the case where the same irradiated area is continuously irradiated with the energy particles for a predetermined irradiation time. As a result, it is possible to reduce the increase in the resistance of the surface oxide film due to the increase in the thickness of the surface oxide film caused by the temperature rise of the workpiece, and to reduce the performance deterioration of the secondary battery. In addition, when the active material slurry is applied continuously after the irradiation process, it is possible to reduce the shrinkage of the workpiece due to the temperature difference between the active material slurry and the workpiece, so that it is possible to reduce the increase in the interface resistance due to the occurrence of wrinkles and peeling.

[0015] Moreover, one aspect of the electrode manufacturing apparatus according to the present invention is an electrode manufacturing apparatus for manufacturing an electrode for a secondary battery, comprising a plurality of energy particle sources that radiate energy particles, a transport mechanism that transports a workpiece of a current collector that constitutes the electrode, and a control unit that controls the plurality of energy particle sources and the transport mechanism. In addition, the plurality of energy particle sources are arranged at predetermined intervals along the longitudinal direction of the workpiece, and the transport mechanism is configured to transport the workpiece to the irradiation positions of the energy particles of each of the energy particle sources in sequence. Furthermore, the control unit controls the transport mechanism to a transport speed that can irradiate the energy particles to the same irradiated region of the workpiece during divided irradiation times obtained by dividing a predetermined irradiation time required for processing into the same number of energy particle sources at each irradiation position, and to a transport speed that can form an irradiation pause time during which the irradiation is paused for the same irradiated region in the section of the predetermined interval.

[0016] According to this configuration, the workpiece is transported at a transport speed that forms an irradiation pause time in a section with a predetermined interval, so that the workpiece can be cooled in this section. This makes it possible to suppress the temperature rise of the workpiece due to irradiation, compared to the case where the same irradiated area is continuously irradiated with energetic particles for a predetermined irradiation time. As a result, it is possible to reduce the increase in resistance of the surface oxide film due to the increase in the thickness of the surface oxide film caused by the temperature rise of the workpiece, and to reduce the performance deterioration of the secondary battery. In addition, when the active material slurry is applied continuously after the irradiation process, it is possible to reduce the shrinkage of the workpiece due to the temperature difference between the active material slurry and the workpiece, so that it is possible to reduce the increase in interface resistance due to the occurrence of wrinkles and peeling. In the electrode manufacturing apparatus, the predetermined interval may be configured as a plurality of intervals having different lengths. According to this configuration, it is possible to set a plurality of types of irradiation pause times with different lengths depending on the length of the interval while keeping the transport speed constant. Also, it is possible to suppress the temperature rise of the workpiece more efficiently than, for example, setting all irradiation pause times of the same length. Furthermore, in the electrode manufacturing apparatus, the plurality of types of intervals may be set such that the intervals of the energy irradiation source disposed downstream are longer than the intervals of the energy irradiation source disposed upstream. With this configuration, the temperature after irradiation with energetic particles becomes higher in later rounds due to residual heat, so by making the cooling time longer in later rounds, the temperature rise of the workpiece can be more efficiently suppressed. Furthermore, in the electrode manufacturing apparatus, the energetic particle source may be an ultraviolet light radiation source that radiates photons with a wavelength of 200 nm or less, or a plasma radiation source that radiates atmospheric pressure plasma particles. According to this configuration, the workpiece surface can be hydrophilized while suppressing an increase in the workpiece temperature. The electrode manufacturing apparatus may further include a coating mechanism that coats the surface of the workpiece after irradiation with the energetic particles with a slurry containing an active material. According to this configuration, the active material slurry can be applied to the surface of the workpiece after modification, where the temperature rise is suppressed. Effect of the Invention

[0017] In the present invention, it is possible to suppress the temperature rise of the current collector workpiece caused by irradiation with energetic particles. [Brief description of the drawings]

[0018] [Figure 1] 1 is a schematic diagram showing a basic configuration of a lithium-ion secondary battery 30 according to a first embodiment. [Diagram 2] 1A to 1C are diagrams illustrating an example of a process for manufacturing an electrode of a lithium ion secondary battery 30. [Diagram 3] FIG. 2 is a diagram showing an example of a schematic configuration of an electrode manufacturing apparatus 1 used in an irradiation step and a coating step. [Figure 4] 1 is a diagram showing an example of the positional relationship between an irradiation area of ​​an energetic particle source 11 and a current collector workpiece 40. FIG. [Diagram 5] 4 is a flowchart showing an electrode manufacturing control process according to the first embodiment. [Figure 6] FIG. 13 is a diagram showing a change in temperature of a current collector workpiece when the current collector workpiece is continuously irradiated with vacuum ultraviolet light for an irradiation time required for surface modification. [Figure 7] FIG. 11 is a diagram showing a temperature change of a current-collector workpiece when irradiation with vacuum ultraviolet light for an irradiation time required for surface modification is performed by the irradiation method according to the first embodiment. [Figure 8A] FIG. 2 is a diagram showing an example of a schematic configuration of an electrode manufacturing apparatus 2 used in an irradiation step and a coating step. [Figure 8B] 1 is a diagram showing an example of the positional relationship between an irradiation area of ​​an energetic particle source 22 and a current collector workpiece 60. FIG. [Figure 9] 13 is a flowchart showing an electrode manufacturing control process according to a second embodiment. [Figure 10] FIG. 13 is a diagram showing a change in temperature of a current collector workpiece. [Figure 11] FIG. 13 is a diagram showing the rated capacity of a secondary battery cell after charging and discharging when the compounding ratio X of the conductive assistant 36 in the active material slurry 50 is 2%. [Figure 12] FIG. 13 is a diagram showing the rated capacity of a secondary battery cell after charging and discharging when the compounding ratio X of the conductive assistant 36 in the active material slurry 50 is set to 5%. [Figure 13] FIG. 13 is a diagram showing a schematic configuration of an electrode manufacturing apparatus 1A according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] First Embodiment [Outline of lithium-ion secondary batteries] A first embodiment of the present invention will be described below with reference to the drawings. Figures 1 to 7 are diagrams showing the first embodiment. In the first embodiment, a method for manufacturing an electrode for a secondary battery and an electrode manufacturing apparatus used in a process for manufacturing an electrode for a secondary battery will be described. In the first embodiment, the secondary battery is a lithium ion secondary battery. First, an overview of the lithium ion secondary battery will be given. FIG. 1 is a schematic diagram showing the basic configuration of a lithium ion secondary battery 30. As shown in FIG. As shown in FIG. 1, a lithium ion secondary battery 30 includes a negative electrode 31, a separator 32, a positive electrode 33, and an electrolyte solution . The negative electrode 31 and the positive electrode 33 are disposed facing each other with a separator 32 for preventing short circuits therebetween, and an electrolyte 34 fills the space between the negative electrode 31 and the separator 32 and the space between the positive electrode 33 and the separator 32 . The negative electrode 31 has a negative electrode current collector 31a and a negative electrode active material layer 31b provided on the surface of the negative electrode current collector 31a facing the positive electrode 33, and the positive electrode 33 has a positive electrode current collector 33a and a positive electrode active material layer 33b provided on the surface of the positive electrode current collector 33a facing the negative electrode 31. The negative electrode current collector 31a is made of a metal foil such as a copper foil or a stainless steel foil. The negative electrode active material layer 31b is configured to contain, for example, a carbon-based material such as graphite or hard carbon, an active material such as lithium titanate, a conductive assistant such as acetylene black, and the like. The positive electrode current collector 33a is made of a metal foil such as an aluminum foil or a stainless steel foil. The positive electrode active material layer 33b is configured to contain active materials such as oxides and phosphate compounds of various metals such as lithium, nickel, cobalt, manganese, and iron, a conductive assistant, and the like. The electrolyte 34 is made by dissolving an electrolyte salt such as LiPF6 or LiBF4 in a mixed solvent of a cyclic carbonate ester and a chain carbonate ester, for example. The negative electrode active material layer 31b and the positive electrode active material layer 33b are formed by applying an active material slurry to the negative electrode current collector 31a and the positive electrode current collector 33a, respectively.

