Zinc battery anode and zinc battery

Abstract

To improve the lifespan performance of a zinc battery.SOLUTION: In a negative electrode for a zinc battery having a negative electrode current collector and a negative electrode material supported on the negative electrode current collector, the negative electrode material contains a negative electrode active material containing zinc and a low molecular weight organic compound having an ether bond.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a negative electrode for a zinc battery and a zinc battery. [Background technology]

[0002] Known zinc batteries include, for example, nickel-zinc batteries, air-zinc batteries, and silver-zinc batteries. Nickel-zinc batteries are aqueous batteries that contain an aqueous electrolyte, such as an aqueous potassium hydroxide solution. Therefore, nickel-zinc batteries are known to have high safety and, due to the combination of zinc electrodes and nickel electrodes, to have a high electromotive force for an aqueous battery. Nickel-zinc batteries have excellent input / output performance and low cost, so their applicability to industrial applications such as backup power sources and automotive applications such as hybrid vehicles is being considered.

[0003] In the case of negative electrode materials for zinc batteries, in order to improve the formability of the negative electrode material layer or the energy density, the use of various additives in addition to negative electrode active materials containing zinc has been investigated (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-160793 Summary of the Invention [Problem to be solved by the invention]

[0005] Further improvements in lifespan performance are required for zinc batteries such as nickel-zinc batteries. One object of the present disclosure is to improve the life performance of zinc batteries. [Means for solving the problem]

[0006] One aspect of the negative electrode for a zinc battery according to the present disclosure has a negative electrode current collector and a negative electrode material supported on the negative electrode current collector, and the negative electrode material contains a negative electrode active material containing zinc and a low-molecular-weight organic compound having an ether bond. One aspect of the zinc battery according to the present disclosure includes a positive electrode, the negative electrode for a zinc battery described above, and an electrolytic solution.

Advantages of the Invention

[0007] A zinc battery including the negative electrode for a zinc battery according to the present disclosure has excellent life performance.

Modes for Carrying Out the Invention

[0008] In this specification, when the units of the numerical values described before and after "~" indicating a numerical range are the same, unless otherwise specified, the unit of the numerical value described before "~" is omitted. For example, "50% by mass to 99% by mass" is described as "50 to 99% by mass". In this specification, the numerical range indicated by "N1 to N2" means N1 or more and N2 or less when N1 < N2, and means N2 or more and N1 or less when N1 > N2. N1 and N2 are each arbitrary numerical values.

[0009] In this specification, when a plurality of lower limit values and upper limit values are respectively described for the numerical range of an element, the numerical range obtained by arbitrarily combining a value arbitrarily selected from the described lower limit values and a value arbitrarily selected from the described upper limit values is also regarded as being described. In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value of the numerical range of a certain step can be arbitrarily combined with the upper limit value or the lower limit value of the numerical range of another step. In the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

[0010] In this specification, "A or B" may mean either one of A and B or both A and B.

[0011] Unless otherwise specified, each component described in this specification may be used alone or in combination of two or more. In this specification, for example, the content or amount of each component in a negative electrode material means the total content or amount of the multiple substances present in the negative electrode material when the negative electrode material contains multiple substances corresponding to that component, unless otherwise specified.

[0012] In this specification, the terms "layer" or "film" provided on an object include not only a shaped structure formed on the entire surface of the object when the object is observed in a plan view, but also a shaped structure formed on a part of the object.

[0013] [Zinc battery anode] The negative electrode for a zinc battery (hereinafter sometimes simply referred to as "negative electrode") of the present disclosure has a negative electrode current collector and a negative electrode material supported on the negative electrode current collector. The negative electrode material may be disposed on at least one main surface of the negative electrode current collector, or may be disposed on both main surfaces of the negative electrode current collector. The negative electrode may be either before or after chemical formation.

[0014] The negative electrode current collector forms a conductive path for current from the negative electrode material. The negative electrode current collector may have a shape such as a flat plate or a sheet. The negative electrode current collector may be a current collector with a three-dimensional mesh structure made of, for example, foamed metal, expanded metal, punched metal, or metal fiber felt.

[0015] The negative electrode current collector may be made of, for example, a material that is conductive and alkali-resistant. Examples of such materials include materials that are stable even at the reaction potential of the negative electrode. Examples of such materials include materials with a redox potential higher than the reaction potential of the negative electrode, and materials that form a protective film such as an oxide film on the substrate surface in an alkaline aqueous solution to stabilize the surface. Furthermore, at the negative electrode, a decomposition reaction of the electrolyte may occur as a side reaction, generating hydrogen gas. Materials with a high hydrogen overvoltage are preferred because they can suppress the progression of such side reactions.

[0016] Specific examples of materials constituting the negative electrode current collector include zinc, lead, tin, and metal-plated metal materials. For example, tin is used for the metal plating. Examples of metal materials include copper, brass, steel, and nickel. The metal plating may be applied to at least a portion of the surface of the metal material.

[0017] The thickness of the negative electrode current collector is preferably 0.01 to 1.0 mm, more preferably 0.05 to 0.8 mm, still more preferably 0.08 to 0.5 mm, and particularly preferably 0.1 to 0.3 mm.

[0018] The thickness of the negative electrode is preferably 0.1 to 1.5 mm, more preferably 0.1 to 1.0 mm, even more preferably 0.2 to 0.8 mm, and particularly preferably 0.3 to 0.5 mm, from the viewpoint of easily achieving both excellent battery life performance and excellent high-rate discharge performance. The thickness of the negative electrode means the total thickness of the negative electrode (for example, the thickness after filling the negative electrode current collector with the negative electrode material and pressing it with a roller or the like to a predetermined density).

[0019] The negative electrode material may be, for example, layered. That is, the negative electrode may have a negative electrode material layer. The negative electrode material layer may be formed on a negative electrode current collector. When the portion of the negative electrode current collector that supports the negative electrode material has a three-dimensional mesh structure, the negative electrode material may be filled between the meshes of that portion to form the negative electrode material layer.

[0020] The negative electrode material contains a negative electrode active material containing zinc and a low molecular weight organic compound having an ether bond. Each component that is or can be contained in the negative electrode material will be described below.

[0021] <Negative electrode active material containing zinc> Examples of zinc-containing negative electrode active materials include metallic zinc, zinc oxide, and zinc hydroxide. The negative electrode active material may be, for example, in the form of particles. That is, examples of negative electrode active materials include metallic zinc particles, zinc oxide particles, and zinc hydroxide particles.

[0022] In one embodiment, the negative electrode material contains metallic zinc when the battery is in a fully charged state, and contains at least one selected from the group consisting of zinc oxide and zinc hydroxide when the battery is in an end-of-discharge state. The negative electrode material contains at least one negative electrode active material containing zinc, and may contain two or more types.

[0023] The content of the zinc-containing negative electrode active material is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more, based on the total mass of the negative electrode material, and is preferably 99% by mass or less, more preferably 98% by mass or less, even more preferably 96% by mass or less, and particularly preferably 95% by mass or less. Such a negative electrode material tends to easily achieve both excellent battery life performance and excellent high-rate discharge performance. The content of the zinc-containing negative electrode active material is preferably, for example, 50 to 99% by mass, 60 to 98% by mass, 70 to 96% by mass, or 80 to 95% by mass, based on the total mass of the negative electrode material.

[0024] <Low molecular weight organic compounds with ether bonds> The negative electrode material contained in the negative electrode for a zinc battery of the present disclosure contains a low molecular weight organic compound having an ether bond (hereinafter also referred to as a "low molecular weight ether compound"). In this specification, the term "ether bond" refers to a compound having an R A -OR B In the formula, R A and R B each independently represents an organic group, and R A and R B may be bonded to each other to form a ring. An ether bond may be contained within the ring. A The atom bonded to the "-O-" in R is usually a carbon atom. B The atom bonded to the "-O-" in the formula (I) is usually a carbon atom.

