US2829189A

US2829189A - Alkaline dry cell

Info

Publication number: US2829189A
Application number: US606087A
Authority: US
Inventors: Joseph J Coleman; Paul G Kort
Original assignee: Burgess Battery Co
Current assignee: Burgess Battery Co
Priority date: 1956-08-24
Filing date: 1956-08-24
Publication date: 1958-04-01
Anticipated expiration: 1975-04-01

Description

A ril 1, 1958 J. J. COLEMAN ET AL 2,829,189

ALKALINE DRY CELL Filed Aug. 24, 1956 26- a I 45 -12 Q0 5 -30 United States Patent ALKALINE DRY CELL v Joseph I. Coleman and Paul G. Kort, Freeport, 111., as-

signors to Burgess Battery Company, Freeport, 111., a,

corporation of Delaware Application August 24, 1956, Serial No. 606,087 3 Claims. (Cl. 136-107) This invention relates to current-producing primary electric cells, and'particularly to dry cells having an aqueous alkaline electrolyte.

In alkaline dry cells of the type described, gas is normally generatedv within the cell while it stands on open circuit and if such gas formation is not controlled, excessive pressure is created within the cell such that rupture of the cell enclosure takes place, or if such rupture does not occur, the gas pressure forces open the seal of theenclosure. In either event, escape of gas takes place regardless of the mechanical means employed to prevent such escape, and this is accompanied by escape of liquid components from the cell, which is the wellknown and objectionable phenomenon of cell leakage.

It is the principal object of the invention to provide a dry cell of the character describedin which the forma-- tion of gas within the cell is inhibited, with the result that excessive internal gas pressure is prevented and cell leakage is avoided.

Other objects of the invention will become apparent from the following description of an embodiment of the dry cell of the invention, which description is to be read in conjunction with the accompanying drawing showing an example of such acell, in whichvention, there are two open-top cups 12 'and arranged in mutually telescoping relation to form the enclosure for the cell. The inner cup 12 is composed of a suitable metal'such as steel and has its open top directed downwardly and has the major central portion of its bottom dished upwardly as shown to form the dished portion 14. Between' the dished portion and the cylindrical wall of inner cup 12is the annular'shoulder'17. The exterior surface of steel cup 12 may be nickel-plated if desired.

The interior surface of the dished portion 14 has an adherent coating 16 of zinc thereon, formed by plating "or other suitable method. Withinsaid dished portion 14 and resting in contact with zinclayer 16'is the negative electrode or anode 18 of the cell, said anode being composed of amalgamated zinc and preferably being in the form of a body of compressed amalgamated zinc,

particles. The amalgamated zinc powder is pressed into the dished portion 14 under sufiicient pressure that it remains firmly in place.

The outer cup 20 is composed of a suitable metal such as steel and has its open top directed upwardly. The exterior surface of steel cup 20 may be nickel-plated if desired. Between the cylindrical edge of the open top of inner cup 12 and the bottom wall of outer cup 20 is an annular sealing gasket 22 of a suitable sealing composition such as neoprene, polyethylene, or polyvinyl chloride. Such gasket 22 is shaped in cross section in the form of a deep, narrow U, the base of the U being under pressure between the edge of the inner cup 12 cup'34 which is also composed of steel.

I 2,829,189 Patented Apr. 1, 1958 and the bottom of the outer cup 20, the outer leg of the U extending upwardly in contact with the'exterior surface of the cup 12 within the space between said cup and outer cup 20, and the inner leg extending upwardly in contact with the interior surface of said cup 12.

