JP2000251883A - Sealed alkaline zinc storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce decrease of a discharge capacity in a charge-discharge cycle, cause of battery internal pressure increased and leakage of an alkaline electrolyte hardly generated, and carry out manufacture of high yield. SOLUTION: This battery is a sealed alkaline zinc storage battery, wherein a negative electrode using zinc as an active material is arranged inside a cylinder of a cylindrical positive electrode via a separator, and of which the power generating element body comprising the positive electrode, the negative electrode, an alkaline electrolyte, the separator and a negative electrode current collecting body occupies 75% of a battery can inner volume. A positive active material is a solid solution powder in which 5-50 atom % of manganese based on total amount of the manganese and nickel is solid-dissolved in γ-nickel oxyhydroxide, powder of specified manganese oxide is added to the solid solution powder, and a positive electrode is a molding formed by pressing a mixture containing the solid-solution powder, the powder of the manganese oxide and a conductive agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a negative electrode having a gamma-type nickel oxyhydroxide as an active material, in which a negative electrode is disposed via a separator in a cylindrical positive electrode. , An alkaline electrolyte, the separator, and a negative electrode current collector. The power generation element body occupies 75% or more of the internal volume of the battery can. The present invention relates to improvement of a positive electrode for the purpose of providing a sealed alkaline zinc storage battery in which a decrease in discharge capacity is small, a rise in battery internal pressure or leakage of an alkaline electrolyte does not easily occur, and which can be manufactured with good yield. Here, the discharge-started battery refers to a battery that can be discharged for the first time without being charged in advance.

[0002]

2. Description of the Related Art
Manganese dioxide has been proposed as a positive electrode active material of a sealed alkaline zinc storage battery using zinc as an active material (see Japanese Patent Publication No. 45-3570). Also, a mixture of nickel oxide and manganese dioxide has been proposed as a positive electrode active material of a nickel-zinc primary battery using zinc as a negative electrode active material (see JP-A-49-114741).

However, in an alkaline storage battery using manganese dioxide as a positive electrode active material, the reversibility of the manganese dioxide in the charge / discharge cycle is poor. Decreases sharply. Since manganese dioxide has a small oxygen overvoltage, oxygen is generated due to electrolysis of water on the positive electrode side during charging, and the internal pressure of the battery increases (4OH ⁻ ⇒O
₂ + 2H ₂ O + 4e ⁻ ), and the adhesion at the joint of the battery exterior member is reduced accordingly, so that the alkaline electrolyte easily leaks.

Also, nickel oxide has a small oxygen overpotential like manganese dioxide. Therefore, when a mixture of nickel oxide and manganese dioxide is used as a positive electrode active material of a storage battery, the internal pressure of the battery rises during charging and the alkaline The electrolyte is easy to leak.

[0005] As described above, any of the positive electrode active materials has a problem as a positive electrode active material for a sealed alkaline zinc storage battery. Such an increase in the internal pressure of the battery at the time of charging and the associated liquid leakage are particularly problematic in a sealed alkaline zinc storage battery in which the ratio of the space in the battery can is small.

Recently, a sealed alkaline zinc storage battery having a negative electrode arranged in a cylindrical positive electrode (molded body) via a separator (hereinafter, a sealed alkaline zinc storage battery of this structure,
This is referred to as "inside-out type battery". Γ-type nickel oxyhydroxide has been proposed as the positive electrode active material of (1). In this inside-out type battery, since it is necessary to make the outer peripheral surface of the cylindrical positive electrode adhere to the inner peripheral surface of the battery can, a cylindrical positive electrode having an outer size slightly larger than the inner size of the battery can is produced. The positive electrode is inserted into the battery can while compressing and shrinking the outer peripheral surface of the positive electrode.When γ-type nickel oxyhydroxide is used as the positive electrode active material, cracks occur in the molded body during insertion, causing damage. Easy to do. That is, the inside-out type battery has a problem that the yield of battery manufacturing is not good.

Accordingly, the present invention provides an inside-out type discharge start which can be manufactured with good yield with a small decrease in discharge capacity in a charge / discharge cycle, a small increase in the internal pressure of the battery and no leakage of the alkaline electrolyte. It is intended to provide a battery.

