JP2010170909A - Manufacturing method for flat primary battery, and flat primary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a flat primary battery having suitable battery capacity at low costs, and the flat primary battery. <P>SOLUTION: In the manufacturing method for the flat primary battery 1 for storing a positive electrode mixture 5 in a positive electrode can 2, the positive electrode mixture 5 including nickel oxyhydroxide and silver oxide is stored in the positive electrode can 2, silver-nickel complex oxide is produced by reacting the nickel oxyhydroxide and the silver oxide in the positive electrode can 2, and a mass ratio of the silver oxide is set up to be 1.2 or more to the nickel oxyhydroxide. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  Flat primary batteries, such as coin-type or button-type, used for small electronic devices such as electronic watches, silver oxide batteries using silver oxide as the positive electrode mixture, and alkaline buttons using manganese dioxide as the positive electrode mixture Batteries have already been produced.

  Since the silver oxide battery has a high volumetric energy density and a flat battery voltage of 1.56 volts when the negative electrode active material is zinc, it is a small electronic device such as an electronic wristwatch with a final voltage of 1.2 volts or more. It is used as a power source for equipment.

However, although silver oxide has good performance, it is expensive because silver, which is a noble metal, is the main component, and is difficult to use in order to reduce and stabilize manufacturing costs.
On the other hand, manganese dioxide has the advantage that the price per mass is over 1/100 that of silver oxide and is overwhelmingly inexpensive. However, manganese dioxide has a lower volumetric energy density and inferior flatness of the discharge potential than silver oxide. Therefore, when used in a device whose end voltage is set high, there is a problem that the usage time of the device becomes extremely short due to a voltage drop caused by discharge of manganese dioxide.

  On the other hand, a battery using nickel oxyhydroxide as a positive electrode active material has been proposed (see, for example, Patent Document 1). Nickel oxyhydroxide has a higher discharge voltage than silver oxide.

JP 2008-210719 A

  However, nickel oxyhydroxide has a defect that the discharge voltage is less flat than silver oxide. Further, nickel oxyhydroxide has a lower theoretical electric capacity per unit mass than the theoretical electric capacity per monovalent of manganese dioxide, and improvement of the battery capacity has been a problem.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for manufacturing a flat primary battery having a low battery capacity and good battery capacity, and a flat primary battery.
Another object of the present invention is to provide a method for producing a flat primary battery and a flat primary battery capable of shortening the reaction time between nickel oxyhydroxide and silver oxide.

  In order to solve the above problems, the present invention provides a method for producing a flat primary battery in which a positive electrode mixture is accommodated in a positive electrode can, and the positive electrode mixture containing nickel oxyhydroxide and silver oxide, together with an electrolyte, The positive electrode can is accommodated, and the nickel oxyhydroxide and the silver oxide are reacted in the positive electrode can to produce a silver / nickel composite oxide, and the mass ratio of the silver oxide is determined based on the mass ratio of the silver oxyhydroxide. 1.2 or more with respect to nickel.

According to this, since the mass ratio of silver oxide is 1.2 or more with respect to nickel oxyhydroxide, all nickel oxyhydroxide is reacted with silver oxide.
In the method for manufacturing a flat primary battery, the ratio of the electrolytic solution is 5% by mass or more and 10% by mass or less with respect to the positive electrode mixture.

  According to this, since the ratio of the electrolytic solution is 5% by mass or more and 10% by mass or less with respect to the positive electrode mixture, the reaction between silver oxide and nickel oxyhydroxide is facilitated and the leakage resistance is improved. be able to.

In the method for manufacturing a flat primary battery, the electrolytic solution is an aqueous potassium hydroxide solution, and the concentration thereof is 30% or more and 45% or less.
According to this, since the electrolytic solution is an aqueous potassium hydroxide solution and the concentration thereof is 30% or more and 45% or less, the reaction between silver oxide and nickel oxyhydroxide is facilitated, and the battery characteristics and leakage resistance are improved. Can be improved.

In the method for manufacturing a flat primary battery, the electrolytic solution is an aqueous sodium hydroxide solution having a concentration of 20% or more and 35% or less.
According to this, since the electrolytic solution is a sodium hydroxide aqueous solution and the concentration thereof is 20% or more and 35% or less, the reaction between silver oxide and nickel oxyhydroxide is facilitated, and battery characteristics and leakage resistance are prevented. Can be improved.

