JP2014212030A - Electrode for electricity storage device and method for producing the same, and electricity storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode for an electricity storage device, capable of effectively suppressing corrosion of a collector and fabricating an electricity storage device having high battery capacity and excellent battery characteristics, and a method for producing the electrode for an electricity storage device.SOLUTION: In a method for producing an electrode for an electricity storage device according to the present invention, an electrode for an electricity storage device including a stainless collector and an active material layer formed on a surface of the stainless collector is produced. The method includes: a first step of preparing a slurry for an electricity storage device electrode, the slurry containing conductive assistant particles and active material particles and having a pH of 9-12; and a second step of coating the slurry for an electricity storage device electrode on a surface of the stainless collector to be dried, thereby forming the active material layer.

Description

  The present invention relates to an electrode for an electricity storage device, a method for manufacturing the electrode, and an electricity storage device including the electrode.

  In recent years, a power storage device having a high voltage and a high energy density has been required as a power source for driving electronic devices. As such an electricity storage device, a lithium ion battery, a lithium ion capacitor, and the like are expected. The electrode used for such an electricity storage device is usually applied to the surface of the current collector by applying a composition containing an active material, a polymer that functions as a binder, and a conductive additive (slurry for an electricity storage device electrode) to the surface of the current collector. It is manufactured by doing.

  The slurry for an electricity storage device electrode preferably uses water as a liquid medium from the viewpoint of production cost, process safety, and environmental load. For example, in Patent Document 1, a positive electrode plate manufactured by preparing a paste containing water as an active material, a conductive additive, a binder, and a liquid medium, and applying and drying the paste on a positive electrode current collector is manufactured. A method is disclosed. Patent Document 2 discloses that the characteristics of an electricity storage device such as a lithium ion secondary battery or a lithium ion capacitor can be improved by using a lithium-containing nickel composite oxide as a positive electrode active material.

  On the other hand, as an active material, studies are being made to use a material having a large lithium occlusion amount from the viewpoint of achieving the demand for higher output and higher energy density of an electricity storage device. For example, an approach to improve the lithium occlusion amount by using graphite having higher crystallinity as an active material and to realize a capacity close to the theoretical occlusion amount (about 370 mAh / g) of the carbon material is being advanced. . In addition, studies have been made to utilize a silicon material having a maximum lithium occlusion amount of about 4,200 mAh / g as an active material (see, for example, Patent Document 3). In any case, it is considered that the capacity of the electricity storage device is greatly improved by utilizing such an active material having a large lithium storage amount.

  However, an active material using such a material having a large amount of lithium storage is accompanied by a large volume change due to the storage and release of lithium. For this reason, when an aluminum foil or copper foil conventionally used as a current collector is applied to such a material having a large lithium storage capacity, the aluminum foil or copper foil mechanically resists stress due to volume change. Cannot be generated, and “wrinkles” occur in the electrodes. When such “wrinkles” occur, the distance between the electrodes becomes non-uniform, and stable charging / discharging becomes impossible, and the laminated structure of the electrode and separator of the electricity storage device is disturbed and there is a risk of ignition due to a short circuit.

  In order to solve such a problem, studies have been made to use, as a current collector, a stainless steel foil having a mechanical strength superior to that of a conventional current collector (see, for example, Patent Documents 4 and 5).

JP 2006-302553 A JP 2008-13405 A JP 2004-185810 A JP 2008-108741 A JP 2010-33782 A

  However, the stainless steel foil forms a very thin passive film on its surface that bears corrosion resistance. This passive film is a major obstacle to ensuring good electrical conductivity. For this reason, in the technique using the stainless steel foil as described in Patent Document 4 and Patent Document 5 as the current collector, the passive film on the surface of the stainless steel foil increases the electrode resistance. The property could not be achieved.

  Further, a lithium-containing nickel composite oxide described in Patent Document 2, which is promising as an active material for improving the characteristics of an electricity storage device such as a lithium ion secondary battery or a lithium ion capacitor, is used in water. On the other hand, it was unstable and tended to be altered by mixing with water. Furthermore, the lithium-containing nickel composite oxide tends to be easily hydrolyzed. As the lithium-containing nickel composite oxide is hydrolyzed, the pH of the electricity storage device electrode slurry increases with time, and as a result, the current collector such as aluminum is corroded to increase the electrode resistance. . When an electricity storage device is produced using such a slurry for electricity storage device electrodes, the characteristics inherent to the lithium-containing nickel composite oxide may not be sufficiently exhibited.

  Accordingly, some aspects of the present invention provide a power storage device that can effectively suppress the corrosion of the current collector and can produce a power storage device that has a high battery capacity and excellent battery characteristics by solving the above problems. An electrode for a device and a manufacturing method thereof are provided.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
One aspect of the method for producing an electrode for an electricity storage device according to the present invention is as follows:
A method for producing an electrode for an electricity storage device comprising a stainless steel current collector and an active material layer formed on a surface of the stainless steel current collector,
A first step of preparing a slurry for an electricity storage device electrode containing conductive auxiliary particles and active material particles and having a pH of 9 to 12;
A second step of forming the active material layer by applying and drying the slurry for the electricity storage device electrode on the surface of the stainless steel current collector;
It is characterized by including.

[Application Example 2]
In the method for manufacturing the electrode for an electricity storage device of Application Example 1,
The active material particles may be lithium-containing nickel (composite) oxide particles.

[Application Example 3]
In the manufacturing method of the electrode for an electricity storage device of Application Example 1 or Application Example 2,
The electrode for the electricity storage device may be a positive electrode.

[Application Example 4]
In the method for manufacturing an electrode for an electricity storage device according to any one of Application Examples 1 to 3,
In the second step, when the thickness of the stainless steel current collector is At (μm) and the thickness of the active material layer is Bt (μm), the relationship of 1 <Bt / At <50 is satisfied. The said slurry for electrical storage device electrodes can be apply | coated to the surface of a stainless steel electrical power collector.

[Application Example 5]
In the method for manufacturing an electrode for an electricity storage device of Application Example 4,
The stainless steel current collector may have a thickness At of 1 to 50 μm.

[Application Example 6]
In the method for manufacturing the electrode for an electricity storage device of Application Example 4 or Application Example 5,
The active material layer may have a thickness Bt of 20 to 200 μm.

[Application Example 7]
In the method for manufacturing an electrode for an electricity storage device according to any one of Application Examples 1 to 6,
When the surface roughness of the stainless steel current collector is Ra (μm) and the average particle diameter of the conductive auxiliary agent particles is D (μm), the relationship of D <Ra can be satisfied.

[Application Example 8]
In the method for manufacturing an electrode for an electricity storage device of Application Example 7,
The stainless steel current collector may have a surface roughness Ra of 0.03 to 1 μm.

[Application Example 9]
In the method for manufacturing the electrode for an electricity storage device of Application Example 7 or Application Example 8,
The conductive auxiliary agent particles may have an average particle diameter D of 0.01 to 0.1 μm.

