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

Patent metadata

Field	Value
Publication number	US-2016141598-A1
Application number	US-201514932361-A
Country	US
Kind code	A1
Filing date	Nov 4, 2015
Priority date	Nov 14, 2014
Publication date	May 19, 2016
Grant date	—

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.

2 . The method as defined in claim 1 wherein:
the electrochemical cell is a lithium sulfur battery;
the applying of the load initiates a discharge cycle of the lithium sulfur battery; and
the applying of the load causes the organo-polysulfide or the fluorinated organo-polysulfide additive to react to form the SEI layer.

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;
the applying of the voltage initiates a charge cycle of the lithium ion battery; and
the applying of the voltage causes the organo-polysulfide or the fluorinated organo-polysulfide additive to react to form the SEI layer.

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 method further comprises applying the voltage or the load 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 method further comprises applying the voltage or the load 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 Inc

Inventors

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

Classifications

• H01M10/052

  Li-accumulators · CPC title

• C25D9/02

  with organic materials · CPC title

• H01M10/0567

  characterised by the additives · CPC title

• H01M4/0452 Primary

  from solutions · CPC title

• Y02P70/50

  Manufacturing or production processes characterised by the final manufactured product · CPC title