Elucidating the conductivity enhancement effect of nano-sized SnO 2 fillers in the hybrid polymer electrolyte PEO–SnO 2–LiClO 4

Abstract

Uniform SnO 2 nanoparticles were synthesized hydrothermally and calcined at elevated temperatures to obtain samples of different sizes, shapes and surface states. XPS and near-IR spectroscopy data prove that there exist a large amount of oxygen vacancies or interstitial Sn atoms on the SnO 2 nanoparticle surface. The incorporation of these SnO 2 particles into polyethylene oxide (PEO)–LiClO 4 composite through sonicating dispersion and annealing in vacuum renders the latter amorphous and more conductive. The calcined SnO 2 samples, which have higher oxygen vacancy concentrations, exhibit stronger conductivity enhancement effect in the hybrid polymer electrolyte (HPE). Therefore, the oxygen vacancies on SnO 2 surface were regarded as the active Lewis acidic sites that interact with both PEO segments and ClO 4 − ions leading to conductivity improvement.