[Application Example 10]
One aspect of the electrode for an electricity storage device according to the present invention is:
It is manufactured by the method for manufacturing an electrode for an electricity storage device according to any one of Application Examples 1 to 9.

[Application Example 11]
One aspect of the electricity storage device according to the present invention is:
The power storage device electrode of Application Example 10 is provided.

  According to the method for producing an electrode for an electricity storage device according to the present invention, an electrode for an electricity storage device capable of effectively suppressing corrosion of a current collector and producing an electricity storage device having high battery capacity and excellent battery characteristics is produced. can do.

Explanatory drawing which shows typically the effect | action of the electrode for electrical storage devices which concerns on this Embodiment. Explanatory drawing which shows typically the effect | action of the conventional electrode for electrical storage devices. Sectional drawing which shows typically the electrode for electrical storage devices which concerns on this Embodiment. Sectional drawing which shows typically the electrode for electrical storage devices which concerns on this Embodiment.

Hereinafter, preferred embodiments according to the present invention will be described in detail. It should be understood that the present invention is not limited only to the embodiments described below, and includes various modifications that are implemented within a scope that does not change the gist of the present invention. In the present specification, “(meth) acrylic acid” is a concept encompassing both “acrylic acid” and “methacrylic acid”. Further, “˜ (meth) acrylate” is a concept encompassing both “˜acrylate” and “˜methacrylate”.

1. Method for manufacturing electrode for power storage device An electrode for power storage device comprising a stainless steel current collector and an active material layer formed on the surface of the stainless steel current collector is a method for manufacturing an electrode for power storage device according to the present embodiment. A first step of preparing a slurry for an electricity storage device electrode containing conductive auxiliary agent particles and active material particles and having a pH of 9 to 12, and the surface of the stainless steel current collector And a second step of forming the active material layer by applying and drying the slurry for the electricity storage device electrode. Hereafter, each process in the manufacturing method of the electrode for electrical storage devices which concerns on this Embodiment is demonstrated in detail.

1.1. First Step First, in the first step, an electricity storage device electrode slurry is prepared. The slurry for an electricity storage device electrode refers to a dispersion used for forming an active material layer on the surface of a stainless steel current collector. The slurry for an electricity storage device electrode contains conductive auxiliary agent particles and active material particles, and may contain a binder and other components as necessary. Hereinafter, each material contained in the slurry for the electricity storage device electrode will be described.

1.1.1. Conductive Auxiliary Particles The conductive auxiliary particles may be any electron conductive material that does not cause a chemical change in a configured battery. Specific examples include natural graphite such as scaly graphite, scaly graphite, earthy graphite, high-temperature fired bodies such as petroleum coke, coal coke, celluloses, saccharides and mesophase pitch, and graphite such as artificial graphite such as vapor-grown graphite. , Carbon blacks such as acetylene black, furnace black, ketjen black, channel black, lamp black, thermal black, etc., carbon materials such as asphalt pitch, coal tar, activated carbon, mesofuse pitch, polyacene, conductivity of metal fibers, etc. Examples thereof include fibers, metal powders such as copper, nickel, aluminum, and silver, conductive whiskers such as zinc oxide and potassium titanate, and conductive metal oxides such as titanium oxide. It is preferable to use a graphite plate having an aspect ratio of 5 or more. Of these, graphite and carbon black are preferred. Examples of the carbon black include acetylene black, Denka black, and Ketjen black (trade names manufactured by Denki Kagaku Kogyo Co., Ltd. and Lion Corporation).

  The average particle diameter D (μm) of the conductive assistant particles is preferably 0.01 to 0.1 μm, and more preferably 0.02 to 0.05 μm. The average particle diameter D (μm) of the conductive auxiliary particles is the average primary particle diameter of the conductive auxiliary particles. The average primary particle diameter of such conductive additive particles can be measured and calculated by a general method. For example, it can be measured from a transmission electron microscope image. Specifically, conductive auxiliary particles such as carbon black have a structure in which spheres are arranged in a daisy chain. In such a case, it is assumed that one particle connected in a chain is spherical. The diameter can be measured (100 to 1000 pickups), and the average primary particle diameter can be measured from the distribution.

  In this invention, it is preferable that the average particle diameter D (micrometer) of the said conductive support agent particle and the surface roughness Ra (micrometer) of the below-mentioned stainless steel electrical power collector have the relationship of D <Ra. By having such a relationship, the adhesion between the stainless steel current collector and the active material layer is excellent, and charge / discharge rate characteristics, which is one of electrical characteristics, are improved. This technical significance will be described with reference to the drawings.

  FIG. 1 is an explanatory diagram schematically illustrating the operation of the electrode for an electricity storage device according to the present embodiment, and FIG. 2 is an explanatory diagram schematically illustrating the operation of the electrode for an energy storage device according to the related art. The power storage device electrode in FIG. 1 has a relationship of D <Ra, and the power storage device electrode in FIG. 2 has a relationship of D> Ra.

  As shown in FIG. 1, when D <Ra, the conductive auxiliary agent particles 30a easily enter the concave portions on the surface of the stainless steel current collector 10a, and the conductive auxiliary agent particles 30a are arranged so as to fill the concave portions. Can. As a result, the inner surface of the concave portion of the stainless steel current collector 10a can be used as a conductive path. Therefore, the electrode for the electricity storage device according to the present embodiment increases the electrode resistance due to the passive film on the surface of the stainless steel current collector, while efficiently conducting the internal surface of the recess on the surface of the stainless steel current collector 10a. Can be used as Thus, it is considered that by increasing the number of conductive paths, the electrode for an electricity storage device of the present invention can reduce electrode resistance and achieve good charge / discharge characteristics. Further, the conductive auxiliary agent particles 30a easily enter the concave portions on the surface of the stainless steel current collector 10a, and the conductive auxiliary agent particles 30a are arranged so as to fill the concave portions. It is considered that the adhesion between the active material layer 20a and the active material layer 20a can be further improved.

  On the other hand, as shown in FIG. 2, when D> Ra, the conductive auxiliary agent particles 30b cannot easily enter the recesses on the surface of the stainless steel current collector 10b. As a result, it becomes difficult to utilize the inner surface of the concave portion of the stainless steel current collector 10b as a conductive path. Therefore, it is considered that the electrode resistance increases due to the passive film on the surface of the stainless steel current collector as in the prior art, and an electrode capable of achieving good charge / discharge characteristics cannot be obtained. Moreover, in the electrode for electrical storage devices as shown in FIG. 2, the anchor effect as described above cannot be expected, and it is considered that the adhesion between the stainless steel current collector 10b and the active material layer 20b cannot be improved.

  The content of the conductive auxiliary agent particles in the electricity storage device electrode slurry is preferably 20 parts by mass or less, more preferably 1 to 15 parts by mass, with respect to 100 parts by mass of the active material particles. 10 parts by mass is particularly preferred.

