JP2015044156A - Kneading device of electrode paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a kneading device of electrode paste which can shorten a kneading time for generating the electrode paste.SOLUTION: A kneading device generates electrode paste by kneading at least active material, CMC, and a solvent. Water W (a fluid) is pressurized by a high pressure water supplier 14 and is supplied to an acceleration nozzle 12 through a high pressure water supply pipe 11. Powder P (active material or the like) is supplied in the acceleration nozzle 12, and is accelerated in the acceleration nozzle 12 by the pressurized water W. A CMC water solution C is loaded in a loading nozzle 13 by a CMC water solution loader 21, and undissolved lumps of flour (lumps) contained in the CMC water solution C is broken into small pieces by the high-speed and hard active material or the like in the loading nozzle 13.

Description

  The present invention relates to a kneading apparatus for kneading at least an active material, carboxymethyl cellulose and a solvent to produce an electrode paste.

  For example, the electrode of the power storage device is formed by applying an electrode paste to a metal foil and performing a drying and pressurizing process and the like to form an active material layer. The electrode paste contains an active material, a conductive aid, a solvent, and the like. A kneading device is used when producing an electrode paste made of such substances. For example, the kneading apparatus of Patent Document 1 describes that an active material, a conductive agent, a thickener, a binder, and a solvent are mixed in a container. After mixing into the container, kneading / stirring is performed, and after the kneading progresses to a predetermined state, the paste is once sent out of the container through the discharge pipe, and again returned into the container through the delivery pipe. The paste returned by the delivery pipe is supplied along the inner wall surface of the container above the paste liquid level in the container, and is thinly stretched by a scraper so that it can be easily defoamed.

JP 2012-196595 A

  In the electrode paste, the electrode paste needs to have a certain degree of viscosity in order to make the active material in a good dispersion state and to be easily applied to the metal foil. Therefore, the electrode paste often contains a thickener as in Patent Document 1, and in recent years, carboxymethylcellulose (hereinafter referred to as CMC [Carboxymethylcellulose]) is frequently used as a negative electrode thickener. . CMC dissolves quickly in a solvent, but aggregate adhesion between particles (generally referred to as “mamako”) tends to occur. Once Mamasko, the penetration of the solvent into Mamasko is significantly hindered, making it difficult to dissolve in the solvent. Therefore, when kneading including CMC in a kneading apparatus, setting the kneading time on the assumption that the CMC in a mamaco state is dissolved in the solvent takes a very long time, and the kneading time becomes long.

  Then, this invention makes it a subject to provide the kneading apparatus of the electrode paste which can shorten the kneading | mixing time for producing | generating an electrode paste.

  The electrode paste kneading apparatus according to the present invention is a kneading apparatus for producing an electrode paste by kneading at least an active material, CMC and a solvent, and is accelerated by an acceleration means for accelerating the active material by a fluid, and the acceleration means. And a charging means for charging CMC into the active material.

  In this kneading apparatus, when a plurality of substances (at least the active material and CMC (thickening agent)) contained in the electrode paste are charged, a fluid (eg, liquid, gas) is pressurized and the pressure is increased to a high pressure. The active material is accelerated by the fluid. And in a kneading apparatus, CMC is thrown into the accelerated active material. The input CMC collides with a high-speed active material. Since the CMC collides with the active material in this manner, even if the mackerel is generated in the CMC, the macho is crushed and easily dissolved in the solvent when it is put into the kneading apparatus. Therefore, when kneading an active material, carboxymethylcellulose, a solvent, etc. in a kneading apparatus, the time until CMC is dissolved in the solvent and sufficiently dispersed can be shortened. Thus, in the kneading apparatus, by introducing CMC into the accelerated active material, the time until CMC is dissolved in the solvent can be shortened, and the kneading time for generating the electrode paste can be shortened. When the kneading time is shortened, the electrode manufacturing cycle can be shortened.

