Research On High Temperature Curing Technique Of Positive Plates For Lead-acid Batteries

In recent years,with the rapid development of communication and new-energy industry,users of lead-acid batteries put forward higher requirements about cycle life.The main reasons for failure of cycle life are softening and shedding of positive active materials,which is related to the technology of plates curing.Fundamental research shows that the tetrabasic lead sulfate(4BS,4Pb O·Pb SO4)will be formed in the plate cured at high temperature and which can significantly improve the cycle life of lead acid batteries.In this paper,the plates prepared under different curing temperature(80 ??100 ??120 ?)and different curing time(2 h?4 h?6 h?8 h?10 h)were investigated.The composition and morphology of various plates were characterized by X-ray diffraction(XRD)and scanning electron microscope(SEM).Meanwhile,the effects of some parameters such as specific surface area on the discharge performance and cycle life of lead-acid batteries were investigated.The influence of curing conditions on the plates shows that when the curing temperature reaches above 100 ?,the phenomenon of “bulging” occurs on the surface of the plate,and the appearance and strength of the plate are too poor to meet the requirement.The results also indicate that curing temperature and curing time are important factors in the formation of 4BS.The higher curing temperature leads to the more rapid formation of 4BS,and prolonging curing time will increase the content and grain size of 4BS in a certain range.When cured at high temperature,the particle size distribution of the 4BS is wide.Increasing curing temperature can accelerate the formation rate of corrosion layer,and is favorable to improve the bonding degree of the active materials with the grid.The optimum curing condition of this paper is cured at 80 ? for 6 h.But the initial capacity of batteries assembled by plates purely cured at high temperature is lower than the normal ones cured at room temperature,and the homogeneity is poor.By investigating the plates prepared by adding the “4BS seed crystal”(1%)in lead paste before cured at high temperature,it is found that the introduction of “4BS seed crystal”can decrease the grain size of 4BS(from 70 ?m to 20 ?m)and improve the uniformity of crystal and the specific surface area of plates;It will not alter the content of 4BS in the plates,but can improve initial capacitance of batteries and the homogeneity of capacity.The results show that the total cycle life of batteries made of these as-obtained plates is improved by 30% than the batteries cured at room temperature.