[0025] A zinc battery equipped with a negative electrode having such a negative electrode material has excellent life performance, particularly excellent life performance in float charging applications. Although the reason for this is unclear, it is speculated that one factor is that the oxygen atoms contained in the low molecular weight ether compound can interact with zinc ions to reduce the uneven progress of the zinc dissolution or precipitation reaction that occurs during charge and discharge at the negative electrode. However, the contents of the present disclosure are not limited in any way by the speculated reason.

[0026] Examples of components constituting a zinc battery include a negative electrode material and an electrolyte. Compared with zinc batteries whose electrolyte contains a low molecular weight ether compound, zinc batteries whose negative electrode material contains a low molecular weight ether compound tend to have better life performance in float charging applications. While the reason for this is unclear, it is speculated that when the negative electrode material contains a low molecular weight ether compound, the oxidative decomposition of the low molecular weight ether compound at the positive electrode can be suppressed, thereby allowing the effect of adding the low molecular weight ether compound to last for a longer period of time and achieving the above-mentioned effect more uniformly throughout the negative electrode material. However, in the zinc battery disclosed below, the electrolyte may further contain a low molecular weight ether compound. Furthermore, the content of the present disclosure is in no way limited by the above speculation.

[0027] Float charging is a charging method that maintains a battery in a fully charged state or a state close to being fully charged by continuously applying a constant voltage to the battery. Depending on the battery's application, it may be desirable for the battery to always be maintained in a fully charged state or a state close to being fully charged. Such applications include standby applications, such as uninterruptible power supplies (UPS), backup power sources for servers or elevators, power sources for disaster prevention or security systems, and power sources for emergency equipment.

[0028] The molecular weight of the low molecular weight ether compound is preferably 1000 or less, more preferably 800 or less, even more preferably 600 or less, still more preferably 500 or less, and particularly preferably 400 or less, and is preferably 40 or more, more preferably 60 or more, even more preferably 70 or more, still more preferably 80 or more, and particularly preferably 100 or more. The molecular weight of the low molecular weight ether compound is preferably, for example, 40 to 1000, 60 to 800, 70 to 600, 80 to 500, or 100 to 400. By using a low molecular weight ether compound having a molecular weight equal to or less than the above upper limit, it is likely possible to improve the life performance of the zinc battery while suppressing a decrease in output.

[0029] The number of ether bonds contained in the low molecular weight ether compound is 1 or more, and from the viewpoint of battery life performance, it is preferably 1 to 15, more preferably 1 to 10, even more preferably 1 to 8, still more preferably 1 to 6, particularly preferably 1 to 4, and most preferably 1 to 3.

[0030] Examples of low molecular weight ether compounds include sugars, glycol ether compounds, epoxy compounds, and crown ether compounds. Among these, from the viewpoint of improving the life performance of zinc batteries, particularly the float life performance of zinc batteries, at least one selected from the group consisting of sugars and glycol ether compounds is preferred, and sugars are more preferred.

[0031] Examples of carbohydrates include monosaccharides, disaccharides, trisaccharides, and polysaccharides (excluding sugars that fall into the disaccharide or trisaccharide category). Examples of monosaccharides include glucose, fructose, galactose, arabinose, ribose, mannose, xylose, sorbose, rhamnose, fucose, and ribonucleotides, as well as hydrates thereof. Monosaccharides that have an open ring and a chain structure are also included in low-molecular-weight ether compounds. Examples of disaccharides include sucrose, maltose, trehalose, cellobiose, gentiobiose, lactose, and melibiose, as well as hydrates thereof. Examples of trisaccharides include kestose, melezitose, gentianose, raffinose, and melezitose, as well as hydrates thereof. Polysaccharides include, for example, cyclodextrins (eg, α-cyclodextrin), fungytetraose, and stachyose.

[0032] Among the carbohydrates, from the viewpoint of the battery life performance, at least one selected from the group consisting of monosaccharides, disaccharides, and trisaccharides is preferred, at least one selected from the group consisting of monosaccharides and disaccharides is more preferred, at least one selected from the group consisting of glucose and sucrose is even more preferred, and sucrose is particularly preferred.

[0033] Among the carbohydrates, non-reducing sugars are preferred from the viewpoint of battery life performance. Non-reducing sugars refer to sugars that do not have a free reducing group, as opposed to reducing sugars (sugars that have a free aldehyde or ketone group, or a hemiacetal-linked aldehyde or ketone group) (see Chemical Dictionary, Tokyo Kagaku Dojin Co., Ltd., 1st edition). In other words, non-reducing sugars refer to sugars that do not have either a free aldehyde or ketone group or a hemiacetal-linked aldehyde or ketone group. The non-reducing sugar may be in the form of a hydrate.

[0034] Examples of non-reducing sugars include disaccharides such as sucrose, trehalose, and hydrates thereof; trisaccharides such as kestose, melezitose, gentianose, raffinose, melezitose, and hydrates thereof; and polysaccharides such as α-cyclodextrin, fungitetraose, stachyose, and hydrates thereof. From the viewpoint of battery life performance, the non-reducing sugar is preferably a disaccharide, more preferably at least one selected from the group consisting of sucrose, trehalose, and hydrates thereof, and even more preferably sucrose.

[0035] The glycol ether compound is preferably a compound represented by formula (1). R 1 -O-(AO) n -R 2 ···(1) In formula (1), A is an alkanediyl group, and R 1 and R 2 are each independently a hydrogen atom or an organic group, and n is an integer of 1 or more. However, when n=1, R 1 and R 2 At least one of the groups is an organic group.

[0036] A is an alkanediyl group, preferably an alkanediyl group having 1 to 10 carbon atoms, more preferably 2 to 8 carbon atoms, still more preferably 2 to 6 carbon atoms, and particularly preferably 2 to 4 carbon atoms. A is preferably an ethanediyl group or a propanediyl group.

[0037] R 1 and R 2are each independently a hydrogen atom or an organic group. Examples of the organic group include an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, and an aryl group, and these groups may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, a carboxy group, a carboxylate group, an alkoxide group, an epoxy group, an ether group, an ester group, a ketone group, and an aldehyde group. The number of carbon atoms in the organic group is preferably 10 or less, more preferably 8 or less, even more preferably 6 or less, and particularly preferably 4 or less.

[0038] Among the organic groups, alkyl groups are preferred. The alkyl groups may be linear or branched. As the alkyl group, alkyl groups having 1 to 10 carbon atoms are preferred, alkyl groups having 1 to 8 carbon atoms are more preferred, alkyl groups having 1 to 6 carbon atoms are even more preferred, and alkyl groups having 1 to 4 carbon atoms are particularly preferred. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a t-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group, and among these, a methyl group is preferred.

[0039] R 1 and R 2 may be the same or different, and are preferably the same organic group, more preferably the same alkyl group, and even more preferably a methyl group.

[0040] n is an integer of 1 or more, preferably an integer of 1 to 10, more preferably an integer of 2 to 10, even more preferably an integer of 2 to 8, still more preferably an integer of 2 to 6, and particularly preferably an integer of 2 to 4.

[0041] Examples of glycol ether compounds include alkylene glycol monoalkyl ethers, alkylene glycol dialkyl ethers, dialkylene glycols, dialkylene glycol monoalkyl ethers, dialkylene glycol dialkyl ethers, trialkylene glycols, trialkylene glycol monoalkyl ethers, trialkylene glycol dialkyl ethers, tetraalkylene glycols, tetraalkylene glycol monoalkyl ethers, tetraalkylene glycol dialkyl ethers, polyalkylene glycols, polyalkylene glycol monoalkyl ethers, and polyalkylene glycol dialkyl ethers.