[0008]

In a sealed alkaline zinc storage battery according to the present invention (battery of the present invention), a negative electrode containing zinc as an active material is disposed in a cylindrical positive electrode via a separator. And a negative electrode is disposed via a separator in a cylindrical positive electrode tube using γ-type nickel oxyhydroxide as an active material, and the positive electrode, the negative electrode, an alkaline electrolyte, In a sealed alkaline zinc storage battery in which a power generating element composed of a separator and a negative electrode current collector occupies 75% or more of the internal volume of the battery can, the active material of the positive electrode is γ-type nickel oxyhydroxide, manganese is manganese, Is a solid solution powder having a solid solution of 5 to 50 at% based on the total amount of nickel and nickel, and the solid solution powder is selected from the group consisting of manganese monoxide, trimanganese tetroxide, dimanganese trioxide and γ-type manganese dioxide. Wherein at least one manganese oxide powder is added, and the positive electrode is formed by pressure molding a mixture containing the solid solution powder, the manganese oxide powder, and a conductive agent. It is characterized by being a body.

The positive electrode active material is a solid solution powder in which manganese is dissolved in γ-type nickel oxyhydroxide. Oxygen overvoltage of the positive electrode increases due to solid solution of manganese in γ-type nickel oxyhydroxide. The amount of solid solution of manganese (hereinafter referred to as “manganese solid solution rate”) is determined by manganese and nickel (γ
(Nickel in type nickel oxyhydroxide) based on the total amount. The reason for this is that if the manganese solid solution rate is less than 5 atomic%, the oxygen overvoltage of the positive electrode does not become sufficiently large, so that liquid leakage easily occurs, while the manganese solid solution rate exceeds 50 atomic%. In this case, the filling amount of the γ-type nickel oxyhydroxide, which is the positive electrode active material, is reduced, so that a sufficient battery capacity cannot be obtained.

As the γ-type nickel oxyhydroxide, those having a valence of nickel in a fully charged state of 3.4 to 3.8 are preferable. With a β-type nickel oxyhydroxide having a valence of nickel of less than 3.4 in a fully charged state, a sufficient battery capacity cannot be obtained. Further, since β-nickel oxyhydroxide has a small oxygen overvoltage, liquid leakage easily occurs during charging. It should be noted that there is no γ-type nickel oxyhydroxide in which the valence of nickel in a fully charged state exceeds 3.8. Even if the battery is further charged after being fully charged, that is, overcharged, only water is decomposed and oxygen is generated, and the valence of nickel does not exceed 3.8.

[0011] The γ-type nickel oxyhydroxide is obtained, for example, by oxidizing nickel hydroxide with an oxidizing agent such as sodium hypochlorite (NaClO). The valence of nickel of the γ-type nickel oxyhydroxide can be adjusted by adjusting the amount of the oxidizing agent. The solid solution powder is
It is obtained by using nickel hydroxide in which manganese is dissolved in place of nickel hydroxide. Nickel hydroxide in which manganese is dissolved is obtained by adjusting the pH to 9 to 12 by adding an alkali to an aqueous solution containing a manganese salt and a nickel salt, and then mixing for a predetermined time (alkali coprecipitation method). Can be

As a solid solution powder, besides manganese, zinc, cobalt, bismuth, aluminum and rare earth elements (yttrium, erbium, ytterbium,
And at least one element selected from the group consisting of gadolinium) as a solid solution element. The solid solution of these elements further increases the oxygen overvoltage of the positive electrode.

In the present invention, the above-mentioned solid solution powder is
At least one manganese oxide powder selected from the group consisting of manganese monoxide, trimanganese tetraoxide, dimanganese trioxide and γ-type manganese dioxide is added. The addition of these specific manganese oxide powders increases the strength of the obtained positive electrode, suppresses the occurrence of cracks when the positive electrode is inserted into the battery can, and improves the battery production yield. It is not clear why the strength of the positive electrode increases,
It is considered that the above manganese oxide functions as a binder during pressure molding.

