Surface modification of silicon-containing electrodes using carbon dioxide
Various implementations of a method of forming an electrochemical cell include providing a first electrode, a second electrode, a separator between the first and second electrodes, and an electrolyte in a cell container. The first electrode can include silicon-dominant electrochemically active material. The silicon-dominant electrochemically active material can include greater than 50% silicon by weight. The method can also include exposing at least a part of the electrochemical cell to CO 2 , and forming a solid electrolyte interphase (SEI) layer on the first electrode using the CO 2 .
1. An electrochemical cell comprising:
a first electrode, a second electrode, a separator between the first and second electrodes, and an electrolyte in a cell container, wherein the first electrode comprises silicon-dominant electrochemically active material, wherein the silicon-dominant electrochemically active material comprises greater than 50% silicon by weight; and
a solid electrolyte interphase (SEI) layer on the first electrode formed from exposing at least a part of the electrochemical cell to CO 2 ;
wherein the first electrode, the second electrode, and the separator are held together with a polymer adhesive on the separator in order to maintain adhesion between the first electrode, second electrode, and separator while the at least a part of the electrochemical cell is exposed to CO 2 ;
wherein the second electrode comprises nickel cobalt aluminum (NCA); and
wherein the CO 2 is produced from Li 2 CO 3 on the surface of the NCA.
2. The electrochemical cell of claim 1 , wherein the SEI layer is about 1 nm to about 20 nm thick.
3. The electrochemical cell of claim 1 , wherein forming the SEI layer occurs during lithiation.
4. The electrochemical cell of claim 1 , wherein the silicon-dominant electrochemically active material comprises silicon at about 60% to about 100% by weight.
5. The electrochemical cell of claim 4 , wherein the silicon-dominant electrochemically active material comprises silicon at about 70% to about 100% by weight.
6. The electrochemical cell of claim 1 , wherein the CO 2 is provided in the cell container.
7. The electrochemical cell of claim 6 , wherein the CO 2 is provided in an amount of about 0.01 to about 0.6 mg per mg of the silicon.
8. The electrochemical cell of claim 1 , wherein the electrolyte comprises greater than about 10% to about 90% carbonate solvent by weight.
9. The electrochemical cell of claim 1 , wherein the electrolyte comprises a cyclic carbonate solvent.
10. The electrochemical cell of claim 9 , wherein the solvent comprises fluoroethylene carbonate (FEC), difluoroethylene carbonate (F2EC), trifluoroethylene carbonate (F3EC), ethylene carbonate (EC), propylene carbonate (PC), or trifluoropropylene carbonate (TFPC), or a mixture thereof.
11. The electrochemical cell of claim 1 , wherein the electrolyte comprises a linear carbonate solvent.
12. The electrochemical cell of claim 11 , wherein the solvent comprises ethylmethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), methyl 2,2,2-trifluoroethyl carbonate (TFEMC), ethyl 2,2,2-trifluoroethyl carbonate (TFDEC), or difluoromethyl fluoromethyl carbonate (TFDMC), or a mixture thereof.
13. The electrochemical cell of claim 1 , wherein the separator comprises polyolefin, cellulose, or a combination thereof.
14. The electrochemical cell of claim 1 , wherein the adhesive comprises poly(vinylidene fluoride)/poly(methyl methacrylate) (PVDF/PMMA).
15. The electrochemical cell of claim 1 , wherein the first electrode is a self-supported film.
16. The electrochemical cell of claim 1 , wherein the first electrode comprises a Si-composite electrochemically active film.
17. An electrochemical cell comprising:
a first electrode, a second electrode, a separator between the first and second electrodes, and an electrolyte in a cell container, wherein the first electrode comprises silicon-dominant electrochemically active material, wherein the silicon-dominant electrochemically active material comprises greater than 50% silicon by weight; and
a solid electrolyte interphase (SEI) layer on the first electrode formed from exposing at least a part of the electrochemical cell to CO 2 ;
wherein the first electrode, the second electrode, and the separator are held together with a polymer adhesive on the separator in order to maintain adhesion between the first electrode, second electrode, and separator while the at least a part of the electrochemical cell is exposed to CO 2 ;
wherein the second electrode comprises nickel cobalt aluminum (NCA); and
wherein the SEI layer comprises solid carbonate on LiF particles.
18. The electrochemical cell of claim 17 , wherein the SEI layer is about 1 nm to about 20 nm thick.
19. The electrochemical cell of claim 17 , wherein forming the SEI layer occurs during lithiation.
20. The electrochemical cell of claim 17 , wherein the silicon-dominant electrochemically active material comprises silicon at about 60% to about 100% by weight.
21. The electrochemical cell of claim 20 , wherein the silicon-dominant electrochemically active material comprises silicon at about 70% to about 100% by weight.
22. The electrochemical cell of claim 17 , wherein the CO 2 is provided in the cell container.
23. The electrochemical cell of claim 22 , wherein the CO 2 is provided in an amount of about 0.01 to about 0.6 mg per mg of the silicon.
24. The electrochemical cell of claim 17 , wherein the CO 2 is provided by adding dry ice to the electrolyte.
25. The electrochemical cell of claim 24 , wherein the CO 2 is provided in an amount of about 0.01 to about 0.6 mg per mg of the silicon.
26. The electrochemical cell of claim 17 , wherein the CO 2 is dissolved in the electrolyte.
27. The electrochemical cell of claim 26 , wherein the CO 2 is dissolved in an amount of about 0.01 to about 0.6 mg per mg of the silicon.
28. The electrochemical cell of claim 17 , wherein the electrolyte comprises greater than about 10% to about 90% carbonate solvent by weight.
29. The electrochemical cell of claim 17 , wherein the electrolyte comprises a cyclic carbonate solvent.
30. The electrochemical cell of claim 29 , wherein the solvent comprises fluoroethylene carbonate (FEC), difluoroethylene carbonate (F2EC), trifluoroethylene carbonate (F3EC), ethylene carbonate (EC), propylene carbonate (PC), or trifluoropropylene carbonate (TFPC), or a mixture thereof.
31. The electrochemical cell of claim 17 , wherein the electrolyte comprises a linear carbonate solvent.
32. The electrochemical cell of claim 31 , wherein the solvent comprises ethylmethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), methyl 2,2,2-trifluoroethyl carbonate (TFEMC), ethyl 2,2,2-trifluoroethyl carbonate (TFDEC), or difluoromethyl fluoromethyl carbonate (TFDMC), or a mixture thereof.
33. The electrochemical cell of claim 17 , wherein the separator comprises polyolefin, cellulose, or a combination thereof.
34. The electrochemical cell of claim 17 , wherein the adhesive comprises poly(vinylidene fluoride)/poly(methyl methacrylate) (PVDF/PMMA).
35. The electrochemical cell of claim 17 , wherein the first electrode is a self-supported film.
36. The electrochemical cell of claim 17 , wherein the first electrode comprises a Si-composite electrochemically active film.