Alkali storage battery

Abstract

The alkali storage battery includes a positive electrode. The positive electrode includes a positive electrode mixture. The positive electrode mixture contains a nickel compound and a metal compound as positive electrode active materials. The metal compound is a compound of at least one metal element selected from the group consisting of titanium, niobium, tungsten, vanadium, molybdenum, zirconium, and tantalum. The ratio (Wm / Wn) of the mass (Wm) of the metal compound contained in the positive electrode mixture to the mass (Wn) obtained by converting the nickel compound contained in the positive electrode mixture into nickel hydroxide is in the range of 0.2 / 100 to 5.0 / 100. The metal compound contains iron in an amount of 10 to 10,000 ppm (mass ratio). The ratio (We / Wp) of the mass (We) of the alkali electrolyte solution to the mass (Wp) of the positive electrode mixture is within the range of 0.35-1.0.

Description

Technical Field

[0001] The present application relates to an alkaline storage battery. Background Art

[0002] Alkaline storage batteries such as nickel-metal hydride storage batteries are used in various applications. Various proposals have been made regarding alkaline storage batteries.

[0003] Patent document 1 (Japanese Patent Application Laid-Open No. 10-40948) discloses "a charging characteristics improver, characterized in that it is a charging characteristics improver for improving the charging characteristics of an alkaline battery, and the charging characteristics improver has one or more oxides or hydroxides selected from Sr, Sc, lanthanoids, Al, Ga, Ti, Zr, Nb, Bi and Ir."

[0004] Patent document 2 (Japanese Patent No. 4474722 specification) discloses "a positive electrode for an alkaline storage battery, comprising nickel hydroxide solid solution particles and a single substance of a rare earth element or a compound thereof containing Fe or an Fe compound, wherein the content of the single substance of the rare earth element or the compound thereof is 0.1 to 10% by weight relative to the nickel hydroxide solid solution particles, and the content of the Fe or the Fe compound is 0.1 to 100 ppm relative to the single substance of the rare earth element or the compound thereof."

[0005] Patent document 3 (Japanese Patent Publication No. 2002-298840) discloses "a positive electrode active material for an alkaline storage battery, characterized in that it comprises solid solution particles having nickel hydroxide as a main component, 1% to 30% of the surface area of ​​the solid solution particles is covered with oxide particles of at least one selected from yttrium, scandium or lanthanide elements, and the periphery thereof is covered with cobalt oxide having an average valence of cobalt greater than 3.0."

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 10-40948

[0009] Patent Document 2: Japanese Patent No. 4474722

[0010] Patent Document 3: Japanese Patent Application Publication No. 2002-298840 Summary of the invention

[0011] Alkaline storage batteries are used in a variety of situations, and therefore, there is a demand for alkaline storage batteries that show little degradation in battery characteristics even when used in environments with a variety of temperatures.

[0012] One aspect of the present application relates to an alkaline storage battery. The alkaline storage battery includes a positive electrode, a negative electrode, a separator, and an alkaline electrolyte. The positive electrode includes a positive electrode collector and a positive electrode mixture supported by the positive electrode collector. The positive electrode mixture includes a nickel compound as a positive electrode active material and a metal compound. The metal compound is a compound of at least one metal element selected from titanium, niobium, tungsten, vanadium, molybdenum, zirconium, and tantalum. The ratio Wm / Wn of the mass Wm of the metal compound contained in the positive electrode mixture to the mass Wn of the nickel compound contained in the positive electrode mixture converted into nickel hydroxide is in the range of 0.2 / 100 to 5.0 / 100. The metal compound contains iron in the range of 10 to 10000 ppm (mass ratio). The ratio We / Wp of the mass We of the alkaline electrolyte to the mass Wp of the positive electrode mixture is in the range of 0.35 to 1.0.

[0013] As long as they can be combined, the matters described in two or more claims arbitrarily selected from a plurality of claims described in the scope of the appended claims may be combined. In addition, as long as they can be combined, the configurations described in the embodiments may be arbitrarily combined.

[0014] According to the present application, it is possible to obtain an alkaline storage battery in which degradation of battery characteristics is minimal even when used in a low-temperature environment or a high-temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a partially exploded perspective view schematically showing the alkaline storage battery according to the first embodiment.

[0016] Figure 2 It is schematically indicated Figure 1 An enlarged cross-sectional view of an electrode group of an alkaline storage battery is shown. DETAILED DESCRIPTION

[0017] Hereinafter, the embodiments of the present application will be described with examples, but the present application is not limited to the examples described below. In the following description, specific numerical values ​​and materials are sometimes exemplified, but other numerical values ​​and other materials may also be applied as long as the invention of the present application can be implemented. In this specification, a record such as "numerical value A to numerical value B" includes numerical value A and numerical value B, and can be rewritten as "above numerical value A and below numerical value B". In the following description, when the lower limit and upper limit of numerical values ​​related to specific physical properties, conditions, etc. are exemplified, as long as the lower limit is not above the upper limit, any of the exemplified lower limits can be arbitrarily combined with any of the exemplified upper limits.

[0018] (Alkaline batteries)

[0019] The alkaline storage battery of the present embodiment is sometimes referred to as "alkaline storage battery (A)" hereinafter. The alkaline storage battery (A) includes a positive electrode, a negative electrode, a separator, and an alkaline electrolyte. The positive electrode includes a positive electrode collector and a positive electrode mixture supported by the positive electrode collector. The positive electrode mixture includes a nickel compound and a metal compound as positive electrode active materials. The metal compound is sometimes referred to as "metal compound (M)" hereinafter. The metal compound (M) is a compound of at least one metal element selected from titanium (Ti), niobium (Nb), tungsten (W), vanadium (V), molybdenum (Mo), zirconium (Zr), and tantalum (Ta).

[0020] The alkaline storage battery (A) satisfies the following conditions (1) to (3).

[0021] (1) The ratio Wm / Wn of the mass Wm of the metal compound (M) contained in the positive electrode mixture to the mass Wn of the nickel compound (positive electrode active material) contained in the positive electrode mixture converted into nickel hydroxide is in the range of 0.2 / 100 to 5.0 / 100.

[0022] (2) The metal compound (M) contains iron (Fe) in a range of 10 to 10,000 ppm (mass ratio).

[0023] (3) The ratio We / Wp of the mass We of the alkaline electrolyte contained in the battery to the mass Wp of the positive electrode mixture contained in the battery is in the range of 0.35 to 1.0.

[0024] As shown in the examples, according to the alkaline storage battery (A), even when trickle charging at high temperature and trickle charging at low temperature are repeated, an increase in battery resistance can be suppressed.

