JPS63276871A - Zinc alkali cell - Google Patents

Abstract

PURPOSE:To secure anti-corrosiveness with the amalgamation ratio held low by selecting the negative electrode anti-corrosive agent from a group containing polyoxyethylene-slkyphenylether, derivatives formed by substitution of its end functional group with a certain acid radical, and salts obtained through neutralization of these derivatives. CONSTITUTION:As anti-corrosive agent for a negative electrode active substance is used at least one of the following: polyoxyethylene-alkyphenylether Eq. I, derivatives Eq. II-IV obtained by substituting its end functional group with phosphonic acid radical, sulfonic acid radical, or methylenecarboxylic acid radical, and salts obtained by neutralizing these derivatives with alkali metal, for ex., Eq. V. Application of any of these anti-corrosive agents is made by means of addition to electrolyte liquid, impregnation in either or both of the separator and liquid retaining material, and affixation to the surface of negative electrode active substance.

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 mankaline dioxide, silver oxide, mercury oxide, oxygen, nickel hydroxide, etc. as a positive electrode active material. The present invention provides an effective means for reducing the amount of mercury used in the hydration of the zinc negative electrode of the zinc alkaline battery used.

Conventional technology In order to suppress corrosion of the electrolyte of the zinc negative electrode, T
A method of adding mercury of about 10 to 10 weight fl-h to zinc has been adopted industrially.However, in recent years, in order to reduce pollution,
As social needs for reducing mercury content increase, various corrosion-resistant zinc alloys have been developed or proposed in order to ensure sufficient corrosion resistance with the use of small amounts of mercury. For example, corrosion-resistant zinc alloy powder, which is made by adding indium, lead, gallium, aluminum, etc. to zinc, is considered to be effective. Zinc alloys containing indium and lead have already been put into practical use, and in order to further improve corrosion resistance, indium.

In addition to lead, a zinc alloy containing aluminum and, if necessary, gallium is being considered as a typical alloy.
When these corrosion-resistant zinc alloys are used, corrosion resistance can be ensured even if the hydration rate ('11 amount percentage of mercury in negative electrode zinc) is reduced, and in the case of zinc alloys with indium and lead added, the hydration rate is 3. %, the above indium which is further improved,
In the case of a zinc alloy in which aluminum and, if necessary, gallium are added in addition to lead, a corrosion resistance equivalent to that of pure zinc can be obtained even when the corrosion ratio is about 1.6 cm.

As seen in the above example, it is effective to use a corrosion-resistant zinc alloy as a method of reducing the corrosion rate.
Another effective method is to add an anticorrosive agent, and the combination of a corrosion-resistant zinc alloy and an anticorrosive agent is considered essential as a technique for reducing the mercury content in batteries to the utmost limit.

Conventionally, glycols such as ethylene glycol, mercaptocarboxylic acid, aminonaphthalene sulfonic acid, azonaphthalenes, and carbazole have been used to prevent corrosion of zinc negative electrodes in alkaline aqueous electrolytes.

A wide variety of anticorrosive agents have been proposed to be used. The general method of application of these anticorrosive agents is to add a small amount to the electrolyte.However, none of the anticorrosive agents have been found to have a significant anticorrosion effect, and it is not an effective means to reduce the hydration rate. The current situation is that this is not the case.

Problems to be Solved by the Invention If the corrosion protection of the zinc negative electrode is insufficient, hydrogen gas will be generated as the zinc is consumed during storage of the battery, and the internal pressure of the battery will increase, causing leakage of electrolyte and deformation of the battery. In severe cases, it may cause the battery to explode. Furthermore, corrosion of zinc also causes deterioration in battery performance after storage, such as a decrease in battery capacity. The purpose of the present invention is to ensure corrosion resistance of a zinc negative electrode sufficient to prevent the occurrence of the above-mentioned problems while minimizing the hydration rate. It has a greater anti-corrosion effect than various anti-corrosive agents.
We have searched for a new anticorrosive agent that is resistant to alkali and has no negative impact on discharge performance, and applied it to batteries with zinc negative electrodes with low hydration rates. The present invention provides a low-pollution zinc-alkaline battery with low energy consumption.

