Zinc batteries

Abstract

The present invention provides a zinc battery, comprising a positive electrode, a negative electrode, an electrolyte, and a spacer. In the zinc battery, the negative electrode has a negative electrode current collector and a negative electrode material supported by the negative electrode current collector. The negative electrode material contains a negative electrode active material including zinc and polyvinyl alcohol. The spacer has a first spacer comprising a porous membrane and a second spacer comprising a non-woven fabric.

Description

Technical Field

[0001] This invention relates to a zinc battery. Prior Technology

[0002] As zinc batteries, nickel-zinc batteries, air-zinc batteries, and silver-zinc batteries are known. For example, nickel-zinc batteries are known to be aqueous batteries that use aqueous electrolytes such as potassium hydroxide solution, thus possessing high safety. Furthermore, due to the combination of zinc and nickel electrodes, they exhibit a high electromotive force as aqueous batteries. In addition to their excellent input / output performance, nickel-zinc batteries are also low-cost, therefore their potential applications in industrial applications (such as backup power supplies) and automotive applications (such as hybrid vehicles) are being investigated.

[0003] From the perspective of the formation of the negative electrode material layer, in addition to using a negative electrode active material containing zinc, zinc batteries sometimes use cellulose-based compounds such as carboxymethyl cellulose as water-soluble polymer materials (for example, see Patent Document 1). [Existing Technical Documents] [Patent Literature]

[0004] Patent Document 1: Japanese Patent Application Publication No. 2019-160793 Summary of the Invention

[0005] [The problem that the invention aims to solve] For zinc batteries such as nickel-zinc batteries, there is a demand for further improvements in lifespan performance. However, in the zinc battery using cellulose-based compounds described in Patent Document 1, there are challenges in further improving lifespan performance and further reducing DC resistance.

[0006] One objective of this invention is to provide a zinc battery that can achieve excellent life performance in zinc batteries and also reduce DC resistance. [Methods for solving problems]

[0007] One aspect of the present invention provides the following zinc battery. [1] A zinc battery includes a positive electrode, a negative electrode, an electrolyte, and a spacer, wherein the negative electrode has a negative electrode current collector and a negative electrode material supported by the negative electrode current collector, the negative electrode material contains a negative electrode active material containing zinc and polyvinyl alcohol, and the spacer has a first spacer containing a porous membrane and a second spacer containing a nonwoven fabric. [2] The zinc battery as described in [1], wherein the negative electrode material contains a metal oxide comprising at least one selected from the group consisting of bismuth and indium. [3] A zinc battery as described in [1] or [2], wherein the negative electrode current collector comprises at least a portion of a tin-plated metal material on its surface. [4] The zinc battery as described in any one of [1] to [3], wherein the electrolyte contains an alkali metal hydroxide. [5] The zinc battery as described in any one of [1] to [4], wherein the electrolyte contains a surfactant. [6] The zinc battery as described in any one of [1] to [5], wherein the electrolyte contains sugar.

[0008] According to the zinc battery described above, excellent life performance can be obtained, and DC resistance can also be reduced. [The effects of the invention]

[0009] According to one aspect of the present invention, a zinc battery that can achieve excellent life performance in a zinc battery and also reduce DC resistance can be provided. Simple Explanation of the Diagram

[0010] none Implementation

[0011] In this specification, the numerical range indicated by "~" represents the range of minimum and maximum values ​​recorded before and after "~". Within the numerical ranges described in stages in this specification, the upper or lower limit of a certain stage's numerical range can be arbitrarily combined with the upper or lower limits of other stages' numerical ranges. Within the numerical ranges described in this specification, the upper or lower limit of that range can be replaced by the values ​​shown in the experimental examples. The term "A or B" can include either A or B, or both. Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more. In this specification, the amount of each component used in the composition, when multiple substances equivalent to each component are present in the composition, refers to the total amount of those substances present in the composition, unless otherwise specified. In this specification, the term "membrane" or "layer," when viewed in a planar view, includes not only the structure of the shape formed over the entire surface but also the structure of the shape formed in a portion. In this specification, the term "step" includes not only independent steps, but also steps that cannot be clearly distinguished from other steps, as long as the desired effect of the step is achieved.

[0012] The embodiments of the present invention will now be described in detail. However, the present invention is not limited to these embodiments and can be implemented in various ways within the scope of its spirit.

[0013] The zinc battery of this embodiment includes at least a positive electrode, a negative electrode, an electrolyte, and a spacer. In this zinc battery, the negative electrode has a negative electrode current collector and a negative electrode material supported by the negative electrode current collector. The negative electrode material contains a negative electrode active material including zinc and polyvinyl alcohol. The spacer has a first spacer comprising a porous membrane and a second spacer comprising a non-woven fabric.

[0014] The zinc battery of this embodiment exhibits excellent cycle life performance and reduced DC resistance. The main reasons for achieving this effect include, for example, the following main reasons, but are not limited to these main reasons.

[0015] First, it is known that in previous zinc batteries, the zinc dissolution reaction proceeds unevenly during charging and discharging, resulting in negative electrode degradation such as shape changes or internal short circuits, and thus reduced lifespan performance. However, the zinc battery of this embodiment contains polyvinyl alcohol in the negative electrode material. Therefore, it is speculated that the contact between active materials or between active materials and current collector is improved by polyvinyl alcohol, and excellent lifespan performance can be obtained by homogenizing the zinc dissolution reaction.

[0016] In addition, as mentioned above, in previous zinc batteries, zinc dissolution occurs during charging and discharging. This zinc dissolution occurs by the following: zinc hydroxide (Zn(OH)₂) generated at the negative electrode due to zinc dissolution dissolves in the electrolyte, thereby causing tetrahydroxyzincate ions ([Zn(OH)₄]²⁻) to diffuse into the electrolyte. However, in the zinc battery of this embodiment, the diffusion of tetrahydroxyzincate ions is suppressed by including a first spacer containing a porous membrane in the spacer. It is speculated that zinc deposition at the negative electrode is suppressed, resulting in superior lifespan performance. Furthermore, in this zinc battery, not only is the first spacer containing a porous membrane used as a spacer, but a second spacer containing nonwoven fabric is also used as a spacer, thereby retaining more electrolyte. Therefore, it is believed that the zinc battery of this embodiment not only has excellent lifespan performance but also excellent performance in reducing DC resistance.

[0017] Examples of zinc batteries include: nickel-zinc batteries with nickel as the positive electrode (e.g., nickel-zinc secondary batteries); air-zinc batteries with air as the positive electrode (e.g., air-zinc secondary batteries); and silver-zinc batteries with silver oxide as the positive electrode (e.g., silver-zinc secondary batteries).

[0018] The following uses a nickel-zinc battery as an example to explain the details of the zinc battery in this embodiment.

[0019] The zinc battery of this embodiment includes at least a positive electrode, a negative electrode (zinc electrode), and a spacer. The zinc battery may include, for example, an electrolytic cell, an electrolyte, and an electrode assembly (e.g., an electrode plate assembly) including the positive electrode, negative electrode, and spacer. The electrolyte and electrode assembly are housed within the electrolytic cell. The zinc battery can be either pre-chemically converted or post-chemically converted.

