US2290998A - Electrolytic cell comprising filmforming electrodes - Google Patents
Electrolytic cell comprising filmforming electrodes Download PDFInfo
- Publication number
- US2290998A US2290998A US650912A US65091233A US2290998A US 2290998 A US2290998 A US 2290998A US 650912 A US650912 A US 650912A US 65091233 A US65091233 A US 65091233A US 2290998 A US2290998 A US 2290998A
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- US
- United States
- Prior art keywords
- film
- electrolyte
- condenser
- aluminum
- condensers
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- 239000003792 electrolyte Substances 0.000 description 28
- 229910052782 aluminium Inorganic materials 0.000 description 14
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 13
- 235000010210 aluminium Nutrition 0.000 description 13
- 238000004090 dissolution Methods 0.000 description 9
- 239000002253 acid Substances 0.000 description 7
- 239000000126 substance Substances 0.000 description 7
- 230000015556 catabolic process Effects 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 239000002244 precipitate Substances 0.000 description 6
- 229920006395 saturated elastomer Polymers 0.000 description 6
- 238000000034 method Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 150000002739 metals Chemical class 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- MXRIRQGCELJRSN-UHFFFAOYSA-N O.O.O.[Al] Chemical compound O.O.O.[Al] MXRIRQGCELJRSN-UHFFFAOYSA-N 0.000 description 3
- 229940024548 aluminum oxide Drugs 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910021538 borax Inorganic materials 0.000 description 2
- 229910052593 corundum Inorganic materials 0.000 description 2
- 239000010431 corundum Substances 0.000 description 2
- 239000012213 gelatinous substance Substances 0.000 description 2
- 230000008439 repair process Effects 0.000 description 2
- 239000010979 ruby Substances 0.000 description 2
- 229910001750 ruby Inorganic materials 0.000 description 2
- 239000004328 sodium tetraborate Substances 0.000 description 2
- 235000010339 sodium tetraborate Nutrition 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- SCVJRXQHFJXZFZ-KVQBGUIXSA-N 2-amino-9-[(2r,4s,5r)-4-hydroxy-5-(hydroxymethyl)oxolan-2-yl]-3h-purine-6-thione Chemical compound C1=2NC(N)=NC(=S)C=2N=CN1[C@H]1C[C@H](O)[C@@H](CO)O1 SCVJRXQHFJXZFZ-KVQBGUIXSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- -1 for instance Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000009738 saturating Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/004—Details
- H01G9/022—Electrolytes; Absorbents
Definitions
- Such metals for instance, aluminum, when constituting the positive electrode of a cell having a suitable aqueous electrolyte, do not dissolve in the the electrolyte upon passage of the current as do most of the metals, but instead become covered with a hard film.
- This film oifers a high resistance to the fiow of current as long as the aluminum is the anode. However, if the aluminum is made the cathode, the film offers practically no resistance to the passage of the current. 4
- Electrolytic cells of the above type are widely used as electrolytic condensers, rectifiers and lighting arresters.
- Such electrolytic cells as stated comprise an aluminum anode, a suitable aqueous electrolyte;- for instance, a solution of borax and boric acidand the film is formed by subjecting the cell to gradually increasing electrical potentials, whereby the current fiow is properly regulated; the
- the periods of idleness are long compared with the periods of operation.
- the amplitude of the current will be determined by the total resistance of the circuit, which in addition to the condenser, also comprises other devices. These devices may be damaged by the excessive surge of the condenser, unless their resistance is made high enough to .prevent such. However, to provide these devices with suificient resistance is not always practicable, and even if feasible will require the use of devices of higher resistance than would be desirable for best operating characteristics of the circuit.
- condensers deteriorate during idleness due to the dissolution of the film in the electrolyte, which is evidenced by a decrease in breakdown voltage and an increase in leakage current.
- present day condensers having a breakdown voltage of 450 volts after their formation when left idle for a few days, show a breakdown voltage of about 425 volts only.
- dissolution of the film and reduction in breakdown voltage is correspondingly greater.
- the object of my present invention is therefore to prevent dissolution of the film while the condenser is out of operation and thus to obtain con-
- the condenser is sub-v jected to variations of the ambient temperature and to temperature rises during its operation.
