Detailed explanation of the principle of fuel power battery

The principle of a fuel power battery is an electrochemical device, and its composition is the same as that of a general battery. The single cell is composed of positive and negative electrodes (the negative electrode is the fuel electrode and the positive electrode is the oxidizer electrode) and an electrolyte. The difference is that the active material of the general battery is stored inside the battery, therefore, the battery capacity is limited. The positive and negative electrodes of a fuel power battery do not contain active materials, but are only catalytic conversion elements. Therefore, the fuel power battery is a veritable energy conversion machine that converts chemical energy into electrical energy. When the battery is working, the fuel and oxidant are supplied from the outside and react. In principle, as long as the reactants are continuously input and the reaction products are continuously eliminated, the fuel power cell can continue to generate electricity. Here, a hydrogen-oxygen fuel power cell is taken as an example to illustrate the reaction principle of a fuel power cell hydrogen-oxygen fuel power cell. This reaction is the reverse process of electrolysis of water. The electrode should be: negative electrode: H2+2OH-→2H2O+2e- positive electrode: 1/2O2+H2O+2e-→2OH- battery reaction: H2+1/2O2u003du003dH2O In addition, only the fuel power battery body cannot work. There must be a set of corresponding auxiliary systems, including reactant supply system, heat rejection system, drainage system, electrical performance control system and safety devices. A fuel power cell is usually composed of an electrolyte plate forming an ion conductor, a fuel electrode (anode) and an air electrode (cathode) arranged on both sides, and gas flow paths on both sides. The purpose of the gas flow path is to make fuel gas and air ( Oxidant gas) can pass in the flow path. In practical fuel power cells, because of the different working electrolytes, the types of ions related to the reaction through the electrolyte are also different. The reaction between PAFC and PEMFC is related to hydrogen ion (H+). The reaction that occurs is: Fuel electrode: H2u003du003d2H++2e-(1) Air electrode: 2H++1/2O2+2e-u003du003dH2O(2) Overall: H2+1/2O2u003du003dH2O (3) In the fuel electrode, H2 in the supplied fuel gas is decomposed into H+ and e-, and H+ moves into the electrolyte to react with O2 supplied on the air electrode side. e- Through the external load circuit, it returns to the air electrode side and participates in the reaction on the air electrode side. A series of examples of reactions have resulted in e- passing through the external circuit uninterruptedly, thus constituting power generation. And from the reaction formula (3) in the above formula, it can be seen that the H2O generated by H2 and O2 has no other reaction, and the chemical energy of H2 is transformed into electric energy. But in fact, there is a certain resistance accompanying the reaction of the electrode, which will cause part of the heat energy to appear, thereby reducing the ratio of conversion into electrical energy. The group of batteries that cause these reactions are called modules, and the voltage that appears is usually less than one volt. Therefore, in order to obtain a large output, a method of multi-layer stacking of components is required to obtain a high-voltage stack. The electrical connection between the components and the separation between the fuel gas and the air are made of so-called separators with gas flow paths on the upper and lower sides. The separators of PAFC and PEMFC are made of carbon materials. The output of the stack is determined by the product of the total voltage and current, and the current is proportional to the reaction area in the battery. The electrolyte of PAFC is a concentrated phosphoric acid aqueous solution, while the electrolyte of PEMFC is a membrane of a proton conductive polymer system. The electrodes all use carbon porous bodies. In order to promote the reaction, Pt is used as a catalyst. The CO in the fuel gas will cause poisoning and reduce the electrode performance. For this reason, the amount of CO contained in the fuel gas must be restricted in PAFC and PEMFC applications, especially PEMFC that works at low temperatures should be strictly restricted. The basic composition and reaction principle of the phosphoric acid fuel power cell are: the fuel gas or city gas is added with water vapor and sent to the reformer to convert the fuel into a mixture of H2, CO and water vapor, and the CO and water are further in the shift reactor The catalyst is converted into H2 and CO2. The fuel gas after such treatment enters the negative electrode (fuel electrode) of the fuel stack, and at the same time transports oxygen to the positive electrode (air electrode) of the fuel stack for chemical reaction, and the use of the catalyst quickly generates electric energy and heat. Compared with PAFC and PEMFC, high-temperature fuel power cells MCFC and SOFC do not require catalysts. Coal gasification gas with CO as an important component can be directly used as fuel, and it is also easy to use its high-quality exhaust to form combined cycle power generation. Disclaimer: Some pictures and content of articles published on this site are from the Internet. 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