The amount of the manganese oxide powder added to the solid solution powder varies depending on the type of the manganese oxide. γ
When manganese dioxide is added, the weight ratio of the solid solution powder to the gamma manganese dioxide powder is 99: 1 to 65: 3.
5 must be added. When the addition ratio of the γ-type manganese dioxide powder is less than the above range, the strength of the positive electrode cannot be sufficiently improved, while when the addition ratio of the γ-type manganese dioxide powder is more than the above range, the solid solution powder , The battery capacity is reduced.

The positive electrode is obtained by mixing the above-mentioned solid solution powder, the above-mentioned manganese oxide powder, a conductive agent, and an alkaline electrolyte, and pressing the mixture into a cylindrical shape. Examples of the conductive agent include graphite.

The present invention is directed to a sealed alkaline zinc storage battery in which a power generating element composed of a positive electrode, a negative electrode, an alkaline electrolyte, a separator, and a negative electrode current collector occupies 75% or more of the internal volume of a battery can. This is because, in such a high-density sealed alkaline zinc storage battery, the internal pressure of the battery is particularly likely to increase, and the alkaline electrolyte is likely to leak when charge and discharge are repeated.

As described above, in the battery of the present invention, since a predetermined amount of manganese is dissolved in γ-type nickel oxyhydroxide, the oxygen overvoltage of the positive electrode is large. Further, since the positive electrode contains manganese oxide, the strength is high.

[0018]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples, and can be carried out by appropriately changing the scope without changing the gist. It is something.

(Experiment 1) A battery of the present invention and a comparative battery were prepared, and a battery capacity (discharge capacity in the first cycle), a capacity retention rate, the number of leaked batteries, and a battery in which a positive electrode was inserted into a battery can were generated. I checked the number.

(Preparation of Battery (A1) of the Present Invention) A battery (A1) of the present invention was prepared by the following procedure.

[Preparation of positive electrode] Manganese sulfate (MnS
O ₄ ) 40.4 g and nickel sulfate (NiSO ₄ ) 15
To 5,000 ml of the 4.8 g aqueous solution was added dropwise a mixed aqueous solution of 10 wt% aqueous ammonia and 10 wt% aqueous sodium hydroxide at a weight ratio of 1: 1 to adjust the pH to 9.5 ± 0.3. After the pH becomes constant, stir and mix for 1 hour,
After filtration, washing with water and drying at 80 ° C., a nickel hydroxide powder in which manganese was dissolved in solid solution was prepared. The manganese solid solution rate of the produced nickel hydroxide powder was determined by atomic absorption analysis, and was 20%.

Next, 100 g of the above nickel hydroxide powder in which manganese was dissolved in a solid solution was added to a mixed solution of 500 ml of a 10 mol / l aqueous solution of sodium hydroxide and 1500 ml of a 10% by weight aqueous solution of sodium hypochlorite while stirring. After stirring and mixing for 1 hour, the resulting precipitate was filtered off, washed with water, and dried at 60 ° C. to obtain a solid solution powder in which manganese was dissolved in γ-type nickel oxyhydroxide (γ-NiOOH). Was. The manganese solid solution rate of this solid solution powder was 20% as determined by atomic absorption analysis. Also,
The valence of nickel of this solid solution powder was 3.6 as determined by a divalent / trivalent redox titration method of iron. The manganese solid solution rate and the valence of nickel in the following experiments were all determined by atomic absorption spectrometry and divalent / trivalent iron redox titration.

The above solid solution powder and γ-type manganese dioxide (γ-MnO ₂ ) powder are mixed at a weight ratio of 95: 5, and 100 parts by weight of the obtained mixed powder and 10 parts by weight of graphite powder as a conductive agent are mixed. , 30% by weight aqueous solution of potassium hydroxide 10
Parts by weight and mixed with a grinder for 30 minutes, molded under pressure to form an outer diameter of 1.3 cm, an inner diameter of 0.85 cm, and a height of 1.1.
A cylindrical molded body of 5 cm was produced. In the production of the battery, three cylindrical molded bodies were joined in series and used as one cylindrical positive electrode as a whole.

[Preparation of Negative Electrode] A solution containing 65 parts by weight of zinc powder as a negative electrode active material and a saturated amount of zinc oxide (ZnO)
34 parts by weight of a 0% by weight aqueous solution of potassium hydroxide and 1 part by weight of polyacrylic acid (product code "Junron PW150" manufactured by Nippon Pure Chemical Co., Ltd.) as a gelling agent were mixed to prepare a gelled negative electrode. .

