Ion transport in some solid state proton conducting composites studied from volta cell e.m.f. and complex impedance spectroscopy

Abstract

Proton conducting composites of heteropolyacid hydrates (phosphomolybdic acid H 3 PMo 12 O 40 ⋅ ⋅nH 2 O, PMA; phosphotungstic acid H 3 PW 12 O 40 ⋅ ⋅nH 2 O, PTA) and salt hydrate like NiCl 2 ⋅ ⋅6H 2 O were prepared with insulating Al 2 O 3 as dispersoid. The ionic conductivity peaks at two concentrations of Al 2 O 3 indicating two percolation thresholds for proton conduction. Two separate experiments were carried out to check the existence of such percolation thresholds viz. the volta battery experiment involving the measurement of e.m.f. of an electrochemical cell with composites of different compositions used as electrolyte and the composition vs conductivity measured by the complex impedance spectroscopy. The presence of two maxima has been attributed to two different percolation thresholds for the two possible mobile protonic species H + (H 3 O +) and OHarising from the hydrates.

Stable and Efficient Dye-Sensitized Solar Cells and Supercapacitors Developed Using Ionic-Liquid-Doped Biopolymer Electrolytes

“…In KIBPEs, we have achieved the conductivity maxima at 50 weights % concentration of KI with a conductivity value of 1.50 × 10 −4 S/cm ( Figure 1 a), whereas in ILBPEs, we achieved the highest conductivity at 8 weight % concentration of IL with a conductivity value of 3.10 × 10 −3 S/cm ( Figure 1 b). Single maxima as well as double maxima in dispersed polymer electrolyte systems have already been cited in the literature, where conductivity enhancements are due to additional charge carriers; lower maxima indicate the formation of charge pair ions [ 32 , 33 ]. Maximum conducting ILBPEs were sandwiched between the electrodes to fabricate EDLCs and DSSCs.…”

Ionic liquid (1-hexyl-3-methylimidazolium iodide)-incorporated biopolymer electrolyte for efficient supercapacitor

“…9 However polymer electrolyte systems with two maxima are rather scanty. Lakshmi and Chandra 3 reported two maxima in an ion-conducting system where first maxima are defined by cation while second maxima are associated with anions.…”

“…Energy can be stored in many ways, namely electrochemically (battery, fuel cells), mechanically (flywheels, springs, hydraulic accumulators), thermally (molten salts, steam, bodies of water), electrically (supercapacitors) and many more. 1 –7 A supercapacitor was one of the revolutionary achievements for meeting alarming energy demands as bridges the gap between rechargeable batteries and capacitors. It has positive points from both capacitor and batteries, thus, is more beneficial and useful.…”