Anode for zinc secondary battery and zinc secondary battery

Abstract

To provide a zinc battery with excellent cycle life performance.SOLUTION: A negative electrode for a zinc battery includes a current collector, and a negative electrode material supported by the current collector, and the negative electrode material includes a negative electrode active material containing zinc, and at least one halide salt selected from the group consisting of chloride salts, bromide salts, and iodide salts.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Known zinc batteries include nickel-zinc batteries, air-zinc batteries, and silver-zinc batteries. For example, nickel-zinc batteries are aqueous batteries that use an aqueous electrolyte such as an aqueous potassium hydroxide solution, and therefore are highly safe. In addition, the combination of zinc electrodes and nickel electrodes is known to provide a high electromotive force for an aqueous battery. Furthermore, nickel-zinc batteries have excellent input / output performance and low cost, and therefore their applicability to industrial applications (e.g., backup power sources, etc.) and automotive applications (e.g., hybrid vehicles, etc.) is being considered.

[0003] In zinc batteries, zinc hydroxide (Zn(OH)2) is produced by the discharge reaction. Zinc hydroxide is soluble in the electrolyte, and when zinc hydroxide dissolves in the electrolyte, it becomes zinc tetrahydroxide ions ([Zn(OH)4] 2- ) diffuses into the electrolyte. As a result, the morphological change (deformation) of the negative electrode progresses and the distribution of the charging current becomes uneven, causing zinc to precipitate locally on the negative electrode, resulting in the formation of dendrites (branched crystals). In conventional zinc batteries, when dendrites grow due to repeated charging and discharging, they can penetrate the separator, causing a short circuit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 58-126665 Summary of the Invention [Problem to be solved by the invention]

[0005] In the zinc batteries described above, there is a demand for improving the life performance (for example, cycle life performance).

[0006] Therefore, an object of the present invention is to provide a zinc battery having excellent cycle life performance. [Means for solving the problem]

[0007] One aspect of the present invention relates to an anode for a zinc battery, comprising a current collector and an anode material supported on the current collector, the anode material containing a zinc-containing anode active material and at least one halide salt selected from the group consisting of chloride salts, bromide salts, and iodide salts.

[0008] According to the negative electrode of the above aspect, a zinc battery having excellent cycle life performance can be obtained.

[0009] In one embodiment, the anode material contains a chloride salt, in another embodiment, the anode material contains a bromide salt, and in yet another embodiment, the anode material contains an iodide salt.

[0010] The above-mentioned halide salt is preferably at least one selected from the group consisting of alkali metal halides and ammonium halides.

[0011] The negative electrode is preferably for a nickel-zinc battery.

[0012] Another aspect of the present invention relates to a zinc battery comprising the above-mentioned negative electrode. Effect of the Invention

[0013] According to the present invention, a zinc battery having excellent cycle life performance can be provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] In this specification, the numerical range indicated by "~" indicates a range including the numerical values ​​described before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper limit or lower limit of a numerical range of a certain stage can be arbitrarily combined with the upper limit or lower limit of a numerical range of another stage. In the numerical ranges described in this specification, the upper limit or lower limit of the numerical range may be replaced with a value shown in an experimental example. "A or B" may include either A or B, or may include both. Unless otherwise specified, the materials exemplified in this specification may be used alone or in combination of two or more types. In this specification, the amount of each component used in the composition means the total amount of the multiple substances present in the composition when multiple substances corresponding to each component are present in the composition, unless otherwise specified. In this specification, the term "film" or "layer" includes a structure having a shape formed on the entire surface when observed as a plan view, as well as a structure having a shape formed on a part of the surface. In this specification, the term "process" refers not only to an independent process, but also to a process that cannot be clearly distinguished from other processes, as long as the intended effect of the process is achieved.

[0015] Preferred embodiments of the present invention will be described below, however, the present invention is not limited to the following embodiments.

[0016] One embodiment of the present invention relates to an electrode (negative electrode for zinc battery) used as the negative electrode of a zinc battery. Here, the zinc battery is a battery (for example, an alkaline zinc battery) that uses a zinc electrode. Examples of zinc batteries include nickel-zinc batteries (for example, nickel-zinc secondary batteries) whose positive electrode is a nickel electrode; air-zinc batteries (for example, air-zinc secondary batteries) whose positive electrode is an air electrode; and silver-zinc batteries (for example, silver-zinc secondary batteries) whose positive electrode is a silver oxide electrode.