1.1.2. Active material particles Examples of the active material particles include carbon materials, silicon materials, oxides containing lithium atoms, lead compounds, tin compounds, arsenic compounds, antimony compounds, aluminum compounds, polyacene, and other conductive polymers; A _X B _Y O _Z (where A is an alkali metal or transition metal, B is at least one selected from transition metals such as cobalt, nickel, aluminum, tin and manganese, O represents an oxygen atom, and X, Y and Z are respectively 1.10>X> 0.05, 4.00>Y> 0.85, and 5.00>Z> 1.5. Examples of such particles are particles.

  Examples of the carbon material include amorphous carbon, graphite, natural graphite, mesocarbon microbeads (MCMB), and pitch-based carbon fibers.

Examples of the silicon material, for example silicon simple substance, silicon oxide, addition and the like silicon alloy, for example _{SiC, SiO x C y (0} <x ≦ 3,0 <y ≦ 5), Si 3 N 4, Si oxide composite represented by Si ₂ N ₂ O, SiO _x (0 <x ≦ 2) (for example, materials described in JP-A No. 2004-185810 and JP-A No. 2005-259697) The silicon material described in JP-A-2004-185810 can be used. The silicon oxide is preferably a silicon oxide represented by the composition formula SiO _x (0 <x <2, preferably 0.1 ≦ x ≦ 1). The silicon alloy is at least one selected from the group consisting of silicon and titanium, zirconium, nickel, copper, iron and molybdenum.
Alloys with certain transition metals are preferred. These transition metal silicon alloys are preferably used because they have high electronic conductivity and high strength. In addition, when the active material particles contain these transition metals, the transition metal present on the surface of the active material particles is oxidized and becomes an oxide having a hydroxyl group on the surface, so that the binding force with the binder becomes better. This is also preferable. As the silicon alloy, it is more preferable to use a silicon-nickel alloy or a silicon-titanium alloy, and it is particularly preferable to use a silicon-titanium alloy. The silicon content in the silicon alloy is preferably 10 mol% or more, and more preferably 20 to 70 mol%, based on all the metal elements in the alloy. Note that the silicon material may be single crystal, polycrystalline, or amorphous.

Examples of the oxide containing lithium atoms include lithium cobaltate, lithium nickelate, lithium manganate, ternary nickel cobalt lithium manganate, LiFePO ₄ , LiCoPO ₄ , LiMnPO ₄ , Li _0.90 Ti _0.05 Nb _0.05 Fe _0.30 Co _0.30 Mn _0.30 PO ₄ , Li (Ni _0.8 Co _0.15 Al _0.05 ) _0.99 B _0.01 O _{2 and the} like.

  The slurry for an electricity storage device electrode manufactured in the first step can be used when producing either an electrode for an electricity storage device of a positive electrode or a negative electrode. In the case of producing a positive electrode, from the viewpoint of improving the charge / discharge characteristics of the electricity storage device, it is preferable to use oxide particles containing lithium atoms among the active material particles exemplified above, and lithium-containing nickel (composite) oxidation. More preferably, product particles are used. In addition, when lithium-containing nickel (composite) oxide particles are used, it hydrolyzes in an aqueous medium, so that the pH of the slurry for an electricity storage device electrode is 9 to 9 without particularly adding a pH adjuster. 12 can be adjusted.

  When producing a negative electrode, it is preferable that the active material particle illustrated above contains a silicon material. Since the silicon material has a large amount of occlusion of lithium per unit weight compared to other active materials, the active material particles can contain the silicon material to increase the storage capacity of the resulting electricity storage device. As a result, the output and energy density of the electricity storage device can be increased.

  Further, since the silicon material has a large amount of lithium occlusion, a large volume change is caused by the occlusion / release of lithium. When stress due to the volume change of the active material due to this charging / discharging is applied to the current collector, the current collector is distorted, resulting in “wrinkles” in the current collector. Easy to deteriorate. However, when the active material particles containing a silicon material are applied to the electrode for an electricity storage device according to the present embodiment, the stainless steel current collector can resist such distortion, so that “wrinkles” are generated. Therefore, good charge / discharge characteristics are easily obtained.

  In addition, when producing a negative electrode, it is more preferable to use the active material particle which consists of a mixture of a silicon material and a carbon material. Since the carbon material has a small volume change due to charge / discharge, the use of a mixture of the silicon material and the carbon material as the negative electrode active material can alleviate the influence of the volume change of the silicon material, and the active material layer And the current collector can be further improved. As such a mixture, a carbon-coated silicon material in which a carbon material film is formed on the surface of the silicon material can also be used. By using a carbon-coated silicon material, the effect of volume change associated with charging / discharging of the silicon material can be effectively mitigated by the carbon material existing on the surface, so that the active material layer and the current collector It becomes easy to improve adhesion.

  When the silicon material is contained as the active material particles, the proportion of the silicon material in 100% by mass of the active material particles is preferably 1% by mass or more, more preferably 1 to 50% by mass, It is more preferable to set it as 5-45 mass%, and it is especially preferable to set it as 10-40 mass%.

  When a silicon material and a carbon material are used in combination as the active material particles, the proportion of the silicon material in 100% by mass of the active material particles is 4 to 40% by mass from the viewpoint of maintaining sufficient binding properties. It is preferably 5 to 35% by mass.

  The average particle diameter of the active material particles is preferably 0.1 to 100 μm, and more preferably 1 to 20 μm.

  Here, the average particle diameter of the active material particles is a volume average particle diameter calculated from the particle size distribution obtained by measuring the particle size distribution using a particle size distribution measuring apparatus based on a laser diffraction method. Examples of such a laser diffraction particle size distribution measuring apparatus include HORIBA LA-300 series, HORIBA LA-920 series (manufactured by Horiba, Ltd.) and the like. This particle size distribution measuring apparatus does not only evaluate the primary particles of the active material particles, but also evaluates secondary particles formed by aggregation of the primary particles. Therefore, the average particle diameter obtained by this particle size distribution measuring apparatus can be used as an indicator of the dispersion state of the active material particles contained in the slurry for the electricity storage device electrode. The average particle diameter of the active material particles is determined by centrifuging the slurry for the electricity storage device electrode to settle the active material particles, then removing the supernatant, and measuring the precipitated active material particles by the above method. Can also be measured.

  The content ratio of the active material particles in the electricity storage device electrode slurry is not particularly limited as long as the above-described relationship of the content ratio of the conductive additive particles and the active material particles is satisfied, but will be described later with respect to 100 parts by mass of the active material particles. It is preferable to use it at a ratio such that the content ratio of the binder is 0.1 to 25 parts by mass, and it is more preferable to use it at a ratio such that it is 0.5 to 15 parts by mass. By setting it as such a usage rate, it is possible to produce an electrode that is excellent in adhesiveness and has low electrode resistance and excellent charge / discharge characteristics.

