Fluorosurfactant as a zinc corrosion inhibitor
View Patent ↗An alkaline electrochemical cell, preferably a zinc/air cell which includes a container; a negative electrode, a positive electrode, wherein said negative electrode and said positive electrode are disposed within the container, a separator located between the negative electrode and the positive electrode, and an alkaline electrolyte, wherein the negative electrode comprises zinc, and a branched chain fluorosurfactant. The fluorosurfactant is preferably a sulfotricarballylate surfactant with multiple fluorinated end groups.
1. An alkaline electrochemical cell, comprising:
a container, a negative electrode, a positive electrode, wherein said negative electrode and said positive electrode are disposed within the container, a separator located between the negative electrode and the positive electrode, and an alkaline electrolyte, wherein the negative electrode comprises zinc and a sulfotricarballylate surfactant;
wherein the surfactant forms at least one monolayer on the surface of said zinc.
2. The cell according to claim 1 , wherein the sulfotricarballylate is characterized by the formula
and where Z 1 ═Z 2 ═Z 3 ═F 3 C(CF 2 ) ai (CH 2 ) bi (O(CH 2 ) ci ) di —, where ai=1-2, bi=1-2, ci=2, and di=1-3.
3. The cell according to claim 1 , wherein the sulfotricarballylate is characterized by the formula
and where Z 1 ═Z 2 ═Z 3 ═F 3 C(CF 2 )(CH 2 )(O(CH 2 CHCH 2 CH 3 )).
4. The cell according to claim 1 , wherein the sulfotricarballylate contains three fluorinated end groups.
5. The cell according to claim 1 , wherein the sulfotricarballylate is in the form of a mixture.
6. The cell according to claim 1 , wherein the sulfotricarballylate is present in an amount from 10 to 200 ppm based on the total weight of the zinc.
7. The cell according to claim 1 , wherein the sulfotricarballylate is present in an amount from 10 to 100 ppm based on the total weight of the zinc.
8. The cell according to claim 1 , wherein the sulfotricarballylate is present in an amount from 10 to 40 ppm based on the total weight of the zinc.
9. The cell according to claim 1 , wherein the positive electrode comprises manganese dioxide.
10. The cell according to claim 1 , wherein the positive electrode is an air electrode.
11. The cell according to claim 4 , wherein each of said fluorinated end groups comprises F 3 C(CF 2 ) 2 .
12. The cell according to claim 4 , wherein each of said fluorinated end groups comprises F 3 C(CF 2 ).
13. An alkaline electrochemical cell, comprising:
a container, an electrode assembly disposed within the container and comprising a negative electrode, a positive electrode, a separator located between the negative electrode and the positive electrode, and an alkaline electrolyte, wherein the negative electrode comprises zinc and a fluorosurfactant, wherein said fluorosurfactant has more than one fluorinated end group;
and wherein the fluorosurfactant forms at least one monolayer on the surface of said zinc.
14. The cell according to claim 13 , wherein said fluorosurfactant has three fluorinated end groups.
15. The cell according to claim 13 , wherein said fluorosurfactant further has an anionic polar group.
16. The cell according to claim 13 , wherein said fluorinated end groups are identical.
17. The cell according to claim 13 , wherein said fluorosurfactant is of the formula
where the groups Z 1 , Z 2 , and Z 3 are, independently of one another, branched or unbranched alkyl groups or groups of the structure R i (A(CR 1 R 2 ) ci —(CR 3 R 4 ) c′i ) di —, where the respective indices ci and c′i are, independently of one another, 0-10, and di=0-5, where R i is a branched or unbranched, fluorine-containing alkyl radical, R 1 to R 4 are, independently of one another, hydrogen or a branched or unbranched alkyl group, ci and c′i are not simultaneously 0, and A=O, S and/or N, Y 1 is an anionic polar group and Y 2 is a hydrogen atom, or vice versa, X is a cation, and at least one of the groups Z 1 , Z 2 , and Z 3 is a group of the structure R i (A(CR 1 R 2 ) ci —(CR 3 R 4 ) c′i ) di —.
18. The cell according to claim 15 , wherein said anionic polar group is a sulfonate group.
19. The cell according to claim 10 , wherein the concentration of the surfactant is 10-1000 parts per million based on the total weight of the zinc.
20. The cell according to claim 13 , wherein said fluorosurfactant has a molecular weight of between 800 and 1320.
21. The cell according to claim 1 , wherein the sulfotricarballylate is characterized by the formula
and where Z 1 ═Z 2 ═Z 3 ═F 3 C(CF 2 )(CH 2 )(O(CH 2 CH 2 CH 2 CH 2 )).