Corrosion inhibitor system for alkaline aluminum cells

Claim 2

A GALVANIC CELL COMPRISING AN ALUMINUM ANODE, A CATHODE, AND AN ELECTROLYTE IN CONTACT WITH SAID ANODE AND SAID CATHODE, SAID ELECTROLYTE COMPRISING AN AQUEOUS SOLUTION OF AN ALKALI METAL HYDROXIDE AND A CORROSION INHIBITOR SYSTEM IN AN AMOUNT EFFECTIVE TO INHIBIT CORROSION OF SAID ALUMINUM ANODE WHEN SAID CELL IS ON OPEN CIRCUIT AND WHEN SAID CELL IS DISCHARGING, SAID CORROSION INHIBITOR SYSTEM COMPRISING (A) AN ALKALI METAL CITRATE, AND (B) AT LEAST ONE COMPOUND SELECTED FROM THE GROUP CONSISTING OF LEAD COMPOUNDS AND TIN COMPOUNDS.

Claim 3

The galvanic cell of claim 1 wherein said alkali metal hydroxide is potassium hydroxide.

Claim 4

The galvanic cell of claim 1 wherein the lead compounds are selected from the group consisting of alkali metal plumbites, alkali metal plumbates, lead oxide, and lead acetate, and wherein the tin compounds are selected from the group consisting of alkali metal stannates and tin oxide.

Claim 5

The galvanic cell of claim 2 wherein the lead compounds are selected from the group consisting of alkali metal plumbites, alkali metal plumbates, lead oxide, and lead acetate, and wherein the tin compounds are selected from the group consisting of alkali metal stannates and tin oxide.

Claim 6

The galvanic cell of claim 1 wherein the corrosion inhibitor system is potassium citrate plus at least one number selected from the group consisting of lead acetate and potassium stannate.

Claim 7

The galvanic cell of claim 2 wherein the corrosion inhibitor system is potassium citrate plus at least one number selected from the group consisting of lead acetate and potassium stannate.

Claim 8

The galvanic cell of claim 1 wherein the alkali metal citrate is employed in the electrolyte in an amount within the range of from about 0.5 to about 10 weight per cent, wherein the tin compound is employed in the electrolyte in an amount within the range of from about 0.5 to about 5 weight per cent, and wherein the lead compound is employed in the electrolyte in an amount within the range of from about 0.1 to aboUt 2 weight per cent, all percentages being based upon weight of electrolyte.

Claim 9

The galvanic cell of claim 2 wherein the alkali metal citrate is employed in the electrolyte in an amount within the range of from about 0.5 to about 10 weight per cent, wherein the tin compound is employed in the electrolyte in an amount within the range of from about 0.5 to about 5 weight per cent, and wherein the lead compound is employed in the electrolyte in an amount within the range of from about 0.1 to about 2 weight per cent, all percentages being based upon weight of electrolyte.

Claim 10

The galvanic cell of claim 3 wherein the alkali metal citrate is employed in the electrolyte in an amount within the range of from about 0.5 to about 10 weight per cent, wherein the tin compound is employed in the electrolyte in an amount within the range of from about 0.5 to about 5 weight per cent, and wherein the lead compound is employed in the electrolyte in an amount within the range of from about 0.1 to about 2 weight per cent, all percentages being based upon weight of electrolyte.

Claim 11

The galvanic cell of claim 4 wherein the alkali metal citrate is employed in the electrolyte in an amount within the range of from about 0.5 to about 10 weight per cent, wherein the tin compound is employed in the electrolyte in an amount within the range of from about 0.5 to about 5 weight per cent, and wherein the lead compound is employed in the electrolyte in an amount within the range of from about 0.1 to about 2 weight per cent, all percentages being based upon weight of electrolyte.

Claim 12

The galvanic cell of claim 5 wherein said potassium citrate is employed in said electrolyte in an amount within the range of from about 0.5 to about 2 weight per cent, wherein said potassium stannate is employed in said electrolyte in an amount within the range of from about 0.5 to about 2 weight per cent, and wherein said lead acetate is employed in said electrolyte in an amount within the range of from about 0.5 to about 2 weight per cent, all percentages being based on said electrolyte.

Claim 13

The galvanic cell of claim 11 wherein said alkali metal hydroxide is potassium hydroxide.

Claim 14

The galvanic cell of claim 1 wherein the cathode is an oxygen-depolarized cathode.

Claim 15

The galvanic cell of claim 2 wherein the cathode is an oxygen-depolarized cathode.

Claim 16

A galvanic cell comprising an aluminum anode, a cathode, and an electrolyte in contact with said anode and said cathode, said electrolyte comprising an aqueous solution of an alkali metal hydroxide and a corrosion inhibitor system comprising (a) an alkali metal citrate selected from the group consisting of sodium citrate and potassium citrate, in an amount within the range of from about 0.5 to about 10 weight per cent, and (b) at least one compound selected from the group consisting of lead compounds in an amount within the range of from about 0.1 to about 2 weight per cent, and tin compounds in an amount within the range of from about 0.5 to about 5 weight per cent, all percentages being based upon weight of electrolyte.

Claim 17

A galvanic cell comprising an aluminum anode, a cathode, and an electrolyte in contact with said anode and said cathode, said electrolyte comprising an aqueous solution of an alkali metal hydroxide and a corrosion inhibitor system comprising (a) an alkali metal citrate selected from the group consisting of sodium citrate and potassium citrate, in an amount within the range of from about 0.5 to about 10 weight per cent, and (b) at least one compound selected from the group consisting of lead compounds in an amount within the range of from about 0.1 to about 2 weight per cent, and tin compounds in an amount within the range of from about 0.5 to about 5 weight per cent, all percentages being based upon weight of electrolyte.