[0020] In an electrode group, a positive electrode (e.g., a positive plate) and a negative electrode (e.g., a negative plate) are adjacent to each other separated by one or more spacers. That is, one or more spacers are provided between adjacent positive and negative electrodes. An electrode group may include multiple positive electrodes, multiple negative electrodes, and spacers. When an electrode group includes multiple positive electrodes and / or multiple negative electrodes, the positive and negative electrodes may be alternately laminated separated by spacers. Multiple positive electrodes and multiple negative electrodes may be connected to each other, for example, by bonding plates.

[0021] In the zinc battery of this embodiment, the negative electrode includes a negative electrode current collector and a negative electrode material supported by the negative electrode current collector. The negative electrode material contains a negative electrode active material including zinc and polyvinyl alcohol. The negative electrode can be either before or after chemical conversion.

[0022] The negative electrode current collector forms a conductive path for the current from the negative electrode material. The negative electrode current collector can be, for example, flat or sheet-like. It can be a current collector with a three-dimensional mesh structure composed of foamed metal, expanded metal, punching metal, or a felt-like material of metal fibers. The negative electrode current collector can also contain materials that are conductive and alkali-resistant. Such materials can be, for example, materials that are stable even at the reaction potential of the negative electrode (materials with a redox potential higher than the reaction potential of the negative electrode, materials stabilized by forming a protective film on the substrate surface in an alkaline aqueous solution, etc.). Furthermore, although hydrogen gas is generated by the decomposition reaction of the electrolyte as a side reaction at the negative electrode, materials with high hydrogen overvoltage are preferred in terms of suppressing this side reaction. Specific examples of materials constituting the negative electrode current collector include metal materials (copper, brass, steel, nickel, etc.) whose surface is at least partially coated with metals such as zinc, lead, or tin.

[0023] The negative electrode material can be formed into a layer, for example. That is, the negative electrode can have a negative electrode material layer. The negative electrode material layer can be formed on the negative electrode current collector. When the portion of the negative electrode current collector supporting the negative electrode material has a three-dimensional mesh structure, the negative electrode material can be filled between the meshes of the current collector to form the negative electrode material layer.

[0024] The negative electrode material contains a negative electrode active material (electrode active material) including zinc. Examples of negative electrode active materials include metallic zinc, zinc oxide, and zinc hydroxide. The negative electrode active material may contain only one of these components or multiple components. For example, the negative electrode material contains metallic zinc in a fully charged state and zinc oxide and zinc hydroxide in a discharged state. The negative electrode active material may be in particulate form. That is, the negative electrode material may also contain at least one component selected from the group consisting of metallic zinc particles, zinc oxide particles, and zinc hydroxide particles.

[0025] The content of the negative electrode active material, based on the total mass of the negative electrode material, is preferably within the following range. From the viewpoint of easily balancing excellent cycle life performance and excellent high-efficiency discharge performance, the content of the negative electrode active material is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 75% by mass or more. From the viewpoint of easily balancing excellent cycle life performance and excellent high-efficiency discharge performance, the content of the negative electrode active material is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. From these perspectives, the content of the negative electrode active material is preferably 50% by mass to 95% by mass.

[0026] The negative electrode material contains at least polyvinyl alcohol (hereinafter sometimes simply referred to as PVA) as a binder. From the viewpoint of easily obtaining excellent lifespan performance and sufficient adhesion of the negative electrode material to the current collector, the degree of saponification of the polyvinyl alcohol is preferably 60 mol% or more, 75 mol% or more, 90 mol% or more, 92 mol% or more, or 96 mol% or more. From the viewpoint of easily obtaining excellent lifespan performance and sufficient adhesion of the negative electrode material to the current collector, the degree of saponification of the polyvinyl alcohol is preferably 99.9 mol% or less, more preferably 99 mol% or less. In view of these points, the preferred saponification degree of polyvinyl alcohol is 60 mol%~99.9 mol%, 60 mol%~99 mol%, 75 mol%~99.9 mol%, 75 mol%~99 mol%, 90 mol%~99.9 mol%, 90 mol%~99 mol%, 92 mol%~99.9 mol%, 92 mol%~99 mol%, 96 mol%~99.9 mol%, or 96 mol%~99 mol%. Furthermore, the saponification degree of polyvinyl alcohol described herein is a value obtained by measurement according to the method of Japanese Industrial Standards (JIS) K 6726:1994.

[0027] From the viewpoint of easily obtaining excellent lifespan performance and sufficient adhesion of the negative electrode material to the current collector, the average degree of polymerization of polyvinyl alcohol is preferably 250 or higher, more preferably 500 or higher, and even more preferably 800 or higher. From the viewpoint of easily obtaining excellent lifespan performance and sufficient adhesion of the negative electrode material to the current collector, it is preferably 2400 or lower, more preferably 1800 or lower, and even more preferably 1300 or lower. From these viewpoints, the average degree of polymerization of polyvinyl alcohol is preferably 250 to 2400. Furthermore, the average degree of polymerization mentioned here is a value obtained by measuring according to the method in JIS K 6726:1994.

[0028] From the perspective of easily obtaining excellent lifespan performance and sufficient adhesion of the negative electrode material to the current collector, and from the perspective of further reducing DC resistance, the polyvinyl alcohol content, based on the total mass of the negative electrode material, is preferably 0.1% by mass or more, 0.3% by mass or more, 0.5% by mass or more, or 1% by mass or more. From the perspective of ensuring excellent discharge characteristics, the polyvinyl alcohol content, based on the total mass of the negative electrode material, is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. Regarding these viewpoints, the polyvinyl alcohol (PVA) content is based on the total mass of the negative electrode material, preferably 0.1%~10% by mass, 0.1%~5% by mass, 0.1%~3% by mass, 0.3%~10% by mass, 0.3%~5% by mass, 0.3%~3% by mass, 0.5%~10% by mass, 0.5%~5% by mass, 0.5%~3% by mass, 1%~10% by mass, 1%~5% by mass, or 1%~3% by mass. Furthermore, the PVA content refers to the content in the chemically converted negative electrode material. For example, it can be confirmed by removing the negative electrode from a chemically converted zinc battery, drying it, and then measuring the PVA content in the negative electrode material.

[0029] The negative electrode material may contain binders other than polyvinyl alcohol. Examples of binders include polytetrafluoroethylene, hydroxyethyl cellulose, polyethylene oxide, polyethylene, and polypropylene. The binder content may be, for example, 0.5 to 10 parts by weight relative to 100 parts by weight of the negative electrode active material.

[0030] The negative electrode material may contain additives. Examples of additives include dispersants and conductive materials. Examples of dispersants include polycarboxylic acid (carboxylic acid copolymers), polyacrylic acid, polyether, and polymethylsiloxane. The content of the dispersant relative to 100% by mass of the negative electrode active material may be, for example, 0.1% to 1% by mass.

