DE1639275B2 - Electrolyte for electrolytic capacitors - Google Patents

Description

a spec. Resistance of 275 Ω · cm at 50 ⁰ C on. The maximum voltage of this electrolyte is 140VoIt.

Example 3

11.7 parts of D (-> lactic acid, 3 parts of diethylamine, 1 part concentrated ammonia are dissolved in 84.3 parts of ethylene glycol at 130 ° C, the electrolyte solution exhibits a resistivity of 310 Ω · cm at 50 ⁰ C. The maximum voltage. is 115 volts.

Example 4

10 parts sec. Ammoniumcitrai, 1 part of bis (tert-butylammonium> citrate are dissolved in 89 parts of ethylene glycol at 170 ⁰ C. The thin liquid dark green colored solution has a specific resistance of 235 Ω-cm at 50 ⁰ C. The maximum voltage of this electrolyte is included. 125 volts.

There is a possibility that the electrolyte prepared for the impregnation by the temperature treatment undergoes chemical changes when dissolving. For example, citric acid can contribute

at elevated temperature by splitting off water in ice or trans-aconitic acid.

Some typical data about the behavior of capacitors that are used with the 5 electrolytes mentioned above were impregnated.

For comparison, aluminum wound capacitors of 22 μΡ / 25 V, 200 μΡ / 50 V and 15 μΡ / 80 V were used with an electrolyte made from boric acid, ethylene glycol, ammonia and water and with an electrolyte

ίο manufactured according to the invention and tested ^{under nominal voltage at 100 0 C.}

The pre-acidic capacitors already fell after 1 to 2 days due to a very strong increase in Residual streams from, whereby the closures were pushed out by the evolution of gas. Were against it the capacitors impregnated with the electrolyte according to the invention after 500 hours, and Although otherwise under the same conditions as the boric acid-containing capacitors, hardly changed.

ao The specific resistance of the electrolyte according to the invention is also with regard to its temperature behavior more advantageous, as the table below shows.

•cm) T ⁰ C -40 -25 0 25th 50 75 -50 123'0OO 27'200 2Ί60 616 264 160 "Boric acid" •cm) immeasurable Electrolyte δ (Ω 54'00O 12Ί00 1,660 563 246 132 "News" 195Ό00 Electrolyte δ (Ω

A similar advantageous behavior is shown by the electrical values with an electrolyte according to FIG of the invention impregnated capacitors as a function of temperature.

Claims (5)

1 2 Water and patent claims deviating from an optimum: pH values of the electrolyte solution corrosive to metals, especially aluminum. 1. Electrolyte for electrolytic capacitors, ent- The disadvantages described can be caused by a holding at least one aliphatic hydroxy 5 electrolyte avoided, the largely water carboxylic acid, one glycol and at least one ali- is free. One such electrolyte, which is an aliphatic phatic amine, characterized thereby- hydroxycarboxylic acid, glycol and an aliphatic net that the aliphatic hydroxycarboxylic acid contains amine is known from FR-PS 1462070, is at least partially present as the ammonium salt. In this known electrolyte, however, the 2. Electrolyte according to claim 1, characterized marked io hydroxycarboxylic acid recorded completely with the glycol, that the aliphatic hydroxycarboxylic acid esters, so that practically no acid ions in the electro-tartaric acid, Pyruvic acid, citric acid, lytes are present. Such an electrolyte therefore has, ins-lactic acid, " Gluconic acid, aconitic acid or a special one at running temperatures, a bad one Mixture of these acids is. Conductivity, which is detrimental to the electrical 3. Electrolyte according to claim 1 or 2, characterized in that 15 properties of the capacitor have an effect,
characterized in that the aliphatic hydroxy object of the invention is to provide an electrolyte for carboxylic acid in a proportion of 1 to 20 weight electrolytic capacitors, which is not present as a percentage. partial influencing of the oxide film and, in particular 4. Electrolyte according to one or more of the special features at low temperatures, a good motto 1 to 3, characterized in that the 20 has the ability. cation-forming components in a proportion This task is carried out with an electrolyte of the from 1 to 15 percent by weight. type mentioned above solved by the fact that the ali- 5. Electrolyte according to one or more of the phatic hydroxycarboxylic acid at least partially Claims 1 to 4, characterized in that the ammonium salt is present. at least one aliphatic amine is present, 25 This electrolyte is largely anhydrous; with that has hydroxyl groups in the molecule. Water shows diluted solution, depending on the concentration of the constituents, a neutral or weakly acidic reaction. The invention is based on the finding that 30 ammonium salts of aliphatic mono- or polybasic carboxylic acids, which also contain one or more hydroxyl The invention relates to an electrolyte having groups in the carbon chain, in particular For electrolytic capacitors, containing at least those ammonium salts, which are essentially Meneine aliphatic hydroxycarboxylic acid, a glycol and gene soluble in the electrolytes of the capacitors at least one aliphatic amine. 35 are able to conduct electricity well, on aluminum It is a characteristic property of aluminum and has an oxidizing effect even after prolonged use minium-EIektrolytkapensatoren that when they are increased only minor changes in the oxide film Temperature during operation, even more at cause. stress-free storage, leads to an increase in electrolyte solutions consisting of an ammonium salt Capacity and residual current tend. This appearance of tartaric acid, lactic acid, citric acid, and glucose is attributed to the corrosion of the aluminum acid, pyruvic acid or their mixtures. The reasons for this are not yet available in all and where a glycol is used as a solvent Details are known and are complex in nature. is used, show even at moderate concentrations it is known that different ions act with low specific resistances but the chlorine, sulphate and nitrate ions make the 45 corrosive. On the other hand, you can only achieve - albeit in traces - always in the finished organic amines of the acids mentioned above in Condensers are present, the life of which glycols as solvents shorten the desired conductors. Furthermore, the pre-ability values in the electrolyte do not play a role, so that the electrical loss is present The amount of water and the pH value of the capacitor's electrical factor is adversely affected, lyt solution plays a very important role. 50 By combining both electrolytes one achieves Such electrolytic capacitors are made from, however, the desired conductivity values with very one pair of electrodes, one of which has a greatly reduced corrosive effect.
at least one is made of a metal on which the following are examples of the electrolyte Surface carries a dielectric oxide film. This specified according to the invention.
Oxide film can be formed anodically, by air oxidation 55 B '' 1 1 or on any other chemical or physical ^p ic ways are applied and is available on its 15 parts D (+) - tartaric acid, 3 parts monoethanol surface in contact with an electrolyte. amine, 2 parts of diammonium tartrate are in 80 parts The capacitance and leakage current increase is related to ethylene glycol dissolved at 175 ⁰ C. The result is a thin, progressive change in the oxide film 60, a liquid, slightly yellowish-colored solution that combines during operation. The oxide resistivity of 510 Ω · cm at 50 ^° C. originally shows an equal film with aluminum electrodes.
Layer. While using the capacitor example 2 dull spots appear in places. Similar er- 65 Symptoms also occur with electrodes made of another 15 parts bis (tert-butylammonium) tartrate, 4 parts oxide film-forming metals such as tantalum and niobium. sec. Ammonium citrate are at 130 ⁰ C in 81 parts As already mentioned, certain ions, ethylene glycol, have a dissolved effect. The liquid solution has