[0025] Patent Documents 1 to 3 disclose technologies using additives containing rare earth elements. Patent Document 1 states that by using additives containing rare earth elements, oxygen generation during high-temperature charging can be suppressed. However, the inventors have found that even if additives containing rare earth elements are used, the battery characteristics will be greatly reduced if trickle charging at high temperatures and trickle charging at low temperatures are repeated. The reason for this is not clear at present, but one of the reasons is that if trickle charging is performed at low temperatures, γ-nickel hydroxide is generated, making the positive electrode easy to swell. If the positive electrode swells, the amount of electrolyte contained in the positive electrode increases, thereby increasing the resistance of the battery and reducing the battery characteristics.

[0026] As a result of the research, the present inventors have recently found that the above-mentioned configuration of the alkaline storage battery (A) can suppress an increase in battery resistance even when trickle charging at high temperature and trickle charging at low temperature are repeated. The present application is based on this new finding.

[0027] Even when the alkaline storage battery (A) is charged and discharged at high or low temperatures, the battery characteristics are only slightly degraded. Therefore, the alkaline storage battery (A) can be used for various purposes in various environments. The alkaline storage battery (A) is preferably used as a backup power source or an emergency power source.

[0028] The metal compound (M) may be a compound other than a hydroxide and an oxide, but a hydroxide and an oxide are preferably used. The positive electrode mixture may contain only one metal compound (M) or may contain a plurality of metal compounds.

[0029] Examples of metal compounds (M) containing titanium include TiO2, TiO2·nH2O (metatitanic acid), etc. The crystal form of TiO2 may be either rutile or anatase, but anatase titanium oxide is more preferred. Examples of metal compounds (M) containing niobium include Nb2O3, etc. Examples of metal compounds (M) containing tungsten include WO3, etc., and examples of metal compounds (M) containing vanadium include V2O5, etc. Examples of metal compounds (M) containing molybdenum include MoO3, etc., examples of metal compounds (M) containing zirconium include ZrO2, etc., and examples of metal compounds (M) containing tantalum include Ta2O5, etc. As described above, examples of metal compounds (M) include titanium oxide, niobium oxide, tungsten oxide, vanadium oxide, molybdenum oxide, zirconium oxide, and tantalum oxide. The metal compound (M) may be a compound containing titanium and / or a compound containing niobium, or may be an oxide of titanium and / or an oxide of niobium.

[0030] As shown in the above condition (1), the ratio Wm / Wn is in the range of 0.2 / 100 to 5.0 / 100. If the value of the ratio Wm / Wn is multiplied by 100 times, it is the ratio (%) of the mass Wm of the metal compound (M) contained in the positive electrode mixture to the mass Wn obtained by converting the nickel compound contained in the positive electrode mixture into nickel hydroxide (Ni(OH)2). Specifically, the ratio of mass Wm to mass Wn is in the range of 0.2% to 5.0%. It should be noted that the mass obtained by converting the nickel compound into nickel hydroxide is the mass converted assuming that the nickel compound is all nickel hydroxide, which can be obtained by dividing the mass of Ni atoms in the nickel compound by the molar mass of Ni and then multiplying it by the molar mass of nickel hydroxide. The mass of Ni atoms in the nickel compound can be obtained by analyzing the positive electrode mixture using ICP analysis, etc.

[0031] The ratio Wm / Wn is 0.2 / 100 or more, and may be 1.0 / 100 or more, or 2.0 / 100 or more. The ratio Wm / Wn is 5.0 / 100 or less, and may be 2.0 / 100 or less. The ratio Wm / Wn is in the range of 0.2 / 100 to 5.0 / 100, and may be in the range of 1.0 / 100 to 5.0 / 100, or 2.0 / 100 to 5.0 / 100. In these ranges, as long as the lower limit is not greater than the upper limit, the upper limit may be set to 2.0 / 100 or 1.0 / 100.

[0032] By adding the metal compound (M), the amount of oxygen generated in the positive electrode during charging at high temperature (e.g., trickle charging at high temperature) can be reduced. By reducing the amount of oxygen generated, the consumption of the electrolyte due to oxidation of the negative electrode can be suppressed, and as a result, the increase in the internal resistance of the battery can be suppressed. By setting the ratio Wm / Wn to 0.2 / 100 or more, the effect of suppressing oxygen generation can be fully obtained. By setting the ratio Wm / Wn to 5.0 / 100 or less, the increase in resistance caused by the presence of a large amount of metal compounds (M) with low conductivity can be suppressed.

[0033] As shown in the above condition (2), the content (mass ratio) of iron contained in the metal compound (M) is 10 ppm or more, and may be 100 ppm or more, or 1000 ppm or more. The content is 10000 ppm or less, and may be 1000 ppm or less, or 100 ppm or less. The content is in the range of 10 to 10000 ppm, and may be in the range of 100 to 10000 ppm, or 1000 to 10000 ppm. In these ranges, as long as the lower limit is not greater than the upper limit, the upper limit may be set to 1000 ppm or 100 ppm.

[0034] Oxygen generated in the positive electrode during overcharge squeezes part of the metal compound (M) out of the positive electrode and moves to the separator and the negative electrode. When the metal compound (M) is present in the positive electrode, the iron contained in the metal compound (M) does not dissolve due to the influence of the potential. However, if the metal compound (M) moves to the separator and the negative electrode, the iron contained in the metal compound (M) slowly dissolves and re-precipitates uniformly on the surface of the active material particles of the positive electrode. Due to the effect of the re-precipitated iron, the formation of γ-nickel oxyhydroxide is suppressed. As a result, the swelling of the positive electrode is suppressed, and the reduction of the electrolyte in the separator and the negative electrode is suppressed. Therefore, the increase in the internal resistance of the battery during charging (especially trickle charging) can be suppressed. By setting the content (mass ratio) of iron contained in the metal compound (M) to 10 ppm or more, a high effect can be obtained. By setting the content to 10000 ppm or less, the reduction in charging efficiency and corrosion of hydrogen storage alloys caused by excessive iron can be suppressed.

[0035] As shown in the above condition (3), the ratio We / Wp of the mass We of the alkaline electrolyte contained in the battery to the mass Wp of the positive electrode mixture contained in the battery is 0.35 or more, and may be 0.50 or more, 0.60 or more, or 0.70 or more. The ratio We / Wp is 1.0 or less, and may be 0.70 or less, 0.60 or less, or 0.50 or less. The ratio We / Wp is in the range of 0.35 to 1.0, and may be in the range of 0.50 to 1.0, 0.60 to 1.0, or 0.70 to 1.0. In these ranges, as long as the lower limit is not greater than the upper limit, the upper limit may be set to 0.70, 0.60, or 0.50. The mass We of the electrolyte may also be obtained from the mass difference before and after the electrolyte is removed when the battery is disassembled and the electrolyte is removed by washing with water and drying. The mass Wp of the positive electrode mixture can be obtained from the mass difference before and after dissolution when the positive electrode plate is dissolved with a weak acid such as acetic acid so as to leave the foamed nickel porous body.

