TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compositions: Oxiranyl derivative contains greater than or equal to 2 oxirane cycles. Aprotic organic solvent is selected from (a) cyclic and non-cyclic organic carbonates, which may be partly halogenated; (b) di-(1-10C)-alkylethers which may be partly halogenated; (c) di-(1-4C)-alkyl-(2-6C)-alkylene ethers and polyethers which may be partly halogenated; (d) cyclic ethers which may be partly halogenated; (e) cyclic and acyclic acetals and ketals which may be partly halogenated; (f) orthocarboxylic acids esters which may be partly halogenated; (g) cyclic and non-cyclic esters of carboxylic acids which may be partly halogenated; (h) cyclic and non-cyclic sulfones which may be partly halogenated; (i) cyclic and non-cyclic nitriles and dinitriles which may be partly halogenated; and/or (j) ionic liquids which may be partly halogenated. Conducting salt is selected from Li(F6-xP(CyF2+1)x), Li(B(R9)4), Li(B(R9)2(OR10O)), Li(B(OR10O)2), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium hexafluorosilicate (Li2SiF6), lithium hexafluoroantimonate (LiSbF6), lithium tetrachloroaluminate (LiAlCl4), lithium bis-(fluorosulfonyl) imide (Li(N(SO2F)2)), lithium tetrafluoro(oxalato) phosphate, lithium oxalate, and/or salts of formula Li(Z(CnF2n+1SO2)m). The additive is vinylene carbonate (derivatives), vinyl ethylene carbonate (derivatives), methyl ethylene carbonate (derivatives), lithium (bisoxalato) borate, lithium difluoro(oxalato) borate, lithium tetrafluoro(oxalato) phosphate, lithium oxalate, 2-vinyl pyridine, 4-vinyl pyridine, cyclic exo-methylene carbonates, sultones, organic esters of inorganic acids, acyclic and cyclic alkanes having boiling point at 1 bar of greater than or equal to 36 degrees C, aromatic compounds, optionally halogenated cyclic and acyclic sulfonylimides, optionally halogenated cyclic and acyclic phosphate esters, optionally halogenated cyclic and acyclic phosphines, optionally halogenated cyclic and acyclic phosphites, optionally halogenated cyclic and acyclic phosphazenes, optionally halogenated cyclic and acyclic, silylamines, optionally halogenated cyclic and acyclic halogenated esters, optionally halogenated cyclic and acyclic amides, optionally halogenated cyclic and acyclic anhydrides, ionic liquids, and/or optionally halogenated organic heterocycles. Concentration of oxiranyl derivative is 0.001-10 wt.% based on the total weight of electrolyte composition.x=0-6;y=1-20;R9=F, Cl, Br, I, 1-4C alkyl, 2-4C alkenyl, or 2-4C alkynyl provided that alkyl, alkenyl, and alkynyl are optionally substituted by OR11;R11=1-6C alkyl, 2-6C alkenyl, or 2-6C alkynyl;(OR10O)=bivalent group derived from 1,2- or 1,3-diol, 1,2- or 1,3-dicarboxlic acid, or 1,2- or 1,3-hydroxycarboxylic acid in which bivalent group forms a 5- or 6-membered cycle via both O-atoms with central B-atom;m=1 provided that Z is O or S;m=2 provided that Z is N or P;m=3 provided that Z is C or Si; andn=1-20.