JPH0426064A - Manufacture of zinc-alkali battery - Google Patents

Abstract

PURPOSE:To improve resistance to electrolyte leakage by adding specified amounts of a zinc alloy having a proper composition and indium hydroxide having specified crystal structure to a gel alkaline electrolyte. 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 containing indium hydroxide with a crystal structure having peaks at 4.71+ or -0.10Angstrom , 3.98+ or -0.02Angstrom , 3.57+ or -0.10Angstrom , and 2.66+ or -0.02Angstrom in an X-ray diffractometry as an inorganic inhibitor. The crystal of the indium hydroxide is effective to corrosion. As a result, resistance to electrolyte leakage is improved.

Description

[Detailed Description of the Invention] The gelled negative electrode in the invention consists of a corrosion-resistant zinc alloy powder in which a suitable combination and appropriate amount of any one of the group consisting of indium, lead, bismuth, calcium, and aluminum is added to zinc. The active material and the inorganic inhibitor have an X-ray diffraction pattern of 4.71±0.10Å and 3.98±
0.02 Å, 3.57 ± 0.10 Å, 2.66 ± 0.0
It is composed of a gel-like alkaline electrolyte in which indium hydroxide, which has a crystal structure that exhibits two peaks, is dispersed at an appropriate concentration.

The above corrosion-resistant zinc alloy contains 0.01 to 1 w of indium.
t%, one or both of lead and bismuth in total of 0.
Zinc alloy containing 0.005 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 a type of calcium and a/l/miniram. Or two types in total 0.005 to 0. It is a zinc alloy containing 2 wt%. Further, the amount of indium hydroxide added is 0.005 to 0.5 wt% based on the zinc alloy.

Next, the present invention will be described in detail regarding a zinc alloy, a composite of an inorganic inhibitor and an organic inhibitor. The gelled negative electrode of the present invention has a corrosion-resistant zinc alloy powder added with a proper combination of indium, lead, bismuth, calcium, and aluminum in a proper amount, and an inorganic inhibitor that has an X-ray diffraction pattern of 471±0. .10Å, 3.98±0.02Å, 357±
Indium hydroxide having a crystal structure showing a peak at 0.10 Å and 2.66 ± 0.02 is dispersed at an appropriate concentration, and further has polyethylene oxide in the hydrophilic part and a fluorinated alkyl group in the lipophilic part. and a gel-like alkaline electrolyte to which an appropriate amount of surfactant is added.

The above surfactant is 0.001 to 0.0.
It is effective to include it in the alkaline electrolyte at 1 wt%.

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 two of lead and bismuth, and a total of one or two of calcium and aluminum. at 0.0
It is a zinc alloy containing 0.05 to 0.2 wt%. The preferred amount of indium hydroxide added here is 0.005 to 0.5 wt% based on the zinc alloy.

In addition, the surfactant has the following structural formula (X). 4-1
0 m: 20-100 or (X)-CnF20(CH2CH2)-(C)
12 CH20)m -(Z)X・-■] or -
F Z Ni CH3, -PO: ] W2 or -S03 W fW is an alkali metal) n 4
~10 m: 40 to 100 m 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 overpotentials themselves, and when added to zinc, they have the effect of increasing the hydrogen overvoltage on the surface. When these are uniformly added to the alloy, the above effect is maintained even if a new zinc surface appears due to discharge, since the added element is present at any 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 hydroxide is dispersed as a powder in a gel-like alkaline electrolyte in coexistence with a zinc alloy, a portion of it is deposited as metallic indium on the surface of the zinc alloy using the principle of displacement plating, and the hydrogen overvoltage on the surface is reduced. enhance 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 the new surface and exhibits a corrosion-preventing effect.

Next, the meaning of limiting the properties of indium hydroxide will be explained. Its crystallinity is directly related to its solubility in an alkaline electrolyte; the worse the crystallinity, the better the solubility. Crystallinity is also related to the particle size of the powder, and the worse the crystallinity, the finer the particle size.

The finer the particle size, the better the dispersibility in the gel electrolyte.
The gel negative electrode can exhibit uniform effects. The indium hydroxide crystal of the present invention is a crystal that is effective in preventing corrosion.

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 onto the surface of the zinc alloy, it has high electrical insulation properties, effectively eliminating electron transfer during corrosion reactions, and has strong alkali resistance, so its effect is negligible. 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 group is good. 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 higher corrosion resistance.

