JPH0426067A - Manufacture of zinc-alkali battery - Google Patents

Abstract

PURPOSE:To improve resistance to electrolyte leakage by adding specified amounts of a zinc alloy with a proper composition as well as a specified alkali metal sulfide and an indium compound. CONSTITUTION:A gel negative pole 2 is composed of an active mass of a corrosion-resistant zinc alloy powder prepared by adding proper amounts of indium, lead, bismuth, calcium, and/or aluminum with a proper combination to zinc and a gel alkaline electrolyte in which an alkali metal sulfide as well as indium oxide, indium hydroxide, or indium sulfide are dissolved as inorganic inhibitors each in 0.002-0.2 wt.% of the zinc alloy. Consequently, corrosion reaction accompanied by gas production is suppressed and the pressure increase in a battery is prevented, so that resistance to electrolyte leakage is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention uses zinc as a negative electrode active material, an alkaline aqueous solution as an electrolyte, and manganese dioxide, silver oxide, or silver oxide as a positive electrode active material.
The present invention relates to mercury-free technology for zinc-alkaline batteries using oxygen, etc., and provides a method for manufacturing zinc-alkaline batteries that is pollution-free and has excellent storage and discharge performance.

Conventional Technology Approximately ten years ago, there was a strong concern about environmental pollution caused by mercury in waste batteries, and research was conducted into reducing the amount of mercury in alkaline batteries. As a result, with the development of corrosion-resistant zinc alloys, etc., the amount of mercury contained in alkaline dry batteries is currently being reduced to 250 ppm relative to the battery weight. However, now that there is worldwide concern about environmental destruction caused by industrial products, as exemplified by the problem of ozone layer depletion caused by fluorocarbons, there is an increasing demand for the complete elimination of mercury in alkaline batteries.

The approach to mercury-free alkaline batteries is as follows:
This has been done since the time when mercury-containing alkaline batteries were being developed, and numerous patents and Japanese publications have been filed and published regarding various materials related to zinc alloys, inorganic inhibitors, and organic inhibitors.

Indium is a material with a high hydrogen overvoltage and is known as an additive to the negative electrode of secondary batteries, regardless of the type of battery. Many applications and publications have also been made regarding methods of using metallic indium as an alloy additive element and methods of using indium compounds as inorganic inhibitors.

For example, the method of using it as an alloy additive element (Japanese Patent Publication No. 1-
41576), a method using indium oxide and indium hydroxide as inorganic inhibitors (Japanese Patent Publication No. 1973-
36450, JP 4993831, JP 49-11
2125, 56th Electrification Conference Abstracts Presentation Number 3G
O5; page 205), method of adding indium oxide and cadmium oxide in combination (JP-A-1-105466)
and so on. In addition, examples of adding it as an additive to the negative electrode of a secondary battery (JP-A-61-96666, JP-A-6L-10
1955) is also available.

In addition, organic inhibitors include jetanolamine,
Oleic acid, lauryl ether or ethylene oxide polymers have been proposed.

Further, as an example of the combined addition of an inorganic inhibitor and an organic inhibitor, the combined addition of indium hydroxide and an ethoxylfluoroalcohol-based polyfluoride compound has been proposed (Japanese Patent Laid-Open No. 279367).

Problems to be Solved by the Invention In batteries that use pure zinc without mercury as the active material of the negative electrode,
The corrosion reaction of zinc accompanied by hydrogen generation occurs violently, increasing the internal pressure of the battery and pushing the electrolyte to the outside, resulting in a problem of reduced leakage resistance.

Additionally, in a partially discharged battery, the rate of hydrogen generation in the zinc negative electrode is accelerated, further reducing leakage resistance.

These results are due to the disappearance of mercury, which was suppressing corrosion reactions, by increasing the hydrogen overvoltage on the zinc surface.

Even with a corrosion-resistant zinc alloy containing indium, aluminum, and lead, which has been proven to have a corrosion-resistant effect by reducing mercury in the zinc negative electrode, if a battery is constructed without mercury, the leakage resistance of the battery after partial discharge cannot be ensured.

In addition, a battery constructed by adding commercially available indium oxide or indium hydroxide to a gel negative electrode using pure zinc powder as the negative electrode active material is as practical as a battery constructed only of the above-mentioned corrosion-resistant alloy. Leak resistance cannot be ensured.

