JP7260349B2 - Electrolyte for zinc battery and zinc battery - Google Patents

Description

The present invention relates to electrolytes for zinc batteries and zinc batteries.

Nickel-zinc batteries, air-zinc batteries, silver-zinc batteries and the like are known as zinc batteries. For example, a nickel-zinc battery is an aqueous battery that uses an aqueous electrolyte such as an aqueous potassium hydroxide solution, so it has a high degree of safety, and the combination of zinc and nickel electrodes produces a high electromotive force as an aqueous battery. known to have In addition, nickel-zinc batteries have excellent input/output performance and are low in cost, so they can be applied to industrial applications (e.g., backup power supplies) and automotive applications (e.g., hybrid vehicles). gender is being considered.

The charge/discharge reaction of a nickel-zinc battery proceeds, for example, according to the following formula (discharge reaction: rightward, charge reaction: leftward).
(Positive electrode) 2NiOOH+2H ₂ O+2e ⁻ → 2Ni(OH) ₂ +2OH ⁻
(Negative electrode) Zn+2OH ⁻ → Zn(OH) ₂ +2e ⁻

As shown in the above formula, zinc hydroxide (Zn(OH) ₂ ) is produced by the discharge reaction in zinc batteries. Zinc hydroxide is soluble in the electrolyte, and when zinc hydroxide dissolves in the electrolyte, tetrahydroxide zincate ions ([Zn(OH) ₄ ] ²⁻ ) diffuse into the electrolyte. As a result, the shape change (deformation) of the negative electrode progresses and the distribution of the charging current becomes uneven. In conventional zinc batteries, when dendrites grow due to repeated charging and discharging, the dendrites may penetrate the separator and cause a short circuit. Therefore, various attempts have been made to prevent short circuits due to such dendrites and improve life performance. For example, in Patent Document 1 below, by disposing a cationic organic substance near the surface of the negative electrode, a nickel-plated nonwoven fabric is interposed between the electrodes, whereby a short circuit due to dendrites is disclosed. A technique for preventing this is disclosed.

JP-A-58-126665

By the way, zinc batteries may reach the end of their service life due to short circuits caused by dendrites as well as failure to exhibit discharge capacity due to repeated charging and discharging. In order to improve the life of the zinc battery, it is important to suppress the decrease in the discharge capacity.

Accordingly, an object of the present invention is to provide a zinc battery electrolytic solution capable of suppressing a decrease in discharge capacity of a zinc battery, and a zinc battery including the electrolytic solution.

One aspect of the present invention relates to a zinc battery electrolytic solution containing a cationic surfactant and a nonionic surfactant. According to this electrolytic solution, it is possible to suppress the decrease in the discharge capacity of the zinc battery and improve the life performance of the zinc battery. In addition, this electrolytic solution tends to suppress the formation of dendrites.

In one aspect, the cationic surfactant can be a monoalkyltrimethylammonium salt or a dialkyldimethylammonium salt.

In one aspect, the nonionic surfactant can be a polyoxyethylene alkyl ether or polyoxyethylene alkylphenyl ether.

Another aspect of the present invention relates to a zinc battery comprising the above electrolyte. This zinc battery does not easily decrease in discharge capacity and has excellent life performance.

An object of the present invention is to provide a zinc battery electrolytic solution capable of suppressing a decrease in discharge capacity of a zinc battery, and a zinc battery including the electrolytic solution.

It is a schematic diagram for demonstrating the mechanism of action of the electrolyte solution of one Embodiment. 4 is a graph showing evaluation results of Examples and Comparative Examples.

In this specification, a numerical range indicated using "to" indicates a range including the numerical values before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described stepwise in this specification, the upper limit value or lower limit value of the numerical range in one step can be arbitrarily combined with the upper limit value or lower limit of the numerical range in another step. In the numerical ranges described herein, the upper and lower limits of the numerical ranges may be replaced with the values shown in Experimental Examples. "A or B" may include either A or B, or may include both. The materials exemplified in this specification can be used singly or in combination of two or more unless otherwise specified. As used herein, the amount of each component used in the composition refers to the total amount of the multiple substances present in the composition when there are multiple substances corresponding to each component in the composition, unless otherwise specified. means Further, in this specification, the term "film" or "layer" includes not only a shape structure formed on the entire surface but also a shape structure formed partially when observed as a plan view. be done. In addition, the term "step" as used herein refers not only to an independent step, but also to the term if the desired action of the step is achieved even if it cannot be clearly distinguished from other steps. included.

