Preparation Of Lead-carbon Composites And Their Applications In Lead-acid Batteries

Lead acid batteries account for nearly 50% of the energy storage system market due to their excellent safety performance,low cost,good recoverability,structural stability and easy maintenance.However,in view of the irreversible sulfuration caused by negative electrode discharge products,lead acid batteries have disadvantages such as low energy density and short cycle life,which also hinder their development in the new energy market.With the development of graphene materials,lead carbon batteries can be formed by adding carbon materials to the negative electrode of lead acid batteries to solve the above problems.However,the addition of carbon material will lead to serious hydrogen evolution in the negative electrode.In addition,because of the large discrepancy between proportion of carbon material and negative active substance the two will become incompatible,with a poor binding force,leading the negative active substance to fall off,battery failure and other problems.Therefore,the above problems should be solved by modifying and modifying graphene to prepare graphenebased composites.In this thesis,three-dimensional graphene/lead composites were prepared by two methods.As an additive for the anode of lead-acid battery,it not only improves the utilization rate of the anode active substance,enhances the multiplier performance of the battery,but also improves the hydrogen evolution problem caused by the addition of carbon material and the separation of the cathode active substance.Specific research contents are as follows:(1)Three-dimensional graphene/lead(SCG-Pb)composites are prepared by electrodeposition method.After acidification treatment,acidic functional groups carried by the SCG surface are made.In the process of ultrasonic dispersion,Pb2+ in the solution is captured by negatively charged oxygen-containing functional groups under the action of the interaction between charges.The charge provided by the external circuit causes Pb2+to be reduced at the in-situ point and grow into lead nanoparticles.Compared with the control group,the initial discharge capacity of the battery with SCG-Pb is 23.16% higher(183.95 m Ah g-1),and the capacity retention is 2.6 times higher(80 m Ah g-1)after 1C rate of 120 cycles.This work provides a feasible strategy to improve the performance of lead-acid batteries by modifying graphene.(2)SCG@PbO material is prepared by solvothermal pyrolysis method,which consisted of three-dimensional graphite substrate and uniformly distributed nanometer PbO particles on its carbon atom skeleton structure.Due to the modification of PbO particles,the SCG@PbO material can be uniformly distributed in the negative material of lead-acid battery.It not only improves the utilization rate of active substance of negative plate,but also effectively refines the lead sulfate particles,thus improving the performance of lead-acid battery.In addition,SCG@PbO material with high hydrogen evolution potential can effectively alleviate the hydrogen evolution problem caused by carbon materials.The cycle life of the battery at 2 C with high rate partial state of charge(HRPSo C)is 31398 cycles,which is 731% higher than that of the control battery.The water loss due to hydrogen evolution is reduced by 60% compared to SCG batteries.This work provides a new feasible idea for large-scale preparation of threedimensional graphene to improve the performance of lead-acid batteries.