JP2016162681A - Electrode precursor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode whose shape change is sufficiently suppressed even after charge/discharge cycle is repeated.SOLUTION: Disclosed is an electrode precursor containing an electrode active material. This electrode precursor further includes a polymer and layered double hydroxy compound.SELECTED DRAWING: None

Description

The present invention relates to an electrode precursor. More specifically, the present invention relates to an electrode precursor that can be suitably used as a material for an electrode constituting a battery.

In recent years, the importance of batteries has increased rapidly in many industries, from small portable devices to large-scale applications such as automobiles. New battery systems that have advantages mainly in terms of capacity, energy density, and secondary battery use. Have been developed and improved.
Among these various batteries, a zinc negative electrode using a zinc species as a negative electrode active material has been studied for a long time with the spread of batteries. Examples of the battery using the zinc negative electrode include a primary battery, a secondary battery (storage battery), an air battery, and the like. For example, an air / zinc battery using oxygen in the air as the positive electrode active material, and a nickel-containing compound as the positive electrode active material. Research and development of nickel / zinc batteries used, manganese / zinc batteries and zinc ion batteries using manganese-containing compounds as the positive electrode active material, and silver / zinc batteries using silver oxide as the positive electrode active material, especially air / zinc primary Batteries, manganese / zinc primary batteries, and silver / zinc primary batteries have been put into practical use and are widely used in the world.
Thus, although zinc is widely distributed as a primary battery, secondary batteries are not used. The cause is that a short circuit is likely to occur due to dendrites, and a shape change occurs in which the form of the electrode changes depending on the charge / discharge cycle. Even if it constituted as a secondary battery by these effects | actions, the lifetime was short and the performance was inferior to other battery systems.

Many technologies have been developed for such problems, and as one of them, a technique for suppressing the growth of zinc in a dendrite shape using a semipermeable membrane or the like has been studied. For example, a cathode group in which an alkaline earth metal hydroxide layer is formed on the counter electrode surface of a zinc cathode, and the outer side of the hydroxide layer is covered with a semipermeable membrane that does not allow zincate ions to pass through, and an electrolyte absorber. A zinc-alkali secondary battery is disclosed in which a zinc-alkaline secondary battery is constituted by the anode and the anode, and the amount of the electrolyte in the entire battery is regulated within a range of about 2.3 to 4.0 ml per 1 AH discharge capacity of the cathode. (For example, refer to Patent Document 1). Further, a zinc alkaline secondary battery in which a porous layer of magnesium oxide is adhered to the surface of a negative electrode using zinc as an active material is disclosed (for example, see Patent Document 2). Furthermore, a positive electrode, a negative electrode including at least one of zinc and a zinc compound as a negative electrode active material, a coating including an ion exchange resin formed on the negative electrode or the negative electrode active material, and an electrolyte including an alkaline aqueous solution as an electrolyte. And at least one selected from the group consisting of the negative electrode, the coating, and the electrolyte is a metal that is nobler than the standard electrode potential of zinc and has a melting point lower than the melting point of zinc, an oxide containing the metal, An alkaline secondary battery including a salt containing a metal and at least one selected from the group consisting of ions containing the metal is disclosed (for example, see Patent Document 3). Also disclosed is a zinc negative electrode active material for a zinc-alkali secondary battery coated with a hydroxide that does not exhibit substantial solubility in an alkaline aqueous solution and does not undergo oxidation / reduction reactions in the potential range of the charge / discharge reaction of the battery. (For example, refer to Patent Document 4).

By the way, the technique which applies an ion conductive matrix, a solid electrolyte, etc. to the constituent material of a battery electrode, an electrolyte, or a separator is disclosed (for example, refer patent documents 5-11).
Further, it is disclosed that zinc-aluminum-hydrotalcite is used as a negative electrode material for a nickel / zinc secondary battery (see, for example, Non-Patent Document 1).

JP 52-88739 A JP-A-57-163963 JP 2013-54877 A JP-A-5-144431 Special Table 2002-505506 JP 2000-67920 A JP 2005-228541 A Japanese Patent No. 4781263 Special table 2010-520095 gazette JP 2000-123633 A JP 2005-235664 A

“Journal of Power Sources”, 2013, Vol. 224, p. 80-85

As described above, various techniques for solving the problem in the case of using a zinc negative electrode have been proposed, but it cannot be said that the conventional invention sufficiently suppresses the shape change of the zinc negative electrode. Electrode shape change is a problem that occurs not only with zinc negative electrodes but also with electrodes that use lithium or cadmium as an active material. In these electrodes, electrode shape change is sufficiently suppressed even after repeated charge and discharge cycles. There is room for further improvement in battery life.

This invention is made | formed in view of the said present condition, and it aims at providing the electrode by which shape change was fully suppressed after repeating a charging / discharging cycle.