[0042] The above-mentioned "alkylene" in the examples of glycol ether compounds is preferably "ethylene" or "propylene." The above-mentioned "alkyl" in the examples of glycol ether compounds is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, still more preferably an alkyl group having 1 to 6 carbon atoms, and particularly preferably an alkyl group having 1 to 4 carbon atoms.

[0043] Among glycol ether compounds, from the viewpoint of battery life performance, Ethylene glycol monoalkyl ethers, ethylene glycol dialkyl ethers, diethylene glycol, diethylene glycol monoalkyl ethers, diethylene glycol dialkyl ethers, triethylene glycol, triethylene glycol monoalkyl ethers, triethylene glycol dialkyl ethers, tetraethylene glycol, tetraethylene glycol monoalkyl ethers, tetraethylene glycol dialkyl ethers, polyethylene glycol, polyethylene glycol monoalkyl ethers, and polyethylene glycol dialkyl ethers are preferred; Ethylene glycol monoalkyl ethers, ethylene glycol dialkyl ethers, diethylene glycol monoalkyl ethers, diethylene glycol dialkyl ethers, triethylene glycol monoalkyl ethers, triethylene glycol dialkyl ethers, tetraethylene glycol monoalkyl ethers, tetraethylene glycol dialkyl ethers, polyethylene glycol monoalkyl ethers, and polyethylene glycol dialkyl ethers are more preferred; ethylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, and ethylene glycol dibutyl ether; diethylene glycol dialkyl ethers such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, and diethylene glycol dibutyl ether; triethylene glycol dialkyl ethers such as triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dipropyl ether, and triethylene glycol dibutyl ether; tetraethylene glycol dialkyl ethers such as tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dipropyl ether, and tetraethylene glycol dibutyl ether; polyethylene glycol dialkyl ethers such as polyethylene glycol dimethyl ether, polyethylene glycol diethyl ether, polyethylene glycol dipropyl ether, and polyethylene glycol dibutyl ether is more preferred, Diethylene glycol dialkyl ethers are even more preferred, Diethylene glycol dimethyl ether is particularly preferred.

[0044] The epoxy compound may include, for example, monofunctional epoxy compounds and polyfunctional epoxy compounds.The monofunctional epoxy compound may include, for example, 1,2-epoxyethane, 1,2-epoxypropane, 1,2-epoxybutane, 1,2-epoxy-2-methylpropane, 1-phenyl-1,2-epoxyethane, epichlorohydrin, epibromohydrin, glycidyl methyl ether, allyl glycidyl ether, polyethylene oxide glycidyl ether, glycidyl amide, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, stearyl glycidyl ether, lauryl glycidyl ether, butoxy polyethylene glycol glycidyl ether, phenol polyethylene glycol glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, p-methylphenyl glycidyl ether, p-ethylphenyl glycidyl ether, p-sec-butylphenyl glycidyl ether, p-tert-butylphenyl glycidyl, glycidyl acrylate, and glycidyl methacrylate. Examples of polyfunctional epoxy compounds include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, phenol novolac type epoxy compounds, cresol novolac type epoxy compounds, polyphenol type epoxy compounds, alicyclic epoxy compounds, aliphatic glycidyl ether type epoxy compounds, glycidyl ester type epoxy compounds, glycidyl diamine type epoxy compounds, heterocyclic epoxy compounds, and alicyclic epoxy compounds having a molecular weight of 1,000 or less.

[0045] Examples of crown ether compounds include 18-crown-6, 15-crown-5, 12-crown-4, dibenzo-18-crown-6, dicyclohexano-18-crown-6, and dibenzo-24-crown-8.

[0046] The negative electrode material contains at least one low molecular weight ether compound, and may contain two or more low molecular weight ether compounds.

[0047] The content of the low molecular weight ether compound is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.3% by mass or more, still more preferably 0.5% by mass or more, particularly preferably 0.8% by mass or more, and most preferably 1.5% by mass or more, based on the total mass of the negative electrode material. A zinc battery equipped with a negative electrode having such a negative electrode material has excellent life performance, particularly excellent life performance in float charging applications. The content of the low molecular weight ether compound is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 6% by mass or less, still more preferably 4% by mass or less, particularly preferably 3.5% by mass or less, and most preferably 2.5% by mass or less, based on the total mass of the negative electrode material. A zinc battery equipped with a negative electrode having such a negative electrode material has excellent life performance, particularly excellent life performance in float charging applications. The content of the low molecular weight ether compound is preferably, for example, 0.01 to 10 mass%, 0.1 to 8 mass%, 0.3 to 6 mass%, 0.5 to 4 mass%, 0.8 to 3.5 mass%, 1.5 to 3.5 mass%, or 1.5 to 2.5 mass% based on the total mass of the negative electrode material.

[0048] <Additives> The negative electrode material may further contain an additive. Examples of the additives include a binder, a dispersant, and a conductive agent.

[0049] Examples of binders include polyvinyl alcohol, polytetrafluoroethylene, carboxymethyl cellulose, hydroxyethyl cellulose, polyethylene oxide, polyethylene, and polypropylene. The molecular weight of the binder is usually greater than 1000.

[0050] The negative electrode material may contain one or more types of binder.

[0051] When the negative electrode material contains a binder, the content of the binder is preferably 0.5 to 10 parts by mass, more preferably 1 to 8 parts by mass, and even more preferably 2 to 6 parts by mass, relative to 100 parts by mass of the negative electrode active material containing zinc. The content of the binder in the negative electrode material is the content of the binder in the negative electrode material after chemical formation. For example, the negative electrode can be removed from the zinc battery after chemical formation, dried, and then the content of the binder in the negative electrode material can be measured and confirmed.

[0052] The negative electrode material preferably contains at least polyvinyl alcohol (hereinafter also referred to as "PVA") as a binder. Zinc batteries equipped with a negative electrode having such a negative electrode material tend to have better life performance, adhesion between the negative electrode active materials themselves, and adhesion of the negative electrode material to the negative electrode current collector.

[0053] From the viewpoint of easily obtaining excellent life performance and sufficient adhesion, the saponification degree of PVA is preferably 60 to 99.9 mol%, more preferably 75 to 99.5 mol%, even more preferably 90 to 99.5 mol%, still more preferably 92 to 99.5 mol%, and particularly preferably 96 to 99 mol%. The saponification degree of PVA is measured by a method in accordance with JIS K6726:1994.

[0054] From the viewpoint of easily obtaining excellent life performance and sufficient adhesion, the average polymerization degree of the PVA is preferably 250 to 2400, more preferably 500 to 1800, and even more preferably 800 to 1300. The average polymerization degree of the PVA is measured by a method in accordance with JIS K6726:1994.

[0055] Hereinafter, the case where the negative electrode material contains PVA will be described. From the viewpoint of easily obtaining excellent life performance and sufficient adhesion, the content of PVA is preferably 0.1 mass % or more, more preferably 0.3 mass % or more, even more preferably 0.5 mass % or more, and particularly preferably 1 mass % or more, based on the total mass of the negative electrode material. From the viewpoint of ensuring excellent discharge characteristics, the content of PVA is preferably 10 mass % or less, more preferably 5 mass % or less, and even more preferably 3 mass % or less, based on the total mass of the negative electrode material. The content of PVA is preferably, for example, 0.1 to 10 mass %, 0.3 to 5 mass %, 0.5 to 3 mass %, or 1 to 3 mass % based on the total mass of the negative electrode material.

[0056] The negative electrode material may contain, as a binder, a binder other than PVA in addition to PVA. Examples of binders other than PVA include polytetrafluoroethylene, carboxymethyl cellulose, hydroxyethyl cellulose, polyethylene oxide, polyethylene, and polypropylene. Among these, polytetrafluoroethylene is preferred.

