US1370052A - Dry cell - Google Patents

Description

A. W. SCHORGER.

DRY CELL.

APPLICATION FILED JAN. 25, 1919.

1,370,052.. Patented Ma.r.1,191 21.

ATTORNEYS UNITED STATES PATENT OFFICE.

ARLIE WILLIAM SCHORGER, OF MADISON, WISCONSIN, ASSIGNOB TO BURGESS BATTERY COMPANY, OF MADISON, WISCONSIN, A CORPORATION OF WIS- CONSIN.

DRY CELL.

Patented Mar. 1, 1921.

Original application filed November 19, 1918, Serial No. 263,119. Divided and this application filed Jannary 25, 1919. Serial No. 273,020.-

T 0 all whom it may concern:

Be it known that I, ARLIE W. 'SoHoRoER, a citizen of the United States, residing at Madison, in the county of Dane and State of Wisconsin, have invented certain new and useful Improvements in Dry Cells, (divislon of application filed Nov. 19, 1918, Ser. No. 263,119;) and I do hereby declare the followin to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it I appertains to make and use the same.

Electric dry cells can be roughly grouped into two general classes. In the first class, as illustrated, for instance in Burgess and Hambuechen U. S. liatent Number 1,032,529, issued July 16, 1912, the zinc can is linedwith paper or other equivalent bibulous material and the so-called mix consisting of carbonaceous material, manganese-dioxid and the usual salts and moisture is tamped about a carbon rod, thereby forming the cathode which is spaced from the zinc or anode by the layer of moistened paper.

In the second class, the mix, before its introduction into the zinc can, is molded about the carbon rod to form a so-called core which, thou h fragile, is nevertheless capable of manipu ation on a factory basis. A suitable apparatus for thus molding the moist mix about a carbon rod is disclosed in U. S. patent to Hambuechen Number 1,232,297, issued July 3, 1917. The core so formed is next wrapped about with gauze,

cheesecloth or the like, held in place by rubber bands or by a wrapping of thread. as disclosed in Burgess U. S. Patent Number 1,162,449, issued November 30,1915. 40

The wrapped core is then introduced into the zinc can, and an electrolyte in the form of a gelatinizable paste is poured into the annular space separating the core from the tegration an wall of the zinc can. It is quite customary to gelatinize this paste by a cooking opera-,

tion, and the Ogauze wrapping prevents disinwashing away of the molded mix during the cooking, and. of course, prevents the mix from crumbling away anddropping into contact with the zinc during the preceding operation of assembly. These cells areordinarily said to be of the bag type because the gauze wrapping forms in effect a bibulous bag to hold the mix in position during assembly and during cooking of the gelatinizable electrolyte. After the electrolyte has been hardened to a jelly-like consistency, the gauze wrapping-is no longer essential, and in fact its presence in the cell presents some objections, as will be well understood by those skilled in the art.

The present invention relates to galvanic cells of the bag type and has as one of itsobjects the elimination of the gauze bag and the substitution for it during assembly of a hard, thin and porous covering preferably put on by dipping the molded core into a magma such as a mixture of plaster'of Paris and Water.

It is a further object of the present invention to simplify and cheapen the process of manufacture by eliminatin the expensive gauze bag and the tedious an expensive operations of wrapping the core with the gauze and binding it in place with a wrapping of thread or the like.

It is a further object to produce a finished battery of the bag type of high out- .for the other elements of the cell; 2""is' the gelatinized electrolyte; 3 is a carbon rod enveloped in the molded mix '4 of carbonaceous material, manganese dioxid, etc, and 5 Is the envelop orbag of hardened plaster -dip. The. carbon rod may have a brass terminal cap 6, a pitch seal 7-, a cardboard washer 8, and an an space 9, as 1s usual indry cell construction, and may be of any desired size, as, for instance, six inches high to conform w1th standard telephone practlce, or of a'much smaller size for use in battery hand lamps and like novelties;

The process of assembling the component parts to make a cell of this construction is as follows: The mix 4: is molded about the carbon rod 3 in a suitable tamping machine. as of the construction-shown in Hambuechen Patent 1,232,297, and the fragile core thus formed is dipped into a magma, preferably accordance with the vary consisting essentially of a suspension of.

