Effect of morphology and particle size on the ionic conductivities of composite solid electrolytes

Materón

et al. 2008

We report on electrical relaxation measurements of (1 − x)NH 4 H 2 PO 4 -xTiO 2 (x = 0.1) composites by admittance spectroscopy, in the 40-Hz-5-MHz frequency range and at temperatures between 303 and 563 K. Simultaneous thermal and electrical measurements on the composites identify a stable crystalline phase between 373 and 463 K. The real part of the conductivity, σ ', shows a power-law frequency dependence below 523 K, which is well described by Jonscher's expression σ = σ 0 (1 + (ω/ω p ) n ), where σ 0 is the dc conductivity, ω p /2π = f p is a characteristic relaxation frequency, and n is a fractional exponent between 0 and 1. Both σ 0 and f p are thermally activated with nearly the same activation energy in the II region, indicating that the dispersive conductivity originates from the migration of protons. However, activation energies decrease from 0.55 to 0.35 eV and n increases toward 1.0, as the concentration of TiO 2 nanoparticles increases, thus, enhancing cooperative correlation among moving ions. The highest dc conductivity is obtained for the composite x = 0.05 concentration, with values above room temperature about three orders of magnitude higher than that of crystalline NH 4 H 2 PO 4 (ADP), reaching values on the order of 0.1 ( cm) −1 above 543 K.

Section: Introductionmentioning

confidence: 99%

Electrical relaxation in proton conductor composites based on (NH4)H2PO4/TiO2

Materón

et al. 2008

“…2e, f), the large sphere-shaped domains of PAN are split into irregular, smaller sized domains resulting in the loss of spherical shapes. These dispersed irregular domains clearly indicate the miscibility of polymer, salt, and the plasticizers thereby indicating a homogeneous phase for the polymer electrolytes, which results in better conductivity enhancement [13].…”

Section: Preparation Of Pan-based Polymer Electrolytesmentioning

confidence: 99%

Conductivity study of some polymer electrolytes based on polyacrylonitrile

Borah

Dutta

2009

The present paper deals with the room temperature conductivity study of some polymer electrolytes based on polyacrylonitrile, ammonium tetraflouroborate as dopant, and propylene carbonate (PC) and polyethylene glycols (PEG300 and PEG600) as plasticizers. The additions of plasticizers having different dielectric constant have been found to modify the conductivity of polymer electrolytes. The increase in room temperature conductivity with plasticizer addition has been found to depend upon (1) the amount of salt present and (2) amount of plasticizers added. The polymer electrolytes prepared were characterized by Xray diffraction, scanning electron micrographs, infrared, thermogravimetric, and AC impedance measurements. The highest room temperature conductivity observed in case of these polymer electrolytes was ∼10-13 s/cm.

“…Ionic contribution to the total conductivity was determined by measuring ionic transference number (t~o,) using Wagner's dc polarization technique [15]. The results are discussed in the light of models suggested for the twophase composite electrolyte systems [1][2][3][16][17][18][19]. Discharge characteristics were studied under different load conditions on the solid state batteries fabricated by sandwiching OCC (electrolyte) between Ag-metal (anode) and mixtures of graphite & elemental/chelated iodine (cathode).…”

Section: Introductionmentioning

confidence: 99%

Transport properties and battery discharge characteristics of the Ag+ ion conducting composite electrolyte system (1−x)[0.75AgI: 0.25AgCl]: xFe2O3

Agrawal

Gupta

Sinha

et al. 2004

Abstract. Ion transport and battery discharge characteristic studies are reported for a new Ag + ion conducting two-phase composite electrolyte system (1-x)[0.75AgI: 0.25AgC1]: xFe203, where 0 < x < 0.5 in molar weight fraction. An alternative single-phase host-matrix 'annealed [0.75AgI: 0.25AgC1] mixed system/solid solution' has been used in place of the traditional host, AgI. Submicron size particles (< 1 gm) of Fe203 has been used as second phase dispersoid. The composition 0.8[0.75Agi: 0.25AgC1]: 0.2Fe:O3, exhibiting the highest room temperature conductivity has been refened to as the optimum conducting composition (OCC). The reason for an enhancement of an order of magnitude in the conductivity from that of the pure host has been identified through direct determination of ionic mobility (g) and mobile ion concentration (n) using transient ionic current (TIC) technique. The XRD study confirmed the coexistence of the constituent phases. The ionic transference number is found to be very close to unity. This reveals the fact that the silver ions are the sole charge carriers in the system. The results are discussed in the light of space-charge models proposed for the two-phase composite electrolyte systems. Solid state batteries, fabricated using OCC as electrolyte, Ag-metal as anode and mixtures of iodine & graphite, viz. (C+I2), (C+KI3), (C+(CH3)4NI3), (C+(C2Hs)gNI3), etc. as cathodes, were discharged under different load conditions. The battery with (C+I2) cathode performed satisfactorily specially under low current drain states.