JP2011253678A - Manufacturing method of electrode for secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an electrode having excellent quality, which can prevent a problem such as uneven coating by using paste with restrained occurrence of an aggregate.SOLUTION: A method for manufacturing an electrode for secondary battery comprises preparing aqueous mixed material consisting of a mixture of at least active material, thickening agent and aqueous solvent; preparing binder-contained aqueous solution to adjust a pH of the binder-contained aqueous solution; and mixing the binder-contained aqueous solution after adjusting the pH into the aqueous mixed material to prepare paste to be used to form a mixture layer. Herein, the pH of the binder-contained aqueous solution is adjusted so that a difference between the pH of the aqueous mixed material and the pH of the binder-contained aqueous solution after adjusting the pH reaches within 0.3.

Description

  The present invention relates to a method for manufacturing an electrode for a secondary battery, and more particularly to a method for manufacturing an electrode including an electrode mixture layer formed from a paste-like composition using an aqueous solvent.

  Lithium ion secondary batteries, nickel metal hydride batteries, and other secondary batteries are becoming increasingly important as on-vehicle power supplies or personal computers and portable terminals. In particular, lithium ion secondary batteries that are lightweight and have a high energy density are expected to increase in demand in the future as being preferably used as high-output power sources mounted on vehicles.

In one typical configuration of this type of lithium ion secondary battery, a material (electrode active material) capable of reversibly occluding and releasing lithium ions is held in a conductive member (electrode current collector). With electrodes. For example, as a typical example of the electrode active material (negative electrode active material) used for the negative electrode, carbon-based materials such as graphite carbon and amorphous carbon are exemplified.
In producing a negative electrode having such a configuration, for example, a negative electrode active material is mixed with a binder (binder) or the like in an appropriate solvent to form a paste-like composition for forming a negative electrode mixture layer (a slurry is used as a paste-like composition). (Hereinafter referred to as “paste”), and the composition is applied to a negative electrode current collector to form a negative electrode mixture layer. Patent Documents 1 to 3 are cited as technical documents relating to the manufacture of this type of electrode.

JP 2009-066464 A JP-A-2005-310800 Republished WO 1996/13873

By the way, agglomerates may be generated when preparing a paste. When a paste containing such agglomerates is applied to an electrode current collector using a paste coating machine (for example, a die coater), there is a risk that clogging may occur in the paste coating machine, resulting in poor coating. Further, when such a paste is applied to the electrode current collector, there is a possibility that coating unevenness (paste thickness variation) may occur. In a lithium ion secondary battery including an electrode having coating unevenness, reaction unevenness occurs during charging and discharging, and there is a possibility that a defect due to lithium deposition may occur.
Therefore, it is preferable to apply the paste to the electrode current collector after filtering the previously prepared paste-like material to remove the aggregates. However, if a pasty material containing a large amount of agglomerates is filtered, the filter is likely to be clogged, and the working efficiency may be deteriorated. From the above, it is preferable that aggregates hardly occur in the paste-like material before filtering (the aggregates are small). Note that none of the techniques described in each of the above patent documents is a technique aimed at suppressing the occurrence of paste agglomerates.
Therefore, the present invention aims to create a paste preparation method in which agglomerates are not easily generated by devising a paste preparation method in advance, and using the paste prepared by such a method efficiently and with excellent quality. Another object of the present invention is to provide a method for producing an electrode for a secondary battery. Another object is to provide a secondary battery including an electrode obtained by such a manufacturing method and a vehicle including the secondary battery.

  In order to achieve the above object, according to the present invention, an electrode for a secondary battery having a structure in which a composite material layer including an active material, a thickener and a binder is held by a current collector (for example, a lithium ion secondary battery) A method for producing a non-aqueous electrolyte secondary battery electrode, typically a negative electrode, is provided. That is, in one embodiment of the production method disclosed herein, an aqueous mixed material (that is, a composition using an aqueous solvent) prepared by mixing at least the active material, the thickener, and an aqueous solvent is prepared. Preparing an aqueous solution containing the binder (a dispersion is included in the aqueous solution; the same applies hereinafter), adjusting the pH of the aqueous solution containing the binder, and adding the binder after the pH adjustment to the aqueous mixed material. And preparing a paste for forming a mixture layer (that is, a paste-like composition using an aqueous solvent) by mixing the aqueous solutions. Here, the pH of the binder-containing aqueous solution is adjusted so that the difference between the pH of the aqueous mixed material and the pH of the binder-containing aqueous solution after the pH adjustment is within 0.3.

  In the method for producing an electrode for a secondary battery provided by the present invention, a binder (aqueous solution) is mixed with an aqueous mixed material formed by mixing at least an active material, a thickener, and an aqueous solvent. A paste is being prepared. At this time, the pH of the aqueous solution containing the binder is adjusted so that the difference between the pH of the aqueous mixed material and the pH of the binder-containing aqueous solution after pH adjustment is within 0.3. For this reason, in the paste for forming a composite material layer obtained by mixing the aqueous mixed material and the binder-containing aqueous solution after pH adjustment, generation of aggregates is suppressed, and filtering can be performed efficiently. Alternatively, the paste can be supplied to the coating machine without filtering the paste, and the secondary battery electrode can be manufactured more efficiently. Therefore, according to this invention, when forming a composite material layer using the paste for composite material layer formation, the method which can prevent the coating nonuniformity of a paste and can manufacture the electrode which is excellent in quality can be provided.

  In a preferred aspect of the production method disclosed herein, the aqueous mixed material is prepared by adding a predetermined amount of the active material to a thickener solution obtained by mixing the thickener and the aqueous solvent in advance. It is prepared. A carbon material (for example, graphite) is an example of an active material that is particularly preferably used. In this way, by previously dissolving (or dispersing) the thickener in the aqueous solvent, when an active material is added to prepare an aqueous mixed material, agglomerates are generated due to the undissolved thickener. It can be prevented in advance.

  In a preferred embodiment of the production method disclosed herein, the pH of the aqueous mixed material is 7-8. When an aqueous mixed material in the above pH range is used, it is possible to produce an electrode that can suppress the generation of aggregates and has excellent quality.

In a preferred embodiment of the production method disclosed herein, the binder-containing aqueous solution is used so that the amount of permeation of the paste is at least 1.2 g / s when the mixture layer forming paste is passed through a predetermined filter. Adjust the pH.
Since the paste having such a permeation amount is in a state in which large aggregates are unlikely to exist, it is possible to manufacture an electrode in which the occurrence of coating unevenness or the like is suppressed.

