Electrolytes, cells and methods of forming passivation layers

• US 20060216612A1
• Filed: 12/15/2005
• Published: 09/28/2006
• Est. Priority Date: 01/11/2005
• Status: Abandoned Application

• Current Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Original Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Inventors: Ivanov, Sergei Vladimirovich, Casteel, William Jack Jr., Jambunathan, Krishnakumar, Dantsin, Gennady
• Application Number:
  US11/300,287
• Publication Number:
  US 20060216612A1
• Time in Patent Office: Days
• US Class Current: 429/326
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0566 Liquid materials
• CPC Class Codes: H01M 10/0567 characterised by the additives
• CPC Class Codes: H01M 10/0568 characterised by the solutes
• CPC Class Codes: H01M 4/131 Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• CPC Class Codes: H01M 4/133 Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

Electrolytes having a second cycle reduction current at 0.3 V vs Li/Li⁺ that is less than that of the first cycle. The electrolyte comprising a salt, which will not electrochemically passivate. A cell comprising a positive electrode, a negative electrode and an electrolyte having a second cycle reduction current at 0.3 V vs Li/Li⁺ that is less than that of the first cycle, said electrolyte comprising a salt, which will not electrochemically passivate. A method of forming an SEI layer in a cell comprising a positive electrode, a negative electrode and an electrolyte, said method comprising the step of overcharging the electrolyte prior to fabricating the cell, or said cell during the formation cycle.

Claims

1. An electrolyte having a second cycle reduction current at 0.3 V vs Li/Li⁺ that is less than the reduction current of the first cycle, said electrolyte comprising a salt which will not electrochemically passivate.

2. An electrolyte having a second cycle reduction current that is less than the reduction current of the first cycle, said electrolyte comprising a salt of the formula:

Li_aQ

where Q is a borate cluster anion or heteroborate cluster anion, and a is 1 or 2.

3. The electrolyte of claim 2 further comprising at least one additive.

4. The electrolyte of claim 3 wherein said additive comprises at least one inorganic compound.

5. The electrolyte of claim 3 wherein said additive comprises at least one member selected from the group consisting of boron, phosphorous, sulfur, fluorine, carbon and boron.

6. The electrolyte of claim 3 wherein said additive comprises at least one member selected from the group consisting of lithium hexafluorophosphate (LiPF₈), lithium bis-oxalatoborate (LiBOB), lithium perchlorate (LiClO₄), lithium hexafluoroarsenate (LiAsF₆), lithium trifluoromethanesulfonate (LiCF₃SO₃), lithium trifluoromethanesulfonimide (Li(CF₃SO₂)₂N, lithium tetrafluoroborate (LiBF₄), lithium tetrachloroaluminate (LiClO4), lithium hexafluoroantimonate (LiSbF₆), CO₂, phosphate esters, borate esters, and water.

7. The electrolyte of claim 3 wherein said additive comprises at least one chelato borate salt.

8. The electrolyte of claim 3 wherein said additive comprises at least one member selected from the group consisting of carbonates, chloroethylene carbonate, vinylene carbonate, vinylethylenecarbonate, sulfites, ethylene sulfite, propane sulfone, propylene sulfite, butyrolactones, phenylethylene carbonate, phenylvinylene carbonate, catechol carbonate, vinyl acetate, vinylethylene carbonate, dimethyl sulfite, fluoroethylene carbonate, trifluoropropylene carbonate, bromo gamma-butyrolactone, and fluoro gamma-butyrolactone.

9. The electrolyte of claim 2 further comprising an additive comprising at least one member selected from the group consisting of boron, phosphorous, sulfur, fluorine and carbon.

10. The electrolyte of claim 2 further comprising an additive, wherein said additive comprises at least one member selected from the group consisting of lithium hexafluorophosphate (LiPF₆), lithium bis-oxalatoborate (LiBOB), or other chelatoborate salt, lithium perchlorate (LiClO₄), lithium hexafluoroarsenate (LiAsF₆), lithium trifluoromethanesulfonate (LiCF₃SO₃), lithium trifluoromethanesulfonimide (Li(CF₃SO₂)₂N, lithium tetrafluoroborate (LiBF₄), lithium tetrachloroaluminate (LiClO4), lithium hexafluoroantimonate (LiSbF₆), CO₂, phosphate esters, borate esters, and water.

