US1624460A - Depolarizer for primary batteries - Google Patents

Description

Patented Apr. 12 1927.

UNITED STATES PATENT OFFICE- GEORGE W. ARMSTRONG, OF FREMONT, OHIO, ASSIGNOR TO NATIONAL CARBON COM- PANY, INC, A CORPORATION OF NEW YORK. I

DEPOLARIZER FOR PRIMARY BATTERIES.

No Drawing.

This invention relates to improvements in sulfur-containing copper oXid depolarizers for electric batteries, and particularly for batteries composed of cells having a caustic alkali electrolyte.

It is known from the disclosure of United States Patent, 1,282,057 granted to R. IV. Erwin on Oct. 22, 1918, that the addition of sulfur to copper oxid depolarizers results in a material increase in the voltage and service life of. cells in which such depolarizers are used. The method heretofore used for incorporating sulfur with the copper oxid consists in mixing the required amount of dry sulfur flour with the oxid and then heating the mixture up to the softening or melting point of the sulfur.

My investigations lead me to believe that the above described method of sulphurizing results in the formation in the depolarizer of a considerable proportion of water-soluble sulphur compounds. By thoroughly washing sulphurized depolarizer I have been able to remove from it a variety of soluble sulphur compounds. The presence of such water-soluble sulphur compounds has been found under certainconditions to de detrimental to the operation of cells made up with depola-rizers containing them. Their elimination by washing eliminates the detrimental eifects alluded to above. I prefer, however, to prevent the formation of such soluble sulphur compounds, rather than to remove those which have been formed, and I find that it is difiicult to avoid the formation of the soluble compounds if the known method of sulphurizing is used.

My improved copper oxide depolarizer is characterized by the presence of a relatively small proportion of sulphur chemically combined. with the copper oxide and by substantial absence of sulphur-containing compounds soluble in the electrolyte.

My preferred method for incorporating sulfur with copper oxid in the insoluble form consists in agitating cupric oxid while passing in contact therewith a regulated flow of hydrogen sulfid gas. The flow of gas is controlled so as to prevent too great an evolution of heat, and is shut ofi when the amount of sulfur combined with the oxid reaches the desired amount. The best results have been obtained when the sulfur content was approximately 5%. However, it is to be understood that my invention is Serial No. 12,453.

not limited to this precise proportion since the sulfur content may be varied considerably from this proportion so long as all of the sulfur is present in a form insoluble in the electrolyte.

The temperature at which the sulfurizing is carried on should be as low as possible, although a satisfactory product may be obtained' anywhere within the range from approximately 0 C. to 100 C. 7

My improved depolarizer material may also be prepared by sulfurizing in the usual way, or by treating with hydrogen sulfid gas in excess, and then washing out the soluble sulfur compounds with hot water or other solvents. The washed material is found to possess properties similar to those possessed by the material prepared by my preferred method above described.

The improved depolarizer material may also be with other sulfur-containing gases than hydrogen sulfid. For example, sulfur dioxid may be employed. An aqueous solution of hydrogen sulfid has also been found effective.

Cells embodying my new depolarizer have been operated under conditions simulating those met with in actual signal operation over a period of six months and have shown throughout this period a voltage substan-.

tially greater than that shown by high voltage cells embodying the older kind of depolarizer and operated under the same conditions. The contrast was particularly marked during the early part of the test.

The superiority of the new depolarizer with respect to length of service and regularity of performance is particularly marked when cells in which it is used are operated under low temperature conditions.

Cells embodying my new depolarizer have shown marked improvement with respect to corrosion of the zinc plates, and are thus characterized by long service life.

Having described my invention what I claim is:

l. A depolarizing substance for electric batteries comprising copper oxid and sulfur combined therewith in a form insoluble in the electrolyte, said substance being substantially free from sulfur compounds soluble in the electrolyte.

2. A depolarizing substance for electric batteries comprising copper oXid and apprepared by treating copper oxid.

proximately 0.5% sullur tfilll lllltltl therewith in a torn: insoluble in the electrolyte, said substance being substantially free from sul lur con'ipounds soluble in the electrolyte.

3. In a primary battery with alkaline electrolyte, a negative element comprising copper oxid and sulfur combined therewith in a form insoluble in the electrolyte, said element being substantially free from snl'l'nr compouiulssoluble in the electrolyte.

l. in a primary battery with alkaline electrolyte. a negative element comprising cop per oxid and approximately 0.5% sulfur combined therewith in a form insoluble in the electrolvte said element being substantially free from sulfur compounds soluble In the electrolyte.

5. In a primary battery, an alkaline electrolyte. a zinc electrode and a negative elenient C(JllllJllSlllg copper oxide and sulfur coniliiined therewith in a form insoluble in the electrolyte, said element being substantially free. :Eroinsultur compounds soluble in the electrolyte.

(3. A process of pre hiring a depolarizer for electric batteries, which consists in treating copper oxid with a sulfur-containing gas in such amount and under such temperature conditions that substantially all of the sulfur combined with the copper oxid in a form insoluble in an alkaline electrolyte.

7. A process of preparing a clepolarizer for electric batteries, which consists in treating copper oxid with hydrogen sulfid in such amount and under such temperature conditions that substantially all of the sulfur is combined with the copper oxid in a form insoluble in an alkaline electrolyte.

8. A, process oil preparing a depolarizer for electric batteries, which comprises incorporating with copper oxitl sulfur in a form insoluble in an alkaline electrolyte and eliminating any soluble sulfur compounds which may be present.

In testimon whereof, I aflix my signatnre.

( 1 X )R( l E \V. ARMSTRONG.