The flat primary battery of the present invention is manufactured by the above manufacturing method.
According to this, since the mass ratio of silver oxide is 1.2 or more with respect to nickel oxyhydroxide, all the nickel oxyhydroxide can be reacted with silver oxide.

Sectional drawing of the flat primary battery of this embodiment. The table | surface which shows the examination result of an Example and a comparative example.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view of a flat primary battery. In FIG. 1, a flat primary battery 1 is a button-type primary battery, and includes a bottomed cylindrical positive electrode can 2 and a covered cylindrical negative electrode can 3. The positive electrode can 2 has a structure in which nickel plating is applied to stainless steel (SUS), and also serves as a positive electrode terminal.

  The negative electrode can 3 is formed by pressing a three-layer clad material of an outer surface layer 3A made of nickel, a metal layer 3B made of stainless steel (SUS), and a current collector layer 3C made of copper into a cup shape. ing. Further, the negative electrode can 3 is formed such that its opening is bent along the outer peripheral surface, and, for example, a ring-shaped gasket 4 made of nylon is attached to the bent opening.

  Then, the negative electrode can 3 is fitted into the circular opening of the positive electrode can 2 from the opening side where the gasket 4 is mounted, and the opening of the positive electrode can 2 is crimped toward the gasket 4 and sealed. The positive electrode can 2 and the negative electrode can 3 are connected and fixed to each other. By connecting and fixing the positive electrode can 2 and the negative electrode can 3, a sealed space is formed between the positive electrode can 2 and the negative electrode can 3 via the gasket 4.

In this sealed space, a positive electrode mixture 5, a separator 6, and a negative electrode mixture 7 are accommodated. The positive electrode mixture 5 is formed in a cylindrical pellet and is placed on the bottom surface 2 b of the positive electrode can 2. This positive electrode mixture 5 is composed of a positive electrode active material containing a silver / nickel composite oxide (AgNiO ₂ ) produced by the reaction of nickel oxyhydroxide and silver oxide in a positive electrode can, and a binder. Has been.

  More specifically, in the manufacturing process of the flat primary battery 1, pellets in which nickel oxyhydroxide, silver oxide, a binder and the like are mixed are accommodated in the positive electrode can 2 together with an alkaline electrolyte. As a result, nickel oxyhydroxide and silver oxide react in the positive electrode can (see Formula 1) to produce a silver / nickel composite oxide.

2NiOOH + Ag ₂ O → 2AgNiO ₂ + H ₂ O (1)
The silver / nickel composite oxide functions as an active material in the positive electrode, and its battery voltage is about 1.35V on average, and can be sufficiently used for devices having a final voltage of 1.2V. Further, the silver / nickel composite oxide has an advantage that a theoretical energy density is higher than that of silver oxide, and a battery having excellent capacity can be obtained. Furthermore, the silver / nickel composite oxide has a high conductivity and a high binding force, and binds each particle in the positive electrode mixture to suppress swelling.

  The processing cost of this silver / nickel composite oxide is about 10 times that of nickel oxyhydroxide and several times higher than the processing cost of silver oxide. For this reason, by producing a silver / nickel composite oxide from nickel oxyhydroxide and silver oxide in the battery, a silver / nickel composite oxide having excellent battery characteristics can be produced at low cost.

  The mass ratio of nickel oxyhydroxide to silver oxide in the positive electrode mixture 5 is preferably 1: 1.2, and the silver oxide is increased. In other words, the silver oxide is preferably contained in a mass ratio of 1.2 (times) or more with respect to nickel oxyhydroxide. By setting the mass ratio of nickel oxyhydroxide and silver oxide in the positive electrode mixture 5 within the above range, all of the nickel oxyhydroxide contained in the positive electrode mixture 5 can be reacted without leaving silver oxide.

