DE1914420C3 - Electrolytic capacitor - Google Patents

Description

To create solvents that have improved electrical properties, in particular a lower loss

The invention relates to an electrolyte cone angle.

capacitor with two electrodes made of aluminum, tantalum This task is performed with an electrolyte capacitor

or niobium or their alloys, of which at least 20% of the solvent of the type mentioned is dissolved in that it is provided with a dielectric layer, the solvent is at least 20% 3-hydroxy and one that is in contact with the electrodes > consists of propionitrile and / or 2-methyllactonitrile,
existing anhydrous electrolytes, which are in a mini- This will have adverse effects on the

At least a hydroxynitrile-containing solvent oxide film is avoided, resulting in lower losses contains ionogenic substance. angle is achieved that even during operation

It is a particularly characteristic property that is still decreasing.

of aluminum electrolytic capacitors, so that they can be used as ionogenic substances, the salts of Borrend of the operation, even more with de-energized acid, oxycarboxylic acids, picric acid etc. with ammo storage, at elevated temperature to an increase niak, alkyl or aryl amines are used, the the capacity and the residual current. These er- in substantial quantities in the mentioned solution-notes will mediate on the corrosion of the aluminum are soluble, conduct the electrical current well, returned. The causes are at the current level 50 and have an oxidizing effect on so-called valve metals of the findings not yet known in full detail, in contrast to the aqueous boric acid and glycol and are complex in nature. Different containing electrolytes even with prolonged use existing ions, especially the chloride, sulphate, greatly reduced changes in the oxide film - nitrate, Iron and copper ions, shorten the call.

Lifetime of the capacitors and are - if 55 As already mentioned, certain ions act, even in traces - always in the finished condensate water and pH-adjusters deviating from an optimum present. Furthermore, the values of the solution in the electrolyte are particularly corrosive to metals The amount of water present and the pH of the aluminum. On the other hand, those with electrolyte con-electrolyte solution a very important role. Electrolytes used further capacitors according to the invention the electrical properties, in particular, are largely water-free; they show depending on the group special the temperature characteristics, the electration of the components a neutral or weak one Lytcapacitors used largely from the elec- tric acid reaction. The above disadvantages will be trolytes determined. therefore largely through the use of these elec-

Such electrolytic capacitors are avoided from trolyte. A particular advantage of a pair is also manufactured electrodes, one of which minde- 65 that the electrolytes ge of electrolytic capacitors - .. £ (as one consisting of a metal which carries on its measure of the invention for an extended working Tempe surface a dielectric Qxidfilm This temperature range of the capacitors can be used and oxide film can be formed anodically, by air oxidation, that their electrical properties are in "this"

10

Hardly change the temperature range. In contrast to aqueous boric acid and glycol containing capacitors the loss factors at increased temperatures -. * temperatures as a function of time are significantly better.

The following are examples of the electrolyte !? the Elektrolytkondensatpren specified according to the invention.

example 1

5 parts of orthoboric acid in 95 parts of 3-hydroxypropionitrile dissolved and 1.5 parts of triethanolamine added with stirring. The result is a thin fluid clear solution that has a resistivity of 1200 ohm · cm at 50 ° C. The maximum tension this electrolyte is 510 volts.

Example 2

7 parts of orthoboric acid in 93 parts of 3-hydroxypropionitrile dissolved and added 3.5 parts of triethanolamine with stirring. The obtained electrolyte solution has a specific resistance of 837 ohm · cm at 50 ° C. The maximum voltage is 370 volts.

Example 3

10 parts of orthoboric acid are dissolved in 90 parts of 3-hydroxypropionitrile and 2.5 parts of diethylamine are added with stirring. The specific resistance of the electrolyte at 50 ^° C. is 252 ohm · cm, the maximum voltage 160 volts.

30 Example 4

7 parts of ammonium picrate are dissolved in 50 parts of ethylene glycol and 50 parts of 3-hydroxypropionitrile. The resistivity of the solution is 210 Ohm - cm at 50 ⁰ C. remains liquid to -6O ⁰ C. The solution.