The inventor of the present invention has studied various methods for suppressing the shape change of the electrode, and has paid attention to an electrode precursor as a material for the electrode. And, when an electrode is formed using an electrode precursor containing a polymer and a layered double water compound in addition to the active material, the shape change of the resulting electrode is effectively suppressed, and the battery life is extended. As a result, the present inventors have arrived at the present invention.

That is, this invention is an electrode precursor containing an electrode active material, Comprising: The said electrode precursor is an electrode precursor characterized by including a polymer and a layered double water compound further.
The present invention is described in detail below.
A combination of two or more preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.

<Electrode precursor>
The electrode precursor of the present invention is characterized by further containing a polymer and a layered double water compound in addition to the active material. The layered double water compound has a layered structure in which metal hydroxide layers are stacked, and has gaps (pores) between the layers. In a battery using zinc species, lithium species or cadmium species as an active material, the metal species of these active materials are repeatedly dissolved (ionized) and precipitated (compounded) in the process of charging and discharging. The ionized metal species can move freely, and the ionized metal species move from the original location and precipitate, thereby causing an electrode shape change. On the other hand, by adding a layered double water compound to the electrode precursor, the metal species are filled in gaps (pores) between the layers of the layered double water compound, thereby restricting movement when the metal species are ionized. As a result, the electrode shape change is suppressed. In addition, even when charging and discharging are repeated, separation of the metal species and the binder component contained in the active material layer is suppressed, and a problem that the binder component is unevenly distributed in the active material layer to increase internal resistance can be suppressed. .
The electrode precursor of the present invention may contain one kind of active material, polymer and layered double water compound, respectively, or may contain two or more kinds.
The electrode precursor of the present invention may contain other components as long as it contains an active material, a polymer, and a layered double water compound.

As the layered double water compound contained in the electrode precursor of the present invention, the following formula (1);
[M ¹ _1-x M ² _x (OH) ₂ ] (A ⁿ⁻ ) _{x / n} · mH ₂ O (1)
^{(M 1} are, Mg, Fe, Zn, Ca , Li, Ni, Co, .M 2 represent either a Cu are, ^{.A n-is} representing Al, Fe, one of Mn, 1 to 3-valent M is a number of 0 or more, n is a number of 1 to 3, and x is a number of 0.20 to 0.40). Further, a compound dehydrated by firing at 150 ° C. to 900 ° C., a compound obtained by decomposing an anion in the interlayer, and a compound in which the anion in the interlayer is exchanged with a hydroxide ion or the like can be suitably used. . Further, it is possible to use _{Mg 6 Al 2 (OH) 16} CO 3 · mH 2 O , etc. is also suitably a natural mineral.
The layered double water compound may be coordinated with a compound having a functional group such as a hydroxyl group, an amino group, a carboxyl group, or a silanol group.
The monovalent to trivalent anion represented by ^{A n-} in the above formula _{^{(1), CO 3 2-,}} OH -, PO 4 3-, Fe (CN) 6 3- , and the like.

The content of the layered double water compound in the electrode precursor of the present invention is 0.1 to 30% by weight with respect to 100% by weight in total of the active material, layered double water compound and polymer (solid content) included in the electrode precursor. % Is preferred. By including in such a ratio, the effect of suppressing the electrode shape change can be more fully exhibited. More preferably, it is 0.5-10 mass% with respect to a total of 100 mass% of a layered double water compound and a polymer (solid content), More preferably, it is 1-5 mass%.
Note that when the electrode formed using the electrode precursor of the present invention has a distribution in which the active material concentration in the active material layer, which will be described later, decreases as the distance from the current collector decreases, a layered composite is formed. An electrode precursor having a higher content of water compound than the above can also be used as a material for forming the active material layer at a position away from the current collector. The content of the layered double water compound in such an electrode precursor is 30 to 90% by weight with respect to a total of 100% by weight of the active material, the layered double water compound and the polymer (solid content) included in the electrode precursor. Preferably there is. When the content of the layered double water compound is more than 90% by mass (relatively the active material ratio is reduced), the function as the active material layer is reduced, and only the function as a separator is obtained. When considered as the material of the layer, the content of the layered double water compound is preferably 90% by mass or less.
Therefore, an active material layer in which the active material concentration in the active material layer has no distribution, or a layered state in the electrode precursor that forms an active material layer at a position close to the current collector when the active material concentration has a distribution. The content of the double water compound is preferably in the range of 0.1 to 30% by mass and the like, and an electrode precursor that forms an active material layer at a position far from the current collector when the active material concentration has a distribution. The content of the layered double water compound is preferably 30 to 70% by mass.

