JP4904782B2 - Electrode plate manufacturing method and manufacturing apparatus thereof - Google Patents

Description

  The present invention relates to a method for producing an electrode plate for continuously transporting an electrode plate used for a secondary battery into a drying furnace, and producing an electrode plate that is not oxidized while drying the entire electrode plate uniformly and efficiently, and The present invention relates to the manufacturing apparatus.

  In recent years, portable and cordless electronic devices such as AV devices, personal computers, and portable communication devices have been rapidly promoted. As drive power sources for these electronic devices and other power sources, load characteristics with high energy density are provided. Therefore, there is a demand for an excellent sealed battery. In particular, lithium ion secondary batteries having many features such as high energy density and voltage, and long shelf life are in the spotlight.

  As described above, as a lithium ion secondary battery used for high-current discharge applications, a positive electrode plate and a negative electrode plate, which are electrode plates formed by drying a solid portion where no active material is applied at least in the width direction, are applied. Are wound in a spiral shape so that each upper end side or lower end side protrudes from the upper and lower sides of the electrode plate group via a separator, and a plurality of current collectors are provided at the tip portions of the positive and negative electrode plates protruding from the upper and lower sides. A structure with improved current collecting performance from the electrode plate group by welding with the electrode plate and a solid plate portion of the electrode plate core material to which no active material is applied in the width direction of the positive electrode plate and the negative electrode plate. In addition, there is a structure in which a current collector is welded to the plain portion, and then the current is collected via a current collector protruding from an electrode plate group wound spirally through a separator.

  As a method for applying these active materials, the active material is formed by applying a coating method such as a comma coater or a die coater, and the coated electrode plate is formed by using an active material or a binder as a solvent (water). The organic solvent is kneaded and dispersed into a paste, and the solvent needs to be heated and dried.

In order to dry the paste-like positive electrode mixture or negative electrode mixture (hereinafter referred to as “mixture”) applied to the electrode plate core material, the electrode plate core material is heated to directly heat the paste compound mixture directly. There is a high-frequency heating method using an electromagnetic induction coil as a method to do this, and the electromagnetic induction coil used in the high-frequency heating device has a high magnetic flux density in the outer peripheral part, and a part of the magnetic flux concentrates on the end of the electrode plate core material. As a result, the electrode plate core material is oxidized or burnt, and a stable quality electrode plate cannot be obtained. As a countermeasure, there has been proposed a method of coping with winding the electromagnetic induction coil in a direction gradually separating from the electrode plate from the central portion to the outer peripheral portion of the electromagnetic induction coil in order to generate a uniform magnetic flux density (for example, , See Patent Document 1).
Japanese Patent Laid-Open No. 9-245947

  However, in the above-mentioned patent document, which is the prior art, a magnetic field having a uniform magnetic flux density can be generated on the entire surface of the electrode plate core material, but a paste-like mixture is applied to the electrode plate core material. In the electrode plate that is used, the thickness of the electrode plate is uneven, the width, and the difference in distance from the electromagnetic induction coil due to changes in the travel position. An electrode plate of uniform quality cannot be obtained.

  Considering the unevenness of heat generation, if the electrode plate is heated too much, the uncoated region is oxidized, and if an oxidized film is formed on the oxidized uncoated region, the current collector is placed on the uncoated region of the electrode plate. When welding is performed, poor welding occurs and high current collection efficiency cannot be obtained.

  In addition, in order to dry the electrode plate without forming an oxide film, the amount of current flowing to the electromagnetic induction coil must be regulated, and the electromagnetic induction coil has a magnetic field in which the magnetic flux density at the outer peripheral portion is higher than that at the center. Due to the edge effect of generating the electrode plate, there is a problem that the electrode plate is not uniformly dried due to extremely uneven temperature in the vicinity of the outer peripheral portion and the central portion of a thin material such as an electrode plate core.

  Furthermore, the heating of the electrode plate core material using only the high-frequency heating device also causes a problem that the productivity is poor due to the limitation in the speed of evaporating the solvent of the applied paste-like mixture.

  The present invention has been made in view of the above-described conventional problems, and there is no unevenness of extreme temperature even though the plain portion of the electrode plate does not oxidize. It aims at providing the manufacturing method of a board.

To achieve the above object, the present invention provides a positive electrode mixture or a negative electrode mixture made of a band-shaped metal in a drying furnace provided with an electromagnetic induction coil to which current is transmitted from a high-frequency generator and a hot air generator . The electromagnetic induction coil installed in the drying furnace and the electrode plate passing through the drying furnace, having a conveying means for continuously carrying in an electrode plate coated partially or entirely on an electrode plate core The ferrite core is installed at a location located at both ends of the electrode plate.