[0031] From the perspectives of easily achieving self-discharge suppression, electrolyte reduction suppression, further improving cycle life performance, and further reducing DC resistance, the negative electrode material may further contain at least one metal selected from the group consisting of bismuth (Bi), indium (In), lead (Pb), cadmium (Cd), thallium (Tl), and tin (Sn) as a conductive material. Among these, at least one metal selected from the group consisting of bismuth and indium is more preferred. These metals may be contained in the negative electrode material as metal oxides, and the metal oxides are preferably metal oxides containing at least one metal selected from the group consisting of bismuth and indium. That is, the negative electrode material is preferably containing at least one metal selected from the group consisting of bismuth oxide and indium oxide.

[0032] From the viewpoint of superior cycle life performance and reduction of DC resistance, the average particle size of the conductive material can be less than 0.32 μm, less than 0.30 μm, or less than 0.25 μm. From the viewpoint of processability in the mixing process, the average particle size of the conductive material can be 0.02 μm or more, 0.04 μm or more, or 0.06 μm or more. From these viewpoints, the average particle size of the conductive material can be 0.02 μm or more and less than 0.32 μm, 0.04 μm to 0.30 μm, or 0.06 μm to 0.25 μm. The average particle size of the conductive material is measured using a particle size distribution measuring device (manufactured by Nikkiso Co., Ltd., product name: Microtrac HRA9320-X100) and calculated as the median particle size (d50).

[0033] From the viewpoint of superior cycle life performance and reduction of DC resistance, the content of conductive material in the negative electrode material can be 1% or more, 3% or more, or 5% or more, based on the total mass of the electrode material. Alternatively, from the viewpoint of superior cycle life performance and reduction of DC resistance, the content of conductive material can be 50% or less, 30% or less, or 10% or less.

[0034] From the perspective of reducing the solubility of zinc oxide and easily suppressing the morphological changes of the negative electrode, the negative electrode material can contain more metal halides such as potassium fluoride, alkali metal hydroxides such as lithium hydroxide, and carbonates such as potassium carbonate and sodium carbonate. The content of metal halides relative to 100% by mass of the negative electrode active material can be, for example, 0.1% to 1% by mass.

[0035] From the perspective of easily achieving both excellent cycle life performance and excellent high-efficiency discharge performance, the thickness of the negative electrode is preferably 0.3 mm to 0.5 mm. Here, the thickness of the negative electrode refers to the total thickness of the negative electrode (the thickness after filling the current collector with negative electrode material and pressing it with rollers or the like to form a specified density (e.g., the thickness of the negative electrode material layer)).

[0036] The positive electrode may include, for example, a positive current collector and a positive electrode material supported by the positive current collector. The positive electrode can be either before or after chemical conversion.

[0037] The positive current collector forms the conductive path for the current from the positive electrode material. The positive current collector can be, for example, in the shape of a plate or sheet. It can also be a current collector with a three-dimensional mesh structure made of foamed metal, porous metal, perforated metal, or a felt-like material of metal fibers. The positive current collector contains materials that are both conductive and alkali-resistant.

[0038] As such materials, materials that are stable even at the reaction potential of the positive electrode can be used (materials with a redox potential higher than the reaction potential of the positive electrode, materials stabilized by forming a protective film such as an oxide film on the substrate surface in an alkaline aqueous solution, etc.). Furthermore, while oxygen is generated by the decomposition reaction of the electrolyte as a side reaction at the positive electrode, materials with high hydrogen overvoltage are preferred in terms of suppressing this side reaction. Specific examples of materials constituting the positive electrode current collector include: platinum; nickel (foamed nickel, etc.); and metal materials plated with metals such as nickel (copper, brass, steel, etc.). Among these, a positive electrode current collector containing foamed nickel is preferred. From the viewpoint of further improving high-efficiency discharge performance, it is preferable that at least the portion of the positive electrode material supporting the positive electrode material in the positive electrode current collector (positive electrode material support portion) is composed of foamed nickel.

[0039] The positive electrode material can be formed into a layer, for example. That is, the positive electrode can have a positive electrode material layer. The positive electrode material layer can be formed on the positive electrode current collector. When the positive electrode material support of the positive electrode current collector has a three-dimensional mesh structure, the positive electrode material can be filled between the meshes of the current collector to form the positive electrode material layer.

[0040] The positive electrode material includes a nickel-containing positive electrode active material (electrode active material). Examples of positive electrode active materials include nickel hydroxyl oxide (NiOOH) and nickel hydroxide. For example, the positive electrode material contains nickel hydroxyl oxide in the fully charged state and nickel hydroxide in the final discharged state. Based on the total mass of the positive electrode material, the content of the positive electrode active material can be, for example, 50% to 95% by mass.

[0041] The cathode material may contain other components besides the cathode active material as additives. Examples of additives include binders, conductive agents, and expansion inhibitors.

[0042] Examples of adhesives include hydrophilic or hydrophobic polymers. Specifically, carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), hydroxypropyl methyl cellulose (HPMC), sodium polyacrylate (SPA), and fluorinated polymers (polytetrafluoroethylene (PTFE), etc.) can be used as adhesives. The content of the adhesive relative to 100% by mass of the positive electrode active material is preferably, for example, 0.01% to 5% by mass.

[0043] Examples of conductive agents include cobalt compounds (metallic cobalt, cobalt oxide, cobalt hydroxide, etc.). The content of the conductive agent relative to 100% by mass of the positive electrode active material is preferably 1% to 20% by mass.

[0044] Examples of swelling inhibitors include zinc oxide. The content of the swelling inhibitor relative to 100% by mass of the positive electrode active material is preferably 0.01% to 5% by mass.

[0045] The spacer comprises a first spacer including at least a porous membrane and a second spacer including at least a nonwoven fabric. That is, in the zinc battery of this embodiment, a first spacer including at least a porous membrane and a second spacer including at least a nonwoven fabric are disposed between the positive and negative electrodes. The positional relationship between the first and second spacers is not particularly limited; the first spacer (porous membrane) may be disposed closer to the positive electrode than the second spacer (nonwoven fabric) (the second spacer (nonwoven fabric) may be disposed closer to the negative electrode than the first spacer (porous membrane)), and the nonwoven fabric may be disposed closer to the positive electrode than the porous membrane (the first spacer (porous membrane) may be disposed closer to the negative electrode than the second spacer (nonwoven fabric)). Two or more pieces of the porous membrane and nonwoven fabric may also be disposed between the positive and negative electrodes. The spacer may also further comprise a third spacer containing materials other than the porous membrane and nonwoven fabric.

[0046] The porous membrane referred to in this specification is a membrane with porous properties, meaning a membrane that provides electrical insulation between the positive and negative electrodes while allowing ion permeability. The porous membranes described in this specification do not include non-woven fabrics (details will be described later). Porous membranes can be those that meet conditions such as resistance to oxidation on the positive electrode side and reduction on the negative electrode side, and alkali resistance. Porous membranes can be in the form of sheets, plates, etc., and can also be processed into bags capable of housing the positive and / or negative electrodes.