  If the ratio to silver oxide is less than 1.2, unreacted nickel oxyhydroxide may remain in the positive electrode mixture after completion of the reaction. When unreacted nickel oxyhydroxide remains in the positive electrode mixture, a potential near 1.6 V of nickel oxyhydroxide appears in the discharge curve of the flat primary battery 1. Therefore, there is a potential step between the potential of silver oxide near 1.56V, and for example, when the flat primary battery 1 is used in a watch, the operation of the crystal oscillator built in the watch becomes unstable, The progress of the watch may change.

  Moreover, it is preferable that mass ratio with respect to the positive mix 5 is 5 mass% or more and 10 mass% or less of the electrolyte solution accommodated in the accommodation recessed part 10 of the positive electrode can 2 and impregnating the positive mix 5. By adding the electrolytic solution within this range, the reaction between nickel oxyhydroxide and silver oxide can be facilitated to promote the formation of a silver / nickel composite oxide. When the mass ratio of the electrolytic solution is less than 5% by mass with respect to the positive electrode mixture 5, the reaction time until all the nickel oxyhydroxide reacts is several times that when the mass ratio is in the above range. There is a tendency to become longer. Alternatively, not all nickel oxyhydroxide can be reacted and unreacted nickel oxyhydroxide may remain. Moreover, when 10 mass% or more of electrolyte solution is added with respect to the positive electrode mixture 5, the liquid leakage property of the electrolyte solution from a battery tends to increase.

  Further, this electrolytic solution is preferably a sodium hydroxide aqueous solution having a concentration of 20 to 35% (w / v) or a potassium hydroxide aqueous solution having a concentration of 30 to 45% (w / v). When the concentration is within this range, the conductivity of the electrolytic solution in the battery after the silver / nickel composite oxide is formed is in a suitable range, and a battery having excellent closed circuit voltage characteristics and leakage resistance can be obtained. Further, when the electrolytic solution is produced by mixing a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution, it is preferable to mix a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution in the above concentration range.

  When the concentration of the electrolytic solution is less than the above range, since the viscosity of the electrolytic solution is insufficient, the electrolytic solution tends to flow in the positive electrode can, and as a result, liquid leakage tends to increase. Furthermore, when the concentration of the electrolytic solution is less than the above range, the reaction time between nickel oxyhydroxide and silver oxide tends to be long. Moreover, when the mass ratio of electrolyte solution exceeds the said range, the viscosity of electrolyte solution is too high, the absorptivity with respect to the positive mix 5 falls, and this also has the tendency for liquid-leakage property to increase.

  The surface of nickel oxyhydroxide is preferably coated with cobalt oxyhydroxide (CoOOH) having excellent conductivity. By coating the surface of nickel oxyhydroxide with cobalt oxyhydroxide, there is no need to add a conductive agent such as graphite that does not contribute to the discharge capacity into the positive electrode mixture, and a battery with excellent capacity can be obtained. It is because it can do.

  Next, a method for manufacturing the flat primary battery 1 will be described. When the positive electrode mixture 5 is formed, the nickel oxyhydroxide coated with cobalt oxyhydroxide and silver oxide have the above-mentioned mass ratio, mixed with the fluororesin powder as a binder in a blender, Mold into pellets with a tablet.

Further, the molded positive electrode mixture 5 is inserted into the positive electrode can 2, and an electrolytic solution is injected to cause the positive electrode mixture 5 to absorb the electrolytic solution. The concentration of the electrolytic solution at this time is within the above concentration range.
In addition, a separator 6 punched into a circular shape having a two-layer structure of a microporous membrane and a nonwoven fabric is loaded on the positive electrode mixture 5, and an alkaline electrolyte containing an aqueous potassium hydroxide solution is dropped to impregnate the separator 6.

  On the separator 6, a gel-like negative electrode mixture 7 containing zinc as a negative electrode active material is placed. Specifically, zinc alloy powder, zinc oxide, highly cross-linked sodium polyacrylate, carboxymethylcellulose, and an aqueous potassium hydroxide solution as an electrolyte are mixed to obtain negative electrode mixture 7. Then, the negative electrode can 3 and the positive electrode can 2 are sealed by caulking through the gasket 4.

  Next, the sealed flat primary battery 1 is stored for a preset reaction time to react nickel oxyhydroxide and silver oxide. The reaction time is about 600 to 700 hours at room temperature and about 50 hours at a temperature of 60 ° C. As a result, all of the nickel oxyhydroxide reacts with the silver oxide, leaving no unreacted nickel oxyhydroxide remaining.

