JP2010044907A - Flat-type alkaline primary battery and manufacturing method of flat-type alkaline primary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat-type alkaline primary battery that can improve handling performance and capacity storage performance, and a manufacturing method there of the flat-type alkaline primary battery. <P>SOLUTION: In a flat-type alkaline primary battery 1 housing a positive electrode mixture 5, a negative electrode mixture 7, and an electrolytic solution in a case 8, the positive electrode mixture 5 contains nickel oxyhydroxide the surface of which is coated with a γ-cobalt oxyhydroxide as a main positive electrode active material while the negative electrode mixture 7 uses zinc powder or zinc alloy powder as a main negative electrode active material, and contains carboxymethyl cellulose and a cross-linked polyacrylic acid or its salts as a thickener. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a flat alkaline primary battery and a method for producing a flat alkaline primary battery.

  A coin-type or button-type alkaline primary battery used in a small electronic device such as an electronic wristwatch or a portable electronic computer includes a positive electrode mixture and a negative electrode mixture in a flat case. The positive electrode mixture and the negative electrode mixture housed in the case face each other via a separator, and the positive electrode mixture, the negative electrode mixture, and the separator are filled with an electrolytic solution.

  As such an alkaline primary battery, a silver oxide battery using silver oxide as a positive electrode active material and an alkaline manganese battery using manganese dioxide as a positive electrode active material are already on the general market. Silver oxide batteries have the advantage of high volumetric energy density, and when the negative electrode active material is zinc, the battery voltage is flat around 1.56 volts. For this reason, the oxygen silver battery is suitable for a power source for small electronic devices such as electronic wristwatches and portable electronic computers whose end voltage is 1.2 volts or more.

  However, silver oxide is expensive because silver, which is a noble metal, is the main component, and the price fluctuates depending on the silver market price, and is a substance that is difficult to use in order to reduce and stabilize manufacturing costs. On the other hand, the alkaline manganese battery is advantageous in that the price per mass is overwhelmingly low. However, alkaline manganese batteries have a lower volumetric energy density than silver oxide, and the voltage drops significantly with discharge. For this reason, in devices such as electronic wristwatches where the end voltage is set higher in accordance with the battery voltage of the silver oxide battery, the usage time of the device becomes extremely short due to the voltage drop caused by the discharge of manganese dioxide. There is a problem.

As a solution, a battery containing nickel oxyhydroxide as a positive electrode active material has been proposed. Nickel oxyhydroxide can make a battery voltage higher than that of a silver oxide battery, and is already used as a positive electrode active material in a cylindrical battery (see, for example, Patent Documents 1 to 3).
JP 2003-234107 A JP 2004-6092 A JP-A-2005-19349

  However, in the case of a battery using nickel oxyhydroxide as the positive electrode active material, although the battery voltage is higher than that of the silver oxide battery, the theoretical electric capacity per unit mass of nickel oxyhydroxide is 292 mAh / g, It is smaller than 308 mAh / g manganese (per manganese value).

  On the other hand, a cellulose-based thickener is used as a thickener for improving the handleability of the negative electrode mixture. When a cellulosic thickener is blended in the negative electrode mixture, the thickener will be decomposed by the oxidizing action of nickel oxyhydroxide contained in the positive electrode mixture when the battery is stored at high temperature. When the thickener is decomposed, the electrolyte solution around the zinc or zinc alloy powder, which is the negative electrode active material, becomes insufficient, and the zinc is passivated, resulting in a decrease in electric capacity.

  The present invention has been made in view of the above problems, and an object thereof is to provide a flat alkaline primary battery and a flat alkaline primary battery manufacturing method capable of improving handling properties and capacity storage. It is in.

  In order to solve the above problems, the present invention provides a flat alkaline primary battery in which a positive electrode mixture, a negative electrode mixture, and an electrolytic solution are housed in a case, and the positive electrode mixture has a surface of γ-cobalt oxyhydroxide. In addition, the negative electrode mixture includes zinc or zinc alloy powder as a main negative electrode active material, and carboxymethyl cellulose and cross-linked polyacrylic acid or salts thereof as a thickener. Include as.

  According to the above configuration, since the positive electrode mixture contains nickel oxyhydroxide whose surface is coated with γ-cobalt oxyhydroxide as the main positive electrode active material, the oxidizing power of nickel oxyhydroxide acting on the negative electrode mixture Can be reduced. In addition, since the negative electrode mixture contains carboxymethylcellulose and cross-linked polyacrylic acid or salts thereof as a thickener, handling properties and oxidation resistance can be improved. For this reason, the battery excellent in handling property and capacity storage can be provided.

