| With the rapid development of electronic products,people have higher and higher requirements for mobile energy storage devices.However,currently commercial lithium ion batteries have been difficult to meet the needs of daily life.Therefore,efficient energy storage device has become a research hot spot.Due to the high theoretical specific capacity of sulfur,abundant resources,low prices,and no pollution to the environment,research on lithium-sulfur batteries has become a hot field in current high-efficiency energy storage devices.Despite these advantages,the positive electrode material of sulfur as lithium-sulfur batteries still faces some difficulties in actual charging and discharging:（1）Poor conductivity of sulfur and Li2S generated during charging and discharging;（2）The lithium sulfide generated by sulfur in the early charge and discharge is easily dissolved in the organic electrolyte,resulting in the shuttle effect and the loss of active substances.（3）In the process of charging and discharging,sulfur reacts with lithium repeatedly,resulting in the expansion of electrode volume,resulting in battery damage.In this paper,three-dimensional graphene was compounded with elemental sulfur to improve its conductivity and inhibit the shuttle effect of polysulfide by adsorption.First,the modified Hummers method is used to obtain brown graphene oxide.A three-dimensional reduces graphene oxide/nano-sulfur（3d RGO-S）positive composites is prepared by high-temperature thermal diffusion method of nano-sulfur into the three-dimensional space of graphene,which are synthesized by hydrazine hydrate reduction of graphene oxide.The microscopic structure and morphology of the composites are characterized by XRD,SEM and TEM,while the electrochemical properties are studied by galvanostatic charge-discharge measurements and cyclic voltammetry（CV）electrochemical impedance spectroscopy（EIS）.The results show that graphene has a three-dimensional structure,which can effectively improve the utilization of the active substance sulfur,and 3d RGO has a uniform S coating on 3d RGO.The 3d RGO-S composite electrode of loading sulphur 66%proportion and adding active carbon of the battery manifestes a high initial capacity（1150 mAh/g,0.1 C）and excellent capacity stability after 600 cycles,but the discharge capacity could retain 700 mAh/g. |