- the solubility of the film in the electrolyte is as a rule greater at the higher temperatures than at'the lower temperatures, with the result that the electrolyte which is saturated at a lower temperature and therefore would not attack the film,
- Aluminum oxide and hydroxide exists in various forms of different solubility. For instance, in some forms, as ruby or corundum, aluminum hydroxide is very slow to dissolve in any solvent; on the other hand, in the form of hydrousgelatinous precipitates, it dissolves very rapidly in any good solvent. The partially hydrated aluminum oxide constituting the film, while more speedily soluble than ruby or corundum, has a much'lower rate of solubility than the gelatinous aluminum hydroxide.
- I may add to the electrolyte, a solution containing aluminum which when added will cause an excess of this gelatinous precipitate to be thIO'JIl down.
- the container it forms one-of the electrodes of the condenser, and may be of filming or nonfilming metal.
- the electrolyte it consists of a solution of a weak acid and a salt of a weal: acid, for instance, of an aqueous solution of borax and boric acid.
- A. second electrode is of film-forming metal
- the film on the electrode is preferably formed in an electrolyte to which is added a substance which is partly soluble in the electrolyte, and which prevents dissolution of the film, for instance, a substance which has the same constituency as the film.
- the electrolyte is preferably saturated with this substance and preferably an excess of solid of the substance being provided.
- the forming electrolyte is preferably alternately heated and cooled duringthe forming process.
- the electrolyte N5 of the condenser comprises a substance which is at least partly soluble in the electrolyte and which prevents dissolution of the film of the filmed electrode, such substance being for instance, of the same constituency as the film, and preferably more soluble than the film, for instance, a hydrous gelatinous precipitate of aluminum oxide with which the electrolyte is preferably saturated with an excess of the precipitate being also present in the electrolyte.
- the container I0 is closed by a cover I 2 of insulating material through which projects a threaded extension I! of the electrode l3, said extension being provided with nuts l5-l5 to form one of the outside terminals of the condenser, the container I0 forming-the other terminal thereof.
- the cover 12 is provided with a vent I 8, and a peripheral gasket I9, around which the free end of the container Ill is crimped.
- sealing means are also provided between the protruding end of the electrode l3 and the cover l2.
- An electrolyte for an electrolytic condenser having a filmed aluminum electrode comprising an acid and a salt and a hydrous gelatinous compound of aluminum and oxygen.
- electrolyte for an electrolytic device having an alumium electrode provided with a film containing a partially hydrated aluminum oxide comprising prior to use, a weak acid and the salt of a weak acid and a gelatinous compound of aluminum and oxygen.
- An electrolyte for an electrolytic device having an electrode provided with an oxygenated film of aluminum comprising prior to use, a weak acid and the salt of a weak acid, and a substance soluble in the electrolyte more readily than said film, and comprising a gelatinous compound of 5 oxygen and aluminum.
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Description
2,290,998 ELECTROLYTIC CELL COMPRISING FILM-FORMINGELECTRODES July 28, 1942. I P. ROBINSON Original Filed July 16, 1930 Pasfon Pobu'a-Son;
attorneg Patented July 28,
UNITED STATES PATENT OFFICE ELECTROLYTIC CEIiL COMPRISING FILM- FORMING ELECTRODES Preston Robinson, North Adams, Mass., assignor to Sprague Specialties Company, North Adams, Mass., a corporation of Massachusetts Original application July 16, 1930, Serial No. 468,466. Divided and this application January 9, 1933, Serial No. 650,912.
3 Claims.
tain metals. Such metals, for instance, aluminum, when constituting the positive electrode of a cell having a suitable aqueous electrolyte, do not dissolve in the the electrolyte upon passage of the current as do most of the metals, but instead become covered with a hard film. This film oifers a high resistance to the fiow of current as long as the aluminum is the anode. However, if the aluminum is made the cathode, the film offers practically no resistance to the passage of the current. 4
Electrolytic cells of the above type are widely used as electrolytic condensers, rectifiers and lighting arresters.
Such electrolytic cells as stated comprise an aluminum anode, a suitable aqueous electrolyte;- for instance, a solution of borax and boric acidand the film is formed by subjecting the cell to gradually increasing electrical potentials, whereby the current fiow is properly regulated; the
film which consists of a partially hydrated alumi num oxide is thereby gradually formed on the surface of the aluminum, all this being well known to the art. I
When using such cells as static condensers, it is relied upon that the film once properly formed will remain unchanged and. retain its high resistance to voltages of proper polarity as long as their values do not exceed the maximum forming voltage.