In the present invention , a positive electrode mixture or a negative electrode mixture is partially placed on a strip-shaped metal electrode plate core material in a drying furnace equipped with an electromagnetic induction coil to which current is transmitted from a high-frequency generator and a hot air generator. or a conveying means for continuously transferring the entirely coated electrode plates, the ferrite cores between the electrode plates to pass the electromagnetic induction coils installed in the drying oven the drying oven By installing at locations located at both ends of the electrode plate, the magnetic flux generated from the electromagnetic induction coil can be concentrated on the ferrite core, and the rapid temperature rise only at the end of the electrode plate can be controlled. The electrode plate can be dried.

According to a first aspect of the present invention , a positive electrode mixture or a negative electrode mixture is formed in a strip-shaped metal plate core in a drying furnace provided with an electromagnetic induction coil to which current is transmitted from a high-frequency generator and a hot air generator. a conveying means for continuously transferring the partially or entirely coated electrode plates on the timber, between the electrode plates to pass the electromagnetic induction coils installed in the drying oven the drying oven In addition, the magnetic flux generated from the electromagnetic induction coil is concentrated on the ferrite core by controlling the sudden temperature rise only at the end of the electrode plate. Thus, it becomes possible to dry the electrode plate uniformly.

According to the second aspect of the present invention, since the width of the electromagnetic induction coil is narrower than the width direction of the electrode plate, it is possible to prevent a rapid temperature rise only at both ends of the electrode plate, and to meet the specifications of the electrode plate. Since it is not necessary to prepare a combined electromagnetic induction coil, and it is possible to easily cope with various sizes of electrode plates, it is possible to provide a manufacturing apparatus that is excellent in maintainability and response time efficiency at the time of product type switching.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of an electrode plate manufacturing apparatus according to the present invention. The electrode plate core material 1 is continuously unwound from the unwinding portion 2, and a paste-like mixture 4 made of an active material is discharged from the coating die nozzle 3 onto the electrode plate core material 1 and applied at the coating portion. This is a manufacturing method of forming and carrying into the drying furnace 5 using a carrying-in means.

  Here, in the positive electrode mixture using the composite lithium oxide as the active material in the paste-like mixture 4 made of the active material, 100 parts by weight of lithium cobaltate as an example of the active material, and 100 parts by weight of the active material Then, 3 parts by weight of acetylene black as a conductive agent and 3 parts by weight of polyvinylidene fluoride as a binder are stirred together with an appropriate amount of N-methyl-2-pyrrolidone using a universal mixer having a stirring blade that rotates and revolves. The mixture is then kneaded to form a paste-like positive electrode mixture.

  Further, in the negative electrode mixture that is an active material capable of holding lithium, 100 parts by weight of graphite as an example of the active material, and a styrene-butadiene copolymer rubber particle that is a binder with respect to 100 parts by weight of the active material 2.5 parts by weight of the dispersion and 1 part by weight of carboxymethyl cellulose as a thickener are added, the same weight is added to the solid content using water as a solvent, and the mixture is stirred and kneaded using a universal mixer to obtain a paste-like negative electrode A mixture is formed.

  The paste-like positive electrode mixture or negative electrode mixture is discharged from the coating portion formed by the coating die nozzle 3 and applied to the electrode plate core material 1. The electrode plate core material 1 to which the positive electrode mixture is applied is made of aluminum or aluminum alloy foil or lath processed or etched 10 μm to 60 μm thick, and the negative electrode mixture is made of 10 μm thick copper foil. It is applied to the core material 1. Also, as a coating pattern, at least one end portion in the width direction of the electrode plate core material 1 is provided with a plain portion to which the mixture 4 is not applied and is applied in the width direction of the electrode plate 14 or the electrode plate core material 1 coated on the entire surface. There is an intermittently coated electrode plate 14 that partially applies the agent 4.

The electrode plate 14 is carried into the drying furnace 5 using a conveying means. In the present invention, tension is generated between the entrance roller 13 and the exit roller 16 using the unwinding unit 2 and the winding unit 8, and the electrode plate 14 is carried in. In addition, in a carrying-in means, a mesh-like conveyor may be sufficient and the carrying-in means which does not contact the electrode plate 14 like the carrying-in means of this invention is preferable.