[0017] The negative electrode of this embodiment is, for example, in the form of a plate, and includes a current collector (negative electrode current collector) and a negative electrode material supported by the current collector.

[0018] The current collector constitutes a conductive path for the current from the negative electrode material. The current collector has, for example, a flat plate shape, a sheet shape, or the like. The current collector may be a three-dimensional mesh-structured current collector constituted by foam metal, expanded metal, punching metal, felt-like material of metal fiber, or the like. The current collector is constituted by a material having electrical conductivity and alkali resistance. For example, a material that is stable even at the reaction potential of the negative electrode (a material having an oxidation-reduction potential more noble than the reaction potential of the negative electrode, a material that forms a protective film such as an oxide film on the substrate surface in an alkaline aqueous solution to stabilize it, etc.) can be used as such a material. In addition, in the negative electrode of a zinc battery, a decomposition reaction of the electrolyte proceeds as a side reaction, generating hydrogen gas, and a material with a high hydrogen overvoltage is preferable in that it can suppress the progress of such a side reaction. Specific examples of materials that constitute the current collector include zinc; lead; tin; and metal materials (copper, brass, steel, nickel, etc.) plated with metals such as tin.

[0019] The negative electrode material is, for example, layered. In this embodiment, a layered negative electrode material (negative electrode material layer) may be formed on a current collector, and when the current collector has a three-dimensional mesh structure, the negative electrode material may be filled between the meshes of the current collector to form a negative electrode material layer.

[0020] The negative electrode material contains a negative electrode active material containing zinc, and at least one type of halide salt selected from the group consisting of chloride salts, bromide salts, and iodide salts.

[0021] Examples of the negative electrode active material containing zinc include metallic zinc, zinc oxide, zinc hydroxide, etc. The negative electrode material contains, for example, metallic zinc in a fully charged state, and contains zinc oxide and zinc hydroxide in an end-of-discharge state.

[0022] The content of the negative electrode active material is preferably in the following range based on the total mass of the negative electrode material. From the viewpoint of easily achieving both excellent life performance and discharge performance, the content of the negative electrode active material is preferably 50 mass% or more, more preferably 70 mass% or more, and even more preferably 75 mass% or more. From the viewpoint of easily achieving both excellent life performance and discharge performance, the content of the negative electrode active material is preferably 95 mass% or less, more preferably 90 mass% or less, and even more preferably 85 mass% or less. From these viewpoints, the content of the negative electrode active material is preferably 50 to 95 mass%.

[0023] Chloride salts, for example, ionize (dissociate) in the electrolyte to produce chloride ions (Cl - Chloride salts include potassium chloride (KCl), sodium chloride (NaCl), lithium chloride (LiCl), lead dichloride (PbCl2), zinc chloride (ZnCl2), aluminum chloride (AlCl3), indium chloride (InCl3), tin chloride (SnCl2), ammonium chloride (NH4Cl), calcium chloride (CaCl2), magnesium chloride (MgCl2), phosphorus trichloride (PCl3), and phosphorus pentachloride (PCl5).

[0024] Bromide salts, for example, ionize (dissociate) in an electrolyte to produce bromide ions (Br - Bromide salts include potassium bromide (KBr), sodium bromide (NaBr), lithium bromide (LiBr), lead dibromide (PbBr2), zinc bromide (ZnBr2), aluminum bromide (AlBr3), indium bromide (InBr3), tin bromide (SnBr2), ammonium bromide (NH4Br), calcium bromide (CaBr2), magnesium bromide (MgBr2), phosphorus tribromide (PBr3), and phosphorus pentabromide (PBr5).

[0025] Iodide salts, for example, ionize (dissociate) in an electrolyte to produce iodide ions (I -) Iodide salts include potassium iodide (KI), sodium iodide (NaI), lithium iodide (LiI), lead diiodide (PbI2), zinc iodide (ZnI2), aluminum iodide (AlI3), indium iodide (InI3), tin iodide (SnI2), ammonium iodide (NH4I), calcium iodide (CaI2), magnesium iodide (MgI2), phosphorus triiodide (PI3), and phosphorus pentaiodide (PI5).