[Preparation of Battery] An AA size inside-out type battery (battery of the present invention) (A1) was prepared using the above positive electrode and negative electrode. In order to control the battery capacity by the positive electrode capacity, the electrochemical capacity between the positive electrode and the negative electrode was set to 1: 1.2 (all of the following batteries had the same capacity ratio). In addition, the volume ratio of the power generating element body including the positive electrode, the negative electrode, the alkaline electrolyte, the separator, and the negative electrode current collector to the internal volume of the battery can (the volume of the inner portion of the insulating packing) was set to 80%. (The same ratio was set to 80% for the following batteries.)

FIG. 1 is a sectional view of the manufactured inside-out type battery. The illustrated inside-out type battery (A
1) a cylindrical battery can (bottom external terminal) 1, a battery cover (negative terminal outside) 2, an insulating packing 3, a brass negative electrode current collecting rod 4, a cylindrical positive electrode (nickel electrode) 5, vinylon , A gelled negative electrode (zinc electrode) 7 and the like.

The positive electrode 5 is housed in the battery can 1 with the outer peripheral surface of the cylinder in contact with the inner peripheral surface of the battery can 1, and the outer peripheral surface is in contact with the inner peripheral surface of the positive electrode 5. A cylindrical separator film 6 is pressed against the inside, and the inside of the separator film 6 is filled with a gelled negative electrode 7. At the center of the circular cross section of the negative electrode 7, a negative electrode current collector rod 4 whose one end is supported by an insulating packing 3 that electrically insulates the battery can 1 from the battery lid 2 is inserted. The opening of the battery can 1 is closed by a battery cover 2. The battery is hermetically sealed by inserting an insulating packing 3 into the opening of the battery can 1, placing the battery lid 2 thereon, and caulking the open end of the battery can inward.

(Preparation of Battery (A2) of the Present Invention) The method of preparing the battery (A1) of the present invention was the same as that of the battery (A1) except that the amount of manganese sulfate used was 10.2 g instead of 40.4 g. Similarly, the battery of the present invention (A2) was produced. The manganese solid solution rate of the solid solution powder used for the positive electrode was 5
%Met.

(Preparation of Battery (A3) of the Present Invention) The method of preparing the battery (A1) of the present invention was the same as that of the battery (A1) except that the amount of manganese sulfate used was changed to 20.2 g instead of 40.4 g. Similarly, the battery (A3) of the present invention was produced. The manganese solid solution rate of the solid solution powder used for the positive electrode was 1
It was 0%.

(Preparation of Battery (A4) of the Present Invention) The preparation of the positive electrode was performed in the same manner as in the preparation of the battery (A1) of the present invention except that the amount of manganese sulfate used was changed to 101 g instead of 40.4 g. Thus, a battery (A4) of the present invention was produced.
The manganese solid solution rate of the solid solution powder used for the positive electrode was 50%.
Met.

(Preparation of Comparative Battery (B1)) The preparation of the positive electrode was carried out in the same manner as in the preparation of the battery (A1) of the present invention except that the amount of manganese sulfate used was changed to 5.1 g instead of 40.4 g. Thus, a comparative battery (B1) was produced. The manganese solid solution rate of the solid solution powder used for the positive electrode was 2.5%.
Met.

(Preparation of Comparative Battery (B2)) The preparation of the positive electrode was performed in the same manner as in the preparation of the battery (A1) of the present invention except that the amount of manganese sulfate used was changed to 121 g instead of 40.4 g. A comparative battery (B2) was produced. The manganese solid solution rate of the solid solution powder used for the positive electrode was 60%.

(Preparation of Comparative Battery (B3)) A comparative battery (B3) was prepared in the same manner as the battery (A1) of the present invention except that γ-type manganese dioxide powder was not added to the solid solution powder. B3) was prepared.

(Preparation of Comparative Battery (B4)) 100 g of γ-type manganese dioxide powder, 15 g of graphite powder and 5 g of polyethylene resin were mixed, and the obtained mixture was mixed with 20 ml of a 7 mol / liter aqueous solution of potassium hydroxide. Then, pressure molding was performed to produce a cylindrical positive electrode. Except that this positive electrode was used as a cylindrical positive electrode, the battery of the present invention (A1)
The comparative battery (B4) was produced in the same manner as in the production method described above.

