JPS63239769A - Zinc alkaline cell - Google Patents

Abstract

PURPOSE:To make it possible to decrease the gelatinization rate of a negative electrode of a zinc alkaline cell by using a specific anticorrosive as an anticorrosive to suppress the corrosion of the negative electrode. CONSTITUTION:As an anticorrosive for a negative electrode active material, polyoxyethylene phenylether and a derivative shown in the formula (I), in which the functional end group of the polyoxyethylene phenylether is replaced with a phosphoric acid radical, sulfuric acid radical, or methylenecalboxylic acid, and at least one selected from salt group the above derivatives are neutralized with an alkaline metal are used. The polymerization rate of the oxyethylene in the anticorrosive is preferable to be 1 to 70. By using such an anticorrosive, a remarkable anticorrosive effect is observed and the gelatinization of the negative electrode can be decreased.

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 provides an effective means for reducing the amount of mercury used in hydration of the zinc negative electrode of zinc alkaline batteries using mercury oxide, oxygen, nickel hydroxide, etc.

Conventional technology In order to suppress the corrosion of the electrolyte of the zinc negative electrode, 7
A method of adding ~10% by weight of mercury to zinc has been adopted industrially. However, in recent years, there has been an increasing social need to reduce mercury content in order to reduce pollution, and various corrosion-resistant zinc alloys have been developed or proposed to ensure sufficient corrosion resistance with the use of small amounts of mercury. . For example, a corrosion-resistant zinc alloy powder made by adding indium, lead, gallium, aluminum, etc. to zinc is considered to be effective, and a nine-zinc alloy with the addition of indium and lead has already been put into practical use.In order to further improve corrosion resistance, indium.

A zinc alloy to which aluminum and, if necessary, gallium are added in addition to lead is being considered as a typical example.

When these corrosion-resistant zinc alloys are used, corrosion resistance can be ensured even if the hydration rate (the weight percentage of mercury in negative electrode zinc) is reduced, and in the case of zinc alloys containing indium and lead, the hydration rate is a Furthermore, in the improved zinc alloy mentioned above, in which aluminum is added in addition to indium and lead, and gallium is added as necessary, even a hydration rate of about 1.5% is equivalent to the hydration rate of 7 to 10% in the case of pure zinc. Provides corrosion resistance.

As can be seen in the above examples, it is clear that using a corrosion-resistant zinc alloy is effective 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 acids, amine naphthalene sulfonic acids, azonaphthalenes, and carbazole have been used to prevent corrosion of zinc negative electrodes in alkaline aqueous electrolytes.

Application of various anticorrosive agents has been proposed, including cyanohydrin, thiazole derivatives such as 2-meltocaptobenzothiazole, and derivatives of benzotriazole. The general application method is to add a small amount of these anticorrosive agents to the electrolyte. However, none of the anticorrosive agents has been found to have a significant anticorrosive effect, and currently they are not effective means for reducing the hydration rate.

Problems to be Solved by the Invention If the corrosion protection of the zinc negative electrode is insufficient, hydrogen gas will be generated as zinc is consumed during storage in the W1 pond, and the internal pressure of the battery will rise, leading to leakage of electrolyte and deformation of the battery. In severe cases, it may cause the battery to explode. Moreover, corrosion of zinc is IE
It can also cause deterioration of battery performance after storage, such as a decrease in the capacity of the pond. The object of the present invention is to ensure sufficient corrosion resistance of a zinc negative electrode to prevent the occurrence of the above-mentioned problems while minimizing the corrosion rate. As a way to do this, we will search for a new anticorrosive agent that has a greater anticorrosive effect than the various anticorrosive agents previously proposed, is alkali resistant, and has no negative impact on discharge performance, and will create a zinc anode with a low water reduction rate. Applicable to ready-made batteries, without impairing the battery characteristics of practical batteries.
The present invention provides a low-pollution zinc-alkaline battery with a low mercury content.

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 zinc and zinc as the negative electrode active material.
Or zinc alloy, manganese dioxide, silver oxide as positive electrode active material,
Polyoxyethylene phenyl ale (@-0(-CH2-OH2→÷YH)) and its terminal Derivatives whose functional groups are substituted with phosphonic acid groups, sulfonic acid groups, or methylenecarboxylic acid groups (G tomo CH2-CH2→9PO3H2゜■-〇 +c
H2-CH2-C8-nCH2COOH"J, and salts of these derivatives neutralized with alkali metals, for example,
(■Hio+aH2-CH2-01, p o 3L, .

