Polar cyclicsiloxanes as high voltage stable electrolytes for lithium batteries
Polar cyclicsiloxane materials with various functionalities are disclosed. When combined with lithium salts, such materials can be useful as electrolyte materials in lithium battery cells. They may be used alone as electrolytes or as additives in other polymer electrolytes. Various lithium battery cell configurations that can employ such polar cyclicsiloxane materials are also described.
1. An electrochemical cell, comprising:
an anode configured to absorb and release lithium ions;
a cathode comprising a positive electrode comprising a positive electrode active material and a first catholyte comprising an electrolyte material comprising a polar cyclic siloxane with the following structure:
wherein:
R is a saturated or unsaturated hydrocarbon and is selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, tertiary butyl, n-hexyl, 2-ethyl hexyl, n-octyl, vinyl, allyl, propargyl, phenyl, 4-vinylbenzene, benzyl, napthyl, and anthracyl;
P is a polar group and is selected from the group consisting of linear carbonate, cyclic carbonate, nitrile, linear sulfonyl, cyclic sulfonyl, linear sulfinyl, cyclic sulfinyl, linear phosphate, cyclic phosphate, linear phosphonate group, cyclic phosphonate group, linear carbamoyl, cyclic carbamoyl, linear urea, cyclic urea, linear thiourea, cyclic thiourea, linear thiocarbonate, cyclic thiocarbonate, linear thiocarbamoyl, cyclic thiocarbamoyl, linear phosphonothioate group, cyclic phosphonothioate group, linear phosphoramide group, cyclic phosphoramide group, malonate, ketone and lactone group;
n is any integer from 2 to 20; and
x is any integer from 1 to 10; and
an electrolyte salt; and
optional electronically-conductive additive;
a current collector adjacent to an outside surface of the cathode;
a separator region between the anode and the cathode, the separator region comprising a separator electrolyte configured to facilitate movement of lithium ions back and forth between the anode and the cathode; and
an overlayer between the cathode and the separator region, the overlayer comprising a second catholyte, the second catholyte comprising a solid polymer electrolyte, wherein the solid polymer electrolyte is different from the separator electrolyte.
2. The positive electrode of claim 1 wherein the positive electrode active material is selected from the group consisting of lithium nickel cobalt aluminum oxide and lithium nickel cobalt manganese oxide.
3. The electrochemical cell of claim 1 wherein the first catholyte further comprises a solid polymer electrolyte.
4. The electrochemical cell of claim 1 wherein the first catholyte and the separator electrolyte are the same.
5. The electrochemical cell of claim 1 wherein the separator electrolyte comprises a solid polymer electrolyte.
6. The electrochemical cell of claim 1 wherein the first catholyte and the second catholyte are the same.
7. The electrochemical cell of claim 1 wherein the anode comprises a material selected from the group consisting of lithium metal, lithium alloy, lithium titanate, graphite, and silicon.
8. The electrochemical cell of claim 1 wherein the positive electrode active material comprises one or more materials selected from the group consisting of lithium iron phosphate, nickel cobalt aluminum oxide, nickel cobalt manganese oxide, lithium manganese phosphate, lithium cobalt phosphate, lithium nickel phosphate, and lithium manganese spinel.
9. The electrochemical cell of claim 1 wherein the cathode further comprises a binder material selected from the group consisting of polyvinylidene difluoride, polyvinylidene fluoride-co-hexafluoropropylene, polyacrylonitrile, polyacrylic acid, polyethylene oxide, carboxymethyl cellulose, styrene-butadiene rubber, and combinations thereof.
10. An electrochemical cell, comprising:
an anode configured to absorb and release lithium ions;
a cathode comprising a positive electrode comprising a positive electrode active material and a first catholyte comprising an electrolyte material comprising a polar cyclic siloxane with the following structure:
wherein:
P is a polar group and is selected from the group consisting of linear carbonate, cyclic carbonate, nitrile, linear sulfonyl, cyclic sulfonyl, linear sulfinyl, cyclic sulfinyl, linear phosphate, cyclic phosphate, linear phosphonate group, cyclic phosphonate group, linear carbamoyl, cyclic carbamoyl, linear urea, cyclic urea, linear thiourea, cyclic thiourea, linear thiocarbonate, cyclic thiocarbonate, linear thiocarbamoyl, cyclic thiocarbamoyl, linear phosphonothioate group, cyclic phosphonothioate group, linear phosphoramide group, cyclic phosphoramide group, malonate, ketone and lactone group;
n is any integer from 2 to 20; and
x is any integer from 1 to 10; and
an electrolyte salt; and
optional electronically-conductive additive;
a current collector adjacent to an outside surface of the cathode;
a separator region between the anode and the cathode, the separator region comprising a separator electrolyte configured to facilitate movement of lithium ions back and forth between the anode and the cathode; and
an overlayer between the cathode and the separator region, the overlayer comprising a second catholyte, the second catholyte comprising a solid polymer electrolyte, wherein the solid polymer electrolyte is different from the separator electrolyte.
11. The electrochemical cell of claim 10 wherein the first catholyte and the second catholyte are the same.
12. The electrochemical cell of claim 10 wherein the first catholyte further comprises a solid polymer electrolyte.
13. The electrochemical cell of claim 10 wherein the first catholyte and the separator electrolyte are the same.