Thus, by reacting nickel oxyhydroxide and silver oxide in the positive electrode can before using the battery, a silver / nickel composite oxide having a high processing cost can be produced at a low cost.
Next, examples in which the composition of the positive electrode mixture described above was variously changed were performed to verify the effects of the present invention.
Example 1
The mass ratio of the positive electrode mixture 5 was 40.0% by mass of nickel oxyhydroxide coated with γ-cobalt oxyhydroxide, 59.0% by mass of silver oxide, and 1.0% by mass of fluororesin powder as a binder. It was. Moreover, since the mass ratio of γ-cobalt oxyhydroxide with respect to nickel oxyhydroxide was 3 mass%, the mass ratio of nickel oxyhydroxide was 37.0 mass%.

After mixing these compositions with a blender, a pellet-shaped positive electrode mixture 5 having a mass of 140 mg was formed with a tableting machine.
And this positive electrode mixture 5 was accommodated in the positive electrode can, and 10 mg of 37% concentration potassium hydroxide aqueous solution was inject | poured into the positive electrode mixture 5, and it was made to absorb.

The mass ratio of the negative electrode mixture 7 was as follows: zinc alloy powder 64% by mass, zinc oxide 2.48% by mass, highly crosslinked sodium polyacrylate 0.66% by mass, carboxymethyl cellulose 2.04% by mass, 45% potassium hydroxide The aqueous solution was 30.80% by mass. Then, the negative electrode can 3 and the positive electrode can 2 were sealed by caulking through a gasket 4 and stored at a temperature of 60 ° C. for 50 hours to produce a flat primary battery 1.
(Example 2)
The content was 45% by mass of nickel oxyhydroxide and 54% by mass of silver oxide coated with cobalt oxyhydroxide (3% by mass). Other configurations were the same as those in Example 1.
(Example 3)
The content was 45% by mass of nickel oxyhydroxide and 54% by mass of silver oxide coated with cobalt oxyhydroxide (3% by mass). Further, the electrolytic solution absorbed in the positive electrode mixture 5 was set to 5 mass% with respect to the positive electrode mixture 5. Other configurations were the same as those in Example 1.
Example 4
The content was 45% by mass of nickel oxyhydroxide and 54% by mass of silver oxide coated with cobalt oxyhydroxide (3% by mass). In addition, the electrolytic solution absorbed in the positive electrode mixture 5 was 10 mass% with respect to the positive electrode mixture 5. Other configurations were the same as those in Example 1.
(Example 5)
The content was 45% by mass of nickel oxyhydroxide and 54% by mass of silver oxide coated with cobalt oxyhydroxide (3% by mass). Moreover, the electrolyte solution absorbed by the positive electrode mixture 5 was a potassium hydroxide aqueous solution having a concentration of 30%. Other configurations were the same as those in Example 1.
(Example 6)
The content was 45% by mass of nickel oxyhydroxide and 54% by mass of silver oxide coated with cobalt oxyhydroxide (3% by mass). Moreover, the electrolyte solution absorbed by the positive electrode mixture 5 was a potassium hydroxide aqueous solution having a concentration of 45%. Other configurations were the same as those in Example 1.
(Example 7)
The content was 45% by mass of nickel oxyhydroxide and 54% by mass of silver oxide coated with cobalt oxyhydroxide (3% by mass). Moreover, the electrolyte solution absorbed by the positive electrode mixture 5 was a sodium hydroxide aqueous solution having a concentration of 20%. Other configurations were the same as those in Example 1.
(Example 8)
The content was 45% by mass of nickel oxyhydroxide and 54% by mass of silver oxide coated with cobalt oxyhydroxide (3% by mass). Moreover, the electrolyte solution absorbed by the positive electrode mixture 5 was a sodium hydroxide aqueous solution having a concentration of 35%. Other configurations were the same as those in Example 1.
(Comparative Example 1)
The content was 59% by mass of nickel oxyhydroxide and 40% by mass of silver oxide coated with cobalt oxyhydroxide (3% by mass). Other configurations were the same as those in Example 1.
(Comparative Example 2)
The content was 59% by mass of nickel oxyhydroxide and 40% by mass of silver oxide coated with cobalt oxyhydroxide (3% by mass). The ratio of the electrolytic solution to the positive electrode mixture 5 was 1% by mass. Other configurations were the same as those in Example 1.
(Comparative Example 3)
The content was 59% by mass of nickel oxyhydroxide and 40% by mass of silver oxide coated with cobalt oxyhydroxide (3% by mass). Further, the ratio of the electrolytic solution to the positive electrode mixture 5 was set to 15% by mass. Other configurations were the same as those in Example 1.
(Comparative Example 4)
The content was 59% by mass of nickel oxyhydroxide and 40% by mass of silver oxide coated with cobalt oxyhydroxide (3% by mass). The electrolytic solution was a potassium hydroxide aqueous solution having a concentration of 25%. Other configurations were the same as those in Example 1.
(Comparative Example 5)
The content was 59% by mass of nickel oxyhydroxide and 40% by mass of silver oxide coated with cobalt oxyhydroxide (3% by mass). The electrolytic solution was a 50% potassium hydroxide aqueous solution. Other configurations were the same as those in Example 1.
(Comparative Example 6)
The content was 59% by mass of nickel oxyhydroxide and 40% by mass of silver oxide coated with cobalt oxyhydroxide (3% by mass). The electrolytic solution was a sodium hydroxide aqueous solution having a concentration of 15%. Other configurations were the same as those in Example 1.
(Comparative Example 7)
The content was 59% by mass of nickel oxyhydroxide and 40% by mass of silver oxide coated with cobalt oxyhydroxide (3% by mass). The electrolytic solution was a sodium hydroxide aqueous solution having a concentration of 40%. Other configurations were the same as those in Example 1.
<Verification>
And 130 alkaline batteries of above-mentioned Examples 1-8 and Comparative Examples 1-7 were produced, respectively, and the following verification was performed.

