JP5699951B2 - Manufacturing method of secondary battery - Google Patents

Description

  The present invention relates to a method for manufacturing a secondary battery using an electrode plate having an active material layer. More specifically, the present invention relates to a method of appropriately manufacturing an electrode mixture paste for forming an active material layer in an electrode plate and manufacturing a secondary battery using the electrode mixture paste.

  A secondary battery usually has a configuration in which positive and negative electrode plates are wound together with a separator and housed in a case. The electrode plate is a current collector foil coated with an active material layer. Therefore, an electrode plate is manufactured by coating the metal foil used as current collection foil with the paste containing an active material component, and drying it. Naturally, the paste is manufactured by kneading a powdery active material component and a liquid solvent component. As the prior art relating to the manufacture of the paste, the one described in Patent Document 1 can be cited. In the technique of Patent Document 1, a reagent liquid is dropped on the electrode active material powder, and the kneading torque is measured. The properties of the electrode active material are evaluated based on the relationship between the amount of reagent liquid dropped and the kneading torque. This is because various conditions at the time of manufacturing the paste are determined based on the properties thus evaluated.

JP 2005-285606 A

  By the way, what is evaluated by the technique of Patent Document 1 is the properties of pure electrode active material powder. On the other hand, the powder component when actually producing a paste by kneading is not limited to the electrode active material. Additives such as thickeners may be included. For this reason, the technique of Patent Document 1 has a problem that the properties of the actual paste cannot be appropriately evaluated.

  In addition, as the electrode active material, a material in which the surface of graphite particles is coated with an amorphous film may be used. In the process of manufacturing the electrode active material, the graphite particles that exist individually are coated with an amorphous film, and a lump in which these particles adhere to each other is formed (granulation). Therefore, after that, the crushing process to loosen the lump was performed, but it was difficult to perform the crushing process to separate all the lumps into complete particles. For this reason, a part of the lump may remain in the completed electrode active material. Such a lump of the electrode active material is not loosened by the kneading degree for evaluating the properties of the powder component. However, in the kneading process for producing an actual electrode mixture paste, the lump is loosened and separated into particles of the electrode active material. In other words, the particle size distribution is different between the powder component during preliminary kneading and the powder component during main kneading. As a result, there was a problem that the actual paste properties differed from the properties evaluated in advance.

  The present invention has been made for the purpose of solving the problems of the prior art described above. That is, the subject is to manufacture an electrode mixture paste with good properties using an electrode active material obtained by coating graphite particles with an amorphous film, and to manufacture a secondary battery using the electrode mixture paste. Is to provide a method.

  In order to solve this problem, the method for manufacturing a secondary battery according to the present invention is to manufacture an electrode mixture paste by kneading the powder component and the solvent component of the electrode mixture layer of the secondary battery, A method of manufacturing a secondary battery using an electrode plate having an electrode mixture layer formed on the basis of a material paste, wherein the powder component used when preparing the electrode mixture paste includes graphite particles. A powder component that contains a powder of an electrode active material whose surface is coated with amorphous carbon as a core, and that is used when preparing electrode mixture paste using powder of graphite particles before coating with amorphous carbon The other components are the same as the powder components used when creating the electrode mixture paste, and the same components as the solvent components used when creating the electrode mixture paste. Solvent , While injecting while measuring the liquid absorption amount, preliminarily kneading the powder and the injected solvent while measuring the kneading torque, the amount of the powder component at the start of premixing and kneading at the premixing An electrode mixture paste is produced by main kneading, in which the powder component and solvent component of the electrode mixture paste are mixed and kneaded at a mixing ratio equal to the ratio of the cumulative supply amount of the solvent when the torque shows the maximum value. And a method of manufacturing a secondary battery.

  In this secondary battery manufacturing method, first, preliminary kneading is performed. The purpose of the pre-kneading is to determine the blending ratio of the powder component and the solvent component during the main kneading for producing the actual electrode mixture paste prior to the main kneading. Here, in the electrode mixture paste used in the method for manufacturing a secondary battery, a material in which the surface of graphite particles is coated with amorphous carbon is used as an electrode active material. The characteristics of this electrode active material powder differ before and after the main kneading. Therefore, in the preliminary kneading, the powder of the electrode active material is used in the main kneading, but the powder of graphite particles is used instead. This is because the electrode active material after the main kneading and the graphite particles before coating with the amorphous carbon serving as the core thereof have almost the same particle size distribution, and therefore the characteristics are almost the same. The other component powders are the same as those used during the main kneading. That is, in the preliminary kneading, the same powder component as that used during the main kneading is used as the powder component except that the electrode active material powder is replaced with graphite particle powder. As the solvent component, the same solvent component as used during the main kneading is used. In the preliminary kneading, the ratio of the powder component and the solvent component when the kneading torque becomes maximum is determined as the blending ratio at the time of the main kneading. Next, the main kneading of the powder component and the solvent component is performed according to the blending ratio. As a result, an electrode mixture paste having good properties can be obtained with a blending ratio that matches the characteristics of the raw materials used.

