Perfluoropolyether additives for electrochemical applications

Electrolytic compositions comprising a perfluoropolyether additive of formula (I): wherein: d,e,f are integers; a,b,c can be zero or integers; being a+b+ c+d+e+f such that the number average molecular weight ranges from 500 to 5x10; T are end groups -CF2X (X=F,CF,Cl), -CF, -CF(CF)COO (1/n)M, -CFCOO (1/n)M,-CFC(O(1/n)M)CF; M is a cation having valence n=1-4.