JP2754864B2 - Manufacturing method of zinc alkaline battery - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mercury-free technology for zinc-alkaline batteries using zinc as a negative electrode active material, an aqueous alkaline solution as an electrolyte, and manganese dioxide, silver oxide, oxygen, etc. as a positive electrode active material. The present invention relates to a method for producing a zinc alkaline battery which is pollution-free and has excellent storage properties and discharge performance.

2. Description of the Related Art Approximately ten years ago, there has been a strong concern that environmental pollution due to mercury in waste batteries has become a concern, and research has been conducted on reducing the amount of mercury in alkaline dry batteries. As a result, with the development of corrosion-resistant zinc alloys and the like, the amount of mercury contained in alkaline dry batteries is currently being reduced to 250 ppm based on the battery weight. However, today, there is a concern about environmental destruction caused by industrial products worldwide, as represented by the problem of ozone depletion due to chlorofluorocarbons, and there is a growing demand for completely eliminating mercury in alkaline dry batteries.

The approach to the mercury-free alkaline dry battery technology was made at the time when the alkaline dry battery to which mercury was added was developed. An announcement has been made.

Problems to be Solved by the Invention In a battery in which pure zinc is used as the active material of the negative electrode without mercury silver, a corrosion reaction accompanied by hydrogen generation of zinc occurs violently,
There is a problem that the internal pressure of the battery is increased and the electrolytic solution is pushed to the outside, and the resistance to liquid leakage is reduced.

In a partially discharged battery, the hydrogen generation rate of the zinc negative electrode is accelerated, and the leak resistance is further reduced. These are attributable to the fact that by increasing the hydrogen overpotential on the zinc surface, mercury that suppressed the corrosion reaction disappeared.

Even if a corrosion-resistant zinc alloy containing indium, aluminum, and lead, which has been proven to have a corrosion-resistant effect by reducing mercury in zinc corrosion, is used as a mercury-free battery, it is not possible to ensure the battery's liquid leakage resistance after partial discharge.

In addition, a commercially available battery formed by adding indium oxide or indium hydroxide to a gel negative electrode using pure zinc powder as an active material of the negative electrode is also a practical battery in the same manner as the battery formed only of the corrosion-resistant alloy described above. Cannot ensure liquid leakage resistance.

Furthermore, even if a battery is formed by adding an amine-based surfactant that is effective in reducing mercury as an organic inhibitor to a gel negative electrode using a corrosion-resistant zinc alloy containing indium, aluminum, and lead as an active material of the negative electrode, The liquid resistance of the battery after the partial discharge cannot be ensured.

As described above, each of the conventional sheaths does not have a perfect corrosion inhibiting effect, and cannot be said to be practical at least for sealed batteries.

In realizing the realization of mercury-free alkaline batteries, the present inventors have proposed a corrosion-resistant zinc alloy, a combined effect of an inorganic inhibitor and an organic inhibitor,
The materials that can exert the best effect and their optimal conditions and concentrations were studied.

Means for Solving the Problems First, the configuration of the present invention regarding the combined use of a corrosion-resistant zinc alloy and an inorganic inhibitor will be described. The gelled negative electrode in the present invention is an active material comprising a corrosion-resistant zinc alloy powder in which an appropriate combination of any of indium, lead, bismuth, calcium, and aluminum is added to zinc, and an inorganic inhibitor. And a gel-like alkaline electrolyte in which a sulfide of an alkali metal is dissolved at an appropriate concentration.

The above-mentioned corrosion-resistant zinc alloy contains 0.01 to 1 wt% of indium.
%, One or two of lead and bismuth in total 0.005
0.5% by weight of zinc alloy or indium
1 to 1 wt%, one or two types of lead and bismuth in total
It is a zinc alloy containing 0.005 to 0.5 wt% and one or two kinds of calcium and aluminum in total of 0.005 to 0.2 wt%. The appropriate addition amount of the sulfide of the alkali metal is 0.005 to 0.5% by weight based on the zinc alloy.

Next, the configuration of the present invention regarding the combined use of a zinc alloy, an inorganic inhibitor and an organic inhibitor will be described.
The gelled negative electrode of the present invention comprises a corrosion-resistant zinc alloy powder in which indium, lead, bismuth, calcium, and aluminum are added in an appropriate amount in an appropriate combination, and a sulfide of an alkali metal having an appropriate concentration as an inorganic inhibitor. And a gel-like alkaline electrolyte to which an appropriate amount of a surfactant having polyethylene oxide as an organic inhibitor in a hydrophilic portion and having a fluorinated alkyl group in a lipophilic portion is added.