Means for Solving the Problems The present invention uses an alkaline aqueous solution containing potassium hydroxide, sodium hydroxide, etc. as the main components as an electrolyte, and a semi-soft yellow as a negative electrode active material.
is a zinc alloy, and the positive electrode active materials include manganese dioxide, silver oxide, oxygen, and nickel oxyhydroxide.

Selected from the group of crocodile conductors in which polyoxyethylene alkylphenyl ether terminal functional groups are substituted with phosphonic acid groups, sulfonic acid groups, or methylene carboxylic acid groups as an anticorrosive agent to suppress corrosion of the negative electrode of so-called zinc alkaline batteries using mercury oxide etc. At least one of the following methods shall be used. These anticorrosive agents can be applied by adding them to an electrolytic solution, impregnating them into both or one of a separator and a liquid retaining material, and attaching them to the surface of a negative electrode active material. In addition, the above-mentioned anticorrosive agent has a carbon number of 1 to 3 o in the alkyl group (6), a polymerization degree (b) of oxyethylene (CH2-CH2-o-) of 1 to 40, and R++C% -CJ-0. Those having a chemical formula weight of 263 to 1979 are preferred.

In addition, although pure zinc or a zinc alloy is used as the negative electrode active material, it is effective to use a corrosion-resistant zinc alloy and the above-mentioned anticorrosive agent in combination with the above-mentioned anticorrosive agent, especially in order to achieve a significant reduction in the corrosion rate.
When used in combination with a zinc alloy to which indium and lead are added, or a zinc alloy to which gallium is added, a battery with sufficient corrosion resistance of the negative electrode can be obtained even at a hydration rate of 0.2 cm. In addition, aluminum, Stro 7F
') Jh.

When combined with a zinc alloy containing at least one of calcium, magnesium, barium, and nickel, o, os
Corrosion resistance of the negative electrode can be ensured even at a hydration rate of 1. Function The mechanism of action of the anticorrosive agent used in the present invention is unclear, but it is inferred as follows.

The anticorrosive agent of the present invention has a nearly linear molecular structure, with a polar group such as a hydroxyl group, a phosphonic acid group, a sulfonic acid group, or a methylenecarboxylic acid group at one end, and a hydrophobic alkyl group at the opposite end. The corrosion reaction of zinc in an alkaline electrolyte is shown by the following equation: However, when the anticorrosive agent is adsorbed to the negative electrode surface and forms a film, an anode reaction Zn+40H'''-+Zn(OH)4
+2@force sword reaction 2H2042・-→201(-+H
The hydroxide ions that cause the 2-anode reaction approach the zinc negative electrode, and the water molecules necessary for the cathode reaction cannot exist near the surface of the zinc negative electrode, suppressing corrosion of the zinc.・Anti-corrosion agent Even if the added corrosion inhibitor is small and does not completely cover the surface of the zinc negative electrode, the corrosion reaction of zinc at the adsorbed part of the zinc negative electrode surface is suppressed, and the total amount of corrosion of the zinc negative electrode is reduced. Even if it is added by impregnating the separator and/or liquid holding column, or adhering to the surface of the negative electrode active material, the anticorrosive agent will dissolve or disperse in the electrolyte after battery construction and will be applied to the surface of the zinc negative electrode in the same way as above. It is adsorbed and corrosion of zinc is suppressed. As described above, it is believed that the anticorrosive agent used in the present invention has an anticorrosion effect because it covers the surface related to the corrosion reaction of zinc. , or JP-A-60-17536! I, JP-A-61-772
67.

JP-A-61-181068, JP-A-61-20356
3゜Zinc alloy containing indium and lead, and further containing one or more selected from the group of gallium, aluminum, strontium, calcium, manesium, barium, and nickel, as disclosed by the inventors in Japanese Patent Application No. 150307/1983. Both have excellent corrosion resistance, but when the corrosion rate is 0.2
If the corrosion resistance is reduced to -, sufficient corrosion resistance cannot be ensured.

However, when the above-mentioned anticorrosive agents are used in combination, the anticorrosion effects of both are combined, and in some cases, the corrosion resistance of the negative electrode can be ensured even at a 0.05% corrosion rate.

