Sandwich cathode design for alkali metal electrochemical cell with high discharge rate capability

• US 6,551,747 B1
• Filed: 04/27/2000
• Issued: 04/22/2003
• Est. Priority Date: 04/27/2000
• Status: Expired due to Term

• Current Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Original Assignee: Wilson Greatbatch Technologies, Inc.
• Inventors: Gan, Hong
• Primary Examiner(s): CHANEY, CAROL DIANE
• Application Number:
  US09/560,060
• Time in Patent Office: 1,090 Days
• Field of Search: 429/128, 429/231.7, 429/219, 429/209, 429/244, 429/231.2, 429/245, 429/233
• US Class Current: 429/245
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0568 characterised by the solutes
• CPC Class Codes: H01M 10/0569 characterised by the solvents
• CPC Class Codes: H01M 2004/028 Positive electrodes
• CPC Class Codes: H01M 2300/0037 Mixture of solvents
• CPC Class Codes: H01M 4/02 Electrodes composed of, or comprising, active material
• CPC Class Codes: H01M 4/06 Electrodes for primary cells
• CPC Class Codes: H01M 4/366 as layered products
• CPC Class Codes: H01M 4/5825 Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• CPC Class Codes: H01M 4/583 Carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/5835 Comprising fluorine or fluoride salts
• CPC Class Codes: H01M 4/661 Metal or alloys, e.g. alloy coatings H01M4/669 take precedence
• CPC Class Codes: H01M 4/70 characterised by shape or form
• CPC Class Codes: H01M 50/534 characterised by the material of the leads or tabs
• CPC Class Codes: H01M 6/16 with organic electrolyte H01M6/18 takes precedence
• CPC Class Codes: H01M 6/166 by the solute

Abstract

A new sandwich cathode design having a second cathode active material of a relatively high energy density but of a relatively low rate capability sandwiched between two current collectors and with a first cathode active material having a relatively low energy density but of a relatively high rate capability in contact with the opposite sides of the two current collectors, is described. The present cathode design is useful for powering an implantable medical device requiring a high rate discharge application.

Claims

1. An electrochemical cell, which comprises:

a) an anode;

b) a cathode of a first cathode active material different than a second cathode active material, the first cathode active material being of a first energy density and a first rate capability and the second cathode active material being of a second energy density and a second rate capability, and wherein the cathode further comprises first and second current collectors with the second cathode active material sandwiched between the current collectors and with the first cathode active material contacting the first and second current collectors opposite the second cathode active material, and wherein the first energy density of the first cathode active material is less than the second energy density of the second cathode active material while the first rate capability of the first cathode active material is greater than the second rate capability of the second cathode active material; and

c) an electrolyte activating the anode and the cathode.

2. The electrochemical cell of claim 1 wherein the first cathode active material is selected from the group consisting of CF_x, Ag₂O, Ag₂O₂, CuF, Ag₂CrO₄, MnO₂, SVO, and mixtures thereof.

3. The electrochemical cell of claim 1 wherein the second cathode active material is selected from the group consisting of SVO, CSVO, V₂O_5, MnO₂, LiCoO₂, LiNiO₂, LiMnO₂, CuO₂, TiS, Cu₂S, FeS, FeS₂, copper oxide, copper vanadium oxide, and mixtures thereof.

4. The electrochemical cell of claim 1 wherein the cathode has the configuration:

SVO/first current collector/CF_x/second current collector/SVO.

5. The electrochemical cell of claim 1 wherein the cathode has the configuration:

SVO/first current collector/SVO/CF_x/SVO/second current collector/SVO.

6. The electrochemical cell of claim 1 wherein the anode is of an alkali metal.

7. The electrochemical cell of claim 1 wherein the electrolyte is a nonaqueous electrolyte.

8. An electrochemical cell, which comprises:

a) an anode;

b) a cathode of SVO as a first cathode active material and CF_x as a second cathode active material, wherein the second cathode active material is sandwiched between a first and second current collectors with the first cathode active material contacting the first and second current collectors opposite the second cathode active material; and

c) an electrolyte activating the anode and the cathode.

