Effect Of Polyaniline And Thorn-like Lead Sulfate On The Performance Of Lead Sulfate Negative Electrode

Because of their mature manufacturing technology,low cost and complete recovery system,lead-acid batteries have played an important role in the hybrid electric vehicles,uninterrupted power supply and energy storage systems.In order to satisfy the increasing demand of industrial development,the electrochemical performance and consistency of lead-acid batteries,especially the cycle life,needs to be further improved.In addition,during the deep charge-discharge process,lead sulfate（PbSO₄）would gradually accumulate on the surface of negative electrode,forming an irreversible PbSO₄ layer（sulfation of negative electrode）,which greatly limits the cycle life of lead-acid batteries.Therefore,it is necessary to carry out the research on inhibiting the sulfation of negative electrode and prolonging the cycle life of lead-acid batteries.In this thesis,the negative electrode additives and materials were investigated.The major contents and research results are as follows:1.Polyaniline materials were synthesized by chemical method,interface method and template method,and used as negative electrode additives.Polyaniline has good electrical conductivity and pseudo capacitance,which can improve the charge-discharge performance of negative electrode.The study found that the polyaniline prepared by oxidation method and template method had higher specific capacitance,and the polyaniline prepared by interface method（PANI-CCl₄）had better hydrogen evolution inhibition performance.In the charge-discharge process,polyaniline can be used as a current buffer and improve the rate performance of the battery.During the charging process,the hydrogen precipitation can be inhibited and the reduction of PbSO₄can be promoted.When the specific discharge capacity reached 80%of the maximum specific discharge capacity,the cycle life of the PANI-CCl₄ electrode was increased by 59%compared with that of the electrode without the use of polyaniline.2.Polyaniline/acetylene black（PANI/AB）composites were prepared and used as negative electrode additives.PANI/AB composite material has high conductivity,specific capacitance and good hydrogen evolution inhibition performance.It can bear part of the charge-discharge current and inhibit hydrogen evolution to relieve the accumulation of PbSO₄ layer.It was found that when the concentration of aniline solution was 0.025 mol L^-1,PANI/AB-0.025 had the best electrochemical performance.At a current density of 100 m A g^-1 and 100%depth of discharge（DOD）,the maximum specific discharge capacities of the AB electrode（electrodes with acetylene black added only）and PANI/AB-0.025 electrode were 102.62 and 112.25 m Ah g^-1,respectively.After 800 cycles,the specific discharge capacities of the AB electrode and PANI/AB-0.025 electrode were 74.3 and 105.6 m Ah g^-1,which were maintained at 72%and94%of the maximum,respectively.PANI/AB composite is a promising anode additive because of its simple synthesis method,which can effectively improve the discharge capacity and cycle stability of lead-acid batteries.3.Thorn-like and dendrite PbSO₄ with a high aspect ratio were prepared and used as negative electrode materials.Compared with the near spherical PbSO₄,thorn-like and dendrite PbSO₄ can significantly change the pore structure of the negative active material and provide good ion transport channels.During charge-discharge process,it can reduce the concentration polarization and improve the specific discharge capacity and rate performance of the battery.At a current density of 100 m A g^-1 and 100%DOD,the specific discharge capacities of all the thorn-like and dendrite PbSO₄electrode were>110 m Ah g^-1.After 1200 cycles,the specific discharge capacities were>80 m Ah g^-1.When the specific discharge capacity reached 80%of the maximum,the cycle life of thorn-like and dendrite PbSO₄ batteries was 64%longer than that of the nearly spherical PbSO₄ battery.Owing to their facile preparation and excellent cycling performance,thorn-like and dendrite PbSO₄ particles are promising materials for the negative electrode of lead-acid batteries.