Electrochemical studies of water insertion and proton – Ceramic interaction in substituted perovskite SrZr 0.9 Ln 0.1 O 2.95

Abstract

Because of their high ionic conduction even at relatively low temperatures, proton conducting ceramics are one of the most promising electrolytes for fuel cell. In contrast to oxide-ion conductors, proton-conducting systems, especially in an electrolyser plant, could operate below 600°C, critical temperature for mechanical and hot corrosion resistance of common stainless steels. Proton conduction in perovskite type ceramic was analyzed under the water molecules insertion to maximize proton conduction. To this end, the SrZr 0.9 Ln 0.1 O 2.95 electrolyte and its microstructure, particularly grain size was investigated. The insertion and release of water in the perovskite structure was followed by impedance spectroscopy and by using the so-called Brick Layer Model (BLM) to separate the bulk and grain boundary conductivities. It was found that the conductivity in both zones increases namely with steam pressure. It was also verified that the bulk conductivity is higher than that of grain boundaries. Consequently both the operating steam pressure and the grain size appear as the main parameters that can be tuned to enhance the proton conduction.

Surface Reactivity of YSZ, Y2O3, and ZrO2toward CO, CO2, and CH4: A Comparative Discussion

“…Of course, another possibility is simply that there are many different processes occurring simultaneously, which can be better separated on the other samples. Numerous attempts [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] have been made in order to find the most adequate fit for an ionic conductor such as YSZ. However, several obstacles have to be overcome in order to find the perfect fit model: grain size effects 45,46,53,54,57,59,60 or the semicircles being a mixture of the involved processes, to name just a few.…”

“…The agreement of the simulated spectra with the experimental data supports the validity of the equivalent circuit diagram and also the comparison to other studies on and under similar materials and conditions. 3,37,42,46,50,54,56,59,62,[65][66][67][68][69] Figure 9. Equivalent circuit model that was used for fitting the Nyquist plot data of the samples with contributions from the grain interiors (gi), grain boundaries (gb) and electrode (e) as shown in Figure 8.…”

Structural stability of anhydrous proton conducting SrZr0.9Er0.1O3−δ perovskite ceramic vs. protonation/deprotonation cycling: Neutron diffraction and Raman studies

“…Round shaped SrZr0.9Er0.1O3-δ, δ ≤ 0.05 [25,39] (called here-after SZE_NH, NH for non hydrated) medium density (90% of theoretical density) perovskite ceramic pellets (diameter of 20mm) were prepared by the AREVA NP group using the method described elsewhere [17][18][19]41,42]. X-ray, Raman, SEM, elemental analysis, density, TGA and dilatometry measurements were used to verify the ceramic quality and crystallographic purity as previously described [25,[42][43][44][45].…”

“…However they are not sufficient to guarantee successful industrial applications because of the lack of data concerning their lifetime. In order to go further than laboratory cells, complex stability/ageing (chemical, mechanical and structural) tests performed on demonstrators in industrial, operating conditions (typically 10 to 20 bar p(H2O)) [17][18][19] are the must. The use of high water pressure by industrialists allows an efficiency increase and in consequence to reduce the cost of Hydrogen production/conversion [20][21][22][23].…”

Impact of Spark Plasma Sintering Conditions on Ionic Conductivity in La1.95Sr0.05Zr2O7-δ Electrolyte Material for Intermediate Temperature SOFCs

“…Incorporation of Protons. Since the discovery of high temperature protonic conductivity in cerates (4,22), many investigations about perovskite-type proton conductors have been performed (23)(24)(25). These proton conductive perovskite-type oxides exhibit protonic conduction under hydrogen containing atmosphere at elevated temperatures.…”