Electrolyte for LI/SVO batteries

• US 5,766,797 A
• Filed: 11/27/1996
• Issued: 06/16/1998
• Est. Priority Date: 11/27/1996
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Chen, Kevin, Crespi, Ann M.
• Primary Examiner(s): Skapars, Anthony
• Application Number:
  US08/757,220
• Time in Patent Office: 566 Days
• Field of Search: 429/194, 429/196, 429/197, 429/218, 429/219
• US Class Current: 429/332
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0564 the electrolyte being constituted of organic materials only
• CPC Class Codes: H01M 10/0568 characterised by the solutes
• CPC Class Codes: H01M 10/0569 characterised by the solvents
• CPC Class Codes: H01M 2300/004 Three solvents
• CPC Class Codes: H01M 4/364 as mixtures
• CPC Class Codes: H01M 4/483 for non-aqueous cells H01M4/485 takes precedence
• CPC Class Codes: H01M 4/54 of silver
• CPC Class Codes: H01M 4/5825 Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• CPC Class Codes: H01M 4/5835 Comprising fluorine or fluoride salts
• CPC Class Codes: H01M 50/103 prismatic or rectangular H01M50/109, H01M50/11 take precedence
• CPC Class Codes: H01M 6/10 with wound or folded electrodes
• CPC Class Codes: H01M 6/164 by the solvent
• CPC Class Codes: H01M 6/166 by the solute
• CPC Class Codes: H01M 6/5044 Cells or batteries structurally combined with cell condition indicating means
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A lithium/silver vanadium oxide cell is disclosed that includes an improved electrolyte composition having the solvents propylene carbonate and 1,2-dimethoxyethane, and an additional third solvent that reduces the solubility of the composition of the silver vanadium cathode material. Preferably, the third solvent is a dialkyl carbonate such as dimethyl carbonate, diethyl carbonate or ethylmethyl carbonate. The improved electrolyte composition reduces the build up of resistance in the cell during cell discharge, and can affect the cell'"'"'s performance in implantable cardiac defibrillator applications.

Claims

1. An electrochemical cell, comprising:

(a) an anode comprising lithium;

(b) a cathode comprising a silver vanadium oxide material;

(c) an electrolyte comprising a solute and a solvent mixture of propylene carbonate and 1,2-dimethoxyethane, the solvent mixture further comprising a third solvent that is a dialkyl carbonate selected from the group consisting of dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate, the third solvent being homogeneously miscible with the solvent mixture of propylene carbonate and 1,2-dimethoxyethane, the third solvent reducing the solubility of the silver vanadium oxide material.

2. An electrochemical cell as in claim 1 wherein the solvent mixture comprises about 20-30 percent by volume of propylene carbonate, 20-30 percent by volume of dimethyl carbonate and 40-60 percent by volume of 1,2-dimethoxyethane.

3. An electrochemical cell as in claim 1, wherein the solute is selected from the group consisting of lithium hexafluoroarsenate (LiAsF6), lithium hexafluorophosphate (LiPF₆), lithium imide (Li(CF₃ SO₂)₂ N), lithium tris(trifluoromethane sulfonate) carbide ((Li(CF₃ SO₂)₃ C), lithium tetrafluoroborate (LiBF₄), lithium triflate (LiCF₃ SO₃), and lithium perchlorate (LiClO₄).

4. In an electrochemical cell having a first quantity of lithium anode material and a second quantity of silver vanadium oxide cathode material, the cell producing a voltage discharge curve having a second voltage plateau at about 2.6 volts and having an electrolyte composition in contact with at least a portion of the first quantity of lithium anode material and in contact with at least a portion of the second quantity of silver vanadium oxide cathode material, the electrolyte composition including a solute and a solvent mixture of propylene carbonate and 1,2-dimethoxyethane, the solvent mixture having a dialkyl carbonate as a third solvent.

5. An electrochemical cell as in claim 4, wherein the dialkyl carbonate is selected from the group consisting of dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate.

6. An electrochemical cell as in claim 5, wherein the solvent mixture comprises about 20-30 percent by volume of propylene carbonate, 20-30 percent by volume of dimethyl carbonate and 40-60 percent by volume of 1,2-dimethoxyethane.

7. An electrochemical cell as in claim 4, wherein the solute is selected from the group consisting of lithium hexafluoroarsenate (LiAsF6), lithium hexafluorophosphate (LiPF₆), lithium imide (Li(CF₃ SO₂)₂ N), lithium tris(trifluoromethane sulfonate) carbide ((Li(CF₃ SO₂)₃ C), lithium tetrafluoroborate (LiBF₄), lithium triflate (LiCF₃ SO₃), and lithium perchlorate (LiClO₄).

8. An electrochemical cell as in claim 5, wherein the solute is selected from the group consisting of lithium hexafluoroarsenate (LiAsF6), lithium hexafluorophosphate (LiPF₆), lithium imide (Li(CF₃ SO₂)₂ N), lithium tris(trifluoromethane sulfonate) carbide ((Li(CF₃ SO₂)₃ C), lithium tetrafluoroborate (LiBF₄), lithium triflate (LiCF₃ SO₃), and lithium perchlorate (LiClO₄).

9. An electrochemical cell as in claim 4, wherein the solute is selected from the group consisting of lithium hexafluoroarsenate (LiAsF6), lithium hexafluorophosphate (LiPF₆), lithium imide (Li(CF₃ SO₂)₂ N), lithium tris(trifluoromethane sulfonate) carbide ((Li(CF₃ SO₂)₃ C), lithium tetrafluoroborate (LiBF₄), lithium triflate (LiCF₃ SO₃), and lithium perchlorate (LiClO₄).