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Proton conducting Y‐doped BaZrO3, BaCeO3 and their solid solutions are receiving increasing attention due to their promising application as electrolytes in ceramic fuel cells and electrolysis cells. However, the literature indicates a clear tendency that the performance of the cells increases with increasing Ce content in the electrolyte. In this work, to elucidate this phenomenon, a systematic work is performed on investigating the phase, hydration, and transport behaviors of BaZr0.8−xCexY0.2O3−δ (BZCY20). The results reveal that in the temperature range between 500 and 700 °C, with increasing Ce content, the dehydration temperature elevates and the proton concentration increases, showing that the Ce component favors the stabilization of protons. Furthermore, the transport number of hole conduction decreases, whereas the transport number of ionic conduction increases with the increasing Ce content. By further separating the contribution of oxide ions and protons, it is found that the oxide ion conductivity increases with the increasing Ce content at higher temperatures of 600 and 700 °C. Such decreased hole conductivity and increased oxide ion conductivity result in the enhancement of the ionic conduction of BZCY20 with increasing Ce content, and therefore improve the performance of fuel cells and electrolysis cells. [ABSTRACT FROM AUTHOR]

SrCe 0.9 Y 0.1 O 3-δ -Ce 0.9 Y 0.1 O 2-δ (SCY-YDC, 1:1 mole ratio), as a novel composite electrolyte, was successfully synthesized and characterized. X-ray diffraction patterns showed that SCY-YDC composite electrolyte is a mixture of SCY and YDC. Besides, no impurity phase emerged after sintering at 1550 °C for 10 h. AC impedance spectroscopy was used to determine the electrical properties of SCY-YDC at 500–800 °C in various atmospheres. Partial conductivities of oxygen vacancies, protons, and electrons (p-type) were calculated using the defect structure model. Results showed that SCY-YDC is a mixed (hole, proton, and oxygen-ion) conductor. Moreover, the contribution of holes is minor at 650–800 °C in high pressure (1 atm) or low pressure (10−4 atm) O 2 atmospheres. Dominant carrier switched from protons to oxygen ions as temperature increased at vapor pressure in air of 0.038 atm. Total conductivity for SCY-YDC is 6.19 × 10−3 S cm−1 at 800 °C under pO 2 = 1 atm and pH 2 O = 6 × 10−3 atm, which is higher than that of SCY (2.47 × 10−3 S cm−1). Results also showed that SCY-YDC composite material exhibits higher ionic conductivity and lower electron-hole conductivity than SCY. Electron-hole transference number for SCY-YDC is 0.049 at 800 °C in pO 2 = 0.21 atm and pH 2 O = 0.038 atm. Ultraviolet–visible spectrophotometry results provided evidence that SCY-YDC can suppress electron conduction. [ABSTRACT FROM AUTHOR]

An electrolyte in fuel cells requires not only high ionic conductivity, but also high transport numbers of ionic conduction. Although Y‐doped BaZrO3 is regarded to be the most promising candidate as the electrolyte in protonic ceramic fuel cells (PCFCs), significant hole conduction generates in wet oxygen at high temperatures. With the aim to increase the transport number of ionic conduction, in this work, Sr and Ca were introduced to partially substitute Ba in BaZr0.8Y0.2O3‐δ. The results revealed that a single cubic perovskite phase was obtained for Ba0.95Ca0.05Zr0.8Y0.2O3‐δ and Ba1‐xSrxZr0.8Y0.2O3‐δ (x = 0.05, 0.10, 0.15, 0.20 or 0.40). However, replacing Ba with Sr resulted in almost no increase in the transport number of ionic conduction in wet oxygen atmosphere, but drastic decrease in proton conductivity at all replacement levels. In addition, Ba0.95Ca0.05Zr0.8Y0.2O3‐δ shows no meaningful change in the transport number of ionic conduction, compared with BaZr0.8Y0.2O3‐δ. Incorporating Ca or Sr into the Ba‐site of BaZr0.8Y0.2O3‐δ appears to impart no positive influence on electrochemical properties. These interesting results also indicate that the hole conductivity decreases with the decrease in proton conductivity, and will aid to consider the hole conduction mechanism. BaHfO3 doped with 10 and 20 mol% Y was also prepared. A bimodal microstructure was observed for BaHf0.9Y0.1O3‐δ, whereas BaHf0.8Y0.2O3‐δ shows uniform grain size after sintering at 1600°C for 24 hours. The transport numbers of ionic conduction and bulk conductivity in such Y‐doped BaHfO3 samples are close to those of BaZrO3 doped with the same amount of Y. [ABSTRACT FROM AUTHOR]