[0036] By setting the ratio We / Wp to 0.35 or more, the movement of the metal compound (M) caused by oxygen generated in the positive electrode can be promoted. As a result, the above-mentioned effect can be easily obtained. By setting the ratio We / Wp to 1.0 or less, the leakage of the electrolyte from the outer packaging (battery case) due to excessive electrolyte can be suppressed.

[0037] The proportion of the positive electrode active material (nickel compound) in the positive electrode mixture may be 80% by mass or more, or 90% by mass or more.

[0038] In the alkaline storage battery (A), the positive electrode, the negative electrode, and the separator may constitute a wound body. An example of this case has the following structures (4) to (6).

[0039] (4) In the wound body, the outermost periphery of the negative electrode exists outside the outermost periphery of the positive electrode.

[0040] (5) The negative electrode includes a negative electrode current collector and a negative electrode mixture layer disposed on the negative electrode current collector. The negative electrode mixture layer includes a hydrogen storage alloy.

[0041] (6) The mass Mout of the hydrogen storage alloy per unit area of ​​the outermost circumference (the outermost circumference) of the negative electrode in the wound body is smaller than the mass Min of the hydrogen storage alloy per unit area of ​​the portion other than the outermost circumference. The mass Mout and the mass Min can be set, for example, per 1 cm 2 The quality of the.

[0042] The effect of the present application can be obtained by moving a portion of the metal compound (M) from the positive electrode due to the oxygen generated in the positive electrode. In order to uniformly generate oxygen in the positive electrode throughout the positive electrode, it is desired that the mass per unit area of ​​the negative electrode active material at a position facing the positive electrode is uniform regardless of the position of the winding body. It should be noted that the mass of the negative electrode active material (such as a hydrogen storage alloy) per unit area in the negative electrode means the mass of the negative electrode active material present on both sides when there are negative electrode mixture layers on both sides of the negative electrode collector. For example, consider a case where A grams of negative electrode active material are present on one side of a negative electrode collector having a length of 1 cm and a width of 1 cm, and B grams of negative electrode active material are present on the other side. In this case, the negative electrode of this part has a mass per 1 cm 2 The mass of the negative electrode active material is (A+B) grams.

[0043] The positive electrode mixture layer and the negative electrode mixture layer are configured to face each other at an appropriate mass ratio. However, in the case where the outermost periphery of the negative electrode exists outside the outermost periphery of the positive electrode, the mass per unit area of ​​the negative electrode active material that usually exists at the outermost periphery of the negative electrode is greater than the amount suitable for the positive electrode mixture layer. Therefore, in the case of a general alkaline storage battery, it is difficult to generate oxygen in the positive electrode uniformly throughout the positive electrode. In contrast, by adopting the above-mentioned (6) structure, oxygen generation in the positive electrode can occur more uniformly throughout the positive electrode.

[0044] The ratio Mout / Min of the mass Mout of the hydrogen storage alloy per unit area of ​​the outermost circumference of the negative electrode to the mass Min of the hydrogen storage alloy per unit area of ​​the portion other than the outermost circumference may be 0.9 or less, 0.8 or less, or 0.6 or less. The ratio Mout / Min may be 0.3 or more, or 0.4 or more.

[0045] In order to realize the above-mentioned structure (6), the following structures (7) and / or (8) may be adopted. The alkaline storage battery (A) including the above-mentioned winding body may have the above-mentioned structures (4) to (6) and the following structures (7) and / or (8). Alternatively, the alkaline storage battery (A) including the above-mentioned winding body may have the above-mentioned structures (4) and (5) and the following structure (8). In this case, a favorable effect can also be obtained.

[0046] (7) The thickness D1 of the negative electrode mixture layer at the outermost periphery of the negative electrode is smaller than the thickness D0 of the negative electrode mixture layer present on the inner side with respect to the outermost periphery of the negative electrode.

[0047] (8) The thickness Dout of the portion of the negative electrode mixture layer disposed on the outer side (outer side) of the negative electrode current collector at the outermost periphery of the negative electrode is smaller than the thickness Din of the portion of the negative electrode mixture layer disposed on the inner side (inner side) of the negative electrode current collector at the outermost periphery of the negative electrode. That is, at the outermost periphery of the negative electrode, the thickness Dout of the portion of the negative electrode mixture layer disposed on the outer side of the negative electrode current collector may be smaller than the thickness Din of the portion of the negative electrode mixture layer disposed in the portion other than the outermost periphery.

[0048] Regarding the above configuration (7), the ratio D0 / D1 of the thickness D0 to the thickness D1 may be 0.9 or less, 0.8 or less, or 0.6 or less. The ratio D0 / D1 may be 0.3 or more, or 0.4 or more.

[0049] Regarding the above-mentioned configuration (8), the ratio Dout / Din of the thickness Dout of the portion of the negative electrode mixture layer disposed on the outer side of the negative electrode current collector at the outermost periphery of the negative electrode to the thickness Din of the portion of the negative electrode mixture layer disposed on the inner side of the negative electrode current collector at the outermost periphery of the negative electrode may be 0.9 or less, 0.5 or less, or 0.3 or less, or 0. The ratio D0 / D1 may be 0 or more, 0.2 or more, or 0.4 or more.

[0050] It should be noted that, regarding each thickness D0, thickness D1, thickness Dout, and thickness Din, when the thickness is not constant but varies depending on the location, the size relationship can be set to the size relationship of the average value, and the ratio can be set to the ratio of the average value. For example, the ratio D0 / D1 can be set to the ratio (average value of D0) / (average value of D1). Similarly, the ratio Dout / Din can be set to the ratio (average value of Dout) / (average value of Din). Here, the average value of the thickness D0 can be obtained by selecting 5 points in the corresponding part to measure the thickness and taking the arithmetic average of the thicknesses of the measured 5 points. The selected 5 points can be selected at equal intervals in the central part of the width direction of the corresponding part along the length direction (circumferential direction).

[0051] The alkaline electrolyte of the alkaline storage battery (A) may be an electrolyte in which sodium hydroxide is dissolved. In addition, the concentration of sodium hydroxide in the alkaline electrolyte may be higher than the concentration of potassium hydroxide in the alkaline electrolyte. In other words, the concentration of sodium ions in the alkaline electrolyte may be higher than the concentration of potassium ions in the alkaline electrolyte. Examples of electrolytes having this structure include: an alkaline electrolyte in which both sodium hydroxide and potassium hydroxide are dissolved and contained, and an alkaline electrolyte in which sodium hydroxide is dissolved and contained instead of potassium hydroxide. That is, examples of electrolytes having this structure include electrolytes in which the concentration of potassium hydroxide is zero.

