Glass Transition and Relaxation Processes of Nanocomposite Polymer Electrolytes

Abstract

This study focus on the effect of δ-Al(2)O(3) nanofillers on the dc-conductivity, glass transition, and dielectric relaxations in the polymer electrolyte (PEO)(4):LiClO(4). The results show that there are three dielectric relaxation processes, α, β, and γ, in the systems, although the structural α-relaxation is hidden in the strong conductivity contribution and could therefore not be directly observed. However, by comparing an enhanced dc-conductivity, by approximately 2 orders of magnitude with 4 wt % δ-Al(2)O(3) added, with a decrease in calorimetric glass transition temperature, we are able to conclude that the dc-conductivity is directly coupled to the hidden α-relaxation, even in the presence of nanofillers (at least in the case of δ-Al(2)O(3) nanofillers at concentrations up to 4 wt %). This filler induced speeding up of the segmental polymer dynamics, i.e., the α-relaxation, can be explained by the nonattractive nature of the polymer-filler interactions, which enhance the "free volume" and mobility of polymer segments in the vicinity of filler surfaces.

The effects of SiO 2 and TiO 2 nanofillers on structural and electrochemical properties of poly(ethylene oxide)–EMIHSO 4 electrolytes

“…At below the transition at 1 kHz, the motion of ions assisted by long-range movement of polymer chains promoted ionic conductivity and contributed to electrode polarization. In accordance with Figure 4, the dielectric relaxation at 1 to 3 kHz can be ascribed to a transition state between a confined mobility of charge carriers at high frequenciesand ionic conduction over longer distances at low frequencies [43]. At lower frequencies, the conducting ions had more time to polarize at the electrode and completed EP at frequencies between 0.1 and 1 Hz.…”

“…easing the motion of polymer chains in amorphous regions [43]. The higher ε der in EP region in Figure 6 is the result of an increased ionic mobility or dissociation as temperature increased [44].…”

Novel poly(vinylidene fluoride-trifluoroethylene)/poly(ethylene oxide) blends for battery separators in lithium-ion applications

“…The room temperature ionic conductivity of the blends (Table 1) increases with the inclusion of PEO due the higher d.c. conductivity contribution and the dipoleorientation relaxation process of PEO [20]. Without electrolyte uptake, the conductivity is larger for the blend samples with lower PEO contents due to the dispersion of illcrystallized PEO within the PVDF-TrFE matrix.…”

Physicochemical properties of poly(vinylidene fluoride-trifluoroethylene)/poly(ethylene oxide) blend membranes for lithium ion battery applications: Influence of poly(ethylene oxide) molecular weight

“…8 [70]. The width of the semicircle in the charge transfer process represents the bulk resistance of the polymer blend and it increases with increasing PEO content in the P(VDF-TrFE)/PEO blend due to the higher d.c. conductivity contribution and the dipoleorientation relaxation process of PEO [71]. Fig.…”