1.1.3. Binder The power storage device electrode slurry preferably contains a binder. By containing a binder, the adhesion between the conductive auxiliary particles, the active material particles, and the conductive auxiliary agent particles and the active material particles is improved, and the adhesion between the stainless steel current collector and the active material layer is improved. The improvement effect can be expected. Further, by adding a binder to the slurry for the electricity storage device electrode, the coating property is improved, and a good active material layer can be formed on the surface of the stainless steel current collector. Examples of such a binder include polysaccharides, thermoplastic resins, and polymers having rubber elasticity. Preferred binders include starch, carboxymethyl cellulose, cellulose, diacetyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, sodium alginate, polyacrylic acid, polyacrylic acid Na, polyvinyl phenol, polyvinyl methyl ether, polyvinyl alcohol, polyvinyl pyrrolidone, poly Water-soluble polymers such as acrylamide, polyhydroxy (meth) acrylate, styrene-maleic acid copolymer, polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-tetra Fluoroethylene-hexafluoropropylene copolymer, polyethylene, polypropylene, ethylene (Meth) acrylic acid ester copolymer containing (meth) acrylic acid ester such as propylene-diene terpolymer (EPDM), sulfonated EPDM, polyvinyl acetal resin, methyl methacrylate, 2-ethylhexyl acrylate, (meth) acrylic Acid ester-acrylonitrile copolymer, polyvinyl ester copolymer containing vinyl ester such as vinyl acetate, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, polybutadiene, neoprene rubber, fluororubber, polyethylene oxide, polyester polyurethane Resin, polyether polyurethane resin, polycarbonate polyurethane resin, polyester resin, phenol resin, epoxy resin emulsion (latex) or suspense It can be mentioned John. Among these, polyacrylate ester latex, carboxymethyl cellulose, polytetrafluoroethylene, polyvinylidene fluoride, and the like can be preferably used, and acrylic polymers and diene heavy polymers described in Japanese Patent No. 5077613 can be used. The coalescence can be particularly preferably used.

  These binders are preferably used as a dispersion in which the binder is dispersed in the form of particles, more preferably those having an average particle diameter of 0.01 to 5 μm in the dispersion, and 0.05 to 1 μm. It is particularly preferable to use one. Even when a binder dispersed in the form of particles is used, it is considered that the slurry for the electricity storage device electrode is applied to the stainless steel current collector and deformed at the stage of preparing the active material layer by drying, and adsorbed on the active material particles, It is considered that the conductive auxiliary agent particles do not hinder the action of diffusing into the recesses on the surface of the stainless steel current collector.

  The binders exemplified above can be used singly or in combination. The content ratio of the binder in the slurry for the electricity storage device electrode is preferably 0.1 to 25 parts by mass with respect to 100 parts by mass of the active material particles, and 0.5 to 15 parts by mass It is more preferable to use in such a ratio. By setting it as such a usage rate, it is possible to produce an electrode that is excellent in adhesiveness and has low electrode resistance and excellent charge / discharge characteristics.

1.1.4. Other Components The slurry for the electricity storage device electrode may contain a preservative. Such preservatives include 1,2-benzisothiazolin-3-one, 2-methyl-4,5-trimethylene-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 5 -Chloro-2-methyl-4-isothiazolin-3-one, Nn-butyl-1,2-benzisothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 4,5- Examples include dichloro-2-n-octyl-4-isothiazolin-3-one, and one or more of these can be used.

  The slurry for an electricity storage device electrode may contain a liquid medium. Such a liquid medium is preferably an aqueous medium containing water. The aqueous medium can contain a non-aqueous medium other than water. Examples of such a non-aqueous medium include amide compounds, hydrocarbons, alcohols, ketones, esters, amine compounds, lactones, sulfoxides, sulfone compounds, and the like, and one or more selected from these are used. be able to. By using the above aqueous medium as the liquid medium, the electricity storage device electrode slurry has a low degree of adverse effects on the environment, and the safety for handling workers is also increased.

  The content ratio of the non-aqueous medium contained in the aqueous medium is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and substantially no content with respect to 100 parts by mass of the aqueous medium. Is particularly preferred. Here, “substantially does not contain” means that a non-aqueous medium is not intentionally added as a liquid medium, and is inevitably mixed when a slurry for an electricity storage device electrode is produced. May be included.

  The use ratio of the liquid medium in the slurry for the electricity storage device electrode is 30 to 30 in terms of the solid content concentration in the slurry (the ratio of the total mass of components other than the liquid medium in the slurry to the total mass of the slurry; the same applies hereinafter). It is preferable to set it as the ratio used as 70 mass%, and it is more preferable to set it as the ratio used as 40-60 mass%.

1.1.5. pH
The pH value of the slurry for the electricity storage device electrode needs to be 9 to 12, and preferably 9.5 to 11. A known water-soluble acid or base can be used for adjusting the liquid property of the slurry for the electricity storage device electrode. Examples of the acid include hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid; examples of the base include sodium hydroxide, potassium hydroxide, lithium hydroxide, and aqueous ammonia. As described above, when lithium-containing nickel (composite) oxide particles are used as the active material particles, they are hydrolyzed in an aqueous medium, so that it is possible to store electricity even without adding a pH adjuster. The pH of the slurry for device electrodes can be adjusted to 9-12.

  When the pH of the slurry for the electricity storage device electrode is in the range of 9 to 12, the surface of the copper foil or aluminum foil conventionally used as a current collector is corroded, so that a smooth active material layer is formed. It becomes difficult. On the other hand, when the stainless steel foil is used as the current collector, the surface is not etched violently, but the electrical resistance can be reduced by etching the passive film formed on the surface. Conceivable. As a result, the stainless steel foil surface can be efficiently utilized as a conductive path. Thus, it is thought that by increasing the number of conductive paths, the electrical storage device electrode manufactured by the manufacturing method of the present invention can reduce the electrical resistance and achieve good charge / discharge characteristics.

1.1.6. Manufacturing method of slurry for power storage device electrode The slurry for power storage device electrode may be manufactured by any method as long as it contains the above-described components.

  However, from the viewpoint of producing a slurry for an electricity storage device electrode having better dispersibility and stability more efficiently and inexpensively, the conductive auxiliary particles, active material particles and It is preferable to produce by adding optional additive components used as necessary and mixing them. In order to mix the dispersion containing the binder and the other components, it can be carried out by stirring by a known method.

  As the mixing and stirring for producing the slurry for the electricity storage device electrode, a mixer capable of stirring to such an extent that no agglomerates of active material particles remain in the slurry for the electricity storage device electrode and a sufficient dispersion condition as necessary are selected. There is a need to. The degree of dispersion can be measured by a particle gauge, but it is preferable to mix and disperse so that aggregates larger than at least 100 μm are eliminated. Examples of the mixer that meets such conditions include a ball mill, a bead mill, a sand mill, a defoamer, a pigment disperser, a crusher, an ultrasonic disperser, a homogenizer, a planetary mixer, and a Hobart mixer. it can.

The preparation of the slurry for an electricity storage device electrode (mixing operation of each component) is preferably performed at least part of the process under reduced pressure. Thereby, it can prevent that a bubble arises in the active material layer obtained. The degree of pressure reduction is preferably about 5.0 × 10 ^{3 to} 5.0 × 10 ⁵ Pa as an absolute pressure.

