Fluorinated electrolyte compositions
Electrolyte compositions comprising novel fluorine-containing carboxylic acid ester solvents are described. The fluorine-containing carboxylic acid ester solvents are represented by the formula R 1 —C(O)O—R 2 , wherein R 1 is CH 3 CH 2 — and R 2 is —CH 2 CHF 2 , R 1 is CH 3 — and R 2 is —CH 2 CH 2 CHF 2 , R 1 is CH 3 CH 2 — and R 2 is —CH 2 CH 2 CHF 2 , R 1 is CHF 2 CH 2 CH 2 — and R 2 is —CH 2 CH 3 , or R 1 is CHF 2 CH 2 — and R 2 is —CH 2 CH 3 . The electrolyte compositions are useful in electrochemical cells, such as lithium ion batteries.
1. An electrolyte composition comprising (a) at least one electrolyte salt, and (b) at least one fluorine-containing carboxylic acid ester represented by the formula R 1 —C(O)O—R 2 ,
wherein
R 1 is CH 3 CH 2 — and R 2 is —CH 2 CHF 2 ,
R 1 is CH 3 — and R 2 is —CH 2 CH 2 CHF 2 ,
R 1 is CH 3 CH 2 — and R 2 is —CH 2 CH 2 CHF 2 ,
R 1 is CHF 2 CH 2 CH 2 — and R 2 is —CH 2 CH 3 , or
R 1 is CHF 2 CH 2 — and R 2 is —CH 2 CH 3 ;
wherein the fluorine-containing carboxylic acid ester is prepared with a purity level of at least about 99.9%.
2. The electrolyte composition of claim 1 , wherein the fluorine-containing carboxylic acid ester is CH 3 CH 2 —COO—CH 2 CF 2 H or CH 3 —COO—CH 2 CH 2 CF 2 H.
3. The electrolyte composition of claim 1 further comprising at least one carbonate co-solvent.
4. The electrolyte composition of claim 3 wherein the carbonate co-solvent is selected from the group consisting of ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, vinylethylene carbonate, fluoroethylene carbonate, 2,2,2-trifluoroethyl carbonate, and methyl 2,2,3,3-tetrafluoropropyl carbonate.
5. The electrolyte composition of claim 1 wherein the electrolyte salt is selected from one or more members of the group consisting of:
lithium hexafluorophosphate,
Li PF 3 (CF 2 CF 3 ) 3 ,
lithium bis(trifluoromethanesulfonyl)imide,
lithium bis (perfluoroethanesulfonyl)imide,
lithium (fluorosulfonyl) (nonafluorobutanesulfonyl)imide,
lithium bis(fluorosulfonyl)imide,
lithium tetrafluoroborate,
lithium perchlorate,
lithium hexafluoroarsenate,
lithium trifluoromethanesulfonate,
lithium tris (trifluoromethanesulfonyl)methide,
lithium bis(oxalato)borate,
lithium difluoro(oxalato)borate,
Li 2 B 12 F 12-x H x where x is equal to 0 to 8, and
a mixture of lithium fluoride and an anion receptor.
6. The electrolyte composition of claim 1 further comprising at least one film-forming additive.
7. An electrochemical cell comprising:
(a) a housing;
(b) an anode and a cathode disposed in said housing and in ionically conductive contact with one another;
(c) an electrolyte composition disposed in said housing and providing an ionically conductive pathway between said anode and said cathode, wherein the electrolyte composition comprises:
(i) at least one electrolyte salt; and
(ii) at least one fluorine-containing carboxylic acid ester represented by the formula R 1 —C(O)O—R 2 , wherein
R 1 is CH 3 CH 2 — and R 2 is —CH 2 CHF 2 ,
R 1 is CH 3 — and R 2 is —CH 2 CH 2 CH F 2 ,
R 1 is CH 3 CH 2 — and R 2 is —CH 2 CH 2 CHF 2 ,
R 1 is CHF 2 CH 2 CH 2 — and R 2 is —CH 2 CH 3 , or
R 1 is CHF 2 CH 2 — and R 2 is —CH 2 CH 3 ; and
(d) a porous separator between said anode and said cathode;
wherein the fluorine-containing carboxylic acid ester is prepared with a purity level of at least about 99.9%.
8. The electrochemical cell of claim 7 , wherein the electrolyte composition further comprises at least one carbonate co-solvent.
9. The electrochemical cell of claim 8 wherein the carbonate co-solvent is selected from the group consisting of ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, vinylethylene carbonate, fluoroethylene carbonate, 2,2,2-trifluoroethyl carbonate, and methyl 2,2,3,3-tetrafluoropropyl carbonate.
10. The electrochemical cell of claim 7 , wherein said electrochemical cell is a lithium ion battery.
11. The lithium ion battery of claim 10 , wherein the anode is lithium titanate or graphite.
12. An electronic device comprising an electrochemical cell according to claim 7 .
13. A lithium ion battery, comprising:
(a) a housing;
(b) an anode and a cathode disposed in said housing and in ionically conductive contact with one another;
(c) an electrolyte composition disposed in said housing and providing an ionically conductive pathway between said anode and said cathode, wherein the electrolyte composition comprises:
(i) at least one electrolyte salt: and
(ii) at least one fluorine-containing carboxylic acid ester represented by the formula R 1 —C(O)O—R 2 , wherein
R 1 is CH 3 CH 2 — and R 2 is —CH 2 CHF 2 ,
R 1 is CH 3 — and R 2 is —CH 2 CH 2 CH F 2 ,
R 1 is CH 3 CH 2 — and R 2 is —CH 2 CH 2 CHF 2 ,
R 1 is CHF 2 CH 2 CH 2 — and R 2 is —CH 2 CH 3 , or
R 1 is CHF 2 CH 2 — and R 2 is —CH 2 CH 3 ; and
(d) a porous separator between said anode and said cathode;
wherein the cathode comprises a lithium-containing manganese composite oxide having a spinel structure as active material, the lithium-containing manganese composite oxide being represented by the formula:
Li x Ni y M z Mn 2-y-z O 4-d ,
wherein x is 0.03 to 1.0; x changes in accordance with release and uptake of lithium ions and electrons during charge and discharge; y is 0.3 to 0.6; M comprises one or more of Cr, Fe, Co, Li, Al, Ga, Nb, Mo, Ti, Zr, Mg, Zn, V, and Cu; z is 0.01 to 0.18, and d is 0 to 0.3.
14. The lithium ion battery of claim 13 , wherein y is 0.38 to 0.48, z is 0.03 to 0.12, and d is 0 to 0.1 and wherein M is one or more of Li, Cr, Fe, Co, and Ga.