An electrolyte in fuel cells requires not only high ionic conductivity, but also high transport numbers of ionic conduction. Although Y‐doped BaZrO3 is regarded to be the most promising candidate as the electrolyte in protonic ceramic fuel cells (PCFCs), significant hole conduction generates in wet oxygen at high temperatures. With the aim to increase the transport number of ionic conduction, in this work, Sr and Ca were introduced to partially substitute Ba in BaZr0.8Y0.2O3‐δ. The results revealed that a single cubic perovskite phase was obtained for Ba0.95Ca0.05Zr0.8Y0.2O3‐δ and Ba1‐xSrxZr0.8Y0.2O3‐δ (x = 0.05, 0.10, 0.15, 0.20 or 0.40). However, replacing Ba with Sr resulted in almost no increase in the transport number of ionic conduction in wet oxygen atmosphere, but drastic decrease in proton conductivity at all replacement levels. In addition, Ba0.95Ca0.05Zr0.8Y0.2O3‐δ shows no meaningful change in the transport number of ionic conduction, compared with BaZr0.8Y0.2O3‐δ. Incorporating Ca or Sr into the Ba‐site of BaZr0.8Y0.2O3‐δ appears to impart no positive influence on electrochemical properties. These interesting results also indicate that the hole conductivity decreases with the decrease in proton conductivity, and will aid to consider the hole conduction mechanism. BaHfO3 doped with 10 and 20 mol% Y was also prepared. A bimodal microstructure was observed for BaHf0.9Y0.1O3‐δ, whereas BaHf0.8Y0.2O3‐δ shows uniform grain size after sintering at 1600°C for 24 hours. The transport numbers of ionic conduction and bulk conductivity in such Y‐doped BaHfO3 samples are close to those of BaZrO3 doped with the same amount of Y. [ABSTRACT FROM AUTHOR]

Fast ion-conducting (FIC) system composed of xCdI2-(100-x)[44.4Ag2SO4-55.6(40TeO2-60B2O3)] has been prepared by melt-quenching method. The prepared samples were characterized by X-ray diffraction (XRD), impedance, and transport studies. XRD, DSC studies conclude that the samples with x = 0 to 20 show predominantly glassy nature. Conductivity measurements were performed in the frequency range 20 Hz-3 MHz by varying temperature from 30 to 150 °C. Electrical parameters such as conductivity and activation energies of all the samples were evaluated by complex impedance analysis and Arrhenius plots, respectively. The obtained results of conductivity are discussed using exchange reaction between the cations based on Lewis’ hard and soft acids and bases (HSAB) principle. Ionic conductivity is identified as being mainly due to Ag+ ions. The highest conductivity (order of 10−4 S cm−1) and ionic current (2.063 μA) is observed for CBT20 sample at room temperature; hence, it can be used as the best electrolyte material for solid-state battery application. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple analytical method was developed to determine D , t + , and Λ. • A proposed model reproduced the time course of the measured current. • D and t + determined by this method showed the same trend as the reported values. • Λ calculated using D and t + showed the same trend as the measured impedance values. • It is important to exclude non-Faradaic processes for accurate analysis. A simple method for simultaneously determining the effective diffusion coefficient of salt (D), transport number (t +), and molar conductivity (Λ) of binary liquid electrolytes using chronoamperometry in a symmetrical parallel-plate lithium cell is proposed. The curve was fitted assuming a mass-transport-limited process to avoid the effect of the nonfaradaic current in chronoamperometry. The fitting function was based on the diffusion model. The D , t + , and Λ values obtained over a wide concentration range (0.005–1.0 M lithium perchlorate in propylene carbonate) show the same trend as those reported in the literature. Furthermore, the molar conductivity of the electrolyte determined using the proposed method also shows the same trend as that measured using the AC impedance method. [ABSTRACT FROM AUTHOR]

