Voltage and reduced polarization within mercury free zinc air cells
View Patent ↗The present disclosure is directed to a zinc air cell with improved voltage and reduced polarization. The combination of an anode corrosion inhibitor with a surfactant system yields enhanced cell voltage and capacity for the cell that are above the individual contributions of the corrosion inhibitor and the surfactant system.
1. A zinc-air cell comprising:
a cathode;
an anode comprising an anode mix, wherein the anode mix comprises a polyaniline corrosion inhibitor and an electrolyte comprising a surfactant system; wherein the surfactant system comprises a hexyl diphenyl oxide disulfonic acid surfactant and at least one amphoteric surfactant; and
a separator disposed between the anode and the cathode;
wherein the hexyl diphenyl oxide disulfonic acid surfactant is present in an amount of from about 500 ppm to about 5,000 ppm, by weight of the electrolyte;
the at least one amphoteric surfactant is present in an amount of from about 500 ppm to about 5,000 ppm, by weight of the electrolyte; and
the polyaniline is present in an amount of from about 100 ppm to about 500 ppm, by weight of the anode mix.
2. The zinc-air cell of claim 1 , wherein the at least one amphoteric surfactant has a formula
wherein:
R 1 is an alkyl group having between 8 and 30 unbranched carbon atoms;
R 2 is an alkyl group having between 1 to about 6 unbranched carbon atoms, optionally substituted with 1 or more hydroxyl substituents;
R 3 is selected from a polyethylene oxide group having between 3 and 40 ethylene oxide units and a polypropylene oxide group having between 1 to 10 propylene oxide units; and
X is an anionic acid group, an anionic acid ester, or an alkali metal salt of an anionic acid or acid ester.
3. The zinc-air cell of claim 1 , wherein the at least one amphoteric surfactant has a formula
wherein
R 4 is an unbranched alkyl group having between 8 and 30 unbranched carbon atoms that form an aliphatic fatty amine when bound to the nitrogen atom;
R 5 is selected from a polyethylene oxide group having between 3 and 40 ethylene oxide units and a polypropylene oxide group having between 1 and 10 propylene oxide units; and
R 6 is selected from hydrogen, a polyethylene oxide group having between 3 and 40 ethylene oxide units and a polypropylene oxide group having between 1 and 10 polypropylene oxide units.
4. The zinc-air cell of claim 1 , wherein the surfactant system comprises a mixture of amphoteric surfactants, wherein the first amphoteric surfactant has a formula
wherein:
R 1 is an alkyl group having between 8 and 30 unbranched carbon atoms;
R 2 is an alkyl group having between 1 to about 6 unbranched carbon atoms, optionally substituted with 1 or more hydroxyl substituents;
R 3 is selected from a polyethylene oxide group having between 3 and 40 ethylene oxide units and a polypropylene oxide group having between 1 to 10 propylene oxide units; and
X is an anionic acid group, an anionic acid ester, or an alkali metal salt of an anionic acid or acid ester; and the second amphoteric surfactant has a formula
wherein
R 4 is an unbranched alkyl group having between 8 and 30 unbranched carbon atoms that form an aliphatic fatty amine when bound to the nitrogen atom;
R 5 is selected from a polyethylene oxide group having between 3 and 40 ethylene oxide units and a polypropylene oxide group having between 1 and 10 propylene oxide units; and
R 6 is selected from hydrogen, a polyethylene oxide group having between 3 and 40 ethylene oxide units and a polypropylene oxide group having between 1 and 10 polypropylene oxide units.
5. The zinc-air cell of claim 1 , wherein the surfactant system comprises a mixture of amphoteric surfactants, wherein the mixture comprises one or more polyethoxylated fatty amino carboxylates and one or more polyethoxylated fatty amines.
6. The zinc-air cell of claim 1 , wherein the polyaniline is a polyaniline emeraldine base.