This is true to a great extent when the condenser is in continuous operation under the proper voltage conditions, as in such case the film does not dissolve in the electrolyte. However, when the condenser is idle, a slow dissolution of the film in the electrolyte takes place, which is highl objectionable.
For instance, when electrolytic condensers are used in filter circuits of radio receiving sets, the periods of idleness are long compared with the periods of operation.
When after a period of idleness the condenser- In Canada June 29,
is again placed in operation, a current surge takes place due to two causes. One cause isthe loss of charge of the condenser due to leakage; this also takes place with other types of condensers, as for instance, paper impregnated condensers. However, the surge due to this cause being a transient current of very short duration, can be disregarded as a rule.
7 The second cause for a current surge is specific with electrolytic condensers and is due to the above referred to dissolution of the film. When such condensers, after a prolonged idleness are placed again in operation, the film, having been partly dissolved, offers a reduced resistance to the current flow. While this current flow gradually rebuilds the dissolved film, such rebuilding requires considerable time and if not otherwise checked, a relatively large current flow will persist for a considerable time.
The amplitude of the current will be determined by the total resistance of the circuit, which in addition to the condenser, also comprises other devices. These devices may be damaged by the excessive surge of the condenser, unless their resistance is made high enough to .prevent such. However, to provide these devices with suificient resistance is not always practicable, and even if feasible will require the use of devices of higher resistance than would be desirable for best operating characteristics of the circuit.
Not only is this current surge highly objectionable, but the repair of the film due to'sthe sudden application of the full operating voltage will be only partial, as complete repair would require a gradual slow raising of the voltage, similar to the initial forming process. In fact, after longer periods of idleness, the initial quality of the film could be only restored by repeated formation.
Thus, besides causing an objectionable surge the condensers deteriorate during idleness due to the dissolution of the film in the electrolyte, which is evidenced by a decrease in breakdown voltage and an increase in leakage current. For instance, present day condensers having a breakdown voltage of 450 volts after their formation, when left idle for a few days, show a breakdown voltage of about 425 volts only. Thus roughly stated in a few days 25 volts of film is dissolved in the electrolyte, For longer periods of idleness, dissolution of the film and reduction in breakdown voltage is correspondingly greater.
Thus the slow dissolution of the film in periods of idleness of the condenser has three drawbacks, namely, excessive current surge, lowering of breakdown voltage, and increasing of leakage current.
The object of my present invention is therefore to prevent dissolution of the film while the condenser is out of operation and thus to obtain con- However, in practice, the condenser is sub-v jected to variations of the ambient temperature and to temperature rises during its operation. The solubility of the film in the electrolyte is as a rule greater at the higher temperatures than at'the lower temperatures, with the result that the electrolyte which is saturated at a lower temperature and therefore would not attack the film,
at a higher temperature becomes unsaturated and will become saturated partly by dissolving the added solid, but partly also by dissolving the film.
By providing an excess of solid as stated and so forming the film that the electrolyte is alternately heated and cooled during the forming process, I have been able partially to take care of this objection,
However, by a further improvement, explained hereafter, I have been able to prevent altogether dissolution of the film in the electrolyte, irrespective of the duration of idleness of the condenser,
and irrespective of temperature changes during,
either operation or idleness.
Aluminum oxide and hydroxide exists in various forms of different solubility. For instance, in some forms, as ruby or corundum, aluminum hydroxide is very slow to dissolve in any solvent; on the other hand, in the form of hydrousgelatinous precipitates, it dissolves very rapidly in any good solvent. The partially hydrated aluminum oxide constituting the film, while more speedily soluble than ruby or corundum, has a much'lower rate of solubility than the gelatinous aluminum hydroxide.
By adding such gelatinous substance to the electrolyte and saturating it at a low temperature, it will remain saturated when the temperature is raised, whereby the excess aluminumoxide for saturation will be supplied by the gelatinous substance only and the film will not be attacked. In practice, I add the hydrous-gelatinous precipitate to the electrolyte, prior to the assembly of the condenser.
