TW202224240A - Method for producing slurry for negative electrode, and slurry for negative electrode - Google Patents

Abstract

To provide a method for producing a slurry which is for a negative electrode and contains an alloy-based material or a hydrogen storage alloy, an aqueous binder, and water, and from which a uniform negative electrode can be obtained by suppressing the generation of a hydrogen gas. [Solution] This method for producing a slurry, which is for a negative electrode and which contains, as solid contents, an alloy-based material or a hydrogen storage alloy and an aqueous binder, and contains water as a dispersion medium, comprises a step for dissolving an acidic solute in the dispersion medium.

Description

The manufacturing method of the slurry for negative electrodes, and the slurry for negative electrodes

The present invention relates to a method for producing a slurry for negative electrodes and a slurry for negative electrodes used for negative electrodes of batteries (non-aqueous electrolyte secondary batteries or alkaline hydrogen batteries). Moreover, this invention relates to the manufacturing method of the negative electrode using this slurry for negative electrodes, the manufacturing method of a battery, and the manufacturing apparatus of a negative electrode, a battery, and the slurry for negative electrodes.

It is known that the positive electrode and the negative electrode of a battery are usually produced by mixing an active material with a binder and the like to form a slurry, applying it to a current collector, drying it, and adjusting the pressure with a roll press.

In recent years, a non-aqueous electrolyte secondary battery, an alkaline hydrogen battery, or the like has been circulated as a power storage device or a power generation device. Among them, in a typical lithium ion battery of a non-aqueous electrolyte secondary battery, an alloy-based material such as silicon (Si) or tin (Sn) is attracting attention as an active material for a negative electrode. For example, in the case of Si, when the alloy composition when fully charged is estimated as Li _4.4 Si, the theoretical capacity is 4199 mAh/g per unit mass and 9784 mAh/cc per unit volume, which is related to graphite (per unit The mass is 372 mAh/g, and the capacity per unit area is 855 mAh/cc) about 10 times higher. In addition, it is higher than the capacity of metal lithium (2062 mAh/cc) per volume. Therefore, alloy-based materials are ideal negative electrode materials for increasing the capacity of batteries. In addition, it is known from Non-Patent Document 1 that a battery using a Si-based material for the negative electrode is good in safety, output characteristics, and high-temperature durability due to internal short-circuit.

Furthermore, in the present application, alloy-based material refers to a general term for metal elements or their compounds that can react with cations (carriers) responsible for electrical conduction to be alloyed during charging. For example, if it is a lithium ion battery, the carrier is lithium ion; if it is a sodium ion battery, the carrier is sodium ion; if it is a potassium ion battery, the carrier is potassium ion; if it is a magnesium ion battery, the carrier is It is magnesium ion; if it is a calcium ion battery, the carrier is calcium ion; if it is an aluminum ion battery, the carrier is aluminum ion.

However, Si-based materials such as Si, silicon monoxide (SiO), and Si-Ti alloys undergo large volume changes during charging (alloying reactions). For example, the volume of Si changes about 4 times when fully charged, so material pulverization or electrode structure damage is likely to occur. As a result, the conductive network of the Si negative electrode was destroyed, showing severe cycle degradation.

As one of the methods for prolonging the life of a negative electrode using a Si-based material, control of the particle size of the Si-based material is being studied (Non-Patent Document 1). According to this document, in a Si negative electrode using a polyimide (PI)-based binder, stable cycle characteristics can be obtained by controlling the particle size to 3 μm or less.

In addition, binders are used to bind active materials, conductive aids, etc. to the current collector, and can be roughly classified into water-based (aqueous) and organic solvent-based (non-aqueous) according to the type of solvent used. For example, polyvinylidene fluoride (PVdF), which is a typical binder for electrodes, is insoluble in water, so an organic solvent such as N-methyl-2-pyrrolidone (NMP) is used in the step of preparing the electrode slurry.

However, when a Si-based material is used as the negative electrode material, the conventional PVdF binder will have a large volume change with charging and discharging, and stable cycle characteristics cannot be obtained. Therefore, high-adhesion adhesives such as acrylic-based (Patent Documents 1 and 2), polyimide-based (Patent Documents 2 and 3), and inorganic-based (Patent Documents 3 and 4) have been studied. In addition, recently, considering the impact of NMP on the environment and the human body, water-based adhesives with less environmental load have also attracted attention, but Si-based materials react with water to generate hydrogen, so the use of water-based adhesives extremely difficult.

That is, if a water-based binder is used for a Si-based material having a small particle size, water is decomposed to generate hydrogen gas, so that it is very difficult to handle, and a uniform electrode cannot be obtained. In addition, when hydrogen gas is generated, an oxide film which reduces the capacity and increases the resistance is formed on the surface of the Si particles (refer to the following formula 1). For example, Patent Document 7 discloses a technique for producing hydrogen gas by bringing a silicon fine powder having an average particle diameter of 2 μm or less into contact with water. As such, Si-based materials are generally used for generating hydrogen by reacting with water. Si+2H ₂ O→SiO ₂ +2H ₂ ↑ Formula 1

In addition, the smaller the particle size of the silicon powder used, the larger the surface area of the total amount, so there is a tendency that the amount of hydrogen gas generated per unit silicon weight and per unit time increases. In addition, the higher the pH value or the higher the temperature of water, the faster the hydrogen gas generation rate tends to be.

For this reason, when a Si-based material is used as the active material of the negative electrode, it is extremely difficult to apply the Si-based material to a slurry containing water such as a water-based binder. This problem is common to alloy-based materials other than silicon.

In addition, in an alkaline hydrogen battery, a hydrogen storage alloy such as A ₂ B series, AB series, AB ₂ series, or AB ₅ series is used as the negative electrode. Alkaline hydrogen battery is a general term for battery systems that use an alkaline aqueous solution as an electrolyte and a hydrogen storage alloy as a negative electrode, such as nickel-hydrogen (Ni-MH) batteries and alkaline fuel cells (AFC).

In the case of using a hydrogen storage alloy as the negative electrode of an alkaline hydrogen battery, as with the above-mentioned Si-based material, if a water-based binder is applied to the hydrogen storage alloy with a small particle size, water is decomposed to generate hydrogen gas, which is simultaneously stored in the hydrogen storage alloy. An oxide film (including hydroxide) is formed on the surface of the hydrogen alloy particles. When the hydrogen absorbing alloy is oxidized, the amount of hydrogen occluded in the alloy decreases, and the electrical conductivity of the hydrogen absorbing alloy decreases, resulting in problems such as increase in impedance.

Therefore, in order to obtain the original battery characteristics, it is necessary to activate and remove the oxide film. From the viewpoint of cost reduction, the step of manufacturing the NiMH battery and performing the activation (activation treatment) before shipment requires a shortened time. Usually, the activation treatment is repeated dozens of cycles of charge and discharge, or repeated slow charge such as 0.1 C rate to 0.2 C rate for several times - the same slow discharge (0.1 C rate to 0.2 C rate can be performed in 5 ~ The amount of current to discharge or charge the total capacity of the battery within 10 hours).

However, since this activation treatment requires more than one day, it is required to shorten the activation treatment time. In addition, if the hydrogen storage alloy is repeatedly charged and discharged, it is easily pulverized or detached from the current collector. Therefore, in order to reduce the number of charge and discharge cycles as much as possible, Patent Document 11 discloses hydrochloric acid treatment as a surface modification treatment method in which an acid treatment is performed on a hydrogen storage alloy to remove the oxide film existing on the surface of the alloy particles. .

In addition, as a method of suppressing the formation of an oxide film, acid treatment using phosphoric acid or hydrofluoric acid is known (Patent Document 12).

Among them, regarding the hydrofluoric acid treatment, taking the hydrogen storage alloy of LaNi ₅ as an example, the oxygen of the oxide (La ₂ O ₃ ) existing on the surface is first removed, and a LaF ₃ layer is formed on the surface of LaNi ₅ (refer to the following formula 2 ). La ₂ O ₃ +6H ⁺ +6F ⁻ →2LaF ₃ +3H ₂ O Equation 2 However, after the reaction of Equation 2, a fluorination reaction proceeds, and thus hydrogen gas is generated (see Equation 3 below). 2La ³⁺ +6F ^- +6H ⁺ +6e ^- → 2LaF ₃ +3H ₂ ↑ Formula 3 LaF ₃ and other fluoride layers have hydrogen permeability, so they have excellent initial activity, but there are problems that electrical conductivity and thermal conductivity decrease, and discharge capacity decreases .

In addition, in the surface modification treatment by acid treatment, a water washing step for removing the treatment solution adhering to the hydrogen storage alloy must be provided as a subsequent step, which may lead to an increase in manufacturing cost. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Publication No. 2014/207967 [Patent Document 2] Japanese Publication No. 2014/014006 [Patent Document 3] Japanese Patent Laid-Open No. 2009-076373 [Patent Document 4] Japanese Patent Laid-Open No. 2017-73363 [Patent Document 5] Japanese Patent No. 6149147 [Patent Document 6] Japanese Patent Laid-Open No. 2018-063912 [Patent Document 7] Japanese Patent Application Laid-Open No. 4-59601 [Patent Document 8] Japanese Patent Laid-Open No. 2004-115349 [Patent Document 9] Japanese Publication No. 2017/138192 [Patent Document 10] Japanese Publication No. 2017/138193 [Patent Document 11] Japanese Patent Application Laid-Open No. 05-225975 [Patent Document 12] Japanese Patent Application Laid-Open No. 03-152868 [Non-patent literature]

[Non-Patent Document 1] Takashi Mukai: "Lithium-ion batteries - Development of performance improvement and LiB industry trends for automotive applications -" pp. 38-39, Science & Technology (2019)

[The problem to be solved by the invention]

As described above, when an alloy-based material such as silicon, which is an ideal negative electrode active material for increasing the capacity of a battery, or a hydrogen storage alloy such as a LaNi ₅ -based alloy, is used as a slurry containing water such as a water-based binder with a small environmental load, Alloy-based materials or hydrogen storage alloys decompose water to generate hydrogen gas, so the operation is very difficult, and there is a problem that a uniform electrode cannot be obtained. In addition, since an oxide film is formed on the particle surface of the active material at the same time as hydrogen gas is generated, there is a problem that the capacity decreases and the resistance increases.

Therefore, the inventors have made intensive studies in view of the above-mentioned problems, and as a result, they have completed the present invention: when an alloy-based material or an active material of a hydrogen storage alloy is applied to a slurry containing water, the generation of hydrogen is also suppressed, and a uniform negative electrode can be obtained. . That is, the main object of the present invention is to provide a method for producing a slurry for a negative electrode, a slurry for a negative electrode, which, although an alloy-based material or an active material of a hydrogen storage alloy is applied to a slurry containing water, suppresses the formation of a surface of the active material. Oxidation, and suppressing the generation of hydrogen, a uniform negative electrode can be obtained. [Technical means to solve the problem]

In order to achieve the above-mentioned object, a method for producing a slurry for a negative electrode according to an aspect of the present invention is a method for producing a slurry for a negative electrode containing an active material as a solid component, an aqueous binder, and a dispersion medium containing water. In the above-mentioned active material-based alloy-based material or hydrogen storage alloy, the production method includes the steps of: mixing the above-mentioned active material, the above-mentioned water-based binder and the above-mentioned dispersion medium to prepare a slurry; and making the pH of the above-mentioned slurry. Step 6.9 is not reached.

