DE1038625B - Galvanic primary element with negative silver electrode and solid, anhydrous electrolyte and process for the production of the electrolyte - Google Patents

Description

The invention relates to primary galvanic elements, which consist entirely of solid components, and batteries, which are composed of a plurality of such elements.

Today's electronics technology often requires a power source of high voltage, but low amperage, and in many applications it is desirable to meet these requirements with the smallest possible battery achieve, whereby the power should be constant over an extended period of time.

The batteries of the present invention show improvements in performance as well as increased performance Storage stability compared to previously known batteries with solid electrolytes. The inventors have also found that their batteries failed by themselves due to significant differences in ambient temperatures are adversely affected. It is also an object of the present invention to provide batteries in which the usual passage of current does not have a polarizing effect.

The properties of a battery with a solid electrolyte depend very much on the composition of the Solid electrolyte, which serves as an ionic conductor between the electrodes of the individual elements. The ionic conductivity of the electrolyte or the mobility of the ions determines the type and extent of the chemical Reactions in the element and thus affects its life, voltage and current.

In most cases it is desirable that the ionic conductivity of the solid electrolyte be high, without the element being short-circuited by the electrolyte. It is also required that the composition of the electrolyte is such that the polarization of the element is as low as possible and is expediently avoided entirely, and that the chemical reaction within the element has no side effect that prematurely destroys or renders ineffective any component.

It has been found that a solid electrolyte can be greatly improved in the above-mentioned directions by incorporating tellurium. The addition of 3 ° to 10 ° / ₀ tellurium to a solid electrolyte results in a significant, lasting increase of the voltage and the current strength. The improvement of the ionic conductivity of a solid electrolyte by tellurium / ₀ is essentially limited to the addition of about 3 to 10 °. Amounts outside this range have no determinable effect, so that the advantages achieved by adding tellurium cannot be ascribed to the conductivity of the tellurium alone. It has also been found that by addition of 5 ° / ₀ tellurium enters the maximum achievable improvement of the electrolyte.

The beneficial increase in the ionic conductivity of a solid electrolyte through the addition of tellurium

Silver electrode and solid, anhydrous electrolyte and method for

Manufacture of the electrolyte

Applicant:

Universal Winding Company,
Cranston, RI (V. St. A.)

Representative: E. Maemecke,

Berlin-Lichterfelde West, Ringstr. 10,

and Dr. W. Kühl, Hamburg 36, patent attorneys

Claimed priority:
V. St. v. America August 2, 1955

Harry C. Lieb and John A. de Rosa,

New York, NY (V. St. A.),
have been named as inventors

2

is below by comparison with the electrical conductivity of pure silver chloride, a common electrolyte in solid condition, shown.

The comparison was made as follows.

Melted pure silver chloride was between two silver strips that were 3 mm apart and were in a porcelain crucible, poured. The crucible was then heated enough to remove the silver chloride to make it well fluid and let it adhere to the silver lining. The silver linings were made with wires and the resistance of the solidified melts was measured at three temperatures. The results are given below:

pure temperature resistance AgCl,
AgCl
AgCl + 0.5 _{"/ o} Te
+ 5% Te 24 ⁰ C
100 ⁰ C
200 ° C
24 ⁰ C
100 ⁰ C
200 ° C
21 ° C
100 ° C
200 ° C 1 · ΙΟ ⁸ Ω
7 7 ΙΟ ⁶
4 x 6 x 10 ^δ
3 · 10 ⁸
1 · 8 · ΙΟ ⁷
2 · 10 ⁵
3 · 1 · 10 ^Β
2 3 ΙΟ ³
0 46 ΙΟ ³

Galvanic elements with solid electrolytes containing halogen silver and with silver electrodes are