Examples of the polymer contained in the electrode precursor of the present invention include hydrocarbon group-containing polymers such as polyethylene and polypropylene; aromatic group-containing polymers represented by polystyrene; ether group-containing polymers represented by alkylene glycol; polyvinyl alcohol, Hydroxyl group-containing polymers typified by poly (α-hydroxymethyl acrylate); amide bond-containing polymers typified by polyamide, nylon, polyacrylamide, polyvinylpyrrolidone, N-substituted polyacrylamide, etc .; typified by polymaleimide, etc. Imide bond-containing polymers; carboxyl group-containing polymers represented by poly (meth) acrylic acid, polymaleic acid, polyitaconic acid, polymethyleneglutaric acid, etc .; poly (meth) acrylate, polymaleate, polyitaconate, poly Carboxylate-containing polymers such as methylene glutarate; halogen-containing polymers such as polyvinyl chloride, polyvinylidene fluoride, and polytetrafluoroethylene; polymers bonded by opening of epoxy groups such as epoxy resins; sulfones AR ¹ R ² R ³ B (A represents N or P. B represents an anion such as a halogen anion or OH ^−, and R ¹ , R ² , and R ³ are the same or different. And represents an alkyl group having 1 to 7 carbon atoms, a hydroxyalkyl group, an alkyl carboxyl group, or an aromatic ring group, and R ¹ , R ² , and R ³ may combine to form a ring structure. Quaternary ammonium salt and quaternary phosphonium salt-containing polymers represented by polymers with attached groups; ions used in cation / anion exchange membranes, etc. Exchangeable polymer; natural rubber; artificial rubber represented by styrene butadiene rubber (SBR), etc .; cellulose, cellulose acetate, hydroxyalkyl cellulose (for example, hydroxyethyl cellulose), carboxymethyl cellulose, chitin, chitosan, alginic acid (salt), etc. Saccharides represented; Amino group-containing polymers represented by polyethyleneimine; Carbamate group site-containing polymers; Carbamide group site-containing polymers; Epoxy group site-containing polymers; Heterocycles and / or ionized heterocyclic site-containing polymers; Polymers Alloy; heteroatom-containing polymer; low molecular weight surfactant and the like. These polymers serve as binders for the electrode precursor.

Among the above polymers, the polymer contained in the electrode precursor of the present invention is preferably a polymer having at least one selected from the group consisting of halogen atoms, carboxyl groups, hydroxyl groups and ether groups. Polymers having a carboxylate instead of a carboxyl group are also preferred. More preferred are fluorine-containing polymers such as polyvinylidene fluoride and polytetrafluoroethylene. When a fluorine-containing polymer is used, when the electrode precursor is prepared by kneading the active material, the layered double water compound and the polymer, the fiberization of the polymer is promoted, and as a result, the active material produced using the electrode precursor By inhibiting the movement of the zinc species in the layer, the effect of suppressing the electrode shape change is more fully exhibited.

Polymer is radical polymerization, radical (alternate) copolymerization, anion polymerization, anion (alternate) copolymerization, cationic polymerization, cationic (alternate) copolymerization, graft polymerization, graft (alternate) copolymerization from monomers corresponding to the structural unit. , Living polymerization, living (alternate) copolymerization, dispersion polymerization, emulsion polymerization, suspension polymerization, ring-opening polymerization, cyclization polymerization, polymerization by light, ultraviolet ray or electron beam irradiation, metathesis polymerization, electrolytic polymerization, etc. . When these polymers have a functional group, they may be present in the main chain and / or side chain, and may exist as a binding site with a crosslinking agent. These polymers may be used alone or in combination of two or more.
The polymer is an ester bond, an amide bond, an ionic bond, a van der Waals bond, an agostic interaction, a hydrogen bond, an acetal bond, a ketal bond, an ether bond, by the layered double water compound or other organic crosslinking agent compound, Crosslinking via peroxide bond, carbon-carbon bond, carbon-nitrogen bond, carbon-oxygen bond, carbon-sulfur bond, carbamate bond, thiocarbamate bond, carbamide bond, thiocarbamide bond, oxazoline moiety-containing bond, triazine bond, etc. May be.

The polymer preferably has a weight average molecular weight of 200 to 7000000. Thereby, the ion conductivity, flexibility, etc. of an electrode precursor can be adjusted. The weight average molecular weight of the polymer is more preferably 400 to 6500000, and still more preferably 500 to 5000000.
The weight average molecular weight can be measured by gel permeation chromatography (GPC).

The ratio of the polymer in the electrode precursor is preferably 0.01 to 10% by mass with respect to 100% by mass in total of the active material, the layered double water compound and the polymer (solid content) included in the electrode precursor. . More preferably, it is 0.1-6 mass%, More preferably, it is 1-5 mass%.

The electrode active material included in the electrode precursor of the present invention preferably contains zinc species, lithium species or cadmium species. The electrode precursor of the present invention can effectively suppress electrode shape change that occurs when these metal species are included as an active material. Here, the metal species means a metal simple substance or a metal compound.
Examples of the lithium species and cadmium species include metal lithium alone and metal cadmium alone, and examples of zinc species include the following.
The electrode active material included in the electrode precursor of the present invention preferably contains a zinc species.

