Synergistic additives for electrochemical cells with electrodeposited fuel
View Patent ↗An embodiment of the invention provides for an electrochemical cell comprising: a fuel electrode comprising a metal fuel, a second electrode, an ionically conductive medium communicating the electrodes, the ionically conductive medium comprising at least two different additives, wherein at least one additive is selected from the group consisting of: macroheterocyclic compounds, phosphonium salts, hetero-ionic compounds and their derivatives; and, at least one additive is selected from the group consisting of: macroheterocyclic compounds, phosphonium salts, hetero-ionic compounds, and their derivatives. The fuel electrode and the second electrode are operable in a discharge mode wherein the metal fuel is oxidized at the fuel electrode functioning as an anode, whereby electrons are generated for conduction from the fuel electrode to the second electrode via a load. An ionically conductive medium and methods of operating an electrochemical cell are also disclosed.
1. An electrochemical cell comprising:
a fuel electrode comprising a metal fuel,
a second electrode,
an ionically conductive medium communicating the electrodes, the ionically conductive medium comprising at least two different additives, wherein at least one additive is selected from the group consisting of: macroheterocyclic compounds, phosphonium salts, hetero-ionic compounds and their derivatives; and,
at least one additive is selected from the group consisting of: macroheterocyclic compounds, phosphonium salts, hetero-ionic compounds, and their derivatives;
the fuel electrode and the second electrode being operable in a discharge mode wherein the metal fuel is oxidized at the fuel electrode functioning as an anode, whereby electrons are generated for conduction from the fuel electrode to the second electrode via a load.
2. The electrochemical cell according to claim 1 is a primary battery.
3. The electrochemical cell according to claim 1 is a secondary battery.
4. The electrochemical cell according to claim 2 , further comprising a charging electrode and reducible metal fuel ions within the ionically conductive medium;
the fuel electrode and the charging electrode being operable in a charge mode wherein the reducible metal fuel ions are reduced and electrodeposited as metal fuel in oxidizable form on the fuel electrode functioning as a cathode, upon application of an electrical current between the charging electrode and the fuel electrode.
5. The electrochemical cell according to claim 2 , wherein the fuel electrode comprises a plurality of spaced apart permeable bodies for receiving a metal fuel by electrodeposition, wherein said electrodeposition causes growth among the permeable electrode bodies such that the electrodeposited metal fuel establishes an electrical connection between the permeable electrode bodies.
6. The electrochemical cell according to claim 1 , wherein the ionically conductive medium is an aqueous electrolyte solution.
7. The electrochemical cell according to claim 6 , wherein the aqueous electrolyte solution is alkaline.
8. The electrochemical cell according to claim 7 , wherein the aqueous electrolyte solution comprises potassium hydroxide.
9. The electrochemical cell according to claim 1 , wherein the macroheterocyclic compound is selected from the group of:
where X 1 -X 6 are heteroatoms each selected from nitrogen, oxygen, sulfur, phosphorous or nitrogen unsubstituted, or substituted with hydrogen, linear or branched alkyl, linear or branched alkenyl, linear or branched alkynyl, substituted or unsubstituted aryl, hydroxyl, carbonyl, carboxy, amine, amide, imine, phosphine, phosphine oxide, pyridyl, thiol sulfide, sulfoxy, halide, derivatives and combinations thereof;
each R is selected from the group consisting of hydrogen, short chain linear alkyl, and short chain branched alkyl or R 2 is ketyl.
10. The electrochemical cell according to claim 1 , wherein a macroheterocyclic compound is selected from the group of 12-crown-4; 15-crown-5; 18-crown-6; 1,4,7,10-tetraazacyclododecane; 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane; 1,4,7,10-tetrabenzyl-1,4,7,10-tetraazacyclododecane; cis-glyoxal-cyclen and derivatives thereof.
