Fluorinated ethers and the use thereof in electrolytes and batteries

Abstract

A fluorinated ether has a structure represented by Formula (I): wherein the definitions of R1-R8, a, b, and n are provided in the disclosure. An electrolyte includes at least one fluorinated ether of Formula (I). Another electrolyte contains a first fluorinated ether, wherein the first fluorinated ether has a degree of fluorination of 10% to 50%; and a second fluorinated ether different from the first fluorinated ether and having a degree of fluorination of 40% to 100%. An electrochemical cell includes an anode; a cathode; and the above-described electrolyte.

Description

FLUORINATED ETHERS AND THE USE THEREOF IN ELECTROLYTES AND BATTERIESCROSS-REFERENCE TO RELATED APPLICATIONSThis application claims priority to U.S. Application Serial No. 63 / 574,986, filed April 5, 2024 and U.S. Application Serial No. 18 / 791,988, filed August 1, 2024, the contents of both of which are incorporated herein by reference in their entirety.FIELD

[0001] The present disclosure relates generally to fluorinated ethers, and more specifically to fluorinated ethers and the use thereof in electrolytes and electrochemical cells.BACKGROUND

[0002] As lithium-ion batteries are approaching their capacity limit, advanced battery technologies are needed to fulfill the need of high energy density applications such as electric vehicles and electric aviation. Driven by the demand, advancements in battery technology continue to emerge. For example, lithium (Li) metal, having a theoretical capacity of 3860 mAh / g, and silicon-based anodes, having a capacity up to 4200 mAh / g, are under intensive research to improve on graphite as an anode material in Li-ion batteries. However, commonly used carbonate electrolytes for Li-ion batteries are not compatible with these advanced chemistries. Continuous side reactions between lithium metal or silicon anode materials, and carbonates, can lead to the formation of lithium dendrites, or anode particle pulverization, loss of active lithium reservoir, or depletion of electrolytes, reflected by low columbic efficiency (CE) or undesirable capacity decay. Thus, there remains a need for improved electrolytes that can provide improved cycling performance when used with Li metal or silicon anode materials.SUMMARY

[0003] An electrolyte includes a lithium salt; a first ether of formula 1-40:a second ether consisting of l,l,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether, wherein a volume ratio of the first ether to the second ether is 70:30 to 15:85, 70:30 to 30:70, or 70:30 to 40:60, based on a total volume of the first ether and the second ether.

[0004] An electrolyte includes: a lithium salt; a first ether of Formula 1-55 or 1-56:1-55 1-56, ; and a second ether consisting of l,l,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether, wherein a volume ratio of the first ether to the second ether is 70:30 to 20:80 or 60:40 to 40:60, based on a total volume of the first ether and the second ether.

[0005] An electrolyte includes: a lithium salt; a first ether of formula 1-63 or 1-64:1-63, or ; and a second ether consisting of l,l,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether, wherein a volume ratio of the first ether to the second ether is 70:30 to 15:85, 70:30 to 25:75, or 70:30 to 30:70, based on a total volume of the first ether and the second ether.

[0006] An electrochemical cell includes: an anode; a cathode; and the abovedescribed electrolyte.

[0007] A method of manufacturing an electrolyte includes contacting a lithium salt, a first ether and a second ether to manufacture the electrolyte.

[0008] A method of manufacturing an electrochemical cell includes: disposing separator between an anode and a cathode to form a cell stack; and contacting the cell stack with the electrolyte of claim 1 to manufacture the electrochemical cell.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The following descriptions should not be considered limiting in any way.

[0010] FIG. 1 is a graph of capacity (ampere hour, Ah) and coulombic efficiency (%) at 25°C versus cycle number when an anode-free pouch cell having the electrolyte of Ex 2 was cycled between 3 to 4.3 volts at C / 3 charge and 1 C discharge;

[0011] FIG. 2 is a graph of capacity (Ah) and coulombic efficiency (%) at 25°C versus cycle number when an anode-free pouch cell having the electrolyte of Ex 7 was cycled between 3 to 4.3 volts at C / 3 charge and 1 C discharge;

[0012] FIG. 3 is a graph of capacity (Ah) and coulombic efficiency (%) at 25°C versus cycle number when an anode-free pouch cell having the electrolyte of Ex 9 was cycled between 3 to 4.3 volts at C / 3 charge and 1 C discharge;

[0013] FIG. 4 is a graph of capacity (Ah) and coulombic efficiency (%) at 25 °C versus cycle number when an anode-free pouch cell having the electrolyte of Ex 10 was cycled between 3 to 4.3 volts at C / 3 charge and 1 C discharge;

[0014] FIG. 5 is a graph of capacity (Ah) and coulombic efficiency (%) at 25°C versus cycle number when an anode-free pouch cell having the electrolyte of Ex 11 was cycled between 3.6 to 4.3 volts at C / 3 charge and 1 C discharge;

[0015] FIG. 6 is a graph of capacity (Ah) and coulombic efficiency (%) at 25 °C versus cycle number when an anode-free pouch cell having the electrolyte of Ex 12 was cycled between 3 to 4.3 volts at C / 3 charge and 1 C discharge;

[0016] FIG. 7 is a graph of capacity (Ah) and coulombic efficiency (%) at 25 °C versus cycle number when an anode-free pouch cell having the electrolyte of Ex 13 was cycled between 3.6 to 4.3 volts at C / 3 charge and 1 C discharge;

[0017] FIG. 8 is a graph of capacity (Ah) and coulombic efficiency (%) at 25 °C versus cycle number when an anode-free pouch cell having the electrolyte of Ex 14 was cycled between 3.6 to 4.3 volts at C / 3 charge and 1 C discharge;

[0018] FIG. 9 is a graph of capacity (Ah) and coulombic efficiency (%) at 25 °C versus cycle number when an anode-free pouch cell having the electrolyte of Ex 16 was cycled between 3 to 4.3 volts at C / 3 charge and 1 C discharge;

[0019] FIG. 10 is a graph of capacity (Ah) and coulombic efficiency (%) at 25°C versus cycle number when an anode-free pouch cell having the electrolyte of Ex 20 was cycled between 3 to 4.3 volts at C / 3 charge and 1 C discharge;

[0020] FIG. 11 is a graph of capacity (Ah) and coulombic efficiency (%) at 25°C versus cycle number when an anode-free pouch cell having the electrolyte of Ex 22 was cycled between 3 to 4.3 volts at C / 3 charge and 1 C discharge;

[0021] FIG. 12 is a graph of capacity (Ah) and coulombic efficiency (%) at 25°C versus cycle number when a silicon monoxide anode pouch cell having the electrolyte of Ex 23 was cycled between 2.5 to 4.25 volts at C / 2 charge and 1 C discharge;

[0022] FIG. 13 is a graph of capacity (Ah) and coulombic efficiency (%) at 25°C versus cycle number when a silicon monoxide anode pouch cell having the electrolyte of Ex24 was cycled between 2.5 to 4.25 volts at C / 2 charge and 1 C discharge; and

[0023] FIG. 14 is a graph of capacity (Ah) and coulombic efficiency (%) at 25°C versus cycle number when a silicon monoxide anode pouch cell having the electrolyte of Ex25 was cycled between 2.5 to 4.25 volts at C / 2 charge and 1 C discharge.DETAILED DESCRIPTION

[0024] The following description is presented to enable a person of ordinary skill in the art to make and use the various embodiments. Descriptions of specific devices, techniques, and applications are provided only as examples. Various modifications to the examples described herein will be readily apparent to those of ordinary skill in the art, and the general principles defined herein may be applied to other examples and applications without departing from the spirit and scope of the various embodiments. Thus, the various embodiments are not intended to be limited to the examples described herein and shown but are to be accorded the scope consistent with the claims.