[0026] These halide salts may be present in the negative electrode material in the form of a salt compound, or may be present in the negative electrode material in the form of dissociation into ions. As the halide salt, from the viewpoint of further improving the cycle life performance, it is preferable to use at least one selected from the group consisting of alkali metal halides and ammonium halides, and it is more preferable to use ammonium halides. That is, as the halide salt, it is preferable to use at least one selected from the group consisting of alkali metal chlorides, alkali metal bromides, alkali metal iodides, ammonium chloride, ammonium bromide, and ammonium iodide, and it is more preferable to use at least one selected from the group consisting of ammonium chloride, ammonium bromide, and ammonium iodide. As the alkali metal halide, potassium halide is preferably used.

[0027] From the viewpoint of further improving the cycle life performance, among the halide salts, it is preferable to use at least one selected from the group consisting of bromide salts and iodide salts, and it is more preferable to use bromide salts.

[0028] The content of the chloride salt is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1% by mass or more, based on the total mass of the negative electrode material, from the viewpoint of further improving cycle life performance. The content of the chloride salt is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, based on the total mass of the negative electrode material, from the viewpoint of easily achieving both excellent life performance and excellent discharge performance.

[0029] The content of the bromide salt is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1% by mass or more, based on the total mass of the negative electrode material, from the viewpoint of further improving cycle life performance. The content of the bromide salt is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, based on the total mass of the negative electrode material, from the viewpoint of easily achieving both excellent life performance and excellent discharge performance.

[0030] The content of the iodide salt is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1% by mass or more, based on the total mass of the negative electrode material, from the viewpoint of further improving cycle life performance. The content of the iodide salt is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, based on the total mass of the negative electrode material, from the viewpoint of easily achieving both excellent life performance and excellent discharge performance.

[0031] From the viewpoint of further improving cycle life performance, the total content of the chloride salt, the bromide salt, and the iodide salt is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, and even more preferably 1 mass% or more, based on the total mass of the negative electrode material. From the viewpoint of easily achieving both excellent life performance and excellent discharge performance, the total content of the chloride salt, the bromide salt, and the iodide salt is preferably 20 mass% or less, more preferably 15 mass% or less, and even more preferably 10 mass% or less, based on the total mass of the negative electrode material.

[0032] The negative electrode material may contain additives other than the negative electrode active material and the above-mentioned halide salt. Examples of the additives include a binder and a conductive agent. Examples of the binder include polytetrafluoroethylene, hydroxyethyl cellulose, polyethylene oxide, polyethylene, and polypropylene. The content of the binder may be, for example, 0.5 to 10 parts by mass relative to 100 parts by mass of the negative electrode active material. Examples of the conductive agent include an indium compound (such as indium oxide). The content of the conductive agent may be, for example, 1 to 20 parts by mass relative to 100 parts by mass of the negative electrode active material.

[0033] According to the negative electrode of the present embodiment described above, a zinc battery having excellent cycle life performance can be obtained. The reason why such an effect is obtained is not clear, but the present inventors speculate as follows. First, in a zinc battery, a zinc passive film is formed on the surface of the negative electrode (zinc electrode) as the battery reaction proceeds. It is considered that this passive film is one of the factors that deteriorate the cycle life performance, but when the negative electrode material contains at least one halide salt selected from the group consisting of chloride salts, bromide salts, and iodide salts, the above passive film is corroded by the halide salt in the negative electrode material or the halide salt dissolves in the electrolyte, resulting in halide ions (at least one ion selected from the group consisting of chloride ions, bromide ions, and iodide ions), and therefore it is considered that the thickening of the passive film is suppressed. As a result, it is speculated that in a zinc battery using the negative electrode of the present embodiment, the deterioration of cycle life performance caused by the passive film is suppressed, and excellent cycle life performance can be obtained.