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

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

In order to make alkaline dry batteries mercury-free, the present inventors have developed materials that can exhibit the best combined effects of corrosion-resistant zinc alloys, inorganic inhibitors, and organic inhibitors, as well as their optimal conditions. The concentration was studied.

Means for Solving the Problems First, the present invention will be described in detail regarding the combined use of a corrosion-resistant zinc alloy and an inorganic inhibitor. The gelled negative electrode in the present invention includes indium, lead, bismuth, calcium,
Corrosion-resistant zinc alloy powder, which is made by adding an appropriate amount of any one of the groups of aluminum and aluminum to zinc, is dissolved as an active material and an appropriate amount of alkali metal sulfide as an inorganic inhibitor, and then indium oxide It is composed of a gel-like alkaline electrolyte in which indium hydroxide or indium sulfide is dispersed at an appropriate concentration.

The above corrosion-resistant zinc alloy contains 001 to 1wt of indium.
%, one or two types of lead and bismuth in total 0.0
Zinc alloy containing 05 to 0.5 wt%, or 0.01 to 1 wt% of indium, a total of 0.005 to 0.5 wt% of one or both of lead and bismuth, and one or two of calcium and aluminum. 0゜0 in total
05~0. It is a zinc alloy containing 2 wt%. Additionally, the amount of the alkali metal sulfide added is 0.002 to 0.2 wt% to the zinc alloy, and the amount of indium oxide, indium hydroxide, or indium sulfide added is 0.002 to 0.0% to the zinc alloy. .2wt%.

Next, the present invention will be described in detail regarding the combined use of a zinc alloy, an inorganic inhibitor, and an organic inhibitor. The gelled negative electrode of the present invention is produced by dissolving a corrosion-resistant zinc alloy powder in which indium, lead, bismuth, calcium, and aluminum are added in an appropriate combination and in an appropriate state, and an appropriate amount of alkali metal sulfide. By using a gel-like alkaline electrolyte in which indium hydroxide or indium sulfide is dispersed at an appropriate concentration, and an appropriate amount of a surfactant having polyethylene oxide in the hydrophilic part and a fluorinated alkyl group in the lipophilic part is added. configured.

The above surfactant is 0.001 to 0.0.
It is effective to contain it in a 1wt% alkaline electrolyte.

In addition, the corrosion-resistant zinc alloy contains 0.01 to 1 wt of indium.
%, one or two types of lead and bismuth in total 0.0
Zinc alloy containing 0.05 to 0.5 wt%, or 0.01 to 1 wt% of indium, a total of 0.005 to 0.5 wt% of one or both of lead and bismuth, and one or two of calcium and aluminum. 0.0 in total
It is a zinc alloy containing 05 to 02 wt%. In addition, the amount of the alkali metal sulfide added above is 0 to the zinc alloy.
．． The amount of indium oxide, indium hydroxide or indium sulfide added is 0.002 to 0.2 wt% based on the zinc alloy.

Furthermore, the surfactant has the following structural formula (X) 4-10 m・20-100 or (X)ic, F2n(CH2CH2)-(CH2C
H20) m-(Z)
10 m: 40 to 100, and the famous one is effective.

Function: The materials of the corrosion-resistant zinc alloy, inorganic inhibitor, and organic inhibitor of the present invention, as well as the combination and composition of their composites, were discovered as a result of intensive research to maximize the combined effects of each. Although the elucidation of its mechanism of action is currently unclear, it is inferred as follows.

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

Among the additive elements in the alloy, indium, lead, and bismuth have high hydrogen overvoltages themselves, and when added to zinc, they have the effect of increasing the hydrogen overvoltage on the surface. When added uniformly into the alloy, this effect is retained even if a new zinc surface appears due to the electrical discharge, since the added element is present at every depth in the powder. Furthermore, aluminum and calcium have the effect of making zinc particles spherical, reducing the true specific surface area, thereby reducing the amount of corrosion per unit weight of zinc powder.

When indium oxide, indium hydroxide, and indium sulfide are dispersed as powder in a gel-like alkaline electrolyte in coexistence with a zinc alloy, the negative part is electrodeposited as metallic indium on the surface of the zinc alloy by the principle of displacement plating. Increase the hydrogen overvoltage on its surface. The remaining part remains as a solid in the electrolyte, and when a new zinc alloy surface appears due to discharge, it is electrodeposited on this new surface and exhibits a corrosion-preventing effect. The action and effect of oxides and sulfides after discharge are higher than those of hydroxides because of their low solubility.

