TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The linear carbonate-based solvent is selected from dimethylcarbonate, diethylcarbonate, and/or ethylmethylcarbonate. The ammonium cation is selected from pyridinium ions, pyradizinium ions, pyrimidinium ions, pyrazinium ions, imidazolium ions, pyrazolium ions, thiazolium ions, oxazolium ions, and/or triazolium ions. The ammonium cation is selected from cations of formulae (I), (II), and/or R7-(R8)N+(R10)-R9 (III).R1, R2, R5-R10=1-30C alkyl substituted with greater than or equal to 1 1-30C alkoxy, 1-30C alkyl substituted with greater than or equal to 1 COOH, unsubstituted 1-30C alkyl, 1-30C alkoxy substituted with greater than or equal to 1 1-30C alkoxy, 1-30C alkoxy substituted with greater than or equal to 1 COOH, or unsubstituted 1-30C alkoxy;R3, R4=H, 1-30C alkyl substituted with greater than or equal to 1 1-30C alkoxy, 1-30C alkyl substituted with greater than or equal to 1 COOH, or unsubstituted 1-30C alkyl;n=1-4 or 1-3;andm=0 or 1.The electrolyte further comprises anion(s). The ammonium cation and anion are provided in an ionic solution, which is present in the electrolyte at 20-70 wt.%. The anion is selected from dimesyl imide (N(SO2CH3)2-); bis(pentafluoroethylsulfonyl) imide (N(SO2CF2CF3)2-); hexafluorophosphate (PF6-); boron tetrafluoride (BF4-); or anions of formulae (III) and/or (IV). The oxalatoborate-based additive is of formula (V).R11, R12=halo or 1-10C halogenated alkyl.The oxalatoborate-based additive is lithium difluorooxalatoborate or lithium bisoxalatoborate. It is present at 0.1-5 wt.%. The phosphoric acid-based solvent is selected from phosphates, phosphonates, and/or phosphazenes. It is present at 5-30 wt.%. The electrolyte further comprises fluorinated carbonate-based solvent selected from fluoroethylene carbonate, difluoroethylene carbonate, fluorodimethyl carbonate, and/or fluoroethylmethyl carbonate. The fluorinated carbonate-based solvent is present at 10-50 wt.%.    TECHNOLOGY FOCUS - POLYMERS - Preferred Component: The rechargeable lithium battery further comprises a coating on the negative electrode, where coating comprises a polymer derived from oxalatoborate-based additive; or a material selected from lithium fluoride and/or oxalatoborate-based polymer. The coating comprises a polymer of formula -O-C(=O)-C(=O)-O-B(O-C(=O)-C(=O)-O-)-O-C(=O)-C(=O)-O-B(O-C(=O)-C(=O)-O-)-O-C(=O)-C(=O)-O-. EXAMPLE - Flame retardant electrolyte solution was prepared from (wt.%) 1 M lithium phosphorus hexafluoride (9), dimethyl carbonate (50), ionic solution (20) including ammonium cations of formula H3C-(H3C)N+(CH3)-CH2-O-CH3-SO2CF3-N--SO2CF3, trimethyl phosphate (10), lithium difluorooxalatoborate (1), and fluoroethylene carbonate (10). The resulting electrolyte solution had a viscosity of less than or equal to 5 cP and showed excellent retardancy. The rechargeable lithium cell prepared with the resulting electrolyte had charge capacity of 360 mA-hour/g, discharge capacity of 337 mA-hour/g, formation efficiency of 94%, and capacity retention of 97.1%.