Preferred embodiments of the present invention are described below. However, the present invention is by no means limited to the following embodiments.

<Electrolyte for zinc batteries>
The electrolytic solution of one embodiment contains a cationic surfactant and a nonionic surfactant. Cationic surfactants and nonionic surfactants are organic compounds or salts thereof that are soluble in the solvent (for example, water) of the electrolytic solution, and may exist dissolved in the electrolytic solution.

A cationic surfactant has a cationic hydrophilic group and a hydrophobic group. Examples of cationic surfactants include quaternary surfactants such as aliphatic amines or salts thereof, alkylamidoamine salts, monoalkyltrimethylammonium salts, dialkyldimethylammonium salts, alkylbenzyldimethylammonium salts, alkylpyridinium salts, and benzethonium chloride salts. ammonium salt-type cationic surfactants; Among these, monoalkyltrimethylammonium salts and dialkyldimethylammonium salts are preferred, and monoalkyltrimethylammonium salts are more preferred.

Monoalkyltrimethylammonium salts and dialkyldimethylammonium salts have, for example, structures represented by the following formula (1).
Formula (1): (R ¹ ) _n N ⁺ (R ² ) _n-4 X ⁻
[In formula (1), n is 1 or 2, R ¹ is a hydrocarbon group having 1 to 20 carbon atoms, and a plurality of R ² are each independently a hydrocarbon group having 1 to 20 carbon atoms. group and X ^- represents an anion. When n is 2, multiple R ^1s may be the same or different. ]

The hydrocarbon group for R ¹ may be linear or branched, saturated or unsaturated, and may contain a cyclic structure such as an alicyclic structure. . The hydrocarbon group for R ¹ is preferably an alkyl group. The hydrocarbon group for R ¹ preferably has 12 to 18 carbon atoms. The hydrocarbon group for ^R2 may be linear or branched and either saturated or unsaturated. The hydrocarbon group for ^R2 is preferably an alkyl group. The number of carbon atoms in the hydrocarbon group for R ² is preferably 1-4. X ^- may be any anion capable of forming a salt with the quaternary ammonium ion of formula (1), for example, halogen ions such as F ^- , Cl ^- , Br ^{- and} I ^- , CH ₃ COO ^- and the like. It may be a carboxylate ion, sulfate ion, phosphate ion, and the like.

Specific examples of monoalkyltrimethylammonium salts include dodecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, tridecyltrimethylammonium bromide, tridecyltrimethylammonium chloride, tetradecyltrimethylammonium bromide, tetradecyltrimethylammonium chloride, and pentadecyltrimethylammonium bromide. , pentadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, heptadecyltrimethylammonium bromide, heptadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide and octadecyltrimethylammonium chloride.

Specific examples of dialkyldimethylammonium salts include didodecyldimethylammonium bromide, didodecyldimethylammonium chloride, ditridecyldimethylammonium bromide, ditridecyldimethylammonium chloride, ditetradecyldimethylammonium bromide, ditetradecyldimethylammonium chloride, dipenta Decyldimethylammonium bromide, dipentadecyldimethylammonium chloride, dihexadecyldimethylammonium bromide, dihexadecyldimethylammonium chloride, diheptadecyldimethylammonium bromide, diheptadecyldimethylammonium chloride, dioctadecyldimethylammonium bromide and dioctadecyldimethylammonium chloride.

The molecular weight of the cationic surfactant is, for example, 90 or more and 500 or less. A cationic surfactant can be used individually by 1 type or in combination of multiple types.

The concentration (content) of the cationic surfactant in the electrolyte is determined from the viewpoint of further improving the effect of suppressing the decrease in discharge capacity due to repeated charging and discharging and the viewpoint of further improving the effect of suppressing dendrite formation. is preferably 0.0005% by mass or more, more preferably 0.001% by mass or more, and still more preferably 0.003% by mass or more, based on the total amount of The concentration (content) of the cationic surfactant in the electrolyte is preferably 2.0% by mass or less, more preferably 2.0% by mass or less, based on the total mass of the electrolyte, from the viewpoint of solubility in the electrolyte. It is 1.0% by mass or less, more preferably 0.5% by mass or less.

