Methods for making a solid electrolyte interface layer on a surface of an electrode

Patent metadata

Field	Value
Publication number	US-9979008-B2
Application number	US-201514932361-A
Country	US
Kind code	B2
Filing date	Nov 4, 2015
Priority date	Nov 14, 2014
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

In an example of the method for making a solid electrolyte interface (SEI) layer on a surface of an electrode, the electrode is exposed to an electrolyte solution in an electrochemical cell. The electrolyte solution includes either i) an organo-polysulfide additive having a formula RS n R′ (n≥2), wherein R and R′ are independently selected from a methyl group, an unsaturated chain, a 3-(Trimethoxysilyl)-1-propyl group, or a 4-nitrophenyl group, or ii) a fluorinated organo-polysulfide additive having a formula RS n R′ (n≥2), wherein R and R′ can be the same or different, and wherein R and R′ each have a general formula of C x H y F (2x−y+1) , where x is at least 1 and y ranges from 0 to 2x. A voltage or a load is applied to the electrochemical cell.

First claim

What is claimed is:

1. A method for making a solid electrolyte interface (SEI) layer on a surface of an electrode, the method comprising:
exposing the electrode to an electrolyte solution in an electrochemical cell, the electrolyte solution including either i) an organo-polysulfide additive having a formula RS n R′ (n≥2), wherein R and R′ are independently selected from a methyl group, an unsaturated chain, a 3-(Trimethoxysilyl)-1-propyl group, or a 4-nitrophenyl group or ii) a fluorinated organo-polysulfide additive having a formula RS n R′ (n≥2), wherein R and R′ can be the same or different, and wherein R and R′ each have a general formula of C x H y F (2x−y+1) , where x is at least 1 and y ranges from 0 to 2x; and
applying a voltage or a load to the electrochemical cell, wherein the applying of the voltage or the load causes the organo-polysulfide additive or the fluorinated organo-polysulfide additive to react to form the SEI layer.

2. The method as defined in claim 1 wherein:
the electrochemical cell is a lithium sulfur battery; and
the applying of the load initiates a discharge cycle of the lithium sulfur battery.

3. The method as defined in claim 2 wherein:
the electrode is a sulfur-carbon composite positive electrode of the lithium sulfur battery;
the lithium sulfur battery further includes a lithium negative electrode; and
a working voltage across the load ranges from greater than 0V to about 3V.

4. The method as defined in claim 3 wherein the electrolyte solution further includes:
a solvent selected from the group consisting of 1,3-dioxolane, dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,2-diethoxyethane, ethoxymethoxyethane, tetraethylene glycol dimethyl ether (TEGDME), polyethylene glycol dimethyl ether (PEGDME), and mixtures thereof; and
a lithium salt selected from the group consisting of lithium bis(trifluoromethylsulfonyl)imide (LiN(CF 3 SO 2 ) 2 or LiTFSI), LiNO 3 , LiPF 6 , LiBF 4 , LiI, LiBr, LiSCN, LiClO 4 , LiAlCl 4 , LiB(C 2 O 4 ) 2 (LiBOB), LiB(C 6 H 5 ) 4 , LiBF 2 (C 2 O 4 ) (LiODFB), LiN(SO 2 F) 2 (LiFSI), LiPF 3 (C 2 F 5 ) 3 (LiFAP), LiPF 4 (CF 3 ) 2 , LiPF 4 (C 2 O 4 ) (LiFOP), LiPF 3 (CF 3 ) 3 , LiSO 3 CF 3 , LiCF 3 SO 3 , LiAsF 6 , and combinations thereof.

5. The method as defined in claim 4 wherein the electrolyte solution further includes a fluorinated ether selected from the group consisting of Bis(2,2,2-trifluoroethyl) ether (F 3 C—CH 2 —O—CH 2 —CF 3 ) and Propyl 1,1,2,2-tetrafluoroethyl ether (H 7 C 3 —O—CF 2 —CHF 2 ).