809 637/128

knows. From the foregoing results it is clear shows that the addition of tellurium to a silver chloride electrolyte is essential to its ionic conductivity elevated. The increase in the tonic conductivity is not so great, however, that short-circuit through the Electrolyte occurs when the electrolyte is in a thin layer of 0.025 mm between the anode and Cathode of an element is applied. How best to carry out and use the invention is over can be seen in the following examples:

1. To produce a primary galvanic element, first 19 g of silver chloride and 1 g of tellurium were melted to form a solid solution. Silver sheets 0.125 mm thick were fused with this solution on one side. Disks 19 mm in diameter were then punched out of this and their electrolyte _{side was coated with a solution of 2.5 g of CuCl 2} in 10 ecm of methanol, in which 1 g of a 10% dispersion of colloidal graphite in butylene glycol was distributed. The panes were then dried at 110 ° C., whereupon the silver side was painted with silver paint as protection against becoming blind. This blind color is a fine dispersion of silver in a volatile liquid. A thin layer of silver remains when it evaporates. The primary element thus formed thus comprised a negative silver electrode, a solid electrolyte made of silver chloride and tellurium and a positive electrode made of copper chloride and graphite. Six elements of this type were then placed one on top of the other in a plastic tube and unoccupied silver disks were placed at each end of the stack.

ίο to serve as a pole. Silver wires attached to these Discs were soldered on, emerged through the closed ends of the plastic pipe to the outside. The individual elements the thus formed battery were test pressed into contact with each other.

Four other sets of six elements each were made into batteries in a similar manner, the composition of the electrolyte being different in each set. In one case pure silver chloride was used and in the other a melt of silver chloride with 0.01, 0.1 and 0.5 ⁰ Z ₀ tellurium. The five batteries thus obtained were then tested with the following result.

electrolyte

Terminal voltage (volts) with an external resistance of χ Ω Ι 10 "Ω Ι 10 ⁸ Ω Ι 10 · Ω

Short circuit current
(Microampere)

AgCl, pure

AgCl + 0.01% Te
AgCl + 0.1 ⁰ Z ₀ Te
AgCl + 0.5 ° _{/ o} Te
AgCl + 5% Te ..

3.0
2.0
1.8
2.3
3.1

3.0
2.0
1.8
2.3
3.1

2. In a further application of the invention, an electrolyte made of silver bromide with 5 ° / _n tellurium was melted onto one side of a 0.125 mm thick silver sheet in a layer thickness of about 0.025 mm. A disk about 19 mm in diameter was punched from this sheet. Furthermore, filter paper was impregnated with a solution which contained 2.5 g of copper bromide and 1 g of a 20 ⁰ Z ₀ IgCn isopropanol dispersion of colloidal graphite in 10 ecm of methanol. The paper was dried and a disk 19 mm in diameter was punched out of it. The silver sheets coated with the electrolyte and the copper bromide paper disk were then brought into tight contact with each other. The following terminal voltages were achieved with an external resistance of

οοΩ 10 "> Ω 10 ⁹ Ω 10 ⁸ Ω 10'Ω 10 ^β Ω 0.76 ν 0.76 ν 0.76 ν 0.76 ν 0.74 ν 0.64 ρ

3. The solid electrolyte was made by melting silver bromide at 0.00, 0.01, 0.1, 1.0, 3.0, 5.0, 7.0 and 3.0

1.85

1.6

2.0

3.05

1.05

0.2

0.1

0.2

1.5

6th
2
2

up to 2
23

10.0% tellurium produced. These various electrolytes were then rubbed onto 0.125 mm thick silver sheets which had previously been treated with a 35% strength nitric acid solution, washed with pure water and then burned over a flame. The electrolyte was 0.050 to 0.075 mm thick. The positive electrodes were 5 / _o prepared aqueous graphite dispersion by impregnating filter paper with a °, the somewhat nonionizing wetting agent was added.

