US2375211A

US2375211A - Electrode and method of making same

Info

Publication number: US2375211A
Application number: US227316A
Authority: US
Inventors: Brennan Joseph Barry
Original assignee: Individual
Current assignee: Individual
Priority date: 1937-08-09
Filing date: 1938-08-29
Publication date: 1945-05-08
Anticipated expiration: 1962-05-08

Description

y 8; 1945. J. B. BRENNAN 2,375,211

ELECTRODE AND METHODS OF MAKING SAME Filed Aug. 29, 1938 2 Sheets-Sheet l IIIIIIIIm llluflll im Egg: 5 I, 0

1 N VENT OR JOSEPH B- .F/PE/V/VA IV ATTORNEYS y 3, 1945- J. B. BRENNAN 2,375,211

ELECTRODE AND METHODS OF MAKING SAME Filed Aug. 29, 1938 2 Sheets-Sheet 2 INVENTOR.

BY JOsEPHBBEEA/MN 74 r Y 21.13 m? fi m ATTORNEYS Patented May 8, 1945 OFFICE 2,375,211 ELECTRODE AND METHOD OF MAKING SAME Joseph Barry Brennan, Euclid, Ohio Application August 29, 1938, Serial No. 227,316

1 31 Claims.

This invention relates to electrodes or plates for various electrical devices such as condensers. rectifiers, lightning arrestors, batteries and the like and more particularly relates to electrodes or plates having active surfaces. of spray deposited material. This application i a continuation in part of my copending application Serial No. 158,105, filed August 9, 1937, now Patent No. 2,280,789, issued April 28, 1942. The invention will be described herein with particular reference to electrolytic condensers having electrode surfaces of spray deposited aluminum or other film forming metal, but it is to be understood that the invention is not limited to the particular embodiment described as it may be applied to various other electrical devices.

Electrodes or plates comprising finely divided, conductive, metallic particles deposited on a suitable base have, as noted in my aforesaid application and in my Patent No. 2,104,018 many advantages when incorporated in various electrical devices, particularly electrolytic condensers of the type embodying one or more electrodes provided with a dielectric film. These advantages principally flow from the fact that the effective area of the finely divided particles is very great as compared with the plane or directly measurable area of the base on which they are deposited. The present invention constitutes, in some respects, an improvement upon the inventions disclosed and claimed in my said patent and application and one of the objects of this invention is to provide a more eflicient electrode or plate of the type having a surface composed of minute conductive particles.

Another object is to provide such an electrode in which the conductivity of the spray-deposited layer is increased as compared to prior types of sprayed electrodes. Another object is to provide efficient and economical methods of making such electrodes. Another object is the provision of a condenser embodying such electrodes. A further object is the provision of a method of increasing the flexibility and strength of electrodes embodying or consisting of spray-deposited metallic layers. Another object is to provide an electrode or plate having a base of insulating or poorly conductive material and a conductive layer thereon having low resistance which will result in sub stantially uniform current density over its entire area when in use. A further object is to increase the adhesion of the spray deposited layer to the base. Another object is to provide a method of producing highly conductive paths in the sprayed surface of an electrode. A further object is to provide efficient and economical terminal constructions for electrodes having sprayed surfaces.

Further objects and advantages of my invention will become apparent from the following description of preferred forms thereof, reference being .made to the accompanying drawings. The essen- Figure 2 is a plan view of one of the electrodes shown in Figure 1; Figure 3 is a section on an enlarged scale taken along the line 3-3 of Fi ure 2; Figure 4 is a fragmentary illustration of an electrode generally similar to that shown in Figure 2. but embodying a slightly different terminal construction; Figure 5 is similar to Figure 4, but shows a further modification of the terminal construction; Figure 6 is a vertical section showing a wet type condenser embodying my invention; Figure 7 is a transverse section through the condenser shown in Figure 6 as indicated by the line 'l-i on Figure 6; Figure 8 is a plan view of one type of anode suitable for the condenser shown in Figure 6; Figure 9 is a view similar to Figure 8 but showing a modified type of electrode; Figure 10 illustrates a further modification; Figure 11 is a sectional view as indicated by the line il-H on Figure 10; Figure 12 illustrates another modified form of electrode; and Figure 13 is a section as indicated by the line i3-|3 on Figure 12.