9. The electrochemical cell of claim 8 wherein the first and second current collectors are selected from the group consisting of stainless steel, titanium, tantalum, platinum, gold, aluminum, cobalt nickel alloys, nickel-containing alloys, highly alloyed ferritic stainless steel containing molybdenum and chromium, and nickel-, chromium-, and molybdenum-containing alloys.

10. The electrochemical cell of claim 8 wherein the first and second current collectors are titanium having a coating selected from the group consisting of graphite/carbon material, iridium, iridium oxide and platinum provided thereon.

11. The electrochemical cell of claim 8 wherein the anode is lithium and the first and second current collectors are titanium.

12. The electrochemical cell of claim 8 wherein the cathode has the configuration:

SVO/first titanium current collector/CF_x/second titanium current collector/SVO.

13. The electrochemical cell of claim 8 wherein the cathode has the configuration:

SVO/first titanium current collector/SVO/CF_x/SVO/second titanium current collector/SVO.

14. The electrochemical cell of claim 8 wherein the electrolyte has a first solvent selected from an ester, a linear ether, a cyclic ether, a dialkyl carbonate, and mixtures thereof, and a second solvent selected from a cyclic carbonate, a cyclic ester, a cyclic amide, and mixtures thereof.

15. The electrochemical cell of claim 14 wherein the first solvent is selected from the group consisting of tetrahydrofuran (THF), methyl acetate (MA), diglyme, trigylme, tetragylme, dimethyl carbonate (DMC), 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1-ethoxy,2-methoxyethane (EME), ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, diethyl carbonate, dipropyl carbonate, and mixtures thereof, and the second solvent is selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate, acetonitrile, dimethyl sulfoxide, dimethyl, formamide, dimethyl acetamide, γ

-valerolactone, γ

-butyrolactone (GBL), N-methyl-pyrrolidinone (NMP), and mixtures thereof.

16. The electrochemical cell of claim 8 including a lithium salt selected from the group consisting of LiPF₆, LiBF₄, LiAsF₆, LiSbF₆, LiClO₄, LiO₂, LiAlCl₄, LiGaCl₄, LiC(SO₂CF₃)₃, LiN(SO₂CF₃)₂, LiSCN, LiO₃SCF₃, LiC6F₅SO₃, LiO₂CCF₃, LiSO₆F, LiB(C₆H₅)₄ and LiCF₃SO₃, and mixtures thereof.

17. The electrochemical cell of claim 8 wherein the electrolyte is 0.8M to 1.5M LiAsF₆ or LiPF₆ dissolved in a 50:

50 mixture, by volume, of propylene carbonate as the first solvent and 1,2-dimethoxyethane as the second solvent.

18. The electrochemical cell of claim 8 wherein the anode is of an alkali metal.

19. The electrochemical cell of claim 8 wherein the electrolyte is a nonaqueous electrolyte.

20. An electrochemical cell, which comprises:

a) an anode of an alkali metal;

b) a cathode of a first cathode active material selected from the group consisting of SVO, CSVO, V₂O₅, MnO₂, LiCoO₂, LiNiO₂, LiMnO₂, CuO₂, TiS₂, Cu₂S, FeS, FeS₂, copper oxide, copper vanadium oxide, and mixtures thereof, different than a second cathode active material, the first cathode active material being of a first energy density and a first rate capability and the second cathode active material being of a second energy density and a second rate capability, and wherein the cathode further comprises first and second current collectors with the second cathode active material sandwiched between the current collectors and with the first cathode active material contacting the first and second current collectors opposite the second cathode active material, and wherein the first energy density of the first cathode active material is less than the second energy density of the second cathode active material while the first rate capability of the first cathode active material is greater than the second rate capability of the second cathode active material; and

c) a nonaqueous electrolyte activating the anode and the cathode.