C→-1-CH2-CH2-0chinSO3Na.

(Σto0(-CH2-CH2-0-)-nCH2COO
At least one selected from the group of Li is used.

The method of applying these anticorrosive agents is to add them to the electrolyte.

Methods such as impregnation into both or one of the separator and the liquid retaining material, and attachment to the surface of the negative electrode active material can be adopted. Also,
Oxyethylene (CH2-CH2-0-
) preferably has a degree of polymerization (n) of 1-70.

Furthermore, although pure zinc or a zinc alloy is used as the negative electrode active material, it is particularly effective to use a corrosion-resistant zinc alloy and the above-mentioned anticorrosive agent in combination to achieve a significant reduction in the hydration rate. for example,
A battery with sufficient corrosion resistance of the negative electrode can be obtained even at a hydration rate of 0.2% by using a zinc alloy with the addition of lead, or a zinc alloy with the addition of gallium. Elements plus aluminum, strontium.

0.0 when used in combination with a zinc alloy containing at least one of calcium, magnesium, barium, and nickel
Corrosion resistance of the negative electrode can be ensured even at a hydration rate of 5%.

Effect The mechanism of action of the anticorrosive agent used in the present invention is unclear, but is presumed to be as follows.

The anticorrosive agent of the present invention has a nearly linear molecular structure and has an acidic aqueous alkyl group, and when added to an electrolyte, it dissolves or disperses and the polar group adsorbs to the surface of zinc or zinc alloy of the negative electrode. considered to be a thing. Zinc alkaline! The corrosion reaction in the liquid is shown by the following formula, and when the anticorrosive agent is adsorbed to the negative electrode surface and forms a film, the anode reaction Zn+40H--h Zn(OH)
+2e-cathode reaction 2J(20+2e″″ −+
This prevents hydroxide ions, which cause the 20H'''+H2 anode reaction, from approaching the zinc negative electrode, and also prevents the water molecules necessary for the cathode reaction from existing near the zinc alloy surface, preventing corrosion of the zinc alloy. Even if the amount of corrosion inhibitor is small and does not completely cover the surface of the zinc negative electrode, the corrosion reaction of zinc at the adsorption part of the added corrosion inhibitor on the surface of the zinc negative electrode is suppressed, and the total amount of corrosion of the zinc negative electrode is reduced.゛Also, even if the anticorrosive agent is added by impregnating it into the separator and/or liquid retaining agent, or attaching it to the surface of the negative electrode active material, the anticorrosive agent will be dissolved or dispersed in the electrolyte after battery construction, and the same problem as above will occur. is adsorbed onto the surface of the zinc negative electrode, suppressing zinc corrosion.As described above, it is thought that the anticorrosive agent used in the present invention has a corrosion-preventing effect because it covers the surface involved in the corrosion reaction of zinc. Kaisho 5
8-18266, or JP-A-60-175368, JP-A-61-77267, JP-A-61-181058, JP-A-61-203563, JP-A-61- The zinc alloys disclosed by the inventors in No. 150307 etc. that contain indium and lead and further contain one or more selected from the group of gallium, aluminum, strontium, calcium, magnesium, barium, and nickel have excellent corrosion resistance. However, if the corrosion rate is reduced to about 0.2%, sufficient corrosion resistance cannot be ensured. However, when the above-mentioned anticorrosive agents are used together, the anticorrosion effects of both are combined, and in some cases, the anticorrosion effect is 0.
Corrosion resistance of the negative electrode is ensured even at a filtration rate of 0.05%.

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.

This will be explained in detail below using examples.

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 a conventional anticorrosive agent in an electrolytic solution containing zinc oxide dissolved in an aqueous solution of potassium hydroxide weighing 40% by weight to almost saturation level, collect 5d, and add ice to the solution. 101 ml of zinc chloride powder was charged, and the amount of hydrogen gas generated over 20 days at a temperature of 45° C. was measured. The hydration rate of hydrated zinc powder is 1.0, and the particle size is 35
~150 meshes. The measurement results obtained are shown in Table 1.