Another embodiment of the method for producing an electrode for a secondary battery disclosed herein to achieve the above object is an aqueous mixing formed by mixing at least the active material, the thickener, and an aqueous solvent. Prepare a material, adjust the pH of the aqueous mixed material, prepare an aqueous solution containing the binder, mix the aqueous solution containing the binder with the aqueous mixed material after the pH adjustment, and paste for forming a mixture layer Preparing. Here, the pH of the aqueous mixed material is adjusted so that the difference between the pH of the aqueous mixed material after pH adjustment and the pH of the binder-containing aqueous solution is within 0.5.
According to such a manufacturing method, in the paste for forming a composite material layer obtained by mixing the aqueous mixed material and the binder-containing aqueous solution after pH adjustment, the generation of aggregates is suppressed, and filtering can be performed efficiently. Alternatively, the paste can be supplied to the coating machine without filtering the paste, and the secondary battery electrode can be manufactured more efficiently.

  In a preferred aspect of the production method disclosed herein, the aqueous mixed material is prepared by adding a predetermined amount of the active material to a thickener solution obtained by mixing the thickener and the aqueous solvent in advance. It is prepared. A carbon material (for example, graphite) is an example of an active material that is particularly preferably used. By preliminarily dissolving (or dispersing) the thickener in an aqueous solvent, it is possible to prevent the generation of aggregates due to the undissolved thickener when an active material is added to prepare an aqueous mixed material. Can do.

  In a preferred embodiment of the production method disclosed herein, the binder-containing aqueous solution has a pH of 7-8. When the binder-containing aqueous solution in the above pH range is used, it is possible to suppress the generation of aggregates and to manufacture an electrode having excellent quality.

In a preferred aspect of the production method disclosed herein, the aqueous mixed material is formed so that the amount of permeation of the paste is at least 1.2 g / s when the mixture layer forming paste is passed through a predetermined filter. Adjust the pH.
Since the paste having such a permeation amount is in a state in which large aggregates are unlikely to exist, it is possible to manufacture an electrode in which the occurrence of coating unevenness or the like is suppressed.

  Moreover, according to this invention, the secondary battery (for example, lithium ion secondary battery) constructed | assembled using the electrode for secondary batteries manufactured by one of the methods disclosed here is provided. Since the secondary battery is constructed using the secondary battery electrode as at least one electrode (preferably a negative electrode), it can exhibit better battery performance.

  Such a secondary battery is suitable as a battery mounted on a vehicle such as an automobile. Therefore, according to the present invention, a vehicle including any of the secondary batteries disclosed herein is provided. In particular, since the light weight and high output can be obtained, the secondary battery is a lithium ion secondary battery, and the lithium ion secondary battery is used as a power source (typically, a power source of a hybrid vehicle or an electric vehicle). A vehicle (for example, an automobile) provided as is suitable.

It is a flowchart for demonstrating the manufacturing method of the electrode for secondary batteries which concerns on one Embodiment. It is a flowchart for demonstrating the manufacturing method of the electrode for secondary batteries which concerns on other one Embodiment. It is a graph which shows the change of the paste permeation | transmission amount in the permeation | transmission amount measurement test of the negative electrode compound-material layer formation paste which concerns on the samples 1-5. It is a graph which shows the change of the paste permeation | transmission amount in the permeation | transmission amount measurement test of the negative electrode compound-material layer formation paste which concerns on samples 6-10. It is a graph which shows the change of the paste permeation | transmission amount in the permeation | transmission amount measurement test of the negative electrode compound-material layer formation paste which concerns on the samples 11-15. It is a graph which shows the change of the paste permeation | transmission amount in the permeation | transmission amount measurement test of the negative electrode compound-material layer formation paste which concerns on the samples 16-20. It is a perspective view which shows typically the external shape of the lithium ion secondary battery which concerns on one Embodiment. It is the VIII-VIII sectional view taken on the line in FIG. It is a side view which shows typically the vehicle (automobile) provided with the secondary battery which concerns on one Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described. It should be noted that matters other than matters specifically mentioned in the present specification and necessary for carrying out the present invention can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

  The method for manufacturing an electrode for a secondary battery provided by the present invention is characterized by adjusting a pH of an aqueous mixed material and a pH of an aqueous binder solution and then mixing them to prepare a mixture layer forming paste. Attached. Hereinafter, a negative electrode for a lithium ion secondary battery in which an electrode active material is formed on the surface of an electrode current collector is manufactured as a preferred example of a method for manufacturing an electrode for a secondary battery disclosed herein. However, it is not intended to limit the application target of the present invention to such an electrode or a battery.

  Hereinafter, each component of the negative electrode of the lithium ion secondary battery disclosed here will be described. The negative electrode for a lithium ion secondary battery disclosed here can have the same configuration as the conventional one. As the negative electrode current collector constituting such a negative electrode, a conductive member made of a metal having good conductivity is preferably used as in the current collector used in the negative electrode of a conventional lithium ion secondary battery. For example, a copper material, a nickel material, or an alloy material mainly composed of them can be used. The shape of the negative electrode current collector can vary depending on the shape of the lithium ion secondary battery, and is not particularly limited, and may be various forms such as a rod shape, a plate shape, a sheet shape, a foil shape, and a mesh shape. Typically, a sheet-like copper negative electrode current collector is used.

Next, the material constituting the negative electrode mixture layer formed on the surface of the negative electrode current collector will be described.
As the negative electrode active material constituting the negative electrode mixture layer formed on the negative electrode of the lithium ion secondary battery disclosed herein, as long as it is a negative electrode active material having a property capable of realizing the object of the present invention, its composition and The shape is not particularly limited. For example, carbon materials such as graphite (graphite), oxide materials such as lithium titanium oxide (Li ₄ Ti ₅ O ₁₂ ), metals such as tin, aluminum (Al), zinc (Zn), silicon (Si), or Examples thereof include metal materials composed of metal alloys mainly composed of these metal elements. A typical example is a powdery carbon material made of graphite or the like. For example, graphite particles can be preferably used.

As the carbon material, for example, those having an average particle diameter (typically an average particle diameter obtained based on an electron microscope observation or a light scattering method) of 8 to 15 μm can be preferably used. Further, it is the specific surface area measured by the BET method by nitrogen gas adsorption (in accordance with JIS Z 8830) is preferably used those about ^{3m 2} / ^g~5m 2 / g. Furthermore, those having a tap density of about 0.7 to 1.1 g / cc can be preferably used. Among these, a carbon material having a tap density of about 0.75 g / cc to 0.9 g / cc is preferable. Here, the tap density refers to a tap density when the number of taps is 250 in a powder tester USP tap density measuring apparatus (PT-S type; manufactured by Hosokawa Micron Corporation).