As the zinc species contained in the electrode precursor of the present invention, the zinc-containing compound may be any material that can be used as an active material in addition to metal zinc alone. For example, zinc oxide (specified in JIS K1410 (2006)). 1 type / 2 types / 3 types), zinc hydroxide, zinc sulfide, tetrahydroxyzinc alkali metal salt, tetrahydroxyzinc alkaline earth metal salt, zinc halogen compound, zinc carboxylate compound, zinc alloy, zinc solid solution, Zinc borate / zinc phosphate / zinc hydrogen phosphate / zinc silicate / zinc aluminate / carbonate compounds / hydrogen carbonate compounds / nitric acid compounds / sulfuric acid compounds Examples include zinc (alloy) compounds, organic zinc compounds, zinc compound salts, and the like having at least one element selected from the group consisting of elements.
Among these, zinc oxide (1 type / 2 types / 3 specified in JIS K1410 (2006)), zinc hydroxide, tetrahydroxy zinc alkali metal salt, tetrahydroxy zinc alkaline earth metal salt, zinc halogen compound, Zinc carboxylate compound, zinc alloy, zinc solid solution, zinc borate, zinc phosphate, zinc silicate, zinc aluminate, zinc carbonate, selected from the group consisting of elements belonging to groups 1 to 17 of the periodic table More preferred are zinc (alloy) compounds having at least one element. The zinc alloy may be a zinc alloy used in an (alkali) dry battery or an air battery. The zinc-containing compound can be used alone or in combination of two or more.

The zinc species used as the active material preferably has an average particle size of 0.1 to 200 μm. By using a material having such an average particle size, it is possible to obtain a large surface area in which the electrolytic solution can easily soak into the entire electrode and cause an electrochemical reaction. The average particle size of the zinc species is more preferably 0.2 to 100 μm, and still more preferably 0.5 to 10 μm.
The average particle size of the zinc species can be measured using a particle size distribution measuring device.

The ratio of the metal seed | species which the electrode precursor of this invention contains as an active material is 50-99.9 mass with respect to a total of 100 mass% of the active material, layered double water compound, and polymer (solid content) which an electrode precursor contains. % Is preferred. When the proportion of the active material is in such a range, the electrode formed using the electrode precursor becomes more sufficient in terms of battery capacity. More preferably, it is 55 to 99.5% by mass, and more preferably 60 to 99% by mass with respect to 100% by mass in total of the active material, layered double water compound and polymer (solid content) contained in the electrode precursor. It is.

The electrode precursor of the present invention is a simple element of element or a constituent element of these elements in order to suppress water decomposition side reaction that may occur when a water-containing electrolyte is used in a storage battery prepared using the electrode precursor. May be included. Specific elements include Al, B, Ba, Bi, Br, C, Ca, Cd, Ce, Cl, Cu, Eu, F, Ga, Hg, In, La, Mg, Mn, N, Nb, Nd, Ni, P, Pb, S, Sb, Sc, Si, Sm, Sn, Sr, Ti, Tl, Y, Zr, etc. are mentioned.

The electrode precursor of the present invention preferably further contains a conductive additive. By including a conductive additive, the conductivity of the active material layer formed using the electrode precursor is increased, and the capacity of the battery can be further increased by effectively using the active material contained in the active material layer. .
Examples of the conductive assistant include conductive carbon, conductive ceramics, zinc / zinc powder / zinc alloy / (alkali) (storage) zinc used in dry batteries and air batteries (hereinafter also referred to as metal zinc). One kind or two or more kinds of metals such as copper, brass, nickel, silver, bismuth, indium, lead, and tin can be used.

Examples of the conductive carbon include graphite such as natural graphite and artificial graphite, glassy carbon, amorphous carbon, graphitizable carbon, non-graphitizable carbon, carbon nanofoam, activated carbon, graphene, nanographene, graphene nanoribbon, fullerene, carbon black, Graphitized carbon black, ketjen black, vapor grown carbon fiber, pitch-based carbon fiber, mesocarbon microbead, carbon coated with metal, carbon coated metal, fibrous carbon, boron-containing carbon, nitrogen-containing carbon, multilayer / Single-walled carbon nanotubes, carbon nanohorns, Vulcan, acetylene black, carbon treated by introducing oxygen-containing functional groups, SiC-coated carbon, expressed by dispersion / emulsion / suspension / microsuspension polymerization, etc. Treated carbon, microcapsules carbon.

Examples of the conductive ceramic include a compound containing at least one selected from Bi, Co, Nb, and Y fired with zinc oxide.

