Abstract: A direct methanol type fuel cell system provided with a tank for storing an antifreeze that is injected into at least said unit cell or a cell stack and held in place at the time of stand-by operation of the direct methanol type fuel cell system. At the time of starting operation an oxidant gas is supplied to the cathode side and the antifreeze is removed from the unit cell or the cell stack. After starting operation, the passage between the antifreeze tank and the unit cell or the cell stack is closed and an aqueous solution of methanol is supplied as liquid fuel from a fuel tank to the anode side.

Abstract: A liquid fuel direct supply fuel cell system capable of being operated under optimal conditions. A plurality of cells each having an anode and a positive electrode disposed oppositely through an electrolytic film and being fed, respectively, with liquid fuel and oxidizing agent gas are connected in series as a power generating section (11), which is then provided with a sensor section (12) for detecting the concentration of the liquid fuel in association with a temperature detected by a temperature detecting element thus producing a cell stack (1), and a controller (7) controls high concentration fuel supply amount from a high concentration fuel tank (5) to a fuel tank (2) based on an output signal from the sensor section (12).

Abstract: Elution of a fuel electrode material into a fuel in a direct methanol fuel cell is monitored. The elution arises resulting from elution of a perfluorosulfonic acid polymer in the fuel electrode into the fuel in a high-concentration fuel equal to or more than 2 M or at an operating temperature equal to or more than 80° C. The electrode catalyst elutes into the fuel and the characteristic degrades. Operating conditions of the fuel cell, i.e., the fuel concentration and the operating temperature are limited to be less than 2 M and 80° C. or less, respectively. In addition, the elution characteristic is evaluated at the time of manufacture of the fuel cell and quality control is conducted. Further, existence of the elution is detected by a color of the fuel etc., and when the elution is detected, the upper limits of the operating temperature and the fuel concentration are decreased, so that further elution is prevented.

Abstract: A direct methanol fuel cell is provided in a fuel tank, and a liquid fuel is supplied to a fuel electrode with convection through a duct which vertically passes through a surface of a separator. Air is supplied to a duct for air supply, the duct being provided to the separator, from a blower.

Abstract: A secondary battery is connected to a fuel cell, the fuel cell is disconnected from a load when the output of the fuel cell falls, and the load is activated with the secondary battery. When the remaining capacity of the secondary battery decreases and becomes less than or equal to a first level, an indicator for indicating running out of fuel is turned on to require refueling. When the remaining capacity becomes less than or equal to a second level, the load is disconnected even from the secondary battery.

Abstract: A liquid fuel direct supply fuel cell system capable of being operated under optimal conditions. A plurality of cells each having an anode and a positive electrode disposed oppositely through an electrolytic film and being fed, respectively, with liquid fuel and oxidizing agent gas are connected in series as a power generating section (11), which is then provided with a sensor section (12) for detecting the concentration of the liquid fuel in association with a temperature detected by a temperature detecting element thus producing a cell stack (1), and a controller (7) controls high concentration fuel supply amount from a high concentration fuel tank (5) to a fuel tank (2) based on an output signal from the sensor section (12).

Abstract: A direct methanol type fuel cell system provided with a tank for storing an antifreeze that is injected into at least said unit cell or a cell stack and held in place at the time of stand-by operation of the direct methanol type fuel cell system. At the time of starting operation an oxidant gas is supplied to the cathode side and the antifreeze is removed from the unit cell or the cell stack. After starting operation, the passage between the antifreeze tank and the unit cell or the cell stack is closed and an aqueous solution of methanol is supplied as liquid fuel from a fuel tank to the anode side.

Abstract: A liquid-fuel feed fuel cell disclosed with a unit cell that has a structure in which a negative electrode and a positive electrode are opposed with a polymer electrolyte having a proton conductivity interposed between them. A liquid fuel is supplied to the negative electrode and air is supplied to the positive electrode. The liquid-fuel feed fuel cell has a cell stack where unit cells are stacked. Additionally, an operation monitoring method for monitoring the operation and an operation monitoring device are disclosed. To prevent degradation, the liquid-fuel feed fuel cell has at least one of the following functions: increasing the supply of air or liquid fuel, issuing an alarm, decreasing the output current, and stopping the operation of the fuel cell when it is detected that the potential between the negative and positive electrodes monitored for at least one cell is below a predetermined negative potential.