[0020] Specifically, in the case of positive electrode active material layer 33b as an example, the active material layer is configured to include active material 35, conductive assistant 36, binder 37, and voids 38. In addition, since a drying and compression process or a compression process is performed after the active material slurry is applied, positive electrode active material layer 33b also includes active material 35c that is cracked due to compression.

[0021] Here, the drying and compression process involves drying the current collector after applying the active material slurry in a thermostatic chamber, etc., and then pressing the active material slurry onto the current collector using a roll press, etc., after drying. This process reduces the interface resistance and adjusts the density of the slurry. In recent years, semi-solid electrodes that do not require drying have appeared, and compression may be performed without drying. For this reason, the drying process is selected appropriately depending on the structure and type of battery. [Electrode manufacturing method] Next, a method for manufacturing electrodes of the lithium ion secondary battery 30 will be described. FIG. 2 is a diagram showing an example of a process for manufacturing an electrode of the lithium ion secondary battery 30. As shown in FIG.

[0022] First, in a preparation step S10, a work 40 (hereinafter referred to as "current collector work 40") of the negative electrode current collector 31a or the positive electrode current collector 33a is prepared. In the example of FIG. 2, the current collector work 40 has a long strip shape, which is wound up in a roll by a reel. This roll-shaped current collector work 40 is transported by a guide roller (not shown) from an upstream feed reel through the irradiation area and coating area of ​​the energetic particle source 11 and the coating mechanism 12 to a downstream take-up reel. The arrow in FIG. 2 indicates the transport direction. Here, the irradiation area is the area of ​​the irradiation position where the energetic particle source 11 irradiates the surface of the current collector workpiece 40 with energetic particles, and the application area is the area of ​​the application position where the application mechanism 12 applies the active material slurry 50 to the surface of the current collector workpiece 40.

[0023] Next, in an irradiation step S11, at least one surface of the current-collector workpiece 40 transported by the guide rollers is subjected to an irradiation treatment (surface modification treatment) in which energy particles are irradiated from the energy particle source 11. This modifies the surface of the current-collector workpiece 40 to which the active material slurry 50 is applied (hereinafter referred to as the "applied surface"). Specifically, the surface modification is a modification that makes the coating surface of the current-collector workpiece 40 hydrophilic (imparts wettability) to reduce the contact resistance (interface resistance) between the coating surface and the active material slurry 50. Here, the energetic particle source corresponds to, for example, an ultraviolet light radiation source that emits photons with a wavelength of 200 nm or less, a plasma radiation source that emits plasma particles, and the like. In the irradiation process of S11, in order to suppress a rise in temperature of the current collector workpiece 40, the irradiation of the energy particles is performed in multiple rounds for the irradiation time required for surface modification (hydrophilization) of the irradiated area of ​​the coating surface of the current collector workpiece 40. This is an irradiation method devised by the inventors based on their discovery that surface modification treatment (hydrophilization treatment) by vacuum ultraviolet light or atmospheric pressure plasma irradiation treatment does not depend on the irradiation energy value of vacuum ultraviolet light or atmospheric pressure plasma, but depends on the cumulative irradiation amount.

[0024] Specifically, this irradiation method irradiates the same irradiated area with energy particles in divided irradiation times obtained by dividing the necessary irradiation time into the same number of irradiations. In addition, this method provides an irradiation pause time between each irradiation and the next irradiation, during which the irradiation of the energy particles is paused. In other words, the same irradiated area is not irradiated with energy particles continuously for the necessary irradiation time, but is irradiated in multiple times with an irradiation pause time in between.

[0025] For example, if the required irradiation time is 6 seconds and the number of irradiations is 3, the divided irradiation time is, for example, 2 seconds, which is "6 seconds / 3 times". Note that the divided irradiation time is not limited to this configuration, and may be set to different time lengths such as 3 seconds, 2 seconds, and 1 second, as long as it is divided into 3 times.

[0026] The irradiation pause time is set so that the temperature of the current collector workpiece 40 after the temperature rise due to the irradiation of the energetic particles is equal to or lower than a predetermined temperature. For example, the irradiation pause time is set to 4 seconds after the first irradiation and 6 seconds after the second irradiation. The irradiation pause time is set to an appropriate time based on the temperature measurement results after irradiation in, for example, a test run. Hereinafter, the irradiation method of the present invention in the irradiation process in S11 above will be referred to as a "fractionated irradiation method." Next, in S12 which is a coating step, active material slurry 50 is applied by coating mechanism 12 onto the surface to be coated of current-collector workpiece 40 after irradiation treatment (surface modification). Here, for example, a die coater, a comma coater, a reverse roll coater, a gravure coater, etc. can be used as the coating mechanism 12. After being coated with the active material slurry 50, the current collector workpiece 40 is wound up on a take-up reel. Also, after applying the active material slurry 50, the current collector workpiece 40 may be primarily dried and then wound up on a take-up reel, for example. Next, in S13 which is a drying step, the current collector workpiece 40 wound around the take-up reel is transported into the thermostatic chamber 14, and the current collector workpiece 40 is dried in the thermostatic chamber 14. For example, the current collector workpiece 40 is dried in the thermostatic chamber 14 for several days. When a semi-solid electrode is to be manufactured, the drying step S13 is not carried out and the process proceeds to the next compression step S14.

[0027] Next, in a compression step S14, the active material slurry 50 applied to the current-collector workpiece 40 is compressed by a roll-press type compression mechanism 15. This forms a compressed active material slurry 50'. Here, the roll-press type is a compression type in which the current-collector workpiece 40 is poured between two rotating rollers and compressed into a linear shape.

[0028] As the compression mechanism 15, in addition to a roll press type device, there is also a full press type device that compresses the entire surface of the current collector workpiece 40 at once with a plate-like body. In the case of the current collector workpiece 40 wound in a roll shape, the roll press type is mainly used, but a full press type device can be used depending on the size and shape of the current collector workpiece. [Configuration of electrode manufacturing device] FIG. 3 is a diagram showing an example of a schematic configuration of an electrode manufacturing apparatus 1 used in the irradiation step S11 and the application step S12.

[0029] The electrode manufacturing apparatus 1 includes a transport mechanism 10 that transports the current collector workpiece 40, energy particle sources 11a, 11b, and 11c that radiate energy particles, and a coating mechanism 12 that coats the surface-modified current collector workpiece 40 with active material slurry 50. In addition, the apparatus includes a control unit 13 that controls the operations of the transport mechanism 10, the energy particle sources 11a to 11c, and the coating mechanism 12. The arrows in FIG. 3 indicate the transport direction of the current collector workpiece 40. Hereinafter, the energetic particle sources 11a to 11c will be simply referred to as "energetic particle source 11" when there is no need to distinguish between them. The transport mechanism 10 includes a feed reel 10a, a plurality of guide rollers 10b, and a take-up reel 10c. The feed reel 10a is a reel for feeding the long, strip-shaped current collector workpiece 40 wound around the feed reel 10a to the guide rollers 10b. The guide rollers 10b are rollers for transporting the current collector workpiece 40 wound around the feed reel 10a, in this order, to the irradiation areas of the energetic particle sources 11a to 11c, the coating area of ​​the coating mechanism 12, and the take-up reel 10c. The take-up reel 10 c is a reel that winds up the current collector workpiece 40 after the active material slurry 50 has been applied by the application mechanism 12 .

[0030] The transport mechanism 10 may include a tension control mechanism that adjusts the current collector workpiece 40 so that a predetermined tension is applied to the current collector workpiece 40. The tension control mechanism may be, for example, a dancer roll type automatic tension control device. The transport mechanism 10 may also include a position adjustment mechanism that adjusts the position of the current collector workpiece 40 in the width direction. The position adjustment mechanism may be, for example, an EPC (edge ​​position control) that combines an edge inspection device and a position correction device.

[0031] The energy particle sources 11a to 11c are arranged at predetermined intervals along the longitudinal direction of the current collector workpiece 40. Specifically, as shown in FIG. 3, the energy particle source 11a is arranged at the position closest to the feed reel 10a (upstream side), and the energy particle source 11b is arranged at an interval L1 from the energy particle source 11a. Further, the energy particle source 11c is arranged at an interval L2 (L1 < L2) from the energy particle source 11b.