In this flat alkaline primary battery, the compounding ratio of the carboxymethyl cellulose in the negative electrode mixture is 1.5% by mass or more and 2.5% by mass or less.
According to the said structure, since the compounding ratio of carboxymethylcellulose is 1.5 mass% or more and 2.5 mass% or less, favorable handling property can be obtained.

In this flat alkaline primary battery, a blending ratio of the cross-linked polyacrylic acid or a salt thereof in the negative electrode mixture is 0.3% by mass or more and 1.5% by mass or less.
According to the said structure, since the compounding ratio of bridge | crosslinking-type polyacrylic acid or its salts is 0.3 mass% or more and 1.5 mass% or less, handling property is made favorable and the oxidation resistance of a negative electrode mixture Can be improved, and the capacity preservation can be improved.

In this flat alkaline primary battery, the compounding ratio of the carboxymethyl cellulose and the crosslinked polyacrylic acid or a salt thereof is 1: 0.1 to 1: 0.7.
According to the above configuration, since the compounding ratio of the cross-linked polyacrylic acid or its salt is 0.1 or more and 0.7 or less with respect to carboxymethylcellulose, the negative electrode mixture is maintained while maintaining good handling properties. It is possible to improve the storage resistance and improve the capacity storage stability.

  The present invention provides a method for producing a flat alkaline primary battery in which a positive electrode mixture, a negative electrode mixture, and an electrolytic solution are housed in a case, wherein the positive electrode mixture is coated with γ-cobalt oxyhydroxide on the surface. Nickel is blended as the main positive electrode active material, zinc or zinc alloy powder is used as the main negative electrode active material, and carboxymethyl cellulose and cross-linked polyacrylic acid or salts thereof are blended as thickeners.

  According to the above method, since the positive electrode mixture contains nickel oxyhydroxide whose surface is coated with γ-cobalt oxyhydroxide as the main positive electrode active material, the oxidizing power of nickel oxyhydroxide acting on the negative electrode mixture Can be reduced. In addition, since the negative electrode mixture contains carboxymethylcellulose and cross-linked polyacrylic acid or salts thereof as a thickener, handling properties and oxidation resistance can be improved. For this reason, the battery excellent in handling property and capacity storage can be provided.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIG.
FIG. 1 is a schematic cross-sectional view of a flat alkaline primary battery in which a positive electrode mixture, a negative electrode mixture, and an electrolytic solution are housed in a flat case. The flat alkaline primary battery 1 is a button-type primary battery, and includes a positive electrode can 2 and a negative electrode can 3. The positive electrode can 2 is made of stainless steel (SU
It is made of a material plated with nickel on S) and molded into a cup shape. The positive electrode can 2 accommodates the positive electrode mixture 5 and functions as a positive electrode terminal.

  The negative electrode can 3 is made of a clad material having a three-layer structure of an outer surface layer made of nickel, a metal layer made of stainless steel (SUS), and a current collector layer made of copper, and is molded in a cup shape. The negative electrode can 3 has a circular opening 3a formed in a folded shape, and a ring-shaped gasket 4 made of nylon, for example, is attached to the opening 3a.

  Then, the negative electrode can 3 is fitted into the circular opening 2a of the positive electrode can 2 from the opening 3a side where the gasket 4 is mounted, and the opening 2a of the positive electrode can 2 is caulked toward the gasket 4 to seal it. By doing so, a disk-shaped (button-shaped or coin-shaped) case 8 is formed. A sealed space S is formed inside the case 8.

In this sealed space S, the positive electrode mixture 5, the separator 6, and the negative electrode mixture 7 are accommodated, and the positive electrode mixture 5 is disposed on the positive electrode can 2 side and the negative electrode mixture 7 is disposed on the negative electrode can 3 side with the separator 6 interposed therebetween. Has been.
(Positive electrode mixture)
Next, the positive electrode mixture 5 will be described. The positive electrode mixture 5 contains a main positive electrode active material, a conductive agent, a binder, and an electrolytic solution. The main positive electrode active material is made of nickel oxyhydroxide powder whose surface is coated with γ-cobalt oxyhydroxide. The discharge reaction of nickel oxyhydroxide is represented by the following half reaction formula (1).