[0052] When the alkaline storage battery (A) is charged in a high temperature environment, it is preferred to use sodium hydroxide as a solute. Therefore, when the alkaline storage battery (A) is charged in a high temperature environment, it is preferred to use an alkaline electrolyte having a higher sodium hydroxide concentration than a potassium hydroxide concentration.

[0053] (Method for producing metal compound (M))

[0054] The method for producing a metal compound (M) containing iron in a range of 10 to 10000 ppm (mass ratio) is not particularly limited. The metal compound (M) can be produced by dissolving iron in an aqueous solution of a material to be the metal compound (M), and introducing iron into particles of the metal compound (M) when the metal compound (M) is precipitated. The iron content in the metal compound (M) can be changed by controlling the concentration of iron ions in the aqueous solution.

[0055] As another method, an aqueous solution of a material to be the metal compound (M) and a solution in which iron is dissolved can be simultaneously dropped into an alkaline solution to introduce iron into the particles of the metal compound (M) when the metal compound (M) is precipitated. The iron content in the metal compound (M) can be changed by adjusting the concentration of iron ions in the aqueous solution and the dropping speed.

[0056] As another method, a powder of a material to be a metal compound (M) can be mixed with iron or an iron oxide, and then fired, and the resulting fired product can be pulverized to produce a metal compound (M) containing iron. The iron content in the metal compound (M) can be changed by adjusting the mixing ratio before firing.

[0057] The iron content in the metal compound (M) can also be adjusted by preparing a plurality of metal compounds (metal compounds (M)) having different iron contents and mixing these metal compounds.

[0058] (Manufacturing method of positive electrode)

[0059] The manufacturing method of the positive electrode is not limited, and the positive electrode can be manufactured by the same method as the known method. In one example of the manufacturing method, first, particles containing nickel compounds (particles of positive electrode active materials) and materials containing metal compounds (M) are mixed to prepare a positive electrode paste. Then, the positive electrode paste is applied or filled on the positive electrode collector and dried to form a positive electrode mixture (positive electrode mixture layer) supported by the positive electrode collector. At this time, the positive electrode mixture layer can be compressed (or rolled) as needed.

[0060] The form of the metal compound (M) when added to the positive electrode paste is not particularly limited. Typically, the metal compound (M) is added to the positive electrode paste in the form of particles.

[0061] The positive electrode paste generally contains a dispersion medium and, if necessary, further contains other components (conductive material, binder, thickener, etc.). As the dispersion medium, water, an organic medium, or a mixed medium obtained by mixing two or more liquid media selected from these can be used.

[0062] Examples of conductive materials and binders will be described later. As thickeners, for example, carboxymethyl cellulose and its modified products (including salts such as Na salts and ammonium salts), cellulose derivatives such as methyl cellulose; saponified polymers having vinyl acetate units such as polyvinyl alcohol; polyoxyalkylenes such as polyethylene oxide, etc. These thickeners can be used alone or in combination of two or more. The amount of the thickener can be 5 parts by mass or less relative to 100 parts by mass of the positive electrode active material, and can also be in the range of 0.01 to 3 parts by mass.

[0063] (Method for producing alkaline storage battery (A))

[0064] The manufacturing method of the alkaline storage battery (A) using the above-mentioned positive electrode is not particularly limited, and a known manufacturing method can be used. Specifically, first, an electrode group 15 is formed using a positive electrode, a negative electrode and a separator. Then, the electrode group and the electrolyte are contained in an outer packaging body. In this way, an alkaline storage battery can be manufactured.

[0065] The configuration and components of the alkaline storage battery (A) are described below. However, the configuration and components of the alkaline storage battery (A) are not limited to the following examples. Components other than the characteristic parts of the present application may also be known components.

[0066] The alkaline storage battery (A) comprises an outer package, an electrode group and an alkaline electrolyte contained in the outer package. The form of the electrode group is not limited, and it may be a wound body or a form other than a wound body (e.g., a laminate). The electrode group is formed by winding a positive electrode, a negative electrode, and a separator in a manner that a separator is arranged between the positive electrode and the negative electrode to form a wound body. The electrode group is formed by stacking a positive electrode, a negative electrode, and a separator in a manner that a separator is arranged between the positive electrode and the negative electrode to form a laminate.

[0067] (positive electrode)

[0068] The positive electrode includes a positive electrode current collector and a positive electrode mixture (positive electrode mixture layer) supported by the positive electrode current collector. The positive electrode may also be a paste-type positive electrode.

[0069] The positive electrode current collector is not particularly limited, and a known positive electrode current collector can be used. Examples of positive electrode current collectors include porous current collectors formed of metal (nickel or nickel alloy, etc.). Specifically, examples of positive electrode current collectors include nickel foam and sintered nickel plate, etc.

[0070] The positive electrode mixture contains particles of a nickel compound (positive electrode active material) and may contain other components (conductive material, binder, etc.) as required. The particles of the nickel compound may be particles of a known nickel compound (e.g., nickel hydroxide) used in alkaline storage batteries. A portion of the nickel hydroxide in the positive electrode mixture may be replaced by nickel oxyhydroxide.

[0071] The particles of the nickel compound may contain trace components other than nickel hydroxide and nickel oxyhydroxide. The surface of the particles of the nickel compound may be covered with other compounds. Examples of compounds used in such covering include metal hydroxides, etc. Specifically, examples of compounds used in covering include cobalt hydroxide, γ-cobalt oxyhydroxide, β-cobalt oxyhydroxide, etc. When the particles of the nickel compound are covered with other compounds, the mass Wn of the nickel compound contained in the positive electrode mixture does not include the mass of the other compounds.

[0072] The conductive material is not particularly limited, and known conductive materials can be used. Examples of conductive materials include graphites such as natural graphite (e.g., flaky graphite), artificial graphite, and expanded graphite; carbon black such as acetylene black and Ketjen black; conductive fibers such as carbon fibers and metal fibers; metal particles such as nickel powder and cobalt powder; organic conductive materials such as polyphenylene derivatives, etc. These conductive materials can be used alone or in combination of two or more. Conductive cobalt compounds (cobalt hydroxide, γ-type cobalt oxyhydroxide, etc.) can also be used as conductive materials.

[0073] The amount of the conductive material may be in the range of 0.01 to 20 parts by mass (eg, in the range of 0.1 to 10 parts by mass) relative to 100 parts by mass of the active material.