A nonionic surfactant has a nonionic hydrophilic group and a hydrophobic group. Examples of nonionic surfactants include polyoxyethylene-containing ester compounds such as polyoxyethylene fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, polyoxyethylene alkyl ethers, and polyoxyethylene alkylphenyl ethers. and polyoxyethylene-containing ether compounds such as Among these, polyoxyethylene alkyl ethers and polyoxyethylene alkylphenyl ethers are preferred, and polyoxyethylene alkylphenyl ethers are more preferred.

Polyoxyethylene alkyl ethers and polyoxyethylene alkylphenyl ethers have structures represented by the following formula (2) or (3), for example.
_Formula (2): ^R3O ( _CH2CH2O ) _mH
[In formula (2), m is an integer of 2 to 60, and R ³ is a hydrocarbon group having 1 to 30 carbon atoms. ]
Formula _{( 3} ) _: ^R4C6H11O ( _CH2CH2O ) _pH
[In formula (3), p is an integer of 2 to 60, and R ⁴ is a hydrocarbon group having 1 to 30 carbon atoms. ]

The hydrocarbon groups for R ³ and R ⁴ may be linear or branched and either saturated or unsaturated. The hydrocarbon groups for R ³ and R ⁴ are preferably alkyl groups. The hydrocarbon group for R ³ preferably has 10 to 18 carbon atoms. The hydrocarbon group of R ⁴ preferably has 4 to 12 carbon atoms. m and p are average degrees of polymerization, preferably 5-12, more preferably 7-10.

Specific examples of polyoxyethylene alkyl ethers include polyoxyethylene decyl ether, polyoxyethylene undecyl ether, polyoxyethylene dodecyl ether, polyoxyethylene tridecyl ether, polyoxyethylene tetradecyl ether, and polyoxyethylene pentadecyl ether. , polyoxyethylene hexadecyl ether, polyoxyethylene heptadecyl ether and polyoxyethylene octadecyl ether.

Specific examples of polyoxyethylene alkylphenyl ether include polyoxyethylene octylphenyl ether and polyoxyethylene nonylphenyl ether.

The molecular weight of the nonionic surfactant is, for example, 100 or more and 1000 or less. A nonionic surfactant can be used individually by 1 type or in combination of multiple types.

The concentration (content) of the nonionic surfactant in the electrolytic solution is preferably 0.5% based on the total amount of the electrolytic solution, from the viewpoint of further improving the effect of suppressing the decrease in discharge capacity due to repeated charging and discharging. 0005% by mass or more, more preferably 0.001% by mass or more, and still more preferably 0.003% by mass or more. The concentration (content) of the nonionic surfactant in the electrolyte is preferably 5.0% by mass or less, more preferably 2, based on the total mass of the electrolyte, from the viewpoint of solubility in the electrolyte. 0% by mass or less, more preferably 1.0% by mass or less.

The mass ratio of the content of cationic surfactant to the content of nonionic surfactant (content of cationic surfactant/content of nonionic surfactant) is the ratio of discharge capacity due to repeated charging and discharging. From the viewpoint of further improving the effect of suppressing the decrease, it may be 0.7 or more, 0.8 or more, or 0.9 or more, and may be 1.3 or less, 1.2 or less, or 1.1 or less.

The electrolyte of the electrolytic solution is usually a basic compound, and examples thereof include alkali metal hydroxides such as potassium hydroxide (KOH), sodium hydroxide (NaOH) and lithium hydroxide (LiOH). These basic compounds may be ionized in an aqueous solution, or may exist as salts.

The concentration (content) of the electrolyte in the electrolytic solution is 12% by mass or more, 15% by mass or more, or It may be 18% by mass or more, and may be 35% by mass or less, 30% by mass or less, or 28% by mass or less.

The solvent of the electrolytic solution is, for example, water (ion-exchanged water, etc.).

The electrolytic solution may further contain components other than the above, such as potassium phosphate, potassium fluoride, potassium carbonate, sodium phosphate, sodium fluoride, lithium hydroxide, zinc oxide, antimony oxide, and titanium dioxide.