Among the above conductive aids, graphite such as natural graphite and artificial graphite, graphitizable carbon, non-graphitizable carbon, graphene, carbon black, graphitized carbon black, ketjen black, vapor-grown carbon fiber, pitch-based carbon fiber , Mesocarbon microbeads, fibrous carbon, multi-walled / single-walled carbon nanotubes, Vulcan, acetylene black, carbon treated with hydrophilicity by introducing oxygen-containing functional groups, metallic zinc, copper, brass, nickel, silver, bismuth, indium -Metals such as lead and tin are preferred. In addition, the metal zinc may be used for an actual battery such as an alkaline (storage) battery or an air battery, or may have a surface treated with other elements or carbon, or may be alloyed. May be. It may be a solid solution. The said conductive support agent can be used by 1 type, or 2 or more types.

The metallic zinc can also act as an active material. In other words, in the process of using the battery, metallic zinc, which is a conductive additive, performs a redox reaction and functions as an active material. Similarly, in the process of using the battery, metallic zinc produced from a zinc-containing compound as an active material also functions as a conductive additive. Metal zinc and a zinc-containing compound added as a mixture in the preparation stage of an electrode such as a negative electrode substantially function as an active material and a conductive aid in the process of using the battery.

In order to suppress the water decomposition side reaction when the water-containing electrolyte is used, the conductive auxiliary agent contains a single element of the same element as the specific element described above or a compound containing these elements as constituent elements. It may be. When conductive carbon is used as one of the conductive assistants, specific elements include Al, B, Ba, Bi, C, Ca, Cd, Ce, Cu, F, Ga, In, La, and Mg. Mn, N, Nb, Nd, Ni, P, Pb, S, Sb, Sc, Si, Sn, Ti, Tl, Y, Zr are preferable.

It is preferable that the content rate in the electrode precursor of the said conductive support agent is 0.0001-100 mass% with respect to 100 mass% of active materials in an electrode precursor. When the content ratio of the conductive auxiliary is in such a range, better battery performance is exhibited when an electrode including an active material layer is used for a battery. More preferably, it is 0.0005-60 mass%, More preferably, it is 0.001-40 mass%.
In addition, when using metallic zinc as a component of an electrode precursor, metallic zinc is considered not as an active material but as a conductive additive. Further, in the electrode precursor of the present invention using zinc species as an active material, metallic zinc produced in the process of battery use from zinc oxide or zinc hydroxide, which is a zinc-containing compound, is used as a conductive aid in the system. Although the function is also fulfilled, since it is not zero-valent metal zinc at the time of preparing the electrode precursor or the electrode (zinc negative electrode), it is not considered as a conductive additive here, but is calculated as an active material. That is, a preferable content ratio of the active material and the conductive auxiliary agent is calculated by considering the zinc-containing compound at the time of preparing the electrode precursor and the electrode (zinc negative electrode) as an active material and zinc metal as a conductive auxiliary agent.

The electrode precursor of the present invention may contain a solvent. Examples of the solvent contained in the electrode precursor include water, ethanol, acetone, isopropyl alcohol, butanol, butyl acetate, N-methylpyrrolidone, and the like, and one or more of these can be used.
It is preferable that content of the solvent of an electrode precursor is 0.001-2 mass% with respect to 100 mass% of the whole electrode precursor. More preferably, it is 0.01-1 mass%.

The electrode precursor of the present invention may contain one or more other components other than zinc species, polymers, layered double water compounds, and solvents.
Other components are not particularly limited, and examples thereof include alumina, silica, and conductive ceramics. Other components can function to assist ionic conductivity.

<Electrode>
The present invention is also an electrode including a current collector and an active material layer, and the active material layer is also an electrode formed using the above-described electrode precursor of the present invention.
As described above, the electrode formed using the electrode precursor of the present invention has a shape change suppressed, and the use of this electrode can extend the life of the battery.

The active material layer included in the electrode of the present invention preferably has a thickness of 0.5 mm or more. In the electrode of the present invention, the shape change is effectively suppressed, and such an effect is remarkably exhibited when an electrode having a thick active material layer in which the shape change is likely to occur is formed. The thickness of the active material layer is more preferably 0.7 mm or more. More preferably, it is 1.0 mm or more. In addition, if the thickness of the active material layer is too thick, the active material layer may fall off from the current collector. Therefore, the thickness of the active material layer is preferably 50 mm or less.
The thickness of the active material layer here means the thickness of the entire active material layer. In the case of an active material layer having a structure in which a plurality of active material layers are stacked, the thickness of the plurality of stacked active material layers is the same. It means thickness.
The thickness of the active material layer can be measured with a micrometer.

