Modular pressurized hotbox for use and substitution in a variety of pressurized electrochemical applications to include reversible solid oxide electrolyzer and fuel cells, energy storage systems, renewable fuel production, solid-state hydrogen pumping and liquefaction, and oxygen transport membranes. This is enabled by mixed electronic and ionic conducting compositions of vanadia-yttria and vanadia-calcia stabilized zirconia and a dry powder method of manufacture for ceramic core stacks.

Modular pressurized hotbox for use and substitution in a variety of pressurized electrochemical applications to include reversible solid oxide electrolyzer and fuel cells, energy storage systems, renewable fuel production, solid-state hydrogen pumping and liquefaction, and oxygen transport membranes. This is enabled by mixed electronic and ionic conducting compositions of vanadia-yttria and vanadia-calcia stabilized zirconia and a dry powder method of manufacture for ceramic core stacks.

The present invention provides fuel cell stacks comprising effective means to maintain the fuel cell stacks at a constant temperature using plates mated to at least one face of the stack and in contact with the edges of the repeat and non-repeat layers while making use of the phase change of working-fluids such as water or water-organic species mixtures for heat transfer. Also provided are processes for maintaining said fuel cell stacks at a constant temperature by adjusting the flow rate and pressure of the cooling fluid so that both liquid and vapor are present at the same time.

The present invention provides fuel cell stacks comprising effective means to maintain the fuel cell stacks at a constant temperature using plates mated to at least one face of the stack and in contact with the edges of the repeat and non-repeat layers while making use of the phase change of working-fluids such as water or water-organic species mixtures for heat transfer. Also provided are processes for maintaining said fuel cell stacks at a constant temperature by adjusting the flow rate and pressure of the cooling fluid so that both liquid and vapor are present at the same time.

A fuel cell stack includes: a first fuel cell and a second fuel cell, each of which has a structure in which a solid oxide electrolyte layer having oxygen ion conductivity is provided between two electrode layers; and an interconnector that is provided between the first fuel cell and the second fuel cell and has a separator made of a metal material, wherein the interconnector has a first metal porous part and a first gas passage on a first face of the separator on a side of the first fuel cell, wherein the interconnector has a second metal porous part and a second gas passage on a second face of the separator on a side of the second fuel cell.

A fuel cell stack includes: a first fuel cell and a second fuel cell, each of which has a structure in which a solid oxide electrolyte layer having oxygen ion conductivity is provided between two electrode layers; and an interconnector that is provided between the first fuel cell and the second fuel cell and has a separator made of a metal material, wherein the interconnector has a first metal porous part and a first gas passage on a first face of the separator on a side of the first fuel cell, wherein the interconnector has a second metal porous part and a second gas passage on a second face of the separator on a side of the second fuel cell.

An air supply system, comprising at least two air blowers and at least two communication valves; wherein one air blower is connected to a main air passage through the corresponding communication valve; and at least one other is connected to a reformer air passage and a stack air passage through at least one other communication valve, respectively. At least two air blowers are provided to connect the at least two communication valves.

A fuel reformer module (8005) for initiating catalytic partial oxidation (CPOX) to reform a hydrocarbon fuel oxidant mixture (2025, 3025) to output a syngas reformate (2027) to solid oxide fuel cell stack (2080, 5040). A solid non-porous ceramic catalyzing body (3030) includes a plurality of catalyst coated fuel passages (3085). A thermally conductive element (9005, 10005, 11005, 13005), with a coefficient of thermal conductivity of 50 W/m° K or greater is thermally conductively coupled with the catalyzing body. A first thermal sensor (8030) is thermally conductively coupled with the thermally conductive element. A second thermal sensor is thermally conductively coupled with a surface of the fuel cell stack. A control method independently modulates an oxidant input flow rate, based on first thermal sensor signal values, a hydrocarbon fuel input flow rate, based on second thermal sensor signal values.

A fuel reformer module (8005) for initiating catalytic partial oxidation (CPOX) to reform a hydrocarbon fuel oxidant mixture (2025, 3025) to output a syngas reformate (2027) to solid oxide fuel cell stack (2080, 5040). A solid non-porous ceramic catalyzing body (3030) includes a plurality of catalyst coated fuel passages (3085). A thermally conductive element (9005, 10005, 11005, 13005), with a coefficient of thermal conductivity of 50 W/m° K or greater is thermally conductively coupled with the catalyzing body. A first thermal sensor (8030) is thermally conductively coupled with the thermally conductive element. A second thermal sensor is thermally conductively coupled with a surface of the fuel cell stack. A control method independently modulates an oxidant input flow rate, based on first thermal sensor signal values, a hydrocarbon fuel input flow rate, based on second thermal sensor signal values.

An electrochemical cell includes a fuel electrode, an air electrode containing a perovskite type oxide as a main component, the perovskite type oxide being represented by a general formula ABO.sub.3 and containing La and Sr at an A site, and a solid electrolyte layer arranged between the fuel electrode and the air electrode. The air electrode includes a first portion and a second portion, the first portion being located on a side opposite to the solid electrolyte layer, the second portion being located on the solid electrolyte layer side. A first ratio of an La concentration to an Sr concentration detected at the first portion through Auger electron spectroscopy is at least 1.1 times a second ratio of an La concentration to an Sr concentration detected at the second portion through Auger electron spectroscopy.