11. The electrochemical cell according to claim 1 , wherein the phosphonium salt has a structure according to:
wherein R 1 -R 4 are each selected from the group consisting of hydrogen, short chain (C 1 -C 6 ) linear alkyl, and short chain branched alkyl, cyclic alkyl, alkyl amino, pyridyl, pyrrolyl, imino, pyridinyl pyrazinyl, pyrimidinyl, thienyl, thiazolyl, furyl, pyrazolyl, imidazolyl, triazolyl, tetrazolyl, and quinolinyl, and wherein A − is an organic or inorganic anion or an equivalent of a multiply charged inorganic or organic anion.
12. The electrochemical cell according to claim 1 , wherein the phosphonium salt comprises an alkyl phosphonium cation.
13. The electrochemical cell according to claim 1 , wherein the phosphonium salt comprises an aminophosphonium cation.
14. The electrochemical cell according to claim 1 , wherein the cation of the phosphonium salt comprises a phosphazenium cation.
15. The electrochemical cell according to claim 1 , wherein the cation of the phosphonium salt is selected from the group of tetraethylphosphonium, tris(dimethylamino)(methyl)phosphonium and derivatives thereof.
16. The electrochemical cell according to claim 1 , wherein the hetero-ionic compound has a structure has a structure according to:
where A represents a charge center which may be selected from the group of: quaternary ammonium, cyclic ammonium, polycyclic ammonium, quaternary phosphonium, cyclic phosphonium, polycyclic phosphonium, phosphazine, cyclic phosphazine, polycyclic phosphazine and derivatives thereof;
where R represents an organic linkage which may be selected from the group of (C 1 -C 20 ) linear alkyl, branched alkyl, aryl, alkyl amino, pyridyl, pyrrolyl, imino, pyridinyl pyrazinyl, pyrimidinyl, thienyl, thiazolyl, and derivatives thereof;
and where B represents an aromatic group which may be selected from the group of benzene, azirine, diazirine, azete, pyrrole, imidazole, pyrazole, triazole, pyridine, pyrazine, diazine, triazine, azepine, diazepine, azocine, phosphole, phosphinine, oxazole, thiophene and derivatives thereof.
17. The electrochemical cell according to claim 1 , wherein the hetero-ionic compound has a structure according to:
where A represents a charge center which may be selected from the group of: quaternary ammonium, cyclic ammonium, polycyclic ammonium, quaternary phosphonium, cyclic phosphonium, polycyclic phosphonium, phosphazine, cyclic phosphazine, polycyclic phosphazine and derivatives thereof;
where R 1 represents branched linkage providing a β-carbon atom relative to charge center A without beta protons which may be selected from the group of: branched alkyl, aryl, neopentyl, tert-butyl alcohol, and derivatives thereof;
where R 2 represents an organic linkage comprising at least two carbon atoms which may be selected from the group of (C 1 -C 20 ) linear alkyl, branched alkyl, aryl, alkyl amino, pyridyl, pyrrolyl, imino, pyridinyl pyrazinyl, pyrimidinyl, thienyl, thiazolyl, and derivatives thereof;
and where B represents an aromatic group which may be selected from the group of benzene, azirine, diazirine, azete, pyrrole, imidazole, pyrazole, triazole, pyridine, pyrazine, diazine, triazine, azepine, diazepine, azocine, phosphole, phosphinine, oxazole, thiophene and derivatives thereof.
18. The electrochemical cell according to claim 1 , wherein the hetero-ionic compound has a structure comprising a base-stable linkage between a charge center and an aromatic group, thereby preventing reductive cleavage of the hetero-ionic compound.
19. The electrochemical cell according to claim 1 , wherein the hetero-ionic compound is a hetero-ionic aromatic compound.
20. The electrochemical cell according to claim 1 , wherein the hetero-ionic compound is selected from the group of:
and derivatives thereof.
21. The electrochemical cell according to claim 1 , wherein the hetero-ionic compound is selected from the group of 1-methyl-4-aza-1-azoniabicyclo[2,2,2]octane, 1-imidazole-4-aza-1-azoniabicyclo[2,2,2]octane and derivatives thereof.
22. The electrochemical cell according to claim 1 , wherein the macroheterocyclic compound is in a concentration of 0.0001 mol/L to 0.2 mol/L.
