Principles of the battery

In the chemical cell, chemical energy directly into electricity through the battery is carried 92P1101 out within the spontaneous oxidation, reduction and other chemical reactions the result of the reaction were carried out in two electrodes. Negative active material from the more negative potential and a stable reducing agent in the electrolyte composition, such as zinc, cadmium, lead active metals and hydrogen or hydrocarbons. Positive active material from a more positive potential in the electrolyte composition of a stable oxidizing agent, such as manganese dioxide, lead dioxide, nickel oxide and other metal oxides, oxygen or air, halogens and their salts, oxygen-containing acid and its salts, etc. . Electrolyte is a good ionic conductivity of the material, such as acids, alkali, salt solution, organic or inorganic non-aqueous solutions, molten salts or solid electrolytes. When the external circuit disconnected, although there potential difference between the two poles (open circuit voltage), but there is no current, stored in the batteries do not convert 92P1089 chemical energy into electrical energy. When the external circuit is closed, the two electrodes under the effect of potential difference that there is current flowing through the external circuit. The same time, the battery inside the electrolyte does not exist due to free electrons, charge transfer must be accompanied by two poles active material and electrolyte interface, the oxidation or reduction reactions, as well as reactants and reaction products of mass transfer. Charge transfer in the electrolyte but also by the migration of ions to complete.92P1087 Thus, within the normal battery charge transfer and mass transfer process is to ensure that the necessary conditions for the normal output of electricity. When charging, the battery inside the transmission power and the direction of mass transfer and discharge exactly the opposite; electrode reaction must be reversible, in order to ensure the opposite direction of mass transfer and mass of the normal electrical processes. Therefore, the electrode reaction reversible constitutes a necessary condition for batteries. Reaction for the Gibbs free energy (coke); F is Faraday's constant = 96500 base = 26.8 ampere-hour; n the equivalent number for the cell reaction. This is the reaction of the battery and battery electromotive force between the basic thermodynamic relations, but also calculation of cell energy conversion efficiency of the basic thermodynamic equation. In fact, when the current flows through the electrodes, the electrode potential must 08K8194 deviate from the thermodynamic equilibrium of the electrode potential, a phenomenon known as polarization. Current density (unit electrode area adopted by the current), the greater the polarization more serious. Polarization phenomenon is caused by the battery energy loss of the important reasons. Polarization for three reasons: ① from the cells caused by the various parts of the polarization resistance is called Ohm polarization; ② from the electrode - electrolyte interface layer caused by charge transfer blocked the process of polarization is called activation polarization; ③ from the electrode - electrolyte interface layer caused by slow mass transfer of polarization is called concentration polarization. Reduce the polarization method is to increase the electrode reaction area,08K8196 reducing the current density, increasing reaction temperature and to improve the catalytic activity of the electrode surface.