Investigation Of The Effect Of Electrolyte Additives On Battery Performance Of Valve-regulated Lead-acid Batteries

Due to its advantages such as low cost and good electrochemical performance,lead-acid batteries have been widely used as power sources on automobiles,electric vehicles,communications and other industrial applications.Nowadays,the development of the lead acid battery is mainly relevant to the technical improvement in the battery.This work is to study the influences of electrolyte additives on the performance of lead acid battery,which will provide methods to prevent the formation of lead dendrites in AGM separator and inhibit the corrosion of the negative plate strap,reduce the cost of battery manufacture,through using the influence of sulfate additives on the battery.The conclusions are drawn as following:(1)AAS was used to analyze the influences of sulfate additives on the dissolution of PbSO4.The studies are as follows:high temperature and low acidity will accelerate the dissolution of PbSO4.When Na2SO4 as electrolyte additive added to the electrolyte,the common-ion effect will largely decrease the dissolution of PbSO4.The concentration of Pb2+ ions is the lowest in the concentration range of 0.2-0.5%Na2SO4.The dissolution of PbSO4 in the high concentration of K2SO4 is lower than in the same concentration of Na2SO4.So the high concentration of K2SO4 can be used as an inhibitor to prevent the formation of the PbSO4 and lead dendrite.(2)The over-discharge way employed to simulate the cell short circuit caused by lead dendrites generated in the practical application.The results indicate that with the over-discharge going,the dissolution of PbSO4 increases,the dissolved Pb2+ ions can diffuse into the AGM separator.The PbSO4 crystals grow from tiny particles to large crystals.The lead dendrite is transformed from PbSO4 crystals,first,the lead dendrite grows into texture structure,then the lead dendrite grows into many platelets and micro-crystal,and becomes continuous and dendritic crystal structures ultimately.(3)The impacts of different sulfate additives on battery performance weremeasured.The conclusions are as follows:the VRLA battery with 0.5%Na2SO4 additive has a good discharge capacity at 0.5 C?1C?3 C rate and at-15 ? low temperature,and its performance is better than the VRLA battery with 1.5%Na2SO4 additive which is applied in the actual production currently.The decreases of the Na2SO4 concentration can reduce the risk of dendrite short circuit in VRLA batteries,improve battery performance and reduce the cost of manufacture.(4)The effect of electrochemical behavior on the Pb electrodes has been studied by means of CV and EIS methods in H2SO4 electrolyte with different sulfate additives.The results show that the addition of the Na2SO4 will down the anode peak current of Pb electrode,which is due to fact that the formation of a relatively dense PbSO4 film on the Pb electrode surface and it can further prevent corroison of electrode.EIS methods indicate that Na2SO4 additive increases the dense anodic films and polarization resistance on Pb electrode.The impedance on low frequency in 2%K2SO4 is larger than others in low concentration of Na2SO4.The addition of K2SO4 can inhibit the corrosion of the negative plate strap.