Aluminum-based metal-air batteries
View Patent ↗Provided in one embodiment is an electrochemical cell, comprising: (i) a plurality of electrodes, comprising a fuel electrode that comprises aluminum and an air electrode that absorbs gaseous oxygen, the electrodes being operable in a discharge mode wherein the aluminum is oxidized at the fuel electrode and oxygen is reduced at the air electrode, and (ii) an ionically conductive medium, comprising an organic solvent; wherein during non-use of the cell, the organic solvent promotes formation of a protective interface between the aluminum of the fuel electrode and the ionically conductive medium, and wherein at an onset of the discharge mode, at least some of the protective interface is removed from the aluminum to thereafter permit oxidation of the aluminum during the discharge mode.
1. A method of operating an electrochemical cell, comprising: a plurality of electrodes comprising a fuel electrode that comprises aluminum and an air electrode that absorbs gaseous oxygen, and an ionically conductive medium comprising an organic solvent, the cell being operable in a discharge mode; the method comprising:
operating the cell in the discharge mode, wherein gaseous oxygen is reduced at the air electrode and the aluminum is oxidized at the fuel electrode;
wherein during non-use of the cell, the organic solvent promotes formation of a protective interface between the aluminum of the fuel electrode and the ionically conductive medium; and
wherein at an onset of the discharge mode, at least some of the protective interface is removed from the aluminum to thereafter permit oxidation of the aluminum during the discharge mode.
2. The method of claim 1 , further comprising making the ionically conductive medium by reacting an α-hydroxy-γ-butyrolactone and choline hydroxide.
3. The method of claim 1 , wherein a surface of the fuel electrode is polished.
4. The method of claim 1 , wherein the ionically conductive medium is substantially free of chloride ions.
5. The method of claim 1 , wherein the ionically conductive medium is substantially free of lithium ions.
6. The method of claim 1 , wherein the organic solvent comprises a lactone.
7. The method of claim 1 , wherein the organic solvent comprises a butyrolactone, pentanolactone, hexanolactone, octanolactone, decanolactone, or combinations thereof.
8. The method of claim 1 , wherein the ionically conductive medium further comprises a metal triflate.
9. The method of claim 1 , wherein the ionically conductive medium comprises an aluminum triflate, sodium triflate, a copper triflate, or combinations thereof.
10. The method of claim 1 , wherein the ionically conductive medium comprises a metal triflate dissolved in the organic solvent at a concentration that is less than or equal to about 1 M.
11. The method of claim 1 , wherein the ionically conductive medium comprises an ionic liquid.
12. The method of claim 1 , wherein the ionically conductive medium comprises an ionic liquid based on the organic solvent.
13. The method of claim 1 , wherein the ionically conductive medium comprises an ionic liquid based on a lactone that is selected from the group consisting of butyrolactone, pentanolactone, octanolactone, and decanolactone.
14. The method of claim 1 , wherein the ionically conductive medium comprises an ionic liquid based on a lactone that is pentanolactone.
15. The method of claim 1 , wherein the ionically conductive medium comprises an ionic liquid that is hydrophobic.
16. The method of claim 1 , wherein the ionically conductive medium comprises an ionic liquid that is aprotic.
17. The method of claim 1 , wherein the ionically conductive medium further comprises water that is less than or equal to about 10 wt %.
18. The method of claim 1 , wherein the method is carried out at room temperature.
19. The method of claim 1 , wherein substantially all of the protective layer is removed at the onset of the discharge mode.
20. The method of claim 2 , wherein the air electrode is exposed to ambient air.