[0074] The conductive material can be added to the positive electrode paste and mixed with other ingredients. In addition, the surface of the active material particles can be pre-coated with a conductive material. The coating method using the conductive material is not limited, and a known method can be used. For example, the coating can be performed by coating the surface of the active material particles with a conductive material. Alternatively, the coating can be performed by attaching a dispersion containing a conductive material to the surface of the active material particles and then drying it. Alternatively, the coating can be performed using a mechanochemical method or the like.

[0075] The binder is not particularly limited, and known binders used in alkaline storage batteries can be used. Examples of binders include rubber-like materials such as styrene-butadiene copolymer rubber; polyolefin resins such as polyethylene and polypropylene; fluororesins such as polyvinylidene fluoride; acrylic resins such as ethylene-acrylic acid copolymers and ethylene-methyl acrylate copolymers, and Na ion crosslinked products thereof. These binders can be used alone or in combination of two or more. The amount of the binder can be 7 parts by mass or less relative to 100 parts by mass of the positive electrode active material, and can also be in the range of 0.01 to 5 parts by mass.

[0076] (negative electrode)

[0077] The negative electrode is not particularly limited and may be selected according to the type of the alkaline storage battery (A). As the negative electrode, a known negative electrode used as a negative electrode of an alkaline storage battery can be used.

[0078] The negative electrode may include a negative electrode current collector and a negative electrode mixture layer supported by the negative electrode current collector. The negative electrode current collector is not limited, and a known negative electrode current collector may be used. Examples of negative electrode current collectors include porous or non-porous metal (stainless steel, nickel, nickel alloy, etc.) sheets.

[0079] The negative electrode can be formed by attaching a negative electrode mixture containing a negative electrode active material to a negative electrode collector. The negative electrode mixture is usually used in the form of a paste containing a dispersion medium. In one example of a method for manufacturing a negative electrode, first, a negative electrode mixture paste containing a negative electrode active material is prepared. Then, the negative electrode paste is applied or filled onto the negative electrode collector, followed by drying and rolling. In this way, a negative electrode including a negative electrode collector and a negative electrode mixture layer supported by the negative electrode collector can be manufactured.

[0080] Examples of alkaline storage batteries (A) include nickel-metal hydride storage batteries and nickel-cadmium storage batteries. When the alkaline storage battery (A) is a nickel-metal hydride storage battery, a hydrogen storage alloy capable of electrochemically storing and releasing hydrogen can be used as the negative electrode active material. The hydrogen storage alloy is not particularly limited, and a known hydrogen storage alloy can be used. When the alkaline storage battery (A) is a nickel-cadmium storage battery, a cadmium compound (such as cadmium hydroxide) can be used as the negative electrode active material.

[0081] The negative electrode mixture may contain components other than the negative electrode active material (conductive agent, binder, thickener, etc.) as needed. The dispersion medium, conductive material, binder and thickener may use the same materials as those exemplified for the positive electrode. The amount of the conductive material, binder and thickener relative to 100 parts by mass of the negative electrode active material may be within the range exemplified as the amount relative to 100 parts by mass of the positive electrode active material.

[0082] (Alkaline electrolyte)

[0083] As the alkaline electrolyte, an aqueous solution containing an alkaline solute can be used. Examples of the solute include alkali metal hydroxides, specifically, lithium hydroxide, potassium hydroxide, sodium hydroxide, etc. The solute can be used alone or in combination of two or more.

[0084] The concentration of the solute (specifically, alkali metal hydroxide) contained in the alkaline electrolyte may be in the range of 2.5 to 13 mol / L (eg, 3 to 12 mol / L). The specific gravity of the alkaline electrolyte may be in the range of 1.1 to 1.6 (eg, 1.2 to 1.5).

[0085] The alkaline electrolyte preferably contains sodium hydroxide. The alkaline electrolyte may also contain sodium hydroxide and other alkali metal hydroxides (lithium hydroxide and / or potassium hydroxide). The alkaline electrolyte may also contain only sodium hydroxide as a solute.

[0086] The concentration of sodium hydroxide contained in the alkaline electrolyte can be in the range of 2.5 to 11.5 mol / L, preferably in the range of 3.5 to 10.5 mol / L (for example, in the range of 4 to 10 mol / L). When the concentration of sodium hydroxide is in this range (especially high concentration), the charging efficiency can be improved even when charging at high temperature. In addition, when the concentration of sodium hydroxide is in the above range (especially high concentration), the decrease in the average discharge voltage can be suppressed while maintaining high charging efficiency, and as a result, the cycle life can be improved.

[0087] (Spacer)

[0088] The separator is not particularly limited, and a known separator used in alkaline storage batteries can be used. Examples of the form of the separator include microporous films, nonwoven fabrics, and woven fabrics. The separator can be formed of an insulating material. Examples of the material of the separator include polyolefin resins such as polyethylene and polypropylene; fluororesins; polyamide resins, etc.

[0089] (other)

[0090] The components other than the above (external packaging, lead wires, etc.) are not particularly limited, and known components used in alkaline storage batteries can be used. When the alkaline storage battery (A) is a cylindrical battery, the external packaging in one example includes a cylindrical battery case with a bottom, a sealing body for sealing the battery case, and a gasket.

[0091] Hereinafter, an example of the present embodiment will be described in detail with reference to the accompanying drawings. The constituent elements of the embodiment of the example described below can be applied to the above-mentioned constituent elements. In addition, the constituent elements of the embodiment of the example described below can be changed based on the above-mentioned description. In addition, the matters described below can also be applied to the above-mentioned embodiment. In addition, in the embodiment of the example described below, constituent elements that are not necessary in the alkaline storage battery of the present application can be omitted.

[0092] (Implementation method 1)

[0093] The alkaline storage battery 10 of the first embodiment is shown in FIG. Figure 1 middle. Figure 11 is a partially exploded perspective view schematically showing the structure of an alkaline storage battery 10. The alkaline storage battery 10 includes a battery box 4 and an electrode group 15 and an alkaline electrolyte 17 housed in the battery box 4. The battery box 4 is a bottomed cylindrical box. The negative electrode 1, the positive electrode 2 and the separators 3 and 13 are in sheet form. The electrode group 15 is a winding body 16 formed by stacking the separators 3 and 13 between the negative electrode 1 and the positive electrode 2 and winding the negative electrode 1, the positive electrode 2 and the separators 3 and 13 around the central axis AX1. The opening of the battery box 4 is sealed with a sealing body 7 and an insulating gasket 8. The sealing body 7 includes a positive terminal 5 and a safety valve 6. The positive electrode 2 and the sealing body 7 are electrically connected via a positive electrode collector plate 9. The battery box 4 is electrically connected to the negative electrode 1 and acts as a negative terminal.