The above surfactant is used in an amount of 0.01 to 0.1 wt.
% In the alkaline electrolyte is effective.

The corrosion-resistant zinc alloy contains 0.01 to 1 wt% of indium,
0.005 to 0.5 in total of one or two of lead and bismuth
wt% containing zinc alloy or indium 0.01-1w
t%, one or two of lead and bismuth in total 0.005
It is a zinc alloy containing about 0.5 wt% and one or two kinds of calcium and aluminum in total of 0.005 to 0.2 wt%.

The sulfides of alkali metals are lithium sulfide, lithium lithium sulfide, sodium sulfide, sodium polysulfide, potassium sulfide, potassium potassium sulfide, and rubidium sulfide.
0.5 wt%.

Also, the surfactant is represented by the following structural formula _{(X) -C n F 2n -} (Y) - (CH 2 CH 2 0) m - (Z) X: -H or -F Y: -CONH- or -SO ₂ NR- {R represents an alkyl _{group} Z: -CH 3, -P0 3} W 2 or -SO ₃ W {W alkali metals} n: 4~10 m: 20~100 or, (X) -C _{n F 2n - (CH 2 CH 2} ) - (CH 2 CH 2 0) m - (Z) X: -H or _{-F Z: -CH 3, -P0 3} W 2 or -SO ₃ W {W is an alkali metal Those represented by the genus n: 4 to 10 m: 40 to 100 are effective.

The corrosion-resistant zinc alloy of the present invention, the inorganic inhibitor, the material of the organic inhibitor, and the combination and composition in the composite thereof have been found as a result of intensive research so that each of them can exert the composite effect to the maximum. . Although the elucidation of its mechanism of action is unclear at present,
It is inferred as follows.

First, the functions and effects of the additive elements of the alloy, the inorganic inhibitor, and the organic inhibitor alone are as follows.

Among the additional elements in the alloy, indium, lead and bismuth have a high hydrogen overpotential of these elements themselves, and have an effect of being added to zinc to increase the hydrogen overpotential on the surface. When these are uniformly added to the alloy, the effect is maintained even if a new zinc surface appears due to the discharge, because the added elements are present at every depth of the powder. Also, aluminum and calcium have the effect of spheroidizing zinc particles, and reduce the amount of corrosion per unit weight of zinc powder to reduce the true specific surface area.

The alkali metal sulfide dissolves in the alkaline electrolyte as alkali metal ions and sulfur ions. This sulfur ion reacts with zinc when coexisting with the zinc alloy to form an inert zinc sulfide film on the surface of the zinc alloy, thereby suppressing a corrosion reaction on the surface.

When a surfactant coexists with a zinc alloy in a gelled alkaline electrolyte, the surfactant chemically adsorbs on the zinc alloy surface based on the principle of metallic soap to form a hydrophobic monomolecular weight and exhibits an anticorrosion effect. In particular, surfactants having polyethynylene oxide in the hydrophilic part have high solubility as micelles in the alkaline electrolyte, and when introduced into the electrolyte, transfer to the zinc alloy surface,
The anticorrosion effect is high because adsorption occurs quickly. Furthermore, if the fluorinated alkyl group is held on the lipophilic portion, it is effectively isolated from the electron transfer of the corrosion reaction because of its high electrical insulation when it is adsorbed on the surface of the zinc alloy. continue.

Next, the meaning of limiting the molecular structure of the surfactant will be described. Surfactant having polyethylene oxide in the hydrophilic part has high solubility as a micelle in the alkaline electrolyte, and when injected into the electrolyte, migration and adsorption to the zinc alloy surface occur quickly, resulting in high anticorrosion effect . Also,
If the terminal of the polyethynylene oxide is a hydroxyl group, that is, an alcohol, the terminal is liable to be hydrolyzed in an alkaline electrolyte. Therefore, the terminal group is preferably a methyl group, a sulfone group, or a phosphate group having strong alkali resistance. When a fluorinated alkyl group is held in the lipophilic portion, when it is adsorbed on the surface of the zinc alloy, it has a high electrical insulation property and effectively eliminates the electron transfer of the corrosion reaction. If the bonding group between the hydrophilic part and the lipophilic part is a water-repellent alkyl group, if it is a hydrophilic amide group or a sulfoamide group, chemical adsorption with zinc occurs at this part, and the corrosion resistance is high.

