The fuel cell is actually a chemical reactor that converts the chemical energy of the fuel homogeneizer directly into electrical energy. It does not have a prime drive drive power plant on a conventional power generation device, and there is no direct combustion process. Fuels and oxidants are constantly input from the outside, which can constantly output electrical energy. Its reactants are typically fuel such as hydrogen and oxygen, and its by-products are generally harmless water and carbon dioxide. The operation of the fuel cell is not only based on the battery itself, and the fuel and oxidant supply and the reaction product discharge are also required to form a complete fuel cell system with the battery stack.
The actual fuel cell needs to have a sufficiently high current density, thus increasing the rate of the electrode reaction. The reaction in the fuel cell occurs on the surface of the electrode (strictly said to be electrode, gas, and electrolyte composition), hydrogen is reacted in an anode generating electrode, and the generated electrons and protons reach the cathode through the outer circuit and electrolyte, and in the cathode Reacts with oxygen to form water. Electrical energy outputs electrical energy when electron passes through an external circuit.
The main factor affecting the electrode reaction rate is the catalytic activity and electrode surface area. The electrode of the fuel cell is not a simple solid electrode, but a so-called porous electrode. The surface area of the porous surface is 1028 times the electrode geometric area. The catalytic activity of the electrode is particularly important for low temperature fuel cells because the rate of electrode is low at low temperatures.
In addition, the electrodes of the fuel cell also require good conductivity, high temperature and corrosion resistance.
The main function of the electrolyte in the fuel cell is to provide an ion, conductive, and two-pole reactive substance required for electrode reactions. Unlike general electrolytes, electrolytes in the fuel cells are or they have no fluidity, or are immobilized in a porous matrix.
The electrolyte of the PEMFC is a solid polymer film that allows the proton to pass, so it is called a proton exchange membrane.
The electrolyte of the AFC is a KOH solution, depending on the operating temperature of the battery (50-200 cc), the concentration of KOH has changed significantly (35% and 85%). KOH was adsorbed in the asbestos matrix. KOH and COZ reactively generate Kz Co having a lower solubility, resulting in clogging, and CO2 in the reaction gas needs to be removed.
PAFC is electrolyte with a phosphoric acid close to 100%, immersed in a porous SiC ceramic. The thermostability of concentrated phosphoric acid is good, and the water vapor generated by the electrode reaction can be absorbed, so the water management of PAFC is simple.
The electrolyte of MCFC is mixed carbonate (Lie Co, -K2 CO,), matrix LIAMO2 ceramic, conductive ions are CO; one.
The electrolyte of SOFC is a porous metal oxide, ie Y2O, stable ZrO2, and electrically conductive ions are O2.
Third, bipolar plate
Cathodes, anodes and electrolytes constitute a single fuel cell with a working voltage of about 0. 7V. In order to obtain the actual needs, several, dozens of or even hundreds of fuel cells must be connected, called the battery stack. Two adjacent fuel cells are connected by a bipolar plate. One side of the bipolar plate is connected to the anode of the previous fuel cell, and the other side is connected to the cathode of the rear fuel cell (so as a bipolar plate).
There are three main functions of the bipolar plate, i.e., the current collecting the fuel cell, supplies the reaction gas to the electrode to prevent the penetration of the reaction material between the two poles. In addition, the bipolar plate also supports the effect of reinforcing the fuel cell.
The bipolar plate material of the low temperature (less than 300 cc) fuel cell is usually made of stainless steel or conductive ceramics for graphite, high temperature fuel cell. Regardless of the material, the design and production of the bipolar plate are critical.
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Shenzhen Geerady New Energy Co., Ltd NO.7888, SHENZHEN, CHINA