A ceramic fuel cell in an all solid-state energy conversion device that produces electricity by electrochemically combining fuel and oxidant gases across an ionic conducting oxide. Current ceramic fuel cells use an oxygen-ion conductor or a proton conductor as the electrolyte and operate at high temperatures (>600°C). Ceramic fuel cells, commonly referred to as solid-oxide fuel cells (SOFCs), are presently under development for a variety of power generation applications. This paper reviews the science and technology of ceramic fuel cells and discusses the critical issues posed by the development of this type of fuel cell. The emphasis is given to the discussion of component materials (especially, ZrO2 electrolyte, nickel/ZrO2 cermet anode, LaMnO3 cathode, and LaCrO3 interconnect), gas reactions at the electrodes, stack designs, and processing techniques used in the fabrication of required ceramic structures.

Ceramic Fuel Cells

Materials Challenges in Nuclear Energy

Despite being first demonstrated over 160 years ago, and offering significant environmental benefits and high electrical efficiency, it is only in the last two decades that fuel cells have offered a realistic prospect of being commercially viable. The solid oxide fuel cell (SOFC) offers great promise and is presently the subject of intense research activity. Unlike other fuel cells the SOFC is a solid-state device which operates at elevated temperatures. This review discusses the particular issues facing the development of a high temperature solid-state fuel cell and the inorganic materials currently used and under investigation for such cells, together with the problems associated with operating SOFCs on practical hydrocarbon fuels.

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Solid oxide fuel cells

Progress in material selection for solid oxide fuel cell technology: A review

Present review is aimed at providing a state-of-art development of anode for solid oxide fuel cell (SOFC) with principal emphasis on the materials aspect. The criteria for the anode of SOFC are first presented. The prospects and problems of the currently developed anode materials are elucidated. In particular, the electrochemical properties of the Ni/YSZ cermet anode that is the most commonly employed in the establishment of SOFC stack is described along with various approaches attempted for their improvements. The advantages and disadvantages of other anode materials are compared to offer some insights for the research and development of new generation of anode materials for SOFC.

A review on the status of anode materials for solid oxide fuel cells

Blanket Comparison and Selection Study

Elevated-temperature failure of structural materials (e.g., austenitic stainless steels, low-alloy steels) used in energy-conversion systems can occur by fatigue, creep, or by interactive processes involving creep, fatigue, and environment. The fracture surfaces of these materials exhibit a variety of microstructural features depending upon the type of material, strain rate, temperature, environment, hold times, and sequence of waveshapes. These microstructural observations have been used as a guide in the formulation of generalized damage-rate equations that include interaction between a crack and cavities in a given environment. Crack-propagation rate as well as total life of a fatigue specimen have been calculated by integrating the damage-rate equations over the inelastic strain history of the specimen, and compared with experimental results.

A Mechanistic Model for Time-Dependent Fatigue

Residual thermal stresses and strains, developed during cooling of a SiC whisker-Al2O3 composite, were determined by an experimental neutron diffraction technique and the results were compared with analytically determined values. High compressive residual thermal stresses were generated in the whiskers during cooldown after sintering. Analytical estimates of the residual stresses were obtained by using two self-consistent models: (1) a plane strain composite cylinder model and (2) Eshelby's ellipsoidal inclusion theory. The two models gave almost identical estimates of the stresses and strains in the whiskers. The interpretation of the measured strains in the whiskers by neutron diffraction had some uncertainty because of the lack of a clearly defined crystal structure of SiC.

Determinations of Residual Thermal Stresses in a SiC-Al2O3 Composite Using Neutron Diffraction

Prestorage drying operations of high-burnup fuel may make Zircaloy-4 (Zry-4) fuel cladding more susceptible to failure, especially during fuel handling, transport, and post-storage retrieval. In particular, hydride precipitates may reorient from the circumferential to the radial direction of the cladding during drying operations if a threshold level of hoop stress at or above a corresponding threshold temperature is exceeded. This study indicates that the threshold stress is approximately 75–80 MPa for both nonirradiated and high-burnup stress-relieved Zry-4 fuel cladding cooled from 400°C and, under ring compression at both room temperature and 150°C, that radial-hydride precipitation embrittles Zry-4. Specifically, the plastic tensile hoop strain needed to initiate unstable crack propagation along radial hydrides decreases dramatically from >8% to lt;1% as radial-hydride fraction increases. Lower hydrogen contents (lr;300wppm) appear to be more susceptible to radial-hydride embrittlement compared to hig...

https://www.tandfonline.com/doi/pdf/10.1080/18811248.2006.9711195

Radial-hydride embrittlement of high-burnup zircaloy-4 fuel cladding

This paper summarizes the stress and fracture analyses of a three-layer ceramic composite which is a fundamental building block for the monolithic solid oxide fuel cell currently being developed at Argonne National Laboratory. A small difference in the coefficients of thermal expansion of different layers can result in large stresses and cause cracking parallel to the plane of the layers. A simple fracture model for a three-layer composite has been developed. The cracking behavior predicted by the model is in reasonably good agreement with the fabrication experience to date.

Saurin Majumdar

Papers

Blanket Comparison and Selection Study

A Mechanistic Model for Time-Dependent Fatigue

Determinations of Residual Thermal Stresses in a SiC-Al2O3 Composite Using Neutron Diffraction

Radial-hydride embrittlement of high-burnup zircaloy-4 fuel cladding

Stress and Fracture Behavior of Monolithic Fuel Cell Tapes