Study Of Premature Capacity Loss On VRLA Batteries

With the aggravation of fossil energy crisis,electric vehicle has got extensive popularization. The VRLA batteries of electric vehicles are tending to development of long life and large capacity at present. However, the phenomenon of premature capacity loss (PCL) often takes place in the using of large capacity VRLA batteries, have influenced batteries'service life seriously. PCL on the large capacity VRLA batteries of electric vehicle which are produced by Lantian company were carried on research.Two kinds of type batteries which are life finished were anatomized. Density of sulfuric acid respectively in the top and lower parts of batteries'polar plate were tested, and positive active material (PAM) was tested by SEM,XRD,CV,IMP.We found reasons of PCL on 6DZM20 VRLA batteries and proposed the following solution to this problem.Citric acid,ammonium sulphate as the best matching of additive in the electrolyte were obtained by CV. And then added the compound additive in electrolyte to make experiment batteries, compared with blank batteries which were not added additive.The results showed that : additive batteries controlled the PCL evidently .Initial capacity and life were improved greatly . They have kept good charge maintenance at the room temperature and good charge acceptance at the low temperature, and fit to discharge in higher ratio. PAM of additive batteries was fine , symmetrical and no crystalline PbSO4 appearance by XRD,SEM tests ,which were opposite to blank batteries .The compound additives have improved batteries'comprehensive performance successfully. This text detailedly analysed the function mechanism of citric acid and ammonium sulphate.SiO2 powder were additived in the electrolyte to make gel-electrolyte batteries, which have obviously inhibited the sulfuric acid stratification, not only prevented PCL, made the battery obtain very good performance too. This text carried on detailed research to the function mechanism of gel- electrolyte too.