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fuel cell

A fuel cell is a device that converts the chemical energy of a fuel directly into electrical energy.

The working principle is basically the same as that of a general battery, except that the active materials at both poles are stored outside the battery. The active materials of the battery are generally liquid or gas. Its electrodes are different from those of general batteries, and mainly use porous gas diffusion electrodes. As long as the active materials, i.e., fuel and oxidant, are continuously supplied, the battery can continuously generate electricity.

To ensure the normal operation of the battery, there must also be an auxiliary system to remove the reaction products-water and heat.

Batteries can be divided into high-temperature (above 500°C), medium-temperature (about 200°C), and room-temperature fuel cells according to the operating temperature; they can be divided into hydrogen-oxygen (air), hydrazine-air (oxygen), methanol-air (oxygen) and hydrocarbon-air fuel cells according to the fuel.

The advantages of the battery are:

It is not limited by the Carnot cycle followed by general heat engines, and the actual efficiency can reach 50~70%. When the power supply time is more than ten hours, the specific energy is much greater than other chemical power sources. It can be made into power sources of various powers (tens of milliwatts to tens of megawatts), and can be continuously powered, with a service life of up to thousands of hours.

Since the auxiliary system of the battery is complex, most of them require precious metal catalysts and are expensive, so they are limited to some special uses. Such as manned spacecraft, buoys, lighthouses, unmanned weather stations, submarines and some military communication equipment.

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