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I–U characteristics at voltages U = 12–150 V in EPD of coatings from a BCSO nanopowder suspension (1) with and (2) without BMA-5 modifi er. (I) Current.
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The method of laser ablation of a target, followed by condensation, was used to obtain a weakly aggregated BCSO nanopowder from barium cerate. The dispersity, fraction composition of the nanopowder, electrokinetic potential of its nonaqueous dispersions, and electrokinetic parameters of the electrophoretic deposition process were determined. An ult...
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Context 1
... suspensions of the BCSO nanopowder were used to form coatings of a solid electrolyte in an SOFC on the LNO cathode by the electrophoretic deposition method. Figure 2 shows current-voltage (I-U) characteristics at voltages in the range 12-150 V for BCSO nanopowder suspensions (10 g L -1 ) in a mixed dispersion medium with addition of BMA-5 (3 g L -1 ) and without it. It can be seen in Fig. 2 that the current linearly depends on voltage, i.e., the resistance is voltage-independent in this range. ...
Context 2
... used to form coatings of a solid electrolyte in an SOFC on the LNO cathode by the electrophoretic deposition method. Figure 2 shows current-voltage (I-U) characteristics at voltages in the range 12-150 V for BCSO nanopowder suspensions (10 g L -1 ) in a mixed dispersion medium with addition of BMA-5 (3 g L -1 ) and without it. It can be seen in Fig. 2 that the current linearly depends on voltage, i.e., the resistance is voltage-independent in this range. No nonlinearity or hysteresis of I-U characteristics was found in a study of the given suspension. The I-U characteristic in an EPD for a suspension in the presence of BMA-5 is characterized by a higher dc resistance as compared ...
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Potentialities of the method of electrophoretic deposition of thin-film coatings based on micrometer powders of multidoped barium cerate BaCe0.8Sm0.19Cu0.01O3–δ (BCSCuO) and BaCe0.89Gd0.1Cu0.01O3–δ (BCGCuO) were considered. Micrometer powders of BCSCuO and BCGCuO were produced by the methods of solid-phase and citrate-nitrate syntheses, respectivel...
Citations
... One of the main aspects of obtaining a high-quality coating in the EPD process is the presence of a stable dispersion of YSZ. The formation of a dense, well-anchored coating is possible only if the EPD proceeds in sedimentationally and aggregatively stable suspensions [18][19][20]. The stability of the suspension is influenced by the choice of the dispersion medium and the ratio of the initial components. ...
Solid oxide fuel cells are promising hydrogen energy devices. The goal of this research was to create ceramic layers for SOFCs based on yttria-stabilized zirconia (YSZ) and to investigate their parameters. YSZ ceramic layers with a thickness of 5.14 μm on a porous NiO–YSZ substrate and 7 μm on pyrolytic graphite were obtained by electrophoretic deposition. X-ray diffraction and electron microscopy were used to determine the composition, structure, and morphological features of ceramic layers. The effects of the substrate's nature, the degree of dispersion of the initial YSZ powder, and the heat treatment conditions on the properties of the ceramic layer YSZ were considered.
... It turned out that the EPD process significantly affects the aggregative stability of the suspensions. In the works [11,26,27] it was shown that suspensions of oxide nanoparticles obtained by laser synthesis are highly stable in isopropyl alcohol as a result of so called "selfstabilization" process. In the initial YLO_i_1 suspension, the size distribution of particles (aggregates of nanoparticles) is shown in Figure 2a. ...
... It turned out that the EPD process significantly affects the aggregative stability of the suspensions. In the works [11,26,27] it was shown that suspensions of oxide nanoparticles obtained by laser synthesis are highly stable in isopropyl alcohol as a result of so called "self-stabilization" process. In the initial YLO_i_1 suspension, the size distribution of particles (aggregates of nanoparticles) is shown in Figure 2a. ...
