Anodes for Carbon‐Fueled Solid Oxide Fuel Cells

Abstract

Solid oxide fuel cells (SOFCs) have been considered as one of the most promising technologies for high‐efficiency electrical energy generation using a variety of fuels, including hydrogen, natural gas, biogas, carbon monoxide, liquid hydrocarbons and solid carbon. Carbon‐fueled SOFCs (CF‐SOFCs) potentially have the highest volume power density because solid carbon has a fuel energy density of 23.95 kWh L−1, which is approximately 10 times higher than that of liquid hydrogen. However, the reactivity and fluid mobility of carbon is significantly lower than those of gaseous fuels; thus, CF‐SOFCs will be kinetically limited at the anode. Herein, we review the development of anodes in CF‐SOFCs from the perspective of material compositions and microstructures. Challenges and research trends based on the fundamental understanding of the materials science and engineering for anode development in CF‐SOFCs are discussed.

Purified high‐sulfur coal as a fuel for direct carbon solid oxide fuel cells

“…Direct carbon fuel cells (DCFCs) are a promising electrochemical system that converts chemical energy of solid carbonaceous fuels into electricity with very high efficiency and concentrated CO 2 product streams that can be directly collected for industrial use or sequestration . Thermodynamically speaking, DCFCs offer 100% of conversion efficiency and up to 80% in practice, which nearly doubles the typical theoretical and real thermal conversion values found in thermal power plants, respectively .…”

“…Direct carbon fuel cells (DCFCs) are a promising electrochemical system that converts chemical energy of solid carbonaceous fuels into electricity with very high efficiency and concentrated CO 2 product streams that can be directly collected for industrial use or sequestration . Thermodynamically speaking, DCFCs offer 100% of conversion efficiency and up to 80% in practice, which nearly doubles the typical theoretical and real thermal conversion values found in thermal power plants, respectively . Compared with DCFCs with molten hydroxide or carbonate electrolytes, solid oxide electrolyte DCFCs (SO‐DCFCs, or DC‐SOFCs) offer many advantages in terms of high reliability and great fuel flexibility due to all solid‐state construction and gasification‐based fuel delivery mode .…”

“…Coal is a complex heterogeneous conglomerate that usually contains a variety of organic and inorganic impurities. The compatibility problem between coal‐derived solid carbonaceous fuels and the anode of DC‐SOFCs is a major challenge for coal‐based DC‐SOFCs, because the anode materials such as nickel cermets are quite vulnerable to the deleterious and deactivating effects of coal contaminants . Sulfur is the most notorious contaminant among the volatile coal contaminants such as S, P, Cl, As, and Sb in the form of their hydrides .…”

A solid oxide carbon fuel cell operating on pomelo peel char with high power output

“…The direct electrochemical conversion of carbon in DCFCs offers inherently high theoretical and practical efficiencies close to ~100% and ~80%, respectively. In contrast, the thermochemical conversion of carbon to electricity is a multistep process constrained by the Carnot cycle, just providing ~50% and ~40% conversion efficiencies in thermodynamics and thermal power plants, respectively . Meanwhile, DCFCs have the superiority to produce concentrated CO 2 product streams, which could be available for industrial use or sequestration without expensive gas separation and energy intensive purification processes .…”

“…However, DCFCs face a primary challenge of how to effectively deliver the solid carbon particles through the pores of anode to the electrochemically reactive sites on the anode/electrolyte interface . To solve this solid‐to‐solid contact problem, a series of strategies have been proposed and demonstrated, such as using molten hydroxide or carbonate as electrolyte, and molten metals (eg, iron, copper, lead, indium, bismuth, antimony, and tin) as anode . In addition, the hybrid type of DCFC combines a solid oxide electrolyte and a molten carbonate electrolyte to achieve better performances .…”