  In the above-described electrode paste kneading apparatus of the present invention, it is preferable that CMC is introduced as an aqueous solution. In this kneading apparatus, the CMC aqueous solution is put into the accelerated active material. The charged CMC aqueous solution includes one in which the CMC is in a mamako state. However, the charged CMC aqueous solution collides with the high-speed active material, and the hard active material is crushed into a small state. Therefore, kneading / stirring in the CMC's state can be suppressed. Thus, CMC crushed from Mamako increases the area in contact with water (solvent), and is easily dissolved in water. The time until CMC is dissolved in the solvent can be shortened.

  In the electrode paste kneading apparatus of the present invention, it is preferable that the charging means is charged in the form of a mist of an aqueous solution of CMC. In this kneading apparatus, a mist-like CMC aqueous solution to be put into the accelerated active material is charged. By making the CMC aqueous solution mist, it is possible to reduce mamako contained in the CMC aqueous solution, and to further suppress kneading and stirring of the CMC in the mamaco state. As a result, the time until CMC is dissolved in water can be further shortened.

  According to the present invention, by introducing CMC into the accelerated active material, the time until CMC dissolves in the solvent can be shortened, and the kneading time for generating the electrode paste can be shortened.

It is sectional drawing which shows typically the injection | throwing-in part of the kneading apparatus of the electrode paste which concerns on 1st Embodiment. It is sectional drawing which shows typically the injection | throwing-in part of the kneading apparatus of the electrode paste which concerns on 2nd Embodiment.

  Hereinafter, an embodiment of an electrode paste kneading apparatus according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected about the element which is the same or it corresponds in each figure, and the overlapping description is abbreviate | omitted.

  In the present embodiment, the electrode paste kneading apparatus according to the present invention is applied to a kneading apparatus for generating an electrode paste for an electrode of a power storage device. In this embodiment, there are two embodiments for the charging unit of the kneading apparatus. In this embodiment, the manufactured electrode is a negative electrode of a lithium ion secondary battery.

  In the manufactured negative electrode, an electrode paste is applied to at least one surface of a metal foil, and an active material layer is formed through a drying process, a pressing process, and the like. The negative electrode also has a tab to which no electrode paste is applied. The metal foil in the present embodiment is, for example, a copper foil. The electrode paste contains an active material, a conductive additive, a thickener, and a solvent. The active material is a negative electrode active material, for example, carbon such as graphite, highly oriented graphite, mesocarbon microbeads, hard carbon, soft carbon, alkali metals such as lithium and sodium, metal compounds, SiOx (0.5 ≦ 0.5 a metal oxide such as x ≦ 1.5) or boron-added carbon. Examples of the conductive assistant include carbon black, graphite, acetylene black, and ketjen black. The solvent is water. The thickener is CMC (carboxymethylcellulose). The electrode paste may contain a binder such as a thermoplastic resin such as polyamideimide or polyimide, or a polymer resin having an imide bond in the main chain.

  The CMC of the thickener is in a state of an aqueous solution mixed with solvent water before being charged into the kneading apparatus. Although CMC dissolves quickly in water, mamako (dama), which is an aggregate adhesion between particles in the process of forming an aqueous solution, is likely to occur. Mamako is significantly impeded by the penetration of water into the interior. For this reason, in a CMC aqueous solution containing a large amount of Mamako, it takes a very long time to completely dissolve Mamako in water. Therefore, in the present embodiment, a CMC aqueous solution containing mamako is used, and a structure in which mamako contained in the CMC aqueous solution is reduced in the charging unit is adopted.

  The kneading apparatus according to the present embodiment includes a container main body and a charging unit for charging an active material, a conductive additive, a solvent and the like into the container main body in addition to the thickener as described above. And a kneading / stirring section for kneading / stirring an active material, a conductive additive, a thickener, a solvent and the like in the container body. The kneading / stirring section is, for example, a stirring blade. Conventionally well-known parts can be applied to each part other than the charging part such as the kneading / stirring part in the kneading apparatus.