  The drying furnace 5 is composed of three chambers. In the first chamber, two sets of electromagnetic induction coils 6 are arranged at a position keeping a predetermined distance from the electrode plate 14, and hot air discharged at a predetermined temperature is sent to each chamber. Yes.

  Next, a current is transmitted from the high frequency generator 7 installed outside the drying furnace 5 to the electromagnetic induction coil 6 disposed in the drying furnace 5 to cause the electrode plate core 1 to generate heat, and the mixture 4 is kept at a constant temperature. It passes through the maintained drying furnace 5, is dried, and is taken up together with the electrode plate core 1 by the take-up unit 8. FIG. 2 is a plan view of an electrode plate manufacturing apparatus using the manufacturing method of the present invention. The drying furnace 5 includes a heat exchanger 9 and a fan 10 for sending air. Hot air is sent into the inside to keep the temperature in the drying furnace 5 constant.

  FIG. 3 is a schematic view showing the arrangement of the electromagnetic induction coil 6, the electrode core material 1, the electrode plate 14 made of the mixture 4 and the nozzle 11 in the drying furnace 5 described above. By blowing the wind whose temperature and wind speed are controlled by the nozzle 11 against the electrode plate core 1 that generates heat by the electromagnetic induction coil 6, the temperature of the electrode plate core 1 is prevented from increasing rapidly and the temperature is controlled. The evaporated solvent is continuously removed from the surface of the paste-like mixture 4, thereby improving the drying efficiency.

  Hereinafter, one embodiment of the present invention will be described in more detail using an electrode plate manufacturing apparatus using an electrode plate in which a negative electrode mixture is applied to a strip-shaped electrode plate core material.

In Example 1 of the present invention, as shown in FIG. 1, as an inlet means, an electrode plate core 1 made of copper foil having a thickness of 10 μm and a width of 130 mm wound around the unwinding portion 2 is used as an entrance roller 13. And through the exit roller 16 through the drying furnace 5 and taken up by the take-up unit 8. Further, the winding speed of the winding section 8 is made faster than the unwinding speed of the unwinding section 2, a tension of 10 to 50 kgf is applied to the electrode plate core 1, and the coating die nozzle 3 disposed on the inlet roller 13 is combined. One side of the electrode core material 1 is formed by discharging the agent 4 and providing a solid portion where the mixture 4 is not applied at both ends in the width direction of the electrode plate core material 1 at a traveling speed of the electrode plate core material 1 of 4 to 10 m / min. Only on the whole surface, and is carried into the drying furnace 5. In addition, one side of the remaining electrode core material 1 that was not applied thereafter was applied and dried in the same manner to produce an electrode plate 14 having a thickness of 270 μm including the thickness of the electrode plate core material 1.
In the drying furnace 5, as shown in FIG. 3, the electromagnetic induction coil 6 having a width of 110 mm and an output of 364 W uses an electromagnetic induction coil having a width narrower than that of the electrode plate 14, and is The electromagnetic induction coil 6 is placed at the bottom, the distance between the electrode plate 14 and the upper surface of the electromagnetic induction coil 6 is 17 mm, and the nozzle 11 connected to the hot air generator 15 by a heat-resistant hose is arranged in the width direction of the electrode plate 14. Arranged in two places on the upper surface. Next, a current is transmitted from the high frequency generator 7 connected to the electromagnetic induction coil 6, and hot air having a temperature of 60 ° C. and a wind speed of 3.2 m / sec is set in the vicinity of the electrode plate 14 for the hot air generator 15. It was discharged from the nozzle 11 connected to the hot air generator 15 and sprayed onto the electrode plate 14.

In addition, the hot air in which the temperature is controlled to 60 ° C. and the wind speed to 3.2 m / sec by the heat exchanging unit 9 and the fan 10 is discharged into the first chamber of the drying furnace 5 having three chambers, and the hot air temperature in the second chamber is The hot air set at 80 ° C., the wind speed of 6 m / sec, the hot air temperature of the third chamber at 120 ° C. and the wind speed of 6 m / sec, respectively, is released, and the temperature in the drying furnace 5 is kept constant. The electrode plate 14 was run in the direction of the arrow and dried.
As a result, the temperature of the portion 10 mm inside from the end of the electrode plate 14 was kept at 65 ° C., and the oxidation of the electrode plate core material 1, which was a copper foil, was suppressed.