[0025] Reference to “between” two values or parameters herein includes (and describes) embodiments that include those two values or parameters per se. For example, description referring to “between x and y” includes description of “x” and “y” per se.

[0026] It is understood that aspects and variations described herein also include “consisting” and / or “consisting essentially of’ aspects and variations.

[0027] “Combinations” is inclusive of blends, mixtures, alloys, reaction products, and the like. The terms “a” and “an” and “the” do not denote a limitation of quantity and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. “Or” means “and / or” unless clearly stated otherwise. A “combination thereof’ is open and includes any combination comprising at least one of the listed components or properties optionally together with a like or equivalent component or property not listed.

[0028] “Alkyl” as used herein refers to and includes, unless otherwise stated, a saturated linear (i.e., unbranched) or branched univalent hydrocarbon chain or combination thereof, having the number of carbon atoms designated (i.e., C1-C4 means one to four carbon atoms). Examples of alkyl groups include, but are not limited to, groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, isobutyl, sec-butyl, and the like.

[0029] “Fluoroalkyl” refers to an alkyl group in which one or more hydrogen atoms have been substituted for fluorine.

[0030] “Anode-free” as used herein indicates that at manufacture the cell does not contain a anode (negative) active material on the anode current collector. For example, in an “anode-free” cell, lithium metal may be deposited on the anode current collector on a first charge to provide lithium as the anode active material.

[0031] Fluorinated diethers with a limited fluorination degree are disclosed. The fluorinated diethers can be used optionally together with a fluorinated ether with a high fluorination degree as solvents to provide electrolytes with high ionic conductivity and high electrochemical stability.

[0032] The end points of the ranges disclosed herein (e.g., ranges related to wt.%, vol.%, volume ratio, degree of fluorination, etc.) are independently combinable.Fluorinated ethers with limited degree of fluorination

[0033] As used herein, a fluorinated ether or diether with a limited degree of fluorination (also referred to as “fluorinated ether” or “first fluorinated ether” herein) has a degree of fluorination of 10% to 50%, 10% to 35%, 10% to 25%, 14% to 25%, or 14% to 20%, wherein the degree of fluorination is determined by dividing a total number of carbon atoms in the fluorinated ether, which is substituted with at least one fluoro, by a total number of carbon atoms in the fluorinated ether.

[0034] The fluorinated ether with a limited degree of fluorination can have a structure represented by Formula (I):Formula (I), wherein:Ri and R2 are each independently Ci-Cralkyl or Ci-CrHuoroalkyl. optionally Ri and R2 are each independently Ci-C2alkyl or Ci-C2fluoroalkyl;R3, R4, Rs, Re, R7, and Rs are independently chosen at each occurrence from hydrogen, fluoro, Ci-C4alkyl, and Ci-C4fluoroalkyl; a is 0 or 1 ;b is 0 or 1; and n is 1 to 4; provided that (i) when a + b =1, R3, R4, Rs, Re, R7, and Rs are all hydrogen, and Ri is a Ci-Crfluoroalkyl, R2 is not ethyl or fluoroethyl; and (ii) the fluorinated ether is notOptionally, the fluorinated ether does not have a -CF2CF3 moiety. In some embodiments, the fluorinated ether does not have a -CF2CF2- moiety. The fluorinated ether can be free of both -CF2CF3 and -CF2CF2- moieties.

[0035] The compounds of Formula (I) also include ethers in which the variables Ri- Rs. a, b, and n carry the definitions set forth below. The variable definitions can be combined in any combination that results in a stable compound. Disclosed is an aspect wherein:(a) n is 1,(b) a is 1; and b is 1,(c) a + b = 1,(d) a is 0; and b is 0,(e) At least one of R3 or R4 is fluoro,(f) At least one of R3 or R4 is Ci-C2fluoroalkyl,(g) One of R3 and R4 is Ci-C2fluoralkyl; and the other of R3 and R4 is Ci-Csalkyl,(h) R5, Re, R7, and Rs are hydrogen,(i) R3, R4, Rs, Re, R7, and Rs are hydrogen,(j) At least one of Ri or R2is methyl,(k) At least one of Ri or R2is -CH2CH2F, -CH2CHF2, -CH2CF3, or -CH2CH3,(l) a is 1, b is 1, at least one of R3 or R4 is fluoro, and Rs, Re, R7, and Rs are hydrogen,(m) a + b =1, at least one of R3 and R4 is Ci-C2fluoralkyl, and Rs, Re, R7, and Rs are hydrogen, and(n) At least one of Ri or R2is -CH2CH2F, -CH2CHF2, or -CH2CF3; and R3, R4, Rs, Re, R7, and Rs are hydrogen.

[0036] As used herein, at least one of R3 or R4 (Ri or R2) means one or both of R3 and R4 (Ri and R2) can be the designated group.

[0037] The fluorinated ether with a limited degree of fluorination can be a diether having a structure represented by Formula (II):Formula (II), wherein:Ri and R2 are each independently Ci-C2alkyl or Ci-C2fluoroalkyl;R3 is hydrogen or fluoro;R4 is hydrogen, fluoro, or Ci-C2fluoroalkyl; n is 0 or 1; provided that when n is 0 and R4 is hydrogen, at least one of Ri and R2 is Ci- C2fluoroalkyl, and wherein the fluorinated ether has a degree of fluorination of 10% to 25%, 14% to 25%, or 14% to 20%.

[0038] Optionally, the fluorinated diether of Formula (II) is not

[0039] The fluorinated diether of Formula (II) also include ethers in which the variables R1-R4 and n carry the definitions (a) to (g), as set forth below. The variable definitions can be combined in any combination that results in a stable compound. Disclosed is an aspect wherein:(a) n is i.(b) R3 is hydrogen or fluoro.(c) n is 0.(d) At least one of Ri or R2 is Ci-C2fluoroalkyl.(e) At least one of Ri or R2 is methyl.(f) At least one of Ri or R2 is ethyl.(g) R4 is fluoro, or Ci-C2fluoroalkyl.

