X-ray Micro-Computed Tomography: A Powerful Device to Analyze the 3D Microstructure of Anode-Electrolyte in BaZr0.8Y0.2O3 Protonic Ceramic Electrochemical Cells and the Reduction Behavior

New advanced fuel cell technologies are moving towards high-temperature proton conductors (HTPCs) to meet environmental issues. Their elaboration remains a challenge and micro-computed tomography (µCT) is an innovative way to control their quality. NiO-BZY anodic supports of a protonic ceramic electrochemical cell (PCEC), elaborated by co-tape casting and co-sintered at 1350 °C, were coated with a BZY20 electrolyte layer by DC magnetron sputtering. The µCT allowed to observe defects inside the volume of these PCEC half-cells and to show their evolution after an annealing treatment at 1000 °C and reduction under hydrogen. This technique consists in obtaining a 3D reconstruction of all the cross-sectional images of the whole sample, slice by slice. This allows seeing inside the sample at any desired depth. The resolution of 0.35 µm is perfectly adapted to this type of problem considering the thickness of the different layers of the sample and the size of the defects. Defects were detected, and their interpretation was possible thanks to the 3D view, such as the phenomenon of NiO grain enlargement explaining defects in the electrolyte, the effect of NiO reduction, and finally, some anomalies due to the shaping process. Ways to anticipate these defects were then proposed.

Colloidal Processing of Y0.08Zr0.92O2/La0.80Sr0.20MnO3 Semi-Cells Using a Sr-Doped Lanthanum Manganite Synthesized by a Citrate Route

In this paper, the interface between yttria stabilized zirconia (Y0.08Zr0.92O2, YSZ) electrolyte and Sr-doped lanthanum manganite (La0.80Sr0.20MnO3, LSM) cathode for solid oxide fuel cells (SOFCs) is studied. For such a purpose, the combination of a suitable synthesis route for obtaining fine powders and simple aqueous colloidal shaping routes is proposed. The synthesis of nanosized particles of La0.80Sr0.20MnO3 by a citrate route and their full characterization, including the colloidal stability and the densification and phase development determined by X-ray diffraction and electron microscopy at different temperatures, is reported. In a second step, YSZ tapes were obtained by aqueous tape casting and used as substrates for the preparation of LSM coatings by dip-coating using aqueous slurries. YSZ tapes were used either in the green state or after a pre-sintering treatment. Co-sintering at 1350 °C led to a sharp interface with excellent adhesion, also achieved when coating pre-sintered tapes. In both cases, the substrates are dense and the coatings are porous, with thicknesses of 85 and 60 μm for green and pre-sintered tapes, respectively. No diffusion of Zr and Y occurs at the LSM layer, but some diffusion of La and Mn towards the YSZ layer takes place.

Preparación y caracterización de películas fotoluminiscentes de PVA dopadas con complejos metal-orgánicos de Eu3+

El presente trabajo se centra en la caracterización de una matriz polimérica de alcohol polivinílico (PVA), preparada a partir de la dispersión de un complejo mononuclear organometálico a base de europio trivalente, Eu3+. Los complejos de Eu3+ se sintetizaron previamente en medio acuoso a condiciones ambientales empleando aniones benzoato como ligandos orgánicos, que sigue a la formula Eu(OOCC6H5)3· (H2O)3 (Para fines prácticos la identificaremos como EuL3. Una vez caracterizado el complejo obtenido en forma de polvo, se dispersó mediante ultrasonido en la matriz de PVA. Se prepararon y caracterizaron películas con diferentes proporciones molares del complejo en relación con el polímero huésped. Las películas de 0.5 mm de espesor fueron obtenidas mediante la técnica “Tape-casting“. Las caracterizaciones que se realizaron mediante la técnica FT-IR y espectroscopia de fluorescencia. La matriz de PVA genera una sensibilización en la excitación del complejo EuL3 presentando un desplazamiento en el espectro de excitación de 288 a 280 nm; además, se observó un aumento en la emisión luminiscente debido a procesos de transferencia de energía intra o intermolecular de la matriz hacia los núcleos activos de europio.