As shown in Figure 1, a dry type of condenser made according to my invention may comprise two electrodes 10 separated by spacers H. The

electrodes may be provided with terminal tabs l4 and the whole assembly may be rolled into cylindrical form as indicated at It and impregnated with a suitable film maintaining electrolyte such as that disclosed and claimed in U. S. Patent No. 2,095,966. The spacers i2, which function to prevent electrical contact between the electrodes I0 and also retain the electrolyte in their interstices, are preferably formed of strips of paper or, as indicated in the drawings, of a woven material such as a fabric netting or glass cloth, the material preferably being coated with a suitable material which is insoluble in the electrolyte, as described and claimed in my application Serial No. 36,182,

filed August 14, 1935, now Patent No. 2,135,492,

issued November 8, 1938.

The electrodes ID are preferably constructed as shown in Figures 2 and 3 and consist of a base 20 of any suitable material, for example porous or woven material such as glass cloth, cotton netting, perforated paper, or wire screening. The

active surfaces 2| of the electrode are preferably for the electrodes.

denser is to beiput one or both of the electrodes may be provided with sprayed layers 2| of aluminum or other film forming metal the filmforming metal being formed with a dielectric film in any suitable manner known to those skilled in the art, for example by subjecting the electrode to electrolysis asan anode in 9. him forming bath such as a solution of borax and boric acid. If the condenser is intended for use in direct current service only one plate need be provided with a dielectric film, 'that plate con- 1 stituting the anode of the condenser. For such a direct current condenser the cathode may consist of aluminum or other fllm forming" metal or, if desired, a non-film forming metal such as copper may be used. If the condenser is intended for alternating current service both electrodes are preferably composed of sprayed film forming metalnnd both are provided with dielectric films.

Suchelectrodes, as pointed out in greater detail in my parent application No. 158,105 are very advantageous and condensers embodying my electrodes have extremely desirable characteristics largely because the electrodes have very great -capacities per unit of plane area andbecause condensers incorporating such electrodes have low resistance and power factor losses. I have discovered however, that the losses in the condenser can be further reduced and the characteristics of the electrodes and plates, and of condensers incorporating the same can be improved by providing the electrodes with one or more paths or areas having greater conductivity than the sprayed layers and extending from the region where the terminals are connected to the electrodes to regions remote from the terminals. Preferably I form such highly conductive paths by subjecting the spray deposited layers to heat to weld the sprayed particles in such paths or areas into a compact, substantially integral condition. This may be accomplished, for xample,by flame welding, as by an oxyacetylene torch, by heating the sprayed metal by an electric arc, or by electrical resistance methods such as a series of closely spaced spot welds or by passing the electrode between a pair of electrode rolls engaging opposite sides of the electrode and supplying the required welding current and pressure. In carrying out the welding operation by electrical methods, the apparatus employed should preferably be capable of accurate adjustment so that the current and time of application of the current can be controlled to produce a weld having the desired characteristics of high conductivity and mechanical strength. The electrodes employed should preferably be formed of materials which will not be deposited on the surfaces of the welded areas, electrodes of alloys of tungsten carbide and copper being suitable for this purpose. These matters are all within the knowledge of those skilled in the welding art.

The effect of such an operation is shown somewhat diagrammatically in the drawings, lines 22 indicating longitudinally extending conductive asgmu paths, while the

lines

22 and 24 indicate transversely extending conductive paths one of the lines 22 and the line 24 extending'adiacent to the terminal I of the electrode.

As is shown diagrammatically in Figure 3 the effect of the welding operation, particularly if the welding operation is accompanied by pressure as in the case of the electric resistance welding, is

to form the particles in the zone of the weld into a substantially integral mass as indicated for example at 25. When the operation is carried out on material deposited on a porous base, as shown in the drawings, the two opposite layers 2| are fused together through the interstices of the mautilized to its fullest extent further increasing the efllciency of the device in which the electrode is incorporated.