[0040] As used herein, at least one of Ri or R2 means one or both of Ri and R2 can be the designated group.

[0041] Some examples of the compound of Formula (I) are as follows.1-110 1-111

[0042] Some preferred examples of the compound of Formula (II) are as follows:Electrolytes

[0043] The fluorinated ether with a limited degree of fluorination can be used in an electrolyte as a solvent. Accordingly, provided is an electrolyte comprising at least one fluorinated ether with a limited degree of fluorination. For example, the electrolyte can comprise a single fluorinated ether with a limited degree of fluorination or the electrolyte can comprise 2, 3, 4, or 5 fluorinated ethers, wherein at least one, at least two, at least three, at least four, or at least five fluorinated ethers are each independently a fluorinated ether with a limited degree of fluorination.

[0044] In another aspect, an electrolyte contains (i) a fluorinated ether with a limited degree of fluorination (also referred to herein as a “first fluorinated ether” for convenience), and (ii) a second fluorinated ether with a high degree of fluorination. The second fluorinated ether is different from the first fluorinated ether and can have a degree of fluorination of 40% to 100%, 45% to 100%, 48% to 100%, or 50% to 100%, wherein the degree of fluorination is determined by dividing a total number of carbon atoms in the first or second fluorinated ether which is substituted with at least one fluoro by a total number of carbon atoms in the corresponding first or second fluorinated ether. Optionally, the first fluorinated ether does not have a -CF2CF3 moiety. In some embodiments, the first fluorinated ether doesnot have a -CF2CF2- moiety. The first fluorinated ether can be free of both -CF2CF3 and - CF2CF2- moieties.

[0045] The first fluorinated ether can have a structure represented by Formula (III):Formula (III) wherein:Ri and R2 are each independently C 1 -CAalkyl or Ci-Crfluoroalkyl, optionally Ri and R2 are each independently Ci-C2alkyl or Ci-C2fluoroalkyl;R3, R4, Rs, Re, R7, and Rs are independently chosen at each occurrence from hydrogen, fluoro, Ci-Cfralkyl. and Ci-Crfluoroalkyl; a is 0 or 1 ; b is 0 or 1 ; and n is 1 to 4.

[0046] Formula (III) also includes ethers in which the variables Ri-Rs, a, b, and n carry the definitions set for below. The variable definitions can be combined in any combination that results in a stable compound. Disclosed is an aspect wherein:(a) n is i.(b) a is 1 ; and b is 1.(c) a + b = 1.(d) a is 0; and b is 0.(e) At least one of R3 or R4 is fluoro.(f) At least one of R3 or R4 is Ci-C2fluoroalkyl.(g) One of R3 and R4 is Ci-C2fluoralkyl; and the other of R3 and R4 is Ci-Csalkyl.(h) Rs, Re, R7, and Rs are hydrogen.(i) R3, R4, Rs, Re, R7, and Rs are hydrogen.(j) At least one of Ri or R2is methyl.(k) At least one of Ri or R2is -CH2CH2F, -CH2CHF2, -CH2CF3, or -CH2CH3.(l) a is 1, b is 1, at least one of R3 or R4 is fluoro, and Rs, Re, R7, and Rs are hydrogen.(m) a + b =1, at least one of R3 and R4 is Ci-C2fluoralkyl, and Rs, Re, R7, and Rs are hydrogen.(n) At least one of Ri or R2is -CH2CH2F, -CH2CHF2, or -CH2CF3; and R3, R4, Rs, Re, R7, and Rs are hydrogen.

[0047] Some examples of the compound of Formula (III) include those described herein as examples of the compound of Formula (I), and the following additional examples.

[0048] Preferably, the first fluorinated ether is the fluorinated diether of formula (II), and more preferably the specific examples of the fluorinated diether of formula (II) as disclosed herein.

[0049] The second fluorinated ether can comprise at least one of 1, 1,2,2- tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether; bis(2,2,2-trifluoroethyl) ether; 1H,1H,5H- octafluoropentyl- 1 , 1 ,2,2-tetrafluoroethylether ; 2,2,2-trifluoroethyl- 1 , 1 ,2,2-tetrafluoroethyl ether; tris(2,2,2-trifluoroethyl) orthoformate; l,l,l,2,3,3-hexafluoro-3-(2,2,2- trifluoroethoxy)propane; hexafluoroisopropyl methyl ether; or l,2-bis(l, 1,2,2- tetrafluoroethoxy)ethane. Use of combinations comprising l,l,2,2-tetrafluoroethyl-2,2,3,3- tetrafluoropropyl ether are mentioned. Also mentioned are combinations wherein the second fluorinated ether is l, l,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

[0050] As specific examples, the first fluorinated ether is at least one of:and the second fluorinated ether is at least one of l,l,2,2-tetrafluoroethyl-2,2,3,3- tetrafluoropropyl ether; bis(2,2,2-trifluoroethyl) ether; lH,lH,5H-octafluoropentyl-l,l,2,2- tetrafluoroethylether; 2,2,2-trifluoroethyl-l,l,2,2-tetrafluoroethyl ether; tris(2,2,2- trifluoroethyl) orthoformate; 1 , 1 , 1 ,2,3 ,3 -hexafluoro-3 -(2,2,2-trifluoroethoxy)propane; hexafluoroisopropyl methyl ether; or l,2-bis(l,l,2,2-tetrafluoroethoxy)ethane, preferably l,l,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether or l,2-bis(l, 1,2,2- tetrafluoroethoxy )ethane .

[0051] The first fluorinated ether and the second fluorinated ether can have a volume ratio of 1: 10 to 10: 1, 1:5 to 5: 1, 1:3 to 3: 1, 1:2 to 2: 1, or 1: 1, 7:3 to 1:4, 7:3 to 15:85, 7:3 to 3:7, 3:2 to 3:7, or 1: 1 to 3:7, or 3:7 to 4: 1, or 3:2 to 2:3, based on a total volume of the first fluorinated ether and the second fluorinated ether. As noted above, the end points of such ranges are independently combinable.

[0052] A sum of a weight of the first fluorinated ether and a weight of the second fluorinated ether can be 50 wt.% to 100 wt.%, 55 wt.% to 99 wt.%, 60 wt.% to 95 wt.%, preferably 70 wt.% to 80 wt.%, or 75 wt.% to 80 wt.%, based on a total weight of the electrolyte.

[0053] A sum of a volume of the first fluorinated ether and a volume of the second fluorinated ether can be 50 vol.% to 100 vol.%, 55 vol.% to 99 vol.%, or 60 vol.% to 95 vol.%, or 70 vol.% to 90 vol.%, based on a total volume of the electrolyte.

