以天然石墨和氧化石墨烯为原料，采用碳热还原法制备具有“核壳”结构的石墨烯／天然石墨复合材料。采用X射线衍射（XRD）、扫描电镜（SEM）等检测技术对合成材料的结构、形貌进行了表征。石墨烯包覆有利于天然石墨表面SEI膜的形成，同时，石墨烯壳层与导电剂构建的三网立体导电网络，加快了天然石墨粒子与集流体之间的电子交换速率，大大提高了复合材料的电导率，改善了其电化学性能。电化学性能测试表明，相比于天然石墨，石墨烯／天然石墨复合材料具有较高的比容量、优良的大倍率性能和优良的循环稳定性。如在0．1C下首次可逆充电比容量为4077．mAh／g，效率达到了998．8％、1C循环100次后容量保持率为991．8％。
We prepared a “core‐shell” structure of graphene/natural graphite composite from natural graphite and graphene oxide by carbothermal reduction .The synthesized material was characterized by means of X‐ray diffraction (XRD) ,scanning electron microscope(SEM ) and a variety of testing techniques .Graphene coating were favorable for the formation of SEI film on the surface of natural graphite ,at the same time ,three solid conductive network has been successfully fabricated by the graphene shell and conductive agent in the electrode to accelerate the electronic exchange rate of between natural graphite particles and current collector ,greatly in‐crease the conductivity of composite materials ,and improve its electrochemical properties .The electrochemical performance testing results showed that graphene/natural graphene composite exhibited high specific capacity , superior rate performance and excellent cycle stability .Such as its initial charge capacity is 407 7. mAh/g with the coulombic efficiency of 99 8.8% at the rate of 0 1. C and capacity retention ratio after 100 cycles is 99 1.8% at the rate of 1 C .
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