  The present invention is particularly significant when the average particle diameter of the electrode active material is 20 μm or less. The characteristics of the electrode active material powder having an average particle size of 20 μm or less greatly differ before and after the main kneading. However, by using the powder of graphite particles before the coating of amorphous carbon in the pre-kneading, it is possible to find a blending ratio that matches the characteristics of the active material powder after the main kneading.

Further, the present invention provides a method for producing a secondary battery as described above, wherein in the main kneading, the mixing ratio of the electrode mixture paste is continued after the mixing of the powder component and the solvent component of the electrode mixture paste at the mixing ratio. The present invention also extends to a method for manufacturing a secondary battery, characterized in that adjustment kneading is performed to adjust the temperature to the required specifications from the lower process.

  According to the present invention, there is provided a method for producing a secondary battery using an electrode active material obtained by coating graphite particles with an amorphous film and producing an electrode material paste having good properties. Is provided.

It is sectional drawing which shows the structure of the absorption measuring device used by this form. It is a graph which shows the typical example of the fluctuation | variation of the kneading | mixing torque of a stirrer when the quantity of powder is made constant and the amount of solvents is increased gradually. It is a graph which shows the result of the torque measurement in the dripping preliminary kneading | mixing of the sample for negative electrodes. It is a graph which shows the final viscosity of the paste for negative electrodes. It is a graph which shows the particle size distribution of the natural graphite and the active material before and after the main kneading.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below in detail with reference to the accompanying drawings.

  First, a negative electrode of a secondary battery manufactured by the method of this embodiment uses an active material in which the surface of graphite particles is coated with an amorphous film. The average particle diameter (D50) of the active material is 20 μm or less. The graphite particles in the present embodiment are artificial graphite obtained from pitch as a precursor, natural graphite, and the like. When such graphite particles are exposed, there is a risk that a deteriorated film is formed by contact with the electrolytic solution. That is, when the graphite particles are used as active materials as they are, there is a risk that the battery characteristics of the secondary battery will deteriorate. The main purpose of preventing this is to cover the surface of the graphite particles with an amorphous film. The amorphous film in this embodiment is a film made of amorphous carbon.

In this embodiment, a secondary battery using the active material as described above is manufactured by the following procedure.
1. Determination of compounding ratio of electrode mixture paste (hereinafter simply referred to as paste) ↓
2. Paste manufacturing ↓
3. Lower process (application, winding, storage, etc.)

  Of these, “3. Downstream process” has no particular difference from the conventional process. The features of this embodiment are “1. Determination of blending ratio of paste” and “2. Production of paste”. In particular, “1. Determination of blending ratio of paste” is the core of the present invention. First, “1. Determination of blending ratio of paste” will be described.

  In this embodiment, the blending ratio is determined prior to manufacturing the paste. That is, the blending ratio between the powder component and the solvent component is determined when manufacturing an actual paste. The powder component used in the actual manufacture of the paste is mainly an active material powder that is completed by coating graphite particles with an amorphous film, but it is not the only one. It is a mixed powder containing powders of additives such as thickeners. Therefore, when determining the blending ratio, the same blending ratio of each synthetic powder in the mixed powder used when the actual paste is manufactured is used. However, as the mixed powder for determining the blending ratio, an active material powder is used as a mixed powder for actual paste production, and a graphite particle powder is used as an active material component instead. That is, when determining the compounding ratio, graphite particles before the coating of the amorphous film serving as the core of the active material are used. The other component powders of the other additives are the same as those used in actual production. Of course, the solvent component is the same as the solvent used in the actual production. When a mixture of two or more liquids is used as the solvent, the mixing ratio is the same as in actual production.