[0094] Figure 2 1 is an enlarged cross-sectional view schematically showing an electrode group 15 (wound body 16). The separators 3 and 13 are arranged in the wound body 16 to extend from the outside of the positive electrode 2 between the negative electrode 1 and the positive electrode 2 of the adjacent surrounding layers of the electrode group 15, and the positive electrode 2 that prevents direct contact between the negative electrode 1 and the positive electrode 2 includes a positive electrode collector 2A and a positive electrode mixture layer 2B arranged in the positive electrode collector 2A. The negative electrode 1 includes a negative electrode collector 1A and a negative electrode mixture layer 1B arranged on the negative electrode collector 1A. The alkaline storage battery 10 has the above-mentioned structure. The thickness D1 of the negative electrode mixture layer 1B at the outermost periphery of the negative electrode 1 can be smaller than the thickness D0 of the negative electrode mixture layer 1B existing on the inner side relative to the outermost periphery of the negative electrode 1. The negative electrode 1 may be wound as follows, that is, at the outermost periphery of the negative electrode 1, the negative electrode mixture layer 1B has a portion 12B disposed outside the negative electrode current collector 1A and a portion 11B disposed inside the negative electrode current collector 1A. The thickness Dout of the portion 12B of the negative electrode mixture layer 1B may be smaller than the thickness Din of the portion 11B of the negative electrode mixture layer 1B.

[0095] <Example>

[0096] The present application will be described in more detail below using examples. In the following examples, a plurality of nickel-metal hydride storage batteries were manufactured and evaluated.

[0097] (Experimental Example 1)

[0098] In Experimental Example 1, various nickel-metal hydride storage batteries were produced by changing the metal compound added to the positive electrode mixture. Specifically, the following steps were used to produce a nickel-metal hydride storage battery having the same Figure 1 The structure shown is similar to the structure of a battery.

[0099] (1) Preparation of positive electrode

[0100] The positive electrode paste was prepared by mixing nickel hydroxide particles covered with cobalt oxyhydroxide (100 parts by mass as nickel hydroxide), 1 part by mass of the metal compound shown in Table 1, 0.1 part by mass of carboxymethyl cellulose (thickener), and water. Then, the positive electrode paste was filled into a sheet of a foamed nickel porous body (positive electrode current collector 2A) and dried. The obtained sheet was compressed in the thickness direction and cut into a predetermined size (length: 80 mm, width: 43 mm), thereby producing a positive electrode 2. At this time, the metal compound was changed as shown in Table 1 to produce a variety of positive electrodes 2.

[0101] The following steps are used to prepare particles of nickel hydroxide covered with cobalt oxyhydroxide. First, 100 parts by mass of nickel hydroxide particles are mixed with an aqueous solution of cobalt sulfate to obtain a mixed solution. An aqueous ammonia solution and an aqueous sodium hydroxide solution are added dropwise to the mixed solution at a specified rate to cover the nickel hydroxide particles with cobalt hydroxide. The obtained particles are washed and dried, and then air-oxidized at 90° C. in the presence of an aqueous sodium hydroxide solution. In this way, particles of nickel hydroxide covered with cobalt oxyhydroxide are obtained.

[0102] The metal compound is prepared by the following steps. Titanium tetrachloride aqueous solution and iron (II) chloride aqueous solution are simultaneously added dropwise to sodium hydroxide aqueous solution for neutralization and hydrolysis, thereby preparing titanium oxide (TiO2) containing iron. Titanium oxide not containing iron is prepared by the same method as the above method except that the iron (II) chloride aqueous solution is not added. Ytterbium nitrate aqueous solution and iron (II) sulfate aqueous solution are simultaneously added dropwise to sodium hydroxide aqueous solution, thereby preparing ytterbium oxide containing iron. Ytterbium nitrate aqueous solution and iron (II) sulfate aqueous solution are simultaneously added dropwise to sodium hydroxide aqueous solution, thereby preparing yttrium oxide containing iron. The aqueous solution of the iron compound is added to the raw material solution in such a manner that the iron content in the metal compound is the value shown in Table 1. It should be noted that the metal compound can also be prepared multiple times, and the iron content of each metal compound can be analyzed by ICP analysis, etc., and the metal compounds can be mixed and used in such a manner as to achieve a specified amount of iron.

[0103] (2) Preparation of negative electrode

[0104] 100 parts by mass of LaNiCoMnAl-based hydrogen storage alloy, 0.2 parts by mass of carboxymethyl cellulose (thickener), 0.2 parts by mass of Ketjen black (conductive material), and 0.5 parts by mass of styrene butadiene rubber (binder) were mixed, and water was added to the obtained mixture and further mixed to prepare a negative electrode paste.

[0105] The negative electrode paste is applied to both surfaces of the negative electrode collector 1A to form a coating. The negative electrode collector 1A uses a punching metal made of iron that has been plated with nickel. After the obtained coating is dried, it is pressed together with the negative electrode collector 1A to form a negative electrode mixture layer 1B. The negative electrode mixture layer 1B is formed in a manner that makes the thickness substantially the same throughout the negative electrode 1. Then, the sheet consisting of the negative electrode collector 1A and the negative electrode mixture layer 1B is cut into a specified size (length: 130 mm, width: 43 mm), thereby obtaining the negative electrode 1.

[0106] (3) Production of alkaline batteries

[0107] The produced positive electrode 2 and negative electrode 1 and separators 3 and 13 are wound to produce a wound body 16 (electrode group 15). For the separators 3 and 13, nonwoven fabric made of sulfonated polypropylene is used.

[0108] Then, the wound body 16 and the alkaline electrolyte 17 are placed in the battery case 4. The alkaline electrolyte 17 uses an electrolyte with an alkali hydroxide concentration of 5.5 mol / L. As for the alkali hydroxide, KOH, NaOH, and LiOH are mixed at a molar ratio of KOH:NaOH:LiOH=2:7:1. 2 The alkaline electrolyte 17 is injected into the battery case 4 so that 20 mg of the electrolyte is contained in the apparent area of ​​.

[0109] Then, the opening of the battery case 4 was sealed with the gasket 8 and the sealing body 7. At this time, the foamed nickel porous body (positive electrode current collector 2A) and the sealing body 7 (positive electrode terminal 5) were electrically connected via a connecting member. In addition, the negative electrode 1 and the battery case 4 (negative electrode terminal) were electrically connected via a connecting member. In this way, a plurality of alkaline storage batteries (battery A1 and batteries C1 to C3) with different positive electrodes 2 were manufactured.

[0110] As described above, a plurality of AA-size alkaline storage batteries (nickel-metal hydride storage batteries) having a theoretical capacity of 1200 mAh were produced. The produced batteries were charged and discharged for activation, and then the following evaluations were performed.

