Borate salts, polymers and composites
Described herein are borate salts useful as additives, binders, and electrolyte salts for solid state lithium ion batteries. In particular, the borate salts of Formula (I), Formula (II) and Formula (III) as described herein: can be bound to an existing polymer to provide polymeric binders for ceramic solid state electrolytes that are themselves capable of ion transport independent of the ceramic.
1. A process for preparing potassium bis(2-allyl-2-fluoromalonato)borate comprising the steps of:
(a) reacting diethyl 2-fluoromalonate with about one allyl bromide in the presence of a base to form diethyl 2-allyl-2-fluoromalonate;
(b) reacting the diethyl 2-allyl-2-fluoromalonate with an aqueous base to form a 2-allyl-2-fluoromalonate salt;
(c) acidifying the 2-allyl-2-fluoromalonate salt with a strong acid to form 2-allyl-2-fluoromalonic acid; and
(d) combining the 2-allyl-2-fluoromalonic acid with about 0.25 equivalents of potassium carbonate and about 0.5 equivalents of boric acid in an aprotic solvent capable of forming an azeotrope with water; and refluxing the resulting mixture while azeotropically removing water formed from reaction of the 2-allyl-2-fluoromalonic acid with the potassium carbonate and the boric acid to thereby form potassium bis(2-allyl-2-fluoromalonato)borate.
2. The method of claim 1 , wherein the base in step (a) comprises sodium ethoxide.
3. The method of claim 1 , wherein the base in step (a) comprises sodium methoxide.
4. The method of claim 1 , wherein step (a) is performed in ethanol.
5. The method of claim 1 , wherein the aqueous base in step (b) comprises sodium hydroxide dissolved in an aqueous solvent.
6. The method of claim 5 , wherein the aqueous solvent comprises a mixture of water and ethanol.
7. The method of claim 5 , wherein the aqueous solvent comprises a mixture of water and methanol.
8. The method of claim 1 , wherein the aqueous base in step (b) comprises potassium hydroxide dissolved in an aqueous solvent.
9. The method of claim 8 , wherein the aqueous solvent comprises a mixture of water and ethanol.
10. The method of claim 8 , wherein the aqueous solvent comprises a mixture of water and methanol.
11. The method of claim 1 , wherein the strong acid in step (c) comprises a mineral acid.
12. The method of claim 11 wherein the mineral acid comprises hydrochloric acid.
13. The method of claim 1 , wherein the aprotic solvent in step (d) comprises diethylcarbonate.
14. A process for preparing potassium bis(2-allyl-2-fluoromalonato)borate comprising the steps of:
(a) reacting a solution of diethyl 2-fluoromalonate in ethanol with allyl bromide in the presence of sodium ethoxide to form diethyl 2-allyl-2-fluoromalonate;
(b) reacting the diethyl 2-allyl-2-fluoromalonate with aqueous sodium hydroxide to form a disodium 2-allyl-2-fluoromalonate;
(c) acidifying the disodium 2-allyl-2-fluoromalonate with a hydrochloric acid to form 2-allyl-2-fluoromalonic acid; and
(d) combining the 2-allyl-2-fluoromalonic acid with about 0.25 equivalents of potassium carbonate and about 0.5 equivalents of boric acid in diethylcarbonate; and refluxing the resulting mixture while azeotropically removing water formed from reaction of the 2-allyl-2-fluoromalonic acid with the potassium carbonate and the boric acid to thereby form potassium bis(2-allyl-2-fluoromalonato)borate.
15. A process for preparing a bis(2-allyl-2-fluoromalonato)borate metal salt comprising the steps of:
reacting 2-allyl-2-fluoromalonic acid with about 0.25 equivalents of a metal carbonate salt and about 0.5 equivalents of boric acid in an aprotic solvent capable of forming an azeotrope with water; and
refluxing the resulting mixture while azeotropically removing water formed from reaction of the 2-allyl-2-fluoromalonic acid with the metal carbonate and the boric acid to thereby form the bis(2-allyl-2-fluoromalonato)borate metal salt.
16. The process of claim 15 , wherein the metal of the metal carbonate salt is potassium.
17. The process of claim 15 , wherein the metal of the metal carbonate salt is lithium.