Rechargeable Lithium-Ion Cell with Triphenylamine Redox Shuttle

Abstract

Provided is a rechargeable lithium-ion cell that contains a positive electrode, a negative electrode, a charge-carrying electrolyte containing a charge carrying medium and a lithium salt, and a triphenylamine compound dissolved in or dissolvable in the electrolyte. The triphenylamine compound has an oxidation potential above the positive electrode recharged potential and serves as a cyclable redox chemical shuttle providing cell overcharge protection. Also provided are methods for manufacturing a rechargeable lithium-ion cell.

Description

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1. is an exploded perspective schematic view of an electrochemical cell.

Claims

1. A rechargeable lithium-ion cell comprising: (a) a positive electrode having a recharged potential;(b) a negative electrode;(c) a charge-carrying electrolyte comprising a charge carrying medium and a lithium salt; and(d) a cyclable redox chemical shuttle comprising a fluorine-containing or chlorine-containing triphenylamine compound or a triphenylamine compound with a molecular weight greater than 500;wherein the chemical shuttle is dissolved in or dissolvable in the electrolyte and has an oxidation potential above the recharged potential of the positive electrode.

2. A cell according to claim 1 wherein the triphenylamine compound is substituted with one or more halogen or trihaloalkyl substituents.

3. A cell according to claim 2 wherein the one or more halogen groups are selected from fluoro, chloro, and bromo.

4. A cell according to claim 3 wherein each phenyl ring is substituted with an equal number of the same halogen.

5. A cell according to claim 1 wherein the negative electrode comprises graphitic carbon, lithium metal, or a lithium alloy compound.

6. A cell according to claim 1 wherein the cyclable redox chemical shuttle has the chemical formula:

7. The cell of claim 6 wherein R1 or R2 comprise one or more F or trifluoroalkyl groups.

8. The cell of claim 6 wherein R1 or R2 comprise one or more Br or tribromoalkyl groups.

9. A cell according to claim 1 wherein the triphenylamine compound comprises tris(4-fluorophenyl)amine, tris(4-trifluoromethylphenyl)amine, tris(2,4,6-trifluorophenyl)amine, tris(4-methyl-2,3,5,6-tetrafluorophenyl)amine, tris(2,3,5,6-tetrafluorophenyl)amine, tris(2,3,4,5,6-pentafluorophenyl)amine, tris(4-trifluoromethyl-2,3,5,6-tetrafluorophenyl)amine, tris(2,6-difluoro-4-bromophenyl)amine, tris(2,4,6-tribromophenyl)amine, tris(2,4,6-trichlorophenyl)amine, or mixtures thereof.

10. A cell according to claim 1 wherein the chemical shuttle is comprised of at least two compounds selected from tris(4-bromophenyl)amine, tris(4-fluorophenyl)amine, tris(4-trifluoromethylphenyl)amine, tris(2,4,6-trifluorophenyl)amine, tris(4-methyl-2,3,5,6-tetrafluorophenyl)amine, tris(2,3,5,6-tetrafluorophenyl)amine, tris(2,3,4,5,6-pentafluorophenyl)amine, tris(4-trifluoromethyl-2,3,5,6-tetrafluorophenyl)amine, tris(2,6-difluoro-4-bromophenyl)amine, tris(2,4,6-tribromophenyl)amine, tris(2,4,6-trichlorophenyl)amine, or a mixture thereof.

11. A cell according to claim 1 wherein the triphenylamine compound is dissolved in the electrolyte.

12. The cell of claim 11 wherein the charge carrying medium comprises a cosolvent.

13. A cell according to claim 12 wherein the cosolvent comprises ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, fluoroethylene carbonate, vinylene carbonate, vinylethylene carbonate, or a combination thereof.

14. A cell according to claim 1 wherein the triphenylamine compound has an oxidation potential from about 0.1 V to about 2.0 V above the recharged potential of the positive electrode.

15. A cell according to claim 1 wherein the triphenylamine compound has an oxidation potential from about 0.3 to about 0.6 V above the recharged potential of the positive electrode.

16. A cell according to claim 1 wherein the triphenylamine compound provides overcharge protection after at least 25 charge-discharge cycles at a charging voltage sufficient to oxidize the triphenylamine compound and at an overcharge charge flow equivalent to 100% of the cell capacity during each cycle.

17. A cell according to claim 1 wherein the triphenylamine compound provides overcharge protection after at least 40 charge-discharge cycles at a charging voltage sufficient to oxidize the triphenylamine compound and at an overcharge charge flow equivalent to 100% of the cell capacity during each cycle.

18. A cell according to claim 1 wherein the triphenylamine compound has a calculated binding energy to an ethyl radical, Eb(ER), of less than or equal to 1.8 eV.

19. A rechargeable lithium-ion cell comprising: (a) a positive electrode having a recharged potential;(b) a negative electrode comprising graphitic carbon, lithium metal, or a lithium alloy compound; and(c) a charge-carrying electrolyte comprising: (i) a charge-carrying media comprising ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, fluoroethylene carbonate, vinylene carbonate, vinylethylene carbonate, or a combination thereof;(ii) a lithium salt comprising LiPF6, lithium bis(oxalato)borate, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, or a combination thereof; and(iii) a cyclable redox chemical shuttle comprising a triphenylamine compound;wherein the positive electrode comprises LiFePO4, Li2FeSiO4, LiMn2O4, LiMnPO4, LixMnO2 (where x is about 0.3 to about 0.4), MnO2, LiVOPO4, Li3V2(PO4)3, LiV3O8, or LiVO(PO4)F; andwherein the chemical shuttle is dissolved in or dissolvable in the electrolyte and has an oxidation potential above the recharged potential of the positive electrode; andwherein the chemical shuttle is dissolved in or dissolvable in the electrolyte and has an oxidation potential above the recharged potential of the positive electrode.

20. A cell according to claim 19 wherein the triphenylamine compound comprises, triphenylamine, tris(4-bromophenyl)amine, tris(4-fluorophenyl)amine, tris(4-trifluoromethylphenyl)amine, tris(2,4,6-trifluorophenyl)amine, tris(4-methyl-2,3,5,6-tetrafluorophenyl)amine, tris(2,3,5,6-tetrafluorophenyl)amine, tris(2,3,4,5,6-pentafluorophenyl)amine, tris(4-trifluoromethyl-2,3,5,6-tetrafluorophenyl)amine, tris(2,6-difluoro-4-bromophenyl)amine, tris(2,4,6-tribromophenyl)amine, tris(2,4,6-trichlorophenyl)amine or mixtures thereof.

21. A method for manufacturing a rechargeable lithium-ion sealed cell comprising the steps of assembling in any order and enclosing in a suitable case: (a) a positive electrode having a recharged potential;(b) a negative electrode;(c) a charge-carrying electrolyte comprising charge carrying medium and lithium salt; and(d) a cyclable redox chemical shuttle comprising a fluorine-containing or a chlorine-containing triphenylamine compound or a triphenylamine compound with a molecular weight greater than 500;wherein the chemical shuttle is dissolved in or dissolvable in the electrolyte and has an oxidation potential above the recharged potential of the positive electrode.