PROTECTIVE COATING FOR LITHIUM-CONTAINING ELECTRODE AND METHODS OF MAKING THE SAME

• US 20190312254A1
• Filed: 04/06/2018
• Published: 10/10/2019
• Est. Priority Date: 04/06/2018
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Xiao, Xingcheng
• Granted Patent: US 10,903,478 B2
• Time in Patent Office: Days
• CPC Class Codes: H01M 10/045 Cells or batteries with folded plate-like electrodes
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 2004/021 Physical characteristics, e.g. porosity, surface area
• CPC Class Codes: H01M 2004/027 Negative electrodes
• CPC Class Codes: H01M 2220/20 Batteries in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: H01M 4/0404 by coating on electrode collectors
• CPC Class Codes: H01M 4/0423 Physical vapour deposition
• CPC Class Codes: H01M 4/0428 Chemical vapour deposition
• CPC Class Codes: H01M 4/0471 involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
• CPC Class Codes: H01M 4/134 Electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/1395 of electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/382 Lithium H01M4/405 takes precedence
• CPC Class Codes: H01M 4/623 fluorinated polymers

Abstract

A lithium-containing electrode with a protective coating and lithium-containing electrochemical cells including the same are provided herein. The protective coating has a first layer including a first fluoropolymeric matrix and Li—F compounds and a second layer including a second fluoropolymeric matrix. Methods of preparing the protective coating on the lithium-containing electrode by applying a first fluoropolymer and/or a first fluoropolymer precursor and a second fluoropolymer and/or a second fluoropolymer precursor are also provided herein.

Claims

1. A method for preparing a protective coating on a Li-containing electrode having a surface comprising Li, the method comprising:

applying a first fluoropolymer and/or a first fluoropolymer precursor to the surface of a Li-containing layer of the Li-containing electrode to form a first layer comprising a first fluoropolymeric matrix and Li—

F bonds; and

applying a second fluoropolymer and/or a second fluoropolymer precursor to the Li-containing electrode to form a second layer comprising a second fluoropolymeric matrix, wherein the second layer is adjacent to the first layer; and

wherein the first layer has a fluorine content greater than the second layer.

2. The method of claim 1, wherein the first layer has a fluorine content of about 5 at % to about 70 at %.

3. The method of claim 1, wherein the first layer has a thickness of about 1 nm to about 5 μ

m and/or the second layer has thickness of about 1 nm to about 5 μ

m.

4. The method of claim 1, wherein the first fluoropolymer and the second fluoropolymer are the same or different and/or the first fluoropolymer precursor and the second fluoropolymer precursor are the same or different.

5. The method of claim 1, wherein the first fluoropolymer and the second fluoropolymer are each selected from the group consisting of polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), perfluoroalkoxy alkane (PFA), fluorinated ethylene propylene (FEP), ethylene tetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene (ECTFE), perfluoro-elastomer (FFPM), and a combination thereof, and/or the first fluoropolymer precursor and the second fluoropolymer precursor each form a polymer selected from the group consisting of PVF, PVDF, PTFE, PCTFE, PFA, FEP, ETFE, ECTFE, FFPM, and a combination thereof.

6. The method of claim 1, wherein the first fluoropolymer is PTFE and the second fluoropolymer is PVDF.

7. The method of claim 1, wherein first fluoropolymer and/or the second fluoropolymer are applied by physical vapor deposition, chemical vapor deposition, or wet chemistry.

8. The method of claim 1, further comprising treating the Li metal electrode to remove a passivation layer present on the Li-containing layer before applying the first fluoropolymer and/or the first fluoropolymer precursor.

9. The method of claim 1, further comprising after applying the first fluoropolymer and/or the first fluoropolymer precursor and/or after applying the second fluoropolymer and/or the second fluoropolymer precursor, maintaining the Li-containing electrode at a temperature of less than or equal to about 150°

C. for up to about 24 hours.

10. A Li-containing electrode having a surface comprising Li, wherein the Li-containing electrode comprises:

a Li-containing layer;

a first layer adjacent to a surface of the Li-containing layer, wherein the first layer comprises a first fluoropolymeric matrix and Li—

F compounds; and

a second layer adjacent to the first layer, wherein the second layer comprises a second fluoropolymeric matrix and Li—

F compounds; and

wherein the first layer has a fluorine content greater than the second layer.

11. The Li-containing electrode of claim 10, wherein the first layer has a fluorine content of about 5 at % to about 70 at %.

12. The Li-containing electrode of claim 10, wherein the first layer has a thickness of about 1 nm to about 5 μ

m, and/or the second layer has thickness of about 1 nm to about 5 μ

m.

13. The Li-containing electrode of claim 10, wherein the first fluoropolymeric matrix and the second fluoropolymeric matrix are each derived from a fluoropolymer selected from the group consisting of polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), perfluoroalkoxy alkane (PFA), fluorinated ethylene propylene (FEP), ethylene tetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene (ECTFE), perfluoro-elastomer (FFPM), and a combination thereof.

14. The Li-containing electrode of claim 10, wherein the first fluoropolymeric matrix is derived from PTFE and the second fluoropolymeric matrix is derived from PVDF.

15. A Li-containing electrochemical cell comprising:

a negative electrode layer comprising a Li-containing electrode having a surface comprising Li, wherein the Li-containing electrode comprises;

a Li-containing layer;

a first layer adjacent to a surface of the Li-containing layer, wherein the first layer comprises a first fluoropolymeric matrix and Li—

F compounds; and

a second layer adjacent to the first layer, wherein the second layer comprises a second fluoropolymeric matrix and Li—

F compounds; and

wherein the first layer has a fluorine content greater than the second layer;

a positive electrode layer spaced apart from the negative electrode layer;

a porous separator disposed between confronting surfaces of the negative electrode layer and the positive electrode layer; and

a liquid electrolyte infiltrating the negative electrode layer, the positive electrode layer, and the porous separator.

16. The Li-containing electrochemical cell of claim 15, wherein the first layer has a fluorine content of about 5 at % to about 70 at %.

17. The Li-containing electrochemical cell of claim 15, wherein the first layer has a thickness of about 1 nm to about 5 μ

m, and/or the second layer has thickness of about 1 nm to about 5 μ

m.

18. The Li-containing electrochemical cell of claim 15, wherein the first fluoropolymeric matrix and the second fluoropolymeric matrix are each derived from a fluoropolymer selected from the group consisting of polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polytetrafluoro ethylene (PTFE), polychlorotrifluoroethylene (PCTFE), perfluoroalkoxy alkane (PFA), fluorinated ethylene propylene (FEP), ethylene tetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene (ECTFE), perfluoro-elastomer (FFPM), and a combination thereof.

19. The Li-containing electrochemical cell of claim 15, wherein the first fluoropolymeric matrix is derived from PTFE and the second fluoropolymeric matrix is derived from PVDF.