The electrolytic solution of the above embodiment is a zinc battery electrolytic solution incorporated in a zinc battery (for example, a zinc secondary battery). Zinc batteries include nickel-zinc batteries, air-zinc batteries, and the like. Zinc batteries can use zinc anodes.

According to the electrolytic solution of the above embodiment, it is possible to suppress the decrease in the discharge capacity of the zinc battery and improve the life performance of the zinc battery. Although the reason why such an effect is obtained is not clear, in conventional zinc batteries, it is difficult for the electrolyte to diffuse evenly on the surface of the active material (zinc component) of the zinc electrode, and the active material that does not come into contact with the electrolyte is It is thought that the discharge capacity decreases due to deactivation, but when using the electrolyte solution of the present embodiment, the above two surfactants improve the diffusion of the electrolyte solution to the surface of the active material. , it is speculated that the decrease in discharge capacity is suppressed. A detailed description will be given below with reference to the schematic diagram of FIG.

First, as shown in FIG. 1(a), in the zinc battery, the active material 2 (e.g., ZnO) constituting the surface of the zinc electrode 1 is negatively charged, and the cationic hydrophilicity of the cationic surfactant 3 The group c1 is adsorbed (electrostatically adsorbed) to the negatively charged active material, and the hydrophobic group c2 of the cationic surfactant 3 faces outward (electrolyte side). Here, since the hydrophobic group c2 of the cationic surfactant 3 and the hydrophobic group n2 of the nonionic surfactant 4 have a high affinity, as shown in FIG. The group n2 is adsorbed to the hydrophobic group c2 of the cationic surfactant, and the nonionic hydrophilic group n1 faces outward (toward the electrolyte). As a result, the hydrophilicity of the surface of the zinc electrode 1 is improved, and the electrolytic solution easily penetrates into the electrode material, thereby improving the diffusibility of the electrolytic solution to the surface of the active material 2 and reducing the discharge capacity. is presumed to be suppressed.

Furthermore, in the electrolytic solution of the above-described embodiment, the cationic hydrophilic group C1 of the cationic surfactant is adsorbed to the negatively charged surface S of the zinc electrode, thereby smoothing the potential, so that the generation of dendrites is also suppressed. tend to

A nickel-zinc battery will be described below as an example of a zinc battery in which the electrolytic solution of the above embodiment is used.

<Nickel zinc battery>
A nickel-zinc battery (for example, a nickel-zinc secondary battery) of the present embodiment includes, for example, a battery case, an electrode group (for example, an electrode plate group) and an electrolytic solution housed in the battery case. The zinc battery of this embodiment may be either post-formation or non-formation.

The electrode group includes, for example, a positive electrode (eg, positive electrode plate), a negative electrode (eg, negative electrode plate), and a separator. The positive electrode and the negative electrode are adjacent to each other with one or more separators interposed therebetween. That is, one or more separators are provided between the adjacent positive electrode and negative electrode. The electrode group may comprise a plurality of positive electrodes, negative electrodes and separators. When the electrode group includes a plurality of positive electrodes and/or a plurality of negative electrodes, the positive electrodes and the negative electrodes may be alternately laminated with separators interposed therebetween. The plurality of positive electrodes and the plurality of negative electrodes may be connected by straps, for example. The positive electrode of this embodiment is a nickel (Ni) electrode, and the negative electrode is a zinc (Zn) electrode. That is, in the following description, "positive electrode" may be replaced with "nickel electrode", and "negative electrode" may be replaced with "zinc electrode". The same applies to descriptions such as “positive electrode material” and “negative electrode material”.

The positive electrode includes, for example, a positive electrode current collector and a positive electrode material supported by the positive electrode current collector. The positive electrode may be formed before or after formation.

