What is the cause of positive plate corrosion of Shanterups battery?The dense lead dioxide molecule volume produced by grid corrosion is 1.4 times that of lead atom. Because the volume of alloy grid differs greatly from the volume of corrosion products transformed from alloy grid, tension is exerted on the grid, resulting in the deformation of the grid. The thicker the corrosion film is, the greater the tension applied on the grid, the more serious the deformation of the grid is, which aggravates the influence of active substances and corrosion products. The bonding ability of alloy grids results in the loss of active substances, which seriously affects the output capacity of batteries. This is the common reason for the capacity decline of lead-acid batteries in operation. Positive electrode corrosion can not be eliminated by lead-acid battery technology, because the alloy composition of grid is different from that of active material, and the active material is directly attached to the grid. Both of them are directly contacted and immersed in sulfuric acid electrolyte. Each of them establishes different balanced electrode potentials with the electrolyte, and the difference of balanced potential constitutes short-circuit micro-battery, which causes the corrosion of the positive electrode inevitably. For this reason, the positive grid thickness is thicker than the negative grid thickness in the production process of Shanterups battery to compensate for the positive corrosion.
The corrosion and fracture of positive plate of Shante UPS battery are mainly caused by the following reasons:
The bending of the plate mostly occurs in the positive plate, while the negative plate seldom occurs. Some of the bending of the negative plate is caused by the bending of the positive plate, even forcing the negative plate to bend.
The fracture of the plate often occurs during the service life. Because of the corrosion of the grid, the strength of the plate decreases, resulting in the fracture of the plate, especially the performance of the positive grid is more serious. The main reasons for the bending of the plate are as follows:
(1) In the process of manufacture, the active material of the plate is formed or pasted unevenly, and the positive plate is corroded, that is, the process of forming oxide film. Therefore, the electrochemical action of each part of the plate is not uniform during charging and discharging, which causes the volume expansion and contraction of the active material on the plate to be inconsistent and causes bending, and the linear size of the grid to be increased. Deformation or expansion of grids may even cause cracking.
(2) During the charging and discharging process of lead-acid batteries, the active substances of the plates gradually fall off due to damage. This phenomenon mainly occurs in the early stage of cyclic charging and discharging. The main feature is that there are precipitates in the electrolyte and the capacity of the batteries decreases. Abscission of active substances is a normal phenomenon when the service life of batteries is close to termination.
(3) Overcharging or over discharging, when charging, the positive grid is in the condition of anodic polarization, which increases the expansion and contraction of the inner active material, and the recovery process is inconsistent, resulting in the bending of the plate. Frequent over charging is the main cause of corrosion and fracture of the positive plate.
(4) When discharging at high current or high temperature, the reactions of active substances on the plates are more intense, which can easily lead to uneven chemical reactions and lead to plate bending.
(5) There are some problems in the manufacturing process of grid alloy. The battery contains impurities. When it causes local action, only a small part of the active material becomes lead sulfate, which results in inconsistent volume changes of the active material of the whole plate and causes bending.
(6) The high density and temperature of electrolyte aggravate the oxidation corrosion of positive plate. In the electrolyte of lead-acid batteries, acids or other organic salts which corrode the positive grid will gradually corrode the positive grid. These acids and salts harmful to the positive grid may come from sulfuric acid, distilled water, or may be leached from partitions or other components. Therefore, in the charge-discharge cycle, the plate or positive grid is constantly corroded.