  Determination of the compounding ratio of the powder component and the solvent component in this embodiment is performed by performing preliminary kneading. Here, the preliminary kneading is to find the optimum blending ratio by kneading the powder and the solvent while changing the blending ratio. For this preliminary kneading, an oil absorption measuring device according to JIS-K5101-13-2 is used. For that purpose, for example, an absorption measuring device 1 having a structure as shown in FIG. 1 can be used.

  The absorption amount measuring device 1 in FIG. 1 includes a stirring container 2, a stirring bar 3, a liquid injection nozzle 4, and a funnel 5. The stirring container 2 is a container for pre-kneading the powder 6 and the solvent 7. A stirring bar 3 is provided in the stirring vessel 2. The stirrer 3 is, of course, for stirring the powder 6 and the solvent 7 in the stirring vessel 2 for preliminary kneading. The stirrer 3 in this embodiment can measure torque during stirring (referred to as kneading torque in the present application). Further, the rotation speed of the stirring bar 3 can be adjusted. The liquid injection nozzle 4 supplies a solvent to the stirring vessel 2. The liquid injection nozzle 4 in this embodiment can grasp the supply amount of the solvent. The funnel 5 is attached to the inlet of the stirring vessel 2 and guides the solvent supplied from the liquid injection nozzle 4 into the stirring vessel 2 without leakage.

  The preliminary kneading using the absorption amount measuring machine 1 having the above-described configuration is performed as follows. First, only the powder 6 out of the powder 6 and the solvent 7 is stored in the stirring vessel 2. Of course, the amount P of the contained powder 6 is recorded. Then, the solvent 7 is dropped from the liquid injection nozzle 4 while the stirrer 3 is driven. Thereby, the amount of the solvent 7 is gradually increased while the amount of the powder 6 in the stirring vessel 2 is kept constant. In this process, the fluctuation of the kneading torque is recorded while keeping the rotation speed of the stirring bar 3 constant.

  Then, generally, a graph as shown in FIG. 2 is obtained. In the graph of FIG. 2, the vertical axis indicates the kneading torque. The horizontal axis indicates the solid content ratio that is the weight ratio of the powder 6 in the paste. That is, the cumulative amount of the dropped solvent 7 increases as it goes to the right (lower solid fraction). As shown in FIG. 2, the kneading torque is small at the beginning, and the kneading torque increases as the amount of the solvent 7 increases. This is considered to be due to the fact that by adding the solvent 7 to the powder 6 in the dry state, a paste in which the powder 6 and the solvent 7 are mixed is generated and the amount of the paste is gradually increased. In addition, it is considered that the effect of the thickener contained in the powder 6 appears as the amount of the solvent 7 increases. However, the kneading torque exhibits a peak T at a certain solid content, and thereafter, the kneading torque decreases as the amount of the solvent 7 increases. This is considered to be because when the amount of the solvent 7 becomes excessive, the paste becomes diluted and the viscosity decreases. Therefore, the ratio P: S between the amount of powder P and the amount of solvent S when the kneading torque shows a peak T in the process of FIG. 2 is determined as the blending ratio of the paste. Here, the solvent amount S is the cumulative supply amount of the solvent from the start of the supply of the solvent 7 from the injection nozzle 4 to the peak time of the kneading torque.

  Therefore, the subsequent “2. Paste production” step is performed with the blending ratio P: S determined as described above. That is, the ratio of the amount of powder used in the actual manufacturing process and the amount of solvent is made equal to the above-mentioned blending ratio P: S. However, as described above, the powder used in the actual manufacturing process is not the graphite particle powder used in the preliminary kneading, but the finished active material powder. The actual manufacturing process itself may be performed by a conventional method. As a result, the blending ratio is appropriately matched to the characteristics of the raw materials currently used, so that a paste with good properties can be produced. As a result, the subsequent “3. lower process” is also performed well, and a secondary battery is manufactured.

  The range of application of the blending ratio P: S determined as described above is limited to the production of paste using the same kind of powder and solvent of graphite particles and other additives used for pre-kneading. However, in the actual paste production, an active material that is obtained by coating an amorphous film on the same kind of graphite particles as those used for pre-kneading is used. That is, it cannot be applied when the graphite particles, other additives, and solvent components are different, and the graphite particles, other additives, and solvent in that case need to be preliminarily kneaded and determined. Furthermore, it is preferable to re-determine the mixing ratio of the raw material graphite particles and other additives and solvents, even if they have the same specifications by the same manufacturer, if the raw material production lot changes.