Further, the amount of water evaporation of the electrode plate 14 after passing through the first chamber in which the electromagnetic induction coil 6 is installed is 23%, and the electrode plate 14 10 mm inside from the end of the electrode plate core 1 where the magnetic flux concentrates. The surface was not cracked and was in the same state as the central portion of the electrode plate 14. The evaluation by the peel test showed the same binding strength at the end portion and the central portion of the electrode plate 14.

  Here, in the case where hot air is not discharged from the nozzle 11, the temperature becomes 120 ° C. when the portion 10 mm inside from the end of the electrode plate core 1 is measured, and oxidation of the electrode plate core 1, which is a copper foil, is observed. Although the moisture evaporation amount of the electrode plate 14 when passing through the first chamber of the drying furnace 5 is not measured, the dry state is 17.5%, which is worse than when dried by the manufacturing apparatus of the present invention. The binding strength at the ends of the end portions and the center portion of the electrode plate 14 was lower than that at the center portion.

  Further, when the width of the electromagnetic induction coil 6 is the same as that of the electrode plate core material 1, when the temperature of the portion 10 mm inside from the end of the electrode plate core material 1 is measured, the temperature becomes 290 ° C. at the highest portion. In addition, oxidation is observed in the electrode plate core 1 made of copper foil, and the surface of the electrode plate 14 10 mm inside from the end of the electrode plate core 1 where the magnetic flux is concentrated generates cracks and pinholes on the crater due to boiling. The state was different from the central part of the electrode plate 14.

  In Example 2 of the present invention, as shown in FIG. 4, the nozzle 11 installed in the drying furnace 5 is installed in a direction perpendicular to the width direction of the electrode plate 14, and the electrode is arranged in the direction of the arrow in FIG. The electrode plate 14 was dried in the same manner as in Example 1 while running the plate 14. As a result, the same result as in Example 1 was obtained, and the dry state of the electrode plate 14 was good.

In Example 3 of the present invention, as shown in FIG. 5, the upper nozzle 21 installed in the drying furnace 5 is installed upward with respect to the electrode plate 14, and the lower nozzle 22 is installed with respect to the electrode plate 14. It installed in the downward direction with the electromagnetic induction coil 6 interposed.
Further, in the electromagnetic induction coil 6, only the coils of the electromagnetic induction coil 6 are connected to each other so that the hot air discharged from the lower nozzle 22 passes between the coils of the electromagnetic induction coil 6 and is blown to the electrode plate 14. The electrode plate 14 was run in the direction of the arrow in the figure, and the electrode plate 14 was dried in the same manner as in Example 1. As a result, the same results as in Example 1 were obtained, and the dry state of the electrode plate 14 was good. In particular, the electrode plate 14 in which the mixture 4 was applied to the electrode plate core 1 simultaneously on both sides was effective and productive. Improvement was seen.

  In Example 4 of the present invention, as shown in FIG. 6, the electromagnetic induction coil 6 is placed below the electrode plate core 1, and the distance between the electrode plate core 1 and the upper surface of the electromagnetic induction coil 6 is 17 mm. Arranged. The positions of the end of the electrode plate core 1 and the end of the electromagnetic induction coil 6 are aligned so that the magnetic flux is concentrated on the end of the electrode plate core 1. The ferrite cores 12 having a width of 20 mm and a thickness of 5 mm are disposed at both end portions of the electromagnetic induction coil 6 at positions parallel to the width direction of the electrode plate core material 1. When a current is transmitted from the high frequency generator 7 connected to the electromagnetic induction coil 6 while the electrode core 1 is stopped without running, and the temperature of the end of the electrode core 1 is measured after 15 seconds, the electrode core is measured. Even at the highest temperature part 10 mm inside from the end of 1, the temperature became 100 ° C., and the oxidation of the electrode plate core material 1, which was a copper foil, was suppressed, and the temperature could be controlled. This is because the high magnetic flux in the outer peripheral portion of the electromagnetic induction coil 6 is concentrated on the ferrite core 12, thereby controlling the amount of magnetic flux applied to the end portion of the electrode plate core material 1 to prevent the concentration. It is thought that fever was suppressed.