In the present work, a study was carried out to investigate the key factors that determine the uniformity, mass, thickness, and density of compacts obtained from nanopowders of solid solutions of yttrium and lanthanum oxides ((LaxY1−x)2O3) with the help of the electrophoretic deposition (EPD). Nanopowders were obtained by laser ablation of a mixture of powders of yttrium oxide and lanthanum oxide in air. The implemented mechanisms of the EPD and factors of stability of alcohol suspensions are analyzed. It has been shown that acetylacetone with a concentration of 1 mg/m2 can be used as a dispersant for stabilization of isopropanol suspensions of the nanoparticles during the EPD. It was shown that the maximum density of dry compacts with a thickness of 2.4 mm reaches 37% of theoretical when EPD is performed in vertical direction from a suspension of nanopowders with addition of acetylacetone.
... In addressing the problem with deposition of 8YSZ films from aqueous suspensions, Cherng et al. [138] the Ni-8YSZ anode (Fig. 6). Recently, this additive was successfully adopted to prepare aqueous suspensions based on the 8YSZ, NiO-8YSZ and LSM powders and deposition of the entire micro-tubular cell structure was performed by EPD without the use of noble metal Table 1 Dispersing media and additives used for preparation of stable suspensions based on solid state electrolyte powders [130,131,132,133,134,135,136,137,138,35,36,127,128,139,140,141,142,143,144,145,55,58,146,147,148,149,32,150,33,151,152,153,154]. ...
... This can significantly simplify the technology, reduce the amount of organic additives and decrease the sintering temperature of thin-film layers and, as a result, improve the quality of the resulting films. A series of works by Kalinina et al. [128,145,153,186,187] was devoted to the preparation and investigation of stable suspensions based on the solid electrolyte powders produced by the LEC method and the study of the effect of the degree of de-aggregation of YSZ nanoparticles in suspensions on the process of electrophoretic deposition. Preparation of suspensions based on doped-ceria LEC-powders of different content (single and multidrop) are presented in [145]. ...
... For nonaqueous suspensions of nanosized electrolyte powders (including LECpowders) such binders have been tested as polyvinyl butyral (PVB), copolymer of butyl methacrylate with 5 mol. % of methacrylic acid (BMMA-5), poly-acrylic acid, polyethylenimine, polyvinyl acetate, 4hydroxybenzoic acid, acrylic acid-acrylate copolymer and acrylateacrylamide copolymer [33,55,58,130,153,178,189,190]. Dispersing aids with an inherent binding effect (copolymers) such as poly(dimethyldiallylammonium chloride) (PDDA) or PEI are the most preferable [63,188]. ...
Solid oxide fuel cells (SOFCs) have been attracting considerable attention as prospective power sources with a variety of applications. Much current research is directed towards lowering the SOFC operating temperature in order to reduce the costs related to insulation, materials, start-up and degradation. Development of versatile technologies is required to fabricate a SOFC with a thin-film electrolyte membrane to decrease ohmic losses at reduced temperatures and to form graded electrodes that have superior electrochemical performance. Electro-phoretic deposition (EPD) is one of the most technologically flexible and cost-effective methods currently available for the thin film formation. This review briefly highlights the fundamental regularities and mechanisms of EPD and shows the evolution of the mathematical model of EPD considering classical and recent studies in this area. It presents current approaches to overcoming the challenges in the realization of the EPD process such as the choice of dispersion medium and additives, preparation of stable suspensions, bubble-free deposition from aqueous suspensions, formation of substrates with optimized porosity and conductivity and deposition on non-conducting substrates. It also summarizes the latest advances in deposition of different SOFCs' functional layers (dense, porous and multilayered) and entire cell structures, including micro-tubular cells.
... The LEC method is advantageous in obtaining nano-sized powders for which a decreased sintering temperature is needed to obtain gas-tight coatings. However, in the case of Ba-containing electrolyte, in the LEC process it is difficult to produce powders of nominal compositions, as demonstrated by the specific example of BaCe 0.8 Sm 0.2 O 3-δ (BCSO) in [115]. Nevertheless, in the study it was revealed that successive annealing of the BCSO LEC powder at the temperatures of 800-1400°C allowed the content of unidentified crystalline phases to be reduced to a trace amount (<5 wt%). ...
