Solid Liquid Electrolyte Research Articles

Ion Transport and Structural Studies on a TEOS-Precursor Derived Silica Alcogel Doped with Acid H3PO4

Silica alcogels doped with proton conducting acid H 3 PO 4 have been prepared by the sol-gel process starting from organic precursor tetraethyl orthosilicate (TEOS). Structural (XRD, DTA/TGA, IR) and electrical (transference number, conductivity) studies showed that the solution of dopant remains entrapped in the porous SiO 2 -gel matrix and can be modelled as solid-liquid electrolyte composite. The H 3 PO 4 doped gels have been found to show about five orders higher protonic conductivity than the undoped SiO 2 -gel. The highest attainable room temperature conductivity 1.6 x 10 -2 S cm -1 is for the SiO 2 : H 3 PO 4 (40: 60) gel composite. The high liquid-like proton transport in this composite has been explained as a result of self dissociation of entrapped H 3 PO 4 or H 2 PO - 4 /HPO 2- 4 acid-base pair formation.

Porous silica alcogel matrix entrapped with liquid electrolyte: Ionic conductivity and growth of whiskers

Highly porous silica alcogel, with pores entrapped with liquid electrolyte solutions of KH 2PO 4, has been successfully prepared by hydrolysis and polycondensation of tetraethylorthosilicate (TEOS) giving interesting “solid-liquid electrolyte composites”. The entrapped liquid electrolyte solution gives high liquid-like ionic conductivity (∼10 −5 S·cm −1). Further, on storage the entrapped solution slowly reaches the surface pore-heads where it evaporates resulting in the growth of long crystalline whiskers. Higher relative humidity (>60%) slows down the evaporation and has been found to be favorable for whisker growth.

Photovoltaic devices based on polythiophenes and substituted polythiophenes

In recent years there has been considerable interest in the fabrication of photovoltaic devices using polymeric and organic materials. This paper presents work carried out using a range of polythiophenes, including some substituted with porphyrin moieties as light harvesters. Homopolymers and copolymers were investigated for their performance in photovoltaic devices, and the use of both solid polymer electrolyte and liquid electrolyte was examined. Both photoelectrochemical cells and Schottky devices were investigated. The best photoelectrochemical cell was fabricated using polyterthiophene which had V oc=139 mV, I sc=123.4 μA cm −2, fill factor=0.38, and energy conversion efficiency=0.02% at a halogen lamp intensity of 317 W m −2. The Schottky device gave a V oc=0.5 V and I sc of 0.98 μA cm −2 at a halogen lamp intensity of 500 W m −2.

Dynamic behaviour of an electrolyser with a two phase solid-liquid electrolyte Part II: Investigation of elementary phenomena and electrode modelling

The dynamic behaviour of an electrolyser with a two phase solid-liquid electrolyte was investigated. In a previous paper some results were obtained with high particle concentrations by means of spectral analysis of the electrolyte resistance fluctuations and of the potential fluctuations. Here low bead concentrations were used. This allows potential and electrolyte resistance transients to be well separated and to be studied in the time domain. This analysis gives a detailed view of the approach and residence of the beads near the collector, and a quantitative estimation of the ohmic drop effect for insulating and conductive beads. Ohmic drop fluctuations account for the potential fluctuations for insulating glass beads. Zinc beads behave as insulating particles in the low frequency range and generate a similar ohmic drop effect. They behave as conducting particles in the high frequency range and the fast charge exchange induces depolarizing pulses which favour the formation of compact zinc deposits on the current collector. From the analysis of both transients and PSDs of the electrolyte resistance and potential fluctuations, the mean percentage of the particles colliding with the collector has been estimated even for high bead concentrations.

Dynamic behaviour of an electrolyser with a two phase solid-liquid electrolyte Part I: Spectral analysis of potential fluctuations

The dynamic behaviour of a simplified electrolyser with a two phase solid-liquid electrolyte was investigated. The current-voltage curve and the impedance of the working electrode (current collector) was measured. In addition the fluctuations of the working electrode potential and of the electrolyte resistance close to the electrode were analysed, especially by spectral analysis. Conductive zinc-coated polystyrene beads and insulating glass beads were compared. For glass beads the kinetics were controlled by ohmic drop fluctuations due to the collisions of the beads onto the collector. With zinc beads the charge exchanges between the beads and the current collector were also observed and contributed to the potential fluctuations. A complementary analysis of the elementary potential and electrolyte resistance transients will be reported in Part II; the electrochemical behaviour of the collector will then be modelled.

Choice of a model for calculation and critical evaluation of solid-liquid electrolyte phase diagrams. Application to the ternary system NaCl-KCl-H2O

Abstract

Electrochemical processes at the interface between solid electrolyte and liquid electrolyte

The ac impedance of the interface between beta-alumina membrane and molten mixtures CO(NH 2) 2+NaI+I 2 or (C 4H 9) 4Ni+I 2 can be represented by parallel combination of a charge transfer resistance R F and Warburg impedance Z W =(1−j) Wω − 1 2 . The value of R F depends on electronic state of solid electrolyte. The Warburg impedance can be connected with slow diffusion of interstitial oxygen ions in the conducting planes between spinel blocks of beta-alumina.