[0034] The negative electrode of this embodiment can be obtained, for example, by adding a solvent (e.g., water) to a raw material for the negative electrode material, kneading the mixture to obtain a negative electrode material paste (a paste-like negative electrode material), and then forming a negative electrode material layer using the negative electrode material paste. Examples of the raw material for the negative electrode material include raw materials for the negative electrode active material (e.g., metallic zinc, zinc oxide, and zinc hydroxide), at least one halide salt selected from the group consisting of chloride salts, bromide salts, and iodide salts, and other additives (e.g., the indium compound and the binder).

[0035] As a method for forming the negative electrode material layer, for example, a method in which a negative electrode material paste is applied or filled onto a current collector and then dried to obtain a negative electrode material layer can be mentioned. The density of the negative electrode material layer may be increased by pressing or the like, if necessary.

[0036] The negative electrode obtained by the above method is an unformed negative electrode, but as described below, a formed negative electrode may be obtained by forming the negative electrode after assembling a zinc battery.

[0037] Hereinafter, a nickel-zinc battery will be described as an example of a zinc battery in which the negative electrode of the above embodiment is used.

[0038] The zinc battery of one embodiment includes a battery case, and an electrode group (e.g., an electrode plate group) and an electrolyte solution housed in the battery case. The zinc battery of one embodiment may be either formed or unformed.

[0039] The electrode group includes, for example, a positive electrode (for example, a positive electrode plate), a negative electrode (for example, a negative electrode plate), and a separator. The positive electrode and the negative electrode are adjacent to each other via one or more separators. That is, one or more separators are provided between adjacent positive electrodes and negative electrodes. The electrode group may include a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators. When the electrode group includes a plurality of negative electrodes, at least one of the plurality of negative electrodes is the negative electrode of the above embodiment, and preferably, all of the negative electrodes are the negative electrodes of the above embodiment. When the electrode group includes a plurality of positive electrodes and / or a plurality of negative electrodes, the positive electrodes and the negative electrodes may be alternately stacked via separators. The plurality of positive electrodes and the plurality of negative electrodes may be connected to each other, for example, by straps.

[0040] The positive electrode includes, for example, a positive electrode current collector and a positive electrode material supported on the positive electrode current collector.

[0041] The positive electrode current collector constitutes a conductive path for the current from the positive electrode material. The positive electrode current collector has, for example, a flat plate shape, a sheet shape, or the like. The positive electrode current collector may be a three-dimensional mesh-structured current collector constituted by foam metal, expanded metal, punching metal, felt-like material of metal fiber, or the like. The positive electrode current collector is constituted by a material having electrical conductivity and alkali resistance. For example, a material that is stable even at the reaction potential of the positive electrode (a material having an oxidation-reduction potential more noble than the reaction potential of the positive electrode, a material that forms a protective film such as an oxide film on the substrate surface in an alkaline aqueous solution to stabilize it, etc.) can be used as such a material. In addition, in the positive electrode, a decomposition reaction of the electrolyte proceeds as a side reaction, generating oxygen gas, and a material with a high oxygen overvoltage is preferable in that it can suppress the progress of such a side reaction. Specific examples of materials that constitute the positive electrode current collector include platinum; nickel; and metal materials (copper, brass, steel, etc.) plated with metals such as nickel.

[0042] The positive electrode material may be in a layered form (positive electrode material layer). For example, a positive electrode material layer may be formed on a positive electrode current collector, and when 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 current collector.

[0043] The positive electrode material contains a positive electrode active material. Examples of the positive electrode active material include nickel oxyhydroxide (NiOOH) and nickel hydroxide. The positive electrode material contains, for example, nickel oxyhydroxide in a fully charged state and nickel hydroxide in an end-of-discharge state. The content of the positive electrode active material may be, for example, 50 to 95 mass% based on the total mass of the positive electrode material.

[0044] The positive electrode material may contain additives. Examples of additives include binders, conductive agents, and expansion inhibitors. Examples of binders include hydrophilic or hydrophobic polymers, such as hydroxypropylmethylcellulose (HPMC), carboxymethylcellulose (CMC), sodium polyacrylate (SPA), and fluorine-based polymers (polytetrafluoroethylene (PTFE)). The content of the binder may be, for example, 0.01 to 5 parts by mass relative to 100 parts by mass of the positive electrode active material. Examples of conductive agents include cobalt compounds (metallic cobalt, cobalt oxide, cobalt hydroxide, etc.). The content of the conductive agent may be, for example, 1 to 20 parts by mass relative to 100 parts by mass of the positive electrode active material. Examples of expansion inhibitors include zinc oxide. The content of the expansion inhibitor may be, for example, 0.01 to 5 parts by mass relative to 100 parts by mass of the positive electrode active material.