The upper end portion of the cylindrical wall of outer cup 20 is turned inwardly to form the flange 24 which clamps the two

cups

12 and 20 together. An annular gasket 26 composed of vulcanized fibre, modified polystyrene, or other suitable inert non-yielding material is arranged between shoulder 17 and flange 24, said flange being turned down upon gasket 26 with sufiicient pressure to hold inner cup 12 in sealing engagement with gasket 22 to form "a substantially liquidandgas-tight seal. Gasket 26' holds the inner and outer cups apart to electrically insulate them and to provide the annular space 28 within which is the mass of absorbent material 30 which may be absorbent paper such as blotting paper. A small'opening 32 may be provided in the cylindrical wall of outer cup 20 to serve as a gas vent to atmosphere. Within outer cup 20 and fixed to the bottom wall of the latter as by welding or soldering is a third open-top The exterior diameter of cup 34 is slightly less than the interior diameter of cup 12 to leave a narrow annular space between the two members. Cup 34 is shallow in relation to the'height of

cups

12 and 20 to leave a substantial space'between the top of said cup 34 and the surface of anode 18. I

Within cup 34 is the depolarizing cathode 36 which is composed of a mixture of powdered suitable oxygenyielding substance such as mercuric oxide, mercurous oxide, silver oxide, silver peroxide, cupric oxide, cuprous oxide, or other readily-reducible oxygen-yielding compound, or mixtures of such compounds, and a suitable conductive substance such as micronized graphite. The proportion of conductive substance may be varied from approximately 5% to approximately 15% by weight of the depolarizer composition, the remainder being oxygenyielding substance. An example of a preferred de polarizer composition is one containing 90% by weight of powdered mercuric oxide and 10% of micronized graphite. The depolarizer composition is compressed into cup 34, the amount of composition being sufficient 'to fill cup 34 substantially level with the top'edge thereof.

Resting upon the top surface of the depolarizing cathode 36 and the upper edge of cathode cup 34 is'a relatively thin barrier disk 38 of a suitable ionically permeable material such as parchment paper, vinylidine resin, vinyl resin, or other suitable ionically permeable material which is resistant to the cell electrolyte and depolarizer. The edge of said disk 38 extends outwardly beyond the "side wall of cup 34 and into contact with gasket 22.

.Above the barrier disk 38 is the electrolyte-receptive body '40 which is composed of a suitable porous, absorbent electrolyte-resistant material, such as a body of matted cellulose fibers, which may be wood or cotton fibers. The body 40 is of cylindrical shape and preferably has a diameter smaller than the internal diameter of inner cup 12 whereby an annular space is left between the cup 12 and the body 40. The body 40 is under compression between the anode 18 and the barrier disk 38 and is sufiiciently porous as to be highly absorbent of the liquid electrolyte of the cell.

The electrolyte of the cell is contained in absorbed condition in the absorbent body 40. The electrolyte is an aqueous solution of a suitable alkaline substance, such as potassium hydroxide, sodium hydroxide, lithium hydroxide, or mixtures of such hydroxides. The amount of electrolyte and the proportions of alkali metal hydroxide therein may vary. By way of example, an amount of electrolyte equal to approximately 20% to 25% performance.

stances which are in solutio'nltherein. l the barrier 38 is liquidand ion-permeable. The electro- As used herein, and inthe claims appende term aluminum oxide. is deemed to i of th'e'weight ofthedepolarizer and an aqueous solu tion containing approximately 35% to 43% of KOH in water have been used and found to give satisfactory The barrier disk 38 miili tely porous and is p ermeable to' the liquid ofthe electrolyte: and to the sub- In other words,

lyte' and the ions thereof freely traverse said barrier but particles of the .depolarizer mixture 36 and of the anode 18 are prevented from passage therethruogh. The electrolyte-receptive element 40 is more coarsely porous and acts as a reservoir or medium fo -holding the electrolyte in a sub stantiallyimmobilizedjcondition,