[0054] The electrolyte comprises at least one salt. The salt can comprise at least one of a lithium salt, a potassium salt, or a sodium salt. The salt may be an imide, a borate, an arsenate, a phosphate, a nitrate, a perchlorate, a sulfonte, or a combination thereof. For example, the electrolyte can comprise at least one of lithium bis(fluorosulfonyl)imide (LiFSI); lithium bis(trifluoromethanesulfonyl)imide (LiTFSI); lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium hexafluorophosphate (LiPFe); lithium hexafluoroarsenate (LiAsFe); lithium tetrafluoroborate (LiBF4); lithium bis(oxalato)borate (LiBOB); lithium difluoro(oxalato)borate (LiDFOB); lithium difluorophosphate (LiDFP); lithium difluoro(dioxalato)phosphate (LiDFDOP); lithium tetrafluoro(oxalato)phosphate (LiTFOP); lithium nitrate (LiNCh); lithium perchlorate (LiClO4); lithium triflate (LiTf); lithium trifluoroacetate (LiTFA); lithium 4,5-dicyano-2-(trifluoromethyl)imidazole (LiTDI); sodium hexafluorophosphate (NaPFe); sodium bis(fluorosulfonyl)imide (NaFSI); sodium bis(trifluoromethanesulfonyl)imide (NaTFSI); sodium triflate (NaTf); sodium bis(pentafluoroethanesulfonyl)imide (NaBETI); potassium hexafluorophosphate (KPFe); potassium bis(fluorosulfonyl)imide (KFSI); potassium bis(trifluoromethanesulfonyl)imide (KTFSI); potassium triflate (KTf); cesium bis(fluorosulfonyl)imide (CsFSI); cesium bis(trifluoromethanesulfonyl)imide (CsTFSI); magnesium bis(trifluoromethanesulfonyl)imide (Mg(TFSI)2); zinc bis(trifluoromethanesulfonyl)imide (Zn(TFSI)2); calcium bis(trifluoromethanesulfonyl)imide (Ca(TFSI)2); silver bis(trifluoromethanesulfonyl)imide (AgTFSI); aluminum bis(trifluoromethanesulfonyl)imide (A1(TFSI)3); or lanthanum bis(trifluoromethanesulfonyl)imide (La(TFSI)3). A combination comprising at least one of the foregoing may be used. Use of an imide, such as a lithium imide, is mentioned. The electrolyte can comprise 0. 1 wt.% to 50 wt.%, 1 wt%, to 40 wt.%, or 5 wt.% to 40 wt.% of the salt, based on a total weight of the electrolyte.

[0055] The electrolyte including at least one fluorinated ether with a limited degree of fluorination and the electrolyte including the first fluorinated ether and the second fluorinated ether can further comprise an additional compound that is not the first fluorinated ether, or the second fluorinated ether. The additional compound can comprise at least one of ethylene carbonate (EC); propylene carbonate (PC); dimethyl carbonate (DMC); diethyl carbonate (DEC); ethyl methyl carbonate (EMC); vinyl carbonate (VC); vinyl ethylene carbonate (VEC); fluoroethylene carbonate (FEC); difluoroethylene carbonate (DFEC); 3,3,3-trifluoropropylene carbonate (TFPC); succinic anhydride (SA), butyric anhydride (BA); monofluoroethyl methyl carbonate (F1EMC); difluoroethyl methyl carbonate (F2EMC); trifluoroethyl methyl carbonate (F3EMC); bis(2,2,2-trifluoroethyl) carbonate (TFEC); 1,2- dimethyoxylethane (DME); 1,3-dioxolane (DOL); 1,4-dioxane (DOX); tetrahydrofuran (THF); tetravinyl silane (TVSI); acetonitrile (AN); ethyl acetate (EA); methyl acetate (MA); methyl propanoate (MP); succinonitrile (SN); adiponitrile (ADN); 1,3,6- Hexanetricarbonitrile (HTCN); trimethyl borate (TMB); triphenyl borate (TPB); triethyl borate (TEB); tris(pentafluorophenyl)borane (TPFPB); tris(trimethylsilyl)phosphate (TTSB); tris(2,2,2-trifluoroethyl) borate (TTFEB); trimethyl phosphate (TMP); triethyl phosphate (TEP); tris(trimethylsilyl)phosphate (TTSP); tris(trimethylsilyl)phosphite (TTSPi); tris(2,2,2- trifluoroethyl) phosphate (TFEPa); tris(2,2,2-trifluoroethyl) phosphite (TFEPi); (pentafluorophenyl)diphenyl phosphine (PFPDPP); tris(pentafluorophenyl) phosphine (TPFPP); ethoxy(pentafluoro)cyclotriphosphazene; l,3,2-dioxathiolane-2,2-dioxide (DTD); 1,3-propanesultone (PS); prop-l-ene-l,3-sultone (PES); propanediol cyclic sulfate (PCS); ethylene sulfite (ES); 1,4-butane sulfone (BS); dimethyl sulfoxide (DMSO); methylene methanedisulfonate (MMDS); l,2,6-oxadithiane-2,2,6,6-tetraoxide; N,N-Dimethylformamide (DMF); gamma-butyrolactone (BL); fluorobenzene (FB); 1,2-difluorobenzene (1,2-DFB); benzotrifluoride (BTF); (trifluoromethoxy )benzene (TFMB); or dichloromethane (DCM); 1- fluoro-2-(2-methoxyethoxy)ethane ; 1 , 1 -difluoro-2-(2-methoxyethoxy)ethane ; 1,1,1 -trifluoro- 2-(2-methoxyethoxy)ethane; l-ethoxy-2-(2-fluoroethoxy)ethane; 2-(2-ethoxy ethoxy)- 1,1- difluoroethane; l,2-bis(2-fluoroethoxy)ethane; 1, l-difluoro-2-(2-(2- fluoroethoxy)ethoxy)ethane; 1, 1, l-trifluoro-2-(2-(2-fluoroethoxy)ethoxy)ethane; 2-(2- ethoxy ethoxy)- 1,1,1 -trifluoroethane ; 1 ,2-bis(2,2-difluoroethoxy)ethane; 2-(2-(2,2- difluoroethoxy)ethoxy)-l, l,l-trifluoroethane; or l,2-bis(2,2,2-trifluoroethoxy)ethane. A combination comprising at least one of the foregoing may be used.

