Described are compounds of the structure R4-a—Si-((Sp-Y)—Zb)a, wherein “a” is an integer from 1 to 3; “b” is an integer from 0 to (3×a); “Z,” which is absent when “b”=0, is halogen, C1-6 linear or branched alkyl, alkenyl, or alkynyl, C1-6 linear or branched halo-alkyl, halo-alkenyl, or halo-alkynyl, or wherein each “R” is halogen, C1-6 linear or branched alkyl, alkenyl, or alkynyl or C1-6 linear or branched halo-alkyl, halo-alkenyl, or halo-alkynyl; each “Sp” C1-15 linear or branched alkylenyl or C1-15 linear or branched halo-alkylenyl; and each “Y” an organic polar group. Also described are electrolyte compositions containing one or more of these compounds.