Next, a composite effect of a zinc alloy and a sulfide of an alkali metal will be described. Since the sulfide of the alkali metal forms an inert zinc sulfide film on the surface of the zinc alloy and acts, the reaction needs to occur smoothly and uniformly. Since significant hydrogen gas is generated on the surface of the zinc alloy having no corrosion resistance, the formation of the zinc sulfide film is alienated, and the state of the film becomes uneven. However, the generation of hydrogen gas is suppressed on the surface of a zinc alloy having good corrosion resistance, and the formation of a film occurs smoothly and uniformly, so that a combined effect can be obtained.
Further, a component effective for a corrosion resistance effect in the zinc alloy is concentrated on the surface by an electrochemical reaction between zinc and sulfur ions. Especially,
It is effective for corrosion resistance after partial discharge.

Next, the combined effect of a corrosion-resistant zinc alloy, a sulfide of an alkali metal and a surfactant will be described. The mechanism of action of the sulfide of the alkali metal is as described above. However, if all of the metal sulfides react, there will be no substance that acts after the partial discharge. It is considered that the surfactant, in addition to its own action, suppresses an electrochemical reaction between sulfur ions and zinc more than necessary, and acts to secure an amount of action after partial discharge.

Examples Hereinafter, details and effects of the present invention will be described with reference to examples.

First, the structure of the LR6 type alkaline manganese battery used in the examples and the method of comparative evaluation of liquid leakage resistance will be described in order to show the effect of the manufacturing method of the present invention in the method of producing a corrosion resistant zinc alloy.

The corrosion-resistant zinc alloy powder is prepared by melting zinc with a purity of 99.97%, adding a predetermined amount of a predetermined additive element, and uniformly dissolving it.
The powder was prepared by a so-called atomizing method in which powder was formed by spraying with compressed air, and this was classified with a sieve to adjust the particle size to a range of 45 to 150 mesh.

The gelled negative electrode was prepared as follows. First, a predetermined amount of an alkali metal oxide is dissolved in a 40% by weight potassium hydroxide solution (containing 3% by weight of ZnO). Next, 3% by weight of sodium polyacrylate and 1% by weight of carboxymethyl cellulose are added and gelled. Next, zinc alloy powder was added in a weight ratio twice that of the gel electrolyte and mixed.
In addition, when adding an organic inhibitor, a step of adding a predetermined amount to the gel electrolyte and aging for 2 to 3 hours before the addition of the zinc powder in the above-described adjustment step was added.

FIG. 1 shows the alkaline manganese battery LR6 used in this embodiment.
FIG. In FIG. 1, 1 is a positive electrode mixture,
2 is a gelled negative electrode characterized by the present invention, 3 is a separator, and 4 is a current collector of the gelled negative electrode. 5 is a positive electrode terminal cap, 6 is a metal case, 7 is a battery outer can, 8 is a case 6
A resin sealing body made of polyethylene for closing the opening of No. 9 is a bottom plate forming a negative electrode terminal.

The method of comparative evaluation of the leak resistance is as follows: 100 alkaline manganese batteries as shown in Fig. 1 were prototyped at a time, and partial discharge was performed to a depth of 20% of the theoretical capacity at a constant current of 1A, which is the most severe condition for LR6 The number of batteries that leaked after storage at 60 ° C. was evaluated as a leak index (%). The leak resistance under these severe conditions is practical if the leak index is 0% after storage at 60 ° C for 30 days, but the performance related to reliability such as leak resistance can be maintained for as long as possible. desirable.

Example 1 The present invention in the case where a zinc alloy and an inorganic inhibitor are combined will be described.

First, various additional elements of the zinc alloy were examined in advance by changing the composition in various ways. As a result, a zinc alloy containing indium as an essential alloy component, and further containing lead and bismuth alone or in combination,
Alternatively, it has been found that a zinc alloy system containing indium as an essential component, lead and bismuth alone or in combination with each other, and calcium and aluminum alone or in combination with each other is satisfactory. Table 1 shows the best alloy composition group among them.