[0111] (4) Charge and discharge test and evaluation

[0112] The battery prepared and activated by the above steps was subjected to a charge and discharge test. Specifically, the charging cycle of the following steps (a) and (b) was repeated for 25 cycles. It should be noted that It is a current value expressed in theoretical capacity / 1h, and It = 1200mA for the battery of the embodiment.

[0113] (a) Charging at 55°C with a current of 60 mA (0.05 It) for 160 hours.

[0114] (b) Charging at 0°C with a current of 60 mA (0.05 It) for 160 hours.

[0115] As described above, a charging test including high temperature trickle charge (charging under condition (a)) and low temperature trickle charge (charging under condition (b)) was performed. And, based on the initial battery resistance R0 before the charging test and the battery resistance R1 after the charging test, the life index X, which is the inverse of the resistance increase ratio, was calculated using the following formula.

[0116] Life index X = R0 / R1

[0117] Part of the manufacturing conditions of the battery and the evaluation results are shown in Table 1. Battery A1 is the battery of the present application, and batteries Z1 to Z3 are batteries of comparative examples. It should be noted that the life index in Table 1 is a relative value in which the life index X of each battery is standardized with the value of the life index X of battery A1 as 100. The "main component of the solute" in the table means a solute that accounts for more than 50 mol% of the total solute. The ratio Wm / Wn and the ratio We / Wp in the table are the above-mentioned ratios.

[0118] [Table 1]

[0119]

[0120] As shown in Table 1, in batteries Z1 and Z2 in which the metal compound is a compound of a rare earth element such as Y2O3 and Yb2O3, the life index is low. In addition, in battery Z3 in which the metal compound does not contain iron, the life index is also low. This can be considered to be due to the above-mentioned reasons. On the other hand, the life index of battery A1 of the present application is high. A high life index means that the battery's characteristics are less reduced in either the case of trickle charging at high temperature or the trickle charging at low temperature. On the other hand, it is considered that in the battery of the comparative example with a low life index, the battery's characteristics are significantly reduced in at least one of the trickle charging at high temperature and the trickle charging at low temperature.

[0121] (Experimental Example 2)

[0122] In Experimental Example 2, various nickel-metal hydride storage batteries were produced by changing the amount of the metal compound added to the positive electrode mixture. Specifically, the positive electrode was produced by changing the amount of the metal compound added to the positive electrode paste so that the value of the ratio Wm / Wn was the value shown in Table 2. Batteries Z4 to Z5 and batteries B1 to B4 were produced by the same method and conditions as battery A1, except that the amount of the metal compound was changed.

[0123] After the manufactured battery was activated in the same manner as in Experimental Example 1, it was evaluated using the same method as in Experimental Example 1. Part of the manufacturing conditions of the battery and the evaluation results are shown in Table 2. Batteries B1 to B4 are batteries of the present application, and batteries Z4 to Z5 are batteries of the comparative example. The life index in Table 2 is a relative value in which the life index X of each battery is standardized with the value of the life index X of battery B2 as 100. It should be noted that battery B2 is the same battery as battery A1.

[0124] [Table 2]

[0125]

[0126] As shown in Table 2, by setting the ratio Wm / Wn to a range of 0.2 / 100 to 5.0 / 100, a high life index can be achieved.

[0127] (Experimental Example 3)

[0128] In Experimental Example 3, various nickel-metal hydride storage batteries were produced by changing the metal compound added to the positive electrode mixture. Specifically, batteries C1 to C7 were produced by the same method and conditions as battery A1, except that the material of the metal compound was changed as shown in Table 3. The metal compound containing iron was produced by the same method as in Experimental Example 1.

[0129] After the manufactured battery was activated in the same manner as in Experimental Example 1, it was evaluated using the same method as in Experimental Example 1. Part of the manufacturing conditions of the battery and the evaluation results are shown in Table 3. Batteries C1 to C7 are batteries of the present application. The life index in Table 3 is a relative value obtained by standardizing the life index X of each battery with the value of the life index X of battery C1 as 100. It should be noted that battery C1 is the same battery as battery A1.

[0130] [Table 3]

[0131]

[0132] As shown in Table 3, a high life index can be achieved in any case where a compound of titanium, niobium, tungsten, vanadium, molybdenum, zirconium, or tantalum is used as the metal compound.

[0133] (Experimental Example 4)

[0134] In Experimental Example 4, various nickel-metal hydride storage batteries were produced by changing the value of the ratio We / Wp. Specifically, batteries D1 to D6 and batteries Z6 to Z7 were produced by the same method and conditions as battery A1, except that the value of the ratio We / Wp was changed as shown in Table 4. The value of the ratio We / Wp was changed by changing the amount of the alkaline electrolyte 17 contained in the battery case 4.

[0135] After the manufactured battery was activated in the same manner as in Experimental Example 1, it was evaluated using the same method as in Experimental Example 1. Part of the manufacturing conditions of the battery and the evaluation results are shown in Table 4. Batteries D1 to D6 are batteries of the present application, and batteries Z6 to Z7 are batteries of the comparative example. The life index in Table 4 is a relative value obtained by standardizing the life index X of each battery with the value of the life index X of battery D3 as 100. It should be noted that battery D3 is the same battery as battery A1.

[0136] [Table 4]

[0137]

[0138] As shown in Table 4, by setting the ratio We / Wp in the range of 0.35 to 1.0, a high life index can be achieved.

[0139] (Experimental Example 5)

[0140] In Experimental Example 5, various nickel-metal hydride storage batteries were produced by changing the iron content of the metal compound added to the positive electrode mixture. Specifically, batteries E1 to E4 and batteries Z8 to Z9 were produced using the same method and conditions as battery A1, except that the iron content of the metal compound was changed as shown in Table 5. When the metal compound was produced using the method described in Experimental Example 1, the amount of iron ions (iron compound) added to the raw material solution was changed, thereby changing the iron content.

[0141] After the manufactured battery was activated in the same manner as in Experimental Example 1, it was evaluated using the same method as in Experimental Example 1. Part of the manufacturing conditions of the battery and the evaluation results are shown in Table 5. Batteries E1 to E4 are batteries of the present application, and batteries Z8 to Z9 are batteries of comparative examples. The life index in Table 5 is a relative value obtained by standardizing the life index X of each battery with the value of the life index X of battery E3 as 100. It should be noted that battery E3 is the same battery as battery A1.

[0142] [Table 5]

[0143]

[0144] As shown in Table 5, by setting the iron content in the metal compound to a range of 10 to 1000 ppm, a high life index can be achieved.

