Process for forming a battery containing an iron electrode
Provided is a process for activating a battery comprising an iron electrode. The process comprises providing a battery comprising a cathode and an iron anode. The battery further comprises an electrolyte comprising NaOH, LiOH and a sulfide. The battery is then cycled to equalize the state-of-charge of the cathode and iron anode.
1. A process for activating a battery comprising an iron electrode, comprising steps of:
(i) providing a battery comprising a cathode and an iron anode, with the battery further comprising an electrolyte comprising NaOH, LiOH and a sulfide; and
(ii) cycling the battery to equalize state-of-charge of the cathode and the iron anode.
2. The process of claim 1 , wherein the battery comprises a nickel cathode.
3. The process of claim 1 , wherein the sulfide is a metal sulfide.
4. The process of claim 3 , wherein the metal sulfide is an alkali metal sulfide.
5. The process of claim 4 , wherein the metal sulfide is sodium sulfide.
6. The process of claim 1 , wherein the NaOH has a concentration in the range of 5 to 7.5 M in the electrolyte.
7. The process of claim 1 , wherein cells of the battery are initially charged between the C/2 and 2 charge rate until a cell of the battery is charged between 100 to 250% of its rated capacity.
8. The process of claim 7 where the charge rate is about 1 C.
9. The process of claim 7 where the cells are further conditioned by cycling an additional one to ten cycles.
10. The process of claim 9 where charge in an additional cycling is at the C/4 to 1 C charge rate until the cell is charged at least 120 to 200% of its rated capacity.
11. The process of claim 10 where the charge rate is about C/2.
12. The process of claim 1 wherein a first discharge is at the C/5 to C/20 discharge rate to a voltage between 1.1 to 0.9 V.
13. The process of claim 12 where the first discharge is about C/10.
14. The process of claim 12 where discharge is at the C to C/20 discharge rate until the cell voltage reaches between 1.1 to 0.9 V.
15. The process of claim 14 where the discharge rate is about C/10.
16. The process of claim 1 , wherein the NaOH concentration in the electrolyte is about 6 M, the LiOH concentration in the electrolyte is about 1 M, and sulfide concentration in the electrolyte is about 1 wt %.
17. The process of claim 1 , wherein the iron anode comprises a single substrate coated on at least one side with an iron active material composition comprising a binder.
18. The process of claim 17 , wherein the binder comprises polyvinyl alcohol.
19. The process of claim 17 , wherein the iron anode further comprises a sulfur-containing compound.
20. A battery comprising an iron electrode formed by the process of claim 1 .