The conductive paths may be employed with any convenient type of terminal or tab construction, however, I have found an advantageous construction to consist of the metallic tab II which is secured to the sprayed layer 2| by a welding operation as indicated at 21 in Figure 3. As shown diagrammatically in Figure 3 this welding operation not only makes an excellent electrical connection and a secure mechanical Joint between the tab or terminal and the sprayed surface 2| but also the two sprayed surfaces on opposite sides of the base 20 are fused together as shown at 28 so that a low resistance connection is formed between the terminal and the layer 2|a on the side of the electrode opposite the terminal or tab l4. Even though only one side of the base is provided with a spray-deposited layer, the'terminal may be welded directly thereto.

A modified form of terminal construction is shown in Figure 4 in which the tab 20 consists of a small piece of the same material as the base 20 of the electrode having a sprayed coating on both sides, the sprayed coating on the tab being provided with a highly conductive path 3| produced as described above and the sprayed coatings on the tab and on the electrode itself being welded together to make the desired electrical and mechanical connection between the tab and the sprayed areas 2| of the electrode.

In Figure 5 I have illustrated a very economical type of terminal construction which may be employed with the condenser shown in Figure l or in various other types of condensers such as dry condensers embodying a plurality of flat plates or electrodes, alternate electrodes being of opposite polarity. In this modification of my invention the base 20 is provided with a sprayed layer 2| as before and includes the

conductive paths

22 and 24. However, in this form of my invention the terminal for connecting the electrode to an external circuit is formed merely by a sprayed area 32 extending from the main sprayed area 2| toward the edge of the base ma terial 20. The conductive path 24 is extended through this area as indicated at 33 and thus an eilicient electrical connection to the electrode can be made through the sprayed area 32. When such an electrode is employed in a paste type of condenser embodying a stack of electrodes of alternate polarity, the tabs or sprayed areas 32 may be disposed on opposite sides. of alternate electrodes to prevent contact therebetween.

In Figure 6 I have shown my invention as it may be applied to a wet type of condenser comprising a container for electrolyte 35 constituting the cathode of the condenser and retaining an electrolyte in liquid form indicated at 38 in which the anode 31 is immersed. The anode may be prevented from making contact with the cathode by a spacer 38 and may be supported within the container by a riser or terminal 39 extending through a rubber grommet 40 clamped securely within the depending neck portion 4| of the container. In this type of condenser the electrode may consist of any suitable base preferably a flexible fabric or paper sprayed on one or both sides with conductive layers 42 of finely divided film forming metal such as aluminum. The riser 39 preferably consists "or an aluminum rod spot welded to the sprayed surface 42 as indicated diagrammatically at 44. Preferably this electrode also is provided with conductive paths 45 extending longitudinally of the electrode from the end adjacent the riser to the opposite end and produced as described above by welding the sprayed particles in the paths together into a compact mass having very low electrical resistance. In this type of electrode I preferably employ a plurality of transversely extending conductive paths or welded areas 81, These paths or areas function not, only to improve the conductivity of the electrode and to uniformly distribute the current therethrough but also function to strengthen the electrode so that it can be rigidly supported within the container. With this type of construction an electrode consisting of two thin layers of sprayed material deposited on a fiexible base such as thin cloth or perforated paper can be wound into spiral form and inserted into a container to economically produce a wet type condenser having very desirable electrical characteristics and also having sumcient mechanical strength to resist the jolts and jars ordinarily encountered in service and in shipment.

In some instances it may be desirable merely to provide the sprayed layer or layers with :1 number of spots or small areas of increased density and conductivity. Such areas may be conveniently formed by a spot welding machine and function to improve the conductivity of the electrode and to securely hold the sprayed layers to the base. This type of construction may be employed with any suitable base material sprayed either on one or both sides but I find it especially advantageous with thin aluminum foil provided with sprayedlayers on one or both sides. Such an electrode is illustrated in Figure 9 and comprises a base of fabric, paper, aluminum foil or other suitable material 50 having spray-deposited surfaces and preferably provided with perforations i to improve the circuation of an electrolyte. The spray-deposited layers are subjected to the spot welding operation in a number of areas as indicated diagrammatically at 52. The riser 39 may be welded to one of the sprayed surfaces as at M. This type of construction is especially advantageous in conjunction with electrodes having bases of aluminum foil because of the improved adherence obtained between the foil and the sprayed layer or layers and the increased flexibility of the sprayed layers obtained by the welding operation. With this type of construction the electrode can be bent into spiral or other shapes without dislodging the sprayed layers from the foil.