[0057] When the negative electrode material contains PVA and a binder other than PVA, the content of the binder other than PVA is preferably 10 to 1000 parts by mass, more preferably 50 to 700 parts by mass, and even more preferably 100 to 500 parts by mass relative to 100 parts by mass of PVA.

[0058] The dispersant improves the dispersibility of the negative electrode active material in the negative electrode material-forming composition, which will be described later. Examples of dispersants include polycarboxylic acids (carboxylic acid copolymers), polyacrylic acids, polyethers, and polymethylsiloxanes. However, the dispersants do not include the low-molecular-weight ether compounds mentioned above. When the negative electrode material contains a dispersant, the content of the dispersant is preferably 0.1 to 1 part by mass per 100 parts by mass of the zinc-containing negative electrode active material.

[0059] The conductive agent contributes to, for example, the effect of suppressing self-discharge or the effect of suppressing the decrease in the electrolyte solution. The conductive agent contains at least one metal selected from the group consisting of bismuth (Bi), indium (In), lead (Pb), cadmium (Cd), thallium (Tl), and tin (Sn). The conductive agent preferably contains at least one metal selected from the group consisting of bismuth and indium.

[0060] The conductive agent is preferably a metal oxide, more preferably a metal oxide containing the above metals, and even more preferably a metal oxide containing at least one selected from the group consisting of bismuth and indium. The negative electrode material preferably contains at least one selected from the group consisting of bismuth oxide and indium oxide.

[0061] When the negative electrode material contains a conductive agent, the content of the conductive agent is preferably 0.5 to 30 mass %, more preferably 1 to 20 mass %, and even more preferably 2 to 10 mass %, based on the total mass of the negative electrode material.

[0062] From the viewpoint of reducing the solubility of zinc oxide and making it easier to suppress morphological changes in the negative electrode, the negative electrode material may further contain at least one selected from the group consisting of metal halides such as potassium fluoride, alkali metal hydroxides such as lithium hydroxide, and carbonates such as potassium carbonate and sodium carbonate. When the negative electrode material contains a metal halide, the content of the metal halide may be, for example, 0.1 to 1 part by mass per 100 parts by mass of the zinc-containing negative electrode active material.

[0063] The negative electrode material may contain one or more additives.

[0064] <Method of manufacturing the negative electrode> The negative electrode can be produced, for example, using a negative electrode current collector and a negative electrode material-forming composition. The negative electrode material-forming composition can be produced, for example, by dissolving or dispersing a negative electrode active material containing zinc, a low-molecular-weight ether compound, and optional additives in a solvent or dispersion medium such as water. Specifically, the negative electrode can be produced by applying or filling a paste-like negative electrode material-forming composition onto a negative electrode current collector and then drying it. The negative electrode material forming composition may further contain water such as ion-exchanged water as a solvent or dispersion medium. The state of the negative electrode material forming composition is not particularly limited. In one embodiment, the negative electrode material forming composition may be in a paste form.

[0065] The water content (moisture content) in the negative electrode material-forming composition is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on the total mass of the negative electrode material-forming composition, and is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less. The moisture content is preferably, for example, 5 to 40% by mass, 10 to 35% by mass, or 15 to 30% by mass.

[0066] A liquid medium other than water (excluding compounds that fall under the category of low-molecular-weight ether compounds) may be added to the water in order to more uniformly disperse the zinc-containing negative electrode active material in the composition, more uniformly dissolve or disperse the binder, etc. Examples of the liquid medium other than water include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, and ethylene glycol.

[0067] [Zinc battery] The zinc battery of the present disclosure includes a positive electrode, a zinc battery negative electrode of the present disclosure, and an electrolyte. The zinc battery may further include a separator. The zinc battery may be in a pre-formed or post-formed state. Each component in the following description may be used alone or in combination of two or more.

[0068] In one embodiment, a zinc battery includes a battery case, an electrolyte, and an electrode group such as an electrode plate group. The electrode group includes a positive electrode, a negative electrode, and a separator. The electrolyte and the electrode group are contained in the battery case.

[0069] In one embodiment, the electrode group includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode. For example, one or more separators are disposed between adjacent positive electrodes and negative electrodes. The electrode group may include multiple positive electrodes, multiple negative electrodes, and multiple separators. When the electrode group includes multiple positive electrodes and / or multiple negative electrodes, the positive electrodes and negative electrodes may be stacked alternately with separators interposed between them. The multiple positive electrodes and the multiple negative electrodes may be connected to each other, for example, by straps.

[0070] Examples of zinc batteries include nickel-zinc batteries, such as nickel-zinc secondary batteries, in which the positive electrode is a nickel electrode; air-zinc batteries, such as air-zinc secondary batteries, in which the positive electrode is an air electrode; and silver-zinc batteries, such as silver-zinc secondary batteries, in which the positive electrode is a silver oxide electrode.

[0071] The zinc battery of the present disclosure has excellent life performance, particularly excellent life performance in float charging applications. Therefore, the zinc battery of the present disclosure is suitable as a battery for standby applications, such as an uninterruptible power supply (UPS), a backup power source for a server or elevator, a power source for a disaster prevention or security system, or a power source for emergency equipment.

[0072] The negative electrode for zinc batteries is as described above, and a description thereof will be omitted here.

[0073] <Positive electrode> Hereinafter, the zinc battery of the present disclosure will be described in detail using as an example a nickel-zinc battery in which the positive electrode is a nickel electrode, such as a nickel-zinc secondary battery. The positive electrode includes, for example, a positive electrode current collector and a positive electrode material supported on the positive electrode current collector. The positive electrode material may be disposed on at least one main surface of the positive electrode current collector, or may be disposed on both main surfaces of the positive electrode current collector. The positive electrode may be either before or after chemical formation.

[0074] The positive electrode current collector forms a conductive path for current from the positive electrode material. The positive electrode current collector may have a shape such as a flat plate or a sheet. The positive electrode current collector may be a collector with a three-dimensional mesh structure made of, for example, foamed metal, expanded metal, punched metal, or metal fiber felt.

[0075] The positive electrode current collector may be made of, for example, a material that is conductive and alkali-resistant. Examples of such materials include materials that are stable even at the reaction potential of the positive electrode. Examples of such materials include materials with a redox potential higher than the reaction potential of the positive electrode, and materials that form a protective film such as an oxide film on the substrate surface in an alkaline aqueous solution to stabilize the substrate. Furthermore, at the positive electrode, a decomposition reaction of the electrolyte may occur as a side reaction, generating oxygen gas. Materials with a high oxygen overvoltage are preferred because they can suppress the progression of such side reactions.

[0076] Specific examples of materials constituting the positive electrode current collector include platinum, nickel, and metal-plated metal materials. Examples of nickel include foamed nickel. For metal plating, for example, tin or nickel is used. Examples of metal materials include copper, brass, and steel. The metal plating may be applied to at least a portion of the surface of the metal material. Among these, a positive electrode current collector made of foamed nickel is preferred. From the viewpoint of further improving high-rate discharge performance, it is preferable that at least the portion of the positive electrode current collector that supports the positive electrode material (hereinafter also referred to as the "positive electrode material support portion") is made of foamed nickel.

[0077] The positive electrode material may be, for example, layered. That is, the positive electrode may have a positive electrode material layer. The positive electrode material layer may be formed on a positive electrode current collector. When the positive electrode material support part in the positive electrode current collector has a three-dimensional mesh structure, the positive electrode material may be filled between the meshes of the positive electrode material support part to form the positive electrode material layer.