According to this structure, by making the slurry containing water acidic, the decomposition of water can be suppressed, and the generation of hydrogen gas can be suppressed. By using this slurry for negative electrodes, a uniform negative electrode in which voids due to hydrogen gas and unevenness due to air bubbles are suppressed can be obtained. In addition, by suppressing the generation of hydrogen, the oxidation of alloy materials or hydrogen storage alloys can be suppressed, so the oxide film formed on the surface is also thinner than the conventional oxide film, and the resistance caused by the oxide film can be suppressed compared with the conventional one. Moreover, regarding the process of making the pH of the said slurry less than 6.9, the following method of dissolving an acidic solute, or the method of acidifying a slurry is considered, for example.

Moreover, in this manufacturing method of the slurry for negative electrodes, the process of making the pH of the said slurry less than 6.9 is a process of making an acidic solute dissolve in the said dispersion medium. Here, the step of dissolving the acidic solute in the dispersion medium includes the step of dissolving the acidic solute in the dispersion medium in advance, and also includes mixing the active material, the water-based binder and the dispersion medium to form a slurry, The step of dissolving the acidic solute in the slurry. By dissolving the acidic solute in the slurry, the acidic solute can be dissolved in the dispersion medium and the slurry is made acidic.

Further, the step of dissolving the acidic solute in the dispersion medium is preferably a step of dissolving carbon dioxide as the acidic solute in the dispersion medium. The reason for this is that, by using carbon dioxide as an acidic solute, it is easy to handle and to obtain. In addition, carbon dioxide has the advantage that it does not affect the solid ratio of the slurry and does not contain an acidic solute in the electrode. Carbon dioxide may be any of solid, liquid, and gas, and is preferably a gas in terms of good handleability and availability. Examples of other acidic solutes include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid; and organic acids such as acetic acid, citric acid, malic acid, lactic acid, succinic acid, tartaric acid, maleic acid, sulfamic acid, and gluconic acid. However, when a current collector with insufficient oxidation resistance (such as an Al current collector) is used, or when an active material with insufficient oxidation resistance is used, hydrochloric acid, sulfuric acid, and nitric acid react to corrode the current collector or active substance. Therefore, carbon dioxide, phosphate, or organic acid is preferable. In addition, these can also be used as a mixed acid.

According to this configuration, by dissolving carbon dioxide in the water as the dispersion medium, the water becomes acidic, so that the decomposition of water can be suppressed, and the generation of hydrogen gas can be suppressed. By using this slurry for negative electrodes, a uniform negative electrode in which voids due to hydrogen gas and unevenness due to air bubbles are suppressed can be obtained. In addition, by suppressing the generation of hydrogen, the oxidation of alloy materials or hydrogen storage alloys can be suppressed, so the oxide film formed on the surface is also thinner than the conventional oxide film, and the resistance caused by the oxide film can be suppressed compared with the conventional one.

In addition, the water used as a dispersion medium includes not only water contained as a dispersion medium for dispersing solid content, but also water contained in a liquid aqueous binder. In addition, in the step of dissolving carbon dioxide in the dispersion medium, carbon dioxide can be dissolved in water as a dispersion medium in the slurry by introducing carbon dioxide into a slurry in which various materials such as a solid content and a dispersion medium are mixed. It can also be performed by introducing carbon dioxide into a dispersion medium containing water in advance. In addition, the dispersion medium should just be water as a main component, and a part of a water-soluble organic solvent may be melt|dissolved.

In addition, the inventors have invented the use of carbon dioxide in the slurry for positive electrodes of non-aqueous electrolyte secondary batteries (for example, Patent Documents 9 and 10). These inventions remove the remaining carbon dioxide after neutralizing the alkaline components by introducing carbon dioxide into the slurry containing the alkali metal composite oxide. That is, the biggest purpose is to prevent corrosion of the current collector by neutralizing the slurry for positive electrodes with carbon dioxide. In addition, by removing the inorganic carbon dissolved in the slurry after neutralization, in the process of drying the positive electrode slurry after coating the current collector, the generation of carbon dioxide bubbles and the like can be prevented.

On the other hand, the present invention is an invention of dissolving carbon dioxide in a dispersion medium by using an acidic solute such as carbon dioxide for the negative electrode slurry of a battery. Although the present invention uses an alloy-based material as a solid component or an active material of a hydrogen storage alloy, a binder, and water as a dispersion medium, carbon dioxide is dissolved in the dispersion medium by introducing carbon dioxide, etc. The material or hydrogen storage alloy reacts with water to produce hydrogen. That is, the present invention is an invention of suppressing the generation of hydrogen gas from the slurry and forming a negative electrode with a thin oxide film, although an alloy-based material, a hydrogen storage alloy and water are used, and the slurry is not neutralized as in the above-mentioned invention of the slurry for positive electrode. , nor is it necessary to constitute degassing.

Moreover, the manufacturing method of this slurry for negative electrodes may further include the process of generating a cavity (cavitation) in the said slurry, and removing the carbon dioxide dissolved in this slurry. By removing excess carbon dioxide by using holes, it is possible to prevent voids caused by the generation of excess carbon dioxide or unevenness caused by air bubbles at the stage of coating the negative electrode slurry on the current collector and drying it.

Moreover, in this manufacturing method of the slurry for negative electrodes, the process of dissolving carbon dioxide in the said dispersion medium is a process of supplying the carbon dioxide of more than 0.10 MPa and 10 MPa or less to the said slurry. According to this configuration, when carbon dioxide is introduced by the pressurization method, carbon dioxide can be efficiently dissolved in the dispersion medium by introducing carbon dioxide at a pressure higher than atmospheric pressure.

On the other hand, in the manufacturing method of this slurry for negative electrodes, the step of dissolving carbon dioxide in the dispersion medium may be a step of supplying carbon dioxide of 0.10 MPa or less to the slurry. This configuration is a case of using the cavitation method when introducing carbon dioxide. The cavitation method is different from other methods such as bubble method, carbonate decomposition method and pressurization method. Carbon dioxide is introduced under the pressure of not more than 0.10 MPa. The reason for this is that when the pressure exceeds 0.10 MPa, it becomes difficult to generate voids.

Moreover, in this manufacturing method of the slurry for negative electrodes, the median particle diameter (D50) of the said alloy-type material or the said hydrogen storage alloy is 5 nm or more and 3 micrometers or less. According to this configuration, by setting the median particle diameter (D50) of the alloy-based material or the hydrogen storage alloy to be 3 μm or less, the generation of hydrogen gas can be suppressed, and the high capacity and long life of the battery can be achieved at the same time. Furthermore, by setting the median particle diameter (D50) of the alloy-based material or hydrogen storage alloy to be 5 nm or more, the electrode can be formed when the total amount of the active material, the water-based binder, and the conductive material is 100% by mass. The required amount of adhesive is below 25% by mass.

Here, the median particle diameter (D50) means the particle diameter when the cumulative frequency of the volume-based volume conversion is 50% using the laser diffraction scattering particle size distribution measurement method, and the same applies hereinafter. As the measuring device, "LA-960" manufactured by HORIBA or the like can be used.

Moreover, in the manufacturing method of this slurry for negative electrodes, the process of making the pH of the said slurry less than 6.9 may be the process of acidifying this slurry. That is, by acidifying the slurry, the pH of the slurry is made acidic not to reach 6.9.

Moreover, in this manufacturing method of the slurry for negative electrodes, the process of making the pH of the said slurry less than 6.9 is a process of making pH 3.4 or more and less than 6.9. As described above, as the pH value is higher, the generation of hydrogen gas increases. Therefore, the generation of hydrogen gas can be suppressed by making the slurry acidity less than 6.9. Moreover, by making pH 3.4 or more, corrosion of a collector or an active material is suppressed by the strong acid whose pH value is less than 3.4.

Here, pH means a hydrogen ion index, which means a standard indicating whether the liquid is acidic or basic, and the same applies hereinafter. When the pH value is less than 7, it is acidic, and when the pH value is greater than 7, it is alkaline. As for the pH measurement method, a pH measurement device using a glass electrode can be used, but in the vicinity of pH 7, precise measurement may not be possible, so pH test paper is preferably used.

Moreover, in this manufacturing method of the slurry for negative electrodes, it is preferable that the said alloy-type material or the said hydrogen storage alloy is a Si-type material. According to this configuration, by using the Si-based material as the alloy-based material or the above-mentioned hydrogen storage alloy, it is possible to increase the capacity of the battery.

Moreover, in the manufacturing method of this slurry for negative electrodes, the said slurry for negative electrodes can be used for the negative electrode of a non-aqueous electrolyte secondary battery.

The manufacturing method of the negative electrode which concerns on one aspect of this invention is characterized by including the process of apply|coating or filling the current collector with the slurry for negative electrodes manufactured by the said manufacturing method of the slurry for negative electrodes.

A method of manufacturing a battery according to an aspect of the present invention is characterized by including the step of combining the negative electrode, the positive electrode, and the electrolyte manufactured by the above-described method for producing the negative electrode.

The slurry for a negative electrode according to one aspect of the present invention is characterized in that it contains an active material as a solid component, a water-based binder, and a dispersion medium containing water, and the above-mentioned active material is an alloy-based material or a hydrogen storage alloy, and the negative electrode is characterized in that: The pH of the slurry used did not reach 6.9.

Moreover, the pH of the slurry for negative electrodes is 3.4 or more and less than 6.9. As described above, if the pH value is less than 3.4, the current collector or the active material is corroded. On the other hand, when the pH value is 6.9 or more, hydrogen gas is generated and the oxide film on the particle surface of the active material tends to be thickened. Depending on the type or particle size of the active material used, and the temperature of the slurry, the thickness or density of the oxide film formed on the surface of the active material varies. There is no problem in charge and discharge characteristics, and the pH value is more preferably 3.6 or more and 6.6 or less, and more preferably 4.0 or more and 6.1 or less.

In addition, an acidic solute is dissolved in this slurry for negative electrodes. The acidic solute is preferably carbon dioxide.

Moreover, in this slurry for negative electrodes, an oxide film is formed on the particle surface of the above-mentioned alloy-based material or the above-mentioned hydrogen storage alloy. In addition, the oxide film is preferably 1 nm or more and 300 nm or less. If the oxide film is less than 1 nm, when the battery is charged and discharged, the solvent contained in the electrolyte is decomposed to generate gas. When the oxide film exceeds 300 nm, the oxide film is thick, so not only the impedance increases, but also the irreversible capacity of the battery increases, and the battery characteristics decrease. Furthermore, the adjustment of the thickness of the oxide film varies according to the type or particle size of the active material used, and the temperature of the slurry, and can be controlled by adjusting the pH value.

In addition, in the slurry for negative electrodes, the oxide film on the surface of the above-mentioned alloy-based material or the above-mentioned hydrogen storage alloy is thinner than the alloy-based slurry in the slurry for negative electrodes in which the water in which carbon dioxide is not dissolved is replaced by water in which carbon dioxide is not dissolved. Oxide film on the surface of particles of materials or hydrogen storage alloys”. Compared with the conventional case where carbon dioxide is not dissolved, the oxide film is thinner, so resistance can be suppressed and battery characteristics can be improved.

Moreover, in this slurry for negative electrodes, the median particle diameter (D50) of the above-mentioned alloy-based material or the above-mentioned hydrogen storage alloy is 5 nm or more and 3 μm or less. If the median particle size is less than 5 nm, the specific surface area of the active material is larger, and more binders are required for the electrode. On the other hand, when the median particle size exceeds 3 μm, the specific surface of the active material is small, so the reaction field of the electrode is small, and the input and output characteristics are poor, especially the Si-based material cannot maintain a stable capacity. For example, in the case of Si powder whose median particle diameter (D50) is 5 nm or more and 3 μm or less, the specific surface area is 2 m ² /g or more and 1000 m ² /g or less.

Moreover, in this slurry for negative electrodes, the above-mentioned alloy-based material or the above-mentioned hydrogen storage alloy-based Si-based material is used. According to this configuration, since the Si-based material is used as the active material, a thinner and lighter electrode can be provided.