NiOOH + H ₂ O + e ⁻ → Ni (OH) ₂ + OH ⁻ (1)
Nickel oxyhydroxide itself has low conductivity, and nickel hydroxide produced by the discharge reaction has almost no conductivity. Moreover, since the volume of nickel hydroxide produced by the discharge reaction is larger than that of nickel oxyhydroxide, the positive electrode mixture 5 expands as the proportion of nickel hydroxide increases. When nickel oxyhydroxide is not coated with γ-cobalt oxyhydroxide or the like, the ratio of the conductive agent per volume in the positive electrode mixture decreases with discharge, and the capacity decreases.

  On the other hand, in the present invention, the surface of nickel oxyhydroxide particles is coated with γ-cobalt oxyhydroxide. Thereby, the coating layer of γ-cobalt oxyhydroxide acts as an outer shell of the nickel oxyhydroxide particles, and the volume expansion can be suppressed. Moreover, since (gamma) -cobalt oxyhydroxide has high electroconductivity, the ratio of a electrically conductive agent can also be improved.

  Moreover, the weighability of the positive electrode mixture 5 can be improved by coating the surface of nickel oxyhydroxide with γ-cobalt oxyhydroxide, which is more slippery than nickel oxyhydroxide. Furthermore, by coating nickel oxyhydroxide having a large oxidizing power with γ-cobalt oxyhydroxide, the oxidizing power acting on the negative electrode mixture 7 can be reduced.

  Moreover, although graphite is used as the conductive agent, other conductive agents such as metal powder may be used. Furthermore, although polyacrylic acid soda is used as the binder, other binders such as polytetrafluoroethylene (PTFE) may be used. As the electrolytic solution, an aqueous potassium hydroxide solution, an aqueous sodium hydroxide solution, or the like can be used.

These compositions are mixed and press-molded with a tableting machine or the like to form cylindrical pellets, and the pellets are accommodated in the positive electrode can 2.
(Negative electrode mixture)
The negative electrode mixture 7 contains zinc or zinc alloy powder, zinc oxide, a thickener, an alkaline electrolyte, a zinc corrosion inhibitor, and the like, and is formed in a gel form. The discharge reaction of zinc or zinc alloy as the negative electrode active material is represented by the following half reaction formula (2).

Zn + 2OH ⁻ → ZnO + H ₂ O + 2e ⁻ (2)
As the thickener, carboxymethylcellulose and cross-linked polyacrylic acid or salts thereof are used. Carboxymethylcellulose is blended in an appropriate amount in the negative electrode mixture 7, thereby making the viscosity and strength of the negative electrode mixture 7 suitable for the battery assembly process and improving the handling properties of the negative electrode mixture 7. In addition, handling property shows the ease of handling at the time of assembling a battery. The negative electrode mixture 7 includes, for example, the ease of placing the negative electrode mixture 7 on the separator and the ease of filling the negative electrode mixture 7 into the negative electrode can 3. When the handling property is deteriorated, the yield decreases, for example, the filling amount varies. In addition, if the handling property is extremely poor, the placement of the negative electrode mixture 7 and the filling into the negative electrode can 3 become impossible, and the battery cannot be assembled.

On the other hand, when the battery is stored at a high temperature, this carboxymethyl cellulose is easily decomposed by the oxidizing power of the positive electrode mixture 5, and there is a problem that the capacity storage stability of the battery is lowered.
Crosslinked polyacrylic acid and its salts have excellent oxidation resistance and are not decomposed by the oxidizing power of the positive electrode mixture 5, but are viscoelastically higher than carboxymethylcellulose. As a result, handling is reduced. As the crosslinkable polyacrylate, a crosslinkable sodium polyacrylate can be used.

  For this reason, in this invention, the oxidation resistance with respect to the positive mix 5 and handling property are made compatible by mix | blending both carboxymethylcellulose and bridge | crosslinking type polyacrylic acid or its salts with the negative mix 7. . Further, by coating the nickel oxyhydroxide contained in the positive electrode mixture 5 with cobalt oxyhydroxide having a lower conductivity than the nickel oxyhydroxide, the oxidizing power of the positive electrode mixture 5 is weakened, and the blending amount of carboxymethyl cellulose Is increased to such an amount that good handling properties can be obtained. In addition, by adjusting the blending ratio of carboxymethyl cellulose, the blending ratio of cross-linked polyacrylic acid or salts thereof, and the blending ratio of carboxymethyl cellulose and cross-linking polyacrylic acid or salts thereof as follows, oxidation resistance and The balance of handling is aimed at.

