Basic principles and development of fuel cells
A fuel cell is an energy conversion device. It is based on the principle of electrochemistry, that is, the working principle of a primary battery. The chemical energy stored in the fuel and the oxidant is isothermally converted into electric energy, and the actual process is a redox reaction. The fuel cell is mainly composed of four parts, namely an anode, a cathode, an electrolyte, and an external circuit. The fuel gas and the oxidizing gas are respectively introduced from the anode and the cathode of the fuel cell. The fuel gas emits electrons on the anode, and the electrons are conducted to the cathode through an external circuit and combined with the oxidizing gas to generate ions. Under the action of an electric field, the ions migrate to the anode through the electrolyte, react with the fuel gas, form a loop, and generate an electric current. At the same time, the fuel cell generates a certain amount of heat due to its own electrochemical reaction and the internal resistance of the battery. The cathodes of the battery, in addition to conducting electrons, also act as a catalyst for the redox reaction. When the fuel is a hydrocarbon, the anode is required to have a higher catalytic activity. The anodes and cathodes are usually porous in order to facilitate the passage of reaction gases and product discharge. The electrolyte functions to transfer ions and separate the fuel gas and the oxidizing gas. In order to block the mixing of the two gases, the internal short circuit of the battery is caused, and the electrolyte is usually a dense structure.