Alkali metal sulfides dissolve in alkaline electrolytes as alkali metal ions and sulfur ions. When these sulfur ions coexist with zinc alloy, they react with zinc, forming an inert zinc sulfide film on the surface of the zinc alloy, and suppressing corrosion reactions on the surface.

When a surfactant coexists with a zinc alloy in a gel-like alkaline electrolyte, it chemically adsorbs onto the surface of the zinc alloy based on the principle of metal soap, forming a hydrophobic monomolecular layer, which exhibits an anticorrosion effect. especially,
Surfactants with polyethylene oxide in the hydrophilic part are
It has high solubility as a micelle in an alkaline electrolyte, and when added to the electrolyte, it quickly migrates and adsorbs to the surface of the zinc alloy, resulting in a high anticorrosion effect. Furthermore, if the oleophilic moiety has a fluorinated alkyl group, when it is adsorbed on the surface of the zinc alloy, it has high electrical insulation properties, so it effectively eliminates electron transfer during corrosion reactions, and its strong alkali resistance makes it less effective. last.

Next, the meaning of limiting the molecular structure of the surfactant will be explained. Surfactants with polyethylene oxide as their hydrophilic part have high solubility as micelles in alkaline electrolytes, and when added to electrolytes, they migrate to the zinc alloy surface,
It has a high corrosion prevention effect because adsorption occurs quickly. In addition, if the terminal end of polyethylene oxide is a hydroxyl group, that is, an alcohol, it is easily hydrolyzed in an alkaline electrolyte.
Phosphoric acid groups are preferred. If a fluorinated alkyl group is present in the lipophilic moiety, when it is adsorbed on the surface of a zinc alloy, it has high electrical insulation properties and effectively eliminates the transfer of electrons in the corrosion reaction. If the bonding group between the hydrophilic part and the lipophilic part is a hydrophilic amide group or sulfoamide group rather than a water-repellent alkyl group, chemical adsorption with zinc will occur in this part, resulting in high corrosion resistance.

Next, the combined effect of indium compounds, sulfides, and zinc alloys will be explained. Since indium acts by being electrodeposited on the surface of the zinc alloy, the electrodeposition must occur smoothly and uniformly. Since a significant amount of hydrogen gas is generated on the surface of the zinc alloy, which has no corrosion resistance, the electrodeposition of indium is hindered and the state of the electrodeposition becomes non-uniform. However, on the surface of a zinc alloy with good corrosion resistance, the generation of hydrogen gas is suppressed, and electrodeposition occurs smoothly and uniformly, resulting in a composite effect. Sulfur ions react with zinc and help the above effects by etching the zinc surface and concentrating alloying elements effective for corrosion prevention. This also applies to the state after partial discharge.

Next, the case where a surfactant is further added to the above composite will be explained. The mechanism of action of the indium compound and sulfur ion is as described above, but if all of them react at the initial stage, there will be nothing left to act after the partial discharge. In addition to its own action, the surfactant is thought to play the role of suppressing the unnecessary electrodeposition of indium and the reaction of sulfur ions with zinc, and ensuring the amount that will act after reactive partial discharge.

EXAMPLES The details and effects of the present invention will be explained below using examples.

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

Corrosion-resistant zinc alloy powder is produced by melting 99.97% pure zinc, adding specified amounts of specified additive elements, and uniformly dissolving it.
It is made by the so-called a) maize method, which involves spraying with compressed air and pulverizing it, and then classifying it with a sieve to obtain particles with a particle size ranging from 45 to 1.
Adjusted to 50 mesh. The gelled negative electrode was prepared as follows.

First, a 40% by weight potassium hydroxide solution (3w of ZnO
A predetermined amount of alkali metal sulfide is dissolved in a solution (containing t%), and 3% by weight of sodium polyacrylate and 1% by weight of carboxymethylcellulose are added to form a gel. Next, a predetermined amount of indium compound powder is gradually added to the gel electrolyte while stirring, and the electrolyte is aged for 2 to 3 hours. Furthermore, twice the weight ratio of zinc alloy powder was added to the gel electrolyte and mixed. In addition, when adding an organic inhibitor, before adding indium sulfide during the above adjustment process,
A predetermined amount of this was added to a gel electrolytic solution and a step of aging for 2 to 3 hours was added.

