Electrochemical Behavior Of Carbon In The Negative Electrode For Pb-C Batteries And Its Performance For Energy Storage Application

Lead-carbon battery is a new-developed battery that combines the benefits of lead-acid battery and supercapacitor.It has the advantage of high energy density,and also has the characteristics of supercapacitor,which integrates super-long cycle life,high power and good charging acceptance.Lead-carbon battery can be used in all kinds of energy storage systems,especially for cycling under partial-state-ofcharge.However,the effect and mechanism of carbon materials on the performance of lead-carbon batteries are still unclear.The specific surface area of carbon materials and negative mass were measured by Nitrogen aspiration and desorption,the micro-morphology of carbon materials and negative mass was observed by scanning electron microscopy(SEM),the particle size distribution of carbon materials was measured by particle size analyzer,and the crystal structure and phase composition were analyzed by X-ray diffraction spectrometer(XRD).The effects of carbon materials on the microstructure and electrochemical properties of the negative electrode were studied.Suitable carbon materials for lead-carbon battery were screened out,and lead-carbon products with high performances are developed.The micro-structure of activated carbon,carbon black,carbon fiber(CF),carbon nanotubes(CNT),graphene(GN)was analyzed,and the effects of the structure of five kinds of carbon on the performance of the lead-carbon electrode were compared.It is discovered that activated carbon,carbon black and graphite can improve the charging acceptance of batteries and prevent irreversible sulfation on the surface of negative electrodes,thus improving the cycle life of high rate partial charge state(HRPSOC).The relationship between the types and contents of impurity in carbon materials and the performance of electrodes was studied.It was found that in a certain range,there was no obvious positive relationship between impurity contents and hydrogen evolution.Through the comparative test of simulated batteries,the mechanism of action of carbon materials on the negative electrode of lead-carbon batteries was studied.It was demonstrated that the effect of carbon materials on the microstructure and composition of the negative electrode was not entirely due to the high specific surface contribution of carbon materials,but was closely related to the surface area and oil absorption number.Different distribution versions of carbon materials through the negative plate are designed.The specific surface area,porosity and pore size of the negative mass are characterized,and the electrochemical performance of battery are tested.It is discovered that high carbon loading at the surface of negative electrode has more beneficial effect on charge acceptance,lower temperature discharge and high-rate partial-state-of-charge cycling performance.But high carbon loading at the surface of negative electrode results in more gas evolution.The requirements for different energy storage scenarios such as peak shaving and frequency modulation are different.Therefore,two kinds of lead-carbon prototype cells are designed with different negative and positive plate thickness.The electrochemical performance under these two energy storage conditions is investigated.