[0047] Porous membranes can be formed from organic materials such as resins, inorganic materials, or organic-inorganic materials. Examples of organic materials include polymers such as polyolefins, nylon, and polyamide. Furthermore, porous membranes formed from organic materials can also include oxidation-resistant ion exchange resin membranes and cellophane-based recycled resin membranes. Examples of inorganic materials include oxides such as alumina, titanium dioxide, and silicon dioxide; nitrides such as aluminum nitride and silicon nitride; and sulfates such as barium sulfate and calcium sulfate. Porous membranes formed from inorganic materials can also be porous membranes containing particles of these inorganic materials. Examples of organic-inorganic materials include porous coordination polymers (PCP / MOF (Porous Coordination Polymer / Metal-Organic Framework)).

[0048] The porous membrane is preferably a microporous membrane. Specifically, the porous membrane is preferably a porous membrane with an average pore size and air permeability within the following ranges.

[0049] From the viewpoint of superior cycle life performance and reduction of DC resistance, the average pore size of the porous membrane is preferably 20 nm or more, 30 nm or more, or 40 nm or more. From the viewpoint of superior cycle life performance and reduction of DC resistance, the average pore size of the porous membrane is preferably 250 nm or less, 200 nm or less, or 150 nm or less. From these viewpoints, the average pore size of the porous membrane is preferably 20 nm to 250 nm, 20 nm to 200 nm, 20 nm to 150 nm, 30 nm to 250 nm, 30 nm to 200 nm, 30 nm to 150 nm, 40 nm to 250 nm, 40 nm to 200 nm, or 40 nm to 150 nm. The average pore size of the porous membrane can be measured using a mercury porosimeter (e.g., manufactured by Micromeritics, trade name: AutoPore IV9510).

[0050] From the perspective of superior cycle life performance and reduction of DC resistance, the preferred air permeability of porous membranes is 100 sec / 100 cc or higher, 150 sec / 100 cc or higher, or 200 sec / 100 cc or higher. From the perspective of superior cycle life performance and reduction of DC resistance, the preferred air permeability of porous membranes is 700 sec / 100 cc or lower, 600 sec / 100 cc or lower, or 500 sec / 100 cc or lower. According to these views, the air permeability of porous membranes can be 100 sec / 100 cc~700 sec / 100 cc, 100 sec / 100 cc~600 sec / 100 cc, 100 sec / 100 cc~500 sec / 100 cc, 150 sec / 100 cc~700 sec / 100 cc, 150 sec / 100 cc~600 sec / 100 cc, 150 sec / 100 cc~500 sec / 100 cc, 200 sec / 100 cc~700 sec / 100 cc, 200 sec / 100 cc~600 sec / 100 cc, or 200 sec / 100 cc~500 sec / 100 cc. The air permeability of porous membranes can be determined according to the method in JIS P 8117:2009.

[0051] From the viewpoint of superior cycle life performance and reduction of DC resistance, the thickness of the porous membrane is preferably 5 μm or more, 10 μm or more, or 15 μm or more. From the viewpoint of superior cycle life performance and reduction of DC resistance, the thickness of the porous membrane is preferably 100 μm or less, 75 μm or less, or 50 μm or less. From these viewpoints, the thickness of the porous membrane can be 5 μm to 100 μm, 5 μm to 75 μm, 5 μm to 50 μm, 10 μm to 100 μm, 10 μm to 75 μm, 10 μm to 50 μm, 15 μm to 100 μm, 15 μm to 75 μm, or 15 μm to 50 μm. The average thickness can be used as the thickness of the porous membrane. For example, five porous membranes of approximately 10 cm × 10 cm can be prepared, and the thickness at any nine points on each porous membrane can be measured. The average thickness can then be used as the thickness of the porous membrane.

[0052] From a hydrophilic perspective, porous membranes can contain anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants, and can also undergo surface treatments such as sulfonation, fluorine treatment, acrylic acid graft polymerization, corona discharge treatment, and plasma treatment. Hydrophilicity facilitates integration with the electrolyte and allows for the attainment of sufficient current density.

[0053] Nonwoven fabrics can be formed from cellulose fibers, polyaramid fibers, glass fibers, nylon fibers, vinylon fibers, polyester fibers, polyolefin fibers (polyethylene fibers, polypropylene fibers, etc.), rayon fibers, etc.

[0054] From the viewpoint of superior cycle life performance and reduction of DC resistance, the average pore size of the nonwoven fabric is preferably 0.5 μm or more, 1.0 μm or more, or 2.0 μm or more. From the viewpoint of superior cycle life performance and reduction of DC resistance, the average pore size of the nonwoven fabric is preferably 50 μm or less, 40 μm or less, 30 μm or less, or 20 μm. From these viewpoints, the average pore size of the nonwoven fabric can be 0.5 μm to 50 μm, 0.5 μm to 40 μm, 0.5 μm to 30 μm, 0.5 μm to 20 μm, 1.0 μm to 50 μm, 1.0 μm to 40 μm, 1.0 μm to 30 μm, 1.0 μm to 20 μm, 2.0 to 50 μm, 2.0 to 40 μm, 2.0 to 30 μm, or 2.0 to 20 μm. The method for determining the average pore size of the nonwoven fabric is the same as that used for the porous membrane.

[0055] From the perspective of superior cycle life performance and reduction of DC resistance, the optimal air permeability of nonwoven fabrics is 0.1 sec / 100 cc or higher, 0.15 sec / 100 cc or higher, or 0.2 sec / 100 cc or higher. From the perspective of superior cycle life performance and reduction of DC resistance, the optimal air permeability of nonwoven fabrics is 150 sec / 100 cc or lower, 100 sec / 100 cc or lower, or 50 sec / 100 cc or lower. According to these views, the air permeability of nonwoven fabrics can also be 0.1 sec / 100 cc~150 sec / 100 cc, 0.1 sec / 100 cc~100 sec / 100 cc, 0.1 sec / 100 cc~50 sec / 100 cc, 0.15 sec / 100 cc~150 sec / 100 cc, 0.15 sec / 100 cc~100 sec / 100 cc, 0.15 sec / 100 cc~50 sec / 100 cc, 0.2 sec / 100 cc~150 sec / 100 cc, 0.2 sec / 100 cc~100 sec / 100 cc, or 0.2 sec / 100 cc~50 sec / 100 cc. The method for measuring the air permeability of nonwoven fabrics is the same as that for measuring porous membranes described above.

[0056] From the perspective of further reducing DC resistance, the air permeability of nonwoven fabrics is preferably above 0.1 sec / 100 cc, above 0.15 sec / 100 cc, or above 0.2 sec / 100 cc, and below 20 sec / 100 cc, below 10 sec / 100 cc, or below 5 sec / 100 cc. From the same perspective, the air permeability of nonwoven fabrics can be 0.1 sec / 100 cc ~ 20 sec / 100 cc, 0.1 sec / 100 cc ~ 10 sec / 100 cc, 0.1 sec / 100 cc ~ 5 sec / 100 cc, 0.15 sec / 100 cc ~ 20 sec / 100 cc, 0.15 sec / 100 cc ~ 10 sec / 100 cc, 0.15 sec / 100 cc ~ 5 sec / 100 cc, 0.2 sec / 100 cc ~ 20 sec / 100 cc, 0.2 sec / 100 cc ~ 10 sec / 100 cc, or 0.2 sec / 100 cc ~ 5 sec / 100 cc.