The structure of the electrode of the electrode of the present invention is not particularly limited as long as the active material layer is formed using the electrode precursor of the present invention, but it is opposite to the current collector from the side in contact with the current collector. It is preferable that the layered double water compound and the active material are distributed toward the surface side of the active material layer so that the weight ratio of the active material to the layered double water compound contained in the active material layer decreases.
Thus, in the electrode active material layer, the proportion of the active material increases as it is closer to the current collector, and the proportion of the layered double water compound increases as it approaches the surface of the active material layer farther from the current collector. If so, the proportion of the active material in the active material layer that is utilized for charging / discharging increases, the battery capacity increases, and the effect of suppressing shape change is more fully exhibited. Furthermore, even after repeated charge and discharge, separation of the metal species as the active material and the polymer as the binder component can be suppressed, and an increase in internal resistance due to the uneven distribution of the binder component can be more sufficiently suppressed.
Here, the active material layer is distributed so that the weight ratio of the active material to the layered double water compound contained in the active material layer decreases from the side in contact with the current collector to the surface side of the active material layer opposite to the current collector. In the embodiment, the weight ratio of the active material to the layered double water compound in the active material layer is continuously increased from the side in contact with the current collector to the surface side of the active material layer opposite to the current collector. The active material layer is composed of a plurality of layers in addition to the form (first form) distributed so as to decrease from the side in contact with the current collector toward the side opposite to the current collector. In addition, a form (second form) in which a plurality of layers are laminated so that the weight ratio of the active material to the layered double water compound is decreased, and the first form and the second form are included. It may be a combination.
In the case of the second form, there is no layer in which the weight ratio of the active material to the layered double water compound is larger in the layer opposite to the current collector among the two adjacent layers in the active material layer As long as the layer constituting the active material layer includes a layer in which the weight ratio of the active material to the two adjacent layered double water compounds is the same. The same applies to the combination of the first form and the second form.

In the case of the second embodiment, it is possible to finely adjust the distribution of the weight ratio of the active material to the layered double water compound as the number of active material layers to be laminated increases, but the manufacturing process of the active material increases. It becomes complicated. Considering both the effect of having a distribution of the weight ratio of the active material to the layered double water compound and the ease of production of the active material layer, the number of active material layers to be stacked should be 2 to 20 layers. Is preferred. More preferably, it is 3 to 10 layers.

In the case of the second embodiment, the ratio of the thickness of the active material layer to be stacked is not particularly limited, but the ratio of the thickness of the thinnest layer to the thickness of the thickest layer among the stacked layers is 1/100 to 1. (1/1) is preferable. If there is a thin layer that deviates from this ratio, the effect of having the layer will not be exhibited, and if there is a thick layer that deviates from this ratio, the influence of the layer on the entire active material layer becomes too great, and the active material layer The effect of providing a weight ratio distribution of the active material to the layered double water compound cannot be sufficiently exhibited. The ratio of the thickness of the thinnest layer to the thickness of the thickest layer is more preferably 1/50 to 4/5, and still more preferably 1/20 to 3/4.
The thickness of the active material layer can be measured with a micrometer.

In the active material layer, the concentration of the active material in the layer having the lowest weight ratio is 90 to 10% with respect to the concentration (mass%) of the active material in the layer having the highest weight ratio of the active material to the layered double water compound. It is preferable that If the active material concentration in the active material layer is different so that the concentration of the active material satisfies such a ratio, the effective utilization rate of the active material in the active material layer is increased and the capacity of the electrode is further increased. be able to. The concentration of the active material in the layer having the lowest weight ratio to the concentration of the active material in the layer having the highest weight ratio of the active material to the layered double water compound is more preferably 85 to 20%, and still more preferably. Is 70-30%.
When the layer having the highest or lowest weight ratio of the active material to the layered double water compound is a layer having an active material concentration distribution in one active material layer (in the case of the first embodiment). , “The concentration of the active material in the layer having the highest weight ratio of the active material to the layered double water compound” is the average of the active material concentration in the layer for 10% of the total thickness of the active material layer from the current collector side, “The concentration of the active material in the layer having the lowest weight ratio of the active material to the layered double water compound” is a layer corresponding to 10% of the total thickness of the active material layer from the surface side of the active material layer opposite to the current collector The average of the active material concentration in it.

Current collectors constituting the electrode of the present invention include (electrolytic) copper foil, copper mesh (expanded metal), foamed copper, punched copper, copper alloys such as brass, brass foil, brass mesh (expanded metal), foamed brass , Punching brass, nickel foil, corrosion resistant nickel, nickel mesh (expanded metal), punching nickel, metallic zinc, corrosion resistant metallic zinc, zinc foil, zinc mesh (expanded metal), (punched) steel sheet, non-woven fabric imparted with conductivity; Ni・ Zinc, Sn, Pb, Hg, Bi, In, Tl, brass, etc. (electrolytic) copper foil, copper mesh (expanded metal), copper alloy such as foamed copper, punched copper, brass, brass foil, brass mesh (Expanded metal), foamed brass, punched brass, nickel foil, corrosion resistant nickel, nickel mesh Pand Metal), Punched Nickel, Metallic Zinc, Corrosion Resistant Metal Zinc, Zinc Foil, Zinc Mesh (Expanded Metal), (Punched) Steel Sheet, Nonwoven Fabric; Ni, Zn, Sn, Pb, Hg, Bi, In, Tl, Brass Plated (electrolytic) copper foil, copper mesh (expanded metal), foamed copper, punched copper, brass and other copper alloys, brass foil, brass mesh (expanded metal), foamed brass, punched brass, nickel foil, corrosion-resistant nickel, Nickel mesh (expanded metal), punched nickel, metallic zinc, corrosion-resistant metal zinc, zinc foil, zinc mesh (expanded metal), (punched) steel sheet, non-woven fabric; silver; current collectors for alkaline (storage) batteries and air zinc batteries Examples include materials used as containers.

