About the batteries

In cell chemical chemical energy directly into electricity by the battery is carried out within the spontaneous oxidation, reduction and other chemical reactions the result of the reaction was conducted in two electrodes. Negative active material of the more negative potential and an agent of the stable reduction in the composition of electrolytes, such as zinc, cadmium, lead active metals and hydrogen or hydrocarbons. Positive active material for a more positive potential on the composition of the electrolyte of a stable oxidizing agent as manganese dioxide, lead dioxide, nickel oxide and other metal oxides, oxygen or the air, halogens and their salts, oxygen-containing acid and its salts etc.. Electrolyte is a good ionic conductivity materials such as acids, alkalis, saline, organic or inorganic non-aqueous solutions, molten salts or solid electrolytes. When the external circuit disconnected, although there is potential difference between the two poles (open circuit voltage) but there is no current stored in batteries are not converted to chemical energy into electrical energy. When the external circuit is closed, the two electrodes under the effect of potential difference there is current flowing through the external circuit. The same time, the battery inside the electrolyte are not due to free electrons, charge transfer must be accompanied by two poles of active material and electrolyte interface, the reactions of oxidation or reduction, and reagents and reaction products of mass transfer. Charge transfer in the electrolyte, but also by the migration of ions to complete. Therefore, the battery in the normal transfer process and mass transfer is to ensure that the conditions necessary for normal production of electricity. When charging, the battery inside the transmitter power and direction of mass transfer and discharge exactly the opposite reaction of the electrode must be reversible to ensure the opposite direction to the mass transfer and mass of normal electrical processes. Therefore, the electrode reaction is reversible, a necessary condition for the batteries. Reaction of the Gibbs free energy (coke) F is the Faraday constant = 96,500 basis = 26.8 ampere-hour n the equivalent number of the cellular response. It is the reaction of the battery and the emf of the battery between the basic thermodynamic relations, but also calculate the energy conversion efficiency of cells of the basic thermodynamic equation. Indeed, when current flows through the electrodes, the electrode potential must deviate from the equilibrium thermodynamic potential of the electrode, a phenomenon known as polarization. Current density (electrode surface unit adopted by the current), more polarization worse. Polarization is caused by the energy loss of the battery of important reasons. Polarization for three reasons: ① from the cells caused by different parts of the polarization resistance is called Ohm polarization; ② electrode – interface layer caused by electrolyte charge transfer blocked the process of polarization is Name polarization activation; ③ electrode – electrolyte interface layer caused by the slow mass transfer of polarization is called concentration polarization. Reduce the method of polarization is to increase the reaction zone to the electrode, which reduces the current density, increasing reaction temperature and improve the catalytic activity of the electrode surface.