  With reference to FIG. 1, the charging unit 1 of the kneading apparatus according to the first embodiment will be described. FIG. 1 is a cross-sectional view schematically showing a charging portion of the electrode paste kneading apparatus according to the first embodiment.

  In the charging unit 1, water is supplied downward at high pressure from the top, and the active material and conductive aid are mixed in the high-pressure water stream to accelerate the active material and conductive aid downward. Further, in the charging unit 1, the CMC aqueous solution is mixed in the active material and the conductive additive accelerated by the high-pressure water flow. The mixed active material, conductive additive and CMC aqueous solution are put into the container body. In addition, when a binder is also included in an electrode paste, a binder may be mixed with an active material and a conductive support agent, and a binder may be thrown in another process.

  The charging unit 1 includes a housing 10, a high-pressure water supply pipe 11 that extends through the housing 10 in the axial direction, an acceleration nozzle 12, and a charging nozzle 13. The high-pressure water supply pipe 11, the acceleration nozzle 12, and the injection nozzle 13 are all hollow tubular members and are held by the housing 10. The lower end portion of the high pressure water supply pipe 11 is fitted and connected to the inner surface of the upper end portion of the acceleration nozzle 12. The lower end portion of the acceleration nozzle 12 is disposed at the upper end portion of the internal space of the charging nozzle 13. The diameter of the injection nozzle 13 is larger than the diameter of the acceleration nozzle 12. A container body (not shown) is disposed below the injection nozzle 13.

  At the other end of the high pressure water supply pipe 11, a high pressure water supply device 14 for supplying water W to the high pressure water supply pipe 11 at a high pressure is attached. The high-pressure water supply unit 14 includes a storage tank for water W, a high-pressure pump, and the like, and can adjust the pressure, timing, and the like when supplying the water W. Such adjustment control is performed by a kneading device or a control device (not shown) of the upper electrode production line.

  A hopper 15 is disposed on the side of the housing 10. The hopper 15 stores a powder P such as an active material or a conductive aid, and supplies the powder P into the housing 10. The tip of the hopper 15 is attached to the side surface of the housing 10. On the side surface of the housing 10, an opening 16 is opened at the position of the attachment portion of the tip portion of the hopper 15. A groove 17 is formed in the housing 10 so as to surround the acceleration nozzle 12 from the opening 16. The groove 17 has a hollow donut shape surrounding the acceleration nozzle 12, and communicates with the hopper 15 through the opening 16 on the side surface of the housing 10. A supply port 18 for supplying the powder P from the groove 17 is opened at a position corresponding to the groove 17 on the side wall of the acceleration nozzle 12. The supply port 18 is disposed on the side wall of the acceleration nozzle 12 on the side opposite to the side where the opening 16 for supplying the powder P from the hopper 15 is located. As described above, the hopper 15 for supplying the powder P communicates with the internal space of the acceleration nozzle 12 through the groove 17 and the supply port 18 through the opening 16 on the side surface of the housing 10. Note that a screw or the like for forcibly feeding the powder P may be provided in the hopper 15.

  On the side surface of the housing 10, an insertion port 19 is opened at a position below the opening 16. An input pipe 20 is attached to the input port 19. A CMC aqueous solution charging device 21 for charging the CMC aqueous solution C is attached to the other end of the charging tube 20. The CMC aqueous solution feeder 21 includes a storage tank, a pump, and the like for the CMC aqueous solution C, and can adjust the pressure and timing when the CMC aqueous solution C is charged. This adjustment control or the like is performed by a kneading apparatus or a control apparatus of an upper electrode production line. A groove 22 is formed in the housing 10 so as to surround the acceleration nozzle 12 from the charging port 19. The groove 22 has a hollow donut shape surrounding the acceleration nozzle 12, and is open so that the lower part is connected to the upper end of the injection nozzle 13. The position of the lower end of the inlet 19 and the position of the upper end of the inlet nozzle 13 are the same height position. In this way, the inlet 19 into which the CMC aqueous solution C is introduced through the inlet pipe 20 communicates with the upper end of the inlet nozzle 13 via the groove 22, and further, the outer surface of the side wall of the acceleration nozzle 12 and the inlet nozzle. 13 communicates with the inner space of the injection nozzle 13 through a gap with the inner surface of the side wall.

