Research On Modified Activated Carbon For Pb-C Ultra-battery And Its Electrochemical And Battery Performance

Pb-C ultra-battery is a kind of new energy storage device which is incorporated with lead-acid battery and super-capacitor in the form of internal combination which has the advantages of the lead-acid battery and super-capacitor.So it is very suitable for hybrid electric vehicle for its superior performance of high-rate charging-discharging performance.However,the introduction of carbon materials brought about the inconsistency of the potential of electrochemical reaction of lead and carbon,which led to the acceleration of hydrogen evolution at the end of charging.Therefore,the research of carbon materials which possessed high specific capacity and high over-potential of hydrogen evolution in sulfuric acid electrolyte is the key of ultra-battery development.the following three aspects has been studied in the present thesis.The commercial AC was used as the raw material and the activated carbon with high specific capacity was obtained by the technique of reactivation,together with variation of the type of activator,the concentration of the activator and the activation temperature.The results of CV curves and chrono-amperometric detection with the modified AC showed that the specific capacitance of modified activated carbon(AC-M)was 331 F/g.AC-M was prepared under the condition of 65%H3PO4 and 800 ?.The results of SEM detection showed that the proportion of mesopore of AC-M has increased.Electrochemical tests show that the effect of inhibition of hydrogen evolution is better when AC was modified by In2O3 and Bi2O3.Finally,high rate discharge performance of Pb-C batteries was excellent when AC-M was applied to the negative plates.PbS04/AC was prepared by the process of adsorption of Pb2+ and in situ deposition of PbSO4 in the pores of activated carbon.The phase composition and microstructure of PbSO4/AC material was characterized by XRD,SEM and EDS analysis.The results showed that PbS04 crystals with the size of being less than 200nm were dispersed uniformly on the surface of the activated carbon particles.The mass fraction of lead element in the PbSO4/AC sample was 26.43%.PbSO4/AC was used to prepare the electrodes and the electrochemical performance were detected in H2SO4 solution.The results showed that PbSO4/AC has high over-potential of the hydrogen evolution and a certain degree of oxidation-reduction current can be provided.The loss of non-faradic specific capacity was relatively small.PbS04/AC was used to prepare the negative plate by the traditional technology of paste preparation in which the ratio of PbSO4/AC with leady oxide being 5%(wt).The cycle life of the battery prepared was 3 to 4 times higher than traditional lead-acid battery under the condition of 60%SOC and the time of both high rate discharging and charging being 60s.Pb(PbO)/AC was prepared by the process of adsorption of Pb2+,deposition of PbO and further reductive decomposition in the pores of activated carbon.The phase composition and microstructure of Pb(PbO)/AC material was characterized by XRD,SEM and EDS analysis.The results showed that Pb and PbO nano-crystals were dispersed uniformly on the surface of the activated carbon particles.Pb(PbO)/AC was used to prepare the electrode and the electrochemical performance were detected in H2SO4 solution.The results showed that Pb(PbO)/AC has high over-potential of the hydrogen evolution and a certain degree of oxidation-reduction current can be provided.The loss of non-faradic specific capacitance was smaller.The present Pb(PbO)/AC was used to prepare the negative plate by the traditional technology of paste preparation in which the ratio of Pb(PbO)/AC with leady oxide being 5%(wt).The cycle life of the battery prepared was 4 to 5 times higher than traditional lead-acid battery under the condition of 60%SOC and the time of both high rate discharging and charging being 60s.