A further modified form, shown herein as adapted for use in wet condensers, but also adaptable for dry condensers, is illustrated in Figures 10 and 11. In this modification, the electrode consists of a self-supporting layer of sprayed material 80. To produce this type of layer a spraydeposit may be deposited upon a moving base formed of a material to which the sprayed layer will not adhere such as a metallic cylinder coated with oil or grease, and continuously stripped therefrom. The material is preferably deposited in a layer having greater thickness than is usually employed, and the stripped layer is then subjected to the welding operation to produce areas of greater density and strength and higher conductivity extending preferably in two directions as indicated by lines 6| and 62. The terminal or riser 39 may be welded directly to the sprayed material as described above and as indicated at 44. By this construction an extremely efficient electrode may be economically produced, as the electrolyte can penetrate and permeate the porous sprayed material from both sides, and the cost of the base material is eliminated.

Under some circumstances it may be desirable to improve the conductivity and strength of the electrode embodying the sprayed layers by welding a conductive metallic strip, wire or rod along the sprayed surface. Further it may be desirable to build up a single electrode by welding together a number of electrodes having sprayed surfaces thus producing a porous mass of film forming material and obtaining an electrode having very high capacity in comparison with the volume which it occupies. Both of these features are illustrated in the electrode shown in Figures 12 and 13, but it is to be understood that the features can be used separately as well as together.

In this modification of my invention the electrode is shown as comprising two cloth strips Hi and II each provided with sprayed layers on the opposite sides thereof as indicated at l2, 13, It and 15. To increase the conductivity and emciency of the electrode, as well as to strengthen it, a conductive metallic strip shown in the drawings as a piece of foil 16 may be extended longitudinally of the cloth strips and disposed between them and welded to the inner sprayed layers 13 and M as indicated diagrammatically at H. Further conductive paths may be provided by subjecting both strips to simultaneous welding operations as described before to produce welded paths l8 and 19. It is to be understood that if desired two or more sprayed strips may be welded together as indicated at 18 and 79 without the use of a conductive metallic strip and further that the metallic strip may be utilized in conjunction with an electrode comprising a single strip of material, the metallic strip in that case being welded to one of the sprayed surfaces of the electrode.

Preferably electrodes of this type are provided with a number of perforations as indicated at 80 to assist in the fiow of the electrolyte in the condenser and to permit the electrolyte to permeate the assembled electrode so that all of the film forming area thereof may be used eifectively.

All of the various types of electrodes described herein may be made of aluminum or other film forming metal and provided with dielectric films as described above if required by the service for which they are intended. Filmed electrodes made according to the various forms of my invention described herein are especially advantageous because of the great eflective area of the film, and because the electrolyte can penetrate and permeate the spray deposited layers.

By my invention the terminal members for the electrode plates can be economically secured to the conductive areas of the plates in a fashion that insures proper connection between the active surfaces of the plates and the terminals and reduces the electrical resistance ordinarily encountered at the point of connection between the terminal and such sprayed areas. My invention further provides electrodes having surfaces composed of finely divided cohering metallic particles which have low resistance because of the conductive paths extending therethrough and which are extremely efficient in service because the conductivity is such that the current density throughout the electrodes or plates is substantially uniform. The compacted, fused, or welded areas or paths, in addition to increasing the conductivity of the sprayed layer, give it additional mechanical strength, and if a supporting base is employed improve the adherence of the layer thereto. My invention is useful in conjunction with electrodes or plates having a sprayed metallic surface regardless of the materia1 employed as the base on which the sprayed material is deposited. For example, the invention is useful in connection with electrodes having bases made of rigid materials such as porcelain or glass. Terminal connections for electrodes embodying my invention may be made rapidly and economically, and the conductive paths may be formed at a very low cost as they require only a, simple welding operation and involve no additional material.

In the foregoing specification I have described only preferred forms of my invention in their application to electrical condensers. However, those skilled in the art will appreciate that my invention may be modified in various ways, only some of which have been specifically mentioned herein and may be applied to diflerent types of electrical devices, all without departing from the spirit and scope of my invention. Therefore it is to be understood that my patent is not limited to the specific forms described herein or in any manner other than by the scope of the appended claims when given the range of equivalents to which my patent may be entitled.

