Multilayered Electrolyte Research Articles

Contrary interfacial effects for textured and non-textured multilayer solid oxide electrolytes

We report a negative and a positive interfacial effect for textured and non-textured polycrystalline Ce0.8Sm0.2O2−δ/Al2O3 multilayered solid electrolytes which are due to differences in microstructures.

A gel-ceramic multi-layer electrolyte for long-life lithium sulfur batteries.

A newly designed gel-ceramic multi-layer electrolyte has been used as the separator and electrolyte for lithium sulfur (Li-S) batteries. The Li-S cells, free of the shuttle effect, exhibit superior electrochemical performance. With almost no self-discharge, the cell demonstrates an initial discharge specific capacity of up to 725 mA h g(-1) and remains at 700 mA h g(-1) after 300 cycles at the C/2 rate.

Multi-layer thin-film electrolytes for metal supported solid oxide fuel cells

A key to the development of metal-supported solid oxide fuel cells (MSCs) is the manufacturing of gas-tight thin-film electrolytes, which separate the cathode from the anode. This paper focuses the electrolyte manufacturing on the basis of 8YSZ (8 mol.-% Y2O3 stabilized ZrO2). The electrolyte layers are applied by a physical vapor deposition (PVD) gas flow sputtering (GFS) process. The gas-tightness of the electrolyte is significantly improved when sequential oxidic and metallic thin-film multi-layers are deposited, which interrupt the columnar grain structure of single-layer electrolytes. Such electrolytes with two or eight oxide/metal layers and a total thickness of about 4 μm obtain leakage rates of less than 3 × 10−4 hPa dm3 s−1 cm−2 (Δp: 100 hPa) at room temperature and therefore fulfill the gas tightness requirements. They are also highly tolerant with respect to surface flaws and particulate impurities which can be present on the graded anode underground. MSC cell tests with double-layer and multilayer electrolytes feature high power densities more than 1.4 W cm−2 at 850 °C and underline the high potential of MSC cells.

Multilayer electrolyte cell: A new tool for identifying electrochemical performances of high voltage cathode materials

Multilayer electrolyte cell (MEC) was designed and developed as a new tool for investigating electrode/electrolyte interfacial reactions in a battery system. The MEC consists of two liquid electrolytes separated by a solid electrolyte which prevents electrolyte crossover while selectively transporting Li+ ions. The MEC successfully reproduced the performance of LiFePO4 comparable with that obtained from coin cells. In addition, the origin of capacity fading in LiNi0.5Mn1.5O4full-cell (with graphite negative electrode) was studied using the MEC. The performance of LiNi0.5Mn1.5O4 MEC full-cell was superior to that of coin full-cell by eliminating the Mn dissolution problem on graphite negative electrode as evidenced by transmission electron microscopyanalysis. The MEC can be a strong tool for identifying the electrochemical performances of future high voltage positive electrode materials and their electrode/electrolyte interfacial reactions.

New buffer layer material La(Pr)CrO3for intermediate temperature solid oxide fuel cell using LaGaO3-based electrolyte film

Abstract

Doped zirconia and ceria-based electrolytes for solid oxide fuel cells: a review

Zirconia and ceria possess fluorite-type structure and conduct electricity by means of oxide ion transport through the lattice. On doping, vacancies created at the oxygen site make way for the neighbouring oxygen atoms to ‘hop’ in the direction of electric field. Among doped zirconia, 8 mol% yttria-stabilized zirconia and 9–11 mol% scandia-stabilized zirconia exhibit the highest conductivity. Ceria electrolytes require lower operational temperature (~600–800°C) compared to that of zirconia electrolytes (800–1000°C). With improvement in the processing and fabrication techniques, researchers have developed thinner electrolytes to minimize ohmic polarization and enhance the ionic conductivity enabling operation at lower temperatures (~400–600°C). But such electrolytes are required to be supported on electrodes (anode or cathode) and in later times heterostructured bi-, tri- and multi-layered electrolyte films have been constructed. Since the last decade, development of submicron grain size electrolytes and ultimately two-phase materials with nanodimension grain size has shown improvement in ionic conductivity as well as low-temperature workability. The article reviews the turning points in the technological development of fluorite-based solid oxide fuel cell electrolytes from single-phase micrometer dimension grain size to recently developed two-phase nanocomposites and nanowires, and the successful achievement of its workability at low temperatures (~450°C).

Improvement of Micro Tubular SOFCs using Multi-Layered Electrolyte

Fabrication technology of multi-layered electrolyte for micro tubular SOFCs has been developed. Sc2O3 stabilized ZrO2(ScSZ) and Gd2O3-doped CeO2 (GDC) was selected for the electrolyte materials and a GDC-ScSZ-GDC multi-layered electrolyte was successfully prepared using multiple dip coating and co-firing technique. The thickness of each layer for the electrolyte was about 3, 3, and 12 micron, respectively. The cell performance test showed the open circuit voltage (OCV) of over 1 V at 600oC or higher, while a SOFC with 10 micron thick GDC electrolyte showed the OCV of 0.78 V at 600oC. The cell performance of 0.35 Wcm-2 @ 0.7 V was obtained at the operating temperature of 650 oC.