Or I may add to the electrolyte, a solution containing aluminum which when added will cause an excess of this gelatinous precipitate to be thIO'JIl down.
The advantage of my invention manifests itself during the original forming process of the condensers, and condensers having a pre-saturated electrolyte and provided with an excess of gelatinous precipitates show a film of greater uniformity than electrolytic condensers manufac- The most important advantage of my process,
however, is that with condensers manufactured in accordance therewith, after any period of idleness which may occur in practice, the current surge is almost negligible and the condensers retain their initial breakdown voltage and insulating resistance.
In the drawing forming part of this specification, the single figure is a partly sectionized side view of an electrolytic condenser embodying my invention.
The container it forms one-of the electrodes of the condenser, and may be of filming or nonfilming metal. The electrolyte it consists of a solution of a weak acid and a salt of a weal: acid, for instance, of an aqueous solution of borax and boric acid.
A. second electrode is of film-forming metal,
for instance, of aluminum, projects into the con- The film on the electrode is preferably formed in an electrolyte to which is added a substance which is partly soluble in the electrolyte, and which prevents dissolution of the film, for instance, a substance which has the same constituency as the film. The electrolyte is preferably saturated with this substance and preferably an excess of solid of the substance being provided. The forming electrolyte is preferably alternately heated and cooled duringthe forming process.
The electrolyte N5 of the condenser comprises a substance which is at least partly soluble in the electrolyte and which prevents dissolution of the film of the filmed electrode, such substance being for instance, of the same constituency as the film, and preferably more soluble than the film, for instance, a hydrous gelatinous precipitate of aluminum oxide with which the electrolyte is preferably saturated with an excess of the precipitate being also present in the electrolyte.
The container I0 is closed by a cover I 2 of insulating material through which projects a threaded extension I! of the electrode l3, said extension being provided with nuts l5-l5 to form one of the outside terminals of the condenser, the container I0 forming-the other terminal thereof. v
The cover 12 is provided with a vent I 8, and a peripheral gasket I9, around which the free end of the container Ill is crimped. Preferably sealing means (not shown) are also provided between the protruding end of the electrode l3 and the cover l2.
While I have described my invention in its application to electrolytic condensers, I do not wish .to be limited to such application, as my invention is equally well applicable to other electrolytic devices with film-forming electrodes;-
and while I have assumed aluminum as the material for the film-forming electrodes, other filmforming metals, for instance, tantalum, molybdenum, etc., may be substituted. Therefore I do not wish to be limited to the illustrated example of my application, but wish the appended claims to be construed as broad as permissible in view of the prior art.
What I therefore claim and desire to secure by Letters Patent is:
1. An electrolyte for an electrolytic condenser having a filmed aluminum electrode, comprising an acid and a salt and a hydrous gelatinous compound of aluminum and oxygen.
2. electrolyte for an electrolytic device having an alumium electrode provided with a film containing a partially hydrated aluminum oxide, comprising prior to use, a weak acid and the salt of a weak acid and a gelatinous compound of aluminum and oxygen.
3. An electrolyte for an electrolytic device having an electrode provided with an oxygenated film of aluminum comprising prior to use, a weak acid and the salt of a weak acid, and a substance soluble in the electrolyte more readily than said film, and comprising a gelatinous compound of 5 oxygen and aluminum.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US650912A US2290998A (en) | 1930-07-16 | 1933-01-09 | Electrolytic cell comprising filmforming electrodes |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US468466A US2290996A (en) | 1930-07-16 | 1930-07-16 | Art of electrolytic cells comprising film-forming electrodes |
US650912A US2290998A (en) | 1930-07-16 | 1933-01-09 | Electrolytic cell comprising filmforming electrodes |
Publications (1)
Publication Number | Publication Date |
---|---|
US2290998A true US2290998A (en) | 1942-07-28 |
Family
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US650912A Expired - Lifetime US2290998A (en) | 1930-07-16 | 1933-01-09 | Electrolytic cell comprising filmforming electrodes |
Country Status (1)
Country | Link |
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US (1) | US2290998A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2977514A (en) * | 1961-03-28 | Electrolytic device with gel electro- |
-
1933
- 1933-01-09 US US650912A patent/US2290998A/en not_active Expired - Lifetime
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2977514A (en) * | 1961-03-28 | Electrolytic device with gel electro- |
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