[0057] From the viewpoint of superior cycle life performance and reduction of DC resistance, the thickness of the nonwoven fabric is preferably 20 μm or more, 30 μm or more, or 40 μm or more. From the viewpoint of superior cycle life performance and reduction of DC resistance, the thickness of the nonwoven fabric is preferably 250 μm or less, 200 μm or less, or 150 μm or less. From these viewpoints, the thickness of the nonwoven fabric can also be 20 μm to 250 μm, 20 μm to 200 μm, 20 μm to 150 μm, 30 μm to 250 μm, 30 μm to 200 μm, 30 μm to 150 μm, 40 μm to 250 μm, 40 μm to 200 μm, or 40 μm to 150 μm. As the thickness of the nonwoven fabric, the average thickness can be used, and the measurement method is the same as that used in the porous membrane.

[0058] Electrolytes may contain alkali metal hydroxides, surfactants, sugars, and solvents. Examples of solvents include water (e.g., ion-exchanged water).

[0059] The electrolyte may also contain, for example, potassium phosphate, potassium fluoride, potassium carbonate, sodium phosphate, sodium fluoride, zinc oxide, antimony oxide, titanium dioxide, etc.

[0060] Examples of alkali metal hydroxides include potassium hydroxide (KOH), sodium hydroxide (NaOH), and lithium hydroxide (LiOH). Alkali metal hydroxides can ionize (dissociate) in aqueous solutions and can also exist in the form of salts. From the viewpoint of easily suppressing the decrease in discharge capacitance when storing zinc batteries and easily obtaining excellent high-efficiency discharge performance, the alkali metal hydroxide is preferably at least one selected from the group consisting of potassium hydroxide and lithium hydroxide, and more preferably contains potassium hydroxide.

[0061] From the perspective of easily suppressing the decrease in discharge capacitance during zinc battery storage and easily obtaining excellent high-efficiency discharge performance, the content of alkali metal hydroxides in the electrolyte (total mass of alkali metal hydroxides) is preferably within the following range based on the total mass of the electrolyte: The content of alkali metal hydroxides is preferably 10% by mass or more, 15% by mass or more, 20% by mass or more, 25% by mass or more, or 30% by mass or more. The content of alkali metal hydroxides is preferably 50% by mass or less, 45% by mass or less, 40% by mass or less, or 35% by mass or less. From these perspectives, the content of alkali metal hydroxides is preferably 10% by mass to 50% by mass.

[0062] From the perspective of easily suppressing the decrease in discharge capacitance during zinc battery storage and easily obtaining excellent high-efficiency discharge performance, the potassium hydroxide content in the electrolyte, based on the total mass of the electrolyte, is preferably within the following ranges: The potassium hydroxide content is preferably 10% by mass or more, 15% by mass or more, 20% by mass or more, 25% by mass or more, or 30% by mass or more. The potassium hydroxide content is preferably 50% by mass or less, 45% by mass or less, 40% by mass or less, or 35% by mass or less. From these perspectives, the potassium hydroxide content is preferably 10% by mass to 50% by mass.

[0063] From the perspective of easily suppressing the decrease in discharge capacitance during zinc battery storage and easily obtaining excellent high-efficiency discharge performance, the lithium hydroxide content in the electrolyte, based on the total mass of the electrolyte, is preferably within the following ranges: The lithium hydroxide content is preferably 0.1% by mass or more, 0.3% by mass or more, 0.5% by mass or more, 0.8% by mass or more, or 1% by mass or more. The lithium hydroxide content is preferably 3% by mass or less, 2% by mass or less, 1.5% by mass or less, or 1.2% by mass or less. From these perspectives, the lithium hydroxide content is preferably 0.1% by mass to 3% by mass.

[0064] Examples of surfactants used in electrolytes include di-dodecyl dimethyl ammonium bromide, tetradecyl trimethyl ammonium bromide, polyoxyethylene decyl ether, and polyoxyethylene alkyl ether phosphate. From the perspectives of easily achieving excellent cycle life performance and easily suppressing the decrease in discharge capacitance, the presence of tetradecyl trimethyl ammonium bromide is preferred.

[0065] The content of surfactants in the electrolyte (total mass of surfactants) is preferably within the following ranges based on the total mass of the electrolyte. From the viewpoint of easily suppressing the reduction in discharge performance of the zinc battery, the surfactant content is preferably 0.001% by mass or more, 0.003% by mass or more, 0.005% by mass or more, or 0.01% by mass or more. From the viewpoint of easily obtaining excellent cycle life performance and easily suppressing the reduction in discharge capacitance, the surfactant content is preferably 5% by mass or less, 2.5% by mass or less, 1% by mass or less, 0.7% by mass or less, or 0.5% by mass or less.

[0066] From these perspectives, the surfactant content is preferably 0.001% to 5% by mass. From the perspective of more easily obtaining excellent cycle life performance and more easily suppressing the decrease in discharge capacitance, the surfactant content is particularly preferably 0.01% to 0.5% by mass.

[0067] As sugars, monosaccharides, disaccharides, trisaccharides, and polysaccharides (excluding sugars equivalent to disaccharides or trisaccharides) can be used. Examples of monosaccharides include: glucose, fructose, galactose, arabinose, ribose, mannose, xylose, sorbitol, rhamnose, trehalose, deoxyribose, and their hydrates. Examples of disaccharides include: sucrose, maltose, trehalose, cellodisaccharide, gentiobiose, lactose, melibiose, and their hydrates. Examples of trisaccharides include: kestose, melicitose, gentiobiose, raffinose, gentiobiose, melibiose, and their hydrates. Examples of polysaccharides include cyclodextrins (e.g., γ-cyclodextrin) and stachyose.

[0068] The sugar content in the electrolyte, based on the total mass of the electrolyte, is preferably within the following ranges. From the viewpoint of easily suppressing the decrease in discharge capacitance during zinc battery storage and easily obtaining excellent high-efficiency discharge performance, the sugar content is preferably 0.1% by mass or more, 0.3% by mass or more, 0.5% by mass or more, 0.8% by mass or more, or 1% by mass or more. From the viewpoint of easily suppressing the decrease in discharge capacitance during zinc battery storage and easily obtaining excellent high-efficiency discharge performance, the sugar content is preferably 5% by mass or less, 4.5% by mass or less, 4% by mass or less, 3.5% by mass or less, or 3% by mass or less. From these viewpoints, the sugar content is preferably 0.1% by mass to 5% by mass.

[0069] From the viewpoint of more easily suppressing the decrease in discharge capacitance when storing zinc batteries, the sugar content in the electrolyte is preferably 1.2% by mass or more, 1.5% by mass or more, 1.8% by mass or more, 2% by mass or more, 2.2% by mass or more, 2.5% by mass or more, 2.7% by mass or more, or 3% by mass or more. The sugar content can also be 3.5% by mass or more, 4% by mass or more, 4.5% by mass or more, or 5% by mass or more. From the viewpoint of more easily obtaining excellent high-efficiency discharge performance, the sugar content is preferably 2.7% by mass or less, 2.5% by mass or less, 2.2% by mass or less, 2% by mass or less, 1.7% by mass or less, 1.5% by mass or less, 1.2% by mass or less, or 1% by mass or less. From these viewpoints, the sugar content can also be 1.2% by mass to 2.7% by mass. Based on the total amount of electrolyte, it can be less than 0.5 mol / L.