[0056] In some embodiments, the electrolyte does not contain the additional compound, for example the electrolyte can be free of a carbonate, e.g., contain 0 wt.% to 10 wt.%, 0. 1 wt.% to 5 wt.% or 1 wt.% to 4 wt.% of a carbonate. In other embodiments, the electrolyte contains an additional compound as described herein, and the proportion of all the fluorinated ethers in the electrolyte can be between 0.5 wt.% and 99.5 wt.%, based on a total weight of the electrolyte. Specifically, the electrolyte can contain an additional compound as described herein, and the proportion of all the fluorinated ethers in the electrolyte can be 0.5 wt.%, 1 wt.%, 5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%, 25 wt.%, 30 wt.%, 35 wt.%, 40 wt.%, 45 wt.%, 50 wt.%, 55 wt.%, 60 wt.%, 65 wt.%, 70 wt.%, 75 wt.%, 80 wt.%, 85 wt.%, 90 wt.%,95 wt.%, 99 wt.%, or 99.5 wt.% or a range between any two of the preceding values. In some embodiments, the proportion of all the fluorinated ethers in the electrolyte is at least 1 wt.%, at least 2 wt.%, at least 3 wt.%, at least 4 wt.%, at least 5 wt.%, at least 10 wt.%, at least 15 wt.%, at least 20 wt.%, at least 25 wt.%, at least 30 wt.%, at least 35 wt.%, at least 40 wt.%, at least 45 wt.%, at least 50 wt.%, at least 55 wt.%, at least 60 wt.%, at least 65 wt.%, at least 70 wt.%, at least 75 wt.%, at least 80 wt.%, at least 85 wt.%, at least 90 wt.%, at least 95 wt.%, at least 98 wt.%, or at least 99 wt.%, of the electrolyte. Preferably, the proportion of all the fluorinated ethers in the electrolyte is 60 wt.% to 95 wt.%, preferably 70 wt.% to 80 wt.% or 75 wt.% to 80 wt.%, based on a total weight of the electrolyte. Each of the fluorinated ether in the electrolyte can be present in a proportion that is independently selected from between 0.5 wt.% and 99.5 wt.%, or 10 wt.% to 70 wt.%, provided that the total amount of all fluorinated ether components in the electrolyte does not exceed 100 wt.%.

[0057] A content of the additional compound, if present, can be 0.01 wt.% to 20 wt.%, 0.01 to 15 wt.%, or 0.01 wt.% to 10 wt.%, based on a total weight of the electrolyte. A content of the additional compound can be 0.5 vol.% to 20 vol.%, 0.5 vol.% to 15 vol.%, or 0.5 vol.% to 10 vol.%, based on a total volume of the electrolyte.

[0058] In some embodiments, the electrolyte comprises the fluorinated ether with a limited degree of fluorination or a combination of the first fluorinated ether and the second fluorinated ether of any of the foregoing embodiments, and a salt of any of the foregoing embodiments (e.g., a lithium salt). As an example, the electrolyte comprises at least one fluorinated ether of Formula (I), or a combination of the first fluorinated ether and the second fluorinated ether, and the additional compound of the foregoing embodiments, and a salt of any of the foregoing embodiments (e.g., lithium salt). An amount of all the fluorinated ethers or a sum of the amounts of all the fluorinated ethers and the additional compound in the electrolyte can be at least 60 wt.% of a total weight of the electrolyte, such as at least 65 wt.%, at least 70 wt.%, at least 75 wt.%, or at least 80 wt.%, and at most 99 wt.%, at most 95 wt.%, or at most 90. wt.%, based on the total weight of the electrolyte. As noted herein, the end points of such ranges are independently combinable.

[0059] The electrolyte can consist essentially of, or consists of (i) at least one of the fluorinated ether of Formula (I) or (II), or a combination of the first fluorinated ether and the second fluorinated ether; (ii) optionally at least one of the additional compound; and (iii) the salt (e.g., lithium salt). In some embodiments, the electrolyte comprises, consists essentially of, or consists of (i) at least one of the fluorinated ether of Formula (I), or (II), or a combination of the first fluorinated ether and the second fluorinated ether; (ii) at least one ofthe additional compound such as ethers or carbonates; and (iii) the salt (e.g., lithium salt). Examples of the salt include those elaborated above.

[0060] As another example, an electrolyte (also referred to as “a preferred electrolyte example”) comprises, consisting essentially of, or consists of a first fluorinated ether, a second fluorinated ether, a salt, preferably a lithium salt, more preferably lithium bis(fluorosulfonyl)imide, optionally at a concentration of 0.5 molar (M) to 5 M, or 1 M to 3 M, and optionally 0. 1 to 30 wt.%, 0.5 wt.% to 20 wt.%, or 0.5 wt.% to 15 wt.% of an additional compound based on a total weight of the electrolyte, wherein the first fluorinated ether is at least one of:the second fluorinated ether is l,l,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether or 1,2- bis(l,l,2,2-tetrafluoroethoxy)ethane, the first fluorinated diether and the second fluorinated ether have a volume ratio of 7:3 to 3:7, 6:4 to 3:7, or 1: 1 to 3:7, or a sum of a weight of the first fluorinated diether and a weight of the second fluorinated ether is 60 wt.% to 95 wt.%, 60 wt.% to 90 wt.%, 70 wt.% to 80 wt.%, or 75 wt.% to 80 wt.%, based on a total weight of the electrolyte, and the salt comprises a lithium salt, and the additional compound, if present, can be at least one of ethylene carbonate; propylene carbonate; dimethyl carbonate; diethyl carbonate; ethyl methyl carbonate; vinyl carbonate; vinyl ethylene carbonate; fluoroethylene carbonate; difluoroethylene carbonate; 3, 3, 3 -trifluoropropylene carbonate; succinic anhydride, butyric anhydride; monofluoroethyl methyl carbonate; difluoroethyl methyl carbonate; trifluoroethyl methyl carbonate; bis(2,2,2-trifluoroethyl) carbonate; 1,2- dimethyoxylethane; 1,2-diethyoxyl ethane; 1,3-dioxolane; 1,4-dioxane; tetrahydrofuran; tetravinyl silane; acetonitrile; ethyl acetate; methyl acetate; methyl propanoate; ethylpropanoate; propyl propanoate; succinonitrile; adiponitrile; 1,3,6-Hexanetricarbonitrile; trimethyl borate; triphenyl borate; triethyl borate; tris(pentafluorophenyl)borane; tris(trimethylsilyl)phosphate; tris(2,2,2-trifluoroethyl) borate; trimethyl phosphate; triethyl phosphate; tris(trimethylsilyl)phosphate; tris(trimethylsilyl)phosphite; tris(2,2,2- trifluoroethyl) phosphate; tris(2,2,2-trifluoroethyl) phosphite; (pentafluorophenyl)diphenyl phosphine; tris(pentafluorophenyl) phosphine; ethoxy(pentafluoro)cyclotriphosphazene; l,3,2-dioxathiolane-2,2-dioxide; 1,3-propanesultone; prop-l-ene-l,3-sultone; propanediol cyclic sulfate; ethylene sulfite; 1,4-butane sulfone; dimethyl sulfoxide; methylene methanedisulfonate; l,2,6-oxadithiane-2,2,6,6-tetraoxide; N,N-Dimethylformamide; gammabutyrolactone; fluorobenzene; 1,2-difluorobenzene; benzotrifluoride;(trifluoromethoxy)benzene; dichloromethane; l-fhioro-2-(2-methoxyethoxy)ethane; 1,1- difluoro-2-(2 -methoxy ethoxy )ethane; 1, 1, l-trifluoro-2-(2-methoxyethoxy)ethane; 1 -ethoxy - 2-(2-fluoroethoxy)ethane; 2-(2-ethoxyethoxy)- 1,1 -difluoroethane; l,2-bis(2- fluoroethoxy)ethane; l,l-difluoro-2-(2-(2-fluoroethoxy)ethoxy)ethane; l,l,l-trifluoro-2-(2- (2-fluoroethoxy)ethoxy)ethane; 2-(2-ethoxyethoxy)-l,l,l-trifluoroethane; l,2-bis(2,2- difluoroethoxy)ethane; 2-(2-(2,2-difluoroethoxy)ethoxy)-l,l,l-trifluoroethane; l,2-bis(2,2,2- trifluoroethoxy)ethane; lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium hexafluorophosphate (LiPFe), lithium hexafluoroarsenate (LiAsFe), lithium tetrafluoroborate (LiBF4), lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB), lithium difluorophosphate (LiDFP), lithium difluoro(dioxalato)phosphate (LiDFDOP), lithium tetrafluoro(oxalato)phosphate (LiTFOP), lithium nitrate (LiNCh), lithium perchlorate (LiClCh), lithium tritiate (LiTf), lithium trifluoroacetate (LiTFA), lithium 4,5-dicyano-2-(trifluoromethyl)imidazole (LiTDI), sodium hexafluorophosphate (NaPFe), sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), sodium tritiate (NaTf), potassium hexafluorophosphate (KPFe), potassium bis(fluorosulfonyl)imide (KFSI), potassium bis(trifluoromethanesulfonyl)imide (KTFSI), potassium tritiate (KTf), cesium bis(fluorosulfonyl)imide (CsFSI), cesium bis(trifluoromethanesulfonyl)imide (CsTFSI), magnesium bis(trifluoromethanesulfonyl)imide (Mg(TFSI)2), zinc bis(trifluoromethanesulfonyl)imide (Zn(TFSI)2), calcium bis(trifluoromethanesulfonyl)imide (Ca(TFSI)2), silver bis(trifluoromethanesulfonyl)imide (AgTFSI), aluminum bis(trifluoromethanesulfonyl)imide (A1(TFSI)3), or lanthanumbis(trifluoromethanesulfonyl)imide (La(TFSI)3). A combination comprising at least one of the foregoing additional compounds may be used.