  In the first embodiment, the high-pressure water supply pipe 11, the high-pressure water supply 14, the acceleration nozzle 12, the hopper 15, the opening 16, the groove 17, and the supply port 18 are the acceleration means described in the claims. The charging port 19, the charging pipe 20, the CMC aqueous solution charging device 21, the groove 22, the acceleration nozzle 12, and the charging nozzle 13 correspond to the charging means described in the claims.

  The operation of the charging unit 1 configured as described above will be described. The high-pressure water supplier 14 pressurizes the water W and supplies the high-pressure water W to the high-pressure water supply pipe 11. The high-pressure water W enters the acceleration nozzle 12 through the high-pressure water supply pipe 11 and flows through the acceleration nozzle 12. Since high-pressure water W flows in the acceleration nozzle 12, a suction force that is drawn into the acceleration nozzle 12 at the supply port 18 is generated by this high-pressure water flow.

  Due to the negative pressure due to the suction force, the powder P (active material, conductive additive, etc.) is drawn into the acceleration nozzle 12 from the hopper 15 through the opening 16, the groove 17, and the supply port 18. At this time, the powder P may be mechanically sent out continuously by a screw or the like in the hopper 15. The powder P drawn into the acceleration nozzle 12 is mixed with the high-pressure water W flowing through the acceleration nozzle 12 to form a suspension containing the powder P. Further, since the acceleration nozzle 12 is disposed in the vertical direction, the powder P is subjected to gravity in the acceleration nozzle 12. Therefore, the powder P is accelerated in the acceleration nozzle 12 by this high-pressure water flow and gravity, and descends at a high speed. The high-speed powder P and water W enter the injection nozzle 13 from the acceleration nozzle 12. In addition, since the supply port 18 of the powder P into the acceleration nozzle 12 is formed on the opposite side of the opening 16 connected to the hopper 15, the powder P is brought into the hopper by the high pressure of the water W flowing in the acceleration nozzle 12. There is no reverse flow to the 15 side.

  In the CMC aqueous solution feeder 21, the CMC aqueous solution C is supplied to the charging pipe 20. The CMC aqueous solution C also includes CMC that has become mamako (dama). The CMC aqueous solution C enters the gap between the outer surface of the side wall of the accelerating nozzle 12 and the inner surface of the side wall of the charging nozzle 13 via the charging pipe 20, the charging port 19, and the groove 22, and further enters the charging nozzle 13 through the gap. . A high-speed powder P (suspension mixed with water W) flows in the charging nozzle 13, and the CMC aqueous solution C having a low flow velocity is mixed with the high-speed powder P. Therefore, a high-speed hard active material or the like collides with Mamako contained in the CMC aqueous solution C, and Mamako is crushed into a powder having a small CMC. Thus, the CMC powder crushed from Mamako increases the area in contact with water and is easily dissolved in water. In addition, in order to crush the mamako contained in the CMC aqueous solution with a high-speed active material or the like, it is necessary to pressurize the water W to a high pressure by the high-pressure water supplier 14 so that the active material or the like can be accelerated to such an extent that mamako can be broken. The pressure value of the high-pressure water W and the output of the high-pressure pump necessary for pressurization up to the pressure value may be set as appropriate in experiments and the like.