Electrodialysis (ED) of solutions containing ternary combination of electrolytes (NaCl, KCl, CaCl 2 , MgCl 2 , FeCl 3 ) was carried out. Besides linear velocity of the fluid flowing through the ED cell, physical properties of cations and their interaction with the gel phase of membrane significantly influenced ion transport. The role of concentration polarization was evaluated from limiting current density (LCD) measurement. Theoretically estimated LCD values based on effective diffusivity of each ions and mass transfer coefficients (Sherwood number, Sh correlation) satisfactorily (error ± 5–7%) predicted experimental data. Measurement of transport number, adsorption equilibrium, water uptake and membrane resistance were carried out for each composition to understand the role of cations — membrane equilibrium in ion transport. Cations with higher charges showed reduced transport number, higher adsorption and higher resistance over cation exchange membrane (CEM). Water uptake measurement of equilibrated CEM showed negligible difference when cations of similar charges were interchanged while a meager 1.5% variation was noted when cations of different charges were interchanged. [ABSTRACT FROM AUTHOR]

Molecular Dynamics simulations of the BAB type triblock copolymer lithium poly[(4-styrenesulfonyl) (trifluoromethylenesulfonyl) imide)]-block-poly(ethylene oxide)-block-lithium poly[(4-stryrenesylfonyl) (trifluoromethanesulfonyl) imide] (P(STFSILi)-b-PEO-b-P(STFSILi)) were carried out for different simulation temperatures and B-block lengths. By covalently binding the anion to the polymer backbone, it is immobilised and the cation transference number thereby raised significantly. It was found that the Li-ion diffusion decreases exponentially with growth of the B-block length. The poly(ethylene oxide) matrix dissolves Li-ions already during the equilibration stage of the simulation, and no Li-ion diffusion pathways were identified along the STFSI branches, which significantly influence the transport properties of the material. [ABSTRACT FROM AUTHOR]

Abstract: Single-ion activity coefficients reported in literature for 10 ternary common-ion liquid-junction systems with KCl(aq) in the reference solutions and MX(aq) electrolytes in the test solutions at 25°C are reproduced in the present work numerically over wide MX molality ranges by functions of mean activity coefficients and transport numbers of ions in the liquid junction, the MX being BaCl2, CaCl2, CsCl, HCl, KF, K2SO4, LiCl, MgCl2, NaCl and SrCl2. The activity coefficients of solutes in the ternary systems are represented in the calculations by Scatchard's Neutral Electrolyte Model, and the transport numbers by a molality-based version of Van Rysselberghe's rule. An analysis is given of factors affecting the magnitudes of the functions, among them composition profiles in the liquid junction, formulation of Van Rysselberghe's rule, concentration dependence of ion mobilities, and non-ideality of electrolyte mixing. Most importantly, it is found that the exact functions can be approximated reasonably closely by a product of the mean activity coefficients in binary MX and KCl solutions, both at molality of the test solution, raised to powers that can be understood as related to effective transport numbers of the respective non-common ions in the liquid junction. Advantage is taken of the simple formulas to interpret the observed concentration dependences of single-ion activity coefficients in terms of the mean activity coefficients and effective transport numbers. [Copyright &y& Elsevier]

Abstract: Membrane potential and membrane conductance measurements have been carried out using Dowex-50Kynar membrane, sodium chloride and urea as a hydrotrope, mixture of varying composition to examine the hydrotrope effect on electrochemical character of the membrane. A significant change on membrane electrochemical character is observed in the presence of hydrotrope due to changed co-ion exclusion. The Donnan equilibrium has been incorporated to estimate the activity coefficient of counter ion, yp m, and solute, y± m in the membrane phase along with the parameter, so called Ф expressing non-ideality. Solute rejection performance of the membrane is examined when electrolyte concentration remains constant and hydrotrope concentration varies and vice-versa. In both cases, membrane specific conductance depends on NaCl and hydrotrope concentrations differently. Friction caused through the membrane by the variation in concentration of hydrotrope is greater than friction caused by the variation in concentration of NaCl. Zeta potential is sensitive to the variation of hydrotrope concentration but insensitive to the variation of electrolyte concentration. The membrane system shows the behavior of NF membrane because Pe≪1 is estimated in both cases. [Copyright &y& Elsevier]

