The use of red lead in the positive active material for pasted and tubular plates almost disappeared for several decades in China. Nowadays some battery manufacturers have used it again for reducing formation time and improving the deep discharge performance of batteries.Base on this background some physico-chemical characteristics of red lead and its influence on the battery production, performance and cost saving were introduced and discussed here.
1.Lead powder is stable, can be long-term stored without change.
When less than 2% free lead of red lead is used, the lead oxide powder almost does not undergo further oxidation, and the composition of the lead oxide powder is long-term stable and predictable.No complex analysis is required to verify the characteristics after transportation and storage.
2.Improve curing quality and improve battery performance.
Curing is one of the keys of battery plate quality.Plate bending, powder removing and life span are connected with curing.The main purpose of curing is to reduce the free lead of lead paste to a minimum of 5%.
3.Improve the quality of formation process.
Normally ,red lead is converted into β-PbO2 as the following equation
This reaction generates smaller crystals β-PbO2, enabling efficient transformation of the entire active substance.Therefore, the use of red lead can save time in the formation process and improve electric energy process of the plate.
4.Improve initial capacity of battery.
As we all know, the discharge capacity of the battery (positive plate) is derived from PbO2.A large number of studies have shown that PbO2 mainly has two types of crystal types, α-PbO2 and β-PbO2. They have the same chemical composition, but different crystal structures and different chemical activities.
The chemical activity can be expressed by its discharge characteristics. For the same amount of PbO2, the type β has a higher discharge capacity than the type α , and type β’s capacitance is 1.5-3 times than the type α’s .
The red lead will form those β-PbO2 crystals, so its use will improve the initial capacity, especially for stationary and industrial batteries.
5.Reproducibility and consistency.
When less than 2% free lead of red lead is used,the reproducibility of mixing paste and curing is greatly improved.
Usually in lead paste and the manufacturing process, some free lead has already begun to oxidation, and continued to oxidize during paste and curing. Due to too much lead free, every stage of metallic lead oxide quantity changes are also variable, of course, these plate assembly cells also variable.But once red lead is used, plate properties changed little in mixing paste and curing process, and thus improve the reproducibility and consistency have been improved, which provide the height of the plate performance consistency, it will be less waste and improve the quality of the battery.
6.The improved formation conditions are favorable for environmental protection
The red lead can not only shorten the formation time, reduce the power consumption,and produce less acid mist and gas.
Post time: Mar-31-2020