Figure 1 shows the alkaline manganese battery LR6 used in this example.
FIG. In FIG. 1, 1 is a positive electrode mixture;
2 is a gel negative electrode characterized by the present invention, 3 is a separator, and 4 is a current collector of the gel negative electrode. 5 is the positive terminal cap, 6 is the metal case, 7 is the battery exterior can, 8 is the case 6
A resin sealing body made of polyethylene closes the opening, and 9 is a bottom plate forming a negative electrode terminal.

The method for comparative evaluation of leakage resistance was to prototype 100 alkaline manganese batteries each as shown in Fig.

Partial discharge was performed to a depth of 20% of the theoretical capacity at a constant current of IA, which is the most severe condition for R6, and the number of batteries leaking after storage at 60° C. was evaluated as a leakage index (%). Under these harsh conditions, the leakage index is 0% after 30 days of storage at 60°C.
However, it is desirable that reliability-related performance such as leakage resistance can be maintained for as long as possible.

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

First, various additive elements were investigated in advance by changing the composition of the zinc alloy. As a result, a zinc alloy containing indium as an essential alloy component, and lead and bismuth, either singly or in combination, or indium as an essential component, lead and bismuth, either alone or in combination, and calcium. It was found that a zinc alloy system containing aluminum alone or in combination is good when used alone. Table 1 shows the best alloy composition group among them.

Table 1 Corrosion-resistant zinc alloy for mercury-free alkaline zinc batteries (in the table)
) indicates the amount of alloy components added> Table 2 shows the results of batteries created by fixing the amount of indium hydroxide added to 0.1 wt% and varying the amount of potassium sulfide added to the various zinc alloys shown in Table 1 above. The results of a leakage test after storage at 60°C for 60 days are shown.

Table 3 shows the leakage after storage at 60°C for 60 days of batteries prepared by fixing the amount of potassium sulfide added to O, 1wt% and varying the amount of indium hydroxide added to the various zinc alloys shown in Table 1 above. Shows the liquid test results.

From Tables 2 and 3, it can be seen that even zinc alloys with excellent corrosion resistance cannot ensure practical leakage resistance by themselves. However, appropriate amounts of potassium sulfide and indium hydroxide,
It can be seen that by adding this, leakage resistance can be ensured. The amount of indium hydroxide added to each zinc alloy is 0.
A range of 0.002 to 0.02 Wt% is good. The amount of potassium sulfide added is preferably in the range of 0.002 to 0.2 wt%.

Table 4 shows the leakage test results after storage at 60° C. for 60 days for batteries prepared by fixing the amounts of potassium sulfide and indium hydroxide at 0.1 wt% each and varying the amounts of alloy component elements.

From Table 4, the amount of indium added to the zinc alloy is 0.01
~l wt%, lead and bismuth, each singly or in total, 0.005 to 0.5 wt%, calcium and aluminum, each singly or in total, 0.005 to 0.5 wt%.
It can be seen that 0.005 to 0.2 wt% is appropriate.

Example 2 An example will be described in which a zinc alloy, an inorganic inhibitor, and an organic inhibitor are added in combination.

Table 5 shows the batteries prepared at 60℃7 for each zinc alloy by fixing the amounts of potassium sulfide and indium hydroxide at 0.1 wt% each and varying the amount of organic inhibitor added.
The results of the leakage test after 5 days of storage are shown.

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

Even when an organic inhibitor is added, as in the case where a zinc alloy and an inorganic inhibitor are added in combination, the amount of indium added to the zinc alloy is 0.001 to 1 wt%, and the amount of lead and bismuth, either alone or in total, is LOO5.
Appropriate amounts were ~0.5 wt%, and 0.005 to 0.2 wt% for calcium and aluminum, each alone or in total.

The surfactants used in Table 3 have the following chemical structural formula: (X) :60 I used something that is.

The following structural formula (X)
4~Co Om・20~100 or (X)-Cn F2II (C)12 CH2)
-(CH2CH20)m -(Z)X -H or -
A similar or better effect can be obtained if the surfactant is FZ-CH3-PO3W2 or -3O3W (W is an alkali metal) 14-10 m:40-100. Note that among the above-mentioned surfactants, the phosphoric acid type surfactants may be a mixture of primary and secondary phosphates.

The alkali metal sulfide used in the examples was potassium sulfide (
K2S), but similar effects can be obtained with potassium polysulfide, sodium sulfide, lithium sulfide, sodium polysulfide, lithium polysulfide, and rubidium sulfide.

