Method for stabilizing LiPF;, electrolyte solution for nonaqueous secondary batteries having excellent thermal stability, and nonaqueous secondary battery having excellent thermal stability

• US 9,472,829 B2
• Filed: 06/13/2013
• Issued: 10/18/2016
• Est. Priority Date: 06/15/2012
• Status: Active Grant

• Current Assignee: Tosoh F-Tech, Inc. (Tosoh Corporation)
• Original Assignee: Tosoh F-Tech, Inc. (Tosoh Corporation)
• Inventors: Aoki, Masahiro, Mimura, Hideyuki, Eguchi, Hisao
• Primary Examiner(s): Ruddock, Ula C
• Assistant Examiner(s): PARSONS, THOMAS H
• Application Number:
  US14/406,884
• Publication Number:
  US 20150140445A1
• Time in Patent Office: 1,223 Days
• US Class Current: 1/1
• CPC Class Codes: C07F 9/091 with hydroxyalkyl compounds with further substituents on alkyl
• CPC Class Codes: C07F 9/11 with hydroxyalkyl compounds without further substituents on alkyl
• CPC Class Codes: C07F 9/1411 with hydroxyalkyl compounds with further substituents on alkyl
• CPC Class Codes: C07F 9/224 Phosphorus triamides
• CPC Class Codes: C07F 9/24 Esteramides
• CPC Class Codes: C07F 9/2458 of aliphatic amines
• CPC Class Codes: C07F 9/2462 of unsaturated acyclic amines
• CPC Class Codes: C07F 9/2466 of cycloaliphatic amines
• CPC Class Codes: C07F 9/247 of aromatic amines (N-C aromatic linkage)
• CPC Class Codes: C07F 9/650952 having the nitrogen atoms in the positions 1 and 4
• CPC Class Codes: C07F 9/6533 Six-membered rings
• CPC Class Codes: C07F 9/6544 Six-membered rings
• CPC Class Codes: H01G 11/56 Solid electrolytes, e.g. gels; Additives therein
• CPC Class Codes: H01G 11/58 Liquid electrolytes
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0567 characterised by the additives
• CPC Class Codes: H01M 10/0568 characterised by the solutes
• CPC Class Codes: H01M 10/0569 characterised by the solvents
• CPC Class Codes: H01M 2300/0025 Organic electrolyte
• CPC Class Codes: H01M 2300/0037 Mixture of solvents
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• CPC Class Codes: Y02E 60/13 : Energy storage using capacitors
• CPC Class Codes: Y02P 70/50 : Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries

Abstract

A method for stabilizing a solution that contains LiPF₆ by increasing thermal stability of LiPF₆ without changing the structure thereof; an electrolyte solution for nonaqueous secondary batteries, which has increased thermal stability; and a nonaqueous secondary battery which has increased thermal stability. The solution containing LiPF₆ contains a phosphoric acid ester amide in such an amount that the molar ratio of the phosphoric acid ester amide relative to LiPF₆ is 0.001-2.

Claims

1. A method for stabilizing LiPF₆, comprising mixing a phosphoric acid ester amide represented by the following general formula (I) with LiPF₆ in a solution comprising LiPF₆, in such an amount that a molar ratio of the phosphoric acid ester amide with respect to LiPF₆ is 0.001 to 2:

2. The method for stabilizing LiPF₆ according to claim 1, further comprising preparing the phosphoric acid ester amide.

3. The method for stabilizing LiPF₆ according to claim 1, wherein m is 1.

4. The method for stabilizing LiPF₆ according to claim 1, wherein R³ is a fluorine-containing alkyl group.

5. The method for stabilizing LiPF₆ according to claim 1, wherein each of R¹ and R² independently represents a methyl group, an ethyl group, a n-propyl group or an isopropyl group, and R³ represents a 2,2-difluoroethyl group, a 2,2,2-trifluoroethyl group, a 2,2,3,3-tetrafluoropropyl group or a 2,2,3,3,3-pentafluoropropyl group.

6. The method for stabilizing LiPF₆ according to claim 1, wherein the molar ratio of the phosphoric acid ester amide with respect to LiPF₆ is 0.001 to 1.

7. The method for stabilizing LiPF₆ according to claim 1, wherein the molar ratio of the phosphoric acid ester amide with respect to LiPF₆ is 0.001 to 0.76.

8. The method for stabilizing LiPF₆ according to claim 1, wherein the solution comprising LiPF₆ comprises a cyclic carbonate and/or a chain carbonate as a solvent.

9. A nonaqueous electrolyte solution comprising LiPF₆ as an electrolyte and a cyclic carbonate and/or a chain carbonate as a solvent, and a phosphoric acid ester amide represented by the following general formula (I) in such an amount that a molar ratio of the phosphoric acid ester amide with respect to LiPF₆ is 0.001 to 2:

10. The nonaqueous electrolyte solution according to claim 9, wherein the nonaqueous electrolyte solution has increased thermal and storage stabilities under a condition at a high temperature of 30 to 100°

C.

11. A nonaqueous secondary battery comprising a positive electrode and a negative electrode that are capable of occluding and releasing lithium, a separator, an electrolyte solution comprising LiPF₆ as an electrolyte and a cyclic carbonate and/or a chain carbonate as a solvent and a phosphoric acid ester amide represented by the following general formula (I) in such an amount that a molar ratio of the phosphoric acid ester amide with respect to LiPF₆ is 0.001 to 2: