Active metal electrolyzer
Electro-winning of active metal (e.g., lithium) ions from a variety of sources including industrial waste, and recycled lithium and lithium-ion batteries is accomplished with an electrolyzer having a protected cathode that is stable against aggressive solvents, including water, aqueous electrolytes, acid, base, and a broad range of protic and aprotic solvents. The electrolyzer has a highly ionically conductive protective membrane adjacent to the alkali metal cathode that effectively isolates (de-couples) the alkali metal electrode from solvent, electrolyte processing and/or cathode environments, and at the same time allows ion transport in and out of these environments. Isolation of the cathode from other components of a battery cell or other electrochemical cell in this way allows the use of virtually any solvent, electrolyte and/or anode material in conjunction with the cathode. The electrolyzer can be configured and operated to claim or reclaim lithium or other active metals from such sources.
1. A method of claiming active metal from an active metal ion source, the method comprising:
providing, at the anode of an electrolytic cell, an active metal ion source in a liquid phase that is corrosive to active metal but compatible with an anode structure; and
electrolyzing the active metal ion source with the electrolytic cell to obtain the active metal at the cathode of the electrolytic cell, wherein the electrolytic cell comprises:
the cathode,
the anode structure, at the anode, comprising an electronically conductive component, an ionically conductive component, and the active metal ion source in a liquid phase, and
an ionically conductive membrane, with a first surface and a second surface, positioned between the cathode and the anode structure,
wherein the first surface comprises a material chemically compatible with the cathode and in contact with the cathode, selected from the group consisting of active metal nitrides, active metal phosphides, active metal phosphorus oxynitride glass, and a semi-permeable membrane separator impregnated with a non-aqueous liquid or gel, and
wherein the second surface comprises a material substantially impervious to and chemically compatible with the anode structure and in contact with the anode structure, selected from the group consisting of glassy or amorphous metal ion conductors, ceramic active metal ion conductors, and glass-ceramic active metal ion conductors.
2. The method of claim 1 , wherein the active metal is obtained in the solid state.
3. The method of claim 1 , wherein the active metal ion source in a liquid phase comprises an active metal salt dissolved in a solvent that is corrosive to the active metal.
4. The method of claim 3 , wherein the solvent is selected from the group consisting of water, aqueous electrolyte, acid, base, other protic and aprotic solvents, and combinations thereof.
5. The method of claim 4 , wherein the solvent is water.
6. The method of claim 4 , wherein the solvent is an aqueous electrolyte.
7. The method of claim 3 , wherein the cell is operated by applying a voltage across the electrodes causing oxidation of the active metal salt at the anode structure, active metal ion transport through the membrane to the cathode, and reduction of the active metal ions to the active metal at the cathode.
8. The method of claim 7 , wherein the method is conducted at room temperature.
9. The method of claim 7 , wherein the voltage is about 1.5 to 6 V.
10. The method of claim 7 , wherein the cathode initially comprises the active metal.
11. The method of claim 7 , wherein the cathode initially is a substrate for active metal plating.
12. The method of claim 11 , wherein the substrate comprises a current collector.
13. The method of claim 12 , wherein the substrate further comprises a wetting layer.
14. The method of claim 1 , wherein the active metal is an alkali metal.
15. The method of claim 14 , wherein the alkali metal is lithium.
16. The method of claim 1 , wherein the first surface of the ionically conductive membrane comprises a material selected from the group consisting of Li 3 N, Li 3 P, and LiPON.
17. The method of claim 1 , wherein the first surface of the ionically conductive membrane comprises a semi-permeable membrane separator impregnated with a non-aqueous liquid or gel.
18. The method of claim 17 , wherein the non-aqueous liquid or gel is a liquid selected from the group consisting of propylene carbonate (PC) and dimethoxy ether (DME).
19. The method of claim 17 , wherein the non-aqueous liquid or gel is a gel selected from the group consisting of polyethylene oxide (PEO) and polyacrylonitrile (PAN) swollen with PC or DME.
20. The method of claim 1 , wherein the active metal ion source is selected from the group consisting of industrial waste and spent battery cells.