Vertically integrated pure lithium metal production and lithium battery production
Methods are proposed for fabricating highly pure lithium metal electrodes from aqueous lithium salt solutions. Electrolysis is performed through lithium ion selective membranes, with constant current densities between about 10 mA/cm 2 and about 50 mA/cm 2 being applied for a time between about 1 minute and about 60 minutes. The electrolysis is performed under a blanketing atmosphere, the blanketing atmosphere being substantially free of lithium reactive components. Methods are further proposed for vertically integrating the electrolytic fabrication of highly pure lithium metal electrodes into the production of lithium metal batteries, the fabrication of lithium electrodes and lithium metal batteries being performed in a single facility.
1. A method of manufacturing a lithium electrode, comprising:
(1) providing an electrolytic cell, the electrolytic cell including:
a first chamber containing a positive electrode, and an aqueous lithium salt solution in contact with the positive electrode;
a second chamber containing a conductive substrate configured as a negative electrode, the conductive substrate being stationary in the chamber during lithium metal electrodeposition, a lithium ion selective membrane separating the first chamber from the second chamber, and a non-aqueous electrolyte disposed between the conductive substrate and the lithium ion selective membrane, physically contacting both the conductive substrate and the lithium ion selective membrane;
the electrolytic cell being configured to allow passage of lithium ions through the lithium ion selective membrane between the first and the second chambers, and to preclude passage of other chemical species between the first and the second chambers;
(2) blanketing the electrolytic cell with a blanketing atmosphere, the blanketing atmosphere being substantially free of lithium reactive components; and
(3) applying a variable voltage in order to maintain a constant current across the negative electrode and the positive electrode, thereby causing lithium ions to cross from the first chamber to the second chamber, through the lithium ion selective membrane and the non-aqueous electrolyte, and electrodeposit a first layer of lithium onto the conductive substrate, thereby forming the lithium electrode, the first layer of lithium being devoid of nanorods and having an inner face and an outer face, the inner face of the first layer of lithium bonded to the conductive substrate;
wherein the constant current is between about 10 mA/cm 2 and about 50 mA/cm 2 , and wherein the constant current is applied for a time between about 1 minute and about 60 minutes;
wherein as the first layer of lithium is formed, the first layer of lithium displaces non-aqueous electrolyte from a space between the conductive substrate and the lithium ion-selective membrane, thereby bonding the inner face of first layer of lithium to the conductive substrate and the outer face of the first layer of lithium to the ion selective membrane, thereby forming a lithium metal electrode comprising the conductive substrate and the first layer of lithium metal, with the inner face of the first layer of lithium bonded to the conductive substrate, and the outer face of the first layer of lithium bonded to the lithium ion-selective membrane, which is configured to function as a solid state electrolyte when the lithium metal electrode is incorporated into a galvanic cell.
2. The method according to claim 1 , wherein the blanketing atmosphere includes no more than 10 ppm of lithium reactive components on a molar basis.
3. The method according to claim 1 , wherein the blanketing atmosphere includes no more than 10 ppm nitrogen on a molar basis.
4. The method according to claim 1 , wherein the blanketing atmosphere includes no more than 5 ppm nitrogen on a molar basis.
5. The method according to claim 1 , wherein the conductive substrate comprises a plate having a first face and a second face, wherein the inner face of the first layer of lithium metal bonds to the first face of the conductive substrate.
6. The method according to claim 1 , wherein the aqueous lithium salt solution comprises a lithium salt selected from the group consisting of Li 2 SO 4 , Li 2 CO 3 , and combinations thereof.
7. The method according to claim 1 , wherein the aqueous lithium salt solution includes Li 2 SO 4 .
8. The method according to claim 1 , wherein the conductive substrate is selected from a group consisting of copper, aluminum, graphite coated copper, and nickel.
9. The method according to claim 1 , wherein the lithium ion selective membrane comprises a polymeric matrix and a plurality of ion-conducting particles disposed within the polymeric matrix.
10. The method according to claim 1 , wherein the lithium ion selective membrane comprises a glass frit with lithium ion conducting particles disposed within.
11. The method according to claim 1 , wherein the atmosphere comprises argon with a purity of greater than 99.998 weight percent.
12. The method according to claim 1 , wherein the lithium electrode has a specific capacity of greater than about 3800 mAh per gram of lithium.
13. A method of manufacturing a lithium metal battery, comprising:
manufacturing a lithium electrode according to the method of claim 1 ;
assembling a casing with contents including a cathode, an electrolyte, a separator and the lithium electrode configured as an anode; and
sealing the casing to isolate the contents of the casing from reactants present in air, thereby providing the lithium metal battery.
14. The method of manufacturing according to claim 13 , the method being performed in a single manufacturing facility.
15. The method according to claim 1 , wherein the lithium ion selective membrane is stationary in the electrolytic cell.
16. The method of manufacturing according to claim 1 , wherein the constant current is between about 25 mA/cm 2 and about 50 mA/cm 2 .