Applitd Research Of The Carbon Material Contained Ultrahigh Graphitization In Lithium-sulfur Batteries

Lithium-sulfur batteries were regarded as one of the most promising candidates due to its high theoretical capacity(1675 mAhg^-1)and natural abundance of sulfur.However,three practical problems in the cathode including?1?notorious shuttle effect of soluble polysulfide intermediates,?2?the poor electronic conductivity of sulfur and?3?the volume variation of the cathode during cycling,often lead to sluggish electrode kinetics and poor active material utilization.In this paper,high graphitized carbon materials have been used to improve the cathode of lithium sulfur batteries.The main contents are as follows:?1?CNTs/graphene composite with three-dimensional network structure was obtained by ultrahigh temperature treatment at 2850?.This composite was used as the host material for the sulfur.The three-dimensional network structure of the composite and the improvement of conductivity and thermal conductivity after ultra high temperature treatment could greatly accelerate the transfer of electron/ion,and displayed excellent performance for the lithium sulfur battery at high current rates.The 2850CNTs-Gra-S cathode delivered the specific capacity of 273mAhg^-1 after 1500 cycles at a current rate of 15C and exhibited an extremely low capacity degradation of 0.0087%per cycle.?2?A porous carbon-sulfur coupled with high graphitized graphene?PC-S@2850Gra?electrode was obtained by coating a layer of high graphitized graphene?2850Gra?on the surface of the porous carbon loaded sulfur.When the sulfur loading of the cathode was added to 4.2mg cm^-2,PC-S@2850Gra displayed a initial discharge capacity of 1165m Ah g^-1 and the excellent discharge capacity of 556 mA h g^-11 after 150cycles at 0.5C rate.