TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The electrochemically active material comprises a lithium transition metal oxide. The partially fluorinated polymer additive is soluble to at least 5 wt.% in the liquid electrolyte. The lithium transition metal oxide comprises more than one transition metal, preferably cobalt, manganese and nickel.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The organic solvent comprises ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate and/or vinylene carbonate. The electrolyte salt comprises lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(oxalato)borate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(pentafluoroethanesufonyl)imide, lithium hexafluoroarsenate and/or lithium tris(trifluoromethylsulfonyl)methide.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The partially fluorinated polymer additive: is the product of polymerization of a monomer mixture that comprises vinylidene fluoride, hexafluoropropylene (both preferred) and tetrafluoroethylene; is the reaction product of vinylidene fluoride and hexafluoropropylene; comprises a substructure (-CF2-CH2-CF2-CF(CF3)-); is present in the liquid electrolyte at 0.2-2 wt.%; has a molecular weight of less than 50000 atomic mass units; and has the same structure as its fully hydrogenated analog with 10-90% of the hydrogen atoms of the fully hydrogenated analog replaced by fluorine substituents. The monomer mixture further comprises at least one of a fluorinated vinyl ether comonomer or a hydrocarbon comonomer. The fluorinated vinyl ether comonomer is 1,1,2-trifluoro-2-(trifluoromethoxy)ethylene, 1,1,1,2,2,3,3-heptafluoro-3-(1,2,2-trifluorovinyloxy)propane, 1-(difluoro(trifluoromethoxy)methoxy)-1,2,2-trifluoro-ethylene, 2,2-difluoro-2-(1,2,2-trifluorovinyloxy)acetonitrile, (difluoro(1,2,2-trifluorovinyloxy)methyl)sulfonyloxylithium, (2-(1-(difluoro(1,2,2-trifluorovinyloxy)methyl)-1,2,2,2-tetrafluoro-ethoxy)-1,1,2,2-tetrafluoro-ethyl)sulfonyloxylithium, or (2-(1,2,2-trifluorovinyloxy)acetyl)oxylithium. The hydrocarbon comonomer is ethylene or propylene.