Single-ion-conducting nanocomposite polymer electrolytes based on PEG400 and anionic nanoparticles: Part 2. Electrical characterization

Molecular relaxation and polarization phenomena of twelve single-ion-conducting nanocomposite polymer electrolytes (nCPEs) are studied using Broadband Electrical Spectroscopy (BES). The electrolytes are obtained by combining PEG400 oligomers with increasing amounts of anionic nanofiller comprised of fluorinated-TiO2 associated with Li+ cations (LiFT®), resulting in [PEG400/(LiFT)y] systems with 0 ≤ y ≤ 26.4. This new class of [PEG400/(LiFT)y] electrolytes allows us to achieve a significant single-ion conductivity (1.1·10−5 S cm−1 at 30 °C for nLi/nO = 0.113) without the addition of lithium salts. To the best of our knowledge, this is the highest conductivity value reported for this class of electrolytes. This study, in conjunction with the results reported in Part 1, leads us to hypothesize a conduction mechanism in terms of two types of long-range charge-transfer processes. The first charge-transfer occurs at the interface between the filler nanoparticles and filler-PEG domains, while the second occurs through the PEG400 matrix with the assistance of polymer segmental motion. The measured Li+ transference numbers confirm that the studied materials are single-ion conductors.