Next, the combined effect of indium hydroxide and zinc alloy will be explained. Since indium acts by being electrodeposited on the surface of the zinc alloy, the electrodeposition must occur smoothly and uniformly. Significant hydrogen gas is generated on the surface of the zinc alloy, which has no corrosion resistance, which prevents indium electrodeposition.
The state of 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.

Next, a case where a surfactant is further added to the above composite will be explained. The mechanism of action of indium hydroxide is as described above, and if all of it reacts at the initial stage, there will be nothing left to act on after the partial discharge. In addition to its own function, the surfactant is thought to have the function of suppressing the electrodeposition of more indium than necessary and ensuring the amount of indium that is available after partial discharge.

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

First, in order to demonstrate the effects of the method of creating a corrosion-resistant zinc alloy, the method of synthesizing indium hydroxide, and the manufacturing method of the present invention, we will discuss the structure of the LRe-type alkaline manganese battery used in the examples and the method of comparative evaluation of leakage resistance. explain.

Corrosion-resistant zinc alloy powder is created by the so-called atomization method, in which zinc with a purity of 9997% is melted, a predetermined amount of predetermined additive elements are added, the mixture is uniformly dissolved, and then the powder is sprayed with compressed air to form a powder. It was classified and adjusted to a particle size range of 45 to 150 mesh.

Indium hydroxide was neutralized by adding a saturated amount of a specified indium salt to ion-exchanged water, and stirring the aqueous solution with a screw stirrer until the pH of the aqueous solution reached 9 using ammonia gas as a neutralizing agent. After that, the pH of the oral performance was adjusted to 7 with ion-exchanged water on a filter with a 0.5 μm coarseness.
．． It was synthesized by washing with water until the temperature reached 5.5, separating water by pulling a vacuum from under the filter, and vacuum drying at 60°C.

Indium hydroxide in the comparative example was neutralized and synthesized using indium nitrate as a starting material by the above method at a considerably slow rate. It is an X-ray diffraction diagram: 3.99±0.05Å, 2.82±0.05Å, 2.5
2±0.05A, 2.30±005 people 2.13±0.0
Shows a peak at 5 Å, 1.99±0.05. Hereinafter, this will be referred to as α type.

The first indium hydroxide is synthesized by using indium chloride as a starting material and controlling neutralization using the method described above.
Line diffraction diagram: 471±0.10Å, 3.98±002Å, 3.57±
010 Å, showing a peak at 2.66±0.02 people. Hereinafter, this will be referred to as β type.

Indium hydroxide used in the second example was synthesized using indium sulfate as a starting material in the same manner as above. This is X
Line diffraction diagram: 4.71±0.10Å, 3.98±0.02Å, 3.5
7±0.10Å, 2', 66±0.02 people 3.03±0
A peak is shown at 10 Å, 2.49±0.10.

Hereinafter, this will be referred to as the β type.

For comparison, a sample without indium hydroxide (inhibitor) was also prepared.

The gelled negative electrode was prepared as follows. First, 3% by weight of sodium polyacrylate and 1% by weight of carboxymethyl cellulose are added to a 40% by weight potassium hydroxide solution (containing 3% by weight of ZnO) to form a gel. Next, a predetermined amount of surfactant is added to the gel electrolyte while stirring, and the mixture is stirred and aged for 2 to 3 hours. Next, a predetermined amount of indium hydroxide powder is gradually added and aged for 2 to 3 hours.

Furthermore, twice the weight ratio of zinc alloy powder was added to the gel electrolyte and mixed.

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 as shown in Figure 1 and partially discharge them to a depth of 20% of the theoretical capacity at a constant current of IA, which is the most severe condition for LR6. The number of batteries that leaked after storage at 60°C was evaluated as a leakage index (%). Under these harsh conditions, if the leakage index is 0% after 30 days of storage at 60°C, it is practical, but it is desirable to be able to maintain reliability-related performance such as leakage resistance for as long as possible.

Example 1 The present invention will be described in which a zinc alloy and an inorganic inhibitor are added in combination.

First, we investigated zinc alloys by adding various additive elements and varying the composition. As a result, zinc alloys containing indium as an essential alloy component and lead and bismuth, either singly or in combination, or zinc alloys containing indium as an essential alloy, lead and bismuth, either singly 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 leakage test results after storage at 60°C for 45 days for batteries made by fixing the addition amount of three types of indium hydroxide with different crystal states to 0.1 wt% for various zinc alloys with good corrosion resistance. show.