In accordance with th'e present invention, a'substance is incorporated in' theelectrolyte which has the property of inhibiting gasformatio'n during periodswhen the cell stands on opencircuit, substance whichiha sl been found to exert a pronounced effect in inhibiting? such gas formation is aluminum oxide, Al O TheYhydfrous 7 form of aluminum oxide, Al,O '.3H O, sometimesQdesignated as aluminum hydroxide, Al(OH jandother hydrates of aluminum oxide are suitable for'. the lpurposes of the invention and effectively inhibit gas formation. ereto, the l "clude the hydrous forms thereof, including aluminum hydroxide 'lfl desired,

the gas inhibiting substance maybe initially lntroduced into the electrolyte as anhydrous aluminum '0 stance is required to accomplish the functionoflmilibiting gas formation. Anhydrous aluminum oxidejis only slightly soluble in the alkaline electrolyte, as 1; pla s containing 37% by weight of KOH and. 63% being saturated by 0.086 gramAl o' in 100" f water ms of electrolyte. In otherwords a saturated solution contains .086%"Al,05 in solution. Desirable 'gas inhibiting res ults are obtained by the use of aluminum oxides i if ficient in ainountto provide from to 100% saturation of the electrolyte, a range offrom0.0043 to 0.086 gram of aluminum oxide per 100 grams of electrolyte.

The mechanism by which the function of gas formation is accomplished is not understood, but this desirable result has been confirmed by experimentation.

The, gasket 22 forms a seal between the inner and If such escaping gas is accompanied by cell exterior of the. cell,

1 During operation of the cell, the anode 18 expands in size and maintains the electrolyte-receptive body 40 under compression'whe'reby the internal resistance is maintained at a low value.

In a comparative test to demonstrate the efliectiveness of the aluminum oxide in inhibiting gas formation in a preferred mode of practicing the invention, two batches of cells were constructedhaving the structure shown in Figs. 1 and 2 and having outside dimensions of Wm inch height and 1 inch diameter, and having as electrolyte an aqueous solution containing 37% of KOH and as depolarizingcathode a mixture of 90% of Hg() and 10% of micronized graphite. The structure of the cells and the components thereof were identical except that in one batch the eletcrolyte was saturated with anhydrous aluminum oxide and in the other such oxide was omitted.

All of the cellswere allowed to stand on open circuit at room temperature. After 2 hours, one of the cells which did not contain aluminum oxide in its electrolyte exuded liquid due to excessive'internal"ga's pressure,

and the other cells of the same batch similarly failed for of cells containing the aluminum oxide in the electrolyte showed no evidence of excessive internal gas pressure when 6 months"old,,and the Zincanodes showed no corrosionl. All of the cells when tested individually on closed circuits, initially delivered .05-.06 ampere through a resistance of 20 ohms, and after 6 months standing on open circuit, thecells containing aluminum oxide in the electrolyte delivered .05-.055 ampere through the same resistance.

Invention is claimed as follows:

1. Ina dry cell, anamalgamated zinc anode, a readily- "reducible oxygen-yielding depolarizingcathode and an alkaline electrolyte containing aluminum oxide in an amount from'about 0.0043 to about 0.086 gram per 100 grams of electrolyte dissolved therein as a means for inhibitinggas formation. 7 v R g g 2. In a dry cell, an amalgamated zinc anode, a depolariiing cathode comprising mercuric oxide, and an alkaline electrolyte containing aluminum oxide in an amountfrom about 0.0043 to about 0.086 gram per 100 grams of electrolyte.

3. In a dry cell, an amalgamated zinc anode, a depolarizing cathode comprising mercuric oxide, and an alkaline electrolyte containing potassium hydroxide and aluminum oxide in an amount from about 0.0043 to about 0.086 gram per 100 grams of electrolyte.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Bailar, Jr., J. C.: fEssentials of General Chemistry, D. C. Heath & Co., Boston, 1946, pp. 400-1.

Claims

1. A DRY CELL, AN AMALGAMATED ZINC ANODE, A READILYREDUCIBLE OXYGEN-YIELDING DEPOLARIZATING CATHODE AN AN ALKALINE ELECTROLYTE CONTAINING ALUMINUM OXIDE IN AN AMOUNT FROM ABOUT 0.0043 TO ABOUT 0.086 PER 100