US1437603A - Coated dry cell electrode - Google Patents

Description

- and RAYMOND (l. BENNER, citizens of the Patented es. 5, 1922.

STATES- PATENT OFFICE.

ANNAYA. MACKENZIE, OF ELMHURST, AND RAYMOND C. BENNER, OF BAYSIDE, YORK, ASSIGNORS TO UNION CARBIDE & CARBON RESEARCH LABORATORIES,' INC.,

.5. CORPORATION OF NEW YORK.

COATED DRY CELL ELECTRODE.

. No Drawing.

To all whom it mayconcern: Be it known that We, ANNA A. MCKENZIE United States, residing at Elmhurst and Bayside, in the county of Queens and State of New York, have'invented certain new and useful Improvements in Coated Dry Cell Electrodes, of which the following is a specifloat-ion.

This invention relates to dry cells and has particular reference to the formation of a layer of gelatinized material upon one of the electrodes of such" cells, prior to the assembly of the electrodes therein. The invention is especially applicable to the manufacture of dry cells of the type in which relatively easily disintegrated depolarizing bobbins are used.

The method as above broadly outlined is disclosed in United States Patent 1,295,475, dated Feb. 25, 1919, and 1,375,202, dated April 19, 1921, both granted to H. F. French and R. G. Benner. According to these patents, a film or layer of paste is applied to substantially the entire inner surface of zinc cups and is gelatinized thereon by suitable application of heat. In this manner the electrode is provided with a tough, tenacious coating. The procedure described makes it possible to use bobbins without the sustaining fabric Wrapping which is ordinarily required to prevent detached particles of depolarizer from reaching the zinc and there forming centers for destructive local action. The elimination of the Wrapping results in an improvement in the service characteristics of the cell and in a large decrease in the cost of production.

In the application of R. C. Benner, Serial No. 450,073, filed March 5, 1921, there is described another method of obtaining these advantageous results, comprising applying cereal paste to the bobbin and gelatinizing the paste by suitable heat treatment.

According to the present invention, the

Application fiIed March 27, 1922. Serial No. 547,226.

moistened surface and is gelatinized by the chlorid to form a tough layer adherent to the zinc wall and base of the container. The concentration of the gelatinizing solution may vary within Wide limits, say from about 30% up to saturation. We prefer to use solutions containing about 40% of zinc chlorid. If rapid gelatinization is required,

thedmore concentrated solutions should be use The chlorid and paste may be conveniently applied by spraying. The spray should be so directed that no layer of paste will be formed adjacent the top of the container, as this interferes with the application of the plastic seal. The amount of starch should in general be not substantially in excess of that which will form a coherent layer. Other methods may of course be adopted for distributing the liquids. For example, they may be applied by brushing, or by filling the zinc container and removing the surplus by decantation, suction, or the like.

In some cases, also, the paste may be ap plied first to the zinc and then treated with the gelatinizing solution. Or the gelatinizing solution may be applied, covered with paste, and more solution then added to toughen the inner surface of the paste layer. Alternatively, dry flour, corn meal or other cereal may be used instead of paste.

After the formation of the gelatinized layer, the bobbin is inserted axially in the container. and electrolyte paste is then filled into the annular space between these elements. A suitable amount of paste may be left in thecontainer, and displaced into operative position by inserting the bobbin. If raw flour paste is used, as is customary, the cell may be placed in hot water to gelatinize it. Preferably, however, the paste contains sufficient zinc chlorid, or other gelatinizing.

reagent, to insure its setting into a solid mass. The cell may be completed in the usual manner by placing sawdust, paoer, or the like, over the bobbin, and applying a plastic sealing material.

Instead of lining the zinc containers with gelatinized paste, depolarizing bobbins may be coated therewith and equivalent results obtained. The bobbins may be moistened externally with zinc chlorid by spraying, dipping, or the like, and dry cereal or cereal paste may then be applied in any suitable way. A tough coating is thus formed upon the bobbin, effectively preventing the crumbling of its surface and enabling it to be safely handled and assembled with the other cell elements under conditions of manufacture on a large scale.

It is preferred to apply the gelatinizin'g solution first, thenthe cereal, but this procedure may be reversed. A single application of gelatinizable material is generally sufficient to secure a satisfactory coating, but further applications, with suitable addition. of zinc chlorid or the like, may of course be made. In some cases enough gelatinizing solution may be incorporated With the mix to toughen cereal applied to the surface of the molded bobbin.

Zinc chlorid may be replaced'by various other gelatinizing agents. Calcium chlorid, for example, may be used. In general, any material capable of gelatinizing cereal paste with reasonable rapidity, and not having a deleterious effect on the cell, may be used. Starch paste is Well adapted for most purposes, and cereal pastes and dry cereals in general are suitable. It will be understood that the basic idea of the present invention is the chemical gelatinization of a protective layer on dry cell electrodes, and various means, other than those described, for acmemos sing agent into reactive relation thereon.

2. Process of forming a protective layer upon a dry cell electrode, comprisimg applyin; a gelatinizing reagent to such electrode, and*d'i'stributing a gelatinizable material thereupon.

3. Process of forming a protective layer upon the inner surface of a zinc container electrode. comprising applying a gelatinizing reagent to such electrode surface. and distributing a gelatinizable material thereupon. I

4. The invention according to claim 3, in

which zinc chlorid is the gelatinizinp reagent.

5. Process of forming a layer of gelatinized paste upon the inner surface of a Zinc container electrode, comprising spraying zinc chlorid solution upon such electrode surface, and then spraying starch paste thereupon.

In testimony whereof, We aflix our signatures.

ANNA A. MACKENZIE. RAYMOND C. BENNER.