As shown in Table 1, even zinc alloys with excellent corrosion resistance cannot ensure practical leakage resistance by themselves. However, it can be seen that by adding a certain amount of indium hydroxide in the form of β-type or β“-type crystals, leakage resistance can be ensured even at 60°C for 45 days. It seems that they are basically the same crystal system. However, those with a disordered crystal state have a much higher anti-corrosion effect and may not leak even after 60 days at 60°C. Depending on the synthesis conditions, it may be a type, β type
If indium hydroxide containing a mixture of types is produced, or if the β-type bisity is quantitatively high, a sufficient effect will be achieved.

Table 2 shows the leakage test results after storage at 60° C. for 45 days for batteries made by varying the amount of β-type crystal indium hydroxide added to various zinc alloys with good corrosion resistance.

Table 2 shows that leakage resistance can be ensured by adding an appropriate amount of indium hydroxide in a crystalline state. The amount of indium hydroxide added to various zinc alloys is 0.
．． A good range is 0.005 to 0.5 wt%.

Table 3 shows the leakage test results after storage at 60° C. for 45 days for batteries prepared by fixing the amount of indium hydroxide added at 0.1 wt% and varying the amount of alloy component elements added.

From Table 3, the amount of indium added to the zinc alloy is 0.01
~1wt%, lead and bismuth each individually or in total 0005~05wt%, calcium and aluminum each individually or in total 0.005~05wt%
It can be seen that 0.2 wt% is appropriate.

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

Table 4 shows 60% of batteries created by fixing the amount of indium hydroxide added to the optimal 0.1 wt% and varying the amount of surfactant, which is an organic inhibitor, for each zinc alloy.
The results of a leakage test after storage at ℃ for 60 days are shown.

From this, the amount of surfactant added is 0.0 for each zinc alloy.
It can be seen that 0.01 to 0.1 wt% is appropriate. In addition,
The leakage index of the battery using the formulation of the present invention in Table 4 is 60°C
All values were 0% until the 45th day.

Even when an organic inhibitor is added, the composition of the zinc alloy is indium, 0.01 to 1 wt%, and lead and bismuth, either alone or in combination, in the same way as when a zinc alloy and an inorganic inhibitor are added in combination. at 0.0
05-0.5wt%, calcium and aluminum each individually or in total 0.005-0.2wt%
% was appropriate.

The surfactant used in Example 2 has the following structural formula (X) : :60 I used something that is.

The following structural formula (X) -H or -F -CONH- or -so:qNR (R is an alkyl group) -CH3, -PO3W2 or -5O3W (W is an alkali metal) 4-10 20-100 or (X )-C2F2n ((,H2CH2)-(C
Ill 2 CH20) Ill -(Z)X: -H
Or -FZ・-CF(3,-pQ+ W2 or -5O3W (W is an alkali metal) n 4~
A surfactant having a ratio of 10 m:40 to 100 can provide similar or better effects. Note that among the above-mentioned surfactants, the phosphoric acid type surfactants may be a mixture of primary and secondary phosphates.

It has been confirmed that sufficient or better leakage resistance can be obtained using the same starting material and indium hydroxide having the same properties as shown in the above examples.

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 and a hydroxide having an appropriate crystal type by an appropriate synthesis method are used. By adding indium, even without mercury, it is possible to suppress the increase in battery internal pressure due to corrosion of zinc and improve the leakage resistance of the battery. By adding an appropriate amount of an organic 2-inhibitor having an appropriate structural formula 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. 1... Positive electrode mixture, 2... Gel-like negative electrode, 3... Name of separator agent Patent attorney Shigetaka Awano and 1 other person

Claims (1)

[Scope of Claims] (1) In the preparation of a gelled negative electrode in which zinc alloy powder is mixed and dispersed in a gelled alkaline electrolyte, a zinc alloy containing at least one member from the group consisting of indium, lead, bismuth, calcium, and aluminum. was used as the active material, and in the alkaline electrolyte, the following properties were observed in the X-ray diffraction diagram: 4.71±0.10 Å, 3.98±0.02 Å, 3.5
Indium hydroxide showing peaks at 7±0.10 Å and 2.66±0.02 Å was added to the zinc alloy at 0.0
A method for producing a zinc-alkaline battery, characterized in that the zinc-alkaline battery contains 0.05 to 0.5 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, in the X-ray diffraction diagram, 4.71±0.10 Å, 3.98±0.02 Å, 3.5
Indium hydroxide showing peaks at 7±0.10 Å and 2.66±0.02 Å was added to the zinc alloy at 0.0
05 to 0.5 wt % of the zinc alloy, and further containing 0.001 to 0.1 wt % of a surfactant having polyethylene oxide in its hydrophilic part based on the zinc alloy. (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.