The Preparation And Electrochemical Performance Of Nanostructure Cathode Materials For Lithium-sulfur Batteries

As a new generation of lithium-sulfur secondary battery energy storage system,with green, wide range of sources, energy storage capacity advantages, is widespreadconcern in the community. But there are still some distance from the actual applicationof the use of commodity production and life.First of all, the elemental sulfur asconductive insulation, cannot be used alone as the anode material, secondly, theintermediate product in the process of charging and discharging polysulphide soluble inorganic electrolyte, shuttle effect, lead to the positive active material consumption,battery resistance increases, the cathode corrosion that make lithium battery capacityreduction, circulation performance degradation and so on destructive impact.This paper,by using activated carbon adsorption performance is good and the conductivity ofcarbon nanotubes good two kinds of carbon materials,design structure "ball","network"with high specific surface area of new carbon material by PTEF sealing cans and tubefurnace two ways mixing heat treatment，Elemental sulfur respectively mixed withsingle carbon materials and carbon materials for composite，and through scanningelectron microscopy (sem), thermogravimetric analysis and infrared analysis, XRDcharacterization methods of carbon/sulfur composite anode materials such asmorphology, sulfur content, sulfur content, surface functional groups andcharacterization of sulfur particles distribution， and carries on the charging anddischarging test at rate of0.1C.Respectively, the preparation of carbon nanotubes/sulfur composite (CNTs/S),activated carbon/sulfur composite (AC/S) and carbon nanotubes-activatedcarbon/sulfur composites (CNTs-AC/S) three sets of battery cathode material.Under thecondition of the preparation of carbon sulphur than same, through the hydrophiliccarbon nanotubes/sulfur, hydrophobic sulfur/carbon nanotube composite materials TGcurve contrast,hydrophilic carbon nanotube loaded sulfur content is higher,but thehydrophobic carbon nanotubes/sulfur discharge capacity is higher,which contained59.7%of the sulfur CNTs-B/S-5initial discharge capacity optimal for183.6mAh·g-1,during the test cycle,the carbon nanotube/sulfur material in the initialfew of cycles in the activation process is performed, a large capacity fluctuations;different sulfur containing activated carbon/sulfur composite charge and discharge cycle test,capacity loss after20cycles of about10%better than the carbonnanotube/sulfur composite at rate of0.1C,but the discharge capacity is relatively low;Mixed in different proportions to activated carbon and carbon nanotubes, carbon, sulfur,but at the same quality than (1:5) under the condition of the preparation of sample, getthe sulfur capacity of different carbon nanotubes-activated carbon/sulfur compositematerials，with the increase of the proportion of carbon nanotubes, sulphur load of thematerial to rise, However, the proportion of carbon nanotubes in CNTs-AC/S-20%minimum, its best performance cycle, sulfur loading was60.8%, the first dischargecapacity of133.6mAh·g-1,at rate of0.1C cycle after20times, loss to14%capacity.After six cycles, after the loop stability, the hydrophobic carbonnanotube/sulfur composite (CNTs-B/S-5), activated carbon/sulfur composite (AC/S-5)and carbon nanotubes-activated carbon/sulfur compound materials (CNTs-AC/S-20%)were compared,CNTs-AC/S-20%composite cycle performance is best, circulationafter20times, capacity loss was2%, the other two materials of capacity loss were12%and6%respectively.