1.2. Second Step The second step is a step of forming an active material layer on the surface of the stainless steel current collector by applying the slurry for an electricity storage device electrode to the surface of the stainless steel current collector and drying it. The details of the stainless steel current collector will be described later in “2. Electrode for electricity storage device”.

There is no particular limitation on the method of applying the slurry for the electricity storage device electrode to the surface of the stainless steel current collector. The coating can be performed by an appropriate method such as a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a dipping method, or a brush coating method. The amount of the electricity storage device electrode slurry applied is not particularly limited, but it is preferable that the thickness of the active material layer formed after removing the liquid medium be 0.005 to 5 mm, 0.01 to 2 mm. It is more preferable to set the amount to be.

  The method for drying and removing the liquid medium from the coated film after application is not particularly limited, for example, drying with warm air, hot air, low-humidity air; vacuum drying; (far) drying by irradiation with infrared rays, electron beams, etc. Can do. The drying speed is appropriately set so that the liquid medium can be removed as quickly as possible within a speed range in which the active material layer does not crack due to stress concentration or the active material layer does not peel from the current collector. be able to.

  It is preferable to increase the density of the active material layer by further pressing the coating film after removing the liquid medium. Examples of the pressing method include a mold press and a roll press. The press conditions should be set appropriately depending on the type of press equipment used and the desired density of the active material layer. This condition can be easily set by a few preliminary experiments by those skilled in the art. For example, in the case of a roll press, the linear pressure of the roll press machine is 0.1 to 10 t / cm, preferably 0.5 to 5 t. For example, when the roll temperature is 20 to 100 ° C. at a pressure of 50 cm / cm, the feeding speed of the coating film after removing the liquid medium (rotation speed of the roll) is 1 to 80 m / min, preferably 5 to 50 m / min. it can.

The density of the active material layer after pressing is preferably 1.5 to 4.0 g / cm ³ when the electrode for an electricity storage device is used as a positive electrode, and is 1.7 to 3.8 g / cm ³ . more preferably to; when using an electrode for a power storage device as a negative electrode is preferably in a 1.2~1.9g / cm ^3, more be 1.3~1.8g / cm ³ preferable.

  It is preferable that the pressed coating film is further heated under reduced pressure to completely remove the liquid medium. In this case, the degree of reduced pressure is preferably 50 to 200 Pa, more preferably 75 to 150 Pa as an absolute pressure. As heating temperature, it is preferable to set it as 100-200 degreeC, and it is more preferable to set it as 120-180 degreeC. The heating time is preferably 2 to 12 hours, and more preferably 4 to 8 hours.

  According to the electrode for an electricity storage device manufactured in this way, corrosion of the current collector can be effectively suppressed by using the stainless steel current collector, and the surface of the stainless steel current collector (passive film) is Since the electrical resistance can be reduced by being appropriately etched by the slurry for the electricity storage device electrode, it is possible to produce an electricity storage device having a high battery capacity and excellent battery characteristics.

2. Electric storage device electrode The electric storage device electrode according to the present embodiment is manufactured by the above-described method for manufacturing an electric storage device electrode. Hereinafter, the electrode for an electricity storage device according to the present embodiment will be described in detail with reference to the drawings.

  3 and 4 are cross-sectional views schematically showing one aspect of the electrode for an electricity storage device according to the present embodiment. As shown in FIG. 3, the electrode 100 for an electricity storage device includes a stainless steel current collector 10 and an active material layer 20 formed on the surface of the stainless steel current collector 10. 3, the active material layer 20 is formed only on one surface of the stainless steel current collector 10, but the stainless steel current collector 10 does not have the same structure as the power storage device electrode 200 shown in FIG. 4. The active material layer 20 may be formed on both sides. Moreover, the active material layer 20 may be comprised by 1 layer per single side | surface, and may be comprised from 2 or more layers. Hereinafter, the stainless steel current collector and the active material layer will be described in this order.

2.1. Stainless Steel Current Collector The shape of the stainless steel current collector 10 is not particularly limited, and examples thereof include a foil shape (sheet shape), an expanded metal shape, a punching metal shape, a foam metal shape, and a net shape, but a foil shape (sheet shape). It is preferable that In addition, the thickness of the stainless steel current collector 10 is preferably 1 to 50 μm, more preferably 2 to 40 μm, and particularly preferably 3 to 20 μm.

  The surface roughness Ra of the stainless steel current collector 10 is preferably 0.03 to 1 μm, more preferably 0.04 to 0.5 μm, and particularly preferably 0.04 to 0.1 μm. . When the surface roughness Ra of the stainless steel current collector is in the above range, the adhesion between the active material layer and the stainless steel current collector can be further improved by the anchor effect that the active material layer enters the recess. In addition, the thickness of the active material layer can be made more uniform within the electrode surface, and the uniformity of the storage capacity on the electrode surface can be improved. Furthermore, generation | occurrence | production of cutting | disconnection etc. of metal foil can be suppressed during electrode manufacturing processes, such as coating and a press, and an electrical storage device manufacturing process, such as winding an electrode.

  The surface roughness Ra of the stainless steel current collector in the present invention means “arithmetic average roughness” measured in accordance with JIS B0601-2001.

  The stainless steel current collector 10 can be manufactured by thinning stainless steel or the like. As the stainless steel current collector 10, a thinned one may be used as it is, but a stainless steel current collector whose surface roughness is controlled by physically or chemically treating the surface may be used. Methods for controlling the surface roughness of the stainless steel current collector include methods such as etching treatment (acid treatment, etc.), laser treatment, electrolytic plating, electroless plating, sand blasting, etc., but are not limited to these methods. Is not to be done.

  In addition, the stainless steel used as the raw material of the stainless steel current collector 10 is an Fe—Cr steel containing about 11% or more of chromium and excellent in weather resistance and corrosion resistance. This alloy produces a very thin passive film on its surface in the atmosphere with little subsequent corrosion. Stainless steel is classified into martensite, ferrite, austenite, ferrite-austenite, and semi-austenite according to its metal structure. Austenitic stainless steel belongs to the Fe-Cr-Ni system or Fe-Cr-Mn system and exhibits an austenitic structure, and has high strength and excellent ductility in a wide temperature range from low temperature to high temperature. A solid solution heat treatment rapidly cooled from a temperature of about 1000 degrees Celsius or higher results in a nonmagnetic complete austenite structure, which provides excellent corrosion resistance and maximum ductility. Examples of a preferable composition of stainless steel that can be used in the present invention include JIS standard SUS301, SUS304, SUS316, SUS316L, SUS430, and the like. Particularly preferred is an austenitic stainless steel containing molybdenum such as SUS316 or SUS316L. The content of molybdenum is preferably 1 to 7% by mass, more preferably 1.2 to 6% by mass, and particularly preferably 1.7 to 4% by mass. The nickel content is preferably 8 to 18% by mass, more preferably 9 to 16% by mass, and particularly preferably 10 to 15% by mass. The chromium content is preferably 11 to 26% by mass, more preferably 15 to 20% by mass, and particularly preferably 16 to 19% by mass.