As mentioned above, the present invention has developed a highly practical zinc-alkaline battery with a low water conversion rate by experimentally examining the corrosion inhibitor that is effective in improving the corrosion resistance of zinc negative electrodes, the differences in their molecular structures, and the use of them in combination with corrosion-resistant zinc alloys. It is completed.

EXAMPLES Example 1 First, the corrosion inhibiting effect of the anticorrosive agent of the present invention on zinc in an alkaline solution was investigated. The experimental method was to dissolve the anticorrosive agent of the present invention or the conventional anticorrosive agent in an electrolytic solution containing zinc oxide in a 40% potassium hydroxide aqueous solution to almost saturation point B-, and then add ice to the solution. The amount of hydrogen gas generated in 20 days at a temperature of 46°C was measured by adding 102% of zinc chloride powder.
It was set to 6 to 160 meshes. The measurement results obtained are shown in Table 1.

Table 1 In Table 1, groups 1 to 29 using the anticorrosive agent of the present invention are group 430 to 3 using the anticorrosive agent proposed conventionally.
It can be seen that the amount of hydrogen gas generated is smaller than Group 20 and 433 to which no anticorrosive agent is added, indicating that the corrosion inhibiting effect of the anticorrosive agent of the present invention is large. Among the groups of /fL1 to 29, Graves 1 to 9 are The number of carbon atoms in the alkyl group of the anticorrosive agent is 9. The degree of polymerization of oxyethylene was standardized to 10, and the difference in anticorrosion effect due to the type of terminal functional group and neutralization with alkali metal was investigated.

All have a great anticorrosion effect, especially when the terminal group is -PO3
)12, which was determined to be the best. A10-17
As can be seen by comparing 042 and 410-17, which is a study of the anticorrosion effect when changing the number of carbon atoms in the alkyl group and the degree of polymerization of oxyethylene for those with -PO3H2 as the terminal group. The number of carbon atoms in the alkyl group is 1 to 3o, and the degree of polymerization of oxyethylene is 1 to 4.
Among those with a molecular formula weight of 263 to 197G (A2 and 4611
~16) shows a hydrogen gas generation amount of H or less in the case of no addition of 433, which is particularly good.@The same carbon number 1 polymerization degree is also found for other anticorrosive agents of the present invention.

The anticorrosion effect within the molecular formula weight range is A18-29.
This is clear from the comparison between the examples of &30 to 33 and the conventional examples and cases without additives.Example 2 Next, based on the results obtained in Example 1, one typical anticorrosive agent was used. In addition, a button-shaped silver oxide battery as shown in FIG. 1 was prototyped to compare and examine the effect of zinc or zinc alloy, which is the negative electrode active material, on reducing the oxidation rate. In FIG. 1, reference numeral 1 denotes a sealing plate made of stainless steel, the inner surface of which is plated with copper. 2 is an electrolytic solution in which a 40% by weight aqueous solution of potassium hydroxide is saturated with zinc oxide (if an anticorrosive agent is added, an electrolytic solution in which a saturation amount of the anticorrosive agent shown in Table 2 is dissolved) is gelled with carboxymethyl cellulose. This is a zinc negative electrode in which 60 to 160 meshes of powder of zinc hydrate or zinc oxide alloy are dispersed in this gel. 3 is cellulose-based liquid retaining material, 4
6 is a porous polypropylene group separator, 6 is a positive electrode made of a mixture of silver oxide and graphite and pressure molded, 6 is a positive electrode ring made of nickel-plated iron, and 7 is a nickel-plated stainless steel positive electrode can. be. Reference numeral 8 denotes a polypropylene gasket, which is compressed between the positive electrode can T and the sealing plate 1 by bending the positive electrode can. The prototype nine batteries have a diameter of 11.6w and an i%! Table 2 shows the changes in discharge performance and total battery height of prototype batteries with high 5*4+w after being stored at 60°C for one month, as well as the number of batteries in which leakage was observed by visual inspection. The discharge performance was expressed as the discharge duration when discharging at 201: s1oΩ with a final voltage of 0.9V.