[0032] The energy particle source 11 can be composed of an ultraviolet light source that emits photons with a wavelength of 200 [nm] or less or a plasma source that emits plasma particles. The energy particle sources 11a to 11c can be, for example, xenon excimer lamps that emit vacuum ultraviolet light with a central wavelength of 172 [nm]. Further, the energy particle sources 11a to 11c can be, for example, atmospheric pressure plasma devices that emit atmospheric pressure plasma particles. In the following description, the energy particle sources 11a to 11c are ultraviolet light sources that emit vacuum ultraviolet light. Also, the number of the energy particle sources 11 is not limited to three of the energy particle sources 11a to 11c, and may be composed of two depending on the type of the radiation source and the number of irradiations to the same region, or may be composed of four or more. The coating mechanism 12 is a mechanism for coating the active material slurry 50 on the coated surface after the surface modification of the current collector workpiece 40. The coating mechanism 12 can be, for example, a die coater.

[0033] The control unit 13 includes a processor that controls the entire electrode manufacturing apparatus 1 based on a control program, and a ROM (Read Only Memory) that stores the control program, setting data, etc. In addition, it includes a RAM (Random Access Memory) for storing data read from the ROM and calculation results necessary in the calculation process of the processor, and an I / F (interface) for mediating data input / output to an external device. These are connected to each other via a bus, which is a signal line for transferring data, so that data can be exchanged. The control unit 13 is electrically connected to the transport mechanism 10, the energetic particle sources 11a to 11c, and the coating mechanism 12 via the I / F, and controls the operations of these mechanisms.

[0034] Specifically, the control unit 13 controls the rotation speed of each reel and each roller of the transport mechanism 10 (the transport speed of the current collector workpiece 40), the irradiation intensity and irradiation time of the energy particles from the energy particle source 11, the coating thickness of the coating mechanism 12, etc. In addition, when the transport mechanism 10 is provided with a tension control mechanism and a position adjustment mechanism, the control unit 13 also controls the operation of these mechanisms. [Positional Relationship Between Irradiation Area and Current Collector Workpiece 40] FIG. 4 is a diagram showing an example of the positional relationship between the region irradiated with vacuum ultraviolet light from the energetic particle source and the current collector workpiece 40. As shown in FIG. As shown in FIG. 4, when the current collector workpiece 40 is viewed from above, the irradiation areas 110a, 110b, and 110c of the energetic particle sources 11a, 11b, and 11c are each a linear (rectangular) range that includes the entire area of ​​the current collector workpiece 40 in the short side direction.

[0035] 4, the interval L1 between the energetic particle source 11a and the energetic particle source 11b is set as the interval between the point directly below 111a of the energetic particle source 11a and the point directly below 111b of the energetic particle source 11b. Similarly, the interval L2 between the energetic particle source 11b and the energetic particle source 11c is set as the interval between the point directly below 111b of the energetic particle source 11b and the point directly below 111c of the energetic particle source 11c. 4 indicates the conveying direction of current-collector workpiece 40, T1 indicates the radiation pause time in the section between energetic particle sources 11a and 11b, and T2 indicates the radiation pause time in the section between energetic particle sources 11b and 11c.

[0036] In the example of Fig. 4, the transport speed of the current collector workpiece 40 is controlled to a constant speed, and the irradiation pause times T1 and T2 are determined by the lengths of the intervals L1 and L2. That is, the sections of the irradiation pause times T1 and T2 are irradiation pause sections. The irradiation pause times T1 and T2 can also be changed by changing the transport speed. The irradiation pause times are set to a time when the temperature of the current collector workpiece 40 after the rise becomes equal to or lower than a predetermined temperature.

[0037] This predetermined temperature is a temperature at which wrinkles or peeling do not occur on the current collector workpiece 40 even if the active material slurry 50 is continuously applied without cooling by a cooling device after the irradiation process of the energetic particles (vacuum ultraviolet light) by the energetic particle sources 11a to 11c is completed. In addition, the temperature is set to prevent oxidation of the coated surface of the current collector workpiece 40 due to the irradiation of the energetic particles from progressing to the inside of the current collector and causing the surface oxide film to increase more than necessary. The allowable temperature for preventing wrinkles and peeling varies depending on the characteristics of the active material slurry 50 and the material of the current collector workpiece 40. Therefore, it is desirable to set the temperature as low as possible below the vaporization temperature of the solvent added when kneading the active material slurry 50, and for example, in the case of water-soluble solvents, it is desirable to set the temperature below 60[℃]. In addition, in the case of organic solvents (for example, lower alcohols and lower ketones), it is essential to set the temperature below the boiling point of each solvent, and it is desirable to set the temperature below 50[℃]. This is because it is considered that if a vaporization layer occurs at the interface with the vaporized solvent, the solvent will slide there, and the adhesive strength will be extremely weakened. In addition, from the viewpoint of preventing the increase of the oxide film, it is desirable to set the temperature below at least 100[℃] in the case of aluminum.

[0038] The irradiation energy intensity (irradiation energy value) and intervals L1 and L2 of the energetic particle sources 11a to 11c are set so that the intensity can be regarded as substantially non-irradiation at the positions of midpoints Lc1 and Lc2 of the irradiation pause section in Fig. 4. For example, they are set to be 1 / 20 or less of the energy value at the points directly below 111a and 111b. In other words, in a configuration in which multiple energetic particle sources are arranged for irradiation, it is assumed that depending on the lengths of the intervals L1 and L2, light leakage may occur even during the irradiation pause period, and the irradiation energy value may not become zero. The irradiation energy values ​​at the positions of the midpoints Lc1 and Lc2 can be adjusted by adjusting the lengths of the intervals L1 and L2 between the energetic particle sources 11a to 11c. [Electrode manufacturing control process] FIG. 5 is a flowchart showing the electrode manufacturing control process. The processor of the control unit 13 starts a control program stored in a predetermined area of ​​the ROM, and executes an electrode manufacturing control process shown in the flowchart of FIG. 5 in accordance with the program. When the electrode manufacturing control process is executed in the processor, as shown in FIG. 5, first, the process proceeds to step S100. In step S100, setting information that has been input by the user and stored in the ROM in advance is obtained, and then the process proceeds to step S102.

[0039] Here, the setting information includes information such as the irradiation intensity (energy intensity) of the vacuum ultraviolet light from the energetic particle source 11, the irradiation area, the irradiation time and the number of irradiations, and the coating thickness of the active material slurry 50 from the coating mechanism 12. In the first embodiment, the number of irradiations is the same as the number of the energetic particle sources.

[0040] In step S102, based on the setting information acquired in step S100, the transport speed of the transport mechanism 10 for the current collector workpiece 40, the irradiation intensity of the energy particle source 11, the discharge amount of the active material slurry 50 of the coating mechanism 12, etc. are set. Then, the process proceeds to step S104.

[0041] For example, the divided irradiation times are calculated by "irradiation time / number of irradiations (three times in the example of FIG. 3)". Then, the conveying speed is set to a speed that allows irradiation of the divided irradiation times to the same irradiated area based on the divided irradiation times and the irradiated area. In other words, the conveying speed is set to a speed that allows the surface portion of the current collector workpiece 40 that has passed the irradiated area to be irradiated for the divided irradiation times. In addition, the discharge amount of the active material slurry 50 from the coating mechanism 12 is determined to be an appropriate discharge amount based on the coating thickness and the conveying speed. In step S104, the operation control of each mechanism and each particle source is started, and then the process proceeds to step S106. Specifically, the control unit 13 controls the reels and rollers of the transport mechanism 10 so as to transport the current-collector workpiece 40 at a set transport speed.