[0145] (Experimental Example 6)

[0146] In Experimental Example 6, various nickel-metal hydride storage batteries were produced by changing the configuration of the negative electrode mixture layer 1B. Specifically, in battery F1 (A1), the thickness Din and Dout of the portions 11B and 12B of the negative electrode mixture layer 1B formed on the inner side (inner peripheral side) and the outer side (outer peripheral side) of the negative electrode current collector 1A were set to approximately 110 μm, respectively. In battery F2, at the outermost periphery of the negative electrode 1, the thickness Din and Dout of the portions 11B and 12B of the negative electrode mixture layer 1B formed on the inner side and the outer side of the negative electrode current collector 1A were set to approximately 80 μm, respectively, and the thickness of the negative electrode mixture layer 1B outside the outermost periphery (the thickness of the layer formed on one side) was set to approximately 130 μm. In battery F3, at the outermost periphery of the negative electrode 1 in the wound body 16, the thickness Dout of the portion 12B of the negative electrode mixture layer 1B formed on the outside of the negative electrode collector 1A is set to about 75 μm, the thickness Din of the portion 11B of the negative electrode mixture layer 1B formed on the inner side of the negative electrode collector 1A is set to about 145 μm, and the thicknesses of the portions 11B and 12B of the negative electrode mixture layer 1B other than the outermost periphery are respectively set to about 110 μm. In the battery F4, at the outermost periphery of the negative electrode 1 in the wound body 16, the thickness Din of the portion 11B of the negative electrode mixture layer 1B formed on the inner side of the negative electrode collector 1A was set to about 105 μm, the thickness Dout of the portion 12B of the negative electrode mixture layer 1B formed on the outer side of the negative electrode collector 1A was set to about 55 μm, and the thicknesses of the portions 11B and 12B of the negative electrode mixture layer 1B outside the outermost periphery were set to about 130 μm, respectively. Batteries F2 to F4 were produced by the same method and under the same conditions as those of the battery A1 except that these negative electrodes 1 were used. The battery F1 was set to be the same battery as the battery A1.

[0147] The manufactured battery was activated in the same manner as in Experimental Example 1, and then evaluated in the same manner as in Experimental Example 1. Part of the manufacturing conditions of the battery and the evaluation results are shown in Table 6. Batteries F1 to F4 are batteries of the present application. The life index in Table 6 is a relative value obtained by normalizing the life index X of each battery with the value of the life index X of battery F1 being 100.

[0148] [Table 6]

[0149]

[0150] As shown in Table 6, by adopting any of the above-mentioned structures (6) to (8), a higher life index can be achieved.

[0151] (Experimental Example 7)

[0152] In Experimental Example 7, various nickel-metal hydride storage batteries were produced by changing the material of the alkaline electrolyte 17. Specifically, in the alkaline electrolyte 17 of the battery G2, KOH, NaOH, and LiOH were mixed as the solute of the alkaline electrolyte at a molar ratio of KOH:NaOH:LiOH=2:7:0.5. The concentration of the alkaline electrolyte 17 and the spacing of the spacer 3 (13) per 1 cm 2 The amount of alkaline electrolyte 17 in the apparent area was the same as that of battery A1. Battery G2 was produced by the same method and conditions as battery A1 except for using this alkaline electrolyte 17. Battery G1 was the same as battery A1.

[0153] The manufactured battery was activated in the same manner as in Experimental Example 1, and then evaluated in the same manner as in Experimental Example 1. A portion of the manufacturing conditions of the battery and the evaluation results are shown in Table 7. Batteries G1 and G2 are batteries of the present application. The life index in Table 7 is a relative value obtained by standardizing the life index X of each battery with the value of the life index X of battery G1 being 100.

[0154] [Table 7]

[0155]

[0156] As shown in Table 7, by setting the main component of the solute to NaOH, a higher life index can be achieved.

[0157] Industrial Applicability

[0158] The present application can be used for alkaline batteries.

[0159] Description of Reference Numerals

[0160] 1 negative electrode, 2 positive electrode, 3 separator, 4 battery case, 7 sealing body, 8 insulating gasket, 9 positive electrode collector plate, 10 alkaline battery.

Claims

1. An alkaline storage battery comprising a positive electrode, a negative electrode, a separator provided between the positive electrode and the negative electrode, and an alkaline electrolyte, The positive electrode comprises a positive electrode current collector and a positive electrode mixture supported by the positive electrode current collector. The positive electrode mixture contains a nickel compound and a metal compound as positive electrode active materials. The metal compound is a compound of at least one metal element selected from titanium, niobium, tungsten, vanadium, molybdenum, zirconium and tantalum, a ratio Wm / Wn of a mass Wm of the metal compound contained in the positive electrode mixture to a mass Wn of the nickel compound contained in the positive electrode mixture converted into nickel hydroxide, which is in a range of 0.2 / 100 to 5.0 / 100, The metal compound contains iron in a range of 10 ppm to 10000 ppm by mass, The ratio We / Wp of the mass We of the alkaline electrolyte to the mass Wp of the positive electrode mixture is in the range of 0.35 to 1.

0.

2. The alkaline storage battery according to claim 1, wherein The positive electrode, the negative electrode, and the separator are stacked and wound to form a wound body. The negative electrode comprises a negative electrode current collector and a negative electrode mixture layer disposed on the negative electrode current collector. The negative electrode mixture layer comprises a hydrogen storage alloy. In the wound body, the outermost periphery of the negative electrode is outside the outermost periphery of the positive electrode, The mass of the hydrogen storage alloy per unit area of ​​the outermost circumference of the negative electrode is smaller than the mass of the hydrogen storage alloy per unit area of ​​a portion other than the outermost circumference of the negative electrode.

3. The alkaline storage battery according to claim 2, wherein The thickness of the negative electrode mixture layer at the outermost periphery of the negative electrode is smaller than the thickness of the negative electrode mixture layer on the inner side with respect to the outermost periphery of the negative electrode in the wound body.

4. The alkaline storage battery according to claim 2, wherein The negative electrode is wound such that the negative electrode mixture layer has a first portion disposed outside the negative electrode current collector and a second portion disposed inside the negative electrode current collector at the outermost periphery of the negative electrode, The thickness of the first portion of the negative electrode mixture layer is smaller than the thickness of the second portion of the negative electrode mixture layer.

5. The alkaline storage battery according to any one of claims 1 to 4, wherein The alkaline electrolyte is an electrolyte containing sodium hydroxide and potassium hydroxide, The concentration of the sodium hydroxide in the alkaline electrolyte is higher than the concentration of the potassium hydroxide in the alkaline electrolyte.

6. The alkaline storage battery according to any one of claims 1 to 4, wherein The alkaline electrolyte is an electrolyte containing sodium hydroxide and not containing potassium hydroxide.

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