The cathode current collector constitutes a conductive path for current from the cathode material. The positive electrode current collector has, for example, a plate shape, a sheet shape, or the like. The positive electrode current collector may be a current collector having a three-dimensional mesh structure made of foamed metal, expanded metal, punched metal, metal fiber felt, or the like. The positive electrode current collector is made of a material having electrical conductivity and alkali resistance. Examples of such materials include materials that are stable even at the reaction potential of the positive electrode (materials that have a nobler oxidation-reduction potential than the reaction potential of the positive electrode, materials that form a protective film such as an oxide film on the substrate surface in an alkaline aqueous solution, and (such as a material that stabilizes by In the positive electrode, a decomposition reaction of the electrolyte progresses as a side reaction to generate oxygen gas, and a material having a high oxygen overvoltage is preferable in that it can suppress the progress of such a side reaction. Specific examples of materials constituting the positive electrode current collector include platinum; nickel (foamed nickel, etc.); metal materials plated with metal such as nickel (copper, brass, steel, etc.). Among these, a positive electrode current collector made of foamed nickel is preferably used. From the viewpoint of further improving the high-rate discharge performance, it is preferable that at least the portion of the positive electrode current collector that supports the positive electrode material (positive electrode material supporting portion) is made of foamed nickel.

The positive electrode material is, for example, layered. That is, the positive electrode may have a positive electrode material layer. The positive electrode material layer may be formed on the positive electrode current collector. When the positive electrode material supporting portion of the positive electrode current collector has a three-dimensional mesh structure, the positive electrode material may be filled between the meshes of the current collector to form a positive electrode material layer.

The positive electrode material contains a positive electrode active material (electrode active material) containing nickel. Examples of the positive electrode active material include nickel oxyhydroxide (NiOOH) and nickel hydroxide. The positive electrode material contains, for example, nickel oxyhydroxide in a fully charged state and nickel hydroxide in a discharged state. The content of the positive electrode active material may be, for example, 50 to 95% by mass based on the total mass of the positive electrode material.

The positive electrode material may further contain components other than the positive electrode active material as additives. Additives include binders (binding agents), conductive agents, expansion inhibitors, and the like.

Examples of binders include hydrophilic or hydrophobic polymers. Specifically, for example, carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), hydroxypropyl methyl cellulose (HPMC), sodium polyacrylate (SPA), fluorine-based polymers (polytetrafluoroethylene (PTFE), etc.) and the like are used as binders. can be used as The binder content is, for example, 0.01 to 5 parts by mass with respect to 100 parts by mass of the positive electrode active material.

Examples of conductive agents include cobalt compounds (metallic cobalt, cobalt oxide, cobalt hydroxide, etc.). The content of the conductive agent is, for example, 1 to 20 parts by mass with respect to 100 parts by mass of the positive electrode active material.

Zinc oxide etc. are mentioned as an expansion inhibitor. The content of the expansion inhibitor is, for example, 0.01 to 5 parts by mass with respect to 100 parts by mass of the positive electrode active material.

The negative electrode includes a negative electrode current collector (current collector) and a negative electrode material (electrode material) supported by the negative electrode current collector. The negative electrode may be formed before or after chemical conversion.

The negative electrode current collector constitutes a conductive path for current from the negative electrode material. The negative electrode current collector has, for example, a plate shape, a sheet shape, or the like. The negative electrode current collector may be a current collector having a three-dimensional mesh structure made of foamed metal, expanded metal, punched metal, metal fiber felt, or the like. The negative electrode current collector is made of a material having electrical conductivity and alkali resistance. Examples of such materials include materials that are stable even at the reaction potential of the negative electrode (materials that have a nobler oxidation-reduction potential than the reaction potential of the negative electrode, materials that form a protective film such as an oxide film on the substrate surface in an alkaline aqueous solution, and (such as a material that stabilizes by In the negative electrode, a decomposition reaction of the electrolytic solution progresses as a side reaction to generate hydrogen gas, and a material having a high hydrogen overvoltage is preferable in that the progress of such a side reaction can be suppressed. Specific examples of materials constituting the negative electrode current collector include zinc; lead; tin; metal materials plated with metal such as tin (copper, brass, steel, nickel, etc.).

The negative electrode material is, for example, layered. That is, the negative electrode may have a negative electrode material layer. The negative electrode material layer may be formed on the negative electrode current collector. When the portion of the negative electrode current collector that supports the negative electrode material has a three-dimensional network structure, the negative electrode material may be filled between the meshes of the current collector to form a negative electrode material layer.