[0042] Meanwhile, the control unit 13 controls the energetic particle sources 11a to 11c to radiate energy particles at the set irradiation intensity. As a result, the energetic particle sources 11a to 11c radiate vacuum ultraviolet light at the set irradiation intensity. The control unit 13 also controls the energetic particle sources 11a to 11c to continue radiating vacuum ultraviolet light until the irradiation process (surface modification process) on the coating surface of the current-collector workpiece 40 is entirely completed. The timing of starting irradiation may be controlled so that the energetic particle source 11 starts emitting vacuum ultraviolet light in response to detection by a sensor or the like that the current collector workpiece 40 has reached the irradiation area. Furthermore, the control unit 13 sets the amount of active material slurry 50 to be discharged by the application mechanism 12 .

[0043] When the transport mechanism 10 starts to operate under the control of the control unit 13, first, the current collector workpiece 40 is sent from the feed reel 10a to the most upstream guide roller 10b. As a result, the tip of the current collector workpiece 40 is first transported via the multiple guide rollers 10b to the irradiation area (irradiation position of the irradiation region 110a) below the energetic particle source 11a.

[0044] When the tip of the current collector workpiece 40 enters the irradiation area 110a, in the example of Fig. 3, the top surface of the tip (surface to be coated) in the irradiation area 110a is irradiated with vacuum ultraviolet light. During this time, the current collector workpiece 40 is transported at the set transport speed, and the part of the top surface of the tip that first passes through the irradiation area 110a (hereinafter referred to as the "first irradiated part") is irradiated with vacuum ultraviolet light for the divided irradiation time. As a result, the temperature of the first irradiated part becomes higher than before irradiation.

[0045] The section from when the first irradiated portion of the current collector workpiece 40 leaves the irradiation region 110a to when it arrives just before the irradiation region 110b of the energy particle source 11b is an irradiation pause section where the vacuum ultraviolet light is not irradiated. That is, the time during which the first irradiated portion is transported through this irradiation pause section is the irradiation pause time T1, and during the irradiation pause time T1, the first irradiated portion is cooled.

[0046] Subsequently, when the first irradiated portion passes the irradiation position of the irradiation region 110b below the energetic particle source 11b, the first irradiated portion is in a state where it has been irradiated twice with the vacuum ultraviolet light in the divided irradiation time, and the temperature of the first irradiated portion is thus increased from that before the second irradiation.

[0047] The section from when the first irradiated portion leaves the irradiation region 110b to when it reaches just before the irradiation region 110c of the energetic particle source 11c is a second irradiation pause section in which the vacuum ultraviolet light is not irradiated. That is, the time during which the first irradiated portion is transported through this irradiation pause section is an irradiation pause time T2, and during the irradiation pause time T2, the first irradiated portion is cooled.

[0048] The length of section L2 is set so that the irradiation pause time T2 is longer than the irradiation pause time T1, and in the second irradiation pause section, the first irradiated portion is cooled for a time longer than the irradiation pause time T1. This is because the temperature after the first irradiation and after cooling during the irradiation pause time T1 is higher than the initial temperature of the first irradiated portion before the first irradiation, and the temperature of the current collector workpiece 40 is higher after the second irradiation than after the first irradiation.

[0049] Next, when the first irradiated portion passes through the irradiation region 110c below the energy particle source 11c, the first irradiated portion is in a state where it has been irradiated with vacuum ultraviolet light three times in the divided irradiation time. That is, the first irradiated portion is in a state equivalent to when it is continuously irradiated with vacuum ultraviolet light for the set irradiation time. This completes the surface modification process of the first irradiated portion, and the first irradiated portion is made hydrophilic (has wettability). Thereafter, the section until the first irradiated portion reaches the coating area of ​​the coating mechanism 12 also becomes an irradiation pause section, and the first irradiated portion whose temperature has increased due to the third irradiation is cooled. When a sensor (not shown) detects that the first irradiated portion has reached the application area, coating mechanism 12 discharges a set discharge amount of active material slurry 50 onto the first irradiated portion moving at a set transport speed, thereby coating active material slurry 50 onto the first irradiated portion. The series of irradiation, cooling and coating operations described above are sequentially performed on other portions subsequent to the first irradiated portion on the upper surface of the current-collector workpiece 40. In addition, the portion of the current-collector workpiece 40 after being coated with the active material slurry 50 is sequentially taken up by the take-up reel 10c.

[0050] In step S106, it is determined whether the entire current collector workpiece 40 has been wound around the take-up reel 10c, thereby determining whether the process is complete. If it is determined that the process is complete (Yes), the process proceeds to step S108, and if it is determined that the process is not complete (No), the determination process is repeated until the process is complete. When the process proceeds to step S108, the operations of the mechanisms and particle sources of the electrode manufacturing apparatus 1 are stopped, and the series of processes is terminated. [Advantages of the first embodiment]

[0051] In the first embodiment, the same irradiated region of the current collector workpiece 40 of the negative electrode current collector 31a or the positive electrode current collector 33a constituting the electrode is irradiated with energy particles for a predetermined irradiation time (irradiation time required for hydrophilization) in multiple rounds. In addition, an irradiation pause time is provided between each irradiation and the next irradiation in the multiple irradiations of the energy particles.

[0052] As a result, during the irradiation pause time between each irradiation and the next irradiation in the multiple irradiations, the irradiation of the energy particles to the same irradiated area of ​​the current collector workpiece 40 is paused, so that the same irradiated area can be cooled during that time. As a result, the temperature rise of the current collector workpiece 40 due to the irradiation process can be suppressed compared to the case where the same irradiated area is continuously irradiated with energy particles for a predetermined irradiation time. Therefore, the increase in the resistance of the surface oxide film due to the increase in the film thickness of the surface oxide film caused by the temperature rise of the current collector workpiece 40 can be reduced, and the performance deterioration of the secondary battery can be reduced. In addition, when the active material slurry 50 is applied continuously after the irradiation process, a sudden temperature drop due to the application of the active material slurry 50 can be prevented, and the occurrence of shrinkage of the current collector workpiece 40 can be reduced. As a result, it is possible to prevent or reduce the occurrence of wrinkles or partial peeling of the applied active material slurry 50, so that the increase in the interface resistance can be reduced.

[0053] In addition, since the predetermined irradiation time is set to the irradiation time required for hydrophilizing the coating surface of the current collector workpiece 40, the coating surface of the current collector workpiece 40 can be hydrophilized. This makes it possible to impart wettability to the coating surface, and by applying the active material slurry 50 to the coating surface after the wettability has been imparted, it is possible to improve adhesion with the active material slurry 50 and reduce interface resistance. In addition, the conveying mechanism 10 can be shared, thereby reducing equipment costs.

[0054] In the first embodiment, the radiation pause times T1 and T2 are set so that the temperature of the current collector workpiece 40 after it has been raised by the radiation of the energy particles (vacuum ultraviolet photons) is equal to or lower than a predetermined temperature. This predetermined temperature is set to a temperature that prevents or reduces the shrinkage of the current collector workpiece 40 and the increase in the surface oxide film. This makes it possible to more reliably prevent or reduce the shrinkage of the current collector workpiece 40 and the increase in the surface oxide film.

[0055] In the first embodiment, in the multiple irradiation of the same irradiated region of the current-collector workpiece 40 with the energetic particles, the later the irradiation pause time is set to a longer time. That is, the irradiation pause time T2 is set to a time longer than the irradiation pause time T1. Since the temperature of the current collector workpiece 40 becomes higher after the second irradiation than after the first irradiation, the temperature of the current collector workpiece 40 after multiple irradiations can be more reliably lowered to a predetermined temperature or lower by lengthening the rest period of the subsequent irradiations accordingly.

[0056] In the first embodiment, the energetic particle sources 11a to 11c are arranged along the longitudinal direction of the current collector workpiece 40 with an interval L1 between the energetic particle sources 11a and 11b. In addition, the energetic particle sources 11b and 11c are arranged with an interval L2 longer than the interval L1. Furthermore, the transport speed of the transport mechanism 10 is controlled to a constant speed, and the irradiation pause times T1 and T2 are set to different lengths of time depending on the lengths of the intervals L1 and L2. With this configuration, the desired irradiation pause time can be set while keeping the conveying speed constant, making it easier to control the irradiation time and reducing the occurrence of uneven application of the active material slurry 50. [Example of the first embodiment] Next, an example of the first embodiment will be described with reference to the drawings.