Specifically, the discharge capacity [mAh] when 20 of the produced batteries were each subjected to constant resistance discharge at 30 kΩ to a final voltage of 1.2 V is shown in the table of FIG.
The presence or absence of the discharge potential of nickel oxyhydroxide in the discharge curve obtained by constant resistance discharge is shown in the table of FIG.

Furthermore, 100 pieces of each of the batteries prepared were stored in a harsh environment at a temperature of 45 ° C. and a relative humidity of 93%, and the liquid leakage occurrence rates after 80 days and 100 days are shown in the table of FIG.
In addition, among the fabricated batteries, 10 batteries were each subjected to a closed circuit voltage (discharge characteristics) [V] after 7.8 ms under the conditions of DoD (discharge depth 80%) and load resistance 2 kΩ in an environment of −10 ° C. The results are shown in the table of FIG.

  Based on the table of FIG. 2, Examples 1-8 had a larger initial capacity than Comparative Examples 1-7. Moreover, while the discharge potential of nickel oxyhydroxide was seen in Comparative Examples 1-7, the discharge potential of nickel oxyhydroxide was not seen in Examples 1-8. This is because when the ratio of silver oxide is 1.2 times or more that of nickel oxyhydroxide, all of the nickel oxyhydroxide with a small capacity reacts with silver oxide, resulting in a high capacity silver / nickel composite oxidation. Because it became a thing.

  In Examples 3 to 4, in which the mass ratio of the potassium hydroxide aqueous solution was 5 mass% and 10 mass%, respectively, no leakage was observed, whereas the mass ratio of the potassium hydroxide aqueous solution was 15 mass%. In Comparative Example 3, leakage was observed. This is because when the electrolyte solution is injected in excess of 10% by mass, the positive electrode mixture 5 cannot absorb the electrolyte solution and the leakage resistance is lowered. Moreover, the comparative example 2 which made the mass ratio of potassium hydroxide aqueous solution 1 mass% had a low closed circuit voltage, and the discharge potential of the nickel oxyhydroxide was seen. This is because when the mass ratio of the electrolytic solution is less than 5% by mass, the reaction between nickel oxyhydroxide and silver oxide does not proceed smoothly and nickel oxyhydroxide remains.