Moreover, this slurry for negative electrodes is used for the negative electrode of a non-aqueous electrolyte secondary battery. According to this configuration, by using the Si-based material as the alloy-based material or the above-mentioned hydrogen storage alloy, it is possible to increase the capacity of the battery.

A negative electrode according to an aspect of the present invention is characterized by including a current collector and an active material layer in which the above-mentioned slurry for negative electrodes is cured on the current collector. According to this configuration, electrons can be moved to the active material via the current collector, and charge and discharge can be performed with low resistance.

An apparatus for producing a slurry for negative electrodes according to an aspect of the present invention disperses and mixes an alloy-based material or a hydrogen storage alloy as a solid component, a water-based binder, and a dispersion medium containing water in a dispersion-mixing section to produce a negative electrode. The slurry manufacturing apparatus is characterized by being provided with a hydrogen generation suppressing part for suppressing "hydrogen gas generated by the reaction of the above-mentioned alloy-based material or the above-mentioned hydrogen storage alloy and the above-mentioned water". According to this structure, the slurry for negative electrodes which suppresses the generation|occurence|production of hydrogen gas can be manufactured. Moreover, the said hydrogen generation suppression part has a carbon dioxide introduction part which introduce|transduces carbon dioxide into the dispersion medium or slurry containing water. [Effect of invention]

According to the production method of the slurry for negative electrodes of the present invention, by dissolving carbon dioxide in the water serving as the dispersion medium in the slurry, the generation of hydrogen gas from the slurry for negative electrodes using an alloy-based material or a hydrogen storage alloy can be suppressed.

Hereinafter, an embodiment of the manufacturing method of the slurry for negative electrodes of this invention is demonstrated based on drawing, but this invention is not limited to the following embodiment.

<1. Manufacturing method of slurry for negative electrodes> The method for producing a slurry for a negative electrode of the present embodiment is for producing a slurry for a negative electrode, the slurry for a negative electrode containing an alloy-based material or a hydrogen storage alloy as a solid content as an active material, a water-based binder, and a Water dispersion medium. Specifically, an alloy-based material or a hydrogen storage alloy as a powdery active material as a material of a slurry, a conductive aid, an aqueous binder, and a dispersion medium containing water are mixed, and the mixture is given The shearing force disperses and mixes the solid content in the mixed solution to produce a slurry. Then, carbon dioxide, which is an example of an acidic solute, is dissolved in water as the dispersion medium. The method of dissolving carbon dioxide in the dispersion medium is carried out, for example, by introducing carbon dioxide into the slurry or the dispersion medium.

In addition, carbon dioxide is hardly soluble in water under normal pressure. It is known from Henry's Law that the amount of carbon dioxide dissolved in a solvent is proportional to the pressure. That is, when carbon dioxide is dissolved in a solvent under a pressurized state, the concentration of inorganic carbon (carbon dioxide, carbonic acid, carbonate ions, and bicarbonate ions) in the solvent can be increased. In addition, the reaction speed is largely dependent on the concentration of the reactant and the ambient temperature, so the higher the concentration of the reactant and the ambient temperature, the faster the chemical reaction.

In addition, as a general method for dissolving carbon dioxide in a liquid, a bubble method, a carbonate decomposition method, a pressurization method, and the like are known. The bubble method is a method of dissolving carbon dioxide by passing carbon dioxide into the liquid in the form of bubbles. The finer the volume of the bubbles, the more efficiently carbon dioxide can be dissolved. The carbonate decomposition method is a method of decomposing carbonate with an acid to dissolve carbon dioxide, but it is not suitable because an acid is required. The pressurization method is a method of dissolving carbon dioxide in a liquid under pressure, and this embodiment uses the pressurization method as an example. The pressurization method increases the pressure according to Henry's law, and can obtain water containing a high concentration of dissolved carbon dioxide (ie carbonated water).

In this embodiment, a method of introducing carbon dioxide into the device system using the cavitation effect can be used as another example. The introduced carbon dioxide expands and contracts violently at the interface with water due to the cavitation effect, so carbon dioxide is easily dissolved in water.

Furthermore, in the pressurization method, the introduction pressure of carbon dioxide is greater than 0.10 MPa in absolute pressure, preferably 0.2 MPa or more, and more preferably 0.3 MPa or more. In addition, if the pressure exceeds 100 MPa, not only will the scale of the production equipment increase, but also the residual amount of dissolved carbon dioxide in the slurry will increase, making it difficult to perform subsequent degassing treatment. Therefore, the upper limit of the pressure is 100 MPa or less. It is preferably 50 MPa or less, and more preferably 10 MPa or less.

In the cavitation method, the introduction pressure of carbon dioxide is preferably 0.10 MPa or less. That is, the cavitation method is characterized in that the introduction pressure of carbon dioxide is lower than that of general methods such as the bubble method, the carbonate decomposition method, and the pressurization method. The reason for this is that when the pressure exceeds 0.1 MPa, it becomes difficult to generate voids.

In addition, carbon dioxide may be introduced into a slurry in which each slurry material such as a solid content or a dispersion medium is dispersed and mixed, or may be introduced into the dispersion medium in advance. In either case, carbon dioxide was dissolved in water as a dispersion medium to form carbonated water.

In addition, when a step of mixing the solid content of the slurry is included by generating cavities in the slurry, the dissolved carbon dioxide may be vaporized and dissociated by negative pressure, and the dispersion efficiency may decrease. Therefore, carbon dioxide is preferably introduced into the slurry during or after the mixing of the solid content of the slurry.

Moreover, regarding the introduction amount of carbon dioxide, in the present embodiment, the pH value of the slurry is introduced in such an amount that the slurry becomes acidic so that the pH value of the slurry is 3.4 or more and less than 6.9.

Moreover, since excess carbon dioxide may be dissolved in the slurry into which carbon dioxide has been introduced, degassing can be performed. The reason for this is that when the dissolved carbon dioxide is close to the saturated amount, if the slurry is applied to the current collector without degassing, the carbon dioxide dissolved in the slurry may generate carbon dioxide bubbles during the drying step. . In this case, voids may be formed due to the generated carbon dioxide, or uneven coating or electrode peeling or peeling may be caused due to air bubbles.

The dispersion and mixing method of the solid content of the slurry can be carried out by using an existing mixing method, and it is preferably dispersed and mixed by generating cavities (partial boiling). In addition, by adopting the method of dispersing and mixing by generating cavities, the carbon dioxide dissolved in the slurry can also be removed by the same apparatus. That is, it can be used as a dispersion mixing device and a degassing device.

As described above, the slurry of the present embodiment contains an alloy-based material or a hydrogen storage alloy as an active material as a solid content, and a water-based binder, and a conductive aid is added as necessary. Moreover, water is contained as a dispersion medium.

The active material is not particularly limited, as long as it is an alloy-based material or a hydrogen storage alloy. For example, when the battery is a lithium ion battery, materials such as Si, Sn, Al, Ge, Sb, Bi, Pb, and Ag are exemplified. Also, these may be elements, oxides, alloys with other transition metals. Here, the simple substance of the alloy-based material refers to a crystalline or amorphous material having a purity of 95 mass % or more of one element selected from Si, Sn, Al, Ge, Sb, Bi, Pb, and Ag. Alloys with other transition metals mean Si-M alloys composed of one element selected from Si, Sn, Al, Ge, Sb, Bi, Pb, Ag and other transition elements M, for example, M can include: Mg , La, Ti, Y, Cr, Cu, Ni, Zr, V, Nb, Mo, etc., and can also be completely solid solution alloys, eutectic alloys, hypoeutectic alloys, hypereutectic alloys, and peritectic alloys.

Oxide means an oxide composed of one element selected from Si, Sn, Al, Ge, Sb, Bi, Pb, and Ag and oxygen, or an oxide composed of one element selected from Si, Sn, Al, Ge, Sb, Bi , Pb, Ag any one of the simple substance and its oxide complex. For example, in the case of Si oxide, the element ratio of Si to O may be 1 and O should be 1.7 or less with respect to Si. Among them, silicon simple substance is preferable because the following oxide film can be formed to be 1 nm or more and 200 nm or less.

Moreover, these may be used individually by 1 type, and may use 2 or more types together, and may use together with a well-known material other than an alloy system. Furthermore, the element ratios of the above-mentioned active materials may be slightly different. In addition, in the case of a sodium secondary battery, it is a sodium composite oxide, that is, the lithium of the above-mentioned alkali metal element can be replaced by sodium; in the case of a potassium secondary battery, the lithium of the above-mentioned alkali metal element can be replaced by potassium . In addition, in the case of an alkaline hydrogen battery, a hydrogen storage alloy can be used instead of an alloy-based material.

The hydrogen storage alloy is not particularly limited, as long as it is a material for nickel-metal hydride batteries or alkaline fuel cells, and examples thereof include materials such as A ₂ B series, AB series, AB ₂ series, and AB ₅ series. Specifically, examples of the A ₂ B system include Mg ₂ Ni, Mg ₂ Cu, etc.; examples of the AB system include ZrNi, FeTi, TiCo, ZrCo, CaSi, and the like; and examples of the AB ₂ system include: TrCr ₂ , Si _1.5 Ca, TiMn _1.5 , ZrCr ₂ , ZrMn ₂ , ZrV ₂ , CaNi ₂ , etc.; as AB ₅ series, can be listed: LaNi ₅ , CaNi ₅ , MnNi ₅ etc.; Some elements are replaced with other elements.

The shape of the above-mentioned active material is not particularly limited, and can be spherical, elliptical, polygonal, ribbon, fibrous, flake, annular, or hollow powder, which can be single particles or Granules.

In addition, from the viewpoint that the electrode has excellent cycle characteristics and high input-output characteristics, the median particle size (D50) of the active material (alloy-based material or hydrogen storage alloy) is preferably 5 nm or more and 3 μm the following.

In addition, from the viewpoint that the electrode has excellent cycle characteristics and high input-output characteristics can be obtained, the specific surface area of the active material (alloy-based material or hydrogen storage alloy) is preferably 2 m ² /g or more and 1000 m ² / g or less.

The water-based binder may be a commonly used one for binding an active material to an active material, an active material to a conductive aid, an active material to a current collector, and a conductive aid to a current collector. For example, fluorine-based resin (PTFE, PVdF, etc.), styrene butadiene resin (SBR), natural rubber, acrylic resin, acrylic resin, polyvinyl alcohol, urethane, polyimide, polypropylene can be used , polyethylene, polyaramide, polyamide acid, lithium silicate, sodium silicate, potassium silicate, ammonium silicate, aluminum phosphate, magnesium phosphate, aluminum borate, etc. Two or more types can be used in combination.

These can be classified into water-based and organic solvent-based according to the type of solvent or dispersion medium, and are limited to water-based binders in the present invention. That is, as long as the main component of the solvent or dispersion medium is water, it may be a dispersion type or a solution type. Here, the dispersion-type water-based adhesive is an adhesive used by dispersing adhesive particles of 10 nm to 900 nm in water, such as fluorine-based resin or SBR, acrylic resin, acrylic resin, urethane, polyimide and other adhesives. Solution-type water-based adhesives are adhesives used to dissolve or swell the adhesive in water, such as PVA-based or polyamide acid, lithium silicate, sodium silicate, potassium silicate, ammonium silicate, aluminum phosphate, phosphoric acid Magnesium, aluminum borate, etc.