[0057] Fig. 6 is a diagram showing a temperature change of a current-collector workpiece when the vacuum ultraviolet light irradiation for the irradiation time required for surface modification is performed continuously, and Fig. 7 is a diagram showing a temperature change of a current-collector workpiece when the vacuum ultraviolet light irradiation for the irradiation time required for surface modification is performed by the divided irradiation method according to the first embodiment.

[0058] The current collector workpiece used to measure the temperature changes in Figures 6 and 7 was made of aluminum foil, and the irradiation dose required for surface modification was 1000 [mJ / cm 2 The illuminance (irradiation energy intensity) of the vacuum ultraviolet light from the energy particle source (vacuum ultraviolet light source) used in this embodiment is 170 [mW / cm 2 ] and the irradiation time required for surface modification is 6 seconds or more. In this example, for comparison, 170 [mW / cm 2 The temperature change when the current collector workpiece was irradiated with vacuum ultraviolet light of each of the following values ​​was measured.

[0059] As shown by the dashed line in Fig. 6, the power was continuously applied for 6 seconds at 170 [mW / cm 2 When the same irradiated area of ​​the current collector workpiece was irradiated with vacuum ultraviolet light of 10 ... Next, the required irradiation time (6 seconds) was divided into three, and irradiation was performed in three separate sessions of 2 seconds each. The temperature change of the current collector workpiece was measured when a 4-second irradiation pause was set after the first irradiation and a 6-second irradiation pause was set after the second irradiation. As shown by the solid line in Figure 7, the temperature after the third irradiation of the current collector workpiece is approximately 43°C, which is approximately 32°C lower than the approximately 75°C achieved when the workpiece is irradiated continuously for 6 seconds without dividing the temperature. Each irradiation pause time may be set to the same time, but instead of setting them to the same time as in this embodiment, the degree of cooling can be strengthened by making the pause times longer toward the end.

[0060] In this embodiment, the thickness of the surface oxide film (passivation film) was measured before and after the aluminum foil current collector workpiece was irradiated with vacuum ultraviolet light. The thickness before the irradiation was 5.4 [nm], and the thickness after three separate irradiations of 2 seconds each with a 4-second rest period after the first and a 6-second rest period after the second was 5.7 [nm]. The thickness after continuous irradiation for 6 seconds was 6.2 [nm].

[0061] That is, when irradiation was performed using the divided irradiation method of the present invention, the temperature reached was 43[℃] and the thickness increase was only slight at 0.3[nm]. On the other hand, when irradiation was performed continuously for 6 seconds, the temperature reached was 75[℃] and the thickness increase was significant at 0.8[nm]. From this, it can be seen that the progression of the surface oxide film in the depth direction can be suppressed by providing an irradiation pause time. In addition, the more power is input to shorten the processing time, the greater the temperature difference tends to be between continuous irradiation and divided irradiation with irradiation rest periods, and the divided irradiation method of the present invention is a method suitable for short-time processing at high power. Second Embodiment Next, a second embodiment of the present invention will be described with reference to the drawings. Figures 8(A), 8(B) and 9 are diagrams showing the second embodiment. The second embodiment differs from the first embodiment in that a single energetic particle source is used in the irradiation process in the irradiation step. Hereinafter, differences from the first embodiment will be described in detail, and descriptions of overlapping parts will be omitted where appropriate. [Configuration of electrode manufacturing device] FIG. 8(A) is a diagram showing a schematic configuration example of an electrode manufacturing apparatus 2 used in the irradiation step and the application step in the second embodiment. As shown in FIG. 8(A), the electrode manufacturing apparatus 2 includes a base 20, a moving stage 21, an energetic particle source 22 that radiates energetic particles, a coating mechanism 23, and a control unit 24. The base 20 supports the moving stage 21 so as to be movable in the direction of the arrow in FIG. 8(A), and includes a moving mechanism (not shown) that moves the moving stage 21 in the direction of the arrow. The moving stage 21 includes a catcher (not shown) for fixing the current collector workpiece 60, and is moved on the base 20 by a moving mechanism in the direction of the arrow in FIG. 8(A). Here, the current collector workpiece 60 is made of the same material as the current collector workpiece 40 of the first embodiment, and is a workpiece that is shorter than the current collector workpiece 40. In other words, the current collector workpiece 60 does not have a length sufficient to be wound around a reel for processing. The energetic particle source 22 is a particle source similar to the energetic particle source 11 of the above-described first embodiment. In the following description, the energetic particle source 22 is an atmospheric pressure plasma radiation source that emits atmospheric pressure plasma particles. The coating mechanism 23 is a device that coats the surface to be coated of the current-collector workpiece 60 after irradiation treatment (after surface modification) with the active material slurry 50, similar to the coating mechanism 12 of the first embodiment.

[0062] The control unit 24 includes a processor, a ROM, a RAM, an I / F, and a bus for connecting them to each other so that data can be exchanged, similar to the control unit 13 of the first embodiment. In addition, the control unit 24 includes a timer for determining the lapse of the divided irradiation time and the irradiation pause time, a first counter for counting the number of irradiations, and a second counter for counting the number of surface modification treatments. The control unit 24 is electrically connected to the moving mechanism of the base 20, the energetic particle source 22, and the coating mechanism 23 via the I / F, and controls the operations of these mechanisms. Specifically, control unit 24 controls the movement of the movement mechanism (movement of current collector workpiece 60), the irradiation intensity of the atmospheric pressure plasma of energetic particle source 22, the irradiation time, the on / off of irradiation, the coating thickness of coating mechanism 23, and the like. [Positional Relationship Between Irradiation Area and Current Collector Workpiece 60] FIG. 8B is a diagram showing an example of the positional relationship between the irradiation area of ​​the energetic particle source 22 and the current collector workpiece 60. As shown in FIG.

[0063] When the current collector workpiece 60 is viewed from above, the irradiation area 220 of the energetic particle source 22 is a linear range including the entire area in the short side direction of the current collector workpiece 60, as shown in the dashed rectangle in Fig. 8(B) . Note that the irradiation area 220 of the atmospheric pressure plasma of the energetic particle source 22 is narrower than the irradiation areas 110a to 110c of the vacuum ultraviolet light of the energetic particle source 11 of the first embodiment.

[0064] The current collector workpiece 60 can be moved in the direction of the arrow in Fig. 8(B) by a moving mechanism. In the second embodiment, the width of the irradiation area 220 in the short side direction is shorter than the length of the current collector workpiece 60. Therefore, in the second embodiment, the surface to be coated of the current collector workpiece 60 is divided into multiple parts based on the width of the irradiation area 220, and the current collector workpiece 60 is moved by the moving mechanism to sequentially perform divided irradiation processing on each divided area. [Electrode manufacturing control process] FIG. 9 is a flowchart showing an electrode manufacturing control process according to the second embodiment. The processor of the control unit 24 starts a control program stored in a predetermined area of ​​the ROM, and executes an electrode manufacturing control process shown in the flowchart of FIG. 9 in accordance with the program. When the electrode manufacturing control process is executed in the processor, as shown in FIG. 9, first, the process proceeds to step S200. In step S200, setting information that has been input by the user and stored in the ROM in advance is obtained, and then the process proceeds to step S202. Here, the setting information includes information such as the irradiation energy intensity of the atmospheric pressure plasma from the energetic particle source 22, the irradiation area, the irradiation time and the number of irradiations, the number of treatments for the surface modification treatment, and the coating thickness of the active material slurry 50 from the coating mechanism 12. Here, the number of times of divided irradiation processing is set based on the irradiation area and the length of the current collector workpiece 60, for example. In step S202, the irradiation intensity of the atmospheric pressure plasma from the energetic particle source 22 and the discharge amount of the active material slurry 50 from the coating mechanism 23 are set based on the setting information acquired in step S200. Then, the process proceeds to step S204. As in the first embodiment, the divided irradiation time is calculated by "irradiation time / number of irradiations." For example, if the irradiation time is 70 seconds and the number of irradiations is 10, the divided irradiation time is 7 seconds. Moreover, the amount of active material slurry 50 discharged by coating mechanism 23 is determined to be an appropriate amount based on the coating thickness and the moving speed of current collector workpiece 60 by the moving mechanism. Moreover, the radiation pause time is set so that the temperature after the increase due to radiation is equal to or lower than a predetermined temperature, similarly to the first embodiment. In step S204, the moving mechanism is controlled to move the current-collector workpiece 60 to an initial position for irradiating the energetic particles. In addition, the timer, the first counter, and the second counter are reset. Then, the process proceeds to step S206. In step S206, the energetic particle source 22 is caused to start irradiating the irradiated area of ​​the current-collector workpiece 60 located at the irradiation position of the irradiation area 220 with atmospheric pressure plasma, and the timer is started to measure the divided irradiation time. Then, the process proceeds to step S208.