Moreover, as a binder (binder) contained in the negative electrode composite material layer formed on the negative electrode of the lithium ion secondary battery disclosed herein, at least an active material and a thickener are used in an aqueous solvent as described later. An aqueous paste (typically a composition prepared in the form of a paste or a slurry, hereinafter referred to as a negative electrode mixture layer formation) is added to an aqueous mixed material to be mixed to form the negative electrode mixture layer. For this reason, a polymer material that dissolves or disperses in water can be preferably employed. Examples of polymer materials that can be dispersed in water (water-dispersible) include fluorine-based resins such as polyethylene oxide (PEO), polytetrafluoroethylene (PTFE), and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA); Examples thereof include vinyl acetate copolymers; rubbers such as styrene butadiene rubber (SBR). In particular, SBR can be suitably used. As the other binder, for example, a cellulose polymer that is a water-soluble polymer material can be used.
Although the amount of the binder contained in the negative electrode mixture layer is appropriately determined, it is preferable to use about 0.3 parts by mass to 3.0 parts by mass with respect to 100 parts by mass of the negative electrode active material. More preferably, it is 0.5 mass part-2.0 mass parts.

In addition, as the thickening material contained in the negative electrode mixture layer formed in the negative electrode of the lithium ion secondary battery disclosed herein, a polymer material that is dissolved or dispersed in water can be preferably used. Cellulose polymers such as carboxymethylcellulose (CMC), methylcellulose (MC), cellulose acetate phthalate (CAP), hydroxypropylmethylcellulose (HPMC), etc .; polyvinyl alcohol (PVA) And the like are exemplified. Cellulose derivatives such as CMC are preferably used from the viewpoint of workability and stability during kneading (preparation) of the aqueous mixed material and the negative electrode mixture layer forming paste. In particular, CMC can be suitably used. As other thickeners, SBR or the like preferably used as the binder can be used.
Although the amount of the thickener contained in the negative electrode mixture layer is appropriately determined, the use of about 0.3 parts by mass to 3.0 parts by mass with respect to 100 parts by mass of the negative electrode active material is preferable. More preferably, it is 0.5 mass part-2.0 mass parts.

  Here, the “aqueous paste” is a concept indicating a composition using water or a mixed solvent mainly composed of water (aqueous solvent) as a dispersion medium of the active material. As the solvent other than water constituting the mixed solvent, one or more organic solvents (lower alcohol, lower ketone, etc.) that can be uniformly mixed with water can be appropriately selected and used.

Next, the preferable aspect of the manufacturing method of the negative electrode (typically negative electrode sheet | seat) for lithium ion secondary batteries which concerns on 1st Embodiment is demonstrated, referring FIG.
As shown in FIG. 1, the manufacturing method according to the present embodiment includes a negative electrode in which a negative electrode mixture layer including a negative electrode active material, a thickener, and a binder is formed (held) on the surface of a negative electrode current collector. A method for producing an ion secondary battery, wherein (1) a step of preparing an aqueous mixed material obtained by mixing at least a negative electrode active material, a thickener, and an aqueous solvent (aqueous mixed material preparation step S10), (2) Steps for preparing an aqueous solution containing a binder (binder-containing aqueous solution preparation step S20), (3) Steps for adjusting the pH of the binder-containing aqueous solution (pH preparation step S30), (4) pH adjustment to the prepared aqueous mixed material A step of preparing a negative electrode mixture layer forming paste by mixing the later binder-containing aqueous solution (negative electrode mixture layer forming paste preparation step S40). Hereafter, the manufacturing method of the negative electrode including the said process is demonstrated in detail.

  First, an aqueous mixed material is prepared by adding a negative electrode active material and a thickener to an aqueous solvent (for example, water) and kneading (aqueous mixed material preparation step S10). Preferably, a thickener aqueous solution is prepared by adding a thickener in advance to an aqueous solvent (for example, water) and kneading, and a negative electrode active material is added to the prepared thickener aqueous solution and kneaded. To prepare an aqueous mixed material. Next, the pH of the aqueous mixed material at this time is measured using a commercially available pH meter. The pH of the aqueous mixed material is usually about 6 to 9, and preferably about 7 to 8.

Furthermore, in the manufacturing method disclosed here, a binder-containing aqueous solution (including a dispersion) in which a binder is dissolved or dispersed in an aqueous solvent is prepared (binder-containing aqueous solution preparation step S20). And pH of this binder containing aqueous solution is adjusted (pH adjustment process S30). At this time, it is preferable to adjust the pH of the aqueous solution containing binder so that the difference between the pH of the aqueous mixed material and the pH of the aqueous solution containing binder after pH adjustment is within 0.3. More preferably, the difference between the pH of the aqueous mixed material and the pH of the binder-containing aqueous solution after pH adjustment is within 0.2. More preferably, it is within 0.1.
As the method for adjusting the pH, typically, the aqueous solution after adjustment is preferably shifted to the alkaline side than the aqueous solution before adjustment, and a compound that exhibits alkalinity when dissolved in water is appropriately selected. A predetermined amount of an alkaline aqueous solution in which is dissolved is added to the binder-containing aqueous solution to adjust the pH of the binder-containing aqueous solution. Examples of the compound that exhibits alkalinity when dissolved in water include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, lithium carbonate, sodium carbonate, and sodium bicarbonate, or ammonia. Is mentioned. The method for adjusting the pH is not limited to those described above, and if it is desired to shift to the acidic side, a compound that exhibits acidity when dissolved in water can be appropriately selected. Examples thereof include inorganic acids such as sulfuric acid, hydrochloric acid and nitric acid, and organic acids such as acetic acid and carboxylic acid.

Then, by mixing the aqueous mixed material and the pH-adjusted binder-containing aqueous solution, a negative electrode mixture layer forming paste containing all the materials constituting the negative electrode mixture layer is prepared (negative electrode mixture layer forming paste). Preparation step S40). Although not particularly limited, in order to improve the drying efficiency, the solid content of the negative electrode mixture layer forming paste is about 50% to 70% (preferably 52 to 60%, more preferably 53 to 58%). Preferably there is. According to such a procedure, an aqueous mixed material and a binder-containing aqueous solution are prepared (prepared) without simultaneously adding constituent materials for forming the negative electrode mixture layer (negative electrode active material, binder, thickener, etc.), and aqueous mixed Since the difference between the pH of the material and the pH of the binder-containing aqueous solution after pH adjustment is adjusted to be within 0.3, the generation of aggregates during the preparation (kneading) of the negative electrode mixture layer forming paste (The paste is finer and excellent in dispersibility).
Next, the prepared paste for forming a negative electrode mixture layer is passed through a predetermined filter to remove aggregates (filtering step S50). The permeation amount per hour when the paste for forming a negative electrode mixture layer was passed through a filter (62.5-HC-50XB; manufactured by Loki Techno Co., filtration accuracy 50 μm, filter medium length 62.5 μm) was 1 It is preferably 2 g / s or more (preferably 1.5 g / s or more, more preferably 1.8 g / s or more).

