Relation between structural and conductivity relaxation in PEO and PEO based electrolytes

Identification of relaxation processes in pure polyethylene oxide (PEO) films by the dielectric permittivity and electric modulus formalisms

“…For T < T g and high frequencies, the power‐law frequency ( ω −N )‐contribution by dc conduction and/or a series capacitance, created from interfacial/electrode polarization, to the as‐measured sample's ac‐impedance of Equation can be tolerated. Thus, the observed broad high‐frequency loss peaks are attributed to inherent dielectric process, which in pure PEO polymer is often assigned to γ ‐relaxtion prevailing at low temperatures below its T g . The γ ‐relaxtion in pure PEO polymer is related to local twisting of chain ends and local intramolecular twisting motion of its ethylene parts.…”

“…Not only the amorphous‐phase and crystalline‐phase regions in semicrystalline polymers, as PEO polymer, hinder their ionic conductivity and suppress dielectric relaxations but also interfacial barriers between amorphous and crystalline regions may alter their structural, conduction, and dynamical properties. Thus, it is essential to minimize crystallinity in PEO polymer and reduce amorphous‐crystalline interfacial barriers, besides simultaneously enhancing ionic conduction and dielectric relaxation in PEO films and PEO‐based electrolytes, a challenging task attempted by many researchers by using diverse routes …”

“…The relaxation behavior of semicrystalline pure PEO below its melting point T m often exhibits α‐, β‐, and γ‐relaxation processes . The α‐relaxation may be linked to local segmental motions of amorphous parts of main polymer chain of PEO material, and it is difficult to be observed and separated in the as‐measured loss spectra of pure PEO in the low‐frequency region and/or at high temperatures due to its high dc conductance and/or interfacial/electrode polarization effects in these frequency and temperature regimes.…”

“…The β‐relaxation process due to cooperative segmental motions in noncrystalline portion or in “interphase” between crystalline and amorphous segments of PEO polymer occurs at higher frequencies, while the γ‐relaxation process dominating at lower temperatures and high frequencies is assigned to local intramolecular twisting of main chains within crystallites and local motions in side‐group segments. These relaxation processes are affected by the crystallinity content of PEO sample, by its extrinsic additives and complexes, and by thermal treatment of the sample studied . Their identification and distinction from each other are difficult in pure PEO polymer unless one adopts a proper dielectric formalism to display the measured impedance/dielectric data over a wide range of temperatures and ac‐signal frequencies.…”

Synthesis of Li1.3Al0.3Ti1.7(PO4)3 films with nasicon structure by tаpe casting method

“…However, using of organic liquid or polymer electrolyte prevents the creation of completely safe device [4][5][6]. Replacement of the organic electrolyte with inorganic solid will not only significantly improve the safety of lithium-ion battery, but extend its life by reducing the degradation processes [7][8][9][10].…”