  Specifically, the blending ratio of carboxymethyl cellulose is preferably 1.5% by mass or more and 2.5% by mass or less with respect to the total mass of the positive electrode mixture 5. If the carboxymethyl cellulose content is less than 1.5% by mass, sufficient strength for the negative electrode mixture 7 to be handled as a semi-solid cannot be obtained. When the blending ratio of carboxymethyl cellulose exceeds 2.5% by mass, the viscoelasticity of the negative electrode mixture 7 becomes excessively high. For example, handling when the negative electrode mixture 7 is filled in the negative electrode can 3 is not easy.

  Moreover, it is preferable that the compounding rate of bridge | crosslinking-type polyacrylic acid or its salt shall be 0.3 to 1.5 mass%. When the blending ratio of the cross-linked polyacrylic acid or its salt is less than 0.3% by mass, the blending ratio of carboxymethyl cellulose is increased accordingly, so that the electrolyte solution is insufficient due to decomposition of carboxymethyl cellulose. End up. Moreover, when a compounding rate exceeds 1.5 mass%, the viscosity of the negative mix 7 will become high, and the mounting property for accommodating the negative mix 7 in the negative electrode can 3 will worsen.

  Furthermore, it is preferable that the compounding ratio of carboxymethyl cellulose and crosslinked polyacrylic acid or salts thereof is 1: 0.1 to 1: 0.7 or less based on carboxymethyl cellulose. That is, the blending ratio of the cross-linked polyacrylic acid or its salt is preferably 0.1 or more and 0.7 or less with respect to carboxymethyl cellulose.

When the compounding ratio of the cross-linked polyacrylic acid or its salt is less than 0.1 with respect to carboxymethylcellulose, the amount of the cross-linked polyacrylic acid or its salt is reduced, so that the oxidation resistance is lowered and the capacity is preserved. Sex is reduced. When the compounding ratio of the cross-linked polyacrylic acid or a salt thereof exceeds 1: 0.7 with respect to carboxymethyl cellulose, the handling property is lowered by increasing the amount of the cross-linked polyacrylic acid or a salt thereof.

Next, the Example and the comparative example which changed the composition of the positive mix 5 were performed, and the effect of the said invention was verified.
Example 1
In the battery structure shown in FIG. 1, the negative electrode can 3 was molded by pressing the clad material having a thickness of 0.15 mm.

  The positive electrode mixture 5 was 93.8% by mass of nickel oxyhydroxide coated with γ-cobalt oxyhydroxide, 0.2% by mass of cross-linked polyacrylic acid, 4.0% by mass of fluororesin powder, and a concentration of 45 2% by mass of a potassium hydroxide aqueous solution was mixed with a blender, and then molded into pellets with a tableting machine. Further, the coverage of γ-cobalt oxyhydroxide was 3% by mass with respect to nickel oxyhydroxide.

The molded positive electrode mixture 5 was inserted into a positive electrode can, and an alkaline electrolyte containing potassium hydroxide was injected to cause the positive electrode mixture 5 to absorb the electrolyte.
Furthermore, a separator 6 composed of a microporous membrane 6a and a nonwoven fabric 6b was loaded on the positive electrode mixture, and the separator 6 was dropped and impregnated with an alkaline electrolyte containing a 37% strength potassium hydroxide aqueous solution.

