Study On The Application Of Graphene-based Carbons In The Lead-carbon Batteries

Because of energy stringency and environmental crisis,more and more differenttypes of hybrid electric vehicles(HEVs),which are environment-friendly andresource-saving,emerged.Due to advantages of low cost and long cycling life underhigh-rate part-state-of-charge(HRPSoC) conditions,lead-carbon batteries areconsidered as a promising power source for HEVs.The carbon materials added into thenegative electrode of lead-carbon batteries can serve as a “buffer” to inhibit negativeplate sulfation.In this paper, the influences of the six kinds of graphene materials on the cyclingperformance of batteries have been studied firstly. The expanded graphene materials(AGS) and graphene nanosheets(BGS) were added into negative plates of lead-carbonbatteries, and the properties of the batteries were measured. The experimental resultsindicats that all of these six kinds of graphene materials benefit the batteryperformances to different extents. The results show that the best cycling performancewas achieved with a cycle number of12557when0.2%AGS-1was used, while thedirect addition of BGS in the negative plate Pb paste achieved a large cycle number of12194.Considering the good influence of graphene materials on the battery properties,on the basis of the researches on simple addition of graphenes, the combinations ofgraphene and activated carbon or mesoporous carbon were investigated as carbonadditives in lead-carbon batteries, including the mixture additives of graphene andactivated carbon, graphene-coated activated carbon(AC@GNS) and graphene-coatedmesoporous carbon(CMK-3@GNS). The results show that the batteries added withthese two kinds of carbon additive combinations exhibited better cycling performanceand charge acceptance capability compared with the conventional lead-acid batteries.The cycle number of the lead-carbon battery with mixture additive of0.2%AC-1and0.2%AGS-4reached6230, while the battery with0.5%CMK-3@GNS cycled5986times and the battery with0.5%AC@GNS cycled7360times.The evolution of negative electrode potentials and impedance behaviors of thebatteries with the efficient and inefficient carbon additives with HRPSoC cycling wasexamined. And the negative electrode potentials and impedance behaviors were furtherdisintegrated into components related to different basic electrode processes to analyseand propose the mechanism of the carbons added into lead-carbon batteries. Theanalyses show that, firstly, the addition of the efficient carbon additive can maintainthe electrochemical activity of the negative plate to ensure the redox reaction between PbSO4and Pb. Secondly, the accumulation of big and stiff PbSO4crystals is inhibited,while the formation of small and reactive PbSO4crystals is promoted. At the sametime, the deteriotation of diffusion status is retarded. Therefore, the cyclingperformance is enhanced.