  In this way, the CMC aqueous solution C containing mamako, powder P (active material, conductive additive, etc.), and water W are mixed, discharged from the charging nozzle 13, and charged into the container body. When kneading / stirring in this container body, CMC that has been crushed and reduced by Mamako is easy to dissolve in water, so in the process of kneading / stirring in the container body, until CMC dissolves and Mamako is eliminated. Time is shortened. As a result, the time until CMC, the active material, the conductive additive, etc. are dissolved in water (solvent) and sufficiently dispersed is shortened, and the kneading time is shortened.

  According to the kneading apparatus provided with the charging unit 1, by introducing the CMC aqueous solution into the accelerated active material or the like, it is possible to reduce CMC mamako and shorten the time until the CMC is dissolved in water (solvent). The kneading time for generating the electrode paste can be shortened. When the kneading time is shortened, hard powder such as an active material can be prevented from wearing the container body and the stirring blade during kneading and stirring, and foreign matter due to wear can be prevented from being mixed into the electrode paste. As a result, since the generation of pinholes and cracks due to contamination of foreign materials in the active material layer of the electrode can be suppressed, the performance as an electrode can be prevented from being impaired, and a high-quality electrode can be manufactured. Further, when the kneading time is shortened, the electrode manufacturing cycle can be shortened.

  With reference to FIG. 2, the charging unit 2 of the kneading apparatus according to the second embodiment will be described. FIG. 2 is a cross-sectional view schematically showing a charging portion of the electrode paste kneading apparatus according to the second embodiment.

  The input unit 2 differs from the input unit 1 according to the first embodiment only in that the CMC aqueous solution is supplied in the form of a mist. Therefore, the configuration of the portion where the CMC aqueous solution is charged in the charging unit 2 will be described in detail.

  Similarly to the charging unit 1 according to the first embodiment, the charging port 2 is also provided with a charging port 19 on the side surface of the housing 10, and a groove 22 communicating with the charging port 19 is formed in the housing 10. ing. In particular, in the charging unit 2, a charging tube 23 is attached to the charging port 19. An air supply 24 for supplying high-pressure air A is attached to the other end side of the input pipe 23. In the middle of the input pipe 23, a pipe throttle part 25 having a pipe diameter thinner than the other part is provided. The tube restricting portion 25 has the same structure as the carburetor. The tube restricting portion 25 is formed with an opening connected to the CMC aqueous solution injector 21 via the connecting tube 26, and the high pressure supplied from the air supply device 24. The air A is accelerated at the tube restricting portion 25, so that a negative pressure acts on the opening, sucks out the CMC aqueous solution C, and makes the CMC aqueous solution C mist. In the second embodiment, the charging pipe 23 and the charging port 19 provided with the pipe throttle portion 25, the CMC aqueous solution charging device 21, the groove 22, the acceleration nozzle 12, the charging nozzle 13, the air supply device 24, the connection The tube 26 corresponds to the input means described in the claims.

  The operation of the charging unit 2 configured as described above will be described. In the second embodiment, since the operations other than the addition of the CMC aqueous solution C are the same as those in the first embodiment, only the operation related to the addition of the CMC aqueous solution C will be described.