The negative electrode mixture 7 was composed of 61.0% by mass of zinc alloy powder, 2.68% by mass of zinc oxide, 0.75% by mass of cross-linked sodium polyacrylate (PAS), and 2.21 of carboxymethyl cellulose (CMC). An aqueous potassium hydroxide solution having a mass% and a concentration of 45% was mixed with 33.36% by mass. Then, the gelled negative electrode mixture 7 was placed on the separator, and the negative electrode can 3 and the positive electrode can 2 were sealed by caulking through the gasket 4 to produce a flat alkaline primary battery 1. (Example 2)
In Example 2, the same configuration as in Example 1 was used, but the blending ratio of carboxymethyl cellulose contained in the negative electrode mixture 7 was 1.5 mass%.
(Example 3)
In Example 3, the composition was the same as in Example 1, but the blending ratio of carboxymethylcellulose contained in the negative electrode mixture 7 was 2.5 mass%.
Example 4
In Example 4, although the same configuration as in Example 1 was used, the blending ratio of the crosslinked polyacrylic acid soda contained in the negative electrode mixture 7 was set to 0.3% by mass.
(Example 5)
In Example 5, the composition was the same as in Example 1, but the blending ratio of the cross-linked sodium polyacrylate contained in the negative electrode mixture 7 was 1.5 mass%.
(Example 6)
In Example 6, the same configuration as in Example 1 was used, but the compounding ratio of carboxymethyl cellulose and cross-linked sodium polyacrylate contained in the negative electrode mixture 7 was 1: 0.1.
(Example 7)
In Example 7, the composition was the same as in Example 1, but the compounding ratio of carboxymethyl cellulose and cross-linked sodium polyacrylate contained in the negative electrode mixture 7 was 1: 0.7.
(Example 8)
In Example 8, although the same configuration as in Example 1 was used, the blending ratio of carboxymethyl cellulose contained in the negative electrode mixture 7 was set to 1.3% by mass.
Example 9
In Example 9, although the same configuration as in Example 1 was used, the blending ratio of carboxymethyl cellulose contained in the negative electrode mixture 7 was set to 2.7% by mass.
(Example 10)
In Example 10, the same configuration as that in Example 1 was used, but the blending ratio of the cross-linked sodium polyacrylate contained in the negative electrode mixture 7 was set to 0.1% by mass.
(Example 11)
In Example 11, the composition was the same as in Example 1, but the blending ratio of the crosslinked polyacrylic acid soda contained in the negative electrode mixture 7 was 1.7% by mass.
(Comparative Example 1)
Comparative Example 1 was different from Example 1 in that carboxymethyl cellulose was not blended as a thickener for the negative electrode mixture 7, and other configurations were the same as those in Example 1.
(Comparative Example 2)
Comparative Example 2 was different from Example 1 in that no cross-linked sodium polyacrylate was added as a thickener for the negative electrode mixture 7, and the other configuration was the same as that of Example 1.
<Verification>
Then, 40 flat alkaline primary batteries 1 of Examples 1 to 11 and Comparative Examples 1 and 2 described above were produced, respectively, and the following verification was performed.
<Verification 1>
Discharge capacity [mAh] at the time of making a constant resistance discharge at 30 kΩ and setting a final voltage of 1.4 V to 20 batteries each manufactured was examined. The results are shown in the table of FIG.
<Verification 2>
The batteries produced in units of 20 were stored for 60 days in an environment of temperature 60 ° C. and humidity dry, then subjected to constant resistance discharge at 30 kΩ, and the discharge capacity [mAh] when the final voltage was 1.4 V was examined. The results are shown in the table of FIG.
<Verification 3>
When producing a battery, the handling property of the negative electrode mixture 7 was evaluated. The result is shown in FIG.

  In Comparative Example 1 in which carboxymethylcellulose was not blended, the strength required for battery assembly could not be obtained, and the flat alkaline primary battery 1 could not be produced. Moreover, although the comparative example 2 which does not mix | blend bridge | crosslinking-type polyacryl soda has favorable handling property, compared with Examples 1-11, the discharge capacity obtained by verification 2 was low. This suggests that a battery with excellent handling and capacity storage can be obtained by constructing the thickener from carboxymethylcellulose and cross-linked polyacrylate (or cross-linked polyacrylic acid). It was done.

  -Moreover, Examples 1-3 which made the compounding ratio of carboxymethylcellulose 1.5 mass% or more and 2.5 mass% or less made the compounding ratio 1.3 mass% and 2.7 mass%, respectively. Good handling properties could be obtained for Examples 8 and 9. Thereby, it was suggested that handling property can be improved by making the compounding ratio of carboxymethylcellulose into 1.5 mass% or more and 2.5 mass% or less with respect to the negative mix 7.

  In Examples 1, 4 and 5 in which the blending ratio of the cross-linked polyacrylic soda was 0.3% by mass or more and 1.5% by mass or less, Example 10 in which the blending ratio was 0.1% by mass, respectively. As compared with the above, the discharge capacity obtained in the verification 2 was increased. Further, in Examples 1, 4 and 5, good handling properties were obtained as compared with Example 11 in which the blending ratio of the crosslinked polyacrylic soda was 1.7% by mass. Thereby, it was suggested that capacity | capacitance preservability and handling property can be improved by making the compounding rate of bridge | crosslinking type polyacrylate (or bridge | crosslinking type polyacrylic acid) into the said range.

In Examples 6 and 7, in which the mixing ratio of carboxymethyl cellulose and cross-linked sodium polyacrylate in the negative electrode mixture was 1: 0.1 and 1: 0.7, respectively, the mixing ratio was 1: 0.05. Compared to a certain example 10, the capacity preservation was good. In addition, Examples 6 and 7 had better handling properties than Example 11 in which the blending ratio of carboxymethyl cellulose and crosslinked polysodium acrylate was 1: 0.07. It was suggested that capacity preservation and handling properties can be improved by setting the blending ratio of carboxymethyl cellulose and cross-linked polyacrylic acid (or cross-linked polyacrylic acid) within the above range.