' is used, a certain amount clings to the botillustrated diagrammatically in the drawing at 10, where the core rests on the zinc bottom of the can. These particles of sand then act to separate and insulate the core from the bottom of the zinc can and obviate the need for covering the zinc bottom with a disk of paraffin paper, as is common practice, or the need for impregnating the lower portion of the core with paraffin, as described in Burgess Patent 1,162,449. ing in l 'bor and some economy in material. After the core has become thoroughly hardened on the greasedplate or on the bed of sand, it is introduced into its zinc can and the electrolyte is poured into the annular space between the core and the Zinc can, in

tom of the core, as

sembling bag type cells. The gelatinizable electrolyte may consist of a mixture of' cereals and zinc and ammonium chlorids, capable of gelatinization on heatin though I prefer to use a water solution co t'aining about 25.5% of cereals, say, cornstarch and cornmeal, and 36.7% of zinc and ammonium chlorids, all at a temperature considerably lower than room temperature for this mixture, though not original with me, is of such a character as to function in advantageous manner as a part of the cell, more particularly because it gelatinizes without the need for a subsequent cooking operation.

The magma into which the cores are dipped to form the film which subsequently hardens to a coherent bibulous envelop may in composition, and there are hereinafter described several which are suitable, and some of which offer special advantages.

Plaster only-A mixture of water and plaster in suspension .forms a suitable dip. Thus I may use 225 grams plaster of Paris and 250 grams of water. A core dipped into such a suspension takes on a film which on drying hardens into a porous, continuous, strong cup or envelop completely surrounding the core. The proportion of plaster of Paris to water may be varied through relatively wide limits in order to vary the thickness of the hardened film, for the thinner the magma the thinner will be the film produced on the core. Another suitable mixor on a smooth bed of sand. This pre- There is thus obtained some sav-- usual .practice of asture consists of 20 grams zinc oxid; 20

point, in that the mixture sets relatively quickly inthe dipping vessel, thereby causing somewaste of material. I have discovered that these difficulties can be overcome by, the addition to the dip of a suitable salt to act as a retarder to the setting of the plaster.

Plaster and salt.-A suitable -dipping ma ma may consist of 225 grams of plaster of Taris and 225 cubic centimeters of 2% sodium borate solution. The sodium borate acts as a retarder to delay setting of the magma. For example, a plaster alone which would set in five minutes in the dipping vessel can be so retarded by the addition of a small amount of borax that it will not. set for ten to twenty hours. In a thin film on the cores, however, it will set in one hour, and this is rapid enough for commercial practice. Analogous salts of boric acid can likewise beused, and even other salts, so long as they would not be harmful in the borate is entirely harmless.

Plaster and colloidal suspensions-As a substitute for sodium borate or other salt to retard the setting of the plaster dip, I may use colloidal suspensions such as starch, agar agar and the like. In addition to prolongwhen acted on by zincchlorid has the property of swelling or expanding. If it is incorporated ter, it remains intact while the core is out of contact with the electrolyte. Whe'nthe electrolyte is poured around the core, the zinc chlorid of the electrolyte gradually attacksthe starch and expands the particles. This breaks up or shatters the core coating and allows a more intimate contact between the cathode mix and the electrolyte. This breaking up does not take place until after the paste has gelatinized or set, and consequently there is no danger that this rupture of the plaster coating will allow carbonaceous material or manganese depolarizer to pass over into direct contact with the zinc.

A mixture that I have found to give satisfactory results consists of 500 grams plaster and 700 cubic centimeters of a 2% starch solution. Or, I may use a magma consisting of 250 grams starch, 225 grams plaster and into the core coating with the plas- .agar, and 700 grams water.

650 cubic centimeters of 2% borax solution. As another example, I may use 20 grams plaster and 50 grams of starch suspended in 100 cubic centimeters of a 10% dextrin solution.

Other colloids will act similarly with other electrolytes, but the use of starch to be acted on by zinc chlorid in shattering the hardened di is the embodiment preferred by me.

hen agar agar is used as the colloidal suspension to prolong the time of setting, this shattering of the coating doesnot take place, for agar a ar is inert with respect .to the electrolyte. t does, however, produce a semi-permeable membrane which allows the transfer of ions, and with certain electrolytes and under certain conditions it may be desirable to have such a semi-permeable membrane rather than to have the coating broken up through expansion of some of its components. agar agar, a mixture of the following composition may here be mentioned. 500 grams plaster, as plaster of Paris; 7 grams agar As a modification of the procedure above outlined, I have found that the cores can be dried in air when suspended by the carbon electrode, and,therefore, need not rest on a greased plate, or on a layer of sand. This allows the coating to flow toward the bottom and harden into a nodule or enlargement as indicated dia'grammaticall at 11, Fig. 2.

