Estimation of Li+ transport number in polymer electrolytes by the combination of complex impedance and potentiostatic polarization measurements

The Li+ transport numbers of two types of polymer electrolytes have been estimated by means of the combination of the complex impedance and potentiostatic polarization measurements. Type I electrolytes were the network polymers with dissolved LiClO4 obtained from poly (ethylene oxide) (PEO) and from PEO-grafted-polydimethylsiloxane. Type II electrolyte was the network polymer obtained from PEO where -COO−Li+ groups were linked to the polymer backbone by covalent bonds. The ionic conductivity and Li+ transport number well reflected the differences in the polymer structures. The type I electrolytes had higher conductivities than the type II electrolyte, whereas the Li+ transport numbers were considerably lower than unity. In contrast, the type II electrolyte had the Li+ transport number of unity.