Rechargeable lithium intercalation battery with hybrid polymeric electrolyte

• US 5,296,318 A
• Filed: 03/05/1993
• Issued: 03/22/1994
• Est. Priority Date: 03/05/1993
• Status: Expired due to Fees

• Current Assignee: Valence Technology Incorporated (Lithium Werks B.V.)
• Original Assignee: Bell Communications Research, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Gozdz, Antoni S., Tarascon, Jean-Marie, Schmutz, Caroline N.
• Primary Examiner(s): Maples, John S.
• Application Number:
  US08/026,904
• Time in Patent Office: 382 Days
• Field of Search: 429/192, 429/194, 429/191, 429/197
• US Class Current: 429/316
• CPC Class Codes: C08J 2327/16 Homopolymers or copolymers of vinylidene fluoride
• CPC Class Codes: C08J 9/28 by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0565 Polymeric materials, e.g. gel-type or solid-type
• CPC Class Codes: H01M 50/426 Fluorocarbon polymers
• CPC Class Codes: H01M 50/494 Tensile strength
• CPC Class Codes: H01M 50/497 Ionic conductivity
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A rechargeable battery comprises lithium intercalation compound electrodes and an interposed electrolyte of flexible polymer containing a lithium salt dissolved in a polymer-compatible solvent. Preferred components include tertiary lithium manganese oxide compound positive electrodes, carbon negative electrodes, and poly(vinylidene fluoride) copolymer electrolyte layers containing about 20 to 70% of a solution of lithium salt in a medium boiling solvent comprising such solvents as ethylene carbonate, propylene carbonate, and dimethyl carbonate. The electrolyte layers may be employed in the form of individual separator films or as a coated component of multilayer battery structures to provide electrical ionic conductivity up to about 10^-3 S/cm.

Claims

1. A solid electrolyte for a rechargeable lithium intercalation battery cell comprising a dissociable lithium salt dispersed in a polymeric matrix

characterized in that said electrolyte comprises a substantially self-supporting film of a copolymer of vinylidene fluoride with 8 to 25% by weight hexafluoropropylene, said film having homogeneously distributed therein 20 to 70% by weight of a solution of at least one lithium salt in a medium-boiling solvent.

2. An electrolyte according to claim 1

characterized in that said lithium salt is selected from the group consisting of LiPF₆, LiAsF₆, LiClO₄, LiN(CF₃ SO₂)₂, LiBF₄, LiCF₃ SO₃, and LiSbF₆.

3. An electrolyte according to claim 1

characterized in that said solvent is selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethoxyethane, diethyl carbonate, dimethoxyethane, dipropyl carbonate, and mixtures thereof.

4. An electrolyte according to claim 1

characterized in that

a) said lithium salt is selected from the group consisting of LiPF₆, LiAsF₆, LiClO₄, LiN(CF₃ SO₂)₂, LiBF₄, LiCF₃ SO₃, and LiSbF₆ ;

and

b) said solvent is selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethoxyethane, diethyl carbonate, dimethoxyethane, dipropyl carbonate, and mixtures thereof.

5. An electrolyte according to claim 1

characterized in that said copolymer contains 12 to 20% by weight hexafluoropropylene.

6. An electrolyte according to claim 4

characterized in that said copolymer contains 12 to 15% by weight hexafluoropropylene.

7. An electrolyte according to claim 6

characterized in that said film comprises 40 to 60% by weight of said lithium salt solution.

8. A rechargeable lithium intercalation battery cell comprising a positive electrode, a negative electrode, and an ionically conductive solid electrolyte disposed between said electrodes

characterized in that said electrolyte comprises a substantially self-supporting film of a copolymer of vinylidene fluoride with 8 to 25% by weight hexafluoropropylene, said film having homogeneously distributed therein 20 to 70% by weight of a solution of at least one lithium salt in a medium-boiling solvent.

9. A battery cell according to claim 8

characterized in that said negative electrode comprises a material selected from the group consisting of lithium, lithium alloys, and carbon.

10. A battery cell according to claim 9

characterized in that said positive electrode comprises a lithium intercalation compound.

11. A battery cell according to claim 8

characterized in that said electrolyte film comprises an individual separator element interposed between said electrodes.

12. A battery cell according to claim 8

characterized in that said electrolyte film comprises a layer coated on at least one of said electrodes.

13. A battery cell according to claim 8

characterized in that said lithium salt is selected from the group consisting of LiPF₆, LiAsF₆, LiClO₄, LiN(CF₃ SO₂)₂, LiBF₄, LiCF₃ SO₃, and LiSbF₆.

14. An electrolyte according to claim 8

characterized in that said solvent is selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethoxyethane, diethyl carbonate, dimethoxyethane, dipropyl carbonate, and mixtures thereof.

15. An electrolyte according to claim 8

characterized in that said lithium salt is selected from the group consisting of LiPF₆, LiAsF₆, LiClO₄, LiN(CF₃ SO₂)₂, LiBF₄, LiCF₃ SO₃, and LiSbF₆ ;

and

said solvent is selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethoxyethane, diethyl carbonate, dimethoxyethane, dipropyl carbonate, and mixtures thereof.

16. An electrolyte according to claim 15

characterized in that said copolymer contains 12 to 20% by weight hexafluoropropylene.

17. An electrolyte according to claim 16

characterized in that said copolymer contains 12 to 15% by weight hexafluoropropylene.

18. An electrolyte according to claim 17

characterized in that said film comprises 40 to 60% by weight of said lithium salt solution.