Moreover, the said slurry may use a thickener together as a viscosity modifier. As the tackifier, for example, methyl cellulose, ethyl cellulose, ethyl methyl cellulose, carboxymethyl cellulose (CMC) salts (eg CMC-Na, CMC-ammonium), hemicellulose, microcellulose can be used. Crystalline cellulose, cellulose nanocrystals, cellulose nanofibers, Sanxian gum, acrylic acid-polyvinyl alcohol copolymer, acrylic acid-polyvinyl alcohol-methyl methacrylate copolymer, alginate (such as lithium alginate) , sodium alginate, potassium alginate, ammonium alginate, alginate) and other commonly used materials, these can be used alone or in combination of two or more.

However, the pH values of the water-based adhesives and tackifiers exemplified above are often 6.9 or more. In addition, in order to improve storage characteristics (dispersion stability, antiseptic property, etc.), there are cases where additives that increase pH value are contained, and the pH value of water-based adhesives or tackifiers containing such additives is 6.9 or more.

For example, Figure 8 shows the pH of various aqueous solutions or representative aqueous binders. The pH of the commercially available SBR dispersion is 7.2 to 8.5, the pH of the acrylic resin dispersion is 7.4 to 9.0, the pH of the acrylic-polyvinyl alcohol copolymer aqueous solution is 7.4 to 9.0, and the pH of the PTFE dispersion is 9 to 12. The pH of the CMC-Na aqueous solution is 7.0-8.0, and the pH of the sodium alginate aqueous solution is 7.0-8.0. Therefore, if only the alloy-based material or the hydrogen storage alloy is mixed to form a slurry, a large amount of hydrogen gas is generated, and a thick oxide film grows on the surface of the alloy-based material or the hydrogen storage alloy particle.

When producing a slurry, it is preferable to apply to the active material dispersion containing carbon dioxide in the above-mentioned water-based adhesive or the above-mentioned thickener, or to dissolve carbonic acid beforehand. Specifically, it is preferable to use it by adjusting the dissolved amount of carbon dioxide so that the pH value of the slurry or the water-based binder is 4.0 or more and less than 6.9.

The conductive auxiliary agent is not particularly limited, and examples include metals, carbon materials, conductive polymers, and conductive glass. Among them, metal materials or carbon materials are preferred. Specifically, metal materials include copper, nickel, and cobalt. , platinum, palladium, titanium, etc.; carbon materials include: acetylene black, Ketjen Black (KB), vapor grown carbon fiber (VGCF), carbon nanotube (CNT), graphite, hard carbon, soft carbon, Furnace black, lamp black, activated carbon, graphene, glassy carbon, carbon nanohorn, etc. These can be used 1 type or 2 or more types.

In the active material layer of the negative electrode, for example, when the total amount of the active material, the water-based binder, and the conductive material is 100% by mass, the active material is preferably 60 to 99% by mass and the water-based binder is 0.1 to 25% by mass. %, and the conductive substance is 0 to 10% by mass. More preferably, the amount of the electrode active material is 80 to 95% by mass, the amount of the binder is 0.5 to 15% by mass, and the amount of the conductive material is 0.1 to 10% by mass. Conductive additives can be added as needed. With the composition of the active material layer of the negative electrode, sufficient adhesive force can be obtained, and it can function as an electrode of a battery.

Moreover, the slurry for negative electrodes obtained by the manufacturing method of the slurry for negative electrodes of this embodiment can be used to manufacture the negative electrode of a battery, and this negative electrode can be used to manufacture a nonaqueous electrolyte secondary battery or an alkaline hydrogen battery. Furthermore, these batteries can be suitably used for electronic devices (mobile phones, smart phones, tablets, power tools, home robots, drones, etc.) or automobiles (for engine starters, for regeneration of hybrid vehicles, for plugging in It is used for driving of hybrid electric vehicle, driving of electric vehicle, regeneration of fuel cell vehicle, etc.) and power storage (emergency, load leveling, etc.).

<2. Dispersion mixing device> Next, the dispersion mixing apparatus which manufactures the slurry for negative electrodes is demonstrated, and the manufacturing process of the slurry for negative electrodes using this apparatus is demonstrated. In addition, in the dispersion-mixing process in the manufacturing method of the slurry for negative electrodes, the conventional method, such as a shearing method, an ultrasonic method, a cavitation method, etc., which are generally used can be employ|adopted.

In addition, it is known that the battery performance greatly affects the electrode characteristics depending on the manufacturing conditions of the electrode slurry. Of course, in the negative electrode slurry of this embodiment, it is also preferable that the active material, the conductive assistant and the water-based binder are uniformly dispersed.

When water is used as the dispersion medium of the slurry, there are cases in which lumps or lumps of the active material or conductive aid are formed, and the non-uniformity of the dispersion state of the slurry becomes a problem. Therefore, among the above-mentioned dispersing and mixing methods, a method capable of uniformly dispersing the slurry for negative electrodes is preferable. Moreover, in this embodiment, the method of removing the excess carbon dioxide in a slurry by a cavity can also be used.

Next, based on FIGS. 1 to 5 , an apparatus for producing a slurry for a negative electrode of a non-aqueous electrolyte secondary battery (hereinafter, referred to as a “dispersion mixing apparatus”) that implements the method for producing a slurry for a negative electrode of a non-aqueous electrolyte secondary battery is described. )Be explained. In addition, although the following embodiment uses the slurry for negative electrodes of a non-aqueous electrolyte secondary battery as an example, this invention is not limited to this.

[Overall structure] The mixing apparatus of this embodiment is shown in FIG. 1 . The dispersing and mixing apparatus uses the solid content P as a dispersoid and the solvent R as a dispersion medium to disperse and mix the solid content P in the solvent R to generate a slurry S.

In the present embodiment, for example, as the solid content P, the negative electrode active material, the conductive auxiliary agent, and the water-based binder, which are alloy-based materials for producing a slurry material for electrodes for non-aqueous electrolyte secondary batteries, are used, and water is used. as solvent R.

As shown in FIG. 1 , the dispersion mixing apparatus includes a suction stirring pump X (suction stirring part) and a solvent storage tank Y as main components.

[Solvent storage tank] In this embodiment, the solvent storage tank Y not only has the function of circulating the solvent R through the circulation channels 16 and 18 between the solvent storage tank Y and the suction stirring pump X, but also has the solvent R (solid content as needed). P) supply function. In addition, before the suction and stirring pump X starts to operate, a predetermined amount of solvent R (solid content P, if necessary) for generating the above-mentioned raw material slurry is put into and stored in the solvent storage tank Y, or is While the suction and stirring pump X circulates the solvent R, the solid content P is fed into the solvent storage tank Y.

Here, as a method of supplying the solid content P, in this embodiment, as shown in FIG. 5 , a solid content storage hopper 31 for storing a predetermined amount of the solid content P is provided, and then, the solid content stored in the solid content P is The solid component P in the material component storage hopper 31 is sequentially supplied from the first supply unit 11 to the supply unit 11 by direct negative pressure suction through the input shutter 31a by the action of the negative pressure generated by the rotation of the stirring blade 6. The inside of the casing 1 of the stirring pump X is sucked.

Furthermore, as a method of supplying the solid content P, in addition to the above, similarly, the solvent R may be supplied from the solvent storage tank Y to the suction stirring pump X with respect to the solid content stored in the solid content storage hopper. In the middle of the circulation flow path 16, it is sucked by the ejector effect obtained by the flow of the solvent R, and is supplied to the suction stirring pump X together with the solvent R. Also, as shown in FIG. 6( a ), the solvent R and the solid content P may be put into and stored in the solvent storage tank Y in advance, or a predetermined amount of the solvent R and the solid content may be mixed using a stirring and mixing device or the like. The raw material slurry produced by stirring and mixing the component P is put in and stored in the solvent storage tank Y.

Furthermore, when supplying the solvent R or the raw material slurry to the suction stirring pump X, in addition to the suction force of the suction stirring pump X, a liquid feeding pump (not shown) may be used. In addition, the configuration of the solvent storage tank Y is not particularly limited as long as it has a storage function, and for example, a stirring mechanism (not shown) may be used.

Specifically, as shown in FIG. 6( b ), a stirring and mixing device such as a planetary mixer may be used instead of the solvent storage tank Y, and a predetermined amount of the solvent R and the solid content P may be stirred and mixed, The raw material slurry is produced, and the produced raw material slurry is supplied to the suction stirring pump X.

[Suction stirring pump] Based on FIG. 5 , the suction stirring pump X will be described. The suction and stirring pump X includes a casing 1 including a cylindrical outer peripheral wall 4 whose both ends are closed by a front wall 2 and a rear wall 3 . Also includes: a rotor 5 that is concentrically rotatably disposed inside the casing 1; a cylindrical stator 7 that is fixedly arranged on the front wall portion 2 concentrically inside the casing 1; and The pump drives a motor M or the like, which rotationally drives the rotor 5 .

Further, a plurality of stirring blades 6 are provided on the radially outer side of the rotor 5, and the plurality of stirring blades 6 are integrally formed with the rotor 5 in a state of protruding toward the front side as the front wall portion 2 and being arranged at equal intervals in the circumferential direction. .

The cylindrical stator 7 is provided with a plurality of through holes 7a and 7b which are arranged in the circumferential direction, respectively, and serve as throttle passages. In addition, the stator 7 is located on the front side of the rotor 5 and radially inward of the stirring blade 6, and is fixedly arranged on the front wall portion 2. Between the stator 7 and the outer peripheral wall portion 4 of the casing 1, a discharge chamber is formed. An annular wing chamber 8 for the stirring blade 6 to surround. Moreover, the 1st supply part 11 is provided in the position shifted to the outer peripheral side rather than the center axis|shaft of the front wall part 2 (axis center of the drive shaft 19 of the motor M).

Here, in the present embodiment, a solid content storage hopper 31 is provided, and the solid content P stored in the solid content storage hopper 31 is directly sucked from the first negative pressure through the input shutter 31a. The supply part 11 supplies the inside of the casing 1 of the suction stirring pump X.

Similarly, by introducing carbon dioxide from the first supply part 11 into the first introduction chamber 13 of the casing 1, the carbon dioxide is directly sucked into the casing 1 of the suction and stirring pump X under negative pressure, and the raw material flowing along the path The slurry S supplies carbon dioxide. Thereby, carbon dioxide can be dissolved in the raw material slurry S, and the generation of hydrogen can be suppressed.

The cylindrical ejection portion 12 for ejecting the raw material slurry S produced by mixing the solvent R and the solid content P is provided in the casing in a state of extending in the tangential direction of the outer peripheral wall portion 4 and communicating with the wing chamber 8 . A portion in the circumferential direction of the cylindrical outer peripheral wall portion 4 of 1 . Thereby, the raw material slurry S discharged from the discharge part 12 is returned to the solvent storage tank Y through the circulation flow path 18 .

Moreover, the 2nd supply part 17 is provided in the center part (axis center of the drive shaft 19 of the motor M) of the front wall part 2 of the casing 1. As shown in FIG. In addition, the second supply part 17 is supplied with the solvent R (raw material slurry S returned to the solvent storage tank Y) which is put into and stored in the solvent storage tank Y by negative pressure suction through the circulation flow path 16 . .

In addition, a partition plate 15 that divides the inner peripheral side of the stator 7 into the first introduction chamber 13 on the front wall portion 2 side and the second introduction chamber 14 on the rotor 5 side is provided on the rotor in a state of integral rotation with the rotor 5 . The front side of the partition plate 15 and the front wall portion 2 side of the partition plate 15 are provided with scraping wings 9. A plurality of scraping vanes 9 are arranged concentrically at equal intervals in the circumferential direction, and each scraping vane 9 is arranged so as to be able to surround the rotor 5 integrally with the front end thereof entering the annular groove 10 .

The first introduction chamber 13 and the second introduction chamber 14 are configured to communicate with the wing chamber 8 through the plurality of through holes 7 a and 7 b of the stator 7 , and the first supply portion 11 and the first introduction chamber 13 are configured to communicate with the second supply portion. 17 communicates with the second introduction chamber 14 .