Metal-supported SOFC Fabricated by Tape Casting and Its Characterization: A Study of the Co-sintering Process

Metal-supported SOFC consists of metallic and ceramic multilayers. Since the cell has to be flat, interaction between the layers that results in a flat sintered layer needs to be studied. The method used here was changing the starting materials through several experiments. Here, we highlight the effects of pore former in metal slurry on the sintered half-cell multilayer of a 430L metallic support, an NiO-8YSZ anode, and an 8YSZ electrolyte. The results show that by changing the amount of pore former in the 430L metal slurry changed the sinterability of the metal layer. This change of the sinterability of the metal support affected the final warpage state of the cell. This study aid in explaining the sintering phenomena between layers of metal-supported SOFCs.

Nano-Fibrous Networks from Co-Assembly of Amphiphilic Peptide and Polyelectrolyte

Organize the matter on an increasingly small scale is sought in order to increase the performance of materials. In the case of porous materials, such as filtration membranes, a compromise must be found between the selectivity provided by this nanostructuring and a permeability in particular linked to the existing pore volume. In this work, we propose an innovative waterborne approach consisting in co-assembling peptide amphiphiles (PA) which will provide nanostructuring and polyelectrolytes which will provide them with sufficient mechanical properties to sustain water pressure. C16-V3A3K3G-NH2 PA nanocylinders were synthesized and co-assembled with poly(sodium 4-styrenesulfonate) (PSSNa) into porous nano-fibrous network via electrostatic interactions. The ratio between C16-V3A3K3G-NH2 and PSSNa was studied to optimize the material structure. Since spontaneous gelation between the two precursors does not allow the material to be shaped, various production methods have been studied, in particular via tape casting and spray-coating. Whereas self-supported membranes were mechanically weak, co-assemblies supported onto commercial ultrafiltration membranes could sustain water pressure up to 3 bars while a moderate permeability was measured confirming the existence of a percolated network. The produced membrane material falls into the ultrafiltration range with a pore radius of about 7.6 nm.

Preparation of carbon anode sheet precursor using raw Air Laya–Bukit Asam coal and its application for battery

Research has been carried out on manufacturing carbon electrode thin sheets used as anode for solid battery cells. The material used is raw coal carbonized at 800 and 1000oC, polyvinylidene fluoride (PVDF), and N-Dimethylacetamide (DMAC) as a solvent. Observation of crystal structure by X-rays diffraction method shows a diffraction pattern where crystallites in all product samples have an intermediate structure between graphite and amorphous known as a turbostratic structure or a random layer lattice structure. The distance between the crystallite structure’s aromatic layers (d002) is in the range 3.52-3.62 Å. Aromaticity (fa) is in the range 0.42 - 0.48 for all samples. The high value of d002 indicated that the crystallinity or level of graphitization obtained by all samples was still low. Manufacturing technique using a Doctor Blade-based tape casting method. The discharge capacities of the samples reach about 60 and 18 mAh.g-1, while their charge capacities at the first cycle are 50 and 16 mAh.g1, respectively. Cyclic voltammetry (CV) was performed using anodes resulted at 0.1 to 2.3 volt. During the forward scan, CV curves of the sample reveal a reduction current starting from around 1.2 V and exhibiting two-reduction waves, between 1.2 and 0.6 V.

High-Performance BaTiO3 Film Based on Aqueous Tape Casting for Ultrathin MLCC Applications

Environment-friendly aqueous tape-casting are proposed as an inevitable tendency for producing a high-quality BaTiO3-based film in the development of ultra-thin multilayer ceramic capacitors. In this study, aqueous BaTiO3 suspension with high solids loading produced by using polycarboxylate ammonium salt APC (dispersant), proprietary acrylic formulation binder solution WB4101 (binder), and acrylic resin PL002 (plasticizer), respectively. It is demonstrated that the green density, tensile strength, and strain at failure of the 9.5-μm-thin BaTiO3 tape achieves 3.65 g/cm3, 7.65 MPa, and 11%, respectively. In particular, the capacitance and dielectric loss of BaTiO3-based MLCC chips at room temperature are found to be approximately 28 nF and 0.02 compatible with Pt electrodes. Additionally, the TCC, ferroelectric hysteresis loops, change of dielectric constants versus DC-BIAS field, and evolution of electrical resistivity under accelerated DC stressing of BaTiO3-based MLCC are studied. The results provide an effective method for the future improvement in aqueous MLCC applications.