(Preparation of Comparative Battery (B5)) 500 ml of a 2 mol / l aqueous solution of nickel nitrate and 1500 ml of a 10% by weight aqueous solution of sodium hypochlorite were dropped and mixed into 2000 ml of a 14 mol / l aqueous solution of potassium hydroxide. Thereafter, the mixture was gradually cooled for 1 hour. Next, the formed precipitate was separated by filtration, washed with water, and dried at 90 ° C. to prepare a nickel oxide powder as a positive electrode active material. 50 g of the prepared nickel oxide powder and 30 gamma-type manganese dioxide powder
g, graphite 15g and polyethylene resin 5g,
20 ml of a 7 mol / l aqueous solution of potassium hydroxide was mixed with the obtained mixture, and the mixture was molded under pressure to produce a cylindrical positive electrode. Except for using this positive electrode as a cylindrical positive electrode, the same method as in the method for producing the battery (A1) of the present invention was applied.
A comparative battery (B5) was produced.

<Number of Cells in Which Cracks Occur When Inserting Positive Electrode> With respect to 10 batteries, the presence or absence of cracks when the positive electrode was inserted into the battery can was visually observed to determine the number of cells in which cracks occurred. Table 1 shows the results. The fractional numerator in the column of the number of cracking batteries in Table 1 is the number of batteries in which cracks occurred when the positive electrode was inserted.

<Discharge capacity, capacity retention rate and number of leaked batteries>
After discharging each battery to 10 V at 100 mA to 1 V, charging and discharging at 100 mA until reaching 1.95 V were performed for 25 cycles, and the discharge capacity at the first cycle, the capacity retention rate at the 25th cycle, and The number of leaked batteries at the 25th cycle was examined. Table 1 shows the results. The numerator of the fraction in the column of the number of leaked batteries in Table 1 is the number of batteries that leaked.
The discharge capacity at the first cycle in Table 1 indicates the battery of the present invention (A
This is an index when the discharge capacity in the first cycle of 1) is 100. The capacity retention rate is a ratio (%) of the discharge capacity at the 25th cycle to the discharge capacity at the first cycle of each battery, and is an average value of the capacity retention rates of the batteries in which the electrolyte did not leak.

[0038]

[Table 1]

As shown in Table 1, the batteries (A1) to (A4) of the present invention in which the manganese solid solution ratio of the solid solution powder used for the positive electrode was 5 to 50%, had a high capacity retention ratio and the number of leaked batteries Is 0 (zero), and the number of crack generating batteries is 0 (zero). On the other hand, in the comparative battery (B1) having a manganese solid solution rate of 2.5%, the capacity retention rate was as low as 80%, and liquid leakage occurred in 5 of the 10 batteries at the 25th cycle. In the comparative battery (B2) having a manganese solid solution rate of 60%, the discharge capacity in the first cycle was as small as 85. The reason why the capacity retention rate of the comparative battery (B1) is low and the number of the leaky batteries is large is that the solid solution powder used for the positive electrode has a manganese solid solution rate that is too low, so that the oxygen overvoltage of the positive electrode can be sufficiently increased. Because there was no. Further, the reason why the discharge capacity in the first cycle of the comparative battery (B2) is small is that the filling amount of γ-nickel oxyhydroxide, which is a positive electrode active material, is reduced by an increase in the solid solution amount of manganese. The reason why the number of crack generating batteries of the comparative battery (B3) is large is that the strength of the positive electrode was low because γ-type manganese dioxide was not added to γ-nickel oxyhydroxide. The reason why the capacity retention ratio of the comparative battery (B4) is low is that the crystal structure having tunnel-like vacancies of γ-type manganese dioxide has collapsed. This is because the overvoltage is extremely small. Comparative battery (B5)
The reason why the discharge capacity in the first cycle is small is that the oxygen overvoltage of the positive electrode is small, oxygen is generated on the positive electrode side, and the active material utilization rate decreases, and the capacity retention rate is low.
The reason for the large number of leaked batteries is that oxygen was generated on the positive electrode side during charging because the oxygen overvoltage of the positive electrode was small.