Next, the prepared paste for forming the negative electrode mixture layer is applied (coated) on the surface of the negative electrode current collector, the solvent is volatilized and dried, and then compressed (pressed). Thereby, the negative electrode of the lithium ion secondary battery in which the negative electrode mixture layer is formed (held) on the surface of the negative electrode current collector is obtained (negative electrode mixture layer forming step S60). Since such a negative electrode is formed using a paste that is more finely grained and is less finely divided, it can be a negative electrode that is excellent in quality without defects such as coating unevenness.
In addition, as a method of apply | coating the said paste for negative electrode compound material layer formation to a negative electrode collector, the technique similar to a conventionally well-known method is employable suitably. For example, the paste can be suitably applied to the negative electrode current collector by using an appropriate application device such as a slit coater, a die coater, or a gravure coater. Moreover, when drying a solvent, it can dry favorably by using natural drying, a hot air, low-humidity air, a vacuum, infrared rays, far-infrared rays, and an electron beam individually or in combination. Furthermore, as a compression method, a conventionally known compression method such as a roll press method or a flat plate press method can be employed. In adjusting the thickness, the thickness may be measured with a film thickness measuring instrument, and the press pressure may be adjusted to compress a plurality of times until a desired thickness is obtained.

  Next, an embodiment in the case where a lithium ion secondary battery is constructed using the negative electrode will be described. First, a positive electrode, a separator and the like suitable for use in combination with the negative electrode described above will be described. The positive electrode can have the same configuration as before. As the positive electrode current collector constituting such a positive electrode, for example, aluminum or an alloy material mainly composed of aluminum is preferably used. The shape of the positive electrode current collector can be the same as the shape of the negative electrode. Typically, a sheet-like positive electrode current collector made of aluminum is used.

The positive electrode active material contained in the positive electrode mixture layer formed in the positive electrode disclosed herein may be any material that can occlude and release lithium. As a typical positive electrode active material, lithium and at least one kind of positive electrode active material may be used. A composite oxide containing a transition metal element can be given. For example, cobalt lithium composite oxide (LiCoO ₂ ), nickel lithium composite oxide (LiNiO ₂ ), manganese lithium composite oxide (LiMn ₂ O ₄ ), or nickel-cobalt-based LiNi _x Co _1-x O ₂ ( 0 <x <1), cobalt / manganese-based LiCo _x Mn _1-x O ₂ (0 <x <1), nickel / manganese-based LiNi _x Mn _1-x O ₂ (0 <x <1) and LiNi as represented by _{x Mn 2-x O 4 (} 0 <x <2), a so-called binary lithium-containing composite oxide containing two kinds of transition metal elements, or nickel cobalt containing three transition metal elements A ternary lithium-containing composite oxide such as manganese may be used.
Further, an olivine type lithium phosphate represented by the general formula LiMPO ₄ (M is at least one element of Co, Ni, Mn, and Fe; for example, LiFePO ₄ , LiMnPO ₄ ) is used as the positive electrode active material. Also good.

  The conductive material contained in the positive electrode mixture layer formed on the positive electrode disclosed herein is not limited to a specific conductive material as long as it is conventionally used in this type of lithium ion secondary battery. For example, carbon materials such as carbon powder and carbon fiber can be used. As the carbon powder, various carbon blacks (for example, acetylene black, furnace black, ketjen black), graphite powder, and the like can be used. Among these, you may use together 1 type, or 2 or more types.

  The positive electrode mixture layer formed on the positive electrode disclosed herein contains, in addition to the positive electrode active material and the conductive material, one or more materials that can be blended in the negative electrode mixture layer as necessary. Can be made. As such a material, various materials that can function as binders and thickeners as listed as constituent materials of the negative electrode composite material layer can be similarly used.

  The positive electrode disclosed here can be manufactured by a method similar to that of the negative electrode. A paste-like (or slurry-like) composition (hereinafter referred to as a positive electrode mixture layer forming paste) is prepared by dispersing a positive electrode active material and a binder in an appropriate solvent. The prepared paste for forming a positive electrode mixture layer is applied to a positive electrode current collector, dried, and then compressed (pressed) to form the positive electrode current collector and the positive electrode mixture formed on the positive electrode current collector. A positive electrode provided with a layer can be produced.

  Moreover, as a separator used with a positive electrode and a negative electrode, the separator similar to the past can be used. For example, a porous sheet made of resin (a microporous resin sheet) can be preferably used. As a constituent material of such a porous sheet, polyolefin resins such as polyethylene (PE), polypropylene (PP), and polystyrene are preferable. In particular, a porous structure such as a PE sheet, a PP sheet, a two-layer structure sheet in which a PE layer and a PP layer are laminated, and a three-layer structure sheet in which one PE layer is sandwiched between two PP layers. A polyolefin sheet can be suitably used. When a solid electrolyte or a gel electrolyte is used as the electrolyte, a separator may not be necessary (that is, in this case, the electrolyte itself can function as a separator).

As the electrolyte, the same electrolyte as a non-aqueous electrolyte (typically, an electrolytic solution) conventionally used in lithium ion secondary batteries can be used without particular limitation. Such a non-aqueous electrolyte typically has a composition in which a suitable non-aqueous solvent (organic solvent) contains a lithium salt that can function as an electrolyte. As the electrolyte, a lithium salt conventionally used in lithium ion secondary batteries can be appropriately selected and used. Examples of the lithium salt include LiPF ₆ , LiClO ₄ , LiAsF ₆ , Li (CF ₃ SO ₂ ) ₂ N, LiBF ₄ , LiCF ₃ SO _{3 and the} like. Such electrolytes can be used alone or in combination of two or more. A particularly preferred example is LiPF ₆ . Examples of the non-aqueous solvent include carbonates such as ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and propylene carbonate (PC). Such non-aqueous solvents can be used alone or in combination of two or more.