The negative electrode material contains a negative electrode active material (electrode active material) containing zinc. Examples of negative electrode active materials include metal zinc, zinc oxide, and zinc hydroxide. The negative electrode active material may contain one of these components alone, or may contain a plurality of them. The negative electrode material contains, for example, metallic zinc in a fully charged state, and zinc oxide and zinc hydroxide in a discharged state. The negative electrode active material is, for example, particulate. That is, the negative electrode material may contain at least one selected from the group consisting of metallic zinc particles, zinc oxide particles and zinc hydroxide particles. The content of the negative electrode active material is, for example, 50 to 95% by mass based on the total mass of the negative electrode material.

The negative electrode material may contain additives. Examples of additives include binders and conductive agents.

Binders include polytetrafluoroethylene, hydroxyethyl cellulose, polyethylene oxide, polyethylene, polypropylene and the like. The content of the binder may be, for example, 0.5 to 10 parts by mass with respect to 100 parts by mass of the negative electrode active material.

Examples of conductive agents include indium compounds (indium oxide, etc.). The content of the conductive agent is, for example, 1 to 20 parts by mass with respect to 100 parts by mass of the negative electrode active material.

The separator may be, for example, a separator having a plate shape, a sheet shape, or the like. Examples of separators include polyolefin-based microporous membranes, nylon-based microporous membranes, oxidation-resistant ion-exchange resin membranes, cellophane-based recycled resin membranes, inorganic-organic separators, and polyolefin-based nonwoven fabrics. The separator may be processed into a bag shape so as to accommodate the positive electrode and/or the negative electrode. In this case, the positive electrode and/or the negative electrode may be housed in a separator. A separator may be used alone or in combination of two or more.

The manufacturing method of the nickel-zinc battery described above includes, for example, a component manufacturing step for obtaining the component members of the zinc battery, and an assembling step for assembling the component members to obtain the zinc battery. In the component manufacturing process, at least electrodes (a positive electrode and a negative electrode) are obtained.

For the electrode, for example, an electrode material paste (paste-like electrode material) is obtained by adding a solvent (e.g., water) to the raw materials of the electrode materials (positive electrode material and negative electrode material) and kneading, and then the electrode material paste is obtained. can be obtained by forming an electrode material layer using

Examples of the raw material for the positive electrode material include raw materials for the positive electrode active material (for example, nickel hydroxide), additives (for example, the binder), and the like. Raw materials for negative electrode materials include raw materials for negative electrode active materials (eg, metallic zinc, zinc oxide, and zinc hydroxide), additives (eg, the binder), and the like.

As a method of forming the electrode material layer, for example, there is a method of obtaining the electrode material layer by applying or filling an electrode material paste to a current collector and then drying it. If necessary, the electrode material layer may be densified by pressing or the like.

In the assembly process, for example, the positive electrodes and the negative electrodes obtained in the component manufacturing process are alternately laminated with separators interposed therebetween, and then the positive electrodes and the negative electrodes are connected with straps to form an electrode group. Next, after placing this electrode group in a container, a cover is adhered to the upper surface of the container to obtain an unformed zinc battery (nickel-zinc battery).

Subsequently, after pouring the electrolytic solution into the container of the unformed zinc battery, the battery is left for a certain period of time. Then, a zinc battery (nickel-zinc battery) is obtained by chemical conversion by charging under predetermined conditions. Formation conditions can be adjusted according to the properties of the electrode active materials (positive electrode active material and negative electrode active material).

An example of a nickel-zinc battery (for example, a nickel-zinc secondary battery) in which the positive electrode is a nickel electrode has been described above. Alternatively, it may be a silver-zinc battery (for example, a silver-zinc secondary battery) in which the positive electrode is a silver oxide electrode.

As the air electrode of the zinc-air battery, a known air electrode used for zinc-air batteries can be used. The cathode includes, for example, a cathode catalyst, an electronically conductive material, and the like. As the air electrode catalyst, an air electrode catalyst that also functions as an electronically conductive material can be used.

As the air electrode catalyst, one that functions as a positive electrode in a zinc-air battery can be used, and various air electrode catalysts that can use oxygen as a positive electrode active material can be used. As the air electrode catalyst, carbon-based materials (graphite, etc.) having redox catalytic function, metal materials (platinum, nickel, etc.) having redox catalytic function, inorganic oxide materials (perovskite oxide, etc.) having redox catalytic function , manganese dioxide, nickel oxide, cobalt oxide, spinel oxide, etc.). Although the shape of the air electrode catalyst is not particularly limited, it may be particulate, for example. The amount of the air electrode catalyst used in the air electrode may be 5 to 70% by volume, 5 to 60% by volume, or 5 to 50% by volume with respect to the total amount of the air electrode. good too.