Abstract: The hybrid direct carbon fuel cell is a direct carbon fuel cell concept that combines a solid oxide fuel cell with a molten carbonate fuel cell electrode. This offers efficient conversion of coal or biomass derived carbons to electricity. In this study we aim to improve the electrical performance of this cell by using gadolinia doped ceria (GDC) as either a protection layer over a YSZ electrolyte or as the electrolyte itself. In our study, the electrical performance of several tubular cell geometries were investigated using impedance spectroscopy both with and without gas flows of carbon dioxide or nitrogen. Integrity of microstructure including possible layer delamination effects were investigated by SEM. Promising values of power and resistance were observed using a GDC material as electrolyte at intermediate temperature reducing the operation temperature compared to YSZ, doubling the power of each cell. [Copyright &y& Elsevier]

The transport number ratio between anion and chloride ion Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. was measured to discuss the anion permselectivity in an electrodialysis (ED). It was shown that Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. changed with the progress of ED. In this paper, a mechanism of anion permselectivity in ED was theoretically discussed with an equivalent circuit to find the reason why Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. changed with the progress of ED. It was found that Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. depended on the total electrolyte concentration of the diluted compartment CB. Then, Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. changes with the progress of ED, since CB decreases with the progress of ED. In addition, the simulation of ED with the equivalent circuit was successfully performed using the electric resistances of the equivalent circuit obtained from the analysis of Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed.. [ABSTRACT FROM AUTHOR]

Abstract: The growth of barrier anodic film is considered theoretically with regard to the migration of three ionic carriers: oxygen and metal ions and electrolyte anions. It is shown that the consideration of anion transport leads to the conclusion that the film grows at three interfaces: the metal/oxide and oxide/electrolyte interfaces and the interface between an oxide layer containing electrolyte anions (contaminated layer) and the oxide layer free of them (“pure” layer). The error in the measured transport numbers of metal and oxygen, which is caused by ignoring a contribution of electrolyte anions to the total charge transport, is maximum in the absence of anion motion. [Copyright &y& Elsevier]

Abstract: This study examines the effects of biofouling on the electrochemical properties of cation exchange membranes (CEMs), such as membrane electrical resistance (MER), specific proton conductivity (SC), and ion transport number (t+ ), in addition to on microbial fuel cell (MFC) performance. CEM biofouling using a 15.5±4.6μm biofilm was found to slightly increase the MER from 15.65Ωcm2 (fresh Nafion) to 19.1Ωcm2, whereas an increase of almost two times was achieved when the electrolyte was changed from deionized water to an anolyte containing a high cation concentration supporting bacterial growth. The simple physical cleaning of CEMs had little effect on the Coulombic efficiency (CE), whereas replacing a biofouled CEM with new one resulted in considerable increase of up to 59.3%, compared to 45.1% for a biofouled membrane. These results clearly suggest the internal resistance increase of MFC was mainly caused by the sulfonate functional groups of CEM being occupied with cations contained in the anolyte, rather than biofouling itself. [ABSTRACT FROM AUTHOR]

Solid polymer electrolyte system, Polyethylene Oxide (PEO) complexed with potassium bicarbonate (KHCO3) salt has been prepared by solution-cast technique. Several experimental techniques such as IR, Differential Scanning Calorimetry (DSC), composition dependence conductivity, temperature dependence conductivity in the temperature range of 308-368 K and transport number measurements have been employed to characterize this polymer electrolyte system. The conductivity of the (PEO+KHCO3) electrolyte is about 103 times larger than that of pure PEO at room temperature. The transference data has shown that the charge transport in these polymer electrolyte systems is predominantly due to ions. [ABSTRACT FROM AUTHOR]

Abstract: In order to discuss the hetero-phase effect of the coexisting solid phase on the ionic conduction in non-aqueous lithium electrolyte solution, the conductivity and transport number of ionic species in non-aqueous lithium perchlorate solution/montmorillonite clay composite system were measured using Hittorf''s cell. Transport number of lithium ion rapidly increased as the clay content increased, while total conductivity gradually decreased. The calculated ionic mobility of lithium ion was constant in the liquid content range of 75–90vol.%. The activation energy of the conductivity for both ions separately obtained from the temperature dependence of the ionic mobilities. The activation energy of lithium ion was ca. 10kJmol−1 and extremely lower than anion species. It is proved that the lithium ion transfer is promoted by the cation exchange materials using inorganic clay materials. It is suggested that the lithium ions can transfer through the inside of clay structure and anion transfer is hindered by the repulsion between anion species and clay skeleton structure. [Copyright &y& Elsevier]