According to the above embodiment, the following effects can be obtained.
(1) In the said embodiment, the positive mix 5 contains the nickel oxyhydroxide which coat | covered the surface with (gamma) -cobalt oxyhydroxide as a main positive electrode active material. For this reason, the oxidizing power of nickel oxyhydroxide acting on the negative electrode mixture 7 can be reduced. The negative electrode mixture 7 includes zinc or zinc alloy powder as a main negative electrode active material, and includes both carboxymethyl cellulose and cross-linked polyacrylic acid or salts thereof as a thickener. For this reason, carboxymethylcellulose can improve the handling, and the cross-linked polyacrylic acid or its salts can improve the oxidation resistance and prevent the thickener from decomposing when the battery is stored at high temperature. As a result, since the electrolyte solution in the negative electrode mixture 7 can be maintained in an appropriate amount by the thickener, it is possible to prevent a decrease in capacity due to the passivation of zinc. Therefore, it is possible to provide a battery having excellent handling properties and capacity storage.

  (2) In the said embodiment, the compounding ratio of the carboxymethylcellulose in the negative mix 7 was 1.5 mass% or more and 2.5 mass% or less. For this reason, the intensity | strength for handling the negative mix 7 as a semi-solid, the filling property to the negative electrode can 3, etc. can be improved, and handling property can be improved.

  (3) In the said embodiment, the compounding rate of bridge | crosslinking type polyacrylic acid or its salts in the negative mix 7 was 0.3 mass% or more and 1.5 mass% or less. For this reason, while maintaining favorable handling property, the oxidation resistance of the negative electrode mixture 7 can be improved and the capacity storage stability can be improved.

  (4) In the said embodiment, since the compounding ratio of the carboxymethylcellulose in the negative mix 7 and bridge | crosslinking-type polyacrylic acid or its salt is 1: 0.1-1: 0.7, favorable handling property is sufficient. While maintaining the above, it is possible to improve the oxidation resistance of the negative electrode mixture and improve the capacity storage stability.

In addition, you may change the said embodiment as follows.
-Nickel oxyhydroxide as the main positive electrode active material may be a single nickel oxyhydroxide coated with γ-cobalt oxyhydroxide, or γ-oxywater in nickel oxyhydroxide in which zinc or cobalt is dissolved. Cobalt oxide may be coated.

Sectional drawing of a flat alkaline primary battery. The table | surface of an Example and a comparative example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Flat alkaline primary battery, 5 ... Positive electrode mixture, 7 ... Negative electrode mixture, 8 ... Case.

Claims (5)

In the flat alkaline primary battery in which the positive electrode mixture and the negative electrode mixture and the electrolytic solution are accommodated in the case,
The positive electrode mixture includes, as a main positive electrode active material, nickel oxyhydroxide whose surface is coated with γ-cobalt oxyhydroxide,
The flat alkaline primary battery, wherein the negative electrode mixture includes zinc or zinc alloy powder as a main negative electrode active material and carboxymethyl cellulose and crosslinked polyacrylic acid or a salt thereof as a thickener. The flat alkaline primary battery according to claim 1,
The flat alkaline primary battery, wherein a mixing ratio of the carboxymethyl cellulose in the negative electrode mixture is 1.5% by mass or more and 2.5% by mass or less. The flat alkaline primary battery according to claim 1 or 2,
A flat alkaline primary battery, wherein a blending ratio of the cross-linked polyacrylic acid or a salt thereof in the negative electrode mixture is 0.3% by mass or more and 1.5% by mass or less. The flat alkaline primary battery according to any one of claims 1 to 3,
A flat alkaline primary battery, wherein a blending ratio of the carboxymethyl cellulose and the cross-linked polyacrylic acid or a salt thereof is 1: 0.1 to 1: 0.7. In the method for producing a flat alkaline primary battery in which a positive electrode mixture and a negative electrode mixture and an electrolyte solution are housed in a case,
While blending the positive electrode mixture as a main positive electrode active material nickel oxyhydroxide whose surface is coated with γ-cobalt oxyhydroxide,
A method for producing a flat alkaline primary battery, wherein zinc or a zinc alloy powder is used as a main negative electrode active material, and carboxymethyl cellulose and cross-linked polyacrylic acid or salts thereof are blended as a thickener.

Images