Specifically, the first introduction chamber 13 and the wing chamber 8 communicate with each other through a plurality of through holes 7 a on the side of the first introduction chamber 13 , and the through holes 7 a are arranged in the stator 7 at equal intervals in the circumferential direction and face the first introduction chamber 13 . 1. Part of the introduction chamber 13. In addition, the second introduction chamber 14 and the wing chamber 8 are communicated through a plurality of through holes 7b on the side of the second introduction chamber 14, and the through holes 7b are arranged in the stator 7 at equal intervals in the circumferential direction and face the second introduction. Part of room 14.

Next, each part of the suction stirring pump X is demonstrated. The rotor 5 has a shape in which the front surface is bulged in a substantially frustoconical shape, and a plurality of stirring blades 6 are arranged at equal intervals on the outer peripheral side of the rotor 5 in a state of protruding forward. A plurality of stirring blades 6 are arranged at equal intervals in the circumferential direction. The stirring blade 6 is formed to protrude from the outer peripheral side to the inner peripheral side of the rotor 5 so as to incline backward in the rotation direction as it goes from the inner peripheral side to the outer peripheral side, and the inner diameter of the front end of the stirring blade 6 is formed to be slightly larger than the outer diameter of the stator 7 .

The rotor 5 is disposed in the casing 1 concentrically with the casing 1, and in this state is connected to the drive shaft 19 of the pump drive motor M which penetrates the rear wall 3 and is inserted into the casing 1, and is driven by the pump The motor M rotationally drives it.

In addition, a mechanical shaft seal 22 is provided on the drive shaft 19 of the pump drive motor M, which constitutes a seal portion for preventing the solvent R inside the casing 1 from leaking to the pump drive motor M side.

In addition, the rotor 5 is configured such that a so-called cavity (partial boiling) is generated on the surface (back surface) which becomes the rear side of the rotation direction of the stirring blade 6 by driving the rotor 5 to rotate in a direction in which the front end of the stirring blade 6 becomes the front side.

The partition plate 15 is formed in a substantially funnel shape whose outer diameter is slightly smaller than the inner diameter of the stator 7 . The spacer plate 15 is attached to the front surface of the rotor 5 via the spacer holding member 20 , and is configured to rotate integrally with the rotor 5 when the rotor 5 is rotationally driven.

In the present embodiment, the cylindrical second supply portion 17 is provided at the center portion of the front wall portion 2 of the case 1 concentrically with the case 1 .

The first supply portion 11 is provided on the front wall portion 2 so as to be located on the lateral side of the opening portion of the second supply portion 17 that faces the inside of the casing 1 . Moreover, the 1st supply part 11 is provided in the front wall part 2 of the casing 1 in an inclined state. In addition, the inclination angle of the first supply part 11 is about 45 degrees.

Moreover, in this embodiment, the solid content P stored in the solid content storage hopper 31 can be sequentially supplied to the first supply part 11 via the input shutter 31a, and carbon dioxide can be introduced.

The stator 7 is mounted on the inner surface of the front wall portion 2 of the housing 1 (the surface facing the rotor 5 ), and the front wall portion 2 of the housing 1 and the stator 7 are fixed integrally. When the stirring blade 6 of the rotor 5 rotates, the raw material slurry S is ejected through the ejection part 12, and the solvent R inputted and stored in the solvent storage tank Y, or the raw material returned to the solvent storage tank Y is introduced through the second supply part 17. The slurry S is therefore decompressed in the suction stirring pump X.

The partition plate 15 provided with the scraping blade 9 is installed on the front surface of the rotor 5 through the spacer holding member 20 in a state of being spaced apart from the front surface of the rotor 5. The rotor 5 is connected with the front end of the partition plate 15 and the second The supply portion 17 is disposed in the casing 1 in a state of being spaced apart and facing each other. Thereby, the structure is such that between the bulging front surface of the rotor 5 and the rear surface of the partition plate 15, a second introduction chamber 14 having a thin front end whose diameter decreases as it approaches the front wall portion 2 side of the casing 1 is formed. The supply portion 17 communicates with the second introduction chamber 14 via the front end portion of the partition plate 15.

Furthermore, an annular first introduction chamber 13 communicating with the first supply portion 11 is formed between the front wall portion 2 of the casing 1 and the front surface of the partition plate 15 . Furthermore, when the rotor 5 is driven to rotate, the partition plate 15 and the rotor 5 are rotated integrally, and the second supply portion 17 is maintained via the front end portion of the partition plate 15 even when the rotor 5 and the partition plate 15 are rotated. A state in which it communicates with the second introduction chamber 14 .

[Control Department] Although not shown in the figure, the control unit included in the dispersing and mixing device is constituted by a known arithmetic processing device including a CPU, a memory unit, and the like, and is configured to be able to control the operation of the suction and stirring pump X constituting the dispersing and mixing device. .

In particular, the control unit is configured to be able to control the peripheral speed of the stirring blade 6 (the number of revolutions of the rotor 5), and to set the pressure of the stirring blade 6 so that the pressure in the first introduction chamber 13 and the second introduction chamber 14 becomes a predetermined negative pressure state. Peripheral speed (number of revolutions of rotor 5). In this way, by rotating the stirring blade 6 at the set peripheral speed (the number of revolutions of the rotor 5 ), at least the through hole 7 b (and the first introduction chamber 14 ) of the stator 7 immediately after passing through the second introduction chamber 14 can be made to pass through. The region in the wing chamber 8 behind the through hole 7a) on the 13 side is continuously formed as a micro bubble region where a large amount of micro bubbles of the solvent R are generated over the entire circumference of the wing chamber 8 .

[Operation of the dispersing and mixing device (slurry production step)] Next, the operation of the dispersing and mixing device (the production step of the slurry) will be described. First, before the operation of the suction and stirring pump X is started, a predetermined amount of the solvent R is put in and stored in the solvent storage tank Y.

When the suction and stirring pump X starts to operate (high-speed operation) in this state, the suction and stirring pump X is in a negative pressure state, and the solvent R injected and stored in the solvent storage tank Y passes through the circulation flow path 16 by the negative pressure. It is supplied to the 2nd supply part 17 by pressure suction (step 1).

In this state, a predetermined amount of solid content P is sequentially supplied from the solid content storage hopper 31 to the suction and stirring pump X from the first supply portion 11 through the input shutter 31a by direct negative pressure suction. into the first introduction chamber 13 of the casing 1 (step 2).

In addition, in this embodiment, although the example in which the solid content P was injected|thrown-in from the solid content storage hopper 31 was shown, you may inject|throws-in the solid content P into the solvent storage tank Y in advance.

The solid content P supplied from the first supply part 11 to the first introduction chamber 13 of the casing 1 of the suction and stirring pump X is introduced into the wing chamber 8 together with the solvent R supplied to the second supply part 17 , The raw material slurry S is discharged from the discharge unit 12 and returned to the solvent storage tank Y via the circulation flow path 18 . Then, while the suction stirring pump X is operating, the raw material slurry S is circulated by negative pressure suction through the circulation flow path 16 (step 3 ).

Then, the raw material slurry S circulated to the second supply part 17 is introduced into the second introduction chamber 14, and is crushed by shearing when passing through the through hole 7b on the second introduction chamber 14 side. At this time, the flow rate is introduced into the wing chamber 8 through the through hole 7b on the side of the second introduction chamber 14 in a state where the flow rate is restricted. Then, in the wing chamber 8, it is subjected to expansion and contraction of fine air bubbles generated by cavities (partial boiling) generated on the back surface of the stirring blade 6 rotating at a high speed, and shearing action by the stirring blade 6. The raw material slurry S in which the aggregate (agglomeration) of the solid content P is reduced by being crushed is ejected from the ejection part 12 .

Here, the control unit is configured to be able to control the peripheral speed of the stirring blade 6 (the number of revolutions of the rotor 5 ), and to set the peripheral speed of the stirring blade 6 (the rotor 5 ) so that the pressure in the second introduction chamber 14 becomes a predetermined negative pressure state. of revolutions). By rotating the stirring blade 6 at the set peripheral speed (the number of revolutions of the rotor 5), the blade chambers immediately after passing through the through holes 7a and 7b on the side of the first introduction chamber 13 and the second introduction chamber 14 of the stator 7 can be made to rotate. The region within 8 is formed as a micro-bubble region in which a large amount of micro-bubbles of the solvent R are continuously generated around the entire circumference of the wing chamber 8 .

In this way, the solvent R permeating the agglomerates (so-called agglomerates) of the solid content P is foamed over the entire circumference of the wing chambers 8 to promote the crushing of the agglomerates, and further, the generated fine air bubbles are formed in the wing chambers. 8 is repeatedly expanded and contracted by decompression and pressurization, further promoting the dispersion of the solid content P. As a result, it is possible to generate a high-quality raw material slurry S in which the solid content P is well dispersed in the solvent R in almost the entire raw material slurry S existing in the entire circumference of the wing chamber 8 .

[Introduction of carbon dioxide] Next, the operation (introduction of carbon dioxide) of the dispersing and mixing apparatus will be described. While continuously operating the suction and stirring pump X, carbon dioxide was introduced into the raw material slurry S to suppress the generation of hydrogen.

In this process, carbon dioxide is introduced into the first introduction chamber 13 of the casing 1 by the carbon dioxide supply mechanism G, and carbon dioxide is supplied to the raw material slurry S flowing along the path, whereby the carbon dioxide is dissolved in the raw material slurry S and self-slurrying is suppressed. produce hydrogen.

Here, in addition to the first introduction chamber 13 of the casing 1 of the present embodiment, the carbon dioxide introduction site is set to any of the second introduction chamber 14 , the annular wing chamber 8 around which the stirring blade 6 surrounds, the circulation flow path 16 , and the like. A carbon dioxide supply mechanism G can be connected.

In this case, carbon dioxide is preferably introduced along the flow direction of the flowing raw material slurry S (toward the tangential direction of the flow direction).

In addition, in this embodiment, the timing of introducing carbon dioxide is set to the above-mentioned step 3 (after the raw material slurry S is produced (subsequent supply)), and as shown in FIG. 7 , it may be set to the above-mentioned step 2 (while the solvent R flows along the path, and the solid content P and carbon dioxide (supplied simultaneously with the solid content P) are supplied to the solvent R flowing along the path. In addition, the above-mentioned step 1 (supplying carbon dioxide (inorganic carbon) to the solvent R flowing along the path while flowing the solvent R along the path (supplied in advance)) may be set, and these steps may be appropriately combined and implemented.

Here, by flowing the raw material slurry S in the cavity generation region, cavities are generated (partial boiling), and carbon dioxide is introduced. Thereby, the carbon dioxide bubbles are repeatedly expanded and contracted by cavities (partial boiling), the contact area with the solvent or the raw material slurry is increased, the generation of hydrogen can be suppressed, and a negative electrode with a thin oxide film can be formed.

[Operation of the dispersing and mixing device (degassing treatment step)] Next, the operation (degassing treatment step) of the dispersion mixing apparatus will be described. In this degassing treatment, carbon dioxide in the slurry can be removed by operating the suction and stirring pump X (high-speed operation) for a predetermined time to generate cavities (partial boiling).

Then, the raw material slurry S (slurry for the negative electrode of the non-aqueous electrolyte secondary battery) whose degassing treatment has been completed is supplied to the subsequent step through the discharge pipe 18 a provided in a state of being communicated with the wing chamber 8 . After that, the operation of the suction and stirring pump X is stopped.

Furthermore, the step including the degassing treatment step is an example of the present embodiment, and is not an essential step in the present invention. That is, in the case where a predetermined amount of carbon dioxide set in advance is introduced into the raw material slurry S, the degassing treatment step may be omitted.

