Ionic liquids for solvating cyclic carbonates
Ionic liquids that can be used to solvate cyclic carbonate esters and halogenated analogues thereof are disclosed.
1. A method of lowering the crystallization and melting points of cyclic carbonate by combining the cyclic carbonate with 1-(3-acetylbutyl)-1-methylpyrrolidinium TFSI in a range of from about 1:3 wt. % to about 4:1 wt. % of a ratio of cyclic carbonate to 1-(3-acetylbutyl)-1-methylpyrrolidinium TFSI.
2. The method of claim 1 wherein the cyclic carbonate is selected from the group consisting of ethylene carbonate, fluoroethylene carbonate, lactones, a cyclic carbonate comprising substituted halogen or haloalkane groups, and any mixture thereof.
3. A method of forming an electrolyte for secondary batteries with a liquidus range extending to at least −50° C. comprising adding an alkali metal salt and an organic co-solvent further comprising the method of claim 1 .
4. The method of claim 3 , wherein the alkali metal salt has a cation of lithium.
5. The method of claim 3 , wherein the total molar concentration of the alkali metal salt in the electrolyte formulation is between about 0.1 molar to about 2 molar.
6. The method of claim 3 wherein the cyclic carbonate is selected from the group consisting of ethylene carbonate, fluoroethylene carbonate, lactones, a cyclic carbonate comprising substituted halogen or haloalkane groups, and any mixture thereof.
7. The method of claim 3 wherein the organic co-solvent is one or more species selected from the group consisting of open-chain carbonates, cyclic carbonates, carboxylic acid esters, nitriles, ethers, sulfones, ketones, lactones, dioxolanes, glymes, crown ethers, and mixtures thereof.
8. A method of forming an electrochemical cell comprising adding a positive electrode and a negative electrode further comprising the method of claim 3 .
9. The method of claim 8 wherein the positive electrode comprises a lithium metal oxide or phosphate with an electrochemical window of 3 to 6 volts relative to lithium.
10. The method of claim 8 wherein the negative electrode comprises at least one of graphite, silicon, lithium titanate, or lithium metal.
11. The method of claim 8 wherein the alkali metal salt has a cation of lithium.
12. The method of claim 8 wherein the total molar concentration of the alkali metal salt in the electrolyte formulation is between about 0.1 molar to about 2 molar.
13. The method of claim 8 wherein the cyclic carbonate is one of ethylene carbonate, fluoroethylene carbonate, lactones, a cyclic carbonate comprising substituted halogen or haloalkane groups, or any mixture thereof.
14. The method of claim 8 wherein the organic co-solvent is one or more species selected from the group consisting of open-chain carbonates, cyclic carbonates, carboxylic acid esters, nitriles, ethers, sulfones, ketones, lactones, dioxolanes, glymes, crown ethers, and mixtures thereof.