As the electronically conductive material, a material that has electrical conductivity and enables electronic conduction between the air electrode catalyst and the separator can be used. Examples of electron conductive materials include carbon blacks such as ketjen black, acetylene black, channel black, furnace black, lamp black, and thermal black; graphites such as natural graphite such as flake graphite, artificial graphite, and expanded graphite; conductive fibers such as carbon fibers and metal fibers; metal powders such as copper, silver, nickel and aluminum; organic electronic conductive materials such as polyphenylene derivatives; The shape of the electron conductive material may be particulate or other shapes. The electronically conductive material is preferably used in a form that provides a continuous phase in the thickness direction in the air electrode. For example, the electronically conductive material may be a porous material. Further, the electronically conductive material may be in the form of a mixture or composite with the air electrode catalyst, and as described above, may be the air electrode catalyst that also functions as an electronically conductive material. The amount of the electronically conductive material used in the air electrode may be 10 to 80% by volume, 15 to 80% by volume, or 20 to 80% by volume with respect to the total amount of the air electrode. may

As the silver oxide electrode of the silver-zinc battery, a known silver oxide electrode used for silver-zinc batteries can be used. The silver oxide electrode contains, for example, silver (I) oxide.

EXAMPLES The content of the present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

(Example 1)
[Preparation of electrolytic solution]
In ion-exchanged water, potassium hydroxide (KOH) and lithium hydroxide (LiOH) as electrolytes, and tetradecyltrimethylammonium bromide (special grade reagent, manufactured by Fujifilm Wako Pure Chemical Co., Ltd.) as a cationic surfactant, Triton-X100 (manufactured by Sigma-Aldrich Japan LLC), which is a nonionic surfactant, is added and mixed to form an electrolytic solution (potassium hydroxide concentration: 25% by mass, sodium hydroxide concentration: 1% by mass, cationic interface active agent concentration: 0.005% by mass, nonionic surfactant concentration: 0.005% by mass).

[Preparation of positive electrode]
A grid body made of foamed nickel with a porosity of 95% was prepared, and the grid body was pressure-molded to obtain a positive electrode current collector. Then, predetermined amounts of cobalt-coated nickel hydroxide powder, metallic cobalt, cobalt hydroxide, yttrium oxide, CMC, PTFE, and ion-exchanged water were weighed and mixed, and the mixture was stirred to prepare a positive electrode material paste. At this time, the mass ratio of the solid content was set to "nickel hydroxide: metallic cobalt: yttrium oxide: cobalt hydroxide: CMC: PTFE = 88: 10.3: 1: 0.3: 0.3: 0.1". It was adjusted. The water content of the positive electrode material paste was adjusted to 27.5% by mass based on the total mass of the positive electrode material paste. Next, the positive electrode material paste was applied to the positive electrode material supporting portion of the positive electrode current collector, and then dried at 80° C. for 30 minutes. After that, pressure molding was performed using a roll press to obtain an unformed positive electrode having a positive electrode material layer.

[Preparation of negative electrode]
As a negative electrode current collector, a tin-plated steel plate punching metal having a porosity of 60% was prepared. Then, predetermined amounts of zinc oxide, metallic zinc, HEC, and ion-exchanged water were weighed and mixed, and the obtained mixture was stirred to prepare a negative electrode material paste. At this time, the mass ratio of the solid content was adjusted to "zinc oxide:metal zinc:HEC=85:11.5:3.5". As the HEC, AV-15F (trade name) manufactured by Sumitomo Seika Co., Ltd. was used. The water content of the negative electrode material paste was adjusted to 32.5% by mass based on the total mass of the negative electrode material paste. Next, the negative electrode material paste was applied onto the negative electrode current collector and then dried at 80° C. for 30 minutes. After that, pressure molding was performed using a roll press to obtain an unformed negative electrode having a negative electrode material (negative electrode material layer).

