La$_{0.58}$Ca$_{0.4}$Co$_{0.2}$Fe$_{0.8}$O$_{3-δ}$ (L58CCF) was synthesized and evaluated as a cathode electrode for intermediate temperature solid oxide fuel cells (IT-SOFC) based on the Y$_2$O$_3$-stabilized ZrO$_2$ (YSZ) electrolyte. The effect of sintering temperature on the L58CCF performance was investigated. The best Area specific resistances (ASRs) for the L58CCF sintered at 950 $^{\circ}$C were 1.218, 0.447, 0.228, 0.156, 0.099 $Ω.cm^{2}$ at 600, 650, 700, 750, 800 $^{\circ}$C, respectively.
We evaluated for the first time the use of nanostructured layered perovskites of formulae LnBaCo2O6-d with Ln = Sm and Gd (SBCO and GBCO, respetively) as SOFC cathodes, finding promising electrochemical properties in the intermediate temperature range (~700°C). The synthesis of these nanomaterials, not reported before, was achieved by using porous templates to confine the chemical reagents in regions of about 200 nm and 800 nm. The performance of nanostructured SBCO and GBCO cathodes for the oxygen reduction reaction was analyzed in symmetrical cells using Gd2O3-doped CeO2 (GDC) as electrolyte…
Mechanical properties of porous SOFC electrodes are largely determined by their microstructures. Measurements of the elastic properties and microstructural parameters can be achieved by modelling of the digitally reconstructed 3D volumes based on the real electrode microstructures. However, the reliability of such measurements is greatly dependent on the processing of raw images acquired for reconstruction. In this work, the actual microstructures of La0.6Sr0.4Co0.2Fe0.8O3-d (LSCF) cathodes sintered at an elevated temperature were reconstructed based on dual-beam FIB/SEM tomography. Key micros…
Critical to the development of improved solid oxide fuel cell (SOFC) technology are novel compounds with high oxygen reduction reaction (ORR) catalytic activity and robust stability under cathode operating conditions. Approximately 2145 distinct perovskite compositions are screened for potential use as high activity, stable SOFC cathodes, and it is verified that the screening methodology qualitatively reproduces the experimental activity, stability, and conduction properties of well-studied cathode materials. The calculated oxygen p-band center is used as a first principle-based descriptor of …
Crystal structure, cobalt and iron speciation and oxygen non-stoichiometry of La0.6Sr0.4Co1-yFeyO3-d nanorods for IT-SOFC cathodes
Pontificia Universidad Javeriana（波哥大耶稣会天主教大学）；Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica（康塞普西翁原子中心，国家原子能委员会）；Instituto de Nanociencia y Nanotecnología (INN), CNEA-CONICET（纳米科学与技术研究所，国家原子能委员会-国家科学研究和技术研究委员会）；CONICET / Laboratorio de Cristalografía Aplicada, Escuela de Ciencia y Tecnología, Universidad Nacional de Gral. San Martín（国家科学研究和技术研究委员会/应用晶体学实验室，科学与科技学院，圣马丁国立大学）；CNPEM, Laboratório Nacional de Luz Síncrotron（巴西纳米技术国家研究中心，同步光国家实验室）；Instituto de Física, Universidade de São Paulo（物理研究所，圣保罗大学）
Natural abundance of sodium and its similar behavior to lithium triggered recent extensive studies of cost-effective sodium-ion batteries (SIBs) for large-scale energy storage systems. A challenge is to develop electrode materials with a high electrode potential, specific capacity and a good rate capability. In this work we propose mixed eldfellite compounds \ce{Na_x(Fe_{1/2}M_{1/2})(SO4)2} (M = Mn, Co, Ni) as a new family of high electrode potential cathodes of SIBs and present their material properties predicted by first-principles calculations. The structural optimizations show that these m…
Room Temperature RF Sputtering of Mixed Ionic and Electronic Conductor Nd2Ni0.8Cu0.2O4+d films
Università degli Studi di Salerno（萨莱诺大学）；CNR-SPIN（意大利国家研究委员会自旋物理中心）；University of Salento（萨尔勒托大学）；INFN-Lecce Section（意大利国家核物理研究所莱切分部）；Institut Ruđer Bošković（鲁德耶尔博什科维奇研究所）
La$_2$NiO$_4$ is a very promising cathode material for intermediate and low temperature solid oxide cell applications, due to its good electronic and ionic conductivity, together with its high oxygen exchange activity with a low activation energy. Oxygen incorporation and transport in La$_2$NiO$_4$ (L2NO4) thin films is limited by surface reactions. Hence, tailoring the morphology is expected to lead to an overall improvement of the electrode performance. We report on the growth of nano-architectured La$_2$NiO$_4$ thin film electrodes by Pulsed Injection Metal Organic Vapour Deposition (PI-MOC…
Smoothed Boundary Method Framework for Electrochemical Simulation of Li-ion Battery Cathode with Complex Microstructure: Model, Formulation and Parameterization
Novel highly active, optically-transparent electrode catalyst containing Pt, PtOx, graphene oxide and stacked graphene platelet nanofibers is developed for a cathode of Cu(II/I)-mediated dye-sensitized solar cells.