In Table 1, the groups 1 to 24 using the anticorrosive agent of the present invention are the groups 25 to 2 using the anticorrosive agents proposed in the past.
It can be seen that the amount of hydrogen gas generated in Group 70 and Group 528 to which no anticorrosive agent was added was small, indicating that the corrosion inhibiting effect of the anticorrosive agent of the present invention is large. Among the &1 to 240 groups, /&1 to 9 are those in which the degree of polymerization of oxyethylene as an anticorrosive agent is unified to 10, and differences in anticorrosive effect due to the type of terminal functional group and neutralization with an alkali metal are investigated. Both have great anti-corrosion effects,
Among them, A2 whose terminal group is -Po3H2 is judged to be the best. & 10 to 13 are results in which the anticorrosion effect was investigated when the degree of polymerization of oxyethylene was changed for those having -Po3H2 as a terminal group.

As can be seen by comparing /Pa2 and Washing 10 to 13, among those with an oxyethylene polymerization degree of 1 to 100, one case 7o
If the items (Cursed 2 and 5 10 to 12) are additive-free (7
628) shows the following hydrogen gas generation amount, which is particularly good. Examples A14 to A24 and E2 show that other anticorrosives of the present invention also have anticorrosive effects within the same range of polymerization degree.
This is clear from a comparison with the conventional example of 5-2T and the case of no additive of 7f128.

Example 2 Next, based on the results obtained in Example 1, a typical anticorrosive agent was selected, and the button-shaped oxidation agent shown in Fig. 1 was evaluated for its effect on reducing the corrosion rate of zinc or zinc alloy, which is the negative electrode active material. We made a prototype silver battery and conducted a comparative study. 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 zinc oxide is saturated in a 40 weight aqueous solution of potassium hydroxide (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 all carboxymethyl cellulose. This is a zinc negative electrode in which 50 to 150 meshes of powder of frozen zinc or hydrated zinc alloy are dispersed in this gel. 3 is a cellulose-based liquid retaining material,
4 is a porous polypropylene ring separator, 5 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 envy. It is a positive electrode can. 8 is a polypropylene ring gasket that prevents the positive electrode can 7 from being bent.
and the sealing plate 1. The prototype battery has a diameter of 11.6 am and a total height of 6.4 cm.

I made a prototype! Table 2 shows the changes in discharge performance and total battery height after storage at 60'C in a pond for one month, and the number of batteries in which leakage was observed by visual inspection. The discharge performance was expressed as the discharge duration when discharging at 610Ω at 20°C with a final voltage of o, sV.

Normally, in a normal button battery, after the battery is sealed, the total height of the battery will decrease slightly over time until the stress relationship between each battery component stabilizes. In a battery that generates a large amount of gas, the total height of the battery tends to increase due to an increase in the internal pressure of the battery. 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 not only increase the total height of the battery, but also tend to leak due to an increase in battery internal pressure, and also deteriorate discharge performance (due to consumption of negative electrode zinc due to corrosion (1) surface oxidation. From this point of view, the prototype experiment results shown in Table 2 are evaluated as follows. First, Zinc has extremely good corrosion resistance as a negative electrode active material, and if it has a corrosion rate of 1.5 or more, it is considered promising to be used as a negative electrode in practical batteries without the aid of anticorrosive agents. A battery was constructed using an alloy (a zinc alloy containing Pb, In, and AI) with an extremely low water content of 0.05 wt%, and the effects of the anticorrosive agent were compared. These results show that in the case of washes 1 to 7 to which the anticorrosive agent of the present invention was added, A8
It was shown that the corrosion resistance of the conventional examples of ~10 to 10 was significantly better than that of the case without addition or no addition, and by using the above corrosion-resistant zinc alloy and the corrosion inhibitor of the present invention in combination, the corrosion rate of O,OS% or more was achieved. This shows that it is possible to ensure sufficient corrosion resistance of the negative electrode and to construct a zinc-alkaline battery with an extremely low rate of deterioration.

