The battery is mainly composed of pole plate, partition plate, electrolyte and shell.
Pole plate
The pole plate is the core part of the battery and is mostly rectangular in shape. The factory first stamps the lead rolls into a mesh-like grid, and then coats the grid with the active substance commonly known as “lead paste”. The positive electrode is coated with lead dioxide and the negative electrode is coated with spongy pure lead. The charging and discharging of the battery relies on the chemical reaction between the active substance on the pole plate and the sulfuric acid in the electrolyte.
Usually a whole battery contains 6 plates, each plate group consists of several positive and negative plates, the number of negative plates is one more than positive plates, so that each positive plate is between two negative plates, which can make both sides discharge evenly.
Specially, the structure of the battery on the market is similar, only the formula of lead paste is the core secret of each battery manufacturer. The mesh shape of the grille is not always rectangular.
Spacer
The spacer is made of insulating material and is placed between the adjacent positive and negative plates to prevent short circuit when the positive and negative plates are in contact with each other. Plastic spacers are generally used in the market.
Electrolyte
The electrode plate is immersed in the electrolyte and reacts with the electrolyte chemically. The electrolyte is made of pure sulfuric acid mixed with pure distilled water in a certain ratio, but industrial sulfuric acid and tap water cannot be used as electrolyte, otherwise the electrode plate will be damaged.
Housing
The casing should meet the standard of shock resistance, acid resistance and heat resistance.
2. The working principle of the battery
After the battery is assembled and filled with sulfuric acid, it will rest for four or five days, and this process is called “formation”. So what kind of chemical reaction is going on inside the battery when it is formed?
First of all, look at the positive plate, the small amount of lead dioxide on the plate forms PB(OH)4 with the water in sulfuric acid, so there are tetravalent lead ions and hydroxide ions near the positive plate. PB4+ is concentrated around the plate, so the positive plate carries a positive potential.
Then look at the negative plate, a small amount of pure lead on the pole plate enters the electrolyte and forms divalent lead ions, while leaving two electrons on the pole plate, so the negative plate carries a negative charge.
At the end of the chemistry, when the state is neither charged nor discharged, the electric potential of the positive plate is higher than that of the negative plate.