I claim:

1. An electrode terminal assembly comprising an electrode aving a conductive layer of finely divided metallic particles and a terminal tab comprising a cloth strip having a conductive layer of metallic particles deposited thereon, the conductive layer on said terminal tab being welded to the conductive layer of said electrode.

2. An electrode for electrolytic condensers comprising a base of non-conducting material having atJeast a portion of the area thereof coated with a conductive layer of finely divided metallic particles, and a terminal for connecting said electrode to an external circuit, said electrode having at least one path of greater conductivity than said layer extending from a region adjacentsaid terminal to a region remote from said terminal.

3. An electrode for an electrolytic condenser, comprising a spray-deposited layer of finely divided cohering particles of film forming metal reinforced by areas comprising spray-deposited particles fused together into substantially integral masses.

4. An electrode for an electrolytic condenser comprising a spray-deposited layer of finely divided cohering particles of film forming material and a terminal for connecting said electrode to an external circuit, there being a path of greater conductivity and strength extending along said layer, said path being of a lesser area than said layer.

5. An electrode for electrolytic devices comprising a porous base of non-conducting material, a portion of the area of which is coated with a conductive layer of finely divided metallic particles, the particles in a portion of said layer being fused together into a form more dense than the remainder of said layer.

6. An electrode for electrolytic condensers comprising a base of non-conductive material having at least a portion of the area thereof coated with a conductive layer of finely divided metallic particles, said electrode having at least one path of greater conductivity than said layer extending along said layer and throughout a substantial portion thereof.

7. In an electrolytic condenser, an electrode comprising a fiexible porous base having at least a portion of the area of both sides thereof coated with conductive layers of finely divided metallic particles, and a terminal for connecting said electrode to an external circuit, said electrode having at least one, path of greater conductivity than said layers extending along said electrode from a region adjacent said terminal to a region remote from said terminal, said path comprising particles of said layers welded to each other through the interstices of said porous base.

8. An electrode for electrolytic condensers comprising a base having at least a portion of the area coated with a conductive layer of finely divided metallic particles, and a terminal welded to said layer for connecting said electrode to an external circuit, said electrode having at least one path of greater conductivity than said layer extending from a region adjacent said terminal to a region remote from said terminal, said path comprising particles of said layer welded to each other into a substantially integrated mass.

9. An electrode for electrolytic condensers com-.

prising a mesh fabric base having at least a portion of the area of both sides thereof coated with conductive layers of finely divided metallic particles, and a terminal for connecting said electrode to an external circuit, said electrode having at least one path of greater conductivity than said layers extending from a region adjacent said terminal to a region remote from said terminal, said path comprising particles of said layers welded to each other through the interstices of said fabric base.

10. An electrode for electrolytic condensers comprising a flexible porous base having a portion of the area of both sides thereof coated with a conductive layer of finely divided metallic particles, a terminal for connecting said electrode to an external circuit comprising a conductor weld ed to one of said conductive layers, the other of said conductive layers being compacted and welded into electrical contact with the first mentioned of said layers, through the interstices of the porous base in the region of the weld, and at least one path of greater conductivity than said layers extending from a region adjacent said terminal to a region remote from said terminal, said path comprising compacted particles of said layers welded to each other through the interstices of said porous base.

11. An electrode or plate comprising at least two separately formed, juxtaposed layers of finely divided cohering metallic particles, and a metallic conductor disposed between said layers and welded thereto.

12. An electrode comprising a layer of finely divided metallic particles having a terminal, and a metallic conductor extending along said layer and welded thereto.

13. An electrode or plate comprising a plurality of strips of flexible base material each having a spray-deposited layer of finely divided metallic particles thereon, the spray deposited layer on one strip being welded to the spray deposited layer on an adjacent strip.

14. The method of making electrodes or plates which includes the steps of producing a spraydeposited layer of finely divided cohering metallic particles and thereafter providing said layer with a path of increased strength and conductivity by welding together the particles in said path.

15. The method of making electrodes or plates which includes the steps of spraying finely divided particles of molten metal upon a base, removing the deposited layer from the base, and fusing the particles in a portion of said layer together.