Hereinafter, although one form of a lithium ion secondary battery provided with the negative electrode produced by the said manufacturing method is demonstrated with reference to drawings, it is not intending to limit this invention to this embodiment. That is, as long as the negative electrode according to the present embodiment is employed, the shape (outer shape and size) of the lithium ion secondary battery to be constructed is not particularly limited. In the following embodiment, a rectangular battery will be described.
In addition, in the following drawings, the same code | symbol is attached | subjected to the member and site | part which show | plays the same effect | action, and the overlapping description may be abbreviate | omitted. Moreover, the dimensional relationship (length, width, thickness, etc.) in each drawing does not necessarily reflect the actual dimensional relationship.

FIG. 7 is a perspective view schematically showing a lithium ion secondary battery according to an embodiment. FIG. 8 is a longitudinal sectional view taken along line VIII-VIII in FIG.
As shown in FIGS. 7 and 8, the lithium ion secondary battery 10 according to the present embodiment includes the above-described lithium ion secondary battery constituent materials (active material for each positive and negative electrode, current collector for each positive and negative electrode, separator, etc. ) And a battery case 15 having a rectangular shape (typically a flat rectangular parallelepiped shape) that accommodates the electrode body 50 and a suitable non-aqueous electrolyte (typically an electrolyte). Prepare.

  The case 15 includes a box-shaped case main body 30 in which one of the narrow surfaces in the flat rectangular parallelepiped shape is an opening 20, and the opening 20 is attached (for example, welded) to the opening 20. And a lid 25 for closing. As a material constituting the case 15, the same material as that used in a general lithium ion secondary battery can be used as appropriate, and there is no particular limitation. The case 15 according to the present embodiment is made of, for example, aluminum.

  The lid body 25 is formed in a rectangular shape that matches the shape of the opening 20 of the case body 30. Further, the lid body 25 is provided with a positive terminal 60 and a negative terminal 80 for external connection, respectively, and a part of these terminals 60 and 80 protrudes from the lid body 25 toward the outside of the case 15. It is formed to do. Similarly to the case of the conventional lithium ion secondary battery, the lid 25 is provided with a safety valve 40 for discharging the gas generated inside the case 15 to the outside of the case 15 when the battery is abnormal. . The safety valve 40 can be used without particular limitation as long as the safety valve 40 has a mechanism that opens and discharges gas to the outside of the case 15 when the pressure inside the case 15 rises above a predetermined level.

  As shown in FIG. 8, the lithium ion secondary battery 10 includes a wound electrode body 50 in the same manner as a normal lithium ion secondary battery. The electrode body 50 is accommodated in the case main body 30 in a posture in which the winding axis is laid down (that is, in the direction in which the opening 20 is positioned in the lateral direction with respect to the winding axis). The electrode body 50 includes a positive electrode sheet (positive electrode) 66 in which a positive electrode mixture layer 64 is formed on the surface of a long sheet-like positive electrode current collector 62 and a negative electrode composite on the surface of a long sheet-like negative electrode current collector 82. The negative electrode sheet (negative electrode) 86 on which the material layer 84 is formed is overlapped with the two long separator sheets 100 and wound, and the obtained electrode body 50 is flattened by crushing and ablating from the side surface direction. It is formed into a shape.

  Further, in the wound positive electrode sheet 66, the positive electrode current collector 62 is exposed without forming the positive electrode mixture layer 64 at one end portion along the longitudinal direction, while the negative electrode is wound. Also in the sheet 86, the negative electrode current collector 82 is exposed at one end portion along the longitudinal direction without forming the negative electrode mixture layer 84. A positive electrode terminal 60 is joined to the exposed end of the positive electrode current collector 62, and is electrically connected to the positive electrode sheet 66 of the wound electrode body 50 formed in the flat shape. Similarly, a negative electrode terminal 80 is joined to the exposed end portion of the negative electrode current collector 82 and is electrically connected to the negative electrode sheet 86. The positive and negative electrode terminals 60 and 80 and the positive and negative electrode current collectors 62 and 82 can be joined by, for example, ultrasonic welding, resistance welding, or the like.

  The material and the member itself constituting the wound electrode body 50 having the above-described configuration are other than a negative electrode (here, the negative electrode sheet 86) in which the negative electrode mixture layer disclosed herein is formed on the negative electrode current collector as the negative electrode. The electrode body of a conventional lithium ion secondary battery may be the same as that of the conventional lithium ion secondary battery, and is not particularly limited. The negative electrode sheet 86 and the positive electrode sheet 66 are produced as described above.

The produced positive electrode sheet 66 and negative electrode sheet 86 are stacked together with two separators (for example, porous polyolefin resin) 100 and wound, and the wound electrode body 50 obtained is placed in the case body 30 with its winding shaft lying sideways. Non-aqueous electrolysis such as a mixed solvent of EC and DMC (for example, a mass ratio of 1: 1) containing an appropriate amount of a supporting salt (for example, a lithium salt such as LiPF ₆ ) (for example, a concentration of 1M). After injecting the liquid, the lid body 25 is attached to the opening 20 and sealed (for example, laser welding), whereby the lithium ion secondary battery 10 of the present embodiment can be constructed.

In the manufacturing method according to the first embodiment described above, the pH of the binder-containing aqueous solution is adjusted. However, the method is not limited to this method. Hereinafter, the preferable aspect of the manufacturing method of the negative electrode for lithium ion secondary batteries which concerns on 2nd Embodiment is demonstrated, referring FIG.
As shown in FIG. 2, the manufacturing method according to this embodiment includes a lithium including a negative electrode in which a negative electrode mixture layer including a negative electrode active material, a thickener, and a binder is formed (held) on the surface of a negative electrode current collector. A method for producing an ion secondary battery, comprising: (1) a step of preparing an aqueous solution containing a binder (binder-containing aqueous solution preparation step S110); and (2) mixing at least a negative electrode active material, a thickener, and an aqueous solvent. Preparing an aqueous mixed material (aqueous mixed material preparing step S120), (3) adjusting the pH of the aqueous mixed material (pH adjusting step S130), (4) adding the aqueous mixed material after pH adjustment to the aqueous mixed material A step of preparing a negative electrode mixture layer forming paste by mixing a binder-containing aqueous solution (negative electrode mixture layer forming paste preparation step S140). Hereafter, the manufacturing method of the negative electrode including the said process is demonstrated in detail.

  First, a binder-containing aqueous solution prepared by dissolving or dispersing a binder in an aqueous solvent (for example, water) is prepared (binder-containing aqueous solution preparation step S110). Next, the pH of the binder-containing aqueous solution at this time is measured using a commercially available pH meter. The pH of the binder-containing aqueous solution is usually about 6 to 9, and preferably about 7 to 8.

