TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The aromatic phosphorus compound is of formula (a), (b) or (c), preferably (3,5-bis-(diethoxy-phosphorylmethyl)-2,4,6-trimethyl-benzyl)-phosphonic acid diethyl ester or (2-(diisopropoxy-phosphorylmethyl)-benzyl)-phosphonic acid diisopropyl ester. (I) contains at least two aromatic phosphorus compounds (a). (I) further comprises at least one phosphorus-sulfur compound of formula ((R5-(X1a)m)2-P(=X)-T)n-A1a). The solvent includes at least one material comprising linear alkyl carbonates, cyclic carbonates, esters, alkyl ethers, nitriles, sulfones, sulfolanes, siloxanes or sultones, where the solvent includes at least one linear alkyl carbonate and/or at least one cyclic carbonate. The lithium salt is at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium trifluoro methanesulfonate or lithium bis(trifluoromethyl sulfonyl)imide. (I) further comprises: at least one other additive comprising a solid electrolyte interface formation promoter, cathode protection agent, lithium salt stabilizer, lithium deposition improving agent, ionic solvation enhancer, corrosion inhibitor, wetting agent or viscosity reducing agent; at least one carbonate compound having aliphatic C-C unsaturation; and at least one sultone compound.R3 = H, 1-3C alkyl (preferred), OH, halo, 1-3C alkoxy or 2-3C alkylene;R4 = 1-8C alkyl (preferred) or 1-8C alkylene, preferably methyl, ethyl or isopropyl;X, X1a = O or S;T = covalent bond, O or S;m = 0-1 (when X1a is O) or 0-2 (when X1a is S, n is at least 1, preferably at least 2); eitherR5 = hydrocarbyl (optionally substituted); orR5R5 = divalent organic group (optionally substituted); andA1a = organic linking group.Provided that at least one of X and T is S. EXAMPLE - Typical battery electrolyte solution comprised of: lithium hexafluorophosphate (1 M in a 50/50 by volume mixture of ethylene carbonate and diethyl carbonate); and (3,5-bis-(diethoxy-phosphorylmethyl)-2,4,6-trimethyl-benzyl)-phosphonic acid diethyl ester (5 wt.%).