[0078] The positive electrode material contains a positive electrode active material containing nickel. Examples of nickel-containing positive electrode active materials include nickel oxyhydroxide (NiOOH) and nickel hydroxide. In one embodiment, the positive electrode material contains nickel oxyhydroxide when the battery is in a fully charged state, and nickel hydroxide when the battery is in an end-of-discharge state. The content of the positive electrode active material is preferably 50 to 99 mass %, more preferably 50 to 95 mass %, based on the total mass of the positive electrode material.

[0079] The positive electrode material may further contain additives, such as a binder, a conductive agent, an expansion inhibitor, and a rare earth metal compound.

[0080] Examples of the binder include hydrophilic or hydrophobic polymers. Specific examples of the binder include carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, sodium polyacrylate, and fluorine-based polymers such as polytetrafluoroethylene. When the positive electrode material contains a binder, the content of the binder is preferably 0.01 to 5 parts by mass relative to 100 parts by mass of the positive electrode active material.

[0081] Examples of the conductive agent include cobalt compounds such as metallic cobalt, cobalt oxide, and cobalt hydroxide. When the positive electrode material contains a conductive agent, the content of the conductive agent is preferably 1 to 20 parts by mass per 100 parts by mass of the positive electrode active material.

[0082] An example of the expansion inhibitor is zinc oxide. When the positive electrode material contains an expansion inhibitor, the content of the expansion inhibitor is preferably 0.01 to 5 parts by mass relative to 100 parts by mass of the positive electrode active material.

[0083] An example of the rare earth metal compound is yttrium oxide. When the positive electrode material contains a rare earth metal compound, the content of the rare earth metal compound is preferably 0.01 to 5 parts by mass per 100 parts by mass of the positive electrode active material.

[0084] <Separator> Materials constituting the separator include, for example, organic materials, inorganic materials, and organic-inorganic materials. Examples of organic materials include resin materials such as polyolefins, polyamides, ion exchange resins, and cellophane-based recycled resins. Examples of polyolefins include polyethylene and polypropylene. Examples of inorganic materials include oxides such as alumina, titania, and silicon dioxide; nitrides such as aluminum nitride and silicon nitride; and sulfates such as barium sulfate and calcium sulfate. Examples of organic-inorganic materials include porous coordination polymers (PCP / MOF).

[0085] Specific examples of the separator include polyolefin-based porous membranes, polyamide-based porous membranes, ion-exchange resin membranes, cellophane-based recycled resin membranes, inorganic-organic hybrid separators, polyolefin-based nonwoven fabrics, and polyamide-based nonwoven fabrics.

[0086] The separator may have, for example, a flat plate or sheet shape. The separator may be, for example, in the form of a bag having an opening so that the positive electrode and / or the negative electrode can be housed therein. In this case, the positive electrode and / or the negative electrode may be housed in the bag-shaped separator.

[0087] The separator may contain a surfactant from the viewpoint of hydrophilization. Examples of surfactants include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. From the viewpoint of hydrophilization, the separator may be subjected to a surface treatment such as surfactant treatment, sulfonation treatment, fluorine gas treatment, acrylic acid graft polymerization treatment, corona discharge treatment, or plasma treatment. A hydrophilized separator is more compatible with the electrolyte and more likely to obtain a sufficient current density.

[0088] In one embodiment, the zinc battery of the present disclosure may have a first separator including a porous membrane and a second separator including a nonwoven fabric as separators. In the zinc battery of this embodiment, the first separator including at least a porous membrane and the second separator including at least a nonwoven fabric are disposed between the positive electrode and the negative electrode as separators.

[0089] The positional relationship between the first separator and the second separator is not particularly limited. The first separator may be disposed closer to the positive electrode than the second separator, and the second separator may be disposed closer to the positive electrode than the first separator. In other words, the second separator may be disposed closer to the negative electrode than the first separator, and the first separator may be disposed closer to the negative electrode than the second separator.

[0090] Two or more porous membranes and two or more nonwoven fabrics may be disposed between the positive electrode and the negative electrode. The zinc battery of the present disclosure may further include a third separator made of a material other than the porous membrane and the nonwoven fabric.

[0091] The term "porous membrane" as used herein refers to a porous membrane that electrically insulates the positive electrode and the negative electrode while being ion-permeable. The term "porous membrane" as used herein does not include nonwoven fabrics, which will be described in detail later. Porous membranes that satisfy conditions such as resistance to oxidation on the positive electrode side and reduction on the negative electrode side, and alkali resistance can be used. The porous membrane may have a shape such as a flat plate or a sheet, or may have a bag-like shape that can accommodate the positive electrode and / or the negative electrode.

[0092] Examples of materials constituting the porous membrane include the same materials as those exemplified as materials constituting the separator.Specific examples of the porous membrane include polyolefin-based porous membranes, polyamide-based porous membranes, ion-exchange resin membranes, cellophane-based recycled resin membranes, and inorganic-organic hybrid porous membranes.The porous membrane formed of an inorganic material may be, for example, a porous membrane containing particles of an inorganic material.

[0093] The porous membrane is preferably a microporous membrane, specifically, a porous membrane having the average pore size and / or air permeability described below.

[0094] From the viewpoint of achieving superior battery life performance, the average pore diameter of the porous membrane is preferably 20 to 250 nm, more preferably 30 to 200 nm, and even more preferably 40 to 150 nm. The average pore diameter of the porous membrane is measured with a mercury porosimeter (for example, manufactured by Micrometeritics, trade name: AutoPoreIV9510).

[0095] From the viewpoint of achieving superior battery life performance, the air permeability of the porous membrane is preferably 100 to 700 sec / 100 mL, more preferably 150 to 600 sec / 100 mL, and even more preferably 200 to 500 sec / 100 mL. The air permeability of the porous membrane is measured by a method in accordance with JIS P8117:2009.

[0096] The thickness of the porous membrane is preferably 5 to 100 μm, more preferably 10 to 75 μm, and even more preferably 15 to 50 μm, from the viewpoint of achieving superior battery life performance. The average thickness value can be used as the thickness of the porous membrane. Specifically, five porous membranes each measuring approximately 10 cm x 10 cm are prepared, and the thickness of each porous membrane is measured at any nine points, and the average thickness value can be used as the thickness of the porous membrane.

[0097] The porous membrane may contain a surfactant from the viewpoint of hydrophilization. Examples of surfactants include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. From the viewpoint of hydrophilization, the porous membrane may be subjected to surface treatment such as surfactant treatment, sulfonation treatment, fluorine gas treatment, acrylic acid graft polymerization treatment, corona discharge treatment, or plasma treatment. A hydrophilized porous membrane is easily compatible with an electrolyte and easily obtains a sufficient current density.

[0098] Examples of fibers that make up nonwoven fabrics include cellulose fibers, aramid fibers, nylon fibers, vinylon fibers, polyester fibers, rayon fibers, polyolefin fibers, and glass fibers. Examples of polyolefin fibers include polyethylene fibers and polypropylene fibers.

[0099] From the viewpoint of achieving superior battery life performance, the average pore diameter of the nonwoven fabric is preferably 0.5 to 50 μm, more preferably 1.0 to 40 μm, and even more preferably 2.0 to 30 μm. The method for measuring the average pore diameter of the nonwoven fabric is the same as the method for measuring the average pore diameter of the porous membrane described above.

[0100] From the viewpoint of achieving superior battery life performance, the air permeability of the nonwoven fabric is preferably 0.1 to 150 sec / 100 mL, more preferably 0.15 to 100 sec / 100 mL, and even more preferably 0.2 to 50 sec / 100 mL. The method for measuring the air permeability of the nonwoven fabric is the same as the method for measuring the air permeability of the porous membrane described above.

