The mechanism of conductivity of liquid polymer electrolytes

Conductivities and viscosities of solutions of Li, Na and K thiocyanates in low-molecular-weight liquid copolymers of ethylene oxide and propylene oxide have been measured. The curves of molar conductance vs. c½ show well defined maxima and minima. The conductivity is independent of copolymer molecular weight but is enhanced by raising the EO content of the copolymer. The results are interpreted in terms of a model in which the effects of ion association and re-dissociation play an important role. It is suggested that the characteristic properties of liquid polymer electrolytes can be satisfactorily explained only if the current is largely anionic.