Example 5

10 parts of picric acid and 6.3 parts of triethanolamine are dissolved in 100 parts of 3-hydroxypropionitrile. The specific resistance is 210 ohm · cm at 50 ⁰ C, the maximum voltage is 180 volts.

Example 6

10 parts of picric acid and 4.6 parts of diethanolamine are dissolved in 100 parts of 3-hydroxypropionitrile with 20 parts of butyloxyethanol. The electrolyte solution obtained has a specific resistance of 230 ohm cm at 50 ^° C.

Example 7

9.6 parts of D (-) lactic acid, 3.4 parts of diethylamine are dissolved in 50 parts of α-hydroxyisobutyronitrile and 50 parts of 3-hydroxypropionitrile. The specific resistance of the solution is 270 ohm cm at 50 ^° C.

Some typical data about the behavior of the capacitors which have been impregnated with the above-mentioned electrolytes are listed below
For comparison, aluminum wound condenser

capacitors of 100 μΡ and 15 V with one listed above Electrolytes are impregnated, then formed and then examined in a temperature endurance test. The same type of capacitor was made with aqueous, glycolic and boric acid containing electrolytes

and treated as above. The ambient temperature in the life test was +85 ⁰ C. Table 1 shows the electrical properties of the known electrolytic capacitor in dependence on the duration of the test, while Table 2, the electrical values of the after

»5 invention made capacitor also in Depending on the duration of the test.

Table 1

Test duration
(Hours.) C. tg <5
(%) I «
(μΑ) Impedance
at 20 kHz
(Ohm) O
200
Table 2 117
145 6.0
10.0 2.0
2.92 0.35
0.68 Test duration
(Hours.) C.
^ F) tgi5
(%) Ir
(μΑ) Impedance
at 20 kHZ
(Ohm)

200

500

1000

1500

109
107
106
108
106

6.4
5.2
5.8
5.3
5.8

1.90 1.63 1.45 1.20 0.80

0.26 0.27 0.31 0.22 0.25

Claims (4)

is made chemically or physically and is in contact with a conductive electrolyte on its surface. 1. Electrolytic capacitor with two electrodes The increase in capacity * and residual current is related of aluminum, tantalum or niobium or their S a progressive change in the oxide film Alloys, at least one of which is combined with one during sleep. For example, represents dielectric layer is provided and with an origin with the aluminum electrodes of the oxide film the electrodes in contact with water lent a uniform, weak interference colors free electrolyte present in at least one layer. While using the Hydroxynitrile-containing solvents of an io capacitor form matt spots in places, ionogenic. Contains substance, which means that similar phenomena also occur with electrodes denotes that the solvent ipin is made of other metals that form an oxide film, such as at least 20% of 3-hydroxypropionitrile and / tantalum and niobium. or 2-methyllactonitrile. The invention is based on the knowledge that 2. Electrolytic capacitor according to claim 1, 15 such disadvantageous changes are only avoided by the fact that the solvent can be used if an electrolyte veraußerdem an alcohol, ether alcohol or one that is completely anhydrous or only ge-nitrile of aliphatic carboxylic acids or Garring contains quantities of water (less than 1 ^),
contains acid amides. As a solvent for such anhydrous electrical 3. Electrolytic capacitor according to claim Ioder2, ao lyte are, for example, hydroxynitriles, like this characterized in that the electrolyte is known as from US-PS 21 52 465. From the numberionogenic Substance boric acid, aliphatic dicar-rich substances that fall under this term, bonsäure, picric acid, aliphatic hydroxycar- there are only ethylene cyanohydrin, ethylidenecyanohydric acid, called orthophosphoric acid or its midrin and acetone cyanohydrin. The losses contains. as angle of capacitors made with these nitriles 4. Electrolytic capacitor manufactured according to one of the following, however, is average Proverbs 1 to 3, characterized in that the 9.9%. Electrolyte ammonia, aliphatic and / or In US-PS 29 45 164 it is even pointed out aromatic amine, aliphatic hydroxyl group- that hydroxynitrile is used for electrolytes from electrolyte pen Contains amine or mixtures thereof. 30 capacitors are not suitable. The object of the present invention is to provide an electrolytic capacitor with a substantially anhydrous electrolyte with a hydroxynitrile as