[0070] The manufacturing method of the nickel-zinc battery described above includes, for example, a component manufacturing step to obtain the components of the zinc battery; and an assembly step to assemble the components to obtain the zinc battery. In the component manufacturing step, at least electrodes (positive and negative electrodes) are obtained.

[0071] Electrodes can be obtained, for example, by adding a solvent (e.g., water) to the raw materials of electrode materials (positive electrode material and negative electrode material) and mixing them to obtain an electrode material paste (paste-like electrode material), and then filling the electrode material paste into the current collector to form an electrode material layer.

[0072] Examples of raw materials for positive electrode materials include: raw materials for positive electrode active substances (e.g., nickel hydroxide), additives (e.g., the binder mentioned above). Examples of raw materials for negative electrode materials include: raw materials for negative electrode active substances (e.g., metallic zinc, zinc oxide, and zinc hydroxide), additives (e.g., binders).

[0073] One method for forming an electrode material layer is to coat or fill an electrode material paste onto a current collector and then dry it to obtain the electrode material layer. The density of the electrode material layer can be increased as needed by using methods such as pressing with rollers.

[0074] In the assembly step, for example, positive and negative electrodes obtained in the component manufacturing step are alternately stacked with spacers in between. Then, positive electrodes and negative electrodes are connected to each other using bonding plates to create an electrode group. Subsequently, after the electrode group is placed in an electrolytic cell, a cover is attached to the upper surface of the electrolytic cell to obtain an unchemically converted zinc battery (nickel-zinc battery).

[0075] In the fabrication of electrode groups, as a method for placing spacers between the positive and negative electrodes, a porous membrane and a nonwoven fabric can be pre-laminated and then placed between the positive and negative electrodes, or the porous membrane and the nonwoven fabric can be placed separately. Alternatively, the positive and negative electrodes can be housed separately in a porous membrane processed into a bag shape, with a nonwoven fabric placed between the positive and negative electrodes, and a spacer (a spacer having a first spacer containing a porous membrane and a second spacer containing a nonwoven fabric) placed between the positive and negative electrodes.

[0076] Next, the electrolyte is injected into the electrolytic cell of the unconverted zinc battery and left for a certain period of time. Then, by charging under specified conditions and undergoing chemical conversion, a zinc battery (nickel-zinc battery) is obtained. The chemical conversion conditions can be adjusted according to the properties of the electrode active materials (positive and negative electrode active materials). For example, a chemically converted nickel-zinc battery can be produced by charging at an ambient temperature of 25°C, 32 mA, and for 12 hours.

[0077] The above describes an example of a nickel-zinc battery (e.g., a nickel-zinc secondary battery) with a nickel electrode as the positive electrode. However, the zinc battery can be an air-zinc battery (e.g., an air-zinc secondary battery) with an air electrode as the positive electrode, or a silver-zinc battery (e.g., a silver-zinc secondary battery) with a silver oxide electrode as the positive electrode.

[0078] As the air electrode in an air-zinc battery, a known air electrode used in air-zinc batteries can be used. The air electrode may include, for example, an air electrode catalyst or an electronically conductive material. As an air electrode catalyst, an air electrode catalyst that also functions as an electronically conductive material can be used.

[0079] As an air electrode catalyst, it can function as the positive electrode in an air-zinc battery, and various air electrode catalysts that can use oxygen as the positive electrode active material can be used. Examples of air electrode catalysts include: carbon-based materials (such as lead oxide), metal materials (such as platinum and nickel), and inorganic oxide materials (such as perovskite oxides, manganese dioxide, nickel oxide, cobalt oxide, and spinel oxide). The shape of the air electrode catalyst is not particularly limited; for example, it can also be in particle form. The amount of air electrode catalyst used in the air electrode can be 5% to 70% by volume, 5% to 60% by volume, or 5% to 50% by volume relative to the total volume of the air electrode.

[0080] As an electronically conductive material, materials that are conductive and capable of conducting electrons between the air electrode catalyst and the spacer can be used. Examples of electronically conductive materials include: carbon blacks such as Ketjen black, acetylene black, channel black, furnace black, lamp black, and thermal black; graphite materials such as natural black lead, artificial black lead, and expanded black lead, such as flake black lead; conductive fibers such as carbon fibers and metal fibers; metal powders such as copper, silver, nickel, and aluminum; organic electronically conductive materials such as polystyrene derivatives; and any mixtures thereof. The shape of the electronically conductive material can be particle-like or other shapes. It is preferable to use the electronically conductive material in a form that creates a continuous phase in the thickness direction in the air electrode. For example, the electronically conductive material can be a porous material. In addition, the electronically conductive material can be in the form of a mixture or composite with the air electrode catalyst, as mentioned above, and can also function as an air electrode catalyst that functions as an electronically conductive material. The amount of electronically conductive material used in the air electrode can be 10% to 80% of the total volume relative to the air electrode, or 15% to 80% of the total volume, or 20% to 80% of the total volume.

[0081] As the silver oxide electrode in a silver-zinc battery, a known silver oxide electrode used in silver-zinc batteries can be used. The silver oxide electrode, for example, comprises silver oxide (I). [Example]

[0082] The present invention will now be specifically described through examples. However, the present invention is not limited to the examples described below.

[0083] (Example 1) <Making the Negative Electrode> A tin-plated steel sheet with a 50% aperture ratio was prepared as the negative electrode current collector. Then, specified amounts of zinc oxide (manufactured by Mitsui Metals & Mining Co., Ltd., general grade), metallic zinc (manufactured by Mitsui Metals & Mining Co., Ltd., MA-ZB (trade name)), bismuth oxide (manufactured by Corefront Corporation, 4115CB (trade name)), indium oxide (manufactured by Corefront Corporation, 1710CY (trade name)), polytetrafluoroethylene (PTFE, manufactured by Daikin Industries, Ltd., D210-C (trade name)), polyvinyl alcohol (PVA, saponification degree 99, manufactured by Kuraray Corporation, Poval 60-98 (trade name)), and ion-exchanged water were added and mixed to prepare the negative electrode material paste. At this point, the water content of the negative electrode material paste, adjusted to a solid composition mass ratio of "zinc oxide: metallic zinc: bismuth oxide: indium oxide: PTFE: PVA = 69.6:22.8:2.5:1.0:3.0:1.1", is set to 20% by mass based on the total mass of the negative electrode material paste. The negative electrode material paste is then coated onto the negative electrode current collector and dried at 80°C for 30 minutes. Finally, it is press-formed using a roller to obtain a non-chemically converted negative electrode with the negative electrode material (negative electrode material layer).

