JPH0279367A - Electrochemical battery equipped with alkaline electrolyte and zinc negative electrode - Google Patents

Abstract

PURPOSE: To provide a pollution-free battery by making zinc beads contain indium thereon and specifying the amount of content of organic compounds. CONSTITUTION: A battery C is configured, being equipped with a zinc electrode containing, for example, 50ppm of C6 F13 C2 H4 (C2 H4 O)14 OH and 0.2% of Indium. Hereat although the battery C has a smaller content of a stabilizing chemical compound compared to battery A; the battery C has a rate of zinc corrosion of 1μl/gd, its discharge characteristics shows a remarkably improved discharging, and the drop in voltage after 1 hour is not observed. Having thus described the invention, the zinc electrode does not contain mercury, cadmium and lead, but contains indium of 0.005 to 1% by weight, extending on the surface of zinc beads, and also at least one organic stabilizing chemical compound of 1ppm to 1000ppm selected from the group consisting of poly-fluoride compounds of ethoxyfluoro alcohols and compounds of polyethoxy alcohol-alkyls. Thus in an alkaline battery having a zinc negative electrode, a clean battery can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an electrochemical cell with an alkaline electrolyte and a zinc negative electrode, and in particular with zinc/manganese dioxide, zinc/silver oxide or zinc/
Pertains to air-type alkaline-blown ponds.

Although this type of primary cells makes it possible to obtain high energies, due to the corrosive nature of their negative electrodes, which are reactive in alkaline electrolytes, there is a risk of local solubilization of the negative electrodes in the electrolyte during storage. It shows a significant degree of stability degradation manifested as a resulting battery capacity loss. In addition, there is also a continuous release of considerable amounts of gaseous hydrogen, which generates gas pressures that cause the release of electrolyte and sometimes even the rupture of the battery's safety valves. increases in case of an increase in temperature inside.

To prevent this type of phenomenon, for several decades now all battery manufacturers have amalgamated zinc electrodes, sometimes adding cadmium and lead. In fact, mercury and lead are simple and effective means to reduce hydrogen release overpotentials or, in other words, prevent corrosion of the zinc, and cadmium also serves to improve conductivity.

While it is true that these elements, mercury, cadmium, and lead, are introduced in small amounts into each battery, many literatures indicate the dangers posed by the dispersion of these elements into the environment, as well as the risk that these elements may enter the food chain. warning of the grave danger of being rediscovered.

ing. In fact, batteries discarded by consumers suffer two types of fate. On the one hand, it is deposited in garbage dumps or sewage treatment plants, where the battery container protects the taste for a period of time and then corrodes, and the radioactive mercury is leached out by running water.

On the other hand, it is processed in incinerators, where the mercury evaporates and diffuses into the atmosphere with smoke, where it recondenses nearby.

In both cases, mercury returns to the environment.

Although it is often recommended to collect used batteries containing mercury, cadmium or lead, this does not seem to be an immediate solution as it results in condensed waste which is even more dangerous to manage.

It is therefore important to go beyond Rule 4, which generally requires that such metal condensation in batteries be eliminated, and find ways to completely eliminate them.

However, low mercury contents of less than 3% relative to zinc are already insufficient for battery preservation, and various alternative methods have already been tried.

Announcement No. 1958-320 dated April 26, 1958
No. 4 proposes adding various materials including indium to the zinc electrode. French Patent No. FR-A-2511
No. 395 recommends gallium. However, in both cases the corrosion rate was 100 times faster than with the 5% amalgamated zinc electrode, giving unsatisfactory results. It has been found that in addition to the addition of indium or gallium, it is necessary to add lead or cadmium, and also to store a certain amount of mercury.

French Patent No. 111-A-2156662 describes the introduction into batteries of various organic compounds such as jetanolamine, oleic acid, monolauryl ethers, amines, quaternary amine compounds and polymers containing ethylene 4-site. is suggesting. All of these are intended to partially replace mercury.

European Patent Application No. [P-8-020! i No. 783 contains 0.001% to 0.8% by weight of ethylene oxide polymer based on the weight of zinc and 0.005% to 0% by weight.
．． 1ffi discloses a technique for doping with 1% indium. The mercury content of zinc electrodes ranges from 3% to 0% heavy metal.
0.04% by weight, more preferably from about 2% to about 0.08%. Another feature of this patent application is that even when both ethylene oxide polymer and indium are added together, 0.04
% or less is insufficient for the stability of the battery.

In French Patent No. FR-^-256732Q, the applicant discloses a method for stabilizing zinc electrodes by adding 0.01% to 1% by weight of an ethoxylfluoroalcohol-based organic polyfluorinated compound relative to zinc. are doing. The applicant also has French Patent No. FR-A, -2583
No. 580 proposes adding other compounds of the polynidoxyl alcohol-alkyl series in concentrations of from 0.00% to 1% by weight. In the case of 1:1 technology, which solves the zinc corrosion problem, the battery voltage level decreases, and the lower voltage level passes the current requirement, meaning that the higher the current, the lower the voltage. It was observed that

The aim of the present invention is to rectify this drawback and to provide an alkaline battery with a zinc negative electrode that is equivalent to a "clean" battery, i.e. a battery that does not contain any mercury, cadmium and lead, but is amalgamated with 5% zinc. The goal is to provide products that provide the same performance.