[0065] In step S208, it is determined whether or not the divided irradiation time has elapsed based on the timer value, and if it is determined that the divided irradiation time has elapsed (Yes), the process proceeds to step S210. On the other hand, if it is determined that the divided irradiation time has not elapsed (No), the process continues irradiating the atmospheric pressure plasma and repeats the determination process until the divided irradiation time has elapsed. When the process proceeds to step S210, the process stops the irradiation of the atmospheric pressure plasma from the energetic particle source 22. The process also resets the timer, and starts measuring the next irradiation pause time using the timer. Then, the process proceeds to step S212.

[0066] In step S212, it is determined whether the irradiation pause time has elapsed based on the timer value. If it is determined that the irradiation pause time has elapsed (Yes), the timer is reset and the process proceeds to step S214, and if it is determined that the irradiation pause time has not elapsed (No), the determination process is repeated until the irradiation pause time has elapsed.

[0067] When the process proceeds to step S214, it is determined based on the count value of the first counter whether or not irradiation of the set number of times has been completed for the same irradiated area of ​​the current collector workpiece 60. If it is determined that irradiation has been completed (Yes), the first counter is reset and the process proceeds to step S216, and if it is determined that irradiation has not been completed (No), 1 is added to the count value of the first counter and the process proceeds to step S206.

[0068] When the process proceeds to step S216, it is determined whether or not the divided irradiation process for the set number of processes is completed based on the count value of the second counter. If it is determined that the divided irradiation process is completed (Yes), the second counter is reset and the process proceeds to step S218, and if it is determined that the divided irradiation process is not completed (No), 1 is added to the count value of the second counter and the process proceeds to step S222. When the process proceeds to step S218, the movement mechanism is controlled to move the current-collector workpiece 60 to the application position of the application mechanism 23. After that, the process proceeds to step S220. In step S220, the coating mechanism 23 applies the active material slurry 50 to the current-collector workpiece 60 after the surface modification. Specifically, the moving mechanism moves the current collector workpiece 60 at a set speed, and the coating mechanism 23 discharges the active material slurry 50 at a set discharge rate onto the coating surface of the current collector workpiece 60 moving at the set speed.

[0069] On the other hand, if it is determined in step S216 that the divided irradiation processes for the set number of processes have not been completed and the process proceeds to step S222, the movement mechanism is controlled to move the next irradiated area of ​​the current-collector workpiece 60 to the irradiation position of the energetic particle source 22. In addition, the timer is reset, and the process proceeds to step S206. [Advantages of the second embodiment]

[0070] In the second embodiment, the same irradiated region of the collector workpiece 40 of the negative electrode collector 31a or the positive electrode collector 33a constituting the electrode is irradiated with energy particles for a predetermined irradiation time (irradiation time required for hydrophilization) in multiple rounds. In addition, an irradiation pause time is provided between each irradiation and the next irradiation in the multiple irradiations of the energy particles.

[0071] As a result, during the irradiation pause time between each irradiation and the next irradiation in the multiple irradiations, the irradiation of the energy particles to the same irradiated area of ​​the current collector workpiece 60 is paused, so that the same irradiated area can be cooled during that time. As a result, the temperature rise of the current collector workpiece 60 due to the irradiation process can be suppressed compared to the case where the same irradiated area is continuously irradiated with energy particles for a predetermined irradiation time. Therefore, the increase in the resistance of the surface oxide film due to the increase in the film thickness of the surface oxide film caused by the temperature rise of the current collector workpiece 60 can be reduced, and the performance deterioration of the secondary battery can be reduced. In addition, when the active material slurry 50 is applied continuously after the irradiation process, the occurrence of contraction of the current collector workpiece 60 due to the sudden temperature drop caused by the application of the active material slurry 50 can be reduced. As a result, the occurrence of wrinkles or partial peeling of the applied active material slurry 50 can be prevented or reduced, so that the increase in the interface resistance can be reduced.

[0072] In addition, since the predetermined irradiation time is set to the irradiation time required for hydrophilizing the coated surface of the current-collector workpiece 60, it is possible to hydrophilize the coated surface of the current-collector workpiece 60. This makes it possible to impart wettability to the coated surface, and by applying the active material slurry 50 to the coated surface after the wettability has been imparted, it is possible to improve adhesion with the active material slurry 50 and reduce interface resistance.

[0073] In the second embodiment, the irradiation pause time is set so that the temperature of the current collector workpiece 60 after it has been raised by irradiation with the energetic particles (atmospheric pressure plasma particles) is equal to or lower than a predetermined temperature. This predetermined temperature is set to a temperature that prevents or reduces the shrinkage of the current collector workpiece 60 and the increase in the surface oxide film. This makes it possible to more reliably prevent or reduce the shrinkage of the current collector workpiece 60 and the increase in the surface oxide film. In the second embodiment, the irradiation pause time is set to two different lengths and alternately repeats these two lengths, which makes it easier to control the temperature to a predetermined temperature or lower and makes the temperature rise more gradual than when the same length of irradiation pause time is set between each irradiation and the next irradiation. [Example of the second embodiment] Next, an example of the second embodiment will be described with reference to the drawings. Fig. 10 is a diagram showing the temperature change of the current collector workpiece when the atmospheric pressure plasma particles are continuously irradiated for the irradiation time required for surface modification and when the divided irradiation method of the present invention is used. In Fig. 10, the horizontal axis is time (seconds) and the vertical axis is the temperature of the current collector workpiece (°C).

[0074] The current collector workpiece used in the experiment was made of aluminum foil, and the irradiation dose required for surface modification was 1000 [mJ / cm 2 The irradiation energy intensity of the atmospheric pressure plasma particles from the energetic particle source (atmospheric pressure plasma radiation source) used in this example is about 14.5 [mW / cm 2 ] and the irradiation time required for surface modification is 70 seconds or more. Moreover, similarly to the electrode manufacturing apparatus 2 of the second embodiment, the temperature change was measured when a surface treatment was performed using a single energy particle source (plasma radiation source). In this embodiment, as shown by the dashed line in FIG. 10, for comparison with the divided irradiation method, the irradiation was performed continuously for about 300 seconds at about 14.5 [mW / cm 2 The temperature change was measured when the atmospheric pressure plasma particles of [ ] were irradiated to the same irradiated area of ​​the current collector workpiece. As shown by the dashed line in Figure 10, the measurement results at the time position where atmospheric pressure plasma particles were continuously irradiated for 70 seconds show that the temperature of the current collector workpiece reached approximately 90°C. On the other hand, as shown by the solid line in Figure 10, the radiation intensity of the same irradiated area of ​​the current collector workpiece was approximately 14.5 [mW / cm 2 The temperature change was measured when the sample was irradiated with atmospheric pressure plasma particles of [1000 μm] for 70 seconds using the divided irradiation method of the present invention.

[0075] Specifically, 70 seconds was divided into 10 parts, and irradiation was performed in 10 parts with each part being 7 seconds long. The temperature change was measured after a 16 second rest period after each odd-numbered irradiation, and after the 2nd, 4th, 6th, and 8th even-numbered irradiations, with a 12 second rest period after each. As shown by the solid line in Figure 10, the temperature after the 10th irradiation of the same irradiated area of ​​the current collector work reaches approximately 70°C, which is approximately 20°C lower than the approximately 90°C achieved when irradiating continuously for 70 seconds without dividing the temperature.

