Application
The use of barium sulfate in lead storage batteries
Barium sulfate is used as an additive in battery negative lead paste in the production process of batteries. It has lattice parameters similar to lead sulfate and is an isomorphous substance. The main function of adding barium sulfate is to act as the crystallization center of lead sulfate during discharge. Since lead sulfate can be crystallized out on isomorphous barium sulfate, there is no need to form lead sulfate crystal nuclei, so that the supersaturation necessary to form the crystal nucleus will not occur. In addition, the presence of barium sulfate makes the discharge product lead sulfate not precipitate on lead, but on barium sulfate, so that the active material lead will not be covered by the lead sulfate passivation layer, and the barium sulfate can delay passivation. During the charging process, barium sulfate also prevents the specific surface area of lead from shrinking.
At present, there are two kinds of ultra-fine precipitated barium sulfate commonly used in domestic battery factories. One is precipitated barium sulfate containing modifiers, such as modified ultra-fine barium sulfate for batteries, and the other is precipitated barium sulfate without any modifier. We believe that the addition of modified barium sulfate is not suitable for storage batteries, according to the following:
The median diameter of ultra-fine precipitated barium sulfate particles is generally around 1.5 micro meter. In the natural state, the powder particles are prone to agglomeration when no modifier is added, the surface area is obviously increased, and the morphology is irregular. In order to better use barium sulfate in the coating, ink, rubber, plastic, paper, glass and fragrance industries, manufacturers add modifiers and surfactants during the precipitation reaction stage of barium sulfate to achieve the purpose of modification. The surface of barium sulfate that has not been modified is hydrophilic, has good dispersibility in water, and settles after standing. The modified ultrafine barium sulfate is suspended in water due to its strong hydrophobicity. On the other hand, the volume of the particles is increased, and the apparent density of the barium sulfate particles is reduced. However, if this kind of barium sulfate with modifier is placed in an acidic medium, it will behave like barium sulfate without modifier, and it will settle. We believe that the purer the material used to manufacture the battery, the better. The addition of barium sulfate to the modifier is a harmful impurity for the battery. We should have a clear understanding.