[0101] From the viewpoint of achieving superior battery life performance, the thickness of the nonwoven fabric is preferably 20 to 250 μm, more preferably 30 to 200 μm, and even more preferably 40 to 150 μm. The average thickness can be used as the thickness of the nonwoven fabric. The method for measuring the thickness of the nonwoven fabric is the same as the method for measuring the thickness of the porous membrane described above.

[0102] <Electrolyte> The electrolyte contains, for example, an alkali metal hydroxide and a liquid medium.

[0103] Examples of alkali metal hydroxides include potassium hydroxide (KOH), sodium hydroxide (NaOH), and lithium hydroxide (LiOH). The alkali metal hydroxides may be ionized (dissociated) in an aqueous solution or may exist as a salt. From the viewpoint of easily suppressing a decrease in discharge capacity during storage of a zinc battery and easily obtaining excellent high-rate discharge performance, the electrolyte preferably contains at least one selected from the group consisting of potassium hydroxide and lithium hydroxide, and more preferably contains at least potassium hydroxide.

[0104] The content of alkali metal hydroxide in the electrolyte is preferably 10 to 50 mass%, more preferably 15 to 45 mass%, even more preferably 20 to 40 mass%, still more preferably 25 to 35 mass%, and particularly preferably 30 to 35 mass%, based on the total mass of the electrolyte, from the viewpoint of easily suppressing a decrease in discharge capacity during storage of a zinc battery and easily obtaining excellent high-rate discharge performance.

[0105] When the electrolyte contains potassium hydroxide, the content of potassium hydroxide is preferably 10 to 50 mass%, more preferably 15 to 45 mass%, even more preferably 20 to 40 mass%, still more preferably 25 to 35 mass%, and particularly preferably 25 to 30 mass%, based on the total mass of the electrolyte, from the viewpoint of easily suppressing a decrease in discharge capacity during storage of the zinc battery and easily obtaining excellent high-rate discharge performance.

[0106] When the electrolyte contains lithium hydroxide, the content of lithium hydroxide is preferably 0.1 to 3 mass%, more preferably 0.3 to 2 mass%, even more preferably 0.5 to 1.5 mass%, still more preferably 0.8 to 1.2 mass%, and particularly preferably 1 to 1.2 mass%, based on the total mass of the electrolyte, from the viewpoint of easily suppressing a decrease in discharge capacity during storage of the zinc battery and easily obtaining excellent high-rate discharge performance.

[0107] An example of the liquid medium is water such as ion-exchanged water. The content of the liquid medium in the electrolytic solution is preferably 50 to 90 mass %, more preferably 55 to 85 mass %, and even more preferably 60 to 80 mass %, based on the total mass of the electrolytic solution.

[0108] The electrolyte may further contain a surfactant. Examples of surfactants include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. Specific examples of surfactants include didodecyldimethylammonium bromide, tetradecyltrimethylammonium bromide, polyoxyethylene decyl ether, and polyoxyalkylene alkyl ether phosphate esters. Among these, tetradecyltrimethylammonium bromide is preferred from the viewpoints of easily achieving excellent battery life performance and easily suppressing a decrease in discharge capacity.

[0109] When the electrolytic solution contains a surfactant, the content of the surfactant is preferably 0.001 to 5 mass%, more preferably 0.003 to 2.5 mass%, even more preferably 0.005 to 1 mass%, and particularly preferably 0.01 to 0.5 mass%, based on the total mass of the electrolytic solution, from the viewpoint of easily obtaining excellent battery life performance and easily suppressing a decrease in the discharge capacity of the zinc battery.

[0110] The electrolyte may further contain a carbohydrate. Examples of carbohydrates include monosaccharides, disaccharides, trisaccharides, and polysaccharides (excluding sugars that fall into the disaccharide or trisaccharide category). Examples of monosaccharides include glucose, fructose, galactose, arabinose, ribose, mannose, xylose, sorbose, rhamnose, fucose, and ribonucleotides, as well as hydrates thereof. Examples of disaccharides include sucrose, maltose, trehalose, cellobiose, gentiobiose, lactose, and melibiose, as well as hydrates thereof. Examples of trisaccharides include kestose, melezitose, gentianose, raffinose, and melezitose, as well as hydrates thereof. Examples of polysaccharides include cyclodextrins (e.g., γ-cyclodextrin), fungitetraose, and stachyose.

[0111] When the electrolyte solution contains carbohydrates, the carbohydrate content is preferably 0.1 to 5 mass%, more preferably 0.3 to 4.5 mass%, even more preferably 0.5 to 4 mass%, even more preferably 0.8 to 3.5 mass%, and particularly preferably 1 to 3 mass%, based on the total mass of the electrolyte solution, from the viewpoint of easily suppressing the decrease in discharge capacity when the zinc battery is stored and easily obtaining excellent high-rate discharge performance.

[0112] The electrolyte may further contain at least one selected from the group consisting of potassium phosphate, potassium fluoride, potassium carbonate, sodium phosphate, sodium fluoride, zinc oxide, antimony oxide, and titanium dioxide.

[0113] <Zinc battery manufacturing method> Hereinafter, a method for manufacturing a nickel-zinc battery will be described as an example of a method for manufacturing a zinc battery according to the present disclosure. However, the method for manufacturing a nickel-zinc battery is not limited to the following description.

[0114] A method for producing a nickel-zinc battery includes, for example, a step (1) of preparing components of a zinc battery and a step (2) of obtaining a nickel-zinc battery using the components.

[0115] In step (1), at least a positive electrode and a negative electrode are prepared as components of a zinc battery. In addition to the positive electrode and the negative electrode, the components of a zinc battery include, for example, a separator and an electrolyte.

[0116] The negative electrode can be obtained, for example, by forming a negative electrode material layer using the above-mentioned negative electrode material-forming composition. Specifically, the negative electrode can be obtained by applying or filling the negative electrode material-forming composition onto a negative electrode current collector to form a negative electrode material layer. The negative electrode material-forming composition is, for example, in a paste form. The positive electrode can be obtained, for example, by adding a liquid medium such as water to a raw material of the positive electrode material and kneading them to obtain a positive electrode material paste, and then forming a positive electrode material layer using the positive electrode material paste. Specifically, the positive electrode can be obtained by applying or filling the positive electrode material paste onto a positive electrode current collector to form a positive electrode material layer.

[0117] Examples of methods for forming electrode material layers such as a positive electrode layer and a negative electrode layer include a method in which an electrode material paste is applied to or filled into a current collector and then dried. If necessary, the density of the electrode material layer may be increased by pressing with a roller or the like.

[0118] In step (2), for example, the positive and negative electrodes obtained in step (1) are alternately stacked with separators interposed therebetween, and then the positive and negative electrodes are connected with straps to form an electrode group. Next, this electrode group is placed in a battery case, and a lid is attached to the top of the battery case to obtain an unformed zinc battery (nickel-zinc battery).

[0119] The following describes a case where a first separator including a porous membrane and a second separator including a nonwoven fabric are used as separators. In preparing an electrode assembly, methods for disposing a separator between a positive electrode and a negative electrode include, for example, a method in which a porous membrane and a nonwoven fabric are first stacked to prepare a laminate, and then the laminate is disposed between the positive electrode and the negative electrode; and a method in which a porous membrane and a nonwoven fabric are disposed separately between the positive electrode and the negative electrode. The separator may be disposed between the positive electrode and the negative electrode by accommodating a positive electrode in a porous membrane processed into a bag shape, accommodating a negative electrode in a porous membrane processed into a bag shape, and disposing a nonwoven fabric between the bag containing the positive electrode and the bag containing the negative electrode.

[0120] Next, the electrolyte is poured into the battery case of the unformed zinc battery and left for a certain period of time. Then, charging is performed under predetermined conditions, and the zinc battery (nickel-zinc battery) is obtained by forming the battery. The forming conditions can be adjusted depending on the properties of the positive and negative electrode active materials.