[0076] Also, as shown by the solid line in Figure 10, it can be seen that by alternately inserting two types of irradiation rest periods of different lengths, the difference between the minimum temperature (about 58[°C]) and maximum temperature (about 70[°C]) of the current collector work after it has risen can be suppressed to about 12[°C]. In other words, it can be seen that by alternately inserting irradiation rest periods of different lengths, it is possible to achieve a relatively gradual temperature rise without any sudden temperature rises along the way. Third embodiment Next, a third embodiment of the present invention will be described with reference to the drawings. Figures 11 and 12 are diagrams showing the third embodiment. The third embodiment differs from the first and second embodiments in that the range of the compounding ratio of the conductive assistant in the active material slurry (hereinafter simply referred to as "slurry") is set to a specific range. Hereinafter, differences from the first and second embodiments will be described in detail, and descriptions of overlapping parts will be omitted where appropriate.

[0077] The inventors have found that the effect of reducing the interface resistance by the hydrophilic treatment (surface modification treatment) on the battery performance is remarkable when the electrical resistance of the slurry itself is relatively high. That is, when the compounding ratio of the conductive assistant is relatively low and the density of the slurry is relatively low. In such a state, the electrical resistance of the slurry itself becomes large, and when the resistance of the interface is added to this, it exceeds the allowable resistance of the entire electrode for maintaining the performance of the secondary battery. The reason why the electrical resistance of the slurry increases when the density of the slurry is relatively low is presumably because the contact between the conductive assistants, between the conductive assistant and the active material, or between the conductive assistant and the current collector becomes poor, causing the electrical resistance of the slurry to increase.

[0078] In addition, when the slurry is compressed by compression treatment, the density increases, the slurry becomes dense, the contact of the conductive assistant becomes dense, and the resistance value of the slurry decreases. However, excessive compression makes it difficult for lithium ions, etc. to move in the slurry film, and the battery performance decreases, so the density cannot be increased unnecessarily. It is required to keep the density below a level at which the movement of lithium ions, etc. can be sufficiently ensured.

[0079] If the resistance of the slurry is small, the interface resistance will not exceed the allowable value even if it is large. However, in order to increase the capacity and charge / discharge capacity of the battery, it is necessary to reduce the proportion of materials other than the active material as much as possible, so it is desirable to reduce the conductive additive, and attempts to reduce the interface resistance value meet this requirement. In addition, even if the density of the slurry cannot be increased due to the above-mentioned reasons and the resistance of the slurry becomes large, attempts to reduce the interface resistance value are effective solutions to improve battery performance. In other words, by realizing the surface modification treatment of the current collector by vacuum ultraviolet light or atmospheric pressure plasma irradiation treatment in a way that minimizes the increase in the surface oxide film of the current collector, it is possible to improve not only the deterioration characteristics but also the performance of the capacity and charge / discharge characteristics, which are the basic characteristics of the entire secondary battery.

[0080] Therefore, in the third embodiment, when the sum of the mixing ratio V [%] of the active material 35, the mixing ratio X [%] of the conductive assistant 36, and the mixing ratio Y [%] of the binder 37 in the active material slurry 50 is 100 [%], the range of the mixing ratio X [%] of the conductive assistant 36 is set to 0 < X ≦ 5. Hereinafter, the active material slurry 50 is simply referred to as "slurry 50".

[0081] FIG. 11 is a diagram showing the rated capacity measured when a secondary battery cell is assembled with a current collector coated with the slurry 50 having the mixing ratio X of the conductive assistant 36 of 2 [%] and charged and discharged repeatedly a plurality of times. FIG. 12 is a diagram showing the rated capacity measured when a secondary battery cell is assembled with a current collector coated with the slurry 50 having the mixing ratio X of the conductive assistant 36 of 5 [%] and charged and discharged repeatedly a plurality of times.

[0082] In FIGS. 11 and 12, "untreated" shows the measurement results when the irradiation treatment by the divided irradiation method of the present invention is untreated. In addition, "AP" shows the measurement results when the irradiation treatment by the divided irradiation method of the present invention is performed with atmospheric pressure plasma, and "VUV" shows the measurement results when the irradiation treatment by the divided irradiation method of the present invention is performed with vacuum ultraviolet light. In FIGS. 11 and 12, the charge and discharge rate was repeated 8 times in the order of 0.2 [C (Capacity)] (2 times) → 1 [C] (2 times) → 2 [C] (2 times) → 0.2 [C] (2 times), and the rated capacity at the end of each charge and discharge was measured.

[0083] Here, the charge and discharge rate (C (battery nominal capacity / Capacity) rate) is the speed of charging and discharging of the secondary battery, and can be obtained by the amount of electricity [C] = capacity [Ah] / 3600 seconds [s]. Also, the "2 times" in the parentheses indicates a total of 2 times when a full charge is performed once at each charge and discharge rate and a complete discharge after charging is performed once.

[0084] Also, the above 1[C] represents the current value when the battery goes from fully charged to fully discharged in 1 hour. In other words, the higher this number, the larger the current that can be output. Similarly, the above 2[C] represents the current value when the battery goes from fully charged to fully discharged in 30 minutes, and the above 0.2[C] represents the current value when the battery goes from fully charged to fully discharged in 5 hours. For example, if the capacity of a secondary battery is 20 [Ah], the current value at 1 [C] is 20 [A], the current value at 2 [C] is 40 [A], and the current value at 0.2 [C] is 4 [A].

[0085] 11 and 12, aluminum foil was used for the positive electrode current collector 33a, and lithium nickel-cobalt-manganese oxide NCM523 was used for the active material 35. Furthermore, Ketjen black (KB), which is a highly conductive carbon black, was used for the conductive additive 36, and polyvinylidene fluoride (PVDF) was used for the binder 37. Graphite was used for the negative electrode current collector 31a, 1M-LiPF6 / EC was used for the electrolyte 34, and polyethylene was used for the separator 32. In the measurement of FIG. 11, a slurry 50 was used in which the compounding ratio X [%] of the conductive additive was 2 [%] when the sum of the compounding ratio V [%] of the active material 35, the compounding ratio X [%] of the conductive additive 36, and the compounding ratio Y [%] of the binder 37 was 100 [%].

[0086] Here, if the weight of active material 35 is W1, the weight of conductive additive 36 is W2, and the weight of binder 37 is W3, the total compounding ratio can be calculated as "V+X+Y={W1 / (W1+W2+W3)+W2 / (W1+W2+W3)+W3 / (W1+W2+W3)}×100". 12, a slurry 50 was used in which the compounding ratio X of the conductive additive 36 was set to 5[%] instead of 2[%] in FIG. 11. The amount of the active material 35 was reduced to compensate for the increase in the conductive additive 36. As shown in Figure 11, when the compounding ratio of conductive additive 36 is 2%, comparing the measurement results of untreated (△), AP (◯), and VUV (□) in the figure, it can be seen that the rated capacity is significantly improved by split irradiation treatment for both VUV and AP compared to the untreated case. On the one hand, as shown in Fig. 12, when the mixing ratio of the conductive additive is 5%, an improvement in the rated capacity can be seen for both VUV and AP compared to the untreated case, but the difference is slight. From this, it was understood that when the mixing ratio of the conductive additive is 5% or less, the effect of the surface modification treatment by the divided irradiation treatment of the present invention appears, and the smaller the value, the more remarkable the effect of the surface modification treatment appears. 〔Effect of the third embodiment〕

[0087] In the third embodiment, when the sum of the mixing ratio V[%] of the active material 35, the mixing ratio X[%] of the conductive additive 36, and the mixing ratio Y[%] of the binder 37 constituting the active material slurry 50 is 100%, the range of the mixing ratio X[%] of the conductive additive 36 is set to the range of 0 < X ≦ 5. Thereby, when the surface modification treatment is performed by the divided irradiation method of the present invention, the effect of improving the capacity and charge-discharge ability of the battery can be further enhanced as compared with the case where it is outside the above range. 〔Modification example〕

[0088] In the above first embodiment, the irradiation pause time is set according to the lengths of the arrangement intervals L1 and L2 of the energy particle sources 11a to 11c, but the configuration is not limited to this. For example, a configuration may be adopted in which a bypass circuit for avoiding the irradiation of energy particles is formed in the transport path. Fig. 13 is a diagram showing a schematic configuration of an electrode manufacturing apparatus 1A according to a modification example. As shown in Fig. 13, the electrode manufacturing apparatus 1A has a configuration in which a transport mechanism 10A is provided instead of the transport mechanism 10 in the electrode manufacturing apparatus 1 of the above first embodiment. The transport mechanism 10A includes a feed reel 10a, a plurality of guide rollers 10b, a take-up reel 10c, and a plurality of bypass rollers 10d. The plurality of bypass rollers 10d form a bypass circuit 101 that forms an irradiation pause section of the irradiation pause time T1 between the energy particle sources 11a and 11b, and a bypass circuit 102 that forms an irradiation pause section of the irradiation pause time T2 between the energy particle sources 11b and 11c.

