Heterocyclic sulfonyl fluoride additives for electrolyte composition for lithium batteries An electrolyte composition containing •(i) at least one aprotic organic solvent; •(ii) at least one conducting salt; •(iii) at least one compound of formula (I) wherein R1, R2, and R3 are each independently H or a C1-C20 hydrocarbon group which may be unsubstituted or substituted by one or more substituents selected from F, CN, OS(O)2F, and S(O)2F and which may contain one or more groups selected from —O—, —S—, —C(O)O—, —OC(O)—, and —OS(O)2—; wherein at least one of R1, R2, and R3 is substituted by one or more S(O)2F groups; and •(iv) optionally one or more additives.