[0045] The separator may be, for example, a separator having a shape such as a flat plate or a sheet. Examples of the separator include a polyolefin-based microporous membrane, a nylon-based microporous membrane, an oxidation-resistant ion-exchange resin membrane, a cellophane-based regenerated resin membrane, an inorganic-organic separator, and a polyolefin-based nonwoven fabric. The separator may be processed into a bag shape so that the positive electrode and / or the negative electrode can be accommodated. In this case, the positive electrode and / or the negative electrode may be accommodated in the separator. The separator may be used alone or in combination of two or more types.

[0046] The electrolytic solution contains, for example, a solvent and an electrolyte. Examples of the solvent include water (e.g., ion-exchanged water). Examples of the electrolyte include a basic compound. Examples of the basic compound include alkali metal hydroxides such as potassium hydroxide (KOH), sodium hydroxide (NaOH), and lithium hydroxide (LiOH). The electrolytic solution may further contain, as an electrolyte, potassium phosphate (K3PO4), potassium fluoride (KF), potassium carbonate (K2CO3), sodium phosphate (Na3PO4), sodium fluoride (NaF), and may further contain an indium compound such as indium oxide, zinc oxide, antimony oxide, titanium dioxide, a surfactant, and the like.

[0047] The manufacturing method of the nickel-zinc battery described above includes, for example, a component manufacturing process for obtaining components of a zinc battery, and an assembly process for assembling the components to obtain a zinc battery.

[0048] In the component manufacturing process, an unformed negative electrode and an unformed positive electrode may be obtained in the same manner as in the above-mentioned negative electrode manufacturing method. The unformed positive electrode can be obtained, for example, by adding a solvent (e.g., water) to a raw material for a positive electrode material and kneading the mixture to obtain a positive electrode material paste (a paste-like positive electrode material), and then forming a positive electrode material layer using the positive electrode material paste (for example, applying or filling the positive electrode material paste on a positive electrode current collector and then drying the paste). The density of the positive electrode material layer may be increased by pressing or the like, as necessary. Examples of raw materials for the positive electrode material include raw materials for a positive electrode active material (e.g., nickel hydroxide), additives (e.g., the binder), and the like.

[0049] In the assembly process, for example, the positive and negative electrodes obtained in the component manufacturing process are alternately stacked with separators between them, and then the positive and negative electrodes are connected to each other 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).

[0050] Next, the electrolyte is poured into the battery case of the unformed zinc battery and left for a certain period of time. Then, the zinc battery (nickel-zinc battery) is obtained by forming the battery by charging under predetermined conditions. The forming conditions can be adjusted according to the properties of the electrode active materials (positive and negative active materials).

[0051] The above describes an example of a nickel-zinc battery (e.g., a nickel-zinc secondary battery) in which the positive electrode is a nickel electrode, but the zinc battery may also be an air-zinc battery (e.g., an air-zinc secondary battery) in which the positive electrode is an air electrode, or a silver-zinc battery (e.g., a silver-zinc secondary battery) in which the positive electrode is a silver oxide electrode.

[0052] The air electrode of the air zinc battery can be a known air electrode used in air zinc batteries. The air electrode includes, for example, an air electrode catalyst, an electron conductive material, etc. The air electrode catalyst can be an air electrode catalyst that also functions as an electron conductive material.

[0053] As the air electrode catalyst, one that functions as a positive electrode in an air zinc battery can be used, and various air electrode catalysts that can utilize oxygen as a positive electrode active material can be used. Examples of the air electrode catalyst include carbon-based materials (graphite, etc.) having an oxidation-reduction catalytic function, metal materials (platinum, nickel, etc.) having an oxidation-reduction catalytic function, and inorganic oxide materials (perovskite-type oxides, manganese dioxide, nickel oxide, cobalt oxide, spinel oxide, etc.) having an oxidation-reduction catalytic function. The shape of the air electrode catalyst is not particularly limited, and may be, for example, particulate. The amount of the air electrode catalyst used in the air electrode may be 5 to 70 volume % relative to the total volume of the air electrode, 5 to 60 volume %, or 5 to 50 volume %.