[0089] The detours 101 and 102 each form a detour that detours the current collector workpiece 40 toward the lower side of the regular transport path in a substantially U-shaped manner in a side view, and the length of the detour (the length of the workpiece to be detoured) corresponds to the intervals L1 and L2 in the first embodiment. In the example of FIG. 13, the lengths of the detours 101 and 102 are configured to be the same, so that the irradiation pause time is the same for both, but this is not limited to this configuration, and the lengths of the detours may be configured to be different lengths instead of being equal. In this way, by forming the detour, the irradiation pause time can be adjusted only by the length of the detour, so that it is possible to change only the irradiation pause time without changing the interval between the energy particle sources and the transport speed of the current collector workpiece 40.

[0090] In the second embodiment, the current collector workpiece 60 is moved by the moving mechanism, but the present invention is not limited to this configuration, and for example, the current collector workpiece 60 may be fixed and the energetic particle source 22 and the coating mechanism 23 may be moved. Alternatively, the current collector workpiece 60, the energetic particle source 22, and the coating mechanism 23 may both be movable, and these may be moved relative to each other.

[0091] In the second embodiment and its modified example, the irradiation process is performed for a plurality of irradiated regions of the current collector workpiece 60 by a plurality of divided irradiation times with an irradiation pause time interposed between each irradiated region, but the present invention is not limited to this configuration. For example, after a certain irradiated region is irradiated for a divided irradiation time, another irradiated region may be irradiated for a divided irradiation time until the irradiation pause time has elapsed. This allows irradiation processes to be performed on a plurality of irradiated regions while waiting for the irradiation pause time to elapse, thereby improving the efficiency of the divided irradiation process.

[0092] In addition, although specific embodiments and modifications thereof have been described above, the embodiments and modifications thereof are merely illustrative and are not intended to limit the scope of the present invention. The apparatus and method described herein can be embodied in forms other than those described above. Furthermore, the above-described embodiments and modifications thereof can be omitted, substituted, and modified as appropriate without departing from the scope of the present invention. Such omitted, substituted, and modified forms are included in the scope of the claims and their equivalents, and belong to the technical scope of the present invention. [Explanation of symbols]

[0093] 1,1A,2...electrode manufacturing apparatus, 10,10A...transport mechanism, 10a...feed reel, 10b...guide roller, 10c...take-up reel, 10d...bypass roller, 11,11a to 11c,22...energy particle source, 12,23...coating mechanism, 13,24...control unit, 14...thermostatic bath, 30...lithium ion secondary battery, 31...negative electrode, 31a...negative electrode collector, 31b...negative electrode active material layer, 32...separator, 33...positive electrode, 33a...positive electrode collector, 33b...positive electrode active material layer, 34...electrolyte, 35...active material, 35c...cracked active material, 36...conductive assistant, 37...binder, 38...void, 40,60...current collector work, 50...active material slurry, 110a to 110c,220...irradiation area

Claims

1. An electrode manufacturing method for manufacturing an electrode of a secondary battery, comprising the steps of: an irradiation step of irradiating at least one surface of a workpiece of a current collector constituting the electrode with energetic particles to perform irradiation treatment; A coating process of coating a slurry containing an active material onto the surface of the workpiece that has been irradiated with the energy particles in the irradiation process, In the irradiation step, An electrode manufacturing method characterized in that the energy particles are irradiated to the same irradiated area of ​​the workpiece multiple times for a predetermined irradiation time, and an irradiation pause time is provided between each of the multiple irradiations of the energy particles to pause the irradiation of the energy particles to the same irradiated area.

2. In claim 1, In the irradiation step, a rest time for irradiation of the workpiece is controlled so that the temperature of the workpiece after the temperature rise due to the irradiation of the energetic particles is kept below a predetermined temperature.

3. In claim 1, In the irradiation step, A method for manufacturing an electrode, comprising the steps of: setting a plurality of types of irradiation pause times having different time lengths.

4. In claim 3, The electrode manufacturing method according to the present invention is characterized in that, in irradiating the same irradiated region with the energetic particles a plurality of times, a longer irradiation pause time is set for each subsequent irradiation.

5. In claim 1, The electrode manufacturing method according to the present invention, wherein the energetic particles are photons having a wavelength of 200 nm or less, or plasma particles.

6. In claim 1, the slurry contains the active material, a conductive additive, and a binder, and when the sum of the compounding ratios of the active material, the conductive additive, and the binder is 100[%], a compounding ratio X [%] of the conductive additive is in the range of 0<X≦5.

7. An electrode manufacturing apparatus for manufacturing an electrode of a secondary battery, comprising: an energetic particle source that emits energetic particles; a moving mechanism for moving at least one of a current collector workpiece constituting the electrode and the energetic particle source; a control unit for controlling the energetic particle source and the moving mechanism, The control unit is Controlling the moving mechanism so that the irradiation area of ​​the energy particle source moves along or relatively moves the surface of the workpiece; An electrode manufacturing apparatus characterized in that the energy particle source is controlled to irradiate the energy particles to the same irradiated area of ​​the workpiece multiple times for a predetermined irradiation time, and to provide an irradiation pause time between each of the multiple irradiations of the energy particles and the next irradiation of the same irradiated area, during which the irradiation of the energy particles to the same irradiated area is paused.

8. An electrode manufacturing apparatus for manufacturing an electrode of a secondary battery, comprising: a plurality of energetic particle sources for emitting energetic particles; a conveying mechanism for conveying a current collector workpiece constituting the electrode; a control unit for controlling the plurality of energetic particle sources and the transport mechanism, The plurality of energetic particle sources are arranged at predetermined intervals along a longitudinal direction of the workpiece, the transport mechanism is configured to transport the workpiece to the irradiation positions of the energetic particles of each of the energetic particle sources in sequence; The control unit is an electrode manufacturing apparatus that controls the transport mechanism to a transport speed that enables the energetic particles to be irradiated to the same irradiated area of ​​the workpiece during a divided irradiation time obtained by dividing a predetermined irradiation time required for processing into a number equal to the number of energetic particle sources at each irradiation position, and controls the transport mechanism to a transport speed that enables the creation of an irradiation pause time during which the irradiation to the same irradiated area is paused in the predetermined interval section.

9. In claim 8, The electrode manufacturing apparatus is characterized in that the predetermined interval is configured to have a plurality of intervals of different lengths.

10. In claim 9, An electrode manufacturing apparatus characterized in that the multiple types of spacing are configured so that the spacing between the energetic particle sources arranged downstream in the transport direction is longer than the spacing between the energetic particle sources arranged upstream.

11. In claim 7 or 8, 11. An electrode manufacturing apparatus, wherein the energetic particle source is an ultraviolet radiation source that radiates photons having a wavelength of 200 nm or less, or a plasma radiation source that radiates atmospheric pressure plasma particles.

12. In claim 7 or 8, an electrode manufacturing apparatus comprising a coating mechanism for coating a slurry containing an active material on the surface of the workpiece after the energy particles have been irradiated thereon;

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