Composite cathode coatings made of a high energy density layered oxide (Li1.2Ni0.15Mn0.55Co0.1O2, theoretical capacity ~377 mAh/g), polyvinylidene fluoride (PVdF) binder, and electron-conduction additives, were bonded to an elastic substrate. An electrochemical cell, built by pairing the cathode with a capacity-matched graphite anode, was electrochemically cycled and the real-time average stress evolution in the cathode coating was measured using a substrate-curvature technique. Features in the stress evolution profile showed correlations with phase changes in the oxide, thus yielding data com…
La0.6Sr0.4Fe0.8Mn0.2O3 (LSFM) compound is synthesized by Sol-gel method and evaluated as a cathode material for the intermediate temperature solid oxide fuel cell (IT-SOFC). X-ray diffraction (XRD) indicates that the LSFM has a Rhombohedral structure with R-3c space group symmetry. The XRD patterns reveal very small amount of impurity phase in the LSFM and Y2O3-Stabilized ZrO2 (YSZ) mixture powders sintered at 600, 700 and 800 C for a week. The maximum electrical conductivity of LSFM is about 35.35 S.cm-1 at 783 C in the air. The oxygen chemical diffusion coefficients, DChem, are increased fro…
The argyrodite sulfides are getting more and more attractive as highly promising solid-state electrolytes (SSEs) for high-performance all-solid-state batteries (ASSBs), owing to their high ionic conductivity, adequate plasticity, and decent mechanical strength. However, their poor incompatibility with Li metal anode and high voltage cathodes and as well as serious sensitivity to air significantly hinder their practical applications. Herein, we have devised an effective strategy to overcome these challenging shortcomings through modification of chalcogen chemistry under the guidance of theoreti…
Li-O$_2$ batteries (LOB) performance degradation ultimately occurs through the accumulation of discharge products and irreversible clogging of the porous electrode during the cycling. Electrode binder degradation in the presence of reduced oxygen species can result in additional coating of the conductive surface, exacerbating capacity fading. Herein, we establish a facile method to fabricate free-standing, binder-free electrodes for LOBs in which multi-wall carbon nanotubes (MWCNT) form cross-linked networks exhibiting high porosity, conductivity, and flexibility. These electrodes demonstrate …
A novel non-destructive methodology for operando observation of ion intercalation and the state of charge on battery electrodes is presented based on spectroscopic ellipsometry (SE). The potentiality of this technique for performing time-resolved measurements of (de-)lithiation processes on electrode materials has been demonstrated using thin film spinel LiMn$_2$O$_4$ as a cathode for Li-ion batteries. The chemical diffusivity of Li+ ions in this material has been determined by the time evolution of the Li insertion into the film, and in the light of these results, it has been possible to rela…
Hydrogen peroxide (H2O2) formation rates in a proton exchange membrane (PEM) fuel cell anode and cathode were estimated as a function of humidity and temperature by studying the oxygen reduction reaction (ORR) on a rotating ring disc electrode (RRDE). Fuel cell conditions were replicated by depositing a film of Pt/Vulcan XC-72 catalyst onto the disk and by varying the temperature, dissolved O2 concentration and the acidity levels in hydrochloric acid (HClO4). The HClO4 acidity was correlated to ionomer water activity and hence fuel cell humidity. The H2O2 formation rates showed a linear depend…
We present theoretical analysis on why and how rechargeable metal-air type batteries can be made significantly safer and more practical by utilizing CO2/oxalate conversions instead of O2/peroxide or O2/hydroxide ones, in the positive electrode. Metal-air batteries, such as the Li-air one, may have very large energy densities, comparable to that of gasoline, theoretically allowing for long range all-electric vehicles. There are, however, still significant challenges, especially related to the safety of their underlying chemistries, the robustness of their recharging and the need of supplying hi…
Mixed Polyanionic NaFe$_{1.6}$V$_{0.4}$(PO$_{4}$)(SO$_{4}$)$_{2}$@CNT Cathode for Sodium-ion Batteries: Electrochemical Diffusion Kinetics and Distribution of Relaxation Time Analysis at Different Temperatures