Moreover, the mixture 4 similar to Example 1 was apply | coated to the electrode plate core material 1 with the coating die nozzle 3 at the speed | rate of 4 m / min, and the electrode plate 14 was produced. The drying furnace 5 into which the electrode plate 14 is carried is composed of three chambers as in the first embodiment. In the first chamber, two sets of electromagnetic induction coils 6 having a capacity setting and a distance of 17 mm from the electrode plate 14 are secured. The coil 6 was placed under the electrode plate 14, and the end of the electrode plate core 1 and the end of the electromagnetic induction coil 6 were aligned so that the magnetic flux was concentrated on the end of the electrode plate core 1. Further, between the electromagnetic induction coil 6 and the electrode plate 14, the ferrite core 12 having a width of 20 mm and a thickness of 5 mm is positioned parallel to the width direction of the electrode plate core 1 at both end positions of the electromagnetic induction coil 6. Arranged. Further, the second chamber hot air temperature is set to 80 ° C. and the wind speed is 6 m / sec. The third chamber hot air temperature is set to 120 ° C. and the wind speed is 6 m / sec. went. As a result, the surface of the mixture 4 on the inner side 10 mm from the end of the electrode plate 14 where the magnetic flux is concentrated is not cracked and is in a state equivalent to the mixture 4 applied to the central portion of the electrode plate core 1. The binding strength was.
Here, in the case where the ferrite core 12 is not disposed between the electrode plate 14 and the electromagnetic induction coil 6, the highest temperature of the inner portion 10 mm from the end of the electrode plate core 1 is 290 ° C., which is a copper foil. The plate core material 1 was oxidized.
Similarly, in the electrode plate 14 in which the mixture 4 is applied to the electrode plate core 1, cracks and boiling occur on the surface of the mixture 4 10 mm inside from the end of the electrode plate core 1 where the magnetic flux concentrates. A pinhole on the crater was generated, which was different from the mixture 4 applied to the central portion of the electrode plate core 1, and the binding strength was low.
As described above, the electrode plate immediately after the mixture of the present invention is applied on the strip-shaped electrode plate core is continuously carried into a drying furnace equipped with an electromagnetic induction coil and a hot air generator, and the electrode plate By drying the electrode plate while keeping the temperature in the width direction constant, it is possible to prevent a sudden temperature rise that occurs partially in the electrode plate and obtain a uniform temperature, which is applied to the surface of the electrode plate The mixture can be dried efficiently. Furthermore, the plain portion of the electrode plate is not oxidized, and there is no extreme temperature unevenness, so that high-quality drying is possible, and it is possible to produce an electrode plate with stable quality.

  ADVANTAGE OF THE INVENTION According to this invention, when drying with an electromagnetic induction coil, the drying apparatus which can control temperature can be provided by controlling the magnetic flux concentration to the edge part of an electrode plate core material. Such a drying apparatus is not limited to the electrode plate core material which is a negative electrode current collector of a lithium secondary battery, but is a positive electrode current collector of a lithium secondary battery based on an electrode plate core material using a metal sheet. It can also be applied to aluminum sheet materials for electric double layer capacitors.

The schematic diagram of the manufacturing apparatus of the electrode plate which concerns on one Embodiment of this invention. The top view of the manufacturing apparatus of the electrode plate which concerns on one Embodiment of this invention. The schematic diagram which shows arrangement | positioning of the electromagnetic induction coil which concerns on Example 1 of this invention, an electrode plate core material, and a nozzle The schematic diagram which shows arrangement | positioning of the electromagnetic induction coil which concerns on Example 2 of this invention, an electrode plate core material, and a nozzle The schematic diagram which shows arrangement | positioning of the electromagnetic induction coil which concerns on Example 3 of this invention, an electrode plate core material, and a nozzle The schematic diagram which shows arrangement | positioning of the electromagnetic induction coil which concerns on Example 4 of this invention, an electrode plate core material, and a ferrite core

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrode plate core material 2 Unwinding part 3 Coating die nozzle 4 Mixture 5 Drying furnace 6 Electromagnetic induction coil 7 High frequency generating part 8 Winding part 9 Heat exchange part 10 Fan 11 Nozzle 12 Ferrite core 13 Inlet roller 14 Electrode plate 15 Hot air Generator 16 Outlet roller 21 Upper nozzle 22 Lower nozzle

Claims (2)

In a drying furnace equipped with an electromagnetic induction coil to which electric current is transmitted from a high-frequency generator and a hot air generator, a positive electrode mixture or a negative electrode mixture is partially or completely placed on a strip-shaped metal electrode plate core. a conveying means for continuously transferring the coated electrode plate of the electrode plate ferrite core between the electrode plates passing through said electromagnetic induction coils installed in the drying furnace in the drying oven Electrode plate manufacturing equipment installed at locations located at both ends. 2. The electrode plate manufacturing apparatus according to claim 1 , wherein the width of the electromagnetic induction coil is narrower than the width direction of the electrode plate.