[Preparation of separator]
For the separator, UP3355 (manufactured by Ube Industries, Ltd., trade name, air permeability: 440 sec/100 mL) as a microporous membrane, and non-woven fabric (manufactured by Nippon Kodoshi Kogyo Co., Ltd., trade name: VL-100, air permeability) as a non-woven fabric degree: 0.3 sec/100 mL) were used respectively. The microporous membrane was hydrophilized with a surfactant Triton-X100 (manufactured by Sigma-Aldrich Japan LLC) before battery assembly. Hydrophilization was performed by immersing the microporous membrane in an aqueous solution containing 1% by mass of Triton-X100 for 24 hours and then drying at room temperature for 1 hour. The air permeability of the microporous membrane indicates the value after hydrophilization treatment. Further, the microporous membrane was cut into a predetermined size, folded in half, and heat-sealed on the sides to form a bag. The nonwoven fabric was cut into a predetermined size and used.

[Fabrication of nickel-zinc battery]
A positive electrode (unformed positive electrode) and a negative electrode (unformed negative electrode) were placed in a bag-shaped microporous membrane. After stacking the positive electrode housed in the bag-shaped microporous membrane, the negative electrode housed in the bag-shaped microporous membrane, and the nonwoven fabric, the electrode plates of the same polarity are connected with a strap to form an electrode group (electrode plate group) were prepared. The electrode group consisted of 11 positive electrodes and 12 negative electrodes, and one non-woven fabric was arranged between the positive electrode and the negative electrode (between the microporous film on the positive electrode side and the microporous film on the negative electrode side). After placing this electrode group in a battery case, a cover was adhered to the upper surface of the battery case, and the electrolytic solution was poured into the battery case to obtain an unformed nickel-zinc battery. Thereafter, charging was performed at 0.8 A for 15 hours to produce a nickel-zinc battery with a nominal capacity of 8 Ah.

(Comparative example 1)
In the preparation of the electrolytic solution, no nonionic surfactant was used, and the amount of cationic surfactant used was adjusted so that the concentration of the cationic surfactant in the electrolytic solution was 0.01% by mass. An electrolytic solution was prepared in the same manner as in Example 1, except for the change. A nickel-zinc battery was produced in the same manner as in Example 1, except that the electrolytic solution thus obtained was used.

(Comparative example 2)
In the preparation of the electrolytic solution, no cationic surfactant was used, and the amount of nonionic surfactant used was adjusted so that the concentration of the nonionic surfactant in the electrolytic solution was 0.01% by mass. An electrolytic solution was prepared in the same manner as in Example 1, except for the change. A nickel-zinc battery was produced in the same manner as in Example 1, except that the electrolytic solution thus obtained was used.

(Comparative Example 3)
An electrolytic solution was prepared in the same manner as in Example 1, except that the cationic surfactant and the nonionic surfactant were not used in the preparation of the electrolytic solution. A nickel-zinc battery was produced in the same manner as in Example 1, except that the electrolytic solution thus obtained was used.

<Cycle test>
A test (25° C.) in which one cycle of the following operation was performed was performed on the nickel-zinc batteries of the above Examples and Comparative Examples, and the discharge capacity of each cycle was measured. Then, the maintenance rate (%) of the discharge capacity at each cycle with respect to the discharge capacity at the first cycle was calculated. The results are shown in Table 1 and FIG. Note that the unit "C" described below relatively represents the magnitude of the current when the rated capacity is discharged from the fully charged state at a constant current. The unit "C" means "discharge current value (A)/battery capacity (Ah)". For example, the current that can discharge the rated capacity in 1 hour is expressed as "1C", and the current that can be discharged in 2 hours is expressed as "0.5C".
・8A (1C), 1.9V constant voltage charging (charging ends when the current decays to 40mA (0.05C))
・Constant current discharge at 2.5A (0.25C) until the battery voltage reaches 1.1V

Claims (2)

A zinc battery electrolytic solution containing a cationic surfactant and a nonionic surfactant ,
Containing tetradecyltrimethylammonium bromide as the cationic surfactant,
Containing polyoxyethylene alkylphenyl ether as the nonionic surfactant,
A zinc battery electrolytic solution, wherein the mass ratio of the content of the cationic surfactant to the content of the nonionic surfactant is 0.7 or more and 1.3 or less. A zinc battery comprising the electrolyte of claim 1 .

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