Thin film technologies have attracted ever-growing interest in different industrial areas. Concerning solid oxide fuel cells (SOFCs), especially devices operating in the intermediate temperature range, such technologies are applied particularly for the deposition of dense, gas-tight electrolyte films with a thickness of several µm to decrease ohmic resistance and enhance the cell performance. The main requirements for the technology selected are its low cost, simplicity of the equipment used, short depo-sition time and flexibility regarding the cell shape. First, we overview thin-film technologies adapted to the deposition of SOFC functional layers, discussing their strengths and weaknesses, with special attention given to electrophoretic deposition (EPD) as being the most simple and cost-effective col-loidal method to fabricate different electrolyte films. Then we present the contribution of our scientific group in the development of the EPD method. The preparation of stable suspensions for the EDP is one of the key requirements for its successful implementation and reproducibility; this was considered in detail and the effect of self-stabilization in suspensions based on nanopowders (7-15 nm), obtained by the method of laser evaporation with consequent condensation, was discussed. Such suspensions, exhibiting high positive ζ-potential values (30-50 mV), were shown to be suitable for EPD without the addition of dispersants or iodine. The requirements for the electrode substrates were formulated and a model of particle aggregation near the porous substrate surface was proposed. Deposition parameters were established for different electrolyte films-commonly used yttria-stabilized zirconia, single and multiply doped CeO 2 and proton-conducting doped BaCeO 3 electrolytes. As was shown, the deposition on the highly conducting cathode substrates is simpler to implement than the EPD on non-conducting anode substrates and, in addition, it produces high quality films which render high OCV values and superior SOFC performance.
... Because the laser evaporation-condensation method gives unstable results in the preparation of the barium-cerate-based electrolytes and requires further improvements [29], in this work BaCe 0.89 Gd 0.1 Cu 0.01 O 3 -δ (BCGCuO) was synthesized using the pyrolysis method [30]. The synthesis was carried out by using BaCO 3 (analytical grade), Сe(NO 3 ) 3 · 6H 2 O (reagent grade), Gd(NO 3 ) 3 · 6H 2 O (reagent grade), and CuO (reagent grade) as raw materials, with the adding of nitric acid (pH 2) during heating. ...
Potentialities of the method of bilayer thin-film electrolyte electrophoretic deposition onto cathodic substrate are analyzed. Ce0.8Sm0.2O1.9–δ (SDC) nanopowder and BaCe0.89Gd0.1Cu0.01O3–δ BCGCuO) micropowder are prepared by the methods of laser evaporation–condensation and pyrolysis, respectively. The effect of ultrasonic treatment on the SDC and BCGCuO particle distribution in suspensions and their electrokinetic properties are studied. The using of the ultrasonic treatment combined with centrifugation allowed obtaining an aggregative-stable suspension of the BaCe0.89Gd0.1Cu0.01O3–δ micron particles in the isopropanol–acetylacetone mixed medium (70/30 v/v) that is characterized by high zeta potential. Ce0.8Sm0.2O1.9–δ and BaCe0.89Gd0.1Cu0.01O3–δ thin films are obtained at the La2NiO4 +δ cathode substrate using electrophoretic deposition; microstructure and electric properties of the prepared thin-film structures are studied. The conductivity and electric properties of the bilayer electrolyte were found to be determined by the Ce0.8Sm0.2O1.9–δ film properties. Despite the sintering high temperature, the grain structure of the BaCe0.89Gd0.1Cu0.01O3–δ film is underdeveloped; this is determined by the micron powder properties.
The key features and challenges of the use of electrophoretic deposition for the formation of functional layers of solid oxide
fuel cells are considered. Theoretical models and experimental results of the studies of electrophoretic deposition are
presented. The analysis covers the physicochemical deposition mechanisms, methods for preparing suspensions and
conditions necessary for obtaining thin-film electrode and protective single- and multi-layers with both dense and porous
structure for solid oxide fuel cells. The prospects of theoretical simulations of the method and its potential practical
applications are evaluated.