[0061] Preferably, the electrolyte does not undergo oxidation below a potential of 6V vs. Li+ / Li. Each of the one or more fluorinated ether having a limited degree of fluorination or the first fluorinated ether can have a first oxidation potential that is greater than 6V vs. Li+ / Li. The electrolyte may not undergo reduction above a potential of 0V vs. Li+ / Li. Each of the fluorinated ether having a limited degree of fluorination or the first fluorinated ether can have a first reduction potential that is more negative than 0V vs. Li+ / Li. The electrolyte can also have an electrochemical stability window of at least 0 V to 6V vs. Li+ / Li. The fluorinated ether having a limited degree of fluorination or the first fluorinated ether can have a collective electrochemical stability window of at least 0V to 6V vs. Li+ / Li. Each of the fluorinated ether having a limited degree of fluorination or the first fluorinated ether can have an electrochemical stability window of at least 0V to 6V vs. Li+ / Li.

[0062] The electrolyte can be prepared by combining at least a fluorinated ether of Formula (I) or (II) with at least one salt. The electrolyte can also be prepared by combining a first fluorinated ether, a second fluorinated ether, and at least one salt.Electrochemical Cell

[0063] The electrolyte as described herein can be used in an electrochemical cell. Such an electrochemical cell comprises an anode, a cathode, and an electrolyte as described herein. The electrochemical cell can also comprise a separator between the cathode and the anode. The electrochemical cell can be a battery. A method of preparing the electrochemical cell comprises providing an electrolyte as described herein; and adding the electrolyte to an assembly comprising a cathode and an anode, to manufacture the electrochemical cell.

[0064] The anode can comprise a current collector (also referred to as an “anode current collector”). Examples of metals that can be used for the current collector include, but are not limited to, copper, aluminum, lithium, sodium, potassium, magnesium, stainless steel, or an alloy containing such metals(s), among others. In some embodiments, the anode comprises (optionally solely) the anode current collector, and the electrochemical cell is an anode-free lithium, sodium, or potassium battery. Optionally, the anode does not comprise an anode active material on the anode current collector.

[0065] Alternatively, the anode of the electrochemical cell comprises an element which is at least one of lithium, sodium, or potassium. For example, the anode comprises lithium metal.

[0066] The anode can comprise at least one of lithium metal, graphite, graphene, expanded graphite, hard carbon, silicon, silicon deposited on carbon, silicon monoxide, a graphite-silicon composite, a graphite-silicon monoxide composite, a graphite-silicon nitride composite, a graphite-silicon carbide composite, lithium titanate, titanium dioxide, sodium titanate, a transition metal oxide, tin, antimony, molybdenum disulfide, a nickel- containing sulfide, sodium titanium phosphate, a MXene, sodium metal, or potassium metal. A combination comprising at least one of the foregoing may be used.

[0067] The cathode can comprise at least one of sulfur, a lithium nickel manganese cobalt oxide (NMC), a layered lithium nickel manganese oxide (NM), a lithium nickel cobalt aluminum oxide (NCA), a lithium nickel manganese aluminum oxide (NMA), a lithium nickel manganese cobalt aluminum oxide (NMC A), a lithium nickel oxide (LNO), a spinel lithium nickel manganese oxide (LiNio.5Mn1.5O4), a lithium cobalt oxide (LCO), a lithium manganese oxide (LMO), a lithium and manganese rich cathode (LMR or LLMO), a lithium iron phosphate (LFP), a lithium cobalt phosphate (LCP), a lithium manganese phosphate (LMP), a lithium manganese iron phosphate (LMFP), a transition metal sulfide, a transition metal fluoride, a sodium cobalt oxide, a sodium chromium oxide, a sodium manganese oxide, a sodium nickel manganese oxide, a sodium vanadium oxide, a sodium iron phosphate (NaFePCh), a sodium vanadium phosphate (Na3V2(PO4)3), a sodium vanadium fluorophosphate (NaVPCLF), a sodium copper nickel iron manganese oxide (Na[Cui / 9Ni2 / 9Fei / 3Mni / 3]O2), a Prussian blue (NaFe[Fe(CN)e]), or a Prussian white (R- Nai.92Fe[Fe(CN)6]). The cathode can further comprise at least one of Li, Ni, Co, Al, Fe, Zn, Cu, Mn, Mg, Ca, Ti, Zr, or V. A combination comprising at least one of the foregoing cathode materials, e.g., at least one oxide or phosphate, may be used.