Improvement of Micro Tubular SOFCs using Multi-layered Electrolyte

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Fabrication of Multi-Layered Electrolyte for Micro Tubular SOFCs

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Fabrication and Characterization of Microtubular SOFCs with Multilayered Electrolyte

Multilayered electrolytes for microtubular solid-oxide fuel cells (SOFCs) have been prepared and their electrochemical properties investigated. SC 2 O 3 -stabilized ZrO 2 (ScSZ) and Gd 2 O 3 -doped CeO 2 (GDC) were selected for the electrolyte materials; the multilayered electrolyte of GDC-ScSZ-GDC was successfully prepared on an anode tube (1.8 mm diameter) using multiple dip coating and a cofiring technique. The thickness of each electrolyte layer was about 3, 3, and 12 μm, respectively. The cell performance test showed an open-circuit voltage (OCV) of over 1 V at 600°C or higher temperature for the SOFC with a multilayered electrolyte, while a SOFC with a 12 μm thick GDC electrolyte showed an OCV of 0.84 V at 600°C. The cell performances of 0.35 W cm -2 at 0.7 V and 0.27 W cm -2 at 0.8 V were obtained for the SOFC with multilayered electrolyte at the operating temperature of 650°C.

Blocking of Electronic Current through a Ce[sub 0.9]Gd[sub 0.1]O[sub 1.95] Electrolyte Film by Growth of a Thin BaCe[sub 1−x]Gd[sub x]O[sub 3−α] Layer

A Bace 1-x Gd x O 3-α (BCG) layer was grown between Ce 0.9 Gd 0.1 O 1.95 (GDC) layers. This was accomplished by a solid-state reaction of a BaO layer with the GDC layer. In the multilayered GDC/BCG/GDC electrolyte film, all layers showed dense and homogeneous junction structure. When a hydrogen-air fuel cell with the multilayered electrolyte cell was tested at 550-800°C, the BCG layer could partially block the electronic current through the cell. The resulting open-circuit voltage and power density were increased by a maximum of 127 mV and 202 mW cm -2 , respectively, compared with those for a single-layered GDC electrolyte cell under the same conditions.

Comparative Performance of Anode-Supported SOFCs Using a Thin Ce0.9Gd0.1O1.95 Electrolyte with an Incorporated BaCe0.8Y0.2O3 − α Layer in Hydrogen and Methane

Multilayered (GDC∕BCY∕GDC) electrolytes were prepared by tape casting on a anode support. The overall electrolyte thickness ranged from , including a thick BCY layer. When the multilayered electrolyte cell was tested with hydrogen at the anode and air at the cathode in the temperature range of , it yielded open-circuit voltages (OCVs) of , which were higher than the OCVs of obtained for a single-layered GDC electrolyte cell under the same conditions. The corresponding peak power densities reached 273, 731, and at 500, 600, and , respectively. The multilayered electrolyte cell could also be applied to direct methane solid oxide fuel cell (SOFC) and single-chamber SOFC operating in a mixture of methane and air. These SOFCs yielded OCVs of and reasonable power densities without coking.

Reduction in the operating temperature of solid oxide fuel cells—potential use in transport applications

Abstract The development of solid oxide fuel cells (SOFC) offers new perspectives, in particular as auxiliary power units for vehicle applications. The elaboration of thin electrolyte layers is the main challenge in order to reduce their operating temperature. A brief review of the deposition techniques and of the potential electrolytes is presented. A relatively new technique, Atomic Layer Deposition (ALD), allows to produce thin, dense and homogeneous layers, i.e. zirconia or zirconia-based thin layers can be deposited on different substrates. The interest of elaborating bi- or multi-layer electrolytes is outlined.

Polarization inventory diagrams

The significance in electrochemistry of the term ‘polarization’ is carefully explained. Several diverse effects contribute to the overall polarization and the magnitudes of the corresponding overvoltages may be calculated via equations that are presented. An informative graphical method of presenting data on the evolution of the individual overvoltages during voltammetry is described and exemplified. The diagram may be constructed from experimental data or as part of a predictive exercise using either digital simulation or convolutive modelling. Four examples of these polarization inventory diagrams are presented. Among the features that may be factored into the diagrams are various voltammetric protocols, electrode reactions of any degree of reversibility, arbitrary transfer coefficient, diffusion coefficient diversity, varied cell geometries, transport by diffusion and/or migration, first-order homogeneous reactions, uncompensated resistance, and multi-layered electrolyte solutions.

Comparison of Power Densities and Chemical-Potential Variation in SOFC’s with Multi-Layer and Single-Layer Oxide Electrolytes

Comparison of Power Densities and Chemical-Potential Variation in SOFC’s with Multi-Layer and Single-Layer Oxide Electrolytes

Sputter-deposited medium-temperature solid oxide fuel cells with multi-layer electrolytes

The deposition, interfacial impedances, and characteristics of solid oxide fluel cells (SOFC) with thin-film multi-layer electrolytes are described. The cell layers — a 1 μm thick AgYSZ cermet cathode, a 15 to 20 μm thick NiYSZ anode — were deposited on porous alumina by reactive magnetron co-sputtering of metal tartgets in ArO 2 mixtures. The effect of adding Y-stabilized Bi 2O 3 (YSB) and Y-doped CeO 2 (YDC) layers at the ytria-stabilized-zirconia (YSZ) electrolyte surfaces was investigated. The open circuit voltage of the H 2/H 2O (3%), NiYSZ / electrolyte / AgYSZ, air fuel cells tested at 750°C was 0.78—0.85 V, less than expected theoretically, indicating some porosity in the electrolyte layers. The cell resistance was 4.5 Ω cm 2 for a YSZ electrolyte, due mainly to the electrode interfacial resistances, and the maximum power density was 35 mW / cm 2. Adding a 60 nm-thick YSB layer at the YSZ/AgYSZ interface reduced the air electrode resistance from ≈1.4 to 0.45 Ω cm 2, leading to an increase in the maximum power density to ≈50 mV/cm 2. Adding a 100 nm-thick YDC layer at the NiYSZ/ YSZ interface further increased the maximum power density to 110 mW/cm 2 at a cell resistance of 1.6 μ cm 2. The three-layer YSB/YSZ/YDC electrolyte thus resulted in a factor-of-three increase in power density over a YSZ electrolyte.