In addition, although the example in which carbon dioxide was introduced along the flow direction of the flowing raw material slurry was shown in the above-mentioned embodiment, the example of introduction of carbon dioxide is not limited to this. For example, carbon dioxide may be introduced into the slurry provided in the solvent storage tank Y by providing a carbon dioxide introduction part in the solvent storage tank Y.

However, in order to dissolve carbon dioxide in the slurry, it is necessary to pressurize, and it is necessary to dissolve carbon dioxide in the slurry in a state where the pressure is 0.1 to 0.5 MPa. In this embodiment, carbon dioxide can be supplied to the stationary raw material slurry instead of the flowing raw material slurry, so it has the advantage that it is not limited to this device, and can be realized by any stirring device.

<3. Production of Negative Electrode Active Material Granules> Next, the production of the negative electrode active material granules will be described. The negative electrode slurry of the non-aqueous electrolyte secondary battery of this embodiment can also be used as an active material by spray-drying and granulating. In this case, a known granulation method can be applied, for example, a fluidized bed granulation method, agitation granulation method, roll granulation method, spray drying method, extrusion granulation method, roll granulation method and coating method can be used. Negative electrode active material granules are produced by a cloth granulation method or the like. Among them, the spray drying method and the fluidized bed granulation method are particularly preferred.

By granulating the active material with smaller particle size together with the binder, the stress imparted to the current collector due to the expansion and contraction of the negative electrode active material can be relieved, and the deformation of the current collector can be prevented. Also, the amount of adhesive required for the electrodes can be reduced.

In the spray drying method, for example, the above-mentioned negative electrode slurry is sprayed from above in a greenhouse heated to 50-300° C. under the conditions of 1-30 mL/min and air pressure of 0.01-5 MPa to form aggregated particles, This was dried to obtain granules.

In the fluidized bed granulation method, for example, the powder raw material is placed in a fluidized bed granulation device, and warm air heated to 50 to 300°C is fed from below to make the powder raw material (granulate precursor) flow and form. After mixing, spray the above-mentioned negative electrode slurry to the mixed powder raw material with a nozzle from above, and spray the skeleton-forming agent on the surface of the powder uniformly under the conditions of 1-30 mL/min and air pressure of 0.01-5 MPa to form aggregated particles , and dried to obtain granules.

The median particle diameter (D50) of the active material granules is preferably adjusted to 0.1 μm to 50 μm, more preferably 0.5 μm to 30 μm, and still more preferably 0.55 μm to 20 μm. By making the median particle diameter (D50) within the above-mentioned range, an electrode material capable of obtaining an electrode excellent in output characteristics and cycle life characteristics can be obtained. When the median particle size (D50) is 0.1 μm or more, the specific surface area will not be too high, and the binder required to form the electrode will not increase. As a result, the output characteristics and energy density of the electrode were excellent. On the other hand, since the median particle diameter (D50) is 50 μm or less, it is easy to adjust the capacitance when designing the capacitance per unit area of the electrode.

The carbon dioxide contained in the negative electrode slurry is vaporized and dispersed in the atmosphere by drying, so that the active material granules can be produced without impairing the gravimetric energy density of the electrode.

The active material granules thus obtained can be used as the active material of the above-mentioned negative electrode slurry.

<4. Manufacturing of negative electrode> As a manufacturing method of the negative electrode of the non-aqueous electrolyte secondary battery of this embodiment, the method of apply|coating or filling the said slurry for negative electrodes in a collector, drying it temporarily, and performing heat processing to obtain a negative electrode can be mentioned.

The temporary drying is not particularly limited as long as it is a method of volatilizing and removing the solvent in the slurry, for example, a method of performing heat treatment in the atmosphere at a temperature of 50 to 400°C. The above heat treatment can be performed by maintaining the temperature at 50 to 400° C. for 0.5 to 50 hours in a non-oxygen atmosphere. Examples of the non-oxygen atmosphere include a reduced pressure atmosphere, a helium atmosphere, a neon atmosphere, an argon atmosphere, a nitrogen atmosphere, and a hydrogen atmosphere.

The current collector is not particularly limited, as long as it has electronic conductivity, is energized with the negative electrode material held, and is excellent in oxidation resistance. For example, metals such as carbon, titanium, chromium, aluminum, gold, copper, nickel, stainless steel, etc., or carbon, and alloys containing such metals or carbon (eg, stainless steel, ANVILOY steel, Hearst alloy steel, etc.) can be used. Moreover, the material which coat|covered the surface of the said metal with carbon may be sufficient.

The shape of the current collector is wire-like, rod-like, plate-like, foil-like, mesh-like, woven, non-woven, expanded, embossed, porous or foamed. An expanded body, an embossed body, or a foamed body is preferred; if the purpose is to reduce cost, a foil-like body or a porous body is preferred.

The thickness of the active material layer of the negative electrode varies depending on the capacity density of the negative electrode, but is preferably 0.5 to 500 μm, for example. By setting the thickness of the active material layer of the electrode within this range, the current collector supports the electrode active material, and a practical capacitance can be obtained. However, when the shape of the current collector is any of mesh, woven, non-woven, expanded, embossed, porous, or foam, it is preferable that the current collector has a thickness of 1 to 1000 μm. active material layer.

The negative electrode capacity density is preferably 0.1 to 20 mAh/cm ² . For example, when the negative electrode of this embodiment is obtained with a negative electrode capacity density of 0.1 to 2 mAh/cm ² , it is suitable for ultra-high output applications; when the negative electrode capacity density is 0.5 to 3 mAh/cm ² , it is suitable for long-life applications or high Output application; when the negative electrode capacity density is 3-30 mAh/cm ² , it is suitable for high-capacity applications. In addition, the negative electrode capacity density can be measured, for example, by a charge-discharge cycle capacity test or the like, or the capacity can be calculated from the active material coating mass, and the value can be divided by the electrode area.

<5. Manufacture of batteries> The negative electrode thus obtained is joined to the electrolyte via the positive electrode, and is sealed in a state of being immersed in the electrolytic solution to form a secondary battery.

As for the electrolyte, in the case of a non-aqueous electrolyte secondary battery, it may be a liquid or a solid that can move the carriers from the positive electrode to the negative electrode or from the negative electrode to the positive electrode, and can be used in a known non-aqueous electrolyte secondary battery. The electrolytes are the same. For example, electrolyte solution, gel electrolyte, solid electrolyte, ionic liquid, molten salt are mentioned. Here, the electrolytic solution refers to an electrolytic solution in a state in which the electrolyte is dissolved in a solvent.

The electrolyte needs to contain ions as carriers. For non-aqueous electrolyte secondary batteries, suitable electrolytes include, for example, alkali metal salts such as lithium salts, sodium salts, and potassium salts; alkaline earth metal salts such as magnesium salts and calcium salts; and aluminum salts. More specifically, at least one or more selected from the group consisting of the following compounds can be used: lithium hexafluorophosphate (LiPF ₆ ), lithium perchlorate (LiClO ₄ ), lithium tetrafluoroborate (LiBF ₄ ), trifluoromethanesulfonate Lithium oxide (LiCF ₃ SO ₄ ), lithium bis-trifluoromethanesulfonimide (LiN(SO ₂ CF ₃ ) ₂ ), lithium bis-pentafluoroethane sulfonimide (LiN(SO ₂ C ₂ F ₅ ) ₂ ) , Lithium Bisoxalate Borate (LiBC ₄ O ₈ ), Sodium Hexafluorophosphate, Sodium Perchlorate, Sodium Tetrafluoroborate, Sodium Trifluoromethanesulfonate and Sodium Trifluoromethanesulfonimide, Potassium Hexafluorophosphate, Potassium Perchlorate , potassium tetrafluoroborate, potassium trifluoromethanesulfonate, potassium trifluoromethanesulfonimide, magnesium perchlorate, calcium perchlorate, aluminum chloride, etc.

烷（DIOX）、冠醚、二甲氧基甲烷（DMM）、二甲氧基乙烷（DME）、二乙二醇二甲醚（diglyme）、三乙二醇二甲醚（triglyme）、四乙二醇二甲醚（tetraglyme）、乙酸甲酯（MA）、乙酸乙酯（EA）、乙酸丙酯、乙酸異丙酯、乙酸丁酯、氟乙酸甲酯、三氟乙酸乙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、甲酸甲酯、甲酸乙酯、甲酸丙酯、丁酸乙酯、丁酸丙酯、甲基丁酸丙酯、乙酸乙烯酯、氰基乙酸甲酯、γ-戊內酯、σ-戊內酯、ε-己內酯、γ-己內酯、γ-十一碳內酯、磷酸三甲酯（TMP）、磷酸三乙酯（TEP）、磷酸三正丙酯、磷酸三辛酯、磷酸三苯酯、N,N-二甲基甲醯胺（DMF）、乙二胺、吡啶、N-甲基咪唑、硫酸二甲酯、亞硫酸二甲酯、亞硫酸二丙酯、亞硫酸乙烯酯（ethylene sulfite）、二甲基碸、乙基甲基碸、二苯基碸、環丁碸、甲基環丁碸、甲磺酸甲酯、苯磺酸甲酯、三氟甲磺酸甲酯、丙磺酸、丁磺酸、二甲基亞碸、二苯二硫醚、二甲硫醚、二乙硫醚、乙腈、丙腈、己二腈、戊腈、戊二腈、丙二腈、丁二腈、庚二腈、辛二腈、異丁腈、聯苯、琥珀酸酐、第三丁基苯、萘、環己基苯、苯并三唑、噻吩、甲苯、甲基乙基酮、苯、氟苯、六氟苯、硝基甲烷、N,N-二甲基甲醯胺、二甲基亞碸、碳酸伸乙烯酯（VC）、碳酸乙烯基伸乙酯（EVC）、碳酸氟乙烯酯（FEC）、亞硫酸乙烯酯（ES），尤佳為PC單一成分、EC與DEC之混合物、或γ-丁內酯單一成分。再者，上述EC與DEC之混合物之混合比可在EC及DEC均為10～90 vol%之範圍內任意調整。或者，可不使用溶劑而為固體電解質，亦可於電解液中含有固體電解質。As the solvent of the electrolyte, for example, at least one selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate ( DEC), ethyl methyl carbonate (EMC), gamma-butyrolactone (GBL), methyl-gamma-butyrolactone, methyllactone, 2-methyltetrahydrofuran, 1,3-dioxo pentane (1,3-dioxolane, DOL), 4-methyl-1,3-dioxolane, 1,2-dimethoxyethane, 1,2-diethoxyethane, diethyl ether , furan, dimethylfuran, tetrahydrofuran (THF), methyltetrahydrofuran (MeTHF), tetrahydropyran (THP),

Alkane (DIOX), crown ether, dimethoxymethane (DMM), dimethoxyethane (DME), diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme), four Ethylene glycol dimethyl ether (tetraglyme), methyl acetate (MA), ethyl acetate (EA), propyl acetate, isopropyl acetate, butyl acetate, methyl fluoroacetate, ethyl trifluoroacetate, propionic acid Methyl propionate, ethyl propionate, propyl propionate, methyl formate, ethyl formate, propyl formate, ethyl butyrate, propyl butyrate, propyl methyl butyrate, vinyl acetate, methyl cyanoacetate γ-valerolactone, σ-valerolactone, ε-caprolactone, γ-caprolactone, γ-undecanolactone, trimethyl phosphate (TMP), triethyl phosphate (TEP), Tri-n-propyl phosphate, trioctyl phosphate, triphenyl phosphate, N,N-dimethylformamide (DMF), ethylenediamine, pyridine, N-methylimidazole, dimethyl sulfate, bisulfite Methyl ester, dipropyl sulfite, ethylene sulfite (ethylene sulfite), dimethyl sulfite, ethyl methyl sulfite, diphenyl sulfite, cyclobutyl sulfite, methyl cyclobutane sulfite, methyl methanesulfonate, Methyl benzene sulfonate, methyl triflate, propane sulfonic acid, butane sulfonic acid, dimethyl sulfoxide, diphenyl disulfide, dimethyl sulfide, diethyl sulfide, acetonitrile, propionitrile, hexane Dinitrile, valeronitrile, glutaronitrile, malononitrile, succinonitrile, pimeliconitrile, suberonitrile, isobutyronitrile, biphenyl, succinic anhydride, tert-butylbenzene, naphthalene, cyclohexylbenzene, benzo Triazole, thiophene, toluene, methyl ethyl ketone, benzene, fluorobenzene, hexafluorobenzene, nitromethane, N,N-dimethylformamide, dimethylsulfoxide, vinylene carbonate (VC) , vinyl ethylidene carbonate (EVC), fluoroethylene carbonate (FEC), vinyl sulfite (ES), preferably a single component of PC, a mixture of EC and DEC, or a single component of γ-butyrolactone. Furthermore, the mixing ratio of the mixture of EC and DEC can be adjusted arbitrarily within the range of 10 to 90 vol% for both EC and DEC. Alternatively, a solid electrolyte may be used without using a solvent, or a solid electrolyte may be contained in the electrolytic solution.