23. The electrochemical cell according to claim 1 , wherein the phosphonium salt is in a concentration of 0.0005 mol/L to 0.02 mol/L.
24. The electrochemical cell according to claim 1 , wherein the hetero-ionic compound is in a concentration of 0.0001 mol/L to 0.4 mol/L.
25. The electrochemical cell according to claim 1 , wherein the metal fuel is zinc.
26. The electrochemical cell according to claim 1 , wherein an additive of the at least two additives strongly adsorbs at the fuel electrode comprising the metal fuel.
27. The electrochemical cell according to claim 1 , wherein an additive of the at least two additives inhibits corrosion of the metal fuel.
28. The electrochemical cell according to claim 2 , wherein an additive of the at least two additives controls the morphology of the metal fuel electrodeposit.
29. The electrochemical cell according to claim 2 , wherein an additive of the at least two additives minimizes preferential plating of the metal fuel electrodeposit at edges or corners.
30. The electrochemical cell according to claim 1 , wherein the first electrode comprises a series of permeable bodies arranged in spaced apart relation; wherein during charging the electrochemical cell: the electrochemical current is applied between a charging electrode and at least one of the permeable electrode bodies with the charging electrode functioning as the anode and the at least one permeable electrode body functioning as the cathode, such that the reducible metal fuel ions are reduced and electrodeposited as metal fuel in oxidizable form on the at least one permeable electrode body;
said electrodeposition causing growth among the permeable electrode bodies such that the electrodeposited metal fuel establishes an electrical connection between the permeable electrode bodies.
31. The electrochemical cell according to claim 1 , wherein the metal fuel is zinc and the reducible metal fuel ions are reducible zinc ions.
32. A method of operating an electrochemical cell, wherein the cell comprises:
a fuel electrode comprising a metal fuel,
a second electrode,
an ionically conductive medium communicating the electrodes, the ionically conductive medium comprising at least two different additives,
wherein at least one additive is selected from the group consisting of: macroheterocyclic compounds, phosphonium salts, hetero-ionic compounds and their derivatives; and,
at least one additive is selected from the group consisting of: macroheterocyclic compounds, phosphonium salts, hetero-ionic compounds, and their derivatives;
wherein the method comprises discharging the electrochemical cell by:
i. oxidizing the metal fuel at the fuel electrode functioning as an anode whereby electrons are generated for conduction from the fuel electrode to the second electrode via a load; and,
ii. disconnecting the fuel electrode and the second electrode from the load to discontinue the discharging.
33. The method according to claim 32 , wherein the electrochemical cell further comprises a charging electrode and reducible metal fuel ions within the ionically conductive medium; wherein the method further comprises charging the electrochemical cell by:
i. applying an electrical current between the charging electrode and the fuel electrode functioning as the cathode, such that reducible metal fuel ions are reduced and electrodeposited as metal fuel in oxidizable form on the fuel electrode; and,
ii. removing the electrical current to discontinue the charging.
34. The method according to claim 33 , wherein the fuel electrode comprises a series of permeable bodies arranged in spaced apart relation; wherein during charging the electrochemical cell: the electrochemical current is applied between a charging electrode and at least one of the permeable electrode bodies with the charging electrode functioning as the anode and the at least one permeable electrode body functioning as the cathode, such that the reducible metal fuel ions are reduced and electrodeposited as metal fuel in oxidizable form on the at least one permeable electrode body;
said electrodeposition causing growth among the permeable electrode bodies such that the electrodeposited metal fuel establishes an electrical connection between the permeable electrode bodies.
35. An electrochemical cell according to claim 1 , wherein the ionically conductive medium contacts the fuel electrode.
36. An electrochemical cell according to claim 1 , wherein the ionically conductive medium contacts the fuel and second electrodes.
37. A method according to claim 32 , wherein the ionically conductive medium contacts the fuel electrode.
38. An electrochemical cell according to claim 32 , wherein the ionically conductive medium contacts the fuel and second electrodes.