TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: (a) and (b) are different; in (a) Mn+ is a cation of an alkali, alkaline earth, transition, rare earth, group IIB or group IIIB metal or a tetraalkylammonium, preferably Na+, Ca2+, Ba2+, Al3+, Eu3+, Sm3+, (C2H5)4N+ and (CH3)4N+, especially Li+; (a) is especially (C8F17SO2)N-(SO2CF3)Li+, (C4F9SO2)2N-Li+, (C8F17SO2)2N-Li+, (C8F17SO2)N-(SO2C4F9)Li+, or (C4F9SO2)N-(SO2CF3)Li+;in (a) the anion is NO3-, Br-, I-, BF4-, PF6-, AsF6-, ClO4-, SbF6-.(b) is lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium trifluoromethylsulfonate, lithium tris(trifluoromethane- sulfonyl)methide, or their mixture.Rf is 4 - 12 C and Rf' is 1 - 8 C perfluoroalkyl. Rf + Rf' is as least 8 C and preferably Rf' is at least 8 C.Preferred Composition: Molar ratio of (a)/(b) is 99:1 - 90:10. Matrix material is selected such that concentration of (a) in the electrolyte is 0.5 - 1.5 moles/L and that of (b) is 10 - 100 mM/L.Preferred Anion: In (a) is Rf0SO3- in which Rf0 is a 1 - 12 C perfluoroalkyl, (Rf1SO2)Rf2SO2)N)-, Rf4Rf5N(CH2)nSO2X, Rf6Rf7N(CF2)nSO2X, a bisfluoroarylsulfonyl methide RfIISO2C-RSO2RfIII, tri(perfluoroalkylsulfonyl) methide C(RfIISO2)(SO2RfIII)(SO2RfIV) or of formula (II):Rf1, Rf2 = 1 - 12 C perfluoroalkyl;Rf3 = 2 - 4 C perfluoroalkylene optionally substituted with 1 - 2 C perfluoroalkyl totaling not more than 4 C;X = -O-, -N-SO2Rf4, C-(Rf6SO2)(Rf7SO2);Z = -CF2-, -O-, -NRf8-, -SF4-,Rf4, Rf5 = -CmF2m+1, -(CF2)4SO2X', Rf1Rf2N(CF2)n-, Rf6Rf7N(CF2)n-;Rf6, Rf7 = -CF2r-Rf8 = -CmF2m+1, -(CF2)qSO2X',n = 1 - 4;m = 1 - 12;q = 1 - 4;RfII, RfIII, RfIV = 1 - 12 C perfluoroalkyl;X' = H, Br, Cl, I, 1 - 20 C aryl or alkaryl.Preferred Product: The is a (rechargeable) battery preferably comprising a lithium intercalated carbon anode and a metal oxide cathode. EXAMPLE - Wetting ability of 3 fluorinated imide surfactant salts, namely (C8F17SO2)N-(SO2CF3)Li+ (I), (C4F9SO2)N-(SO2C4F9)Li+ (II) and (C4F9SO2)N-(SO2CF3)Li+ (III), was assessed by dissolving each salt at 1 molar concentration in a 50/50 propylene carbonate/ethylene carbonate blend, then applying the liquid electrolyte so formed to a polyethylene and a polypropylene separator surface. Contact angles, measured initially and after 500 seconds, were as follows: 47, 0 (I); 47, 0 (II) and 41, 0 respectively for polyethylene and 47, 39 (I); 59, 56 (II) and 76, 69 (III). This compared to respective figures of 67, 65 (polyethylene) and 76, 76 (polypropylene) for an imide salt with only 4 carbon atoms its combined perfluorinated chain ((C2F5SO2)N-(SO2C2F3)Li+).