  The stainless steel current collector used in the present invention can be used as an electrode support and a lead terminal.

2.2. Active Material Layer The shape of the active material layer 20 is not particularly limited, but is preferably a layered shape. Moreover, it is preferable that the thickness of the active material layer 20 is 20-200 micrometers. In addition, when the active material layer 20 is a positive electrode active material layer, it is preferable that it is 50-200 micrometers, and when the active material layer 20 is a negative electrode active material layer, it is preferable that it is 30-100 micrometers, More preferably, it is 30-50 micrometers.

  In the electricity storage device electrode according to the present embodiment, when the thickness of the stainless steel current collector is At (μm) and the thickness of the active material layer is Bt (μm), 1 <Bt / At <50 is satisfied. It is preferable. In this case, in the electricity storage device electrode 200 in which the active material layers 20 are formed on both surfaces of the stainless steel current collector 10 as shown in FIG. 4, the thickness Bt of the active material layer is the active material layer formed on one surface. This is the sum of the thickness Bt ′ of the material layer and the thickness Bt ″ of the active material layer formed on the other surface. When the thickness At of the stainless steel current collector and the thickness Bt of the active material layer have a relationship of 1 <Bt / At <50, the charge / discharge characteristics of the electricity storage device become better. Although the expression principle has not been elucidated, the following considerations can be made.

  That is, when the active material layer is thickened, a stress due to the volume change of the active material accompanying charge / discharge is applied to the current collector, and there is a tendency that distortion occurs. Conventional copper foil and aluminum foil cannot sufficiently resist such stress strain due to the low mechanical strength of the material, and the current collector has “wrinkles”. Deterioration of was observed. Such a phenomenon can occur even when stainless steel is used as a current collector. However, when the relationship 1 <Bt / At <50 is established, the stainless steel current collector resists such distortion. It is considered that good charge / discharge characteristics can be generated because generation of “wrinkles” can be effectively suppressed.

3. Electric storage device The electric storage device according to the present embodiment includes the above-described electrode for an electric storage device, further contains an electrolytic solution, and can be manufactured according to a conventional method using components such as a separator. As a specific manufacturing method, for example, a negative electrode and a positive electrode are overlapped via a separator, and this is wound or folded according to the shape of the battery, and stored in a battery container, and an electrolytic solution is injected into the battery container. Can be mentioned. The shape of the battery can be an appropriate shape such as a coin shape, a cylindrical shape, a square shape, or a laminate shape.

  The electrolytic solution may be liquid or gel-like, and an electrolyte that effectively expresses the function as a battery may be selected from known electrolytic solutions used for the electricity storage device according to the type of active material particles. The electrolytic solution can be a solution in which an electrolyte is dissolved in a suitable solvent.

As the electrolyte, in the lithium ion secondary battery, any conventionally known lithium salt can be used. Specific examples thereof include LiClO ₄ , LiBF ₄ , LiPF ₆ , LiCF ₃ CO ₂ , LiAsF. ₆ , LiSbF ₆ , LiB ₁₀ Cl ₁₀ , LiAlCl ₄ , LiCl, LiBr, LiB (C ₂ H ₅ ) ₄ , LiCF ₃ SO ₃ , LiCH ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, and the like can be exemplified lower aliphatic lithium carboxylate.

  The solvent for dissolving the electrolyte is not particularly limited. Specific examples thereof include carbonate compounds such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate; Lactone compounds such as butyl lactone; ether compounds such as trimethoxymethane, 1,2-dimethoxyethane, diethyl ether, 2-ethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran; sulfoxide compounds such as dimethyl sulfoxide, etc. One or more selected from these can be used. The concentration of the electrolyte in the electrolytic solution is preferably 0.5 to 3.0 mol / L, more preferably 0.7 to 2.0 mol / L.

  The electricity storage device according to the present embodiment is covered with an exterior material as necessary. Examples of the exterior material include a heat shrinkable tube, an adhesive tape, a metal film, paper, a cloth, a paint, and a plastic case. Further, at least a part of the exterior may be provided with a portion that changes color by heat so that the heat history during use can be known.

  A plurality of power storage devices according to the present embodiment are housed in a battery pack in series and / or in parallel as necessary. In addition to safety elements such as positive temperature coefficient resistors, thermal fuses, fuses and / or current interrupting elements, the battery pack also requires safety circuits (monitoring the voltage, temperature, current, etc. of each battery and / or the entire battery pack) In this case, a circuit having a function of cutting off current may be provided. In addition to the positive and negative terminals of the entire assembled battery, the battery pack should be provided with the positive and negative terminals of each battery, the entire assembled battery and the temperature detecting terminal of each battery, the current detecting terminal of the entire assembled battery, etc. as external terminals. You can also. The battery pack may incorporate a voltage conversion circuit (such as a DC-DC converter). The connection of each battery may be fixed by welding a lead plate, or may be fixed so that it can be easily attached and detached with a socket or the like. Further, the battery pack may be provided with display functions such as the remaining battery capacity, the presence / absence of charging, and the number of uses.

  The power storage device according to this embodiment can be used for various devices. In particular, video movies, portable video decks with built-in monitors, movie cameras with built-in monitors, digital cameras, compact cameras, single-lens reflex cameras, film with lenses, notebook computers, notebook word processors, electronic notebooks, mobile phones, cordless phones, bearded scorpions, It is preferably used for electric tools, electric mixers, automobiles and the like.

4). EXAMPLES Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. “Part” and “%” in Examples and Comparative Examples are based on mass unless otherwise specified.

  In the following examples, the average particle diameter D of the conductive assistant particles is the diameter of 200 particles observed with a transmission electron microscope (manufactured by Hitachi High-Technologies Corporation, model “H-7650”). Is the value obtained from the distribution. Further, the surface roughness Ra of the stainless steel current collector is a value measured in accordance with JIS B0601-2001.

4.1. Production of binder 4.1.1. Synthesis of binder A In a temperature-controllable autoclave equipped with a stirrer, 300 parts by weight of water, 0.6 parts by weight of sodium dodecylbenzenesulfonate, 1.0 part by weight of potassium persulfate, 0.5 parts by weight of sodium bisulfite, α-methylstyrene dimer 0.2 parts by mass, dodecyl mercaptan 0.2 parts by mass, and polymerization monomer component, 1,3-butadiene 49 parts by mass, styrene 22 parts by mass, methyl methacrylate 4 parts by mass, acrylic 7 parts by mass of acid, 10 parts by mass of itaconic acid, and 8 parts by mass of acrylonitrile were sequentially added, and a polymerization reaction was carried out at 70 ° C. for 8 hours. When 3 hours passed from the start of addition of the polymerization monomer component, 1.0 part by mass of α-methylstyrene dimer and 0.3 part by mass of dodecyl mercaptan were further added. Thereafter, the temperature in the autoclave was raised to 80 ° C., and further reacted for 2 hours to obtain a latex. Thereafter, the pH of the latex was adjusted to 7.0, and 5 parts by mass of sodium tripolyphosphate (added as an aqueous solution having a solid content conversion value and a concentration of 10% by mass) was added. Subsequently, the residual monomer was removed by steam distillation, and the mixture was concentrated under reduced pressure to obtain a binder A (aqueous dispersion) containing 35% by mass of polymer particles. The particle size distribution of the aqueous dispersion obtained above is measured using a particle size distribution measuring apparatus (model “FPAR-1000”, manufactured by Otsuka Electronics Co., Ltd.) using the dynamic light scattering method as a measurement principle, and the particle size distribution is obtained. The average particle diameter (D50) was determined from the result of 220 nm.