[0121] <Other zinc batteries> The zinc battery of the present disclosure may be, for example, an air-zinc battery in which the positive electrode is an air electrode, such as an air-zinc secondary battery, or a silver-zinc battery in which the positive electrode is a silver oxide electrode, such as a silver-zinc secondary battery.

[0122] The air electrode of the air-zinc battery can be, for example, a known air electrode used in air-zinc batteries, and includes, for example, at least one material selected from the group consisting of an air electrode catalyst and an electron conductive material.

[0123] Examples of the air electrode catalyst include materials that function as the positive electrode in air-zinc batteries. Various air electrode catalysts that can utilize oxygen as the positive electrode active material can be used. Specific examples of the air electrode catalyst include carbon-based materials with redox catalytic properties, such as graphite; metal materials with redox catalytic properties, such as platinum and nickel; and inorganic oxide materials with redox catalytic properties, such as perovskite oxides, manganese dioxide, nickel oxide, cobalt oxide, and spinel oxide. Examples of the air electrode catalyst that can also function as an electron conductive material may also be used.

[0124] The air electrode catalyst may be, for example, in the form of particles or other shapes. The content of the air electrode catalyst in the air electrode is preferably 5 to 70 volume %, more preferably 5 to 60 volume %, and even more preferably 5 to 50 volume %, based on the total volume of the air electrode.

[0125] Examples of the electron-conductive material include materials that are electrically conductive and allow electron conduction between the air electrode catalyst and the separator. Specific examples of the electron-conductive material 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 fiber and metal fiber; metal powders such as copper, silver, nickel, and aluminum; and organic electron-conductive materials such as polyphenylene derivatives.

[0126] The electron conductive material may be in the form of particles or other shapes, and the content of the electron conductive material in the air electrode is preferably 10 to 80% by volume, more preferably 15 to 80% by volume, and even more preferably 20 to 80% by volume, based on the total volume of the air electrode.

[0127] The electronically conductive material is preferably used in a form that provides a continuous phase in the thickness direction of the air electrode. The electronically conductive material may be, for example, a porous material. The electronically conductive material may be, for example, in the form of a mixture or composite with an air electrode catalyst. For example, the electronically conductive material may also function as an air electrode catalyst.

[0128] The silver oxide electrode of the silver-zinc battery may be, for example, a known silver oxide electrode used in silver-zinc batteries, and may contain, for example, silver(I) oxide.

[0129] [Example of situation] The present disclosure relates to, for example, the following [1] to [5]. [1] A negative electrode for a zinc battery having a negative electrode current collector and a negative electrode material supported on the negative electrode current collector, wherein the negative electrode material contains a negative electrode active material containing zinc and a low molecular weight organic compound having an ether bond. [2] The negative electrode for a zinc battery according to [1], wherein the low molecular weight organic compound comprises at least one selected from the group consisting of carbohydrates and glycol ether compounds. [3] The zinc battery negative electrode according to [1] or [2], wherein the low molecular weight organic compound comprises at least one selected from the group consisting of monosaccharides, disaccharides, trisaccharides, alkylene glycol monoalkyl ethers, alkylene glycol dialkyl ethers, dialkylene glycols, dialkylene glycol monoalkyl ethers, dialkylene glycol dialkyl ethers, trialkylene glycols, trialkylene glycol monoalkyl ethers, trialkylene glycol dialkyl ethers, tetraalkylene glycols, tetraalkylene glycol monoalkyl ethers, tetraalkylene glycol dialkyl ethers, polyalkylene glycols, polyalkylene glycol monoalkyl ethers, and polyalkylene glycol dialkyl ethers. [4] The negative electrode for a zinc battery according to any one of [1] to [3], wherein the content of the low molecular weight organic compound is 0.01 to 10 mass % based on the total mass of the negative electrode material. [5] A zinc battery comprising a positive electrode, the zinc battery negative electrode according to any one of [1] to [4] above, and an electrolyte solution. [Example]

[0130] The present disclosure will be specifically described below using examples, although the present disclosure is not limited to the following examples.

[0131] [Electrode material] The negative electrode materials used in the examples and comparative examples are listed below. Zinc oxide General product manufactured by Mitsui Mining & Smelting Co., Ltd. Metallic zinc MA-ZB (product name), manufactured by Mitsui Mining & Smelting Co., Ltd. Bismuth oxide Corefront Co., Ltd., 4115CB (product name) ·glucose Fujifilm Wako Pure Chemical Corporation, special grade reagent ·sucrose Fujifilm Wako Pure Chemical Corporation, special grade reagent Diethylene glycol dimethyl ether (diglyme) Fujifilm Wako Pure Chemical Industries, Ltd., Wako First Class Polytetrafluoroethylene PTFE D-210C (product name), manufactured by Daikin Industries, Ltd. Polyvinyl alcohol Saponification degree: 99 mol%, Kuraray Co., Ltd., Poval 60-98 (trade name)

[0132] The positive electrode materials used in the examples and comparative examples are listed below. Cobalt-coated nickel hydroxide powder Made by Gold Shine Energy Material Co.,Ltd. Y6 (product name) Cobalt metal EXTRA FINE (product name), manufactured by Nikkoshi Co., Ltd. Cobalt hydroxide Manufactured by Ise Chemical Industry Co., Ltd. Yttrium oxide Fujifilm Wako Pure Chemical Corporation, special grade reagent Carboxymethylcellulose Manufactured by Weiyi Chemical (Suzhou) Co., Ltd., BH90-3 (product name) Polytetrafluoroethylene PTFE D-210C (product name), manufactured by Daikin Industries, Ltd.

[0133] [Example 1] <Preparation of negative electrode> A tin-plated punched steel sheet with a 50% porosity was prepared as the negative electrode current collector. Next, predetermined amounts of zinc oxide, metallic zinc, bismuth oxide, glucose, polytetrafluoroethylene, polyvinyl alcohol, and ion-exchanged water were mixed together to prepare a negative electrode material paste. The mass ratio of the solid components other than the ion-exchanged water was adjusted to zinc oxide: metallic zinc: bismuth oxide: glucose: polytetrafluoroethylene: polyvinyl alcohol = 69.6:23.3:2.5:0.5:3.0:1.1, and the water content of the negative electrode material paste was adjusted to 20 mass% based on the total mass of the negative electrode material paste. The negative electrode material paste was then applied to the negative electrode current collector and dried at 80°C for 30 minutes to form a negative electrode material (negative electrode material layer) on the negative electrode current collector. Next, the negative electrode current collector after the application and drying of the negative electrode material paste was pressure-molded using a roll press to obtain an unformed negative electrode having a negative electrode material (negative electrode material layer).

[0134] <Preparation of positive electrode> A grid made of foamed nickel with a porosity of 95% was prepared. The grid was pressure-molded to obtain a positive electrode current collector. Next, a cathode material paste was prepared by kneading predetermined amounts of cobalt-coated nickel hydroxide powder, metallic cobalt, cobalt hydroxide, yttrium oxide, carboxymethyl cellulose, polytetrafluoroethylene, and ion-exchanged water. The mass ratio of the solid components other than the ion-exchanged water was adjusted to "nickel hydroxide: metallic cobalt: cobalt hydroxide: yttrium oxide: carboxymethyl cellulose: polytetrafluoroethylene = 88.0:10.3:0.3:1.0:0.3:0.1," and the moisture content of the cathode material paste was adjusted to 27.5 mass% based on the total mass of the cathode material paste. Next, the cathode material paste was applied to the cathode material support portion of the positive electrode current collector and then dried at 80°C for 30 minutes to form a cathode material (cathode material layer) on the cathode material support portion. Next, the positive electrode current collector after the application and drying of the positive electrode material paste was pressure-molded using a roll press to obtain an unformed positive electrode having a positive electrode material (positive electrode material layer).

