In recent years, portable electronic devices, such as cellular phones, personal digital assistants, note type personal computers, portable audios, and portable visual instruments, have been developed in terms of multiple functions and high performance. With such development, demands for a larger capacity of battery cells for drive power for the above devices have been increased. Conventionally, as such battery cells for drive power for the above portable electronic devices, lithium batteries and nickel-cadmium batteries are used. However, the respective capacities of these batteries approach the limit, and a dramatic increase in the capacity may not be expected. Then, instead of such lithium batteries and nickel-cadmium batteries, fuel cells which have high energy density and a possibility for a larger capacity are developed actively.
Further, fuel cells generate electric power from hydrogen and oxygen in air, and efficiency in generating electric power theoretically is high. Accordingly, the fuel cells can save energy. In addition, since fuel cells discharge only water as excretions at the time of generation of electricity, and do not discharge carbon dioxides and nitrogen oxides, they are evaluated as a eco-friendly power generating method. Consequently, the fuel cells are expected as a powerful card for solving energy and environment concern on a global basis.
Such a fuel cell has typically the following structure. A solid polymer electrolyte membrane which employs a solid polymer ion exchange membrane, a solid oxide electrolyte membrane which employs yttria-stabilized zirconia (YSZ), or the like is sandwiched between a fuel electrode and an air electrode (oxygen electrode), and the resulting laminated structure is further sandwiched between a pair of separators so as to form one cell. Further, in the cell, a hydrogen flow passage and an air flow passage are disposed. The hydrogen flow passage is configured to supply hydrogen as one example of fuel gas to the fuel electrode, and the air flow passage is configured to supply air to the air electrode. When hydrogen and air (oxygen) are supplied through these flow passages to the fuel electrode and the air electrode respectively, electricity is generated by an electrochemical reaction.
However, the fuel cell needs infrastructure development for supplying fuel, for example, hydrogen. Further, in methanol which is comparatively easily available as a fuel, there is a problem that it takes years to establish a distribution system for methanol.
Then, in order to cope with such problems, Patent Document 1 teaches a technique to dispose in a fuel cell body a hydrogen producing member which produces hydrogen by making predetermined metal fine particles react with water, and to supply the hydrogen produced by this hydrogen producing member to a fuel electrode. According to this technique, water produced by electricity generation in the fuel cell body is supplied as water required for hydrogen generation. Accordingly, it is not required to carry water required for hydrogen generation. The hydrogen produced by the hydrogen producing member is supplied to the fuel electrode, and then, in the fuel electrode, the supplied hydrogen is oxidized so as to generate electricity, whereby water is reproduced again, and the above cyclical processes are utilized. As a result, it is not required to supply hydrogen from the outside, and it becomes possible to continue the electricity generating action.