Structure of battery
The plate is the core part of the battery. In the process of charging and discharging, the conversion of electric energy and chemical energy depends on the chemical reaction between the active material on the plate and sulfuric acid in the electrolyte.
The electrode plate is composed of grid and active material. The thickness of positive plate is 2.2mm, and that of negative plate is 1.8mm.
The grid frame is made of lead antimony alloy. The purpose of antimony support is to improve the mechanical strength and casting performance, but antimony has side effects, which will accelerate the precipitation of hydrogen and accelerate the consumption of electrolyte, resulting in self discharge and grid corrosion.
The active substance is the working substance on the plate. The active material on the positive plate is lead dioxide (PbO2), which is dark brown; the active material on the negative plate is spongy pure lead (PB), which is dark gray.
The electromotive force of about 2.1 can be obtained by immersing the positive and negative plates in the electrolyte. In order to increase the capacity of the battery, several positive and negative plates can be connected in parallel respectively, and the positive and negative plates can be welded into a group of positive and negative plates with horizontal plates. The positive and negative plates are interlaced and inlaid with each other, and the separator is inserted in the middle and then installed into the single cell of the battery to form a single cell battery. In each cell, the negative plate is always more than the positive plate. Because the active material on the positive plate is loose, and the chemical reaction at the positive plate is more violent than that on the negative plate, the volume of the active material changes greatly before and after the reaction, so the positive plate is sandwiched between the negative plates, which can make the discharge on both sides uniform, so as to reduce the warpage of the positive plate and the shedding of the active material.
The function of the separator is to make the positive and negative plates as close as possible without short circuit, reduce the volume of the battery, and prevent the deformation of the plates and the shedding of active substances.
The separator is made of microporous plastic, which is porous to facilitate electrolyte penetration, and has good acid resistance and oxidation resistance. The area of the separator is slightly larger than that of the electrode plate, and one side is provided with longitudinal grooves. Considering that the chemical reaction of the positive plate is violent in the process of charging and discharging, and the electrolyte flux is large, the side of the separator with groove should face the positive plate, and the groove should be perpendicular to the bottom of the shell. The groove can not only make the electrolyte flow up and down, but also make the bubbles rise along the groove, and also make the falling active substances sink along the groove.
The function of electrolyte is to form ionization, promote the dissolution of the active substance of electrode plate, and produce reversible electrochemical reaction. It is made up of chemically pure sulfuric acid with relative density of 1.84 and distilled water in a certain proportion. The minimum air temperature (31G / cm2-1.24) should be selected according to the local requirements.
The purity of electrolyte is an important factor affecting the electrical performance and service life of battery. Therefore, hgb1008-59 grade II special sulfuric acid and distilled water should be used. Industrial sulfuric acid and general water containing harmful impurities such as iron and copper increase self discharge and plate damage, so they can not be used in batteries.
4. Battery shell
The shell is used to hold the electrolyte and plate group, so that the lead-acid battery forms a whole. The shell materials are hard rubber and plastic. The shell is an integral structure. The inner shell is divided into three or six unconnected single cells by the partition wall, and the bottom is made with ribs to support the plate group. The gap between the ribs may accumulate the active substances from the plates to avoid the short circuit between the positive and negative plates. There is a filling hole in the middle of the cover of each cell, which can be used to check the liquid level and measure the relative density of electrolyte. The filling hole is usually tightened with the filling hole. The ventilation in the center of the filling hole cover shall be kept smooth. The gas released from the chemical reaction of the battery can escape at any time. A protective plate is installed on the upper part of the plate group to prevent the upper part of the plate from being damaged when measuring the relative density and liquid level of electrolyte or adding electrolyte. The gap between the small cover and the shell is sealed with sealing glue, which can ensure no overflow at 65 ℃ and no crack at - 30 ℃.
The plastic shell adopts the integral cover, and the heat sealing method is adopted between the cover and the shell.
5. Joint clause
The function of the connecting strip is to connect the single cells in series to improve the terminal voltage of the whole lead-acid battery. The ordinary battery connection is also made of lead antimony alloy. The connection of the hard rubber shell battery is located above the small cover of the battery. The plastic shell battery adopts the wall through type connection.
There are three kinds of terminals, i.e. tapered, L-shaped and side hole shaped, welded on the horizontal plate of the head and tail plate group of ordinary lead-acid battery. For the convenience of distinguishing, the positive terminal is marked with "+" or "P" on or next to it, and the negative terminal is marked with "-" or "n". Some battery terminals are painted red.