6. The method as defined in claim 1 wherein:
the electrochemical cell is a lithium ion battery; and
the applying of the voltage initiates a charge cycle of the lithium ion battery.

7. The method as defined in claim 6 wherein:
the electrode is a graphite negative electrode or a silicon negative electrode of the lithium ion battery;
the lithium ion battery further includes a lithium-based positive electrode; and
the applied voltage ranges from greater than 2 V to about 5 V.

8. The method as defined in claim 7 wherein the electrolyte solution further includes:
a solvent selected from the group consisting of ethylene carbonate, dimethyl carbonate, diethyl carbonate, and a mixture of ethylene carbonate, dimethyl carbonate, diethyl carbonate; and
a lithium salt selected from the group consisting of lithium bis(trifluoromethylsulfonyl)imide (LiN(CF 3 SO 2 ) 2 or LiTFSI), LiNO 3 , LiPF 6 , LiBF 4 , LiI, LiBr, LiSCN, LiClO 4 , LiAlCl 4 , LiB(C 2 O 4 ) 2 (LiBOB), LiB(C 6 H 5 ) 4 , LiBF 2 (C 2 O 4 ) (LiODFB), LiN(SO 2 F) 2 (LiFSI), LiPF 3 (C 2 F 5 ) 3 (LiFAP), LiPF 4 (CF 3 ) 2 , LiPF 4 (C 2 O 4 ) (LiFOP), LiPF 3 (CF 3 ) 3 , LiSO 3 CF 3 , LiCF 3 SO 3 , LiAsF 6 , and combinations thereof.

9. The method as defined in claim 1 wherein:
the electrode is a graphite working electrode or a silicon working electrode;
the electrochemical cell is a half cell including a lithium reference/counter electrode; and
the applied voltage ranges from greater than 0 V to about 2 V.

10. The method as defined in claim 9 , further comprising incorporating the electrode having the solid electrolyte interface (SEI) layer thereon into a lithium ion battery.

11. The method as defined in claim 1 wherein the electrolyte solution includes the organo-polysulfide, wherein the R is the unsaturated chain, the 3-(Trimethoxysilyl)-1-propyl group, or the 4-nitrophenyl group, and wherein the applying the voltage or the load occurs for a time of a charge process or discharge process of the electrochemical cell, whereby in situ polymerization of the unsaturated chain, the 3-(Trimethoxysilyl)-1-propyl group, or the 4-nitrophenyl group takes place.

12. The method as defined in claim 1 wherein the electrolyte solution includes the organo-polysulfide or the fluorinated organo-polysulfide additive in an amount ranging from greater than 0 vol % to about 50 vol % of a total vol % of the electrolyte solution.

13. The method as defined in claim 1 wherein:
the electrode is a lithium working electrode;
the electrochemical cell is a half cell including a lithium reference/counter electrode; and
the applied voltage forces a reaction between the lithium working electrode and the organo-polysulfide or the fluorinated organo-polysulfide additive to form the SEI layer.

14. The method as defined in claim 1 wherein the electrolyte solution includes the organo-polysulfide additive and the unsaturated chain is selected from the group consisting of a vinyl group and an allyl group.

15. The method as defined in claim 1 wherein the electrolyte solution includes the fluorinated organo-polysulfide and the R and R′ are independently selected from the group consisting of CF 3 , CF 2 CF 3 , and CH 2 CF 3 .

16. The method as defined in claim 1 wherein the electrolyte solution includes the fluorinated organo-polysulfide and wherein the applying the voltage or the load occurs for a time of a charge process or discharge process of the electrochemical cell, whereby in situ polymerization of any of R or R′ takes place.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Dai Fang
• Cai Mei
• Xiao Qiangfeng
• Yang Li

Classifications

• H01M4/139

  Processes of manufacture · CPC title

• H01M4/382

  Lithium (H01M4/405 takes precedence) · CPC title

• H01M4/0452 Primary

  from solutions · CPC title

• H01M10/052

  Li-accumulators · CPC title

• H01M4/362

  Composites · CPC title