[0054] As the electron conductive material, a material that has electrical conductivity and enables electron conduction between the air electrode catalyst and the separator can be used. 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 fibers and metal fibers; metal powders such as copper, silver, nickel, and aluminum; organic electron conductive materials such as polyphenylene derivatives; and any mixtures thereof. The shape of the electron conductive material may be particulate or may be other shapes. The electron conductive material is preferably used in a form that provides a continuous phase in the thickness direction in the air electrode. For example, the electron conductive material may be a porous material. The electron conductive material may also be in the form of a mixture or complex with the air electrode catalyst, and may be an air electrode catalyst that also functions as an electron conductive material as described above. The amount of the electronically conductive material used in the air electrode may be 10 to 80% by volume, 15 to 80% by volume, or 20 to 80% by volume relative to the total amount of the air electrode.

[0055] As the silver oxide electrode of the silver-zinc battery, a known silver oxide electrode used in silver-zinc batteries can be used. The silver oxide electrode includes, for example, silver(I) oxide. EXAMPLES

[0056] The present invention will be described in detail below with reference to examples, although the present invention is not limited to the following examples.

[0057] <Example 1> [Preparation of positive electrode] A lattice body made of foamed nickel with a porosity of 95% was prepared, and the lattice body was pressure-molded to obtain a positive electrode current collector. Next, a predetermined amount of cobalt-coated nickel hydroxide powder, metal cobalt, cobalt hydroxide, yttrium oxide, CMC (carboxymethylcellulose), PTFE (polytetrafluoroethylene), and ion-exchanged water were weighed and mixed, and the mixture was stirred to prepare a positive electrode material paste. At this time, the mass ratio of the solid content was adjusted to "nickel hydroxide: metal cobalt: yttrium oxide: cobalt hydroxide: CMC: PTFE = 88: 10.3: 1: 0.3: 0.3: 0.1". The moisture content of the positive electrode material paste was adjusted to 27.5 mass% based on the total mass of the positive electrode material paste. Next, the positive electrode material paste was applied to the positive electrode material support part of the positive electrode current collector, and then dried at 80 ° C. for 30 minutes. After that, pressure molding was performed with a roll press to obtain an unformed positive electrode having a positive electrode material layer.

[0058] [Preparation of negative electrode] A tin-plated copper plate punching metal with a porosity of 55% was prepared as a negative electrode current collector. Then, zinc oxide, metal zinc, HEC (hydroxyethyl cellulose), and additives shown in Table 1 below were weighed so that the mass ratio of the solid content was the value shown in Table 1, mixed with a predetermined amount of ion-exchanged water, and the resulting mixture was stirred to prepare a negative electrode material paste. AV-15F (product name) manufactured by Sumitomo Seika Chemicals Co., Ltd. was used as the HEC. The moisture content of the negative electrode material paste was adjusted to 32.5 mass% based on the total mass of the negative electrode material paste. Next, the negative electrode material paste was applied onto the negative electrode current collector and dried at 80°C for 30 minutes. Thereafter, pressure molding was performed using a roll press to obtain an unformed negative electrode (negative electrode 1) having a negative electrode material (negative electrode layer).

[0059] [Preparing the separator] For the separator, UP3355 (manufactured by Ube Industries, Ltd., product name, air permeability: 440 sec / 100 mL) was used as the microporous membrane, and nonwoven fabric (manufactured by Nippon Kodoshi Kogyo Co., Ltd., product name: VL-100, air permeability: 0.3 sec / 100 mL) was used as the nonwoven fabric. The microporous membrane was hydrophilized with a surfactant Triton-X100 (manufactured by Sigma-Aldrich Japan LLC) before the battery was assembled. The hydrophilization was performed by immersing the microporous membrane in an aqueous solution containing 1% by mass of Triton-X100 for 24 hours, and then drying at room temperature for 1 hour. The air permeability of the microporous membrane indicates the value after the hydrophilization. Furthermore, the microporous membrane was cut to a predetermined size, folded in half, and processed into a bag shape by heat welding the sides. The nonwoven fabric was cut to a predetermined size.