[0135] <Preparing the separator> As the separator, a first separator and a second separator were used. A porous membrane (manufactured by Ube Industries, Ltd., trade name: UP3355, air permeability: 440 sec / 100 mL, average pore diameter: 80 nm, thickness: 25 μm) was used as the first separator. The porous membrane was hydrophilized using a surfactant, Triton-X100 (manufactured by Sigma-Aldrich Japan, LLC, trade name), before assembling the battery. Specifically, the hydrophilization treatment was performed by immersing the porous membrane in an aqueous solution containing 1 mass % of Triton-X100 for 24 hours, then removing the porous membrane from the aqueous solution and drying it at room temperature (25°C) for 1 hour. The air permeability of the porous membrane indicates the value after the hydrophilization treatment. The porous membrane was cut to a predetermined size, folded in half, and the folded part was used as the bottom, and the sides were heat-sealed to obtain a bag made of the porous membrane. As the second separator, a nonwoven fabric (manufactured by Nippon Kodoshi Kogyo Co., Ltd., product name: VL-100, air permeability: 0.3 sec / 100 mL, average pore diameter: 9.3 μm, thickness: 100 μm) was used. The nonwoven fabric was cut to a predetermined size before use. The air permeability is a value measured by a method conforming to JIS P8117:2009.

[0136] <Preparation of electrolyte> An electrolyte solution was prepared by mixing potassium hydroxide (KOH), lithium hydroxide (LiOH), tetradecyltrimethylammonium bromide, and ion-exchanged water so that the content ratio of each component relative to the total mass of the electrolyte solution was as follows: Potassium hydroxide: 30.0% by mass Lithium hydroxide: 1.0% by mass Tetradecyltrimethylammonium bromide: 0.1% by mass Ion-exchanged water: 68.9% by mass

[0137] <Preparing a Nickel-Zinc Battery> One unformed positive electrode was placed in a bag made of a porous membrane (first separator). Another unformed negative electrode was placed in another bag made of a porous membrane (first separator). The positive electrode, which was placed in a bag made of a porous membrane, the negative electrode, which was also placed in a bag made of a porous membrane, and a nonwoven fabric (second separator) were stacked, and then electrode plates of the same polarity were connected with straps to form an electrode assembly (electrode plate assembly). The electrode assembly consisted of two positive electrodes and three negative electrodes, with one nonwoven fabric placed between each positive and negative electrode (between the porous membrane on the positive electrode side and the porous membrane on the negative electrode side). This electrode assembly was then placed in a battery container, a lid was attached to the top of the container, and the above-mentioned electrolyte was poured into the container to obtain an unformed nickel-zinc battery. The battery was then charged at an ambient temperature of 25°C, 32 mA, and 12 hours to produce a nickel-zinc battery with a nominal capacity of 320 mAh.

[0138] [Examples 2 to 12 and Comparative Example 1] In the preparation of the negative electrode, the type of low molecular weight ether compound or the content ratio in the negative electrode material was changed as shown in Table 1. The negative electrode material paste, negative electrode, and nickel-zinc battery were prepared or fabricated in the same manner as in Example 1. The content ratio of the low molecular weight ether compound was adjusted by the amount of metal zinc added. In Comparative Example 1, no low molecular weight ether compound was added to the negative electrode material paste.

[0139] Comparative Example 2 <Preparation of negative electrode> A tin-plated punched steel sheet with a porosity of 50% was prepared as the negative electrode current collector. Next, predetermined amounts of zinc oxide, metallic zinc, bismuth oxide, polytetrafluoroethylene, polyvinyl alcohol, and ion-exchanged water were mixed together to prepare a negative electrode material paste. The mass ratio of the solid components other than the ion-exchanged water was adjusted to zinc oxide: metallic zinc: bismuth oxide: polytetrafluoroethylene: polyvinyl alcohol = 69.6:23.8:2.5:3.0:1.1, and the moisture content of the negative electrode material paste was adjusted to 20 mass% based on the total mass of the negative electrode material paste. The negative electrode material paste was then applied to the negative electrode current collector and dried at 80°C for 30 minutes to form a negative electrode material (negative electrode material layer) on the negative electrode current collector. The negative electrode current collector after application and drying of the negative electrode material paste was then pressure-molded using a roll press to obtain an unformed negative electrode having a negative electrode material (negative electrode material layer).

[0140] <Preparation of electrolyte> An electrolyte solution was prepared by mixing potassium hydroxide (KOH), lithium hydroxide (LiOH), tetradecyltrimethylammonium bromide, glucose, and ion-exchanged water so that the content ratio of each component relative to the total mass of the electrolyte solution was as follows: Potassium hydroxide: 30.0% by mass Lithium hydroxide: 1.0% by mass Tetradecyltrimethylammonium bromide: 0.1% by mass Glucose: 0.5% by mass Ion-exchanged water: 68.4% by mass

[0141] A nickel-zinc battery of Comparative Example 2 was fabricated in the same manner as in Example 1, except that the above negative electrode and the above electrolyte solution were used.

[0142] [Evaluation of float life performance] The nickel-zinc batteries of the Examples and Comparative Examples were evaluated for float life performance. The specific evaluation methods are shown below, and the results are shown in Table 1.

[0143] At an ambient temperature of 25°C, the nickel-zinc battery was charged at a constant voltage of 1.88V at 105.7mA (0.33C) until the current value decayed to 16mA (0.05C). It was then discharged at a constant current of 105.7mA (0.33C) until the battery voltage reached 1.1V. The discharge capacity at this time was taken as 100%. The nickel-zinc battery was then charged at a constant voltage of 1.84V for one month (30 days), after which it was discharged at a constant current of 105.7mA (0.33C) until the battery voltage reached 1.1V. The number of months until the discharge capacity had dropped to 60% was taken as the float life.

[0144] The "C" above is a relative expression of the magnitude of the current when discharging the rated capacity at a constant current from a fully charged state. The "C" above means "discharge current value (A) / battery capacity (Ah)." For example, the current that can discharge the rated capacity in 1 hour is defined as "1C," and the current that can discharge the rated capacity in 2 hours is defined as "0.5C."

[0145] [Table 1]

Claims

1. a negative electrode current collector; a negative electrode material supported on the negative electrode current collector; A zinc battery negative electrode having The negative electrode material is a negative electrode active material containing zinc; a low molecular weight organic compound having an ether bond; containing Anode for zinc batteries.

2. 2. The zinc battery negative electrode according to claim 1, wherein the low molecular weight organic compound comprises at least one selected from the group consisting of carbohydrates and glycol ether compounds.

3. The low molecular weight organic compound is Monosaccharides, disaccharides, trisaccharides, alkylene glycol monoalkyl ether, alkylene glycol dialkyl ether, dialkylene glycol, dialkylene glycol monoalkyl ether, dialkylene glycol dialkyl ether, Trialkylene glycol, trialkylene glycol monoalkyl ether, trialkylene glycol dialkyl ether, tetraalkylene glycol, tetraalkylene glycol monoalkyl ether, tetraalkylene glycol dialkyl ether, polyalkylene glycol, polyalkylene glycol monoalkyl ether, and Polyalkylene glycol dialkyl ether At least one selected from the group consisting of The negative electrode for a zinc battery according to claim 1 .

4. The zinc battery negative electrode according to claim 1, wherein the content of the low molecular weight organic compound is 0.01 to 10 mass% based on the total mass of the negative electrode material.

5. A positive electrode and The zinc battery negative electrode according to any one of claims 1 to 4, An electrolyte; A zinc battery comprising:

Images