  Further, in the manufacturing method disclosed herein, an aqueous mixed material is prepared by adding a negative electrode active material and a thickener to an aqueous solvent (for example, water) and kneading (aqueous mixed material preparation step S120). Preferably, a thickener aqueous solution is prepared by adding a thickener in advance to an aqueous solvent (for example, water) and kneading, and a negative electrode active material is added to the prepared thickener aqueous solution and kneaded. To prepare an aqueous mixed material. Then, the pH of the aqueous mixed material is adjusted (pH adjusting step S130). The pH adjustment method is performed by adding the same method as the manufacturing method according to the first embodiment to the aqueous mixed material. At this time, it is preferable to adjust the pH of the aqueous mixed material so that the difference between the pH of the binder-containing aqueous solution and the pH of the aqueous mixed material after pH adjustment is within 0.5. More preferably, the difference between the pH of the aqueous mixed material after pH adjustment and the pH of the binder-containing aqueous solution is within 0.3. More preferably, it is within 0.1.

Then, by mixing the binder-containing aqueous solution and the pH-adjusted aqueous mixed material, a negative electrode mixture layer forming paste containing all the materials constituting the negative electrode mixture layer is prepared (negative electrode mixture layer forming paste). Preparation step S140). Although not particularly limited, in order to improve the drying efficiency, the solid content of the negative electrode mixture layer forming paste is about 50% to 70% (preferably 52% to 60%, more preferably 53% to 58%). ) Is preferable. According to such a procedure, an aqueous mixed material and a binder-containing aqueous solution are prepared (prepared) without simultaneously adding constituent materials (negative electrode active material, binder, thickener, etc.) for forming a negative electrode mixture layer, and a binder is contained. Since the difference between the pH of the aqueous solution and the pH of the aqueous mixed material after pH adjustment is adjusted to within 0.5, aggregates are generated during the preparation (kneading) of the negative electrode mixture layer forming paste. Can be suppressed.
Next, the prepared negative electrode mixture layer forming paste is passed through a predetermined filter to remove aggregates (filtering step S150). The permeation amount per hour when the paste for forming a negative electrode mixture layer was passed through a filter (62.5-HC-50XB; manufactured by Loki Techno Co., filtration accuracy 50 μm, filter medium length 62.5 μm) was 1 It is preferably 2 g / s or more (preferably 1.5 g / s or more, more preferably 1.8 g / s or more).
Next, the prepared paste for forming a negative electrode mixture layer is applied (coated) on the surface of the negative electrode current collector, volatilized and dried, and then compressed (pressed) (negative electrode mixture layer forming step) S160). Thereby, the negative electrode of the lithium ion secondary battery in which the negative electrode mixture layer is formed (held) on the surface of the negative electrode current collector is obtained.

  Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the examples.

<Example 1: Preparation of paste and performance evaluation 1 of the paste>
[Preparation of paste]
<Sample 1>
In a CMC aqueous solution (thickener aqueous solution) obtained by adding 0.8 parts by mass of CMC (thickener) to ion-exchanged water, the average particle size is 9.6 μm, the specific surface area is 4.7 m ² / g, and the tap density is 0. An aqueous mixed material having a solid content of 53% was prepared by adding 100 parts by mass of natural graphite particles (negative electrode active material) of .86 g / cm ³ and kneading with a planetary mixer. When the pH of the aqueous mixed material at this time was measured with a commercially available pH meter, the pH was 7.1.
In addition, a predetermined amount of aqueous sodium hydroxide solution is added to a binder-containing aqueous solution (solid content 48.5%) containing 1 part by mass of SBR (binder) with respect to 100 parts by mass of natural graphite particles, and the binder-containing aqueous solution. The pH of was adjusted to 6.3.
Then, the prepared aqueous mixed material and the binder-containing aqueous solution after pH adjustment are mixed, and ion-exchanged water is further added so that the final solid content is 52%. A paste was prepared.
<Sample 2>
A negative electrode mixture layer forming paste according to Sample 2 was prepared in the same manner as Sample 1, except that the pH of the binder-containing aqueous solution was adjusted to 6.7 and the binder-containing aqueous solution after pH adjustment was used.
<Sample 3>
A negative electrode mixture layer forming paste according to Sample 3 was prepared in the same manner as Sample 1, except that the pH of the binder-containing aqueous solution was adjusted to 7.2 and the binder-containing aqueous solution after pH adjustment was used.
<Sample 4>
A negative electrode mixture layer forming paste according to Sample 4 was prepared in the same manner as Sample 1, except that the pH of the binder-containing aqueous solution was adjusted to 7.6 and the binder-containing aqueous solution after pH adjustment was used.
<Sample 5>
A negative electrode mixture layer forming paste according to Sample 5 was prepared in the same manner as Sample 1, except that the pH of the binder-containing aqueous solution was adjusted to 7.9 and the binder-containing aqueous solution after pH adjustment was used.

[Transmission measurement test]
The negative electrode composite material layer forming paste according to Samples 1 to 5 prepared above is permeated through a filter (62.5-HC-50XB; manufactured by Loki Techno Co., filtration accuracy 50 μm, filter material length 62.5 μm). The amount of permeation was measured. The obtained results are shown in Table 1 and FIG. In addition, the vertical axis | shaft in FIG. 3 represents the permeation amount [g / s] of the paste for negative electrode compound-material layer formation, and a horizontal axis represents pH of the binder containing aqueous solution after pH adjustment.

  As shown in FIG. 3 and Table 1, according to the results of the permeation amount measurement test, the permeation amount was highest when the difference between the pH of the aqueous mixed material and the pH of the binder-containing aqueous solution after pH adjustment was 0.1 (that is, The generation of agglomerates is suppressed, and the paste is finely divided.) When the above difference exceeds 0.3, it is confirmed that the amount of permeation rapidly decreases (that is, a lot of agglomerates are generated). It was.