[0060] [Construction of nickel-zinc battery] A positive electrode (unformed positive electrode) and a negative electrode (unformed negative electrode) were housed in a microporous membrane processed into a bag shape. After laminating the positive electrode housed in the microporous membrane in a bag shape, the negative electrode housed in the microporous membrane in a bag shape, and nonwoven fabric, the electrode plates of the same polarity were connected with a strap to prepare an electrode group (electrode plate group). The electrode group was configured with two positive electrodes and three negative electrodes, with one nonwoven fabric placed between each of the positive and negative electrodes (between the microporous membrane on the positive electrode side and the microporous membrane on the negative electrode side). After placing this electrode group in a battery case, a lid was attached to the top of the battery case, and an electrolyte was poured into the battery case to obtain an unformed nickel-zinc battery. Thereafter, charging was performed under conditions of 32 mA and 15 hours to prepare a nickel-zinc battery with a nominal capacity of 320 mAh. As the electrolyte, a 30 mass % aqueous solution of potassium hydroxide containing 1 mass % lithium hydroxide was used.

[0061] <Examples 2 to 6 and Comparative Example 1> Negative electrodes 2 to 7 were produced in the same manner as in Example 1, except that the additives used in producing the negative electrodes were changed to those shown in Table 1. Next, nickel-zinc batteries of Examples 2 to 6 and Comparative Example 1 were produced in the same manner as in Example 1, except that negative electrodes 2 to 7 were used, respectively.

[0062] [Table 1]

[0063] <Characteristics evaluation> The cycle life performance of the nickel-zinc batteries was evaluated using the nickel-zinc batteries of Examples 1 to 6 and Comparative Example 1. The specific evaluation method is shown below, and the results are shown in Table 2.

[0064] [Cycle life performance evaluation] The test consisted of charging the nickel-zinc battery at 25°C, 320mA (1C), and a constant voltage of 1.9V until the current value decayed to 16mA (0.05C), and then discharging the nickel-zinc battery at a constant current of 1280mA (4C) until the battery voltage reached 1.1V (one cycle). The test was terminated when the discharge capacity fell below 80% of the discharge capacity of the first cycle, and the cycle life performance was evaluated based on the number of cycles performed until the end of the test.

[0065] [Table 2]

Claims

1. A current collector and a negative electrode material supported on the current collector, The negative electrode material contains a negative electrode active material containing zinc and at least one halide salt selected from the group consisting of chloride salts, bromide salts, and iodide salts, 13. A negative electrode for a zinc secondary battery, wherein the halide salt is an ammonium halide.

2. 10. The anode of claim 1, wherein the anode material comprises ammonium chloride.

3. 10. The anode of claim 1, wherein the anode material comprises ammonium bromide.

4. 10. The anode of claim 1, wherein the anode material comprises ammonium iodide.

5. A current collector and a negative electrode material supported on the current collector, The negative electrode material contains a negative electrode active material containing zinc and an iodide salt, The negative electrode for a zinc secondary battery, wherein the iodide salt is at least one selected from the group consisting of alkali metal iodides and ammonium iodide.

6. The negative electrode according to any one of claims 1 to 5, which is for a nickel-zinc secondary battery.

7. A zinc secondary battery comprising the negative electrode according to any one of claims 1 to 6.

8. A current collector and a negative electrode material supported on the current collector, The negative electrode material contains a negative electrode active material containing zinc and a bromide salt, The negative electrode for a nickel-zinc secondary battery, wherein the bromide salt is at least one selected from the group consisting of alkali metal bromides and ammonium bromide.

9. A current collector and a negative electrode material supported on the current collector, The negative electrode material contains a negative electrode active material containing zinc and at least one halide salt selected from the group consisting of chloride salts, bromide salts, and iodide salts, The negative electrode for a nickel-zinc secondary battery, wherein the halide salt is at least one selected from the group consisting of alkali metal halides and ammonium halides.

10. 10. The anode of claim 9, wherein the anode material comprises a chloride salt.

11. A nickel-zinc secondary battery comprising the negative electrode according to any one of claims 8 to 10.

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