  Next, examples of the present invention will be described together with comparative examples. In Examples and Comparative Examples, preliminary kneading for determining the blending ratio and subsequent main kneading were performed under the following conditions. In the following, items that do not distinguish between the embodiment and the comparative example are common to both.

[Preliminary kneading]
Kneading machine: Absorption amount measuring machine solvent used in Fig. 1: Water powder component Active material component: Natural graphite (before coating of amorphous film) "Example"
Natural graphite (after coating with amorphous film) “Comparative example”
Thickener: Carboxymethylcellulose sodium (CMC-Na)
Mixing ratio: 98.9% by weight of active material component + 1.01% by weight of thickener
Sample weight: 30 g
Measurement temperature: Room temperature 20 ° C. Expected solvent dropping speed: 6 cm ³ / min Stirrer rotation speed: 150 rpm

  Here, the “result” of the measured temperature means that the sample is not specially treated for the purpose of heating or cooling. However, there may be some temperature fluctuation due to frictional heat of stirring or heat of vaporization of the solvent.

  As the natural graphite (Example) before coating the amorphous film described as the active material component in the column of pre-kneading, those having an average particle diameter of 10 to 15 μm are used. Natural graphite having an average particle diameter of 10 to 15 μm is used for natural graphite after coating with an amorphous film (comparative example) before coating with the amorphous film. In addition, as will be described in detail later, the natural graphite particles after the coating of the amorphous film are actually partly agglomerated. Further, the natural graphite after the coating of the amorphous film is the same as the active material used for the main kneading described later.

  As a result of the preliminary kneading under the above conditions, the results shown in FIG. 3 were obtained. In the graph of FIG. 3, the vertical axis represents the kneading torque and the horizontal axis represents the solid content. First, in an example using natural graphite coated with an amorphous film as a comparative example as an active material component, the peak value T1 of the kneading torque is obtained when the solid content is 59.9% by weight. On the other hand, in the example using natural graphite before coating of the amorphous film as an active material component, the peak value T2 of the kneading torque is obtained when the solid content is 62.9% by weight. ing.

  As a result, when natural graphite coated with an amorphous film is used, the blending ratio is determined so that the solid content is 59.9% by weight. On the other hand, when natural graphite before coating of the amorphous film is used, the blending ratio is determined so that the solid content is 62.9% by weight.

[Main kneading]
Kneading machine: Planetary mixer (capacity 1 liter)
Use solvent: Water powder component Active material: Natural graphite (after coating of amorphous film)
Thickener: As described in the pre-kneading column Binder: Styrene butadiene rubber (SBR)
Mixing ratio: active material 98% by weight + thickener 1% by weight + binder 1% by weight
Sample weight: 300 g (weight of active material and thickener)
Measurement temperature: Room temperature 20 ° C. Rough kneading Kneading Solid content: 62.9% by weight “Example”
59.9 wt% “Comparative Example”
Rotation speed: 50rpm
Kneading time: 30 minutes dilution and kneading Kneading speed: 50 rpm
Kneading time: 10 minutes Final solid content: 54% by weight

  That is, in this kneading, natural graphite after coating of an amorphous film is used as an active material in both the examples and the comparative examples. Also for this active material, natural graphite having an average particle size of 10 to 15 μm is used before coating the amorphous film. Then, first, rough kneading was performed at a blending ratio that resulted in the solid content determined in the preliminary kneading. The components of the powder used for rough kneading are only the active material and the thickener among those shown in the mixing ratio of the powder components in the main kneading column. Moreover, a little solvent was added to the paste after rough kneading, and dilution kneading was performed. Furthermore, the binder was added to the paste after the dilution kneading and final kneading was performed. These dilution kneading and final kneading are kneading for adjusting the final solid content and properties of the paste in accordance with the required specifications from the lower process. The mixing ratio in the main kneading column is the one after addition of the binder, but the mixing ratio when looking at the active material and the thickener is the mixing ratio shown in the preliminary kneading column. Same as ratio.

  Here, the final viscosity of the paste completed by all the above-mentioned kneading steps is shown in the graph of FIG. In FIG. 4, the vertical viscosity represents the final viscosity of the paste, and the horizontal axis represents the solid content ratio during rough kneading. The graph in FIG. 4 shows that a paste is completed using a powder component and a solvent component having a plurality of different mixing ratios, and the relationship between the solid content ratio during rough kneading and the final viscosity of the paste is approximated by a curve. It is a representation. The relationship includes the above-described examples and comparative examples. As can be seen from the graph of FIG. 4, the most preferable solid content ratio at the time of rough kneading is 62.2% by weight. If this is set to the target solid content ratio and the powder component and solvent component at the time of rough kneading are blended, the final viscosity of the finished paste will be within the proper range even if some deviation occurs in the blending. It is easy.

