Ionic Transport Properties of P2O5-SiO2 Glassy Protonic Composites Doped with Polymer and Inorganic Titanium-based Fillers

Abstract

<jats:p>This paper is focused on the determination of the physicochemical properties of a composite inorganic–organic modified membrane. The electrical conductivity of a family of glassy protonic electrolytes defined by the general formula (P2O5)x(SiO2)y, where x/y is 3/7 are studied by Alternating Current electrochemical impedance spectroscopy (AC EIS) method. The reference glass was doped with polymeric additives—poly(ethylene oxide) (PEO) and poly(vinyl alcohol) (PVA), and additionally with a titanium-oxide-based filler. Special attention was paid to determination of the transport properties of the materials thus modified in relation to the charge transfer phenomena occurring within them. The electrical conductivities of the ‘dry’ material ranged from 10−4 to 10−9 S/cm, whereas for ‘wet’ samples the values were ~10−3 S/cm. The additives also modified the pore space of the samples. The pore distribution and specific surface of the modified glassy systems exhibited variation with changes in electrolyte chemical composition. The mechanical properties of the samples were also examined. The Young’s modulus and Poisson’s ratio were determined by the continuous wave technique (CWT). Based on analysis of the dispersion of the dielectric losses, it was found that the composite samples exhibit mixed-type proton mobility with contributions related to both the bulk of the material and the surface of the pore space.</jats:p>

Transference Number Determination in Poor-Dissociated Low Dielectric Constant Lithium and Protonic Electrolytes

“…Consequently, the experiments devoted to the determination of their protonic transference numbers play only a limited role in the investigation of their transport properties. The opposite situation can be observed in protonically conductive systems based either on complexes of polymeric backbones with ammonium salts which, despite their practical applicability are studied for at least thirty years [18,19], or inorganic protonically conductive glasses based on poly (phosphoric acid) [20,21] where both protons and anions can be mobile, and therefore, determination of the protonic transference number value is valuable. Unfortunately, the methodology of such determination is not only significantly less developed in comparison with the lithium systems but, as well, inherently limited by the lack of proton reversible electrodes characterized with stable enough values of their potentials.…”

“…On the other hand, studying the literature one can find numerous papers claiming either single ion conductivity of the studied systems [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] or enhanced lithium-ion transport [29,30]. Moreover, in some publications, the transport properties of the polymeric electrolytes are addressed without the meaningful determination of the basic and most prominent charge transport characterizing parameter-cationic transference number.…”

Special Issue “Hydrogen Storage and Fuel Cells: Materials, Characterization and Applications”

“…Another type of membrane that is quite important and particularly studied in the literature is the class of composite membranes. In this work, the authors describe the synthesis methods and the chemical-physical and electrochemical characterizations performed on a phosphosilicate-based membrane with the formula 30P 2 O 5 -70SiO 2 , doped with poly (ethylene oxide) (PEO) and poly (vinyl alcohol) (PVA) using Ti oxide as an additive [6]. The synthesized samples were carefully characterized through Fourier transformed infrared spectroscopy (FTIR), FT-Raman spectroscopy; porosimetry and microstructure techniques through BET measurements; mechanical properties through dynamo-mechanical measurements; thermal analysis through differential thermal analysis (DTA) and thermogravimetry (TG); electrical and electrochemical measurements through electrical impedance spectroscopy (EIS) to alternating current measurements.…”