[0084] <The Making of the Positive Electrode> A lattice containing 95% porosity of foamed nickel is prepared and pressurized to form a positive electrode current collector. Then, specified amounts of cobalt-coated nickel hydroxide powder (manufactured by Gold Shine Energy Material Co., Ltd., Y6 (trade name)), metallic cobalt (manufactured by NIKKOSHI Co., Ltd., EXTRA FINE (trade name)), cobalt hydroxide (manufactured by Ise Chemical Industry Co., Ltd.), yttrium oxide (manufactured by Fujifilm and Koko Pure Chemical Co., Ltd., reagent grade), carboxymethyl cellulose (CMC, manufactured by Weiyi Chemical (Suzhou) Co., Ltd., BH90-3 (trade name)), polytetrafluoroethylene (PTFE, manufactured by Daikin Industries Co., Ltd., D210-C (trade name)), and ion-exchanged water are added and mixed to prepare a positive electrode material paste. At this point, the mass ratio of the solid components is adjusted to "nickel hydroxide: cobalt metal: yttrium oxide: cobalt hydroxide: CMC: PTFE = 88.0:10.3:1.0:0.3:0.3:0.1". The moisture content of the positive electrode material paste is adjusted to 27.5% by mass based on the total mass of the positive electrode material paste. Then, the positive electrode material paste is coated onto the positive electrode material support of the positive electrode current collector and dried at 80°C for 30 minutes. Next, it is pressed using a roller to obtain a non-chemically converted positive electrode with a positive electrode material layer.

[0085] <Preparation of spacers> In the spacers, UP3355 (manufactured by Ube Industries, Ltd., trade name, air permeability: 440 sec / 100 mL, average pore size: 80 nm, thickness: 25 μm) was used as the first spacer, and non-woven fabric (manufactured by Kotaka Paper Industries, Ltd., trade name: VL-100, air permeability: 0.3 sec / 100 mL, average pore size: 9.3 μm, thickness: 100 μm) was used as the second spacer. Before battery assembly, the porous membrane was hydrophilized using the surfactant Triton-X100 (manufactured by Sigma-Aldrich Japan Ltd., trade name). The hydrophilization treatment was carried out by immersing the porous membrane in an aqueous solution containing 1% by mass of Triton-X100 for 24 hours, followed by drying at room temperature (25°C) for 1 hour. Furthermore, the air permeability of the porous membrane is expressed as a value after hydrophilic treatment. The porous membrane is then cut to a specified size, folded in half with the folded portion as the bottom, and the sides are heat-sealed to form a bag shape. Non-woven fabric cut to the specified size is used. Furthermore, the air permeability described here is a value obtained using the method according to JIS P 8117:2009.

[0086] <Electrolyte Adjustment> An electrolyte was prepared by mixing ion-exchanged water, potassium hydroxide (KOH), lithium hydroxide (LiOH), tetradecyltrimethylammonium bromide, and sucrose (relative to the total mass of the electrolyte, potassium hydroxide: 30.0% by mass, lithium hydroxide: 1.0% by mass, tetradecyltrimethylammonium bromide: 0.1% by mass, sucrose: 2.0% by mass, and ion-exchanged water: 66.9% by mass).

[0087] <Making of Nickel-Zinc Batteries> One positive electrode (unconverted positive electrode) and one negative electrode (unconverted negative electrode) are respectively housed in a porous membrane (first spacer) processed into a pouch shape. After stacking the positive electrode housed in the porous membrane, the negative electrode housed in the porous membrane, and a non-woven fabric (second spacer), electrode groups (electrode groups) are formed by connecting electrodes of the same polarity together using overlapping tabs. Each electrode group consists of two positive electrodes and three negative electrodes, with a non-woven fabric piece placed between each of the positive and negative electrodes (between the porous membrane on the positive electrode side and the porous membrane on the negative electrode side). After placing this electrode group in an electrolytic cell, a cover is attached to the upper surface of the electrolytic cell, and the electrolyte is injected into the electrolytic cell to obtain an unconverted nickel-zinc battery. Then, the battery is charged at an ambient temperature of 25°C, 32 mA, and for 12 hours to produce a nickel-zinc battery with a nominal capacity of 320 mAh.

[0088] (Example 2) Except that bismuth oxide was not used in the negative electrode material paste, the nickel-zinc battery of Example 2 was made in the same manner as in Example 1.

[0089] (Example 3) Except that PVA with a saponification degree of 92.5 (manufactured by Kuraray Co., Ltd., Kuraray Poval 60-98 (trade name)) was used instead of PVA, the nickel-zinc battery of Example 3 was made in the same manner as in Example 1.

[0090] (Example 4) Except that the proportions of each component were adjusted so that the PVA content was as shown in Table 1, the nickel-zinc battery of Example 5 was prepared in the same manner as in Example 1. Furthermore, the contents shown in Table 1 are based on the total mass of the negative electrode material after chemical conversion.

[0091] (Example 5) Except for changing the porous membrane to UP3364 (manufactured by Ube Industries, Inc., trade name, air permeability: 320 sec / 100 mL, average pore size: 68 nm, thickness: 20 μm), the nickel-zinc battery of Example 5 was prepared in the same manner as in Example 1.

[0092] (Example 6) Except for changing the nonwoven fabric to one with an air permeability of 144 sec / 100 mL, an average pore size of 3.3 μm, and a thickness of 30 μm, the nickel-zinc battery of Example 6 was made in the same manner as in Example 1.

[0093] (Comparative Example 1) The nickel-zinc battery of Comparative Example 1 was manufactured in the same manner as in Example 1, except that a first spacer containing a porous membrane was not used as a spacer (only a second spacer containing non-woven fabric was used).

[0094] (Comparative Example 2) The nickel-zinc battery of Comparative Example 2 was manufactured in the same manner as in Example 1, except that a second spacer containing non-woven fabric was not used as a spacer (only a first spacer containing a porous membrane was used).

[0095] (Comparative Example 3) Except that carboxymethyl cellulose (CMC, manufactured by Weiyi Chemical (Suzhou) Co., Ltd., BH90-3 (trade name)) was used instead of PVA, the nickel-zinc battery of Comparative Example 3 was prepared in the same manner as in Example 1.

[0096] (Comparative Example 4) Except that hydroxyethyl cellulose (HEC, manufactured by Sumitomo Seika Co., Ltd., AV-15F (trade name)) was used instead of PVA, the nickel-zinc battery of Comparative Example 4 was prepared in the same manner as in Example 1.

[0097] <Evaluation of Cycle Life Performance> The cycle life performance of the nickel-zinc batteries of Examples 1 to 6 and Comparative Examples 1 to 4 was evaluated. The specific evaluation methods are shown below, and the results are presented in Table 2.

[0098] At an ambient temperature of 70°C, the nickel-zinc battery was charged at a constant voltage of 105.7 mA (0.33 C) and 1.88 V until the current decayed to 16 mA (0.05 C). Then, the nickel-zinc battery was discharged at a constant current of 105.7 mA (0.33 C) until the battery voltage reached 1.1 V. This constituted one cycle of the test. The cycle life was defined as the number of cycles from 100% discharge capacitance to 70% discharge capacitance. The cycle life performance was evaluated according to the evaluation criteria a~c shown below. s: The number of iterations is 90 or more. a: The number of iterations is more than 60 but less than 90. b: The number of iterations is more than 30 but less than 60. c: The number of iterations is less than 30.