21. The electrochemical cell of claim 20 wherein the first cathode active material is selected from the group consisting of CF_x, Ag₂O, Ag₂O₂, CuF, Ag₂CrO₄, MnO₂, SVO, and mixtures thereof.

22. The electrochemical cell of claim 20 wherein the current collector is selected from the group consisting of stainless steel, titanium, tantalum, platinum, gold, aluminum, cobalt nickel alloys, nickel-containing alloys, highly alloyed ferritic stainless steel containing molybdenum and chromium, and nickel-, chromium-, and molybdenum-containing alloys.

23. An electrochemical-cell, which comprises:

a) a lithium anode;

b) a cathode of a first cathode active material selected from the group consisting of CF_x, Ag₂O, Ag₂O₂, CuF, Ag₂CrO₄, MnO₂, SVO, and mixtures thereof, sandwiched between a first and second titanium current collectors with a second cathode active material selected from the group consisting of SVO, CSVO, V₂O₅, MnO₂, LiCoO₂, LiNiO₂, LiMnO₂, CuO₂, TiS, Cu₂S, FeS, FeS₂, copper oxide, copper vanadium oxide, and mixtures thereof, contacting the first and second current collectors opposite the first cathode active material; and

c) a nonaqueous electrolyte activating the anode and the cathode.

24. A method for powering an implantable medical device, comprising the steps of:

a) providing the medical device;

b) providing an electrochemical cell, comprising the steps of;

i) providing an anode;

ii) providing a cathode of a first cathode active material different than a second cathode active, material, the first cathode active material of a first energy density and a first rate capability and the second cathode active material of a second energy density and a second rate capability, and wherein the cathode further comprises first and second current collectors with the second cathode active material sandwiched between the current collectors and with the first cathode active material contacting the first and second current collectors opposite the second cathode active material, and wherein the first energy density of the first cathode active material is less than the second energy density of the second cathode active material while the first rate capability of the first cathode active material is greater than the second rate capability of the second cathode active material, and

iii) activating the anode and cathode with an electrolyte; and

c) electrically connecting the electrochemical cell to the medical device.

25. The method of claim 24 including selecting the first cathode active material from the group consisting of CF_x, Ag₂O, Ag₂O₂, CuF, Ag₂CrO₄, MnO₂, SVO, and mixtures thereof.

26. The method of claim 24 including selecting the second cathode active material from the group consisting of SVO, CSVO, V₂O₅, MnO₂, LiCoO₂, LiNiO₂, LiMnO₂, CuO₂, TiS, Cu₂S, FeS, FeS₂, copper oxide, copper vanadium oxide, and mixtures thereof.

27. The method of claim 24 wherein the anode is lithium, the first cathode active material is CF_x, the second cathode active material is SVO.

28. The method of claim 24 including providing the cathode having the configuration:

SVO/first current collector/CF_x/second current collector/SVO.

29. The method of claim 24 including providing the cathode having the configuration:

SVO/first current collector/SVO/CF_x/SVO/second current collector/SVO.

30. The method of claim 24 including providing the anode of an alkali metal.

31. The method of claim 24 including providing the electrolyte a nonaqueous electrolyte.

32. An electrochemical cell, which comprises:

a) an anode;

b) a cathode of a first cathode active material different than a second cathode active material, the first cathode active material of a first energy density and a first rate capability and the second cathode active material of a second energy density and a second rate capability, wherein the second cathode active material has spaced apart first and second major sides with at least one current collector contacting each of the first and second major sides and wherein the first cathode active material is contacted to the at least one current collector opposite the second cathode active material and faces the anode; and

c) an electrolyte activating the anode and the cathode.

33. The electrochemical cell of claim 32 wherein the anode is lithium and the cathode has the configuration:

SVO/current collector/CF_x/current collector/SVO.