The electrode of the present invention is a production method comprising a step of forming an active material layer containing an active material by coating, pressing, adhering, piezoelectric, rolling, stretching, melting, etc. the electrode precursor of the present invention on a current collector Can be manufactured. When the electrode of the present invention has a structure in which two or more active material layers are laminated, the electrode can be produced by performing the step of forming the active material layer twice or more.

<Battery>
As described above, in the electrode of the present invention, the shape change is effectively suppressed, and the use of this electrode can extend the life of the battery. A battery constructed using such an electrode of the present invention is also one aspect of the present invention.

When the battery of the present invention is a battery including the electrode of the present invention as a zinc negative electrode having a zinc species as an active material, a positive electrode active material that is usually used as a positive electrode active material of a primary battery or a secondary battery is used. Although not particularly limited, for example, oxygen (when oxygen is a positive electrode active material, the positive electrode is a perovskite type compound capable of reducing oxygen or oxidizing water, a cobalt-containing compound, an iron-containing compound, a copper-containing compound) And nickel compounds such as nickel oxyhydroxide, nickel hydroxide, and cobalt-containing nickel hydroxide, and silver oxide. Among these, it is preferable that a positive electrode active material is oxygen.
As described above, since the electrode of the present invention can effectively use the active material in the active material layer even when the thickness of the active material is increased, the thickness of the negative electrode active material is increased in order to increase the capacity. It is suitable to be used as a negative electrode of a zinc-air battery that is required to do. Therefore, it is one of the preferred embodiments of the present invention that the battery of the present invention is an air zinc battery.
Moreover, as a form of the battery using the electrode of the present invention as a negative electrode, a primary battery, a secondary battery capable of charging / discharging, use of mechanical charge (mechanical replacement of a zinc negative electrode), the negative electrode of the present invention and the above-mentioned are described. Any form such as utilization of a third electrode different from the positive electrode composed of such a positive electrode active material may be used.

As the electrolytic solution used in the battery of the present invention, those commonly used as an electrolytic solution for a storage battery can be used, and are not particularly limited. For example, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, dimethoxy Methane, diethoxymethane, dimethoxyethane, tetrahydrofuran, methyltetrahydrofuran, diethoxyethane, dimethyl sulfoxide, sulfolane, acetonitrile, benzonitrile, ionic liquid, fluorine-containing carbonates, fluorine-containing ethers, polyethylene glycols, fluorine-containing polyethylene glycol And the like. The organic solvent electrolyte can be used alone or in combination of two or more. Examples of the aqueous electrolyte include potassium hydroxide aqueous solution, sodium hydroxide aqueous solution, lithium hydroxide aqueous solution, zinc sulfate aqueous solution, zinc nitrate aqueous solution, zinc phosphate aqueous solution and zinc acetate aqueous solution. Among these, alkaline electrolytes such as an aqueous potassium hydroxide solution, an aqueous sodium hydroxide solution, and an aqueous lithium hydroxide solution are preferable. The aqueous electrolyte solution can be used alone or in combination of two or more. The aqueous electrolyte solution may contain the organic solvent electrolyte solution.

As the battery of the present invention, a separator can also be used. The separator is a member that separates the positive electrode and the negative electrode and holds the electrolyte solution to ensure ionic conductivity between the positive electrode and the negative electrode. There is no particular limitation as a separator, but non-woven fabric, filter paper, polymers containing hydrocarbon moieties such as polyethylene and polypropylene, polymers containing polytetrafluoroethylene moieties, polymers containing polyvinylidene fluoride, cellulose, fibrillated cellulose, viscose rayon, cellulose acetate , Hydroxyalkyl cellulose, carboxymethyl cellulose, polyvinyl alcohol-containing polymer, cellophane, polystyrene-containing aromatic ring site-containing polymer, polyacrylonitrile site-containing polymer, polyacrylamide site-containing polymer, polyhalogenated vinyl site-containing polymer, polyamide site-containing polymer, polyimide Site-containing polymer, ester site-containing polymer such as nylon, poly (meth) acrylic acid site-containing polymer, poly (meth) a Rylate site-containing polymer, hydroxyl group-containing polymer such as polyisoprenol and poly (meth) allyl alcohol, carbonate group-containing polymer such as polycarbonate, ester group-containing polymer such as polyester, carbamate and carbamide group site-containing polymer such as polyurethane, Agar, gel compound, organic-inorganic hybrid (composite) compound, ion exchange membrane polymer, cyclized polymer, sulfonate-containing polymer, quaternary ammonium salt-containing polymer, quaternary phosphonium salt polymer, cyclic hydrocarbon group-containing polymer And inorganic substances such as ether group-containing polymers and ceramics. One of these may be sufficient as a separator, and 2 or more types may be sufficient as it.

