Modification Of Mesocarbon Microbeads With Graphene And Their Applications In Lithium-Ion Battery Anode

With the widespread application of portable electronic devices and quick development of electric vehicles,the high energy density and high power density energy storage devices,especially the lithium ion batteries?LIBs?are highly demanded.Owing to the unique morphology and excellent properties of graphene and reduced graphene oxide?rGO?,they have been widely used as anode or the additives to improve the electrochemical performance of conventional anode materials for LIBs.In this work,rGO was designed to modify the commercial mesocarbon microbeads?MCMB?,one of conventional anode material for LIBs,—to improve its electrochemical properties.However,due to the poor hydrophilcity of MCMB,it is difficult to mix with graphene oxide?GO?uniformly in aqueous solution.In order to solve this problem,surface-activated treatment was used first to modify the hydrophilcity of MCMB by increasing the surface oxygenic functional groups,which was conductive to form a well-coated composite between MCMB and graphene oxide.Additionally,the GO was thermally reduced into rGO,and finally the continuous rGO conductive network was formed on the surface of MCMB.Thus,electron conductivity and lithium ion diffusion efficiency of MCMB were improved,which are beneficial to their electrochemical performances as anode for LIBs.The detailed research contents and results are:?1?The MCMB was treated by oxygen plasma under different conditions.The as-obtained MCMB was mixed with GO sheets in water under vigorous stirring to get the composites of MCMB/GO.After thermochemical sulfate reduction,MCMB/rGO was obtained finally.The morphology and surface structure of the as-prepared composite were analyzed using FE-SEM,Raman spectroscopy,and contact angle analysis.It was illustrated that the rGO was coated uniformly on the MCMB.The composite shows pronounced electrochemical performance as anode for LIBs,for instance,the specific capacity can reach 180 mA h g^-1 at 1 A g^-1.?2?The MCMB was treated by hydrothermal method using glucose.Glucose-modified MCMB and rGO were used as raw materials to prepare composites of MCMB/rGO.The surface morphology and electrochemical properties of the composite were investigated.The results show that the surface of MCMB has a uniformly coating layer that is rGO film.The electrochemical measurements showed that the composite displays the better specific capacity,higher rate performance and stable cycle stability as anode for LIBs,for example,the specific capacity of the composite reaches about 340 mA h g^-1 when the current density is 0.1 A g^-1.The research results envisage that a well-coated composite between MCMB and graphene was gained through modifying the MCMB using surface-activated treatment.The electrochemical properties of the anode materials of lithium ion batteries were improved,which hold great potentials for practical applications.