The present invention is an electrochemical cell having an alkaline N solute and a zinc negative electrode, wherein the zinc electrode does not contain mercury, cadmium, or lead, and has a concentration of 0.005% to 1% by weight spread over the surface of the zinc particles.
1 containing % indium and further selected from ethoxylfluoroalcohol-based polyfluoride compounds and polynidoxyl alcohol and alcoyl-based compounds.
Contains from ppHl to 11000 pp of at least one organic stabilizing compound.

This surface distribution of indium on the zinc grains depends on how it is contained in the electrode as a liquid phase using a salt of indium such as chloride or preferably indium hydroxide.

This method of inclusion can improve the effectiveness/amount ratio compared to using a zinc-indium alloy.

Preferably, the content of the organic compound is in the range from 10 ppm to 200 ppm, and the content of indium is between 0.03% and 0.2%, based on the first generation of the metal.

As a preferred specific example, the battery of the present invention may have the following content.

Indium 0.03% and organic compound 50ppmu
O,2% and 1100pp〃0.1%
10ppm 0.05% and 10ppm In a first variant embodiment, the organic compound has the following formula (1
) matches.

Co F2o, 1- (CH2), -(CH2CH2
0), -OH where n is in the range 4 to 20, preferably in the range 6 to 8, p is in the range 1 to 10, preferably close to 2, and q
is in the range 3 to 40, preferably in the range 10 to 12.

For example, the expression may be as follows.

CF CH (02H40), OH However, q is close to 12.

It may also contain a mixture of:

C6F 13C2H4 (C2H40) 140 To1 and C, oF 21C2 ['' 4 (C2 To14 0)
140 H This gives the average molecular weight corresponding to the following compound.

C7F15C2H4(C2H40)140H In the second modified example, the organic compound satisfies the following formula (2).

CnF2n-1-(OH2), -(OH20H20
), -OH, where n is in the range of 4 to 20, preferably in the range of 6 to 8, p is in the range of 1 to 10, preferably close to 2,
q ranges from 3 to 40, preferably from 10 to 12.

In a third specific example, the organic compound satisfies the following formula (3).

In a fourth modified example, the organic compound has the following formula (4):
satisfy. - R-8-(CH2) 2- (0-CH2-CH,-)
. -OH, where R is an alkyl group, an aryl group, or an argylaryl group, which may or may not be branched, and n is within the range of 2 to 100.

R is preferably an alkyl group having approximately 12 carbon atoms and/or n is in the range from 2 to 20.

The radical R is branched and in particular constituted by tertiary groups.

Detailed Description Alkaline battery A is constructed without mercury, cadmium and lead, but the negative electrode contains 1100 pp of stabilizing compound CF.
It was composed of pure zinc powder dispersed within a gel that also contained CH(02H40)140H.

The corrosion rate of this electrode in contact with an alkaline electrolyte was first measured. This rate was determined by the amount of hydrogen in microliters evolved per gram (l) of zinc per day (d) at a temperature of 60°C. Prior art cells with zinc have a corrosion rate of approximately 1.5 IIi/gd, which value is accepted in most cases).Battery A has a corrosion rate of approximately 11 J1/ad, which is a very satisfactory value. It is.

The battery is then discharged under harsh conditions, ie through a 5 ohm resistor. The figure shows the corresponding discharge curve A (Y-axis represents voltage (V) in volts, X-axis represents time (h) in hours).

It can be seen that a trough of 60 millivolts appears after one hour.

Prior art alkaline cell B was constructed without organic stabilizing compounds, but the gel contained indium at a concentration of 0.2% by weight of zinc. The corrosion rate of battery B is 30/jj2
/ gd, which is too high for good battery storage. However, discharge curve B is accepted.

In this way, the battery C of the present invention is C6F13C2H4 (C2I"
40) 140 H50pDm and indium 0.2%
It was constructed with a zinc electrode containing.

An alkaline electrolyte solution is placed in a mixer, and the solution is mixed with potassium hydroxide saturated with zinc oxide along with a gelling agent constituted by carboxylic cellulose.

While the mixer is rotating, zinc powder is added, followed by indium chloride concentrate and organic stabilizing compounds. After a few minutes of homogenization, an anodic gel is prepared, which is suitable for storage for several days before use.

Surprisingly, despite the reduced stabilizing compound content compared to the battery, the zinc corrosion rate for battery C was 1111/gd, while the corrosion rate for battery B containing the same proportion of indium was 1111/gd. 30/1111/t) (I).