4.1.2. Preparation of binder B 80 parts by mass (in terms of solid content) of binder A synthesized above, 20 parts by mass (in terms of solid content) of polyacrylic acid (manufactured by ACROS, product number “185012500”, average molecular weight 240,000), Were mixed and stirred, and water was appropriately added to prepare Binder B having a solid concentration of 35% by mass.

4.2. Synthesis of silicon material (active material particles) Electricity obtained by adjusting the temperature of a mixture of pulverized silicon dioxide powder (average particle size 10 μm) and carbon powder (average particle size 35 μm) to a range of 1,100 to 1,600 ° C. In a furnace, heat treatment is performed for 10 hours under a nitrogen stream (0.5 NL / min), and a silicon oxide powder (average particle diameter) represented by the composition formula SiO _x (x = 0.5 to 1.1) 8 μm) was obtained. 300 g of this silicon oxide powder was charged into a batch-type heating furnace, and the temperature was increased from room temperature (25 ° C.) to 1,100 ° C. at a temperature increase rate of 300 ° C./h while maintaining a reduced pressure of 100 Pa with a vacuum pump. Warm up. Next, while maintaining the pressure in the heating furnace at 2,000 Pa, heat treatment (graphite coating treatment) was performed at 1,100 ° C. for 5 hours while introducing methane gas at a flow rate of 0.5 NL / min. After the completion of the graphite coating treatment, the powder was cooled to room temperature at a temperature decrease rate of 50 ° C./h to obtain about 330 g of graphite-coated silicon oxide powder. This graphite-coated silicon oxide is a conductive powder (active material) in which the surface of silicon oxide is coated with graphite, and its average particle diameter is 10.5 μm. The ratio of the graphite film in the case of mass% was 2 mass%.

4.3. Example 1
4.3.1. Production of electrode for storage device (negative electrode) A thickener (trade name “CMC2200”, manufactured by Daicel Corporation) is added to a biaxial planetary mixer (product name “TK Hibismix 2P-03” manufactured by PRIMIX Corporation). 85 parts by mass (solid content conversion value, added as an aqueous solution having a concentration of 2% by mass), artificial graphite (trade name “MAG”, manufactured by Hitachi Chemical Co., Ltd.), which is highly crystalline graphite as the negative electrode active material 15 parts by mass (solid content converted value) of conductive graphite particles (trade name “Denka Black 75% press product” manufactured by Denki Kagaku Kogyo Co., Ltd.) 1.0 parts by mass and average particle size D = 0.036 μm) and 68 parts by mass of water were added and stirred at 60 rpm for 1 hour. Thereafter, the binder A synthesized above was added in an amount corresponding to 2 parts by mass of the polymer contained therein, and further stirred for 1 hour to obtain a paste. Water is added to the obtained paste, and the solid content concentration is adjusted to 50% by mass. Then, using a stirring defoaming machine (trade name “Netaro Awatori” manufactured by Shinky Co., Ltd.) for 2 minutes at 200 rpm. By stirring and mixing at 1800 rpm for 5 minutes and further under reduced pressure (about 2.5 × 10 ⁴ Pa) at 1800 rpm for 1.5 minutes, a negative electrode power storage device electrode slurry was prepared.

The negative electrode slurry obtained above is uniformly applied to the surface of a 10 μm thick stainless steel foil (surface roughness Ra = 0.06 μm) as a current collector by a doctor blade method so that the film thickness after drying becomes 70 μm. And dried at 60 ° C. for 10 minutes, and then dried at 120 ° C. for 10 minutes. Then, the electrical storage device electrode (negative electrode) was obtained by pressing with a roll-press machine so that the density of an active material layer may be 1.6 g / cm < ³ >.

4.3.2. Production of electricity storage device electrode (positive electrode) A biaxial planetary mixer (product name “TK Hibismix 2P-03” manufactured by PRIMIX Corporation) and an electrochemical device electrode binder (product name “KF Polymer” manufactured by Kureha Co., Ltd.) # 1120 ") 4.0 parts by mass (in terms of solid content), conductive auxiliary agent particles (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name" Denka Black 75% pressed product ", average particle diameter D = 0.036 µm) 0 part by mass, LiNiO ₂ (manufactured by Hayashi Kasei Co., Ltd.) having an average particle size of 10 μm as a positive electrode active material (solid content conversion value) and N-methylpyrrolidone (NMP) 36
A mass part was added, and the mixture was stirred at 60 rpm for 2 hours. After adding NMP to the obtained paste and adjusting the solid content concentration to 65% by mass, the mixture was stirred at 200 rpm for 2 minutes at 200 rpm using a stirring defoaming machine (trade name “Netaro Awatori”). By stirring and mixing at 1,800 rpm for 5 minutes and further under reduced pressure (about 2.5 × 10 ⁴ Pa) at 1,800 rpm for 1.5 minutes, a positive electrode power storage device electrode slurry was prepared. It was 11.0 when pH of the obtained slurry for electrical storage device electrodes was measured in 25 degreeC environment using the pH meter (Horiba Ltd. make, model "LAQUA F-70").

The positive electrode slurry obtained above is applied to the surface of a stainless steel foil (surface roughness Ra = 0.06 μm) having a thickness of 10 μm as a current collector by a doctor blade method so that the film thickness after solvent removal is 190 μm. The solution was uniformly applied and heated at 120 ° C. for 20 minutes to remove the solvent. Then, the electrical storage device electrode (positive electrode) was obtained by pressing with a roll press machine so that the density of an active material layer may be set to 3.0 g / cm < ³ >.

4.3.3. Production and evaluation of electricity storage device (1) Assembly of lithium ion battery cell In the glove box substituted with Ar so that the dew point is -80 ° C or lower, the negative electrode produced above was punched and molded to a diameter of 15.95 mm. It was placed on a two-pole coin cell (trade name “HS Flat Cell” manufactured by Hosen Co., Ltd.). Next, a separator made of a polypropylene porous film punched to a diameter of 24 mm (product name “Celguard # 2400” manufactured by Celgard Co., Ltd.) was placed, and after injecting 500 μL of electrolyte so that air did not enter, A lithium ion battery cell (power storage device) was assembled by placing the positive electrode manufactured in the above-described method by punching and molding the positive electrode to a diameter of 16.16 mm, and sealing the outer body of the bipolar coin cell with a screw. The electrolytic solution used here is a solution obtained by dissolving LiPF ₆ at a concentration of 1 mol / L in a solvent of ethylene carbonate / ethyl methyl carbonate = 1/1 (mass ratio).

