Ion conducting fluoropolymer carbonates for alkali metal ion batteries
Liquid or solid electrolyte compositions are described that comprise a homogeneous solvent system and an alkali metal salt dissolved in said solvent system. The solvent system may comprise a fluoropolymer, having one or two terminal carbonate groups covalently coupled thereto. Batteries containing such electrolyte compositions are also described.
1. A liquid or solid electrolyte composition, comprising:
(a) a homogeneous solvent system, said solvent system comprising a compound of Formula I:
wherein:
R f is a fluoropolymer having a weight average molecular weight of from 0.2 to 20 Kg/mol; and
R′ and R″ are each independently selected aliphatic, aromatic, or mixed aliphatic and aromatic groups; and
(b) an alkali metal salt dissolved in said solvent system.
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. A liquid or solid electrolyte composition, comprising:
(a) a homogeneous solvent system, said solvent system comprising a compound of Formula II:
wherein:
R f is a perfluoropolymer having a weight average molecular weight of from 0.2 to 20 Kg/mol; and
R′ is an aliphatic, aromatic, or mixed aliphatic and aromatic group; and
(b) an alkali metal salt dissolved in said solvent system.
6. The composition of claim 5 , wherein R f is a perfluoropolyether.
7. The composition of claim 1 , further comprising an electrode stabilizing agent.
8. The composition of claim 1 , wherein said composition is substantially free of volatile 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. The composition of claim 1 , wherein said fluoropolymer is amorphous.
13. A battery, comprising:
(a) an anode;
(b) a cathode; and
(c) a liquid or solid electrolyte composition operatively associated with said anode and cathode, wherein said electrolyte composition is the composition of claim 1 .
14. The battery of claim 13 , wherein at least one of said anode and said cathode comprises a carbon electrode.
15. A fluoropolymer compound selected from the group consisting of Formula I and Formula II,
wherein:
R f is a perfluoropolyether having a weight average molecular weight of from 0.2 to 20 Kg/mol; and
R′ and R″ are each independently selected from aliphatic, aromatic, or mixed aliphatic and aromatic groups.
16. The fluoropolymer compound of claim 15 , wherein the perfluoropolyether is amorphous.
17. The composition of claim 1 , wherein R f is a perfluoropolymer.
18. The composition of claim 17 , wherein R f is a perfluoropolyether.
19. The composition of claim 5 , 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.
20. The composition of claim 5 , wherein said perfluoropolymer is amorphous.