Examples of the solid electrolyte include sulfide-based, oxide-based, hydride-based, nitride-based, and polymer-based electrolytes. These are preferably amorphous (glass) or crystalline substances composed of alkali metal salts and inorganic derivatives. In the case of the solid electrolyte, the relative anion does not move, so the ion species responsible for conduction (for example, in the case of a lithium-ion battery, it means lithium ion; in the case of a sodium-ion battery, it means sodium ion; in the case of a potassium-ion battery, it means It means that the migration number of potassium ions) is approximately 1, thereby inhibiting side reactions and improving the utilization rate of the battery. In addition, since an organic solvent is not used like a conventional lithium ion battery using an electrolytic solution, it is expected to be a secondary battery excellent in safety that does not cause gas or liquid ignition, liquid leakage, and the like.

Ionic liquids or molten salts are classified into pyridines, alicyclic amines, aliphatic amines, and the like according to the type of cation. By selecting the type of anion to be combined with it, various ionic liquids or molten salts can be synthesized. Cations include ammonium-based, phosphonium-based ions, inorganic-based ions such as imidazolium salts, pyridinium salts, etc., and examples of anions used include bromide ions, halogen-based trifluoromethanesulfonates, and boron such as tetraphenyl borate. Phosphorus systems such as hexafluorophosphates, etc.

The ionic liquid or molten salt can be obtained, for example, by a known synthesis method, such as combining cations such as imidazolinium with Br ^- , Cl ^- , BF ₄ ^- , PF ₆ ^- , (CF ₃ SO ₂ ) ₂ N ^- , CF ₃ It consists of a combination of anions such as SO ₃ ^- and FeCl ₄ ^- . If it is an ionic liquid or a molten salt, it can function as an electrolytic solution.

On the other hand, as the electrolyte of an alkaline hydrogen battery, those used in known alkaline hydrogen batteries can be used. That is, an electrolyte solution in which LiOH, NaOH, KOH, and RbOH are dissolved in an alkaline aqueous solution, for example, in the range of 1 mol/L to 10 mol/L, can be used.

When the above-mentioned electrolyte has fluidity, it is preferable to use a separator impregnated with an electrolyte between the positive electrode and the negative electrode. As the separator, those used in known non-aqueous electrolyte secondary batteries can be used. Examples of the shape of the separator include microporous film, woven fabric, non-woven fabric, and pressurized powder. The material of the separator is not particularly limited, for example, polyethylene (PE), polypropylene (PP), PTFE, PET, polyimide (PI), polyamide, and polyamideimide are preferred. (PAI), polyaramide, polyacrylonitrile (PAN), cellulose and other materials. Moreover, the existing separator may be coated or filled with ceramics, and the heat resistance may be improved.

The structure of the battery is not particularly limited, and it can be applied to existing battery forms and structures such as a laminated battery and a wound battery.

The battery provided with the negative electrode of this embodiment has high energy density, good internal short-circuit safety, output characteristics, and high-temperature durability, and thus can be used as a power source for various electrical equipment and the like.

The battery related to this embodiment can also be a lithium ion battery, a lithium polymer battery, a lithium air battery, an all-solid lithium battery, a semi-solid lithium battery (a battery using an electrolyte and a solid electrolyte), a sodium ion battery, and a sodium polymer. Batteries, sodium-air batteries, all-solid sodium batteries, semi-solid sodium batteries, potassium-ion batteries, potassium-polymer batteries, potassium-air batteries, all-solid potassium batteries, semi-solid potassium batteries, magnesium-ion batteries, magnesium-air batteries, calcium-ion batteries , calcium air battery, aluminum ion battery, nickel hydrogen battery (Ni-MH), nickel hydrogen battery (Ni-H ₂ ), alkaline fuel cell, etc. Among them, lithium-ion batteries, lithium polymer batteries, lithium-air batteries, all-solid lithium batteries, and semi-solid lithium batteries are preferred from the viewpoint of voltage and capacity in a single cell.

The battery of this embodiment can be used as a power source for various electrical equipment (including electric vehicles) because of its excellent manufacturing cost and mass productivity. [Example]

Next, the embodiments of the present invention will be described, but the present invention is not limited to these embodiments. [Relationship between Si particle size and hydrogen generation] (Example of using acrylic adhesive) The negative electrode slurries (Experimental Examples 1 to 4) were prepared as follows: Si powder shown in Table 1 was used as an active material, carbon black (CB) and vapor-grown carbon fiber (VGCF) were used as conductive aids, and acrylic-based Binder As a binder, the ratio of Si: CB: VGCF: acrylic binder = 91:4:1:4 mass %, using a rotary revolution mixer (manufactured by Thinky, Debubbling Rentaro), at a speed of 2000 rpm, Mix with water under the conditions of a mixing time of 15 minutes and a defoaming treatment time of 1 minute. The negative electrode slurry was left to stand in an environment of 25° C. for 24 hours, and the appearance of the slurry before and after the stand was confirmed. Fig. 9 shows photographs for comparison before and after the slurries of Experimental Examples 1 to 4 were left to stand.

[Table 1] Median particle size (D50) BET specific surface area Experimental example 1 41 nm 65 m ² /g Experimental example 2 74nm 36 m ² /g Experimental example 3 2 μm 4 m ² /g Experimental example 4 9 μm Not determined

As can be seen from FIG. 9 , it was confirmed that the slurries containing the nano-sized Si powder (Experimental Example 1 and Experimental Example 2) had a good appearance immediately after mixing, but the slurries foamed over time. On the other hand, in Example 3 with a particle diameter of 2 μm, although foaming of the slurry was not confirmed, it was confirmed that the sensor reacted when the hydrogen detector was brought close to the slurry. Although the hydrogen sensor reacted in the slurries of Experimental Examples 1 to 3, it did not react in Example 4.

(Example of using SBR adhesive) For the negative electrode slurry (Experimental Examples 5 to 8), the Si powder shown in Table 1 was used as the active material, carbon black (CB) and vapor-grown carbon fiber (VGCF) were used as conductive aids, and SBR binder was used as the binder. , using carboxymethyl cellulose sodium salt (CMC-Na) as a tackifier, set as Si:CB:VGCF:SBR binder:CMC-Na=91:4:1:3:1 mass % ratio, except Other than that, it is the same as Experimental Examples 1-4. FIG. 10 shows photographs for comparison before and after the slurries of Experimental Examples 5 to 8 were left to stand.

10 , it was confirmed that the slurries containing the nano-sized Si powder (Experimental Examples 5 and 6) had a good appearance immediately after mixing, but the slurries foamed with time. On the other hand, in Example 7 with a particle diameter of 2 μm, although foaming of the slurry was not confirmed, it was confirmed that the sensor reacted when the hydrogen detector was brought close to the slurry. Although the hydrogen sensor reacted in the slurries of Experimental Examples 5-7, it did not react in Example 8.

[Relationship between pH value of slurry and hydrogen generation amount] The negative electrode slurry (solid ratio of 12.5 to 14.3 mass %) was obtained as follows: Si (particle size: 74 nm, specific surface area: 36 m ² /g) and Table 2 The aqueous solution with the specified pH value shown is weighed in a mass ratio of 1:7 and put into a small glass bottle. After sealing the injection port with a rubber stopper, use an autorotating revolution mixer (manufactured by Thinky, Debubbling Rentaro) to spin the solution. Mixing was carried out under the conditions of 2000 rpm and 10 minutes of mixing time. As shown in Figure 11, the hydrogen generation test was carried out in the following manner: the small glass bottle was immersed in a constant temperature water bath at 45°C, the injection needle was inserted into the rubber stopper, the water displacement method was used, and the liquid released from the small glass bottle was collected by a graduated cylinder. out gas. Furthermore, the collected gas was confirmed to be hydrogen by a hydrogen detector and an ignition test.

[Table 2] pH (25℃) solute or disperse concentration 1.7 KH ₃ (C ₂ O ₄ ) ₂ 0.05 mol/kg 4.0 C ₆ H ₄ (COOK)(COOH) 0.05 mol/kg 6.1 None (pure water) - 6.9 KH ₂ PO ₄ +Na ₂ HPO ₄ 0.05 mol/kg 7.4 SBR adhesive 2.0 wt.% 9.2 Na ₂ B ₄ O ₇ 0.05 mol/kg 10.0 NaHCO ₃ +Na ₂ CO ₃ 0.05 mol/kg

Fig. 12 shows the relationship between the hydrogen generation amount and the standing time at each pH. The hydrogen production per unit mass of silicon after 1 hour was 10.9 mL/g at pH 1.7, 14.2 mL/g at pH 4.0, 16.4 mL/g at pH 6.1, and 112 mL/g at pH 6.9 g, 306 mL/g at pH 9.2 and 852 mL/g at pH 10.0. It can be seen that when the pH value is 6.9 or more, the hydrogen gas generation rate is high and the hydrogen gas generation amount is also increased, and the hydrogen generation can be significantly suppressed by making the pH value 6.1 or less. In addition, the pH value of the Si suspension was not observed to change significantly before and after hydrogen generation.

In addition, the theoretical pH of pure water is 7.0, and in general, the pH is 6 to 7 after several minutes after absorbing carbon dioxide in the atmosphere. In this test, the pH of pure water was 6.1. Comparing the results of pH 6.1 and pH 7.4, it was found that hydrogen gas was difficult to generate when only the pure water and Si were mixed. However, if it contains a small amount of binder or tackifier, a large amount of hydrogen is generated. From this result, it is considered that the cause of the foaming of the negative electrode slurry in the above [Relationship between Si particle size and hydrogen generation] is that the pH value of the slurry is raised by the aqueous binder and the thickener, and hydrogen gas is generated.

[Relationship between the amount of hydrogen gas generated when carbon dioxide is dissolved and the standing time (1)] The negative electrode slurry (solid ratio: 13.5 mass %) of the comparative example was obtained as follows: Si (particle size: 74 nm, specific surface area: 36 m) ² /g) and SBR binder in a mass ratio of 93:7 and put it into a small glass bottle. After sealing the injection port with a rubber stopper, use an autorotating revolution mixer (manufactured by Thinky, Debubbling Rentaro) to turn Mixing was carried out under the conditions of 2000 rpm and 10 minutes of mixing time. The pH value of the negative electrode slurry of the comparative example was 7.1.