(2) Evaluation of Charging / Discharging Rate Characteristics With respect to the electricity storage device manufactured above, charging was started at room temperature at a constant current (0.2 C), and when the voltage reached 4.2 V, the constant voltage (4 .2V), charging was continued, and when the current value reached 0.01C, charging was completed (cut off), and the charging capacity at 0.2C was measured. Next, discharge was started at a constant current (0.2 C), and when the voltage reached 2.7 V, the discharge was completed (cut off), and the discharge capacity at 0.2 C was measured.

  Next, charging is started at a constant current (3C) for the same cell, and when the voltage reaches 4.2V, charging is continued at a constant voltage (4.2V). The charging capacity at 3C was measured with the time point of becoming the completion of charging (cut-off). Next, discharge was started at a constant current (3C), and when the voltage reached 2.7 V, the discharge was completed (cut off), and the discharge capacity at 3C was measured.

  Using the measured values above, calculate the charge rate (%) by calculating the ratio (percent%) of the charge capacity at 3C to the charge capacity at 0.2C at 3C versus the discharge capacity at 0.2C. The discharge rate (%) was calculated by calculating the discharge capacity ratio (percentage%). In Table 1, when both of the charge rate and the discharge rate are 80% or more, it is judged that the charge / discharge rate characteristics are good, and “◯”. When at least one of the charge rate and the discharge rate was less than 80%, the charge / discharge rate characteristics were judged to be poor and indicated as “x”. The results are also shown in Table 1.

In the measurement conditions, “1C” indicates a current value at which discharge is completed in one hour after constant current discharge of a cell having a certain electric capacity. For example, “0.1 C” is a current value at which discharge is completed over 10 hours, and 10 C is a current value at which discharge is completed over 0.1 hours.

4.4. Example 2, Comparative Examples 1-2
In Example 2 and Comparative Examples 1 and 2, in Example 1 above, the type, surface roughness and thickness of the stainless steel foil, the type and average particle size of the conductive additive particles, the type and thickness of the active material particles are respectively shown. Except that it was as described in 1, an electrode for an electricity storage device and an electricity storage device were produced in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are also shown in Table 1. The positive electrode power storage device electrode slurry used in Comparative Example 2 was prepared by adjusting the pH to 12.3 using an aqueous sodium hydroxide solution.

4.5. Examples 3-4
In Examples 3 to 4, in producing the electrode for a power storage device (negative electrode) in Example 1 above, the binder B was used instead of the binder A, and the type, surface roughness and thickness of the stainless steel foil, conductive auxiliary agent particles An electrode for an electricity storage device and an electricity storage device were prepared in the same manner as in Example 1 except that the type and average particle size of the particles, the type and thickness of the active material particles were as shown in Table 1, and the same as in Example 1. And evaluated. The results are also shown in Table 1.

In Table 1 above, “C / SiO” used as the active material particles of the negative electrode represents the graphite-coated silicon oxide prepared above. Moreover, the abbreviation of each material used as the conductive auxiliary agent particle of the above Table 1 represents the following brand names, respectively.
<Conductive aid particles>
DB 50% (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Denka Black 50% Pressed Product”, carbon black, average particle size 0.036 μm)
-DB 75% (made by Denki Kagaku Kogyo Co., Ltd., trade name “Denka Black 50% Pressed Product”
Carbon black, average particle size 0.036μm)
DB FX-35 (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Denka Black FX-35”, carbon black, average particle size 0.026 μm)
DB HS-100 (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Denka Black HS-100”, carbon black, average particle size 0.048 μm)
CB VULCAN 9A32 (manufactured by Cabot Japan Co., Ltd., trade name “Cabot VULCAN 9A32”, carbon black, average particle size 0.019 μm)
MB # 3230B (Mitsubishi Chemical Corporation, trade name “Mitsubishi Carbon Black # 3230B”, carbon black, average particle size 0.023 μm)

4.7. Evaluation Results As is apparent from Table 1 above, the electricity storage device produced using the electricity storage device electrode obtained by the production method of the present invention shown in Examples 1 to 4 has good charge / discharge rate characteristics. It has been found. On the other hand, as is clear from Comparative Examples 1 and 2, the electricity storage device produced using the electricity storage device electrode obtained by the production method that was not the production method of the present invention had poor charge / discharge rate characteristics.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 10, 10a, 10b ... Stainless steel collector, 20, 20a, 20b ... Active material layer, 30a, 30b ... Conductive auxiliary agent particle, 40a, 40b ... Active material particle, 100, 200 ... Electrode for electrical storage device

Claims (11)

A method for producing an electrode for an electricity storage device comprising a stainless steel current collector and an active material layer formed on a surface of the stainless steel current collector,
A first step of preparing a slurry for an electricity storage device electrode containing conductive auxiliary particles and active material particles and having a pH of 9 to 12;
A second step of forming the active material layer by applying and drying the slurry for the electricity storage device electrode on the surface of the stainless steel current collector;
The manufacturing method of the electrode for electrical storage devices containing this.   The manufacturing method of the electrode for electrical storage devices of Claim 1 whose said active material particle is a lithium containing nickel (composite) oxide particle.   The manufacturing method of the electrode for electrical storage devices of Claim 1 or Claim 2 whose said electrode for electrical storage devices is a positive electrode.   In the second step, when the thickness of the stainless steel current collector is At (μm) and the thickness of the active material layer is Bt (μm), the relationship of 1 <Bt / At <50 is satisfied. The manufacturing method of the electrode for electrical storage devices as described in any one of Claims 1 thru | or 3 which apply | coats the said slurry for electrical storage device electrodes on the surface of a stainless steel electrical power collector.   The manufacturing method of the electrode for electrical storage devices of Claim 4 whose thickness At of the said stainless steel electrical power collector is 1-50 micrometers.   The manufacturing method of the electrode for electrical storage devices of Claim 4 or Claim 5 whose thickness Bt of the said active material layer is 20-200 micrometers.   The relationship of D <Ra is satisfied when the surface roughness of the stainless steel current collector is Ra (μm) and the average particle diameter of the conductive auxiliary agent particles is D (μm). The manufacturing method of the electrode for electrical storage devices as described in any one.   The manufacturing method of the electrode for electrical storage devices of Claim 7 whose surface roughness Ra of the said stainless steel electrical power collector is 0.03-1 micrometer.   The manufacturing method of the electrode for electrical storage devices of Claim 7 or Claim 8 whose average particle diameter D of the said conductive support agent particle | grain is 0.01-0.1 micrometer.   The electrode for electrical storage devices manufactured by the manufacturing method of the electrode for electrical storage devices as described in any one of Claims 1 thru | or 9.   An electricity storage device comprising the electrode for an electricity storage device according to claim 10.