<Example 2: Preparation of paste and performance evaluation 2 of the paste>
[Preparation of paste]
<Sample 6>
100 parts by mass of natural graphite particles (negative electrode active material) having an average particle diameter of 11.8 μm, a specific surface area of 4.9 m ² / g, and a tap density of 0.93 g / cm ³ , and 1 part by mass of CMC (thickening material) An aqueous mixed material having a solid content of 55% was prepared by adding to ion-exchanged water and kneading with a planetary mixer. When the pH of the aqueous mixed material at this time was measured with a commercially available pH meter, the pH was 7.7.
Further, a predetermined amount of an aqueous sodium hydroxide solution is added to a binder-containing aqueous solution (solid content rate of 48.6%) containing 1 part by mass of SBR with respect to 100 parts by mass of natural graphite particles to adjust the pH of the binder-containing aqueous solution. Adjusted to 6.
Then, the prepared aqueous mixed material and the binder-containing aqueous solution after pH adjustment are mixed, and ion-exchanged water is further added so that the final solid content rate becomes 54%. A paste was prepared.
<Sample 7>
A negative electrode mixture layer forming paste according to Sample 7 was prepared in the same manner as Sample 6, except that the pH of the binder-containing aqueous solution was adjusted to 6.7 and the binder-containing aqueous solution after pH adjustment was used.
<Sample 8>
A negative electrode mixture layer forming paste according to Sample 8 was prepared in the same manner as Sample 6 except that the binder-containing aqueous solution was adjusted to pH 7.2 and the pH-adjusted binder-containing aqueous solution was used.
<Sample 9>
A negative electrode mixture layer forming paste according to Sample 9 was prepared in the same manner as Sample 6 except that the binder-containing aqueous solution was adjusted to pH 7.6 and the pH-adjusted binder-containing aqueous solution was used.
<Sample 10>
A negative electrode mixture layer forming paste according to Sample 10 was prepared in the same manner as Sample 6, except that the pH of the binder-containing aqueous solution was adjusted to 8.1 and the binder-containing aqueous solution after the pH adjustment was used.

[Transmission measurement test]
The negative electrode composite material layer forming paste according to Samples 6 to 10 prepared above is passed through a filter (62.5-HC-50XB; manufactured by Loki Techno Co., filtration accuracy 50 μm, filter material length 62.5 μm), and per unit time. The amount of permeation was measured. The obtained results are shown in Table 2 and FIG. In addition, the vertical axis | shaft in FIG. 4 represents the permeation | transmission amount [g / s] of the paste for negative electrode compound-material layer formation, and a horizontal axis represents pH of the binder containing aqueous solution after pH adjustment.

As shown in FIG. 4 and Table 2, according to the results of the permeation amount measurement test, the permeation amount is the largest when the difference between the pH of the aqueous mixed material and the pH of the binder-containing aqueous solution after pH adjustment is 0.1. It was confirmed that when the difference exceeded 0.2, the amount of permeation rapidly decreased.
From the results of the permeation measurement tests according to Example 1 and Example 2 described above, when adjusting the pH of the binder-containing aqueous solution, the pH of the aqueous mixed material and the pH of the binder-containing aqueous solution after pH adjustment When the difference is within 0.3, the filter permeation amount of the negative electrode mixture layer forming paste is excellent, that is, the generation of aggregates is suppressed (the paste is finer). It was done.

<Example 3: Preparation of paste and performance evaluation 3 of the paste>
[Preparation of paste]
<Sample 11>
In a CMC aqueous solution (thickener aqueous solution) obtained by adding 0.8 parts by mass of CMC (thickener) to ion-exchanged water, the average particle size is 9.6 μm, the specific surface area is 4.7 m ² / g, and the tap density is 0. An aqueous mixed material having a solid content of 53% was prepared by adding 100 parts by mass of natural graphite particles (negative electrode active material) of .86 g / cm ³ and kneading with a planetary mixer. When the pH of the aqueous mixed material at this time was measured with a commercially available pH meter, the pH was 7.1.
Moreover, pH 7.9 formed by adding predetermined amount sodium hydroxide aqueous solution to the binder containing aqueous solution (solid content rate 49.5%) containing 1 mass part SBR (binder) with respect to 100 mass parts of natural graphite particles. A binder-containing aqueous solution was prepared.
Then, the prepared aqueous mixed material and the binder-containing aqueous solution were mixed, and ion-exchanged water was further added so that the final solid content rate was 54% to prepare a negative electrode mixture layer forming paste according to Sample 11. .
<Sample 12>
A predetermined amount of aqueous sodium hydroxide solution was added to the aqueous mixed material according to Sample 11 to adjust the pH of the aqueous mixed material to 7.3. A negative electrode mixture layer forming paste according to Sample 12 was prepared in the same manner as Sample 11, except that the aqueous mixed material after pH adjustment was used.
<Sample 13>
The pH of the aqueous mixed material was adjusted to 7.5. A negative electrode composite layer forming paste according to Sample 13 was prepared in the same manner as Sample 12, except that the pH-adjusted aqueous mixed material was used.
<Sample 14>
The pH of the aqueous mixed material was adjusted to 7.8. A negative electrode mixture layer forming paste according to Sample 14 was prepared in the same manner as Sample 12, except that the aqueous mixed material after pH adjustment was used.
<Sample 15>
The pH of the aqueous mixed material was adjusted to 8.3. A negative electrode mixture layer forming paste according to Sample 15 was prepared in the same manner as Sample 12, except that the pH-adjusted aqueous mixed material was used.

[Transmission measurement test]
The negative electrode composite material layer forming paste according to Samples 11 to 15 prepared above is transmitted through a filter (62.5-HC-50XB; manufactured by Loki Techno Co., Ltd., filtration accuracy 50 μm, filter material length 62.5 μm). The amount of permeation was measured. The obtained results are shown in Table 3 and FIG. In addition, the vertical axis | shaft in FIG. 5 represents the permeation | transmission amount [g / s] of the paste for negative mix layer formation, and a horizontal axis represents pH of the aqueous mixed material after pH adjustment.

  As shown in FIG. 5 and Table 3, according to the results of the permeation amount measurement test, the permeation amount was highest when the difference between the pH of the aqueous mixed material after pH adjustment and the pH of the binder-containing aqueous solution was 0.1, It was confirmed that when the difference exceeds 0.5, the amount of transmission decreases rapidly.