[0068] Without wishing to be bound by theory, it is believed that the fluorinated ether having limited degree of fluorination or the first fluorinated ether may suppress or mitigate the formation of undesirable morphologies at the anode or cathode. For example, the fluorinated ether having limited degree of fluorination or the first fluorinated ether may suppress the formation of dendrites or the pulverization at the anode. When the anode comprises lithium metal, the fluorinated ether having limited degree of fluorination or the first fluorinated ether may suppress the formation of lithium dendrites at the anode.

[0069] An electrochemical cell (i.e. a battery) can include (1) an anode including an anode current collector, (2) a cathode including a cathode current collector and a cathode active material disposed on the cathode current collector, and (3) an electrolyte as described herein disposed between the anode and the cathode. The anode can further include an anodeactive material disposed on the anode current collector. The anode active material can comprise at least one of lithium metal, graphite, graphene, expanded graphite, hard carbon, silicon, silicon deposited on carbon, silicon monoxide, a graphite / silicon composite such as a composite of graphite and Si, SiOx, SiC, or SisN4, sodium metal, hard carbon, lithium titanate (LTO), titanium dioxide (TiCL), sodium titanate (i.e. Na-Ti-0 composites), a transition metal oxide, tin, antimony, molybdenum disulfide (M0S2), a nickel-based sulfide, a sodium titanium phosphate (NaTi2(PC>4)3), a MXene, sodium metal, or potassium metal, where silicon monoxide is specifically mentioned. The graphite / silicon composite anode active material can include graphite: silicon at a weight ratio of 5:95, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 20:80, 90: 10, or 95:5, based on a total weight of the anode active material. The cathode active material can comprise at least one of a sulfur-based cathode or an air cathode (e.g., a Li-S, Li-SPAN, or a Li-air battery), a lithium nickel manganese cobalt oxide (NMC, e.g., NMC111, NMC532, NMC622, NMC811, NMC900505, NMC95025025, etc.), a layered lithium nickel manganese oxide (NM), a lithium nickel cobalt aluminum oxide (NCA), a lithium nickel manganese aluminum oxide (NMA), a lithium nickel manganese cobalt aluminum oxide (NMCA), a lithium nickel oxide (LNO), a spinel lithium nickel manganese oxide (LiNio.5Mn1.5O4), a lithium cobalt oxide (LCO), a lithium manganese oxide (LMO), a lithium and manganese rich cathode (LMR or LLMO), a lithium iron phosphate (LFP), a lithium cobalt phosphate (LCP), a lithium manganese phosphate (LMP), a lithium manganese iron phosphate (LMFP), a transition metal sulfide (e.g., FeS, FeS2, CuS, M0S2, M0S3, TiS2, TiS4, etc.), a sodium vanadium oxide, a sodium iron phosphate (NaFePO4), a sodium vanadium phosphate (Na3V2(PO4)3), a sodium copper nickel iron manganese oxide (Na[Cui / 9Ni2 / 9Fei / 3Mm / 3]O2), a Prussian blue (NaFe[Fe(CN)e]), or Prussian white (R-Nai.92Fe[Fe(CN)6]). The cathode active material can further comprise at least one of Li, Ni, Co, Al, Fe, Zn, Cu, Mn, Mg, Ca, Ti, Zr, or V. A combination comprising at least one of the foregoing cathode materials, e.g., at least one oxide or phosphate, may be used.

[0070] An electrochemical cell (i.e. a battery) can comprise (1) an anode including an anode current collector but without any anode active material on the anode current collector, (2) a cathode including a cathode current collector and a cathode active material as described herein disposed on the cathode current collector, and (3) an electrolyte as described herein disposed between the anode and the cathode.

[0071] An electrochemical cell (i.e., a battery) can comprise (1) an anode comprising at least one of lithium metal, silicon, silicon deposited on carbon, silicon monoxide, a graphite-silicon composite, a graphite-silicon monoxide composite, a graphite-silicon nitridecomposite, a graphite-silicon carbide composite, (2) a cathode including a cathode current collector and a cathode active material as described herein disposed on the cathode current collector, and (3) an electrolyte as described herein (including the preferred electrolyte example as described herein) disposed between the anode and the cathode. A separator, such as a microporous polyolefin separator, maybe provided between the cathode and the anode. A cell stack can be an assembly of the anode, the separator, and the cathode.

[0072] Also disclosed is a method of manufacturing an electrolyte, the method comprising: contacting a lithium salt, a first ether and a second ether to manufacture the electrolyte.

[0073] Also disclosed is method of manufacturing an electrochemical cell, the method comprising: disposing separator between an anode and a cathode to form a cell stack; and contacting the cell stack with the electrolyte of claim 1 to manufacture the electrochemical cell.

[0074] The presently disclosed subject matter will be better understood by reference to the following Examples, which are provided as exemplary of the invention, and not by way of limitation.EXAMPLES

[0075] All the electrolytes shown in the table below contained 2 M lithium bis(fluorosulfonyl)imide (LiFSI). The electrolytes of Ex 4, Ex 10, Ex 13, and Ex 17 contained one fluorinated diether solvent. The electrolytes Ex 5, Ex 6, Ex 7, Ex 8, Ex 9, Ex 11, Ex 12, Ex 14, Ex 15, Ex 16, Ex 18, Ex 19, Ex 20, Ex 21, Ex 22, Ex 23, Ex 24 and Ex 25 further included a second fluorinated ether, namely, l,l,2,2-tetrafluoroethyl-2,2,3,3- tetrafluoropropylether (TTE), as a co-solvent. Ex 26 indicated that 2 M LiFSI is insoluble in l,2-bis(l,l,2,2-tetrafluoroethoxy)ethane, which is a fluorinated diether with higher fluorination degree (66.7%). The control electrolytes were formulated with 2 M LiFSI in nonfluorinated diethoxy ether (DEE) (Ex 1), DEE with TTE (Ex 2), and DEE with 1,2- bis(l,l,2,2-tetrafluoroethoxy)ethane (Ex 3). The structures of DEE and the fluorinated diethers used in the examples are shown below: 1

[0076] Cycle life was tested using anode-free or silicon monoxide anode pouch cells with nickel-manganese-cobalt (NMC) cathodes, carbon or silicon monoxide-coated copper current collector and ceramic-coated polyethylene (PE) separator. The anode-free pouch cells (Ex 1 to Ex 22) were cycled between 3 to 4.3 V at C / 3 charge and 1 C discharge. The silicon monoxide anode pouch cells (Ex 23 to Ex 25) were cycled between 2.5 to 4.25 V at C / 2 charge and 1 C discharge. The results are summarized in the table below. The capacity retention and coulombic efficiencies of the anode-free pouch cells containing the electrolytes of Ex 2, Ex 7, Ex 9, Ex 10, Ex 11, Ex 12, Ex 13, Ex 14, Ex 16, Ex 20 and Ex 22 are also shown in Figures 1-11. The capacity decay and Coulombic efficiencies of the silicon monoxide anode pouch cells containing the electrolytes of Ex 23, Ex 24, and Ex 25 are also shown in Figures 12-14.* Comparative examplesGr-SiC / NMC811 means that the tested pouch cell has an anode including a composite of graphite and SiC and a NMC8111 cathode.

