Ion conducting polymers and polymer blends for alkali metal ion batteries
Electrolyte compositions for batteries such as lithium ion and lithium air batteries are described. In some embodiments the compositions are liquid compositions comprising (a) a homogeneous solvent system, said solvent system comprising a perfluropolyether (PFPE) and polyethylene oxide (PEO); and (b) an alkali metal salt dissolved in said solvent system. In other embodiments the compositions are solid electrolyte compositions comprising: (a) a solid polymer, said polymer comprising a crosslinked product of a crosslinkable perfluropolyether (PFPE) and a crosslinkable polyethylene oxide (PEO); and (b) an alkali metal ion salt dissolved in said polymer. Batteries containing such compositions as electrolytes are also described.
1. A liquid electrolyte composition, comprising:
(a) a homogeneous solvent system, said solvent system comprising a perfluropolyether (PFPE) and polyethylene oxide (PEO); and
(b) an alkali metal salt dissolved in said solvent system, wherein said PFPE and said PEO are included in said solvent system in a weight ratio (PFPE:PEO) of from 40:60 to 95:5.
2. The composition of claim 1 , wherein said alkali metal salt is a lithium salt.
3. The composition of claim 1 , wherein said alkali metal salt is a sodium salt.
4. The composition of claim 1 , wherein
said solvent system is included in said composition in an amount of from 70 to 95 percent by weight; and
said salt is included in said composition in an amount of from 5 to 30 percent by weight.
5. The composition of claim 1 , wherein:
said PEO has a weight average molecular weight of from 0.2 to 4 Kg/mol, and
said PFPE has a weight average molecular weight of from 0.4 to 20 Kg/mol.
6. The composition of claim 1 , wherein said PEO and said PFPE are crosslinkable.
7. The composition of claim 1 , further comprising an initiator and/or an electrode stabilizing agent.
8. The composition of claim 1 , wherein said composition is substantially free of carbonate solvent.
9. The composition of claim 1 , wherein said composition has a T g between −120° C. and −20° C.
10. The composition of claim 1 , wherein said composition does not ignite when heated to a temperature of 235° C. and then contacted to a flame for 15 seconds in a Kohler open cup rapid flash test apparatus.
11. The composition of claim 1 , wherein said composition has an electrochemical stability window of from 3 to 6 volts against Li/Li + .
12. A solid electrolyte composition for a battery, comprising:
(a) a solid polymer, said polymer comprising a crosslinked product of a crosslinkable perfluropolyether (PFPE) and a crosslinkable polyethylene oxide (PEO); and
(b) an alkali metal salt dissolved in said polymer, wherein said PFPE and said PEO are included in said solid polymer in a weight ratio (PFPE:PEO) of from 40:60 to 95:5.
13. The composition of claim 12 , wherein said alkali metal salt is a lithium salt.
14. The composition of claim 12 , wherein said alkali metal salt is a sodium salt.
15. The composition of claim 12 , wherein said composition is in the form of a film.
16. The composition of claim 12 , wherein said polymer is amorphous.
17. The composition of claim 12 , wherein
said solid polymer is included in said composition in an amount of from 70 to 95 percent by weight; and
said salt is included in said composition in an amount of from 5 to 30 percent by weight.
18. The composition of claim 12 , wherein:
said PEO has a weight average molecular weight of from 0.2 to 4 Kg/mol, and
said PFPE has a weight average molecular weight of from 0.4 to 20 Kg/mol.
19. The composition of claim 12 , further comprising an initiator and/or an electrode stabilizing agent.
20. The composition of claim 12 , wherein said composition is substantially free of carbonate solvent.
21. The composition of claim 12 , wherein said composition has a T g between −120° C. and −20° C.
22. The composition of claim 12 , wherein said composition does not ignite when heated to a temperature of 235° C. and then contacted to a flame for 15 seconds in a Kohler open cup rapid flash test apparatus.
23. The composition of claim 12 , wherein said composition has an electrochemical stability window of from 3 to 6 volts against Li/Li + .
24. A battery, comprising:
(a) an anode;
(b) a cathode; and
(c) a solid electrolyte composition operatively associated with said anode and cathode, wherein said solid electrolyte composition is the composition of claim 12 .
25. A battery, comprising:
(a) an anode;
(b) a cathode; and
(c) a liquid electrolyte composition operatively associated with said anode and cathode, wherein said liquid electrolyte composition comprises (a) a homogeneous solvent system comprising a perfluropolyether (PFPE) and polyethylene oxide (PEO) and (b) an alkali metal salt dissolved in said solvent system.
26. A method of making an electrolyte composition for a battery, comprising:
(a) combining perfluropolyether (PFPE), polyethylene oxide (PEO), alkali metal salt, and optionally a photoinitiator, in the absence of additional solvent under conditions in which a single phase solution solvent system is formed; and then optionally
(b) crosslinking said PFPE and said PEO to form a solid polymer having said alkali metal salt dissolved therein.
27. The method of claim 26 , wherein
said solvent system is included in said composition in an amount of from 70 to 95 percent by weight;
said salt is included in an amount of from 5 to 30 percent by weight; and
said PFPE and said PEO are included in said solvent system in a weight ratio (PFPE:PEO) of from 40:60 to 95:5.
28. The method of claim 26 , wherein said alkali metal salt is a lithium salt or sodium salt.