Table 2 shows the results of the liquid leakage test of the batteries prepared by changing the amount of potassium sulfide (K ₂ S) added to the various zinc alloys shown in Table 1 after storage at 60 ° C. for 30 days.

As shown in Table 2, even a zinc alloy having excellent corrosion resistance cannot secure a very practical liquid leakage resistance by itself. However, it is understood that leakage resistance can be ensured by adding an appropriate amount of sulfide of the alkali metal. The amount of the alkali metal sulfide added to each zinc alloy is preferably in the range of 0.005 to 0.5 wt%.

Table 3 shows that the amount of potassium sulfide (K ₂ S) was fixed at 0.1 wt%, and the amount of alloying elements was changed.
The results of the liquid leakage test after storage at 60 ° C for 30 days are shown.

From Table 3, the amount of indium added to the zinc alloy is from 0.01 to
It can be seen that 1 wt%, lead and bismuth are each used alone or 0.005 to 0.5 wt% in total, and calcium and aluminum are used alone or in total 0.005 to 0.2 wt%.

Example 2 Table 4 shows that the amount of sulfide added to each of the various zinc alloys shown in Table 1 was fixed to an optimum amount of 0.1 wt%, and the type was potassium polysulfide.
The results of a liquid leakage test after storage at 60 ° C. for 30 days for batteries prepared by changing to sodium sulfide, sodium polysulfide, and lithium sulfide are shown.

Table 4 shows that the same effects as potassium sulfide (K ₂ S) can be obtained with polypotassium sulfide, sodium sulfide, and lithium sulfide. The effect can also be obtained with sodium polysulfide, lithium polysulfide, and rubidium sulfide.

The sulfide used here is obtained by dry-reacting and synthesizing an alkali metal and sulfur. As another synthesis method, in the case of potassium sulfide and sodium sulfide, there is a wet method of synthesizing with an aqueous solution of a hydroxide and hydrogen sulfide.

Table 5 shows the results of a liquid leakage test after storage at 60 ° C. for 45 days of a battery obtained by adding the optimum 0.1 wt% of potassium sulfide using different methods of synthesis to the various zinc alloys shown in Table 1 above.

Thus, it can be seen that the effect obtained by the wet method is greater than that obtained by the dry method.

Example 3 An example in which a zinc alloy and an inorganic inhibitor and an organic inhibitor are added in combination will be described.

Table 6 shows the results of the liquid leakage test after storage at 60 ° C for 60 days for batteries prepared by fixing the amount of potassium sulfide to the optimum amount of 0.1 wt% and changing the amount of the organic inhibitor to each zinc alloy. .

From this, it is understood that the appropriate amount of the organic inhibitor is 0.001 to 0.1 wt% for each zinc alloy.

Even when an organic inhibitor is added, the amount of indium added to the zinc alloy is 0.01 to 1% by weight, and lead and bismuth are used alone or in a total of 0.005%, as in the case of adding a zinc alloy and an inorganic inhibitor in combination. ~ 0.5
It was suitable that each of wt%, calcium and aluminum was used alone or in a total amount of 0.005 to 0.2 wt%. Also,
The type and concentration range of the inorganic inhibitor were the same as in the case where the zinc alloy and the inorganic inhibitor were added in combination.

Surfactant used in Example 3 the following structural formula _{(X) -C n F 2n -} (Y) - (CH 2 CH 2 0) m - (Z) X: -H, Y: -CONH-, Z: —CH ₃ n: 9 and m: 40 were used.

Following structural formula _{(X) -C n F 2n -} (Y) - (CH 2 CH 2 0) m - (Z) X: -H or -F Y: -CONH- or -SO ₂ NR- {R is Alkyl group｝ Z: —CH ₃ , P ₃ W ₂ or —SO ₃ W ｛W is an alkali metal｝ n: 4 to 10 m: 20 to 100 or (X) —C _n F _2n — (CH ₂ CH _{2 ) - (CH 2 CH 2 0} ) m - (Z) X: -H or _{-F Z: -CH 3, -P0 3} W 2 or -SO ₃ W {W is an alkali metal} n: 4~10 m: If the surfactant is 40 to 100, the same or more effect can be obtained.