[0077] The data shows that adding TTE to a fluorinated diether with a limited degree of fluorination slightly reduces ionic conductivity and greatly improves cycle life. Without wishing to be bound by theory, it is believed that adding TTE facilitates the formation of an anion-derived SEI (solid electrolyte interface), which is beneficial for suppressing side reactions between lithium metal and the electrolytes.

[0078] As compared to adding TTE to a nonfluorinated ether (DEE), adding TTE to a fluorinated diether with a limited degree of fluorination still lowers the conductivity but at a milder degree. In addition, using a fluorinated diether with a limited degree of fluorination with TTE can lead to much better cycle life as compared to using TTE together with DEE (comparing Ex 2 with Ex 7, 11, 14, and 20).

[0079] The data also shows that when a co-solvent with a degree of fluorination less than 70% is added to a nonfluorinated diether, the conductivity and cycle life are worse than adding TTE, which has a degree of fluorination of 80%, to a nonfluorinated ether. (Ex 3 versus Ex 2)

[0080] In addition, it has been found that when LiPFe is used instead of LiFSI in an electrolyte that includes both the fluorinated solvent 1 and the fluorinated solvent 2 as disclosed in the table, the LiPFe salt is insoluble, and there is no battery performance when such an electrolyte is included in a pouch cell.

[0081] Further, when using the electrolyte of Example 24 in a pouch cell with a pure graphite anode, the graphite cell sharply decayed within five cycles.

[0082] While embodiments have been set forth for the purpose of illustration, the foregoing descriptions should not be deemed a limitation on the scope herein. Accordingly, various modifications, adaptations, and alternatives can occur to one skilled in the art without departing from the spirit and scope herein.

Claims

CLAIMSWhat is claimed is:

1. An electrolyte comprising: a lithium salt; a first ether of formula 1-40::--40; and a second ether consisting of l,l,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether, wherein a volume ratio of the first ether to the second ether is 70:30 to 15:85, based on a total volume of the first ether and the second ether.

2. The electrolyte of claim 1, wherein the volume ratio of the first ether to the second ether is 60:40 to 30:70, based on a total volume of the first ether and the second ether.

3. The electrolyte of claim 2, wherein the volume ratio of the first ether to the second ether is 50:50 to 40:60, based on a total volume of the first ether and the second ether.

4. The electrolyte of claim 1, wherein the lithium salt is a lithium imide salt.

5. An electrolyte comprising: a lithium salt; a first ether of Formula 1-55 or 1-56:1-55 1-56, ; and a second ether consisting of l,l,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether, wherein a volume ratio of the first ether to the second ether is 70:30 to 20:80, based on a total volume of the first ether and the second ether.

6. The electrolyte of claim 5, wherein the volume ratio of the first ether to the second ether is 60:40 to 30:70, based on a total volume of the first ether and the second ether.

7. The electrolyte of claim 6, wherein the volume ratio of the first ether to the second ether is 50:50 to 40:60, based on a total volume of the first ether and the second ether.

8. The electrolyte of claim 7, wherein the first ether is according to Formula 1-55:1-559. The electrolyte of claim 7, wherein the first ether is according to Formula 1-56:i-5610. The electrolyte of claim 7, wherein the lithium salt is a lithium imide salt.

11. An electrolyte comprising: a lithium salt; a first ether of formula 1-63 or 1-64:; and a second ether consisting of l,l,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether, wherein a volume ratio of the first ether to the second ether is 70:30 to 15:85, based on a total volume of the first ether and the second ether.

12. The electrolyte of claim 11, wherein the volume ratio of the first ether to the second ether is 60:40 to 30:70, based on a total volume of the first ether and the second ether.

13. The electrolyte of claim 12, wherein the volume ratio of the first ether to the second ether is 50:50 to 40:60, based on a total volume of the first ether and the second ether.

14. The electrolyte of claim 12, wherein the first ether is according to Formula I- 63:

15. The electrolyte of claim 12, wherein the first ether is according to Formula I-63:1-6416. The electrolyte of claim 13, wherein the lithium salt is a lithium imide salt.

17. An electrochemical cell comprising: an anode; a cathode; and the electrolyte of claim 1.

18. The electrochemical cell of claim 17, wherein the anode comprises at least one of silicon, silicon deposited on carbon, silicon monoxide, a graphite-silicon composite, a graphite-silicon monoxide composite, a graphite-silicon nitride composite, or a graphite- silicon carbide composite.

19. An electrochemical cell comprising: an anode; a cathode; and the electrolyte of claim 5.

20. An electrochemical cell comprising: an anode; a cathode; and the electrolyte of claim 11.

21. A fluorinated ether of Formula (I):Formula (I) wherein:Ri and R2 are each independently Ci-C4alkyl or Ci-C4fluoroalkyl;R3, R4, Rs, Re, R7, and Rs are independently chosen at each occurrence from hydrogen, fluoro, Ci-C4alkyl, and Ci-C4fluoroalkyl;a is 0 or 1 ; b is 0 or 1; and n is 1 to 4; provided that (i) when a + b =1, R3, R4, Rs, Re, R7, and Rs are all hydrogen, and Ri is a Ci-Crfluoroalkyl, R2 is not ethyl or fluoroethyl; and (ii) the fluorinated ether is notwherein the fluorinated ether has a degree of fluorination of about 10% to about 50%, optionally about 10% to about 40%, and the degree of fluorination is determined by dividing a total number of carbon atoms substituted with one or more fluoro in the fluorinated ether by a total number of carbon atoms in the fluorinated ether.

22. An electrolyte comprising the fluorinated ether of claim 21.

23. A method of manufacturing an electrolyte, the method comprising: contacting a lithium salt, a first ether and a second ether to manufacture the electrolyte.

24. A method of manufacturing an electrochemical cell, the method comprising: disposing separator between an anode and a cathode to form a cell stack; and contacting the cell stack with the electrolyte of claim 1 to manufacture the electrochemical cell.

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