(Experiment 2) The amount of the γ-type manganese dioxide powder added when the γ-type manganese dioxide powder was added to the solid solution powder was examined.

In the preparation of the positive electrode, the weight ratio of the solid solution powder and the γ-type manganese dioxide powder was 99.5: 0.5, 99: 1, 90:10, 80: 2 instead of 95: 5.
0, 70:30, 65:35 and 62.5: 37.5
The batteries (X1) to (X7) were sequentially manufactured in the same manner as in the method of manufacturing the battery (A1) of the present invention except that they were mixed.
Was prepared.

A charge / discharge cycle test was performed on the 10 batteries under the same conditions as those used in Experiment 1, and the number of cracked batteries when each battery was inserted into the positive electrode, the discharge capacity at the first cycle, and the capacity maintenance at the 25th cycle The ratio and the number of leaked batteries at the 25th cycle were examined. Table 2 shows the results. Table 2 also shows the results of the battery (A1) of the present invention. The discharge capacity at the first cycle in Table 2 is an index with the discharge capacity at the first cycle of the battery (A1) of the present invention being 100. Further, the capacity retention rate is 25% of the discharge capacity of the first cycle of each battery.
It is the ratio (%) of the discharge capacity at the cycle and the average value of the capacity retention ratio of the battery in which the electrolyte did not leak.

[0043]

[Table 2]

As shown in Table 2, manganese oxide powder γ
When the manganese dioxide powder is used, the weight ratio between the solid solution powder and the γ-type manganese dioxide powder is 99: 1 to 6
It is understood that it is necessary to add γ-type manganese dioxide powder so that the ratio becomes 5:35.

(Experiment 3) The type of manganese oxide powder added to the solid solution powder was examined.

As the manganese oxide powder to be added to the solid solution powder, instead of γ-type manganese dioxide powder, manganese monoxide, trimanganese tetroxide, dimanganese trioxide, β-type manganese dioxide (β-MnO ₂ ) (γ Manganese dioxide was prepared by firing at 450 ° C.) and manganese carbonate (MnCO ₃ ) in the same manner as the battery (A1) except that the respective powders were added. (Y1) to (Y5) were produced. The weight ratio between the solid solution powder and each manganese oxide powder was 95: 5.

A charge / discharge cycle test was performed on the ten batteries, under the same conditions as those used in Experiment 1, and the discharge capacity at the first cycle, the capacity retention at the 25th cycle,
The number of leaked batteries in the fifth cycle and the number of cracked batteries when the positive electrode was inserted were examined. Table 3 shows the results. Table 3 also shows the results of the battery (A1) of the present invention. The discharge capacity at the first cycle in Table 3 is an index with the discharge capacity at the first cycle of the battery (A1) of the present invention being 100. The capacity retention ratio is the ratio (%) of the discharge capacity at the 25th cycle to the discharge capacity at the first cycle of each battery.
This is the average value of the zero capacity retention rates.

[0048]

[Table 3]

As shown in Table 3, in order to increase the strength of the positive electrode,
As the manganese oxide, it is necessary to use any one of manganese monoxide, trimanganese tetroxide, dimanganese trioxide and γ-type manganese dioxide, and β-type manganese dioxide and manganese carbonate cannot increase the strength of the positive electrode. You can see that. For the batteries (Y4) and (Y5), the number of crack-producing batteries when the positive electrode was inserted was extremely large.

(Experiment 4) The relationship between the valence of nickel in the solid solution powder and the battery characteristics was examined.

In the preparation of the positive electrode, the amount of the 10% by weight aqueous sodium hypochlorite solution to be mixed with 500 ml of the aqueous sodium hydroxide solution was changed to 1500 ml, and
Batteries Z1 to Z3 were produced in the same manner as the method of producing battery (A1) of the present invention except that the amounts were 350 ml, 1400 ml, and 1600 ml. The valence of nickel of the solid solution powder used for each battery was 3.3, 3.4, and 3.8, respectively.
Met.

