Polyalkoxysiloxane catholytes for high voltage lithium batteries
Synthesis and electrochemical properties of a new class of low-glass-transition-temperature electrochemical cell polymers based on polyalkoxysiloxanes is described. Unlike ethyleneoxide (EO)-based polymers, these materials are oxidatively stable above 4.2 V, the operating voltage of high energy cells that use cathode materials such as nickel cobalt aluminum oxide (NCA) and nickel cobalt manganese oxide (NCM). Use of these electrochemical cell polymers as catholyte alternatives to PEO in high voltage cells is described.
1. A polymer composition, comprising:
an ordered nanostructure comprising a matrix of:
first domains formed by an association of first polymers; and
second domains formed by an association of second polymers;
wherein the first polymers and the second polymers form block copolymers, wherein the first polymers form first blocks and the second polymers form second blocks; and
wherein the first blocks comprise one or more polyalkoxysiloxane polymers comprising:
wherein R is selected from the group consisting of alkanes, cyclic alkanes, alkenes, cyclic alkenes, aromatics, and substituted aromatics;
R 1 is selected from the group consisting of —CN, —SO 3 − M + , —PO 4 − M + , CO 2 − M + , —N(R) 3 + X − , linear carbonates, linear phosphonates, linear phosphates, sulfonates, and cyclic carbamates;
X − is selected from the group consisting of TFSI, BF 4 − , PF 6 − , BOB − , FAP − , BETI − , and TCB − ;
M+ is an alkali or alkaline metal ion; and
v ranges from 1 to 100; and
wherein the second blocks comprise polystyrene.
2. An electrochemical cell, comprising:
an anode configured to absorb and release lithium ions;
a cathode comprising cathode active material particles, an electronically-conductive additive, a first catholyte, and an optional binder material;
a current collector adjacent to an outside surface of the cathode; and
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;
wherein the first catholyte comprises a first polyalkoxysiloxane polymer, comprising:
wherein R is selected from the group consisting of alkanes, cyclic alkanes, alkenes, cyclic alkenes, aromatics, and substituted aromatics;
R 1 is selected from the group consisting of —CN, —SO 3 − M + , —PO 4 − M + , CO 2 − M + , —N(R) 3 + X − , linear carbonates, linear phosphonates, linear phosphates, sulfonates, and cyclic carbamates;
X − is selected from the group consisting of TFSI, BF 4 − , PF 6 − , BOB − , FAP − BETI − , and TCB − ;
M+ is an alkali or alkaline metal ion; and
y ranges from 1 to 100.
3. The electrochemical cell of claim 2 wherein the first catholyte and the separator electrolyte are the same.
4. The electrochemical cell of claim 2 further comprising an overlayer between the cathode and the separator region, the overlayer comprising a second catholyte, the second catholyte comprising a second polyalkoxysiloxane polymer comprising:
wherein R is selected from the group consisting of alkanes, cyclic alkanes, alkenes, cyclic alkenes, aromatics, and substituted aromatics;
R 1 is an aprotic polar group; and
y ranges from 1 to 100.
5. The electrochemical cell of claim 4 wherein the first catholyte and the second catholyte are the same.
6. The electrochemical cell of claim 2 wherein the first catholyte further comprises:
an ordered nanostructure comprising a matrix of:
first domains defined by association of the first polyalkoxysiloxane polymers and an electrolyte salt; and
second domains defined by association of second polymers;
wherein the first polyalkoxysiloxane polymers and the second polymers form block copolymers, wherein the first polyalkoxysiloxane polymers form first blocks and the second polymers form second blocks.
7. The electrochemical cell of claim 6 wherein the second block comprises one or more polymers selected from the group consisting of polystyrene, hydrogenated polystyrene, polymethacrylate, poly(methyl methacrylate), polyvinylpyridine, polyvinylcyclohexane, polyimide, polyamide, polypropylene, polyolefins, poly(t-butyl vinyl ether), poly(cyclohexyl methacrylate), poly(cyclohexyl vinyl ether), poly(t-butyl vinyl ether), polyethylene, poly(phenylene oxide), poly(2,6-dimethyl-1,4-phenylene oxide) (PXE), poly(phenylene sulfide), poly(phenylene sulfide sulfone), poly(phenylene sulfide ketone), poly(phenylene sulfide amide), polysulfone, polyvinylidene fluoride, and copolymers that contain styrene, methacrylate, or vinylpyridine.
8. The electrochemical cell of claim 2 wherein the anode comprises a material selected from the group consisting of lithium metal, lithium alloy, graphite and silicon.
9. The electrochemical cell of claim 2 wherein the cathode active material particles comprise 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.
10. The electrochemical cell of claim 2 wherein the binder material is selected from the group consisting of polyvinylidene difluoride, poly(vinylidene fluoride-co-hexafluoropropylene, polyacrylonitrile, polyacrylic acid, polyethylene oxide, carboxymethyl cellulose, styrene-butadiene rubber, and combinations thereof.
11. An electrochemical cell, comprising:
an anode configured to absorb and release lithium ions;
a cathode comprising cathode active material particles, an electronically-conductive additive, a first catholyte, and an optional binder material;
a current collector adjacent to an outside surface of the cathode; and
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;
wherein the first catholyte comprises a first polyalkoxysiloxane polymer, comprising:
wherein y ranges from 1 to 100.