In addition, Washi 11 to 18 are currently popular materials with a rate of 3%.
By reducing the hydration rate of zinc alloy (zinc alloy containing Pb and In), which has been put into practical use with a hydration rate of 0.2%,
The effect of the anticorrosive agent of the present invention was investigated. In this case as well, there is a clear difference in battery performance between Examples A11-16 and the conventional example of Todoroki 16-18 or the case without additives.
If the above zinc alloy and the anticorrosion agent of the present invention are used together, 0.2w
This shows that it is possible to construct a zinc-alkaline battery with a low water conversion rate that has sufficient corrosion resistance of the negative electrode and excellent practical performance when the water conversion rate is t% or more. Furthermore, black 19-26 is usually 7-10%
It was shown that when pure zinc powder, which requires a hydration rate of about 100%, is used as a negative electrode active material, it is possible to construct a battery with sufficient practicality even if the hydration rate is reduced to a very low level by applying the present invention. ing. In addition, 527-38 are zinc alloys with a hydration rate of 1,5-3, which can ensure the corrosion resistance of the negative electrode without the aid of anticorrosive agents. The effect of the present invention was confirmed by Kanakura when used as a negative electrode. The properties were further improved compared to the previous case, indicating that the quality was stabilized by ensuring a high degree of corrosion resistance.

Figure 39.40 is a test of the effect of the present invention using a zinc alloy containing Pb, In, and Ga with a hydration rate of 0.2%, which has almost the same corrosion resistance as a zinc alloy containing Pb and Inl. In the example of 1611-16 Pb, I
This shows that a hydration rate of 0.2 h can be achieved, similar to the example with the zinc alloy containing n.

441-50 is expected to be a completely blind zinc alloy with almost the same corrosion resistance as a zinc alloy with improved corrosion resistance containing Pb, In, and Al'e, and has a hydration rate of 0.05.
The sound effects of the present invention were investigated in terms of wt%, and in all Examples (A41, 43.45, 47, 49), even with a low water content of 0.05%, 41 Similar to the previous examples, it shows excellent current performance. In all of the above cases, the effects of the present invention were fully investigated by dissolving the anticorrosive agent in the electrolytic solution.
No. 1, 52.53 shows an example of the present invention other than the method of adding an anticorrosive agent to the electrolytic solution. Both A52 and A53, in which the separator or liquid retaining material was completely impregnated with the anticorrosive agent, had almost the same effect as when the anticorrosive agent was dissolved in the electrolyte. In all of these cases, according to the battery composition theory, the anticorrosive agent gradually dissolves in the electrolyte and exerts an anticorrosive effect.
In particular, when the separator or liquid-retaining material is impregnated with an anticorrosive agent, the electrolyte penetrates quickly, which facilitates battery construction and increases productivity.

Example 3 Next, Go(-CH2-CH2-0÷1°PO3H2'r selection i) was used as a typical anticorrosive agent.
, J.: , ``The relationship between dissolved concentration in electrolyte and ice formation'' was investigated using a corrosive meter for powder.

The frozen zinc alloy powder contains 0.05w each of Pb, In, and Ale.
10) Weighed 35 to 150 meshes of zinc alloy powder containing 35 to 150 meshes of potassium hydroxide, which was frozen by dropping mercury in an alkaline solution at a viscosity rate of 0.05 wt%. It was immersed in an electrolytic solution S aa in which zinc oxide was saturated in a wt% aqueous solution and an anticorrosion agent was dissolved, and the temperature was 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 FIG.

As seen in Figure 2, a remarkable effect is seen when the concentration of (Dato(-0M2-CH2-041°PO3H2) is about 500 ppm or more,
Above about 1000p pm, the soil concentration is about 3800p.
A nearly constant effect can be obtained up to pm. In addition to this anticorrosive, the anticorrosives used in A1 to A7 of Example 1 were also
A similar effect was observed, and it was found that the appropriate concentration of the anticorrosive agent of the present invention is preferably from about 100 ppm or more to less than the saturation concentration.

Effects of the Invention The present invention has made it possible to significantly reduce the overall filtration rate of the negative electrode of a zinc-alkaline battery through the effect of a newly discovered anticorrosive agent.

[Brief explanation of drawings]

Figure 1 shows a cross section 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 anticorrosive 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. Name of agent: Patent attorney Toshio Nakao and 1 other person2-
11 Ako Neikyo =>----1 Paleta

Claims (7)

[Claims] (1) Polyoxyethylene phenyl ether is used as an anti-corrosion agent for negative electrode active materials ▲ There are 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 A zinc-alkaline battery using at least one selected from the group of salts prepared by neutralizing these derivatives with an alkali metal. (2) The zinc alkaline battery according to claim 1, wherein the degree of polymerization of oxyethylene as the anticorrosive agent is 1 to 70. (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%.