As a result, the coating is t icker on the bottom or end of the cylinderthan it is on the sides. This acts as a spacer and keeps the core further from the bottom of the zinc can than it would be if the coating'were the same thickness throughout. If desirable, the bottom can be parafiined, as explained in Burgess Patent No. 1,162,449, to prevent excessive action, but satisfactory life of the battery is obtainable without doing this.

This method of making dry cells of the bag type eliminates the use of gauze,cheesecloth or like fabric, now expensive and diflicult to obtain, and likewise eliminates all of the hand labor of wrapping the cores and binding them with thread, and because of the extreme thinness of the plaster film there is made available for useful purposes a considerable space which otherwise would be occupied by'the inert cloth wrapping and its binder. With the gauze wrapping there is danger of the entrapment of air when the paste is'poured in and any bubble ofentrapped air not only cuts down the effective area of the electrode, but alse is "liable to set up local actions of an undesired character. With the smooth plaster film, there is no danger of air entrapment. The thickness of the film, being dependent on the viscosity of the magma into which the core is dipped, is

.under easy control, particularly when a retarde'r is used to delay setting ofthe dip.

As illustrative of the use of i A good contact is assured between the electro yte and the cathode, and this'is particularly the case when starch is incorporated in the coating, and by swelling under the action of the zinc chloridshatters the coating after the electrolyte has set to a consistency to hold the mix in position whether the coating is or is not present.

In practising the process above described and hereinafter claimed, various materials may be used for the dip and for the retarder and as a means for ultimately shattering the core, and I contemplate such changes in the process and in the materials used as reasonably come within the spirit and scope of the present invention as defined by the claims appended hereto.

I claim l. The method of dry-cell manufacture I ducing said coated core into a zinc can and pouring a gelatinizable electrolyte about said core; substantially as described.

2. The method of dry-cell manufacture which consists in compressing about a car- ,bon rod a moist, active mixture ofcarbonaceous material and manganese depolarizer to form a fragile dry-cell core, coating said core with a magmaof plaster and a suitable retarder to form a slow-setting bibulous envelop thereon, introducing said coated core into a zinc anode and pouring a gelatinized electrolyte about said core.

3. The method of dry-cell manufacture which'consists in arranging about a carbon 'rod a mixture of carbonaceous material and manganese depolarizer to form a dry-cell core, coatin said core with a magma of plaster of aris to which borax has been added, thereby forming a bibulous envelop on said core, introducing said coated core into a zinc can and pouring a gelatinizable electrolyte about said core.

4. The method of dry-cell manufacture which consists in compressing about a carbon rod a moist, active mixture of carbonaceous material and manganese depolarizer to form a fragile dry-cell core, coatingsaid corewith a magma of plaster containing starch and a suitable retarding salt thereby forming a bibulous envelop on said core, introducing said coated core into a zinc anode and pouring about said core and electrolyte adaptedto swell the starch particles of said envelop.

ter of Paris and 650 cubic centimeters of 2% borax solutlon, introducing said coated core into a zinc anode and pouring about said core an electrolyte capable of acting on said the core thus formed'to harden while resting on a surface of sand, in order that grains of sand may adhere to said envelop.

7. The method of making dry-cells which consists in dipping the molded cathode into a magma of plaster having a suitable admixture and then allowing the thin envelop thus formed to harden on the cathode, introducing the core so produced into a zinc electrode and pouring into the space between the core and the zinc electrode a. gelatinizable electrolyte containing zinc chlorid which acts on said admixture to effect ulti- V mately 21 more intimate contact between said electrolyte and said cathode, substantially as described.

8. The method of making dry-cells which nizable electrolyte containing ,zinc chloridto act on the starch and thus disrupt the envelop to effect a more intimate contact between said electrolyte and said cathode; substantially as described.

In testimony whereof I aflix my signature.

ARLIE WILLIAM SCHOR-GER. V

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