By the way, in all the embodiments, the effect of the present invention has been explained by using a non-melted zinc alloy. However, the effect is sufficient even when the amount of added mercury is extremely low, such as several ppm to several tens of PPM.

Effects of the Invention As described above, according to the present invention, in a zinc alkaline battery, a zinc alloy having an appropriate composition in a gel alkaline electrolyte and an alkali synthesized to have appropriate properties by an appropriate synthesis method. By adding a metal sulfide, an increase in the internal pressure of the battery due to gas generation due to the corrosion of zinc can be suppressed even with mercury-free silver, and the liquid leakage resistance of the battery can be improved. And by adding an organic inhibitor to this, it is possible to provide a pollution-free zinc-alkali battery having even better storability.

[Brief description of the drawings]

FIG. 1 is a sectional view of an alkaline manganese battery according to an embodiment of the present invention. 1 ... positive electrode mixture, 2 ... gelled negative electrode, 3 ... separator

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01M 4/06 H01M 4/06 U 4/26 4/26 H 4/42 4/42 (72) Inventor Sachiko Sugihara Okadoma, Kadoma, Osaka 1006 Matsushita Electric Industrial Co., Ltd. (56) References JP-A-2-79367 (JP, A)

Claims (8)

(57) [Claims] In the preparation of a gelled negative electrode in which zinc alloy powder is mixed and dispersed in a gelled alkaline electrolyte, indium,
Using a zinc alloy containing at least one of a group of lead, bismuth, calcium and aluminum as an active material,
A method for producing a zinc alkaline battery, characterized in that the alkaline electrolyte contains 0.05 to 0.5% by weight of an alkali metal sulfide based on the zinc alloy. 2. A negative electrode active material comprising a zinc alloy containing 0.01 to 1% by weight of indium and one or two types of lead and bismuth in total of 0.005 to 0.5% by weight. The method for producing a zinc alkaline battery according to the above item. 3. An indium content of 0.01 to 1 wt%, a total of 0.005 to 0.5 wt% of one or two of lead and bismuth, and a total of 0.005 to 0.5 wt% of one or two of calcium and aluminum.
The method for producing a zinc alkaline battery according to claim 1, wherein a zinc alloy containing 5 to 0.2 wt% is used as a negative electrode active material. 4. A method for preparing a gelled negative electrode in which a zinc alloy powder is mixed and dispersed in a gelled alkaline electrolyte, wherein indium,
Using a zinc alloy containing at least one of a group of lead, bismuth, calcium and aluminum as an active material,
In the alkaline electrolyte, a sulfide of an alkali metal is contained in an amount of 0.0005 to 0.5 wt% based on the zinc alloy, and a surfactant having polyethylene oxide in a hydrophilic part is contained in an amount of 0.001 to 0.1 wt% based on the zinc alloy. A method for producing a zinc-alkaline battery, comprising: 5. A negative electrode active material comprising a zinc alloy containing 0.01 to 1% by weight of indium and 0.005 to 0.5% by weight of a total of one or two of lead and bismuth. The method for producing a zinc alkaline battery according to the above item. 6. An indium of 0.01 to 1 wt%, a total of 0.005 to 0.5 wt% of one or two of lead and bismuth, and a total of 0.005 to 0.5 wt% of calcium and aluminum.
5. The method for producing a zinc alkaline battery according to claim 4, wherein a zinc alloy containing 5 to 0.2% by weight is used as a negative electrode active material. 7. A surfactant having a polyethylene oxide hydrophilic portion structural formula _{(X) -C n F 2n -} (Y) - (CH 2 CH 2 0) m - (Z) X: -H or -F Y: -CONH- or -SO ₂ NR- {R represents an alkyl _{group} Z: -CH 3, -P0 3} W 2 or -SO ₃ W {W is an alkali metal} n: 4~10 m: 20~ The method for producing a zinc alkaline battery according to claim 4, wherein the method is represented by 100. 8. surfactant having a polyethylene oxide hydrophilic portion structural formula _{(X) -C n F 2n -} (CH 2 CH 2) - (CH 2 CH 2 0) m - (Z) X: -H or _{-F Y: -CH 3, -P0 3} W 2 or -SO ₃ W {W is an alkali metal} n: 4~10 m: the claims represented by 40 to 100 range described paragraph 4 Manufacturing method of zinc alkaline battery.