  In the CMC aqueous solution dispenser 21, the CMC aqueous solution C is supplied to the introduction tube 23 from the tube restricting portion 25. The CMC aqueous solution C immediately after being supplied from the CMC aqueous solution feeder 21 contains a large amount of CMC that has become mamako (dama). In the air supplier 24, high-pressure air A is supplied to the input pipe 23. The CMC aqueous solution C supplied from the tube restricting portion 25 into the input tube 23 is atomized by the tube restricting portion 25. By making the CMC aqueous solution C into a mist in this way, a part of Mamako contained in the CMC aqueous solution C is also finely divided. In this way, the powder of CMC finely divided from Mamako increases the area in contact with water, makes it easy for water to penetrate into the inside, and dissolves easily in water. The mist-like CMC aqueous solution C (CMC aqueous solution C in which mamako is suppressed) is interposed between the outer surface of the side wall of the accelerating nozzle 12 and the inner surface of the side wall of the charging nozzle 13 via the charging port 19 and the groove 22. And enters the injection nozzle 13 through the gap. Since the high-speed powder P flows in the charging nozzle 13, the CMC aqueous solution C is mixed with the high-speed powder P. Then, a high-speed hard active material or the like collides with Mamako remaining in the CMC aqueous solution C, and Mamako is crushed into a powder having a small CMC. The CMC aqueous solution C, powder P (active material, conductive auxiliary agent, etc.) and water W mixed together in this way are mixed, discharged from the charging nozzle 13, and loaded into the container body. Mamako contained in the CMC aqueous solution C charged into the container body is smaller than that of the charging unit 1 according to the first embodiment. Therefore, when kneading and stirring in the container body, the time until CMC is dissolved in water is further shortened. As a result, the time until CMC, the active material, the conductive auxiliary agent, etc. are dissolved in water (solvent) is further shortened, and the kneading time is very short.

  The kneading apparatus provided with the charging unit 2 has the following effects in addition to the same effects as those of the first embodiment. According to this kneading apparatus, by adding the CMC aqueous solution in the form of a mist, it is possible to suppress mamako contained in the CMC aqueous solution, and to further suppress the addition to the kneading / stirring container body in the mamaco state. As a result, the time until the CMC is dissolved in the solvent can be further shortened, and the kneading time for producing the electrode paste can be further shortened.

  As mentioned above, although embodiment which concerns on this invention was described, this invention is implemented in various forms, without being limited to the said embodiment.

  In the present embodiment, the negative electrode paste of the lithium ion secondary battery has been described. However, the present invention is not limited to the lithium ion secondary battery, and is not limited to the negative electrode paste. . As long as it contains CMC as a thickener, it can also be applied to a positive electrode paste kneading apparatus or another battery electrode paste kneading apparatus.

  In this embodiment, water is used as the fluid supplied at a high pressure. However, a liquid other than water may be used as long as it is a solvent. For example, other solvents such as organic solvents such as NMP (N-methylpyrrolidone), methanol, and methyl isobutyl ketone can also be used. Gas can also be used. In this embodiment, CMC is added as an aqueous solution, but CMC may be added in a powder state. In this case, the occurrence of mamako when it comes into contact with water in the charging section is hindered by the collision with the active material.

  In the present embodiment, an example of a configuration for pressurizing a fluid (water), a configuration for accelerating an active material or the like by a pressurized fluid, and a configuration for introducing CMC into an accelerated active material or the like is shown. However, various other configurations can be applied to each of these configurations. Further, in the second embodiment, an example of a configuration in which the CMC aqueous solution is made into a mist is shown, but various other configurations can be applied to this configuration.

  DESCRIPTION OF SYMBOLS 1, 2 ... Injection part, 10 ... Housing | casing, 11 ... High pressure water supply pipe, 12 ... Acceleration nozzle, 13 ... Injection nozzle, 14 ... High pressure water supply device, 15 ... Hopper, 16 ... Opening part, 17, 22 ... Groove , 18 ... supply port, 19 ... input port, 20, 23 ... input tube, 21 ... CMC aqueous solution input device, 24 ... air supply device, 25 ... tube throttling part, 26 ... connecting tube.

Claims (3)

A kneading apparatus for producing an electrode paste by kneading at least an active material, carboxymethyl cellulose and a solvent,
Accelerating means for accelerating the active material by the fluid;
Input means for introducing carboxymethylcellulose into the active material accelerated by the acceleration means;
An electrode paste kneading apparatus comprising:   2. The electrode paste kneading apparatus according to claim 1, wherein the carboxymethyl cellulose is charged as an aqueous solution.   3. The electrode paste kneading apparatus according to claim 2, wherein the charging means charges the aqueous solution of the carboxymethyl cellulose in the form of a mist.

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