  Here, the solid content determined by pre-kneading using natural graphite after coating of the amorphous film is 59.9% by weight. That is, the difference from the optimum solid content of 62.2% by weight is as large as 2.3% by weight. Furthermore, as shown in FIG. 4, since the final viscosity of the paste completed with the solid content ratio at the time of rough kneading being 59.9% by weight is too high, it is not within the proper range. This is why the example using natural graphite after coating of the amorphous film in the pre-kneading was used as a comparative example. In contrast, the solid content determined by pre-kneading using natural graphite before coating with the amorphous film is 62.9% by weight. That is, the difference from the optimum solid content ratio of 62.2% by weight is as small as 0.7% by weight. Moreover, the final viscosity of the paste completed by the solid content rate is in an appropriate range. For this reason, an example in which natural graphite before coating of the amorphous film was used in the preliminary kneading was taken as an example.

  In the following, the reason why the paste having the proper viscosity is not manufactured in the comparative example and the paste having the proper viscosity is manufactured in the example will be described with reference to the graph of FIG. The graph of FIG. 5 represents the particle size distribution of natural graphite and active material. In FIG. 5, the vertical axis represents volume frequency and the horizontal axis represents particle size. In FIG. 5, what is attached to natural graphite is the particle size distribution of natural graphite before coating with an amorphous film serving as the core of the active material. On the other hand, what is attached to the active material is the particle size distribution of natural graphite after the coating of the amorphous film. For the active material, the particle size distribution before and after the main kneading is shown.

As shown in FIG. 5, the volume frequency of natural graphite and the volume frequency of the active material after the main kneading both show peaks when the particle diameter is approximately D1. Furthermore, it can be seen that the particle size distribution of natural graphite and the particle size distribution of the active material after this kneading are almost the same. On the other hand, the volume frequency of the active material before the main kneading shows a peak when the particle diameter is D2 larger than D1. From this, it can be seen that there are many active materials having a larger particle size than the active materials after the main kneading. As described above, the reason why the active material exhibits different particle size distributions before and after the main kneading can be considered as follows.

  As described above, the active material used in this embodiment is obtained by coating the surface of graphite particles with an amorphous film. In the process of manufacturing the active material, the graphite particles that originally existed individually are covered with an amorphous film, and a lump in which these particles adhere to each other is generated. A suitable secondary battery cannot be manufactured with the active material in a state where the lump is formed. Therefore, after the step of coating the graphite particles with an amorphous film, a crushing treatment is performed to loosen the lump. The material after this crushing treatment is the active material used in this embodiment. That is, the active material before the main kneading shown in FIG.

  However, it seems that this crushing process was not sufficient. In other words, in the finished active material, a part of the lump remains undisintegrated even in the crushing process. Such a lump of active material is not loosened by pre-kneading. However, in the main kneading in which a plurality of kneading is performed for a long time, it is loosened and separated into active material particles. For this reason, it is considered that many active materials before the main kneading have a larger particle size than the active material after the main kneading. It is difficult to perform a crushing process that separates all lumps into active material particles. This is because applying the crushing treatment for a long time greatly reduces the productivity of the active material. Further, in an active material that has been excessively crushed, the amorphous film is peeled off from the graphite particles.

  In the comparative example, natural graphite coated with an amorphous film as an active material is used for both pre-kneading and main kneading. In other words, preliminary kneading is performed using the active material in which lumps remain. However, during the main kneading, the remaining lump of active material is separated into its particles. That is, in the comparative example, the mixing ratio of the main kneading is determined by pre-kneading the powder component having characteristics different from the powder component during the main kneading. Therefore, a paste having an appropriate viscosity cannot be produced.

  On the other hand, in the examples, natural graphite before coating with an amorphous film is used for preliminary kneading, and natural graphite after coating with an amorphous film as an active material is used for main kneading. That is, different powders are used for the preliminary kneading and the main kneading. However, as described above with reference to FIG. 5, the particle size distribution of the natural graphite before coating with the amorphous film is substantially the same as the particle size distribution of the active material after the main kneading. For this reason, in the examples, powder components having substantially the same characteristics are used in both the preliminary kneading and the main kneading. Therefore, a paste having an appropriate viscosity is manufactured.