A charge / discharge cycle test was performed on the ten batteries under the same conditions as those used in Experiment 1, and the discharge capacity at the first cycle, the capacity retention at the 25th cycle,
The number of leaked batteries at the fifth cycle was examined. Table 4 shows the results. Table 4 also shows the results of the battery (A1) of the present invention. The discharge capacity at the first cycle in Table 4 is an index with the discharge capacity at the first cycle of the battery (A1) of the present invention being 100. The capacity retention rate is a ratio (%) of the discharge capacity at the 25th cycle to the discharge capacity at the first cycle of each battery, and is an average value of the capacity retention rates of the batteries in which the electrolyte did not leak. The number of cracking batteries when the positive electrode was inserted was 0 (zero) in each case.

[0053]

[Table 4]

According to Table 4, in order to obtain a battery having a large discharge capacity in the first cycle, a solid solution powder having a valence of nickel in a fully charged state of 3.4 to 3.8 is used as a positive electrode active material. It turns out that it is preferable. The battery (Z
The reason why the number of the liquid leakage batteries in 1) is large is that the nickel oxyhydroxide in the solid solution is a β-type nickel oxyhydroxide having a small oxygen overvoltage.

[0055]

According to the present invention, there is provided a sealed alkaline zinc storage battery in which a decrease in discharge capacity in a charge / discharge cycle is small, a rise in the internal pressure of the battery or a leakage of an alkaline electrolyte does not easily occur, and which can be manufactured with a high yield.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an inside-out type battery manufactured in an example.

[Explanation of symbols]

 A1 Inside-out type battery 1 Battery can (external terminal of positive electrode) 2 Battery cover (external terminal of negative electrode) 3 Insulating packing 4 Negative current collector rod 5 Cylindrical positive electrode (nickel electrode) 6 Cylindrical separator film 7 Gelled negative electrode (zinc electrode) )

Continued on the front page (72) Inventor Mamoru Kimoto 2-5-5 Keihanhondori, Moriguchi City, Osaka Prefecture Inside Sanyo Electric Co., Ltd. (72) Inventor Yasuhiko Ito 2-5-5 Keihanhondori, Moriguchi City, Osaka Prefecture No. Sanyo Electric Co., Ltd. (72) Inventor Koji Nishio 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term (reference) 5H003 AA04 AA08 BA03 BA05 BB02 BB04 BB14 BB15 BC01 BD00 BD03 BD04 5H016 AA02 AA05 AA08 AA10 BB05 EE01 EE04 EE05 HH00 HH01 HH06 5H028 AA05 AA07 BB04 BB06 EE01 EE04 EE05 EE08 HH00 HH01 HH05

Claims (4)

[Claims] A negative electrode comprising zinc as an active material is disposed in a cylindrical positive electrode via a separator, and said positive electrode, said negative electrode, an alkaline electrolyte, said separator, In a sealed alkaline zinc storage battery in which a power generating element composed of a negative electrode current collector occupies 75% or more of the internal volume of a battery can, the active material of the positive electrode is γ-type nickel oxyhydroxide, manganese is manganese and nickel. based on the total amount, it is from 5 to 50 atomic% solid solution solid solution powder, to the solid-solution powder, manganese monoxide (MnO), trimanganese tetraoxide (Mn ₃ O _4), manganese sesquioxide (Mn ₂ O ₃ )
And at least one manganese oxide powder selected from the group consisting of manganese dioxide (γ-MnO ₂ ) and the positive electrode, wherein the positive electrode comprises the solid solution powder and the manganese oxide powder. , A mixture containing a conductive agent,
A sealed alkaline zinc storage battery characterized in that it is a molded body formed by pressure molding. 2. The sealed alkali according to claim 1, wherein the manganese oxide is γ-type manganese dioxide, and the weight ratio between the solid solution powder and the γ-type manganese dioxide powder is 99: 1 to 65:35. Zinc battery. 3. The sealed alkaline zinc storage battery according to claim 1, wherein the valence of nickel in the fully charged state of the γ-type nickel oxyhydroxide is 3.4 to 3.8. 4. The closed mold according to claim 1, wherein said solid solution powder further contains at least one element selected from the group consisting of zinc, cobalt, bismuth, aluminum and rare earth elements as a solid solution element. Alkaline zinc storage battery.