<Example 4: Preparation of paste and performance evaluation 4 of the paste>
[Preparation of paste]
<Sample 16>
100 parts by mass of natural graphite particles (negative electrode active material) having an average particle diameter of 12 μm, a specific surface area of 4.2 m ² / g and a tap density of 0.83 g / cm ³ and 1 part by mass of CMC (thickening material) are subjected to ion exchange. An aqueous mixed material having a solid content of 53% was prepared by adding to water and kneading with a planetary mixer. When the pH of the aqueous mixed material at this time was measured with a commercially available pH meter, the pH was 6.7.
Moreover, binder containing pH 7.2 formed by adding a predetermined amount of sodium hydroxide aqueous solution to binder containing aqueous solution (solid content rate 49.3%) containing 1 part by weight of SBR with respect to 100 parts by weight of natural graphite particles. An aqueous solution was prepared.
Then, the prepared aqueous mixed material and the binder-containing aqueous solution were mixed, and ion-exchanged water was added so that the final solid content rate was 52% to prepare a negative electrode mixture layer forming paste according to sample 16. .
<Sample 17>
A predetermined amount of aqueous sodium carbonate solution was added to the aqueous mixed material according to Sample 16 to adjust the pH of the aqueous mixed material to 7.2. A negative electrode mixture layer forming paste according to Sample 17 was prepared in the same manner as Sample 16, except that the aqueous mixed material after pH adjustment was used.
<Sample 18>
The pH of the aqueous mixed material was adjusted to 7.5. A negative electrode mixture layer forming paste according to Sample 18 was prepared in the same manner as Sample 17, except that the pH-adjusted aqueous mixed material was used.
<Sample 19>
The pH of the aqueous mixed material was adjusted to 7.7. A negative electrode mixture layer forming paste according to Sample 19 was prepared in the same manner as Sample 17, except that the pH-adjusted aqueous mixed material was used.
<Sample 20>
The pH of the aqueous mixed material was adjusted to 8.3. A negative electrode mixture layer forming paste according to Sample 20 was prepared in the same manner as Sample 17 except that the pH-adjusted aqueous mixed material was used.

[Transmission measurement test]
The negative electrode composite material layer forming paste according to Samples 16 to 20 prepared above was permeated through a filter (62.5-HC-50XB; manufactured by Loki Techno Co., filtration accuracy 50 μm, filter material length 62.5 μm), The amount of permeation was measured. The obtained results are shown in Table 4 and FIG. In addition, the vertical axis | shaft in FIG. 6 represents the permeation | transmission amount [g / s] of the paste for negative mix layer formation, and a horizontal axis represents pH of the aqueous mixed material after pH adjustment.

As shown in FIG. 6 and Table 4, according to the result of the permeation measurement test, when the difference between the pH of the aqueous mixed material after pH adjustment and the pH of the binder-containing aqueous solution is 0 (that is, the same pH), the permeation amount is the highest. In many cases, it was confirmed that the amount of permeation rapidly decreased when the difference exceeded 0.5.
From the results of the permeation amount measurement tests according to Example 3 and Example 4 described above, when adjusting the pH of the aqueous mixed material, the pH of the aqueous mixed material after pH adjustment and the pH of the binder-containing aqueous solution When the difference was within 0.5, it was shown that the filter permeation amount of the paste for forming the negative electrode mixture layer was excellent, that is, the generation of aggregates was suppressed.

  As mentioned above, although the specific example of this invention was demonstrated in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

  Since the electrode according to the present invention is produced using a paste that has been made finer by suppressing the generation of aggregates, it can be a high-quality electrode with reduced reaction unevenness. Due to such characteristics, a secondary battery (for example, a lithium ion secondary battery) including the electrode according to the present invention can be suitably used as a power source for a motor (electric motor) mounted on a vehicle such as an automobile. Therefore, according to the present invention, as shown in FIG. 9, the lithium ion secondary battery 10 (which may be in the form of an assembled battery formed by connecting a plurality of the batteries 10 in series) is provided as a power source. A vehicle 1 (typically, an automobile including an electric motor such as an automobile, particularly a hybrid automobile or an electric automobile) can be provided.

DESCRIPTION OF SYMBOLS 1 Vehicle 10 Lithium ion secondary battery 15 Battery case 20 Opening part 25 Cover body 30 Case main body 40 Safety valve 50 Winding electrode body 60 Positive electrode terminal 62 Positive electrode current collector 64 Positive electrode mixture layer 66 Positive electrode sheet (positive electrode)
80 Negative electrode terminal 82 Negative electrode current collector 84 Negative electrode mixture layer 86 Negative electrode sheet 100 Separator sheet

Claims (12)

A method for producing an electrode for a secondary battery having a configuration in which a composite material layer including an active material, a thickening material, and a binder is held by a current collector,
Preparing an aqueous mixed material formed by mixing at least the active material, the thickener, and an aqueous solvent;
Preparing an aqueous solution containing the binder and adjusting the pH of the aqueous solution containing the binder;
Preparing a paste for forming a mixture layer by mixing the aqueous solution containing the binder-containing aqueous solution after pH adjustment;
Including
Here, the method for producing an electrode for a secondary battery, wherein the pH of the binder-containing aqueous solution is adjusted so that the difference between the pH of the aqueous mixed material and the pH of the binder-containing aqueous solution after the pH adjustment is within 0.3 .   The manufacturing method according to claim 1, wherein the aqueous mixed material is prepared by adding a predetermined amount of the active material to a thickener solution obtained by mixing the thickener and the aqueous solvent in advance. Method.   The manufacturing method according to claim 1, wherein the active material is a carbon material.   The manufacturing method of Claim 3 whose pH of the said aqueous mixed material is 7-8.   The pH of the binder-containing aqueous solution is adjusted so that the amount of permeation of the paste is at least 1.2 g / s when the mixture layer forming paste is passed through a predetermined filter. The production method according to item. A method for producing an electrode for a secondary battery having a configuration in which a composite material layer including an active material, a thickening material, and a binder is held by a current collector,
Preparing an aqueous mixed material formed by mixing at least the active material, the thickener, and an aqueous solvent, and adjusting the pH of the aqueous mixed material;
Preparing an aqueous solution containing the binder;
Mixing the binder-containing aqueous solution with the pH-adjusted aqueous mixed material to prepare a mixture layer forming paste,
Including
Here, the method for producing an electrode for a secondary battery, wherein the pH of the aqueous mixed material is adjusted so that a difference between the pH of the aqueous mixed material after pH adjustment and the pH of the binder-containing aqueous solution is within 0.5.   The manufacturing method according to claim 6, wherein the aqueous mixed material is prepared by adding a predetermined amount of the active material to a thickener solution obtained by mixing the thickener and the aqueous solvent in advance. Method.   The manufacturing method according to claim 6, wherein the active material is a carbon material.   The manufacturing method of Claim 8 whose pH of the said binder containing aqueous solution is 7-8.   10. The pH of the aqueous mixed material is adjusted so that the amount of permeation of the paste is at least 1.2 g / s when the paste for forming a composite layer is passed through a predetermined filter. The production method according to item.   A secondary battery provided with the electrode for secondary batteries obtained by the manufacturing method in any one of Claim 1 to 10.   A vehicle comprising the secondary battery according to claim 11.

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