  Then, using the final paste for the negative electrode obtained in the example, a secondary battery is manufactured by “3. Lower steps (coating, winding, storing, etc.)”. That is, the negative electrode paste is prepared by applying and drying the negative electrode paste onto the negative electrode current collector foil. In this application / drying stage, the quality of the paste has a great influence on the process, but this embodiment is good. This is because a paste having good properties is obtained as described above. A negative electrode mixture layer is formed on the negative electrode plate. Further, the obtained negative electrode plate together with the positive electrode plate is laminated by winding or flattening with a separator sandwiched between them to form an electrode body, and the secondary battery is obtained by storing this electrode body in a battery case. Manufactured. As the positive electrode plate and the separator, those conventionally used may be used.

Here, the present invention is particularly significant when the average particle diameter (D50) of the active material used is 20 μm or less. The average particle size here is not the average particle size including the active material in a lump state, but the average particle size of the particles of the active material that are completely separated. That is, it is considered that the average particle diameter is 20 μm or less by combining the size of graphite particles serving as a nucleus and the thickness of the amorphous film covering the core. And when manufacturing a paste using the active material whose average particle diameter is 20 micrometers or less, the solid content rate determined by the preliminary kneading along said comparative example will remove | deviate greatly from the optimal solid content rate. . For this reason, a paste with an appropriate viscosity cannot be produced. However, in the preliminary kneading according to the above-described embodiment, the solid content rate is determined to be close to the optimum solid content rate. Therefore, a paste having an appropriate viscosity can be produced by performing the main kneading based on the solid content rate.

  As described above in detail, according to the present embodiment, when the electrode mixture paste is manufactured by kneading the powder component and the solvent component, the blending ratio is first determined by preliminary kneading. In the electrode mixture paste, an active material in which the surface of graphite particles is coated with an amorphous film is used. For this reason, in the pre-kneading, among the powder components of the main kneading, a powder component in which the active material is replaced with graphite particles before coating the amorphous film serving as the core is used. And this kneading | mixing is performed by the compounding ratio determined by preliminary kneading | mixing, and the paste of a favorable property is obtained. For this reason, the lower process is satisfactorily performed and a high-quality secondary battery is obtained.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, the kneading machine itself is not limited to the above-mentioned one, and another type may be used. Moreover, various materials such as thickeners and binders as additives are merely examples.

DESCRIPTION OF SYMBOLS 1 Absorption amount measuring machine 2 Stirring container 3 Stirrer 4 Injection nozzle 5 Funnel 6 Powder 7 Solvent

Claims (3)

A powder component and a solvent component of an electrode mixture layer of a secondary battery are kneaded to produce an electrode mixture paste, and an electrode plate having an electrode mixture layer formed on the basis of the electrode mixture paste is used. In a secondary battery manufacturing method for manufacturing a secondary battery,
The powder component used when preparing the electrode mixture paste includes a powder of an electrode active material in which graphite particles are used as a core and the surface is coated with amorphous carbon.
Including powder of graphite particles before coating with amorphous carbon in the same proportion as the proportion of electrode active material powder in the powder components used when preparing electrode mixture paste, other components are electrode mixture paste creation The solvent of the same component as the solvent component used at the time of preparing the electrode mixture paste is injected into the powder having the same component as the powder component used at the time while measuring the liquid absorption, and the powder is injected while measuring the kneading torque. Pre-kneading with the solvent,
The powder component of the electrode mixture paste at a mixing ratio equal to the ratio of the amount of the powder component at the start of the pre-kneading and the cumulative supply amount of the solvent when the kneading torque shows the maximum value during the pre-kneading. A method for producing a secondary battery, characterized in that the electrode mixture paste is produced by main kneading in which a solvent component is mixed and kneaded. In the manufacturing method of the secondary battery according to claim 1,
The method for producing a secondary battery, wherein the electrode active material has an average particle size of 20 μm or less. In the manufacturing method of the secondary battery according to claim 1 or 2,
The present kneading will continue kneading for mixing the powder component and the solvent component of the composite electrode material paste in the mixing ratio, adjusted kneading to adjust the mixing ratio of the composite electrode material paste required specifications from the lower step A method for producing a secondary battery.

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