Patent ID: 6699623
Filing Date: 2004-03-02
Classification: H01M,Y02E,Y02P,Y10T

Abstract:
A lithium-ion electrochemical cell, the cell comprising an anode comprising an anode active material, an anode current collector in electronically conductive contact with said anode; a cathode exhibiting an upper charging voltage in the range of 3 to 5 volts with respect to a Li/Li+ reference electrode, said cathode comprising a lithium insertion transition metal oxide, phosphate, or sulfate in electronically conductive contact with a graphite sheet cathode current collector, said graphite sheet cathode current collector being characterized by a purity of>95%, a thickness of less than 250 micrometers, a bulk density of 0.08-2.25 g/cc, an electrical conductivity of at least 500 Siemens/cm, and said electronically conductive contact being characterized by a resistance of less than 50 ohm-cm2; an ion-permeable membrane as a separator between said cathode and anode; and an electrolyte solution being in ionically conductive contact with said anode and cathode, the electrolyte solution comprising an aprotic polar solvent or a polymer, and a lithium compound at a concentration in the range of 0.2 up to 3 molar, said lithium compound being represented by the formulaRf1SO2Xâˆ’(Li+)YZa wherein X is C or N, a=0 or 1 with the proviso that a=1 when X is C and a=0 when X is N; wherein when a=1, Y and Z independently are electron-withdrawing groups selected from the group consisting of CN, SO2Rf2, SO2R, P(O)(OR)2, CO2R, P(O)R2, C(O)Rf3, C(O)R, cycloalkenyl groups formed therewith, and, H, with the proviso that Y and Z cannot both be H; wherein further Rf1, Rf2 and Rf3 are perfluoroalky radicals of 1-4 carbons optionally substituted with one or more ether oxygens; R is an alkyl group of 1-6 carbons optionally substituted with one or more ether oxygens, or an aryl group optionally further substituted; or wherein, when a=0, Y is an electron-withdrawing group represented by the formula â€”SO2Rf6 where Rf6 is the radical represented by the formula â€”(Rf4SO2Nâˆ’(Li+)SO2)mRf5 where m=0 or 1, and Rf4 is â€”CnF2nâ€” and Rf5 is â€”CnF2n+1 where n=1-4, optionally substituted with one or more ether oxygens.