11. A cell comprising a positive electrode, a negative electrode and an electrolyte having a second cycle reduction current at 0.3 V vs Li/Li⁻

that is less than that of the first cycle, said electrolyte comprising a salt, which is not reduced above 0.3 V vs Li/Li⁺ and/or will not electrochemically passivate.

12. The cell of claim 11, wherein during said formation cycle of said cell, said cell is overcharged.

13. The cell of claim 11 wherein said cell further comprises an additive that forms a passivation layer on at least one of said electrodes.

14. The cell of claim 12 wherein said cell further comprises at least one additive that forms a passivation layer on at least one of said electrodes.

15. The cell of claim 12 wherein said additive comprises at least one inorganic compound.

16. The cell of claim 12 wherein said additive comprises at least one member selected from the group consisting of boron, phosphorous, sulfur, fluorine and carbon.

17. The cell of claim 12 wherein said additive comprises at least one member selected from the group consisting of selected from the group consisting of lithium hexafluorophosphate (LiPF₆), lithium bis-oxalatoborate (LiBOB), or other chelatoborate salt, lithium perchlorate (LiClO₄), lithium hexafluoroarsenate (LiAsF₆), lithium trifluoromethanesulfonate (Li(CF₃SO₃), lithium trifluoromethanesulfonimide (Li(CF₃SO₂)₂N, lithium tetrafluoroborate (LiBF₄), lithium tetrachloroaluminate (LiClO4), lithium hexafluoroantimonate (LiSbF₆), CO₂, phosphate esters, borate esters, and water.

18. The cell of claim 13 wherein said additive comprises at least one organic compound wherein said additive is selected from the group consisting of carbonates, chloroethylene carbonate, vinylene carbonate, vinylethylenecarbonate, sulftes, ethylene sulfite, propane sulfone, propylene sulfite, butyrolactones, phenylethylene carbonate, phenylvinylene carbonate, catechol carbonate, vinyl acetate, vinylethylene carbonate, dimethyl sulfite, fluoroethylene carbonate, trifluoropropylene carbonate, bromo gamma-butyrolactone, and fluoro gamma-butyrolactone.

19. The cell of claim 12 wherein said additive comprises at least one member selected from the group consisting of lithium hexafluorophosphate (LiPF₆), lithium bis-oxalatoborate (LiBOB), or other chelatoborate salt, lithium perchlorate (LiClO₄), lithium hexafluoroarsenate (LiAsF₆), lithium trifluoromethanesulfonate (LiCF₃SO₃), lithium trifluoromethanesulfonimide (Li(CF₃SO₂)₂N, lithium tetrafluoroborate (LiBF₄), lithium tetrachloroaluminate (LiClO4), lithium hexafluoroantimonate (LiSbF₆), CO₂, phosphate esters, borate esters, and water.

21. The method of claim 14, wherein said cell further comprises an additive to form a passivation layer on at least one of said electrodes.

25. The cell of claim 11 wherein the positive electrode comprises at least one member selected from the group consisting of iron phosphates and spinels.

26. The cell of claim 25 wherein the positive electrode comprises iron phosphate.

20. A method of forming an SEI layer in a cell comprising a positive electrode, a negative electrode and an electrolyte, said method comprising the step of overcharging said cell during the formation cycle.

22. A cell comprising a salt of the formula:

Li_aQ

where Q is a borate cluster anion or heteroborate cluster anion, and a is 1 or 2, wherein said cell undergoes a formation cycle comprising an overcharge step.

23. A cell comprising a salt of the formula:

Li_aQ

where Q is a borate cluster anion or heteroborate cluster anion, and a is 1 or 2, further comprising an additive.

24. An electrolyte comprising a salt of the formula:

Li_aQ

where Q is a borate cluster anion or heteroborate cluster anion, and a is 1 or 2, and at least one partially oxidized compound.