Patent ID: 6350546
Filing Date: 2002-02-26
Classification: H01M,Y02E

Abstract:
An electrochemical cell, which comprises:a) a negative electrode which intercalates with an alkali metal; b) a positive electrode comprising an electrode active material which intercalates with the alkali metal; c) a nonaqueous electrolyte including a quaternary, nonaqueous carbonate solvent mixture and activating the negative and the positive electrodes; and d) a sulfate additive provided in the electrolyte, wherein the sulfite additive has the general formula: R1OS(&boxH;O)2(OR2) and is selected from the group consisting of a silyl sulfate, a tin sulfate and an organic sulfate having at least one unsaturated hydrocarbon containing a C(sp2 or sp3)â€”C(sp3) bond unit having the C(sp3) carbon directly connected to the â€”OSO3â€” functional group and wherein R1 and R2 are the same or different and they can both be a hydrogen atom or an organic group containing 1 to 12 carbon atoms, and wherein at least R1 has the structure (R3) (R4) (R5)Câ€” if R2â‰ H with at least R3 being an aromatic substituent or an unsaturated organic or inorganic group and wherein if any of the remaining groups of R4 and R5 is a saturated organic group, the saturated organic group contains 1 to 11 carbon atoms.