16. The method of making electrodes orplates which includes the steps of spraying finely divided particles of molten metal upon a suitable base to provide a conductive layer of cohering metallic particles, and thereafter subjecting a. narrow area of said layer to additional heat to weld together the particles in such area to produce a narrow path of greater conductivity than the remaining portion of said layer.

17. The method of making electrodes or plates which includes the steps of spraying finely divided particles of molten metal up'on opposite sides of a thin, porous base to provide conductive layers of cohering metallic particles on both sides thereof, and thereafter subjecting adjacent narrow areas of said layers to heat to weld together the particles in such areas through the interstices of the base to produce a narrow path of greater conductivity than the remaining portions of said layers,

18. An electrode for electrolytic devices comprising a layer of metal characterized by a certain ratio of surface area to volume and a contiguous contacting deposit of film-forming metal suspended in an open mesh fibrous normally non-conducting material and characterized by a much higher ratio of surface area to volume of metal.

19. An electrode for electrolytic condensers comprising at least two layers of fibrous flexible material disposed in face to face contact and a multiplicity of particles of film-forming metal adhering to the fibers of said layers and an additional metallic conductor between said layers and in electrical contact with the particles of film-forming metal.

20. An electrode for electrolytic condensers comprising at least two layers of fibrous flexible material disposed in face-to-face contact and a multiplicity of particles of film-forming metal adhering to the fibres of said layers and to each other.

21. An electrode for electrolytic condensers comprising at least two layers of fibrous flexible material disposed in face-to-fsce contact and a multiplicity of particles of film-forming metal adhering to the fibres of said layers and to each other, said particles also serving to bond said layers together.

22. An electrode for electrolytic condensers comprising at least two layers of fibrous flexible material disposed in i'ace-.-to-i'ace contact and a multiplicity of particles of aluminum adhering to me fibres of said layers and to each other.

23. An electrode for electrolytic condensers comprising at least two layers or cloth disposed in face-to-face contact and a multiplicity of particles of film-forming metal adhering to the fibres of said layers and to each other.

24. An electrode for electrolytic condensers comprising at least two layers or cloth disposed in Iace-to-face contact and a multiplicity or particles of film-forming metal adhering to the nor-es of said layers and to each other, said particles also serving to bond said layers together.

25. An electrode for electrolytic condensers comprising at least two layers of fibrous flexible material disposed in face-to-race contact and a mult plicity or particles of him-forming metal adhering to the fibres of said layers and to eacn other and an additional metallic conductor between said layers and in contact therewith.

26. An electrode 101 l electrolytic condensers comprising at least two layers or nbrous flexible material disposed in face-to-i'ace contact and a multiplicity of particles of film-forming metal adhering to the nbres of said layers and to each other and an additional metallic conductor between said layers and in contact therewith, said particles also serving to bond said layers to said conductor.

27. An electrode for electrolytic condensers comprising a layer of fibrous flexible material disposed in face-to-face contact with a supplemental electrode of film-forming metal, and a multiplicity of particles of film-forming metal adhering to the fibres or said layer and to each other, said particles also serving to bond said layer to said supplemental electrode.

28. A film-forming electrode comprising a layer of cloth disposed in face-to-face contact with a sheet of aluminum, and a multiplicity of aluminum particles adhering to the fibres of said cloth and to the face or said sheet, said particles binding said cloth to said sheet.

29. An electrode for electrolytic devices comprising a layer of film-forming metal characterized by a certain ratio of surface area to volume and a conti uous contacting deposit of said metal s spended in a loose mesh fibrous non-metallic material and characterized by a much higher ratio of surface area to volume of metal, said de- 1ggrsit being of greater extent than said low ratio 30. An electrode for electrolytic condensers comprising a spray deposit of film-forming metal on an open mesh fibrous base, said deposit having a porosity greater than the porosity of such a deposit on a continuous solid surface and a conducting layer in intimate contact with said deposit at points distributed over a substantial portion of its surface.

31. An electrode for electrolytic condensers comprising a porous wick-type layer or film- !orming metal on an open mesh fibrous base and contiguous conductive layer in intimate contact therewith.

JOSEPH BARRY BRENNAN.