Since the electrode precursor of the present invention has the above-described configuration and can form an electrode in which shape change is suppressed, a zinc negative electrode having a zinc species as an active material, particularly, a thick active material layer is formed. It can use suitably for the material which forms the zinc negative electrode of a zinc air battery.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by weight” and “%” means “mass%”.

Examples 1-5, Comparative Example 1
A 60% concentration polytetrafluoroethylene aqueous dispersion (Polyflon D-210C, manufactured by Daikin), hydrotalcite, and zinc oxide (average particle size 1 μm) were kneaded at a mass ratio shown in the following table to obtain an electrode precursor. A to F were prepared and pressed onto a tinned punched steel sheet by rolling to obtain a zinc electrode having a layer having a thickness of 2 mm. A 0.3 mm thick membrane prepared by kneading tetrafluoroethylene and hydrotalcite at a solid content weight ratio of 1: 1 as an anion conductive membrane is disposed on the surface of the zinc electrode. Was made. The integrated zinc electrode is disposed on the working electrode, a nickel electrode is used as the counter electrode, a mercury electrode is used as the reference electrode, and an 8M-concentrated KOH aqueous solution saturated with zinc oxide is used as an electrolyte to form a three-electrode battery cell. .
The charge / discharge reaction was measured using a charge / discharge current of 30 mA / cm ² and 50% of the theoretical capacity calculated from the weight of zinc oxide mounted on the zinc negative electrode. As a shape change evaluation after 200 cycles, the structure in which the thickness of the electrode central portion with respect to the active material thickness of the electrode outer peripheral portion was 30% or less was “◯”, and the active material moved within the electrode surface by the shape change. A film thickness ratio of 30% or more was evaluated as “x”. The results are shown in Table 1.
In Example 5, the proportion of hydrotalcite is large with respect to zinc oxide which is an active material, which tends to inhibit the formation of zinc during charging and to form electrically insulated zinc from the current collector during discharging. However, when the distribution of the composition of the active material layer is given, it can be used as a material for forming the active material layer at a position away from the current collector. is there.

Example 6
The electrode precursor A of Table 1 was rolled to a thickness of 1 mm and the electrode precursor E was rolled to a thickness of 1 mm, and further, on the layer formed from the electrode precursor E, The anion conductive membrane described in Example 1 having a thickness of 0.3 mm was pasted together, and the layer formed from the electrode precursor A was pasted on a tin-plated punched steel sheet to form a negative electrode.
When a charge / discharge test was attempted in the same tripolar cell configuration as in Example 1, the Coulomb efficiency was maintained at 95% or more for 200 cycles or more.

Example 7
To the electrode precursor E of Table 1, 1% by mass of natural graphite as a conductive auxiliary was added to the total mass of the electrode precursor E and kneaded. The obtained electrode precursor was rolled to a thickness of 2 mm and attached to a tinned punched steel plate in the same manner as in Example 1 to form a zinc electrode.
On the other hand, when a charge / discharge test similar to that of Example 1 was attempted, the charge / discharge efficiency was increased by the addition of natural graphite, and a Coulomb efficiency of 95% or more was obtained even after 200 cycles.

Claims (8)

An electrode precursor containing an electrode active material,
The electrode precursor further comprises a polymer and a layered double water compound. The electrode precursor according to claim 1, wherein the electrode active material includes a zinc species, a lithium species, or a cadmium species. The electrode precursor according to claim 1 or 2, wherein the polymer contains at least one selected from the group consisting of a halogen atom, a carboxyl group, a hydroxyl group, and an ether group. The electrode precursor according to claim 1, wherein the polymer includes a fluorine-containing polymer. The electrode precursor according to claim 1, wherein the electrode precursor further contains a conductive additive. An electrode comprising a current collector and an active material layer,
This active material layer is formed using the electrode precursor in any one of Claims 1-5, The electrode characterized by the above-mentioned. In the electrode, the weight ratio of the active material to the layered double water compound contained in the active material layer decreases from the side in contact with the current collector toward the surface of the active material layer opposite to the current collector. The layered double water compound and the active material are distributed in the electrode. A battery comprising the electrode according to claim 6 or 7.