[0099] Furthermore, the "C" refers to the magnitude of the current when the rated capacitor is discharged at a constant current during a self-full charge state. The "C" is defined as "discharge current value (A) / battery capacity (Ah)". For example, the current that can discharge the rated capacitor in 1 hour is defined as "1 C", and the current that can discharge it in 2 hours is defined as "0.5 C".

[0100] <Evaluation of DC Resistance> The direct current resistance (DCR) of the nickel-zinc batteries of Examples 1 to 6 and Comparative Examples 1 to 4 was evaluated. The specific evaluation method is shown below, and the results are presented in Table 2.

[0101] For the nickel-zinc batteries of Examples 1 to 6 and Comparative Examples 1 to 4, after charging at a constant voltage of 1.9 V at 25°C (charging was stopped at the point where the current decayed to 16 mA (0.05 C), they were discharged at a constant current of 160 mA (0.5 C), 320 mA (1 C), 640 mA (2 C), and 960 mA (3 C) for 1 second at -30°C, respectively. The DC resistance (DCR) per unit area of ​​the total electrode was calculated according to the following formula. After constant current discharge, they were charged at a constant current of 1 C (current value 320 mA) at -30°C, with the discharge capacitance equal to the charging capacitance. DCR={(ΔV 0.5 CV)(I 0.5 CI)+(ΔV 1.0 CV)(I 1.0 CI)+(ΔV 2.0 CV)(I 2.0 CI)+(ΔV 3.0 CV)(I 3.0 CI)} / {(I 0.5 CI) 2+(I 1.0 CI) 2+(I 2.0 CI) 2+(I 3.0 CI) 2}·AE In the formula, I = (I0.5C + I1.0C + I2.0C + I3.0C) / 4, V = (ΔV0.5C + ΔV1.0C + ΔV2.0C + ΔV3.0C) / 4, where I0.5C, I1.0C, I2.0C, and I3.0C represent the discharge current values ​​equivalent to discharge rates of 0.5C, 1.0C, 2.0C, and 3.0C, respectively, and ΔV0.5C, ΔV1.0C, ΔV2.0C, and ΔV3.0C represent the voltage change after 1 second within their respective discharge current values. AE represents the total electrode area.

[0102] The DCR obtained using the method described above was evaluated according to the evaluation criteria shown in a to c below. a: DC resistance less than 10 mΩ·cm² b: DC resistance is 10 mΩ·cm² or higher and less than 11 mΩ·cm². c: DC resistance of 11 mΩ·cm² or higher

[0103] <Electrode Evaluation> The contactability of the negative electrodes was evaluated using the negative electrodes prepared in Examples 1 to 6 and Comparative Examples 1 to 4. The specific evaluation method is shown below, and the results are presented in Table 2.

[0104] After the negative electrode was dropped naturally from a height of 1 m to the ground, its mass was measured. The contact ratio (%) was calculated based on the negative electrode masses before and after the drop test using the following formula. The contact performance was evaluated according to the evaluation criteria A to C shown below. Contact ratio (%) = (Negative electrode mass after drop test / Negative electrode mass before drop test) × 100 A: The close contact rate is over 95%. B: The close contact rate is above 90% but less than 95%. C: Close contact rate less than 90%

[0105] [Table 1] Anode material Structure of spacers adhesive Bismuth oxide The presence or absence substance name degree of saponification Content (mass %) Example 1 PVA 99 1.1 have Porous membrane + non-woven fabric Example 2 PVA 99 1.1 none Porous membrane + non-woven fabric Example 3 PVA 92.5 1.1 have Porous membrane + non-woven fabric Example 4 PVA 99 0.9 have Porous membrane + non-woven fabric Example 5 PVA 99 1.1 have Porous membrane + non-woven fabric (The type of porous membrane differs from that in Example 1) Example 6 PVA 99 1.1 have Porous membrane + non-woven fabric (The type of non-woven fabric is different from that in Example 1) Comparative Example 1 PVA 99 1.1 have Only non-woven fabric Comparative Example 2 PVA 99 1.1 have Porous membranes only Comparative Example 3 CMC - 1.1 have Porous membrane + non-woven fabric Comparative Example 4 HEC - 1.1 have Porous membrane + non-woven fabric

[0106] [Table 2] evaluate Cycle life performance DCR Negative electrode tightness Example 1 s a A Example 2 a b A Example 3 a a A Example 4 a b A Example 5 s b A Example 6 a a A Comparative Example 1 c a A Comparative Example 2 b c A Comparative Example 3 c c C Comparative Example 4 b c B

[0107] Compared with the zinc batteries of Comparative Examples 1 to 4, the zinc batteries of Examples 1 to 6 achieved a balance between cycle life performance and reduced DC resistance. Furthermore, compared with Comparative Examples 3 to 4, Examples 1 to 6 also exhibited superior negative electrode adhesion. When compared with Comparative Examples 3 to 4, it is believed that the zinc batteries of Examples 1 to 6, through the use of polyvinyl alcohol, improved the adhesion between active materials or between active materials and the current collector, and achieved excellent cycle life performance and reduced DC resistance by homogenizing the zinc dissolution and desorption reaction.

[0108] none

Claims

1. A zinc battery comprising a positive electrode, a negative electrode, an electrolyte, and a spacer, wherein the negative electrode has a negative electrode current collector and a negative electrode material supported by the negative electrode current collector, the negative electrode material containing a negative electrode active material comprising zinc and polyvinyl alcohol, and the spacer having a first spacer comprising a porous membrane and a second spacer comprising a nonwoven fabric.

2. The zinc battery as claimed in claim 1, wherein, The negative electrode material contains a metal oxide comprising at least one selected from the group consisting of bismuth and indium.

3. The zinc battery as described in claim 1 or claim 2, wherein, The negative current collector comprises at least a portion of a tin-plated metallic material on its surface.

4. The zinc battery as described in claim 1 or claim 2, wherein, The electrolyte contains alkali metal hydroxides.

5. The zinc battery as described in claim 1 or claim 2, wherein, The electrolyte contains surfactants.

6. The zinc battery as described in claim 1 or claim 2, wherein, The electrolyte contains sugars.

7. The zinc battery as described in claim 1 or claim 2, wherein, The average degree of polymerization of the polyvinyl alcohol is 250 to 2400.

8. The zinc battery as described in claim 1 or claim 2, wherein, The degree of saponification of the polyvinyl alcohol is 90 mol% to 99.9 mol.

9. The zinc battery as described in claim 1 or claim 2, wherein, Based on the total mass of the negative electrode material, the content of polyvinyl alcohol is 0.1% to 10% by mass.

10. The zinc battery as described in claim 1 or claim 2, wherein, The average pore size of the porous membrane is 20 nm to 250 nm.

11. The zinc battery as described in claim 1 or claim 2, wherein, The average pore size of the nonwoven fabric is 0.5 μm to 50 μm.