Electrolyte and negative electrode structure

Abstract

An example electrolyte includes a solvent, a lithium salt, and an additive selected from the group consisting of a mercaptosilane, a mercaptosiloxane, and combinations thereof. The electrolyte may be used in a method for making a solid electrolyte interface (SEI) layer on a surface of an electrode. A negative electrode structure may be formed from the method.

What is claimed is: 
     
         1 . An electrolyte, comprising:
 a solvent;   a lithium salt; and   an additive selected from the group consisting of a mercaptosilane, a mercaptosiloxane, and combinations thereof.   
     
     
         2 . The electrolyte as defined in  claim 1  wherein the mercaptosilane is selected from the group consisting of 3-mercaptopropyltrimethoxysilane, (mercaptomethyl) methyldiethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltriethoxysilanee, 11-mercaptoundecyloxytrimethylsilane, and combinations thereof. 
     
     
         3 . The electrolyte as defined in  claim 1  wherein the mercaptosiloxane is selected from the group consisting of a [4% to 6% (mercaptopropyl)methylsiloxane]-dimethylsiloxane copolymer, a [13% to 17% (mercaptopropyl)methylsiloxane]-dimethylsiloxane copolymer, a (mercaptopropyl)methylsiloxane] homopolymer, and combinations thereof. 
     
     
         4 . The electrolyte as defined in  claim 1  wherein:
 the solvent is 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 
 the lithium salt is 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  (LiF 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 , LiAsF 6 , and combinations thereof. 
 
     
     
         5 . The electrolyte as defined in  claim 1  wherein:
 the solvent is selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, methyl formate, methyl acetate, methyl propionate, γ-butyrolactone, γ-valerolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, and combinations thereof; and 
 the lithium salt is 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 , LiAsF 6 , and combinations thereof. 
 
     
     
         6 . The electrolyte as defined in  claim 1  wherein the additive is present in an amount ranging from about 1 wt % to about 10 wt % of a total wt % of the electrolyte. 
     
     
         7 . A negative electrode structure, comprising:
 a negative electrode including an active material; and   a solid electrolyte interface (SEI) layer formed on a surface of the negative electrode, the SEI layer formed from a mercaptosilane, a mercaptosiloxane, and combinations thereof.   
     
     
         8 . The negative electrode structure as defined in  claim 7  wherein the mercaptosilane is selected from the group consisting of 3-mercaptopropyltrimethoxysilane, (mercaptomethyl) methyldiethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltriethoxysilanee, 11-mercaptoundecyloxytrimethyl silane, and combinations thereof. 
     
     
         9 . The negative electrode structure as defined in  claim 7  wherein the mercaptosiloxane is selected from the group consisting of a [4% to 6% (mercaptopropyl)methylsiloxane]-dimethylsiloxane copolymer, a [13% to 17% (mercaptopropyl)methylsiloxane]-dimethylsiloxane copolymer, a (mercaptopropyl)methylsiloxane] homopolymer, and combinations thereof. 
     
     
         10 . The negative electrode structure as defined in  claim 7  wherein the active material is selected from the group consisting of graphite, silicon-based materials, and lithium-based materials. 
     
     
         11 . 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, the electrolyte including:
 a solvent; 
 a lithium salt; and 
 an additive selected from the group consisting of a mercaptosilane, a mercaptosiloxane, and combinations thereof. 
   
     
     
         12 . The method as defined in  claim 11  wherein the electrode is exposed to the electrolyte in an electrochemical cell, and wherein the method further comprises applying a voltage to the electrochemical cell.