In the examples, indium hydroxide using sulfate as a starting material was used, but effects can also be obtained using chlorides or nitrates as starting materials. The degree of effectiveness was higher in the following order: those using chloride as a starting material, those using sulfate as a starting material, and those using nitrate as a starting material.

Indium hydroxide can also be replaced with indium sulfide and indium oxide. Its particle size is 0
．． Powder containing 80 wt % or more of particles in the range of 5 to 8 μm can provide sufficient or better leakage resistance.

Incidentally, in all the examples, the effects of the present invention have been explained using a non-viscous zinc alloy, but the effects are sufficient even when the mercury content is extremely low, ranging from 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-like alkaline electrolyte, an appropriate alkali metal nosulfide, and an appropriate synthesis method can be used. By adding an appropriate amount of an indium compound synthesized to have specific physical properties, it is possible to suppress the increase in battery internal pressure due to corrosion of zinc even in the absence of mercury, thereby improving the leakage resistance of the battery. By adding an organic inhibitor to this, a pollution-free zinc-alkaline battery with even better storage stability can be provided.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an alkaline manganese battery in an embodiment of the present invention.

Claims (8)

[Claims] (1) In preparing a gel-like negative electrode in which zinc alloy powder is mixed and dispersed in a gel-like alkaline electrolyte, a zinc alloy containing at least one member from the group of indium, lead, bismuth, calcium, and aluminum is used as an active material, The alkaline electrolyte contains an alkali metal sulfide of 0.002 to 0.2 wt% based on the zinc alloy, and further contains 0.002 to 0.2 wt% of an alkali metal sulfide based on the zinc alloy, and further contains 0.002 to 0.2 wt% of an alkali metal sulfide based on the zinc alloy. .002~0.2
A method for manufacturing a zinc-alkaline battery, characterized in that the zinc-alkaline battery contains wt%. (2) 0.01 to 1 wt% of indium and 0.005 to 0.5 wt of one or both of lead and bismuth in total
% of zinc alloy is used as a negative electrode active material. (3) 0.01 to 1 wt% of indium and 0.005 to 0.5 wt of one or both of lead and bismuth in total
Claim 1, characterized in that a zinc alloy containing a total of 0.005 to 0.2 wt% of one or both of calcium and aluminum is used as the negative electrode active material.
A method for producing a zinc-alkaline battery as described in Section 1. (4) In preparing a gel-like negative electrode in which zinc alloy powder is mixed and dispersed in a gel-like alkaline electrolyte, a zinc alloy containing at least one member from the group of indium, lead, bismuth, calcium, and aluminum is used as an active material, In the alkaline electrolyte, 0.0002 to 0.2 wt% of alkali metal sulfide is contained relative to the zinc alloy, and 0.002 wt% of any of indium oxide, indium hydroxide, or indium sulfide is contained relative to the zinc alloy. ~0.2wt% of each, and a surfactant having polyethylene oxide in the hydrophilic part at a concentration of ~0.001% by weight relative to the zinc alloy.
A method for manufacturing a zinc-alkaline battery characterized by containing 0.1 wt%. (5) 0.01 to 1 wt% of indium and 0.005 to 0.5 wt of one or both of lead and bismuth in total
5. The method for manufacturing a zinc-alkaline battery according to claim 4, characterized in that a zinc alloy containing % of zinc is used as a negative electrode active material. (6) 0.01 to 1 wt% of indium and 0.005 to 0.5 wt of one or both of lead and bismuth in total
Claim 4, characterized in that a zinc alloy containing a total of 0.005 to 0.2 wt% of one or both of calcium and aluminum is used as the negative electrode active material.
A method for producing a zinc-alkaline battery as described in Section 1. (7) A surfactant having polyethylene oxide in its hydrophilic part has the following structural formula (X)-C_nF_2_n-(Y)-(CH_2CH_
2O)_m-(Z)
0 m: 20 to 100. The method for producing a zinc-alkaline battery according to claim 4. (8) A surfactant having polyethylene oxide in its hydrophilic part has the following structural formula (X)-C_nF_2_n-(CH_2CH_2)-(
CH_2CH_2O)_m-(Z)X:-H or-
F Z: -CH_3, -PO_3W_2 or -SO_3W {W is an alkali metal} n: 4 to 1
0 m: 40-100 The method for manufacturing a zinc-alkaline battery according to claim 4.