After drying this paper was further impregnated with a 25 ° / ₀ solution of copper bromide in methanol. Then the paper was dried again and cut into slices. These disks were then placed on the electrolyte-coated side of the silver sheet and a copper disk 25.4 mm in diameter was placed on the other side of the paper. The disks were held in tight contact with one another. The elements thus formed showed the electrical properties shown below.

electrolyte

s Clamping voltage (volts) at a r 1Ο ⁸ Ω 10'Ω ι 10 ⁶ Ω Inner Current with the same exterior external resistance of 0.80 0.80 0.73 resistance and inner resistance. οοΩ 10 ⁹ Ω 0.80 0.75 0.49 10 ³ Ω Microamps 0.80 0.80 0.79 0.76 0.57 114 3 0.80 0.80 0.77 0.74 0.60 599 1 0.80 0.80 0.80 0.79 0.71 323 1 to 2 0.80 0.79 0.80 0.79 0.78 178 2 0.80 0.80 0.72 0.72 0.69 70 4th 0.80 0.80 0.71 0.71 0.68 18th 16 0.73 0.73 24 11 0.71 + 0.71 31 8th

AgBr, pure

AgBr +0.01 ⁰ Z ₀ Te

AgBr +0.1 ⁰ Z ₀ Te

AgBr + 1 ⁰ Z ₀ Te

AgBr + 3 ⁰ Z ₀ Te

AgBr + 5 ⁰ Z ₀ Te

AgBr + 7% Te

AgBr + 10 ⁰ Z ₀ Te

The internal resistance was measured by decreasing half, in this case the external one external load was changed until the emf on the 70 resistance equals the internal resistance. With long

Continuous exposure to air did not reveal any significant change in the electrical properties. After 31 days of storage in air, an element with an electrolyte with 5 percent by weight tellurium showed an EMF of 0.74 volts, an internal resistance of 1.8 · 10 ³ Ω and a current of 80 microamps with the same internal and external resistance.

An examination of the teniperature dependency of this Elements were made at 50, 29 and about -75 ° C. The results show that the elements have favorable characteristics over this temperature range as shown in the table below emerges.

electrolyte temperature EMK
volt Inner
resistance
10 ³ Ω Current at the same
internal and external
resistance
Microamps Short circuit current
Microamps AgBr, pure
AgBr + 5% Te 50 ° C
29 ⁰ C
about -75 ° C
50 ° C
29 ° C
about -75 ° C 0.79
0.77
0.74 ⁵
0.76
0.74
0.54 13th
65
> 2.10 ³
1.5
1.8
600 24
5
200
80
* 50 to 60
8th
<1
600
200
1

*) Not measurable.

Elements with silver bromide and tellurium as electrolytes are preferable to those described above because the Silver bromide is more conductive than chloride. It has a higher electromotive force, and the copper bromide is less hygroscopic than the chloride.

Silver iodide can also be used, which is generally a better ionic conductor than bromide but it is less useful than that in most cases because of its volatility Bromide or chloride. Other electrolytes in solid state that are beneficial by the addition of tellurium The halogens of mercury, antimony, bismuth and lead can be modified.

It should also be noted that the composition of the electrodes differ from what has been described can. As will be apparent to those skilled in the art, metals such as strontium, barium, rubidium and others, can be used as negative electrodes, and there can be gaseous elements in surface layers of Solid material are absorbed, as well as oxidizing salts are used as positive electrodes.

Claims (4)

Patent claims: 1. Galvanic primary element with negative silver electrode and solid, water-free electrolyte Metal halides, characterized in that the electrolyte contains tellurium. 2. Element according to claim 1, characterized in that the electrolyte is 3 to 10 percent by weight Contains tellurium. 3. Element according to claim 1, characterized in that the electrolyte consists of a mixture of Silver bromide with 3 to 10 percent by weight tellurium, the negative electrode made of silver and the positive Electrode is made of copper bromide. 4. A method for producing the electrolyte according to claim 1, characterized in that the tellurium is fused with the electrolyte. References considered: U.S. Patent Nos. 2,689,876, 2,690,465. © 809 637/125 9.