The negative electrode slurry (solid ratio: 13.5 mass %) of the Example was the same as that of Comparative Example 1, except that the SBR binder in which carbon dioxide was dissolved in advance was used. The carbon dioxide-dissolved SBR adhesive is produced by contacting carbon dioxide (absolute pressure 0.5 MPa) with the SBR adhesive under pressure for about 15 minutes. The pH value of the negative electrode slurry of the embodiment was 6.1.

As shown in Figure 11, the hydrogen generation test was carried out in the following manner: the small glass bottle was immersed in a constant temperature water bath at 45°C, the injection needle was inserted into the rubber stopper, the water displacement method was used, and the liquid released from the small glass bottle was collected by a graduated cylinder. out gas. Furthermore, the collected gas was confirmed to be hydrogen by a hydrogen detector and an ignition test.

Fig. 13 shows the relationship between the amount of hydrogen gas generated when carbon dioxide is dissolved or not and the standing time. The amount of gas generated per unit mass of silicon after standing for 1 hour was 33.2 mL/g in the example (with carbon dioxide dissolved, pH 6.1), and 134 mL/g in the comparative example (without carbon dioxide dissolved, pH 7.1). It was shown that by using the SBR binder in which carbon dioxide was dissolved, carbon dioxide was gasified and released from the slurry, and the possibility that carbon dioxide was contained in the obtained gas could not be denied, but the amount of generated gas was overwhelming compared to the comparative example. less, so the production of hydrogen can be significantly inhibited.

[Relationship between the amount of hydrogen gas generated when carbon dioxide is dissolved and the standing time (2)] The negative electrode slurries (solid ratio: 13.5 mass %) of Experimental Example A and Example B were obtained as follows: Si powder (particle size: 74 nm, specific surface area 36 m ² /g) and SBR binder (solid ratio 48.5%) were weighed in a mass ratio of 93:7, and the carbon dioxide-dissolved water was taken so that the solid ratio of the negative electrode slurry was 13.5 mass % It was put into a small glass bottle at the same time, and after sealing the injection port with a rubber stopper, the mixture was mixed with an autorotation revolution mixer (manufactured by Thinky, Debubble Rentaro) at a speed of 2000 rpm and a mixing time of 10 minutes.

Here, in Example A, carbon dioxide-dissolved water prepared in the following manner was used: 500 mL of ion-exchanged water was added to a cavity stirrer, and carbon dioxide at a flow rate of 0.1 L/min was sent to the dispersing part (6000 rpm). ), mix for 120 seconds. The pressure of the dispersion part during mixing is -0.09 to -0.06 MPa (G). The pH value of the carbon dioxide dissolved water used in Example A was 4.1. The pH value of the negative electrode slurry of Example A was 6.1.

In Example B, carbon dioxide-dissolved water prepared in the following manner was used: 500 mL of ion-exchanged water was added to a beaker, and carbon dioxide at a flow rate of 0.1 L/min was sent to an air diffusion device (air stone) to bubble (bubbling) 120 seconds. The pH value of the carbon dioxide dissolved water used in Example B was 4.1. The pH value of the negative electrode slurry of Example B was 6.1.

As shown in Figure 11, the hydrogen generation test was carried out in the following manner: the small glass bottle was immersed in a constant temperature water bath at 45°C, the injection needle was inserted into the rubber stopper, the water displacement method was used, and the liquid released from the small glass bottle was collected by a graduated cylinder. out gas. Furthermore, the collected gas was confirmed to be hydrogen by a hydrogen detector and an ignition test.

FIG. 13 shows the relationship between the amount of hydrogen generated and the standing time in Example A and Example B, compared with the comparative example of [Relationship between the amount of hydrogen generated when carbon dioxide is dissolved and the standing time (1)]. The amount of gas generated per unit mass of silicon after being left to stand for 1 hour was 51.0 mL/g in Example A and 62.6 mL/g in Example B. It is shown that by using water in which carbon dioxide is dissolved, carbon dioxide is gasified and released from the slurry, and the possibility that the obtained gas contains carbon dioxide cannot be denied. Therefore, the generation of hydrogen can be significantly suppressed.

In addition, compared with Example B, Example A produced less hydrogen gas. According to this result, in the method of dissolving carbon dioxide in water, the method of sending carbon dioxide to the dispersing part of the cavity mixer can suppress the generation of hydrogen, compared with the method of only sending carbon dioxide to the air diffusion device, and the It is preferable in this respect.

As mentioned above, the manufacturing method of the slurry for negative electrodes of the battery of the present invention, the slurry for negative electrodes, etc. have been described based on the embodiments, but the present invention is not limited to the contents described in the above-mentioned embodiments, and may be used in other ways. The composition may be appropriately changed within the scope of deviating from its gist. In particular, an example of an alloy-based material or a hydrogen storage alloy using a Si-based material as the negative electrode active material has been described, but the alloy-based material or the hydrogen storage alloy is not limited to this, and the present embodiment can also be applied to other alloy-based materials. material or other hydrogen storage alloys. Therefore, such other alloy-based materials or other hydrogen storage alloys are also included within the scope of the present invention.

1: Shell 2: Front wall 3: rear wall 4: Outer peripheral wall 5: Rotor 6: stirring blade 7: Stator 7a: Throttling flow path (through hole) 7b: Throttling flow path (through hole) 8: Wing chamber (exhaust chamber) 9: Scraping Wings 10: Annular groove 11: 1st Supply Section 12: Ejection part 13: 1st introduction room 14: 2nd introduction room 15: Spacer 16: Circulating flow path 17: 2nd supply department 18: Circulating flow path 19: Drive shaft 20: Spacer Keeping Member 31: Solid content storage hopper 31a: put in the brake G: Carbon dioxide supply mechanism M: Pump drive motor P: solid content R: solvent (dispersion medium) S: raw material slurry X: Suction stirring pump (suction stirring part) Y: Solvent storage tank

It is a perspective view which shows one Embodiment of the manufacturing apparatus of the slurry for negative electrodes of this invention. [Fig. 2] It is a front view of the same manufacturing apparatus. [FIG. 3] It is a top view of the same manufacturing apparatus. [FIG. 4] It is a left side view of the same manufacturing apparatus. Fig. 5 is a longitudinal sectional view showing the internal structure of the main part of the same manufacturing apparatus. [ Fig. 6 ] is a flowchart of a method for producing the slurry for negative electrodes of the present invention. [ Fig. 7 ] is a flow chart of the method for producing the slurry for negative electrodes of the present invention. Fig. 8 is a graph showing pH values of various aqueous solutions or representative aqueous binders. Fig. 9 is a photograph comparing the slurries of Experimental Examples 1 to 4 before and after being left to stand. [ Fig. 10 ] It is a photograph comparing the slurries of Experimental Examples 5 to 8 before and after being left to stand. [ Fig. 11 ] It is a conceptual diagram of a hydrogen generation test. Fig. 12 is a graph showing the relationship between the hydrogen generation amount and the standing time at each pH. Fig. 13 is a graph showing the relationship between the amount of hydrogen gas generated when carbon dioxide is dissolved or not and the standing time.

Claims (25)

A method for producing a slurry for a negative electrode comprising an active material as a solid content, an aqueous binder, and a method for producing a slurry for a negative electrode comprising a dispersion medium containing water, and The above-mentioned active material is an alloy-based material or a hydrogen storage alloy, The manufacturing method includes the following steps: The step of mixing the above-mentioned active material, the above-mentioned water-based binder and the above-mentioned dispersion medium to form a slurry; and The step of making the pH of the above slurry less than 6.9. The manufacturing method of the slurry for negative electrodes of Claim 1 whose step of making the pH of the said slurry less than 6.9 is the process of making pH 3.4 or more and less than 6.9. The method for producing a slurry for a negative electrode according to claim 1, wherein the step of making the pH of the slurry less than 6.9 is a step of dissolving an acidic solute in the dispersion medium. The method for producing a slurry for a negative electrode according to claim 3, wherein the step of dissolving an acidic solute in the dispersion medium is a step of dissolving carbon dioxide in the dispersion medium. The method for producing a slurry for a negative electrode according to claim 4, further comprising the step of generating cavitation in the slurry and removing carbon dioxide dissolved in the slurry. The method for producing a slurry for a negative electrode according to claim 4, wherein the step of dissolving carbon dioxide in the dispersion medium is a step of supplying carbon dioxide of more than 0.10 MPa and less than 10 MPa to the slurry. The method for producing a slurry for a negative electrode according to claim 4, wherein the step of dissolving carbon dioxide in the dispersion medium is a step of supplying carbon dioxide at 0.10 MPa or less to the slurry. The method for producing a slurry for a negative electrode according to claim 1, wherein the alloy-based material or the hydrogen storage alloy has a median particle size (D50) of 5 nm or more and 3 μm or less. The manufacturing method of the slurry for negative electrodes of Claim 1 whose step of making the pH of the said slurry less than 6.9 is the process of acidifying the said slurry. The method for producing a slurry for a negative electrode according to claim 1, wherein the alloy-based material or the hydrogen storage alloy-based Si-based material is used. The manufacturing method of the slurry for negative electrodes of Claim 1 whose said slurry for negative electrodes is used for the negative electrode of a non-aqueous electrolyte secondary battery. A method for producing a negative electrode, comprising the step of coating or filling a current collector with the slurry for negative electrode produced by the method for producing a slurry for negative electrode according to any one of claims 1 to 11. A manufacturing method of a battery, comprising the step of combining the negative electrode, the positive electrode and the electrolyte manufactured by the negative electrode manufacturing method of claim 12. A slurry for a negative electrode, which contains an active material as a solid component, a water-based binder, and a dispersion medium containing water, and The above-mentioned active material is an alloy-based material or a hydrogen storage alloy, The pH of the negative electrode slurry was less than 6.9. As in the slurry for negative electrode of claim 14, its pH is 3.4 or more and less than 6.9. According to the slurry for negative electrode of claim 14, acid solute is dissolved therein. According to the slurry for negative electrode of claim 16, carbon dioxide is dissolved therein. The slurry for negative electrodes according to claim 17, wherein an oxide film is formed on the surface of the particles of the alloy-based material or the hydrogen storage alloy. The slurry for negative electrodes according to claim 18, wherein the oxide film on the surface of the above-mentioned alloy-based material or the above-mentioned hydrogen storage alloy thinner than The carbon dioxide-undissolved water is used in place of the oxide film on the surface of the alloy material or the hydrogen storage alloy particle surface in the carbon dioxide-dissolved water for negative electrode slurry. The slurry for negative electrodes according to claim 14, wherein the median particle size (D50) of the alloy-based material or the hydrogen storage alloy is 5 nm or more and 3 μm or less. The slurry for negative electrodes according to claim 14, wherein the alloy-based material or the hydrogen storage alloy-based Si-based material is used. The slurry for a negative electrode according to claim 14 is used for the negative electrode of a non-aqueous electrolyte secondary battery. A negative electrode comprising a current collector and an active material layer in which the negative electrode slurry of any one of claims 14 to 22 is cured on the current collector. An apparatus for producing a slurry for a negative electrode, which disperses and mixes an alloy-based material or a hydrogen storage alloy as a solid component, an aqueous binder, and a dispersion medium containing water by a dispersing and mixing unit to produce a slurry for a negative electrode device, and The manufacturing apparatus includes a hydrogen generation suppressing unit that suppresses hydrogen gas generated by the reaction of the alloy-based material or the hydrogen storage alloy with the water. The manufacturing apparatus of the slurry for negative electrodes of Claim 24 whose said hydrogen generation suppression part has a carbon dioxide introduction part which introduces carbon dioxide into the dispersion medium or slurry containing water.

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