Discharge curve C shows a marked discharge enhancement and no drop in voltage after 1 hour. Therefore, its capacitance is regulated under strict conditions and its cut-off voltage is high.

Finally, a battery according to the invention was made in the same format as battery C, but the concentration of indium and the amount of stabilizing compounds were much lower: 0.05% indium, iopm of stabilizing compounds.

Corrosion rate is 3pf! , /l)d, and its discharge curve is completely normal.

Thus, even if the amounts of the two additives are extremely small, a surprising binding effect exists between them.

In another embodiment of the cell according to the invention, which has an excellent discharge curve, when the zinc powder is treated with the addition of 0.03% indium and 1100 pp stabilizing compounds, the corrosion rate is
Although ce/ad to 2ρ/(ld), it was observed that the presence of only 0.03% indium resulted in 100 g/gd.

Of course, the present invention is not limited to the above specific examples. Organic compounds 0
6 F1302 H4 (C2H40) 140HLl:
It may also be replaced by one of the other compounds listed above.

Similarly, indium chloride can be replaced with indium hydroxide when making zinc electrodes.

The organic compounds mentioned above, in particular those used as examples, are characterized by their non-toxicity. Their presence can be confirmed by NMR (nuclear magnetic resonance) spectra.

[Brief explanation of the drawing]

The drawing represents the discharge curves of a battery according to the prior art and a battery of the invention. A, B...Prior art alkaline battery, C, D...
...Battery of the present invention.

Claims (16)

[Claims] (1) An electrochemical cell comprising an alkaline electrolyte and a zinc negative electrode, wherein the zinc electrode does not contain mercury, cadmium, or lead, and has a range of 0.005% by weight to 1% by weight spread over the surface of the zinc particles.
% by weight of indium, and further contains from 1 ppm to 1000 ppm of at least one organic stabilizing compound selected from polyfluorinated compounds of the ethoxylfluoroalcohol type and compounds of the polyethoxyl alcohol-alkyl sulfide type. (2) The concentration of the organic compound is 10 ppm to 200 p.
An electrochemical cell according to claim 1, wherein the electrochemical cell is in the pm range. (3) Indium concentration is 0.03% based on metal weight
2. The electrochemical cell of claim 1, wherein the electrochemical cell is in the range of 0.2% to 0.2%. 4. The electrochemical cell of claim 1, comprising 0.03% indium and 50 ppm organic compounds. 5. The electrochemical cell of claim 1, comprising 0.2% indium and 100 ppm organic compound. (6) The electrochemical cell of claim 1, comprising 0.1% indium and 10 ppm organic compound. (7) The electrochemical cell of claim 1, comprising 0.05% indium and 10 ppm organic compound. (8) The organic compound has the following formula (1): C_nF_2_n_+_1-(CH_2)_p-(CH
_2CH_2O)_q-OH (wherein n ranges from 4 to 20, preferably from 6 to 8, p ranges from 1 to 10, preferably close to 2, and q ranges from 3 to 40) range, preferably 1
The electrochemical cell according to claim 1, wherein the electrochemical cell satisfies the following (in the range of 0 to 12). (9) The organic compound has the formula: C_6F_1_3C_2H_4(C_2H_4O)_q
The electrochemical cell according to claim 8, which satisfies OH (wherein q is close to 12). (10) The zinc electrode is C_6F_1_3C_2H_4(C_2H_4O)_1
_4OH and C_1_0F_2_1C_2H_4 (C_2H_4O)
A mixture of _1_4OH and the compound: C_7F_1_5C_2H_4(C_2H_4O)_1
Electrochemical cell according to claim 1, comprising a mixture with an average molecular mass corresponding to _4OH. (11) The organic compound has the formula (2) of F: C_nF_
2_n_-_1-(CH_2)_p-(CH_2CH_
2O)_q-OH (where n ranges from 4 to 20, preferably from 6 to 8, p ranges from 1 to 10, preferably close to 2, and q ranges from 3 to 40) 2. The electrochemical cell according to claim 1, wherein the electrochemical cell satisfies the following: (10 to 12). (12) The electrochemical cell according to claim 1, wherein the organic compound satisfies the following formula (3): ▲There are mathematical formulas, chemical formulas, tables, etc.▼. (13) The organic compound has the following formula (4): R-S-(
CH_2)_2-(O-CH_2-CH_2-)_n-
OH (wherein R is an alkyl group, an aryl group, or an alkylaryl group, which may be branched or unbranched, and n is in the range of 2 to 100). chemical battery. 14. The electrochemical cell of claim 13, wherein R is an alkyl group having approximately 12 carbon atoms and/or n ranges from 2 to approximately 20. (15) The electrochemical cell according to claim 14, wherein the group R is branched. (16) The method for manufacturing an electrochemical cell according to claim 1, wherein indium is contained in the negative electrode as a liquid phase using an indium salt such as chloride or indium hydroxide.