Nonaqueous electrolyte compositions comprising cyclic sulfates and lithium borates
Described are electrolyte compositions containing a non-fluorinated carbonate, a fluorinated solvent, a cyclic sulfate, at least one lithium borate salt selected from lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium tetrafluoroborate, or mixtures thereof, and at least one electrolyte salt. The cyclic sulfate can be represented by the formula: wherein each A is independently a hydrogen or an optionally fluorinated vinyl, allyl, acetylenic, propargyl, or C 1 -C 3 alkyl group. The electrolyte composition may further comprise a fluorinated cyclic carbonate. The electrolyte compositions are useful in electrochemical cells, such as lithium ion batteries.
1. An electrolyte composition comprising:
a) a non-fluorinated carbonate, wherein the non-fluorinated carbonate is one or more selected from a group consisting of ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, and propylene carbonate;
b) 2,2-difluoroethyl acetate;
c) ethylene sulfate, present at a percent by weight of the composition in the range of about 0.1 wt % to about 12 wt %;
d) lithium bis(oxalato)borate at a percent by weight of the composition in the range of 0.1 wt % to 5 wt; and
e) at least one electrolyte salt, wherein the at least one electrolyte salt comprises lithium hexafluorophosphate.
2. The electrolyte composition of claim 1 , further comprising a fluorinated cyclic carbonate.
3. The electrolyte composition of claim 2 , wherein the fluorinated cyclic carbonate is fluoroethylene carbonate.
4. The electrolyte composition of claim 1 , wherein the electrolyte composition comprises about 0.1 weight percent to about 12 weight percent of ethylene sulfate and about 0.1 weight percent to about 3 weight percent of lithium bis(oxalate)borate.
5. The electrolyte composition of claim 4 , further comprising about 0.5 weight percent to about 3 weight percent of a fluorinated cyclic carbonate.
6. The electrolyte composition of claim 1 , wherein the electrolyte composition comprises ethylene carbonate, 2,2-difluoroethyl acetate, ethylene sulfate, lithium bis(oxalato)borate, and further comprises fluoroethylene carbonate.
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) the electrolyte composition of claim 1 disposed in said housing and providing an ionically conductive pathway between said anode and said cathode; and
(d) a porous separator between said anode and said cathode.
8. The electrochemical cell of claim 7 , wherein said electrochemical cell is a lithium ion battery.
9. The lithium ion battery of claim 8 , wherein the anode is lithium titanate or graphite.
10. The lithium ion battery of claim 8 , wherein the cathode comprises a cathode active material exhibiting greater than 30 mAh/g, capacity in the potential range greater than 4.6 V versus a Li/Li + reference electrode.
11. The lithium ion battery of claim 8 , wherein the cathode comprises a cathode active material which is charged to a potential greater than or equal to 4.35 V versus a Li/Li + reference electrode.
12. The lithium ion battery of claim 8 , 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.
13. The lithium ion battery of claim 8 , wherein the cathode comprises Li a A 1−b ,R b D 2 , wherein: A is Ni, Co, Mn, or a combination thereof; R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, Zr, Ti, a rare earth element, or a combination thereof, D is O, F, S, P, or a combination thereof; and 0.90≤a≤1.8 and 0≤b≤0.5.
14. The lithium ion battery of claim 8 , wherein the cathode comprises a composite material represented by the structure of Formula:
x (Li 2−w A 1−v Q w+v O 3−e ).(1− x )(Li y Mn 2−z M z O 4−d )
wherein:
x is about 0.005 to about 0.1;
A comprises one or more of Mn or Ti;
Q comprises one or more of Al, Ca, Co, Cr, Cu, Fe, Ga, Mg, Nb, Ni, Ti, V, Zn, Zr or Y;
e is 0 to about 0.3;
v is 0 to about 0.5;
w is 0 to about 0.6;
M comprises one or more of Al, Ca, Co, Cr, Cu, Fe, Ga, Li, Mg, Mn, Nb, Ni, Si, Ti, V, Zn, Zr or Y;
d is 0 to about 0.5;
y is about 0 to about 1; and
z is about 0.3 to about 1; and
wherein the Li y Mn 2−z M z O 4−d component has a spinel structure and the Li 2−w O w+v A 1−v O 3−e component has a layered structure.
15. The lithium ion battery of claim 8 , wherein the cathode comprises Li a Ni b Mn c Co d R e O 2−f Z f , wherein: R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, Zr, Ti, a rare earth element, or a combination thereof, and Z is F, S, P, or a combination thereof; and 0.8≤a≤1.2, 0.1≤b≤0.5, 0.2≤c≤0.7, 0.05≤d≤0.4, 0≤e≤0.2; wherein the sum of b+c+d e is about 1; and 0≤f≤0.08.
16. An electronic device, transportation device, or telecommunications device, comprising an electrochemical cell according to claim 7 .
17. A method comprising combining:
a) a non-fluorinated carbonate, wherein the non-fluorinated carbonate is one or more selected from a group consisting of ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, and propylene carbonate;
b) 2,2-difluoroethyl acetate;
c) ethylene sulfate present at a percent by weight of the composition in the range of about 0.1 wt % to about 12 wt %;
d) lithium bis(oxalato)borate at a percent by weight of the composition in the range of 0.1 wt % to 5 wt; and
e) at least one electrolyte salt, wherein the at least one electrolyte salt comprises lithium hexafluorophosphate;
to form an electrolyte composition.