Table 2 In a normal button battery, after sealing the battery, the total height of the battery will decrease slightly over time until the stress relationship between each battery component stabilizes, but hydrogen gas due to corrosion of the negative electrode zinc In batteries where a large amount of oxidation occurs, there is a strong tendency for the total battery height to increase due to an increase in battery internal pressure. Therefore, the corrosion resistance of the negative electrode zinc can be evaluated by the increase or decrease in the total height of the battery during the storage period. Batteries with insufficient corrosion resistance will not only increase the total height of the battery, but also be susceptible to liquid leakage due to an increase in battery internal pressure, and discharge performance will also deteriorate due to depletion of negative electrode zinc due to corrosion (2) and oxidation of the surface.

From this point of view, the prototype experiment results shown in Table 2 are evaluated as follows. First, 41 to 10 are zinc alloys that have extremely good corrosion resistance as negative electrode active materials, and are considered promising for use as negative electrodes in practical batteries without the aid of anticorrosive agents, if the corrosion rate is 1.6% or higher. The effectiveness of the anticorrosive agent was compared by constructing a battery using a zinc alloy (containing Pb, In, and An) with an extremely low reduction rate of o and osti. These results show that the cases of I&1 to 7 to which the anticorrosive agent of the present invention was added are much better than the cases of I&8 to 1o with or without the conventional anticorrosive agent. 0.05 by using the alloy and the anticorrosive agent of the present invention together.
% or more, it is possible to ensure sufficient corrosion resistance of the negative electrode, indicating that a zinc-alkaline battery with an extremely low corrosion rate can be constructed. In addition, / 11 to 18 are zinc alloys (Pb
The effect of the anticorrosive agent of the present invention was investigated by reducing the corrosion rate of a zinc alloy containing In to 0.2 inches. In this case as well, the examples of /1611-16 are 416-
In conventional example 2 of No. 18, there is a clear difference in battery performance between the case without additives and the corrosion resistance of the negative electrode when the above zinc alloy and the anticorrosive agent of the present invention are used together at a corrosion rate of 0.2 inches or more. This shows that it is possible to construct a zinc-alkaline battery with sufficient practical performance and a low rate of depletion. Furthermore, A19-26 is usually 7-
When using zinc powder as a negative electrode active material, which requires a filtration rate of about 10, by applying the present invention, it is possible to construct a battery with sufficient practicality even if the filtration rate is reduced to 3. It shows.

9. For A2T~36, the corrosion resistance of the negative electrode can be almost achieved without the help of anticorrosion agent. Just to be sure, the effect of the present invention is confirmed when a zinc alloy with a filtration rate of 1,5 to 3% is used for the negative electrode. This has been confirmed, and in the case of Examples 427-29 and 33-36, 1630-32. The properties were further improved compared to the conventional examples of flats 36 to 38 or the cases without additives, indicating that the quality was stabilized by ensuring a high degree of corrosion resistance.

439.40 has almost the same corrosivity as a zinc alloy containing PB and In. The effect of the present invention was investigated using a zinc alloy containing Pb, In, and Ga with a hydration rate of 0.2%.
This shows that it is possible to achieve a filtration rate of 0.2 cm, similar to the example using the zinc alloy containing In.

441-50 is expected to be a zinc alloy having almost the same corrosion resistance as a corrosion-resistant zinc alloy containing Pb, In, and AX, and has a corrosion rate of 0.05%.
The effects of the present invention were investigated in Examples 44 and 44.
1, 43, 48, 47, 49) also showed excellent battery performance even at a low hydration rate of o, ose, similar to the A1-A example using a zinc alloy containing Pb, In, and AJ. ing. All of the above cases are the results of examining the effects of the present invention by dissolving an anticorrosive agent in the electrolyte, but 451
．． 52 and 53 show an example of the present invention other than the method of adding an anticorrosive agent to the electrolytic solution. 452.53 impregnated with the anticorrosive agent had almost the same effect as when the anticorrosive agent was dissolved in the electrolytic solution. In all of these cases, the anticorrosive agent gradually dissolves into the electrolyte after the battery is constructed, exerting its anticorrosive effect. In particular, when the separator or liquid retaining material is impregnated with the anticorrosive agent, the anticorrosion agent gradually dissolves into the electrolyte after the battery is constructed. Since penetration becomes faster, battery construction becomes easier and productivity is increased.

