Abstract: The fuel cell system of the present disclosure includes: a fuel cell that includes a membrane electrode assembly including a proton conducting ceramic electrolyte membrane, a cathode disposed on a first surface of the electrolyte membrane, and an anode disposed on a second surface of the electrolyte membrane, the fuel cell generating electric power through an electrochemical reaction using a fuel gas and an oxidant gas; a power source that applies a voltage to the fuel cell; and a controller. In a shutdown process, the controller controls the power source to apply the voltage to the fuel cell such that a terminal voltage of the fuel cell is equal to or higher than an open circuit voltage of the fuel cell.

Abstract: A fuel cell system according to the present disclosure includes: a solid oxide fuel cell that produces electricity from an electrochemical reaction by using a fuel and air and that includes a membrane electrode assembly including a proton-conductive electrolyte membrane, a cathode disposed on a first main surface of the electrolyte membrane, and an anode disposed on a second main surface of the electrolyte membrane; and a controller. In the operation stop process for stopping operation of the fuel cell system, the controller is configured to control supply of the fuel at a higher flow rate than the flow rate of the fuel consumed in the solid oxide fuel cell in an open circuit state.

Abstract: The electrochemical apparatus of the present disclosure includes a first stack that includes an oxide ion conductor as an electrolyte and decomposes water vapor to generate hydrogen and oxygen, a second stack that includes a proton conductor as an electrolyte and separates the hydrogen generated in the first stack from a gas mixture of the hydrogen and the water vapor that has not been decomposed in the first stack, and a heat insulation material that covers the first stack and the second stack.

Abstract: An electrochemical cell of the present disclosure includes a first cell and a second cell. The first cell includes a first electrolyte layer containing an oxide ion conductor. The second cell includes a second electrolyte layer containing a proton conductor, and the second cell is disposed to face the first cell.

Abstract: An electrochemical cell includes a first electrolyte layer containing an oxide-ion conductor, a second electrolyte layer containing a proton conductor, a first electrode which is disposed between the first electrolyte layer and the second electrolyte layer and in contact with a first principal surface of the first electrolyte layer and a first principal surface of the second electrolyte layer and into which a gas flows, a second electrode which is provided on a second principal surface of the first electrolyte layer and which generates oxygen, and a third electrode which is provided on a second principal surface of the second electrolyte layer and which generates hydrogen.