Ionically conductive clay additive for use in electrochemical cells
View Patent ↗The present disclosure relates to alkaline electrochemical cells, such as metal-air cells, which comprise a gelled anode which may or may not include mercury, comprising an ionically conductive clay additive. The ionically conductive clay additive is modified to include halogen atoms to increase the negative charge density of the additive and improve its performance in the electrochemical cell.
1. An electrochemical cell comprising a gelled anode comprising a gelling agent, an anode active material comprising zinc, and an ionically conductive clay additive that is dispersed throughout the gelled anode, wherein the ionically conductive clay additive is present in an amount of from about 0.1% (by weight anode blend) to about 3% (by weight anode blend) and wherein the ionically conductive clay additive comprises at least about 25,000 ppm of a halogen.
2. The electrochemical cell as set forth in claim 1 wherein the ionically conductive clay additive comprises at least about 100,000 ppm of a halogen.
3. The electrochemical cell as set forth in claim 1 wherein the halogen is fluorine.
4. The electrochemical cell as set forth in claim 1 wherein the halogen is chlorine.
5. The electrochemical cell as set forth in claim 1 wherein the halogen is bromine.
6. The electrochemical cell as set forth in claim 1 wherein the ionically conductive clay additive is a natural clay.
7. The electrochemical cell as set forth in claim 1 wherein the ionically conductive clay additive is a synthetic clay.
8. The electrochemical cell as set forth in claim 1 wherein the ionically conductive clay additive is selected from the group consisting of kaolinite clays, montmorillonite clays, smectite clays, illiet clays, chlorite clays, bentonite clays, hectorite clays, and combinations thereof.
9. The electrochemical cell as set forth in claim 1 wherein the anode active material comprising zinc is an amalgamated zinc composition including mercury.
10. The electrochemical cell as set forth in claim 1 wherein the anode active material comprising zinc comprises an alloy of zinc and lead.
11. The electrochemical cell as set forth in claim 9 wherein the amalgamated zinc composition comprises from about 0.5 parts mercury per 100 parts zinc to about 6.0 parts mercury per 100 parts zinc.
12. The electrochemical cell as set forth in claim 9 wherein the amalgamated zinc composition comprises about 2.4 parts mercury per 100 parts zinc.
13. The electrochemical cell as set forth in claim 9 wherein the mean particle size of the amalgamated zinc composition is from about 300 micrometers to about 320 micrometers.
14. The electrochemical cell as set forth in claim 9 herein the median particle size of the amalgamated zinc composition is from about 250 micrometers to about 260 micrometers.
15. The electrochemical cell as set forth in claim 1 wherein the gelling agent is present in an amount of from about 0.1% (by weight anode blend) to about 3% (by weight anode blend).
16. The electrochemical cell as set forth in claim 15 wherein the gelling agent is selected from the group consisting of carboxymethylcellulose, polyacrylic acid, sodium polyacrylate, and combinations thereof.
17. The electrochemical cell as set forth in claim 1 further comprising from about 0.1% (by weight anode blend) to about 2% (by weight anode blend) magnesium oxide.
18. The electrochemical cell as set forth in claim 1 wherein the gelled anode further comprises an electrolyte solution comprising water, an alkaline solution, a suspending agent, a surfactant, and zinc oxide.
19. The electrochemical cell as set forth in claim 18 wherein the surfactant is an oxazoline surfactant.
20. The electrochemical cell as set forth in claim 18 wherein the electrolyte solution comprises from about 20% (by weight) to about 50% (by weight) potassium hydroxide, about 2% (by weight) zinc oxide, about 0.1% (by weight) suspending agent, and about 0.2% (by weight) surfactant.
21. The electrochemical cell as set forth in claim 18 further comprising an electronic conducting polymer selected from the group consisting of polyaniline, polypyrrole, polyacetylene, and combinations thereof.