  Further, in Examples 5 to 6 in which the concentration of the aqueous potassium hydroxide solution was 30% and 45%, respectively, no leakage was observed, whereas in Comparative Examples 4 to 5 in which the concentrations were 25% and 50%, respectively, Leakage was seen. That is, when the concentration is less than 30%, leakage occurs due to a viscosity that is too low with respect to the silver / nickel composite oxide. On the other hand, if the concentration exceeds 45%, the electrolyte solution cannot be absorbed in the positive electrode mixture due to a viscosity that is too high with respect to the silver / nickel composite oxide, resulting in leakage. Moreover, Examples 5-6 had a high closed circuit voltage compared with Comparative Examples 4-5. This is because suitable conductivity can be obtained by setting the concentration of the potassium hydroxide aqueous solution within the above range.

  Further, in Examples 7 to 8 in which the concentration of the aqueous sodium hydroxide solution was 20% and 35%, respectively, a higher closed circuit voltage was obtained than in Comparative Examples 6 to 7 in which the concentrations were 15% and 40%, respectively. This is because suitable conductivity can be obtained by setting the concentration of the sodium hydroxide aqueous solution within the above range.

According to the above embodiment, the following effects can be obtained.
(1) In the above embodiment, the positive electrode mixture 5 containing nickel oxyhydroxide and silver oxide is accommodated in the positive electrode can 2, and the nickel oxyhydroxide and silver oxide are reacted in the positive electrode can to produce silver / silver A nickel composite oxide was produced. Moreover, since the mass ratio of silver oxide is 1.2 (times) or more with respect to nickel oxyhydroxide, all nickel oxyhydroxide can be reacted with silver oxide in the positive electrode can before using the battery. it can. Therefore, the flat primary battery 1 having a high volume energy density and excellent discharge potential flatness can be produced at low cost.

  (2) In the said embodiment, the ratio of electrolyte solution was 5 mass% or more with respect to the positive mix 5 and 10 mass% or less. For this reason, while making the reaction of silver oxide and nickel oxyhydroxide smooth, leak-proof property can be improved.

  (3) In the said embodiment, electrolyte solution is potassium hydroxide aqueous solution, Comprising: The density | concentration is 30% or more and 45% or less. For this reason, while making the reaction of silver oxide and nickel oxyhydroxide smooth, battery characteristics and leakage resistance can be improved.

  (4) In the said embodiment, electrolyte solution is sodium hydroxide aqueous solution, Comprising: The density | concentration is 20% or more and 35% or less. For this reason, while making the reaction of silver oxide and nickel oxyhydroxide smooth, battery characteristics and leakage resistance can be improved.

  DESCRIPTION OF SYMBOLS 1 ... Flat primary battery, 2 ... Positive electrode can, 3 ... Negative electrode can, 4 ... Gasket, 5 ... Positive electrode mixture, 6 ... Separator, 7 ... Negative electrode mixture.

Claims (5)

In the method for producing a flat primary battery containing the positive electrode mixture in the positive electrode can,
The positive electrode mixture containing nickel oxyhydroxide and silver oxide is accommodated in the positive electrode can together with an electrolytic solution, and the nickel oxyhydroxide and the silver oxide are reacted in the positive electrode can, thereby producing a silver / nickel composite. Producing oxides,
A method for producing a flat primary battery, wherein a mass ratio of the silver oxide is 1.2 or more with respect to the nickel oxyhydroxide. In the manufacturing method of the flat primary battery according to claim 1,
A method for producing a flat primary battery, wherein a ratio of the electrolytic solution is 5% by mass or more and 10% by mass or less with respect to the positive electrode mixture. In the manufacturing method of the flat primary battery according to claim 1 or 2,
The method for manufacturing a flat primary battery, wherein the electrolytic solution is an aqueous potassium hydroxide solution and has a concentration of 30% to 45%. In the manufacturing method of the flat primary battery according to claim 1 or 2,
The method for producing a flat primary battery, wherein the electrolytic solution is an aqueous solution of sodium hydroxide and has a concentration of 20% to 35%.   The flat primary battery manufactured with the manufacturing method of any one of Claims 1-4.

Images