Example 3 Next, the relationship between the concentration of a typical anticorrosive agent dissolved in an electrolytic solution and the amount of corrosion of icy zinc alloy powder was investigated.

The frozen zinc alloy powder contains Pb, In, and A1 in o and osl respectively.
A 36 to 180 mesh powder of a zinc alloy containing 36 to 180 tons of powder was made into a mercury in an alkaline solution using a mercury dropping method at a filtration rate of 0.05%, the 105F was weighed, and 40 wt* of potassium hydroxide was Immerse in 6CL electrolyte solution, which is an aqueous solution saturated with zinc oxide and dissolved in anticorrosion agent.

The sample was left to stand at 46°C for 10 days, and the amount of hydrogen gas generated during that time was measured.

The concentration of the anticorrosive agent in the electrolytic solution was adjusted by mixing an electrolytic solution saturated with the anticorrosive agent and an electrolytic solution containing no anticorrosive agent at an appropriate ratio. The results are shown in Figure 2.

As seen in FIG. 2, 09H19()0+CHfH2-0-). PO3H2
A remarkable effect is seen when Ow1 degree is about s o o ppm or more, and at about 11,000 ppm or more, the saturation concentration of about 42
A substantially constant effect can be obtained up to oOppm. In addition to this anticorrosive agent, the anticorrosive agents used in I&1 to 7 of Example 1 had similar effects, indicating that the anticorrosive agent of the present invention is appropriate! It has been found that it is preferable for the I change to be from about 11,000 pp or more to less than the saturated # change.

Effects of the Invention The present invention makes it possible to significantly reduce the hydration rate of the negative electrode of a sand-zinc alkaline battery through the effect of a newly discovered anticorrosive agent.

[Brief explanation of the drawing]

Figure 1 is a partially sectional side view of a button-shaped silver oxide battery used in an example of the present invention, and Figure 2 shows the relationship between the amount of anticorrosion agent dissolved in the electrolyte and the amount of hydrogen gas generated. It is a diagram. 2...Zinc negative electrode, 4...Separator,
6...Silver oxide positive electrode.

Claims (7)

[Claims] (1) As anticorrosive agents for negative electrode active materials, there are polyoxyethylene alkylphenyl ethers▲mathematical formulas, chemical formulas, tables, etc.▼, and derivatives whose terminal functional groups are substituted with phosphonic acid groups, sulfonic acid groups, or methylenecarboxylic acid groups ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and selected from the group of salts made by neutralizing these derivatives with alkali metals. At least one type of zinc-alkaline battery. (2) the alkyl group (R) of the anticorrosion agent has 1 to 30 carbon atoms;
The degree of polymerization (n) of oxyethylene is 1 to 40, ▲ formula,
There are chemical formulas, tables, etc. The zinc-alkaline battery according to claim 1, wherein the chemical formula weight of ▼ is 263 to 1979. (3) The zinc-alkaline battery according to claim 1 or 2, wherein an anticorrosive agent is dissolved in the electrolyte. (4) The zinc-alkaline battery according to claim 1 or 2, wherein both or one of the separator and the electrolyte holding material is impregnated with an anticorrosive agent in advance. (5) The zinc-alkaline battery according to claim 1 or 2, wherein an anticorrosive agent is previously attached to the surface of the negative electrode active material. (6) A claim in which a zinc alloy containing indium and lead as essential additive elements and gallium as an optional additive element is used as the negative electrode active material, and the filtration rate of the negative electrode active material is 3 to 0.2%. The zinc-alkaline battery according to any one of items 1 to 5. (7) Using a zinc alloy as a negative electrode active material, which contains indium and lead as essential additive elements, and further contains one or more selected from the group of aluminum, strontium, calcium, magnesium, barium, nickel, and gallium;
The zinc-alkaline battery according to any one of claims 1 to 5, wherein the negative electrode active material has a hydrogenation rate of 1.5 to 0.05%.