| The lithium/sulfur battery is a promising electrochemical system that has a hightheoretical capacity of1675.0mAh/g. In this article, the author mainly worked on thestudy of the cathode materials of lithium sulfur battery, and the work can be divided intotwo aspects:（1） The author used a onestep way synthesis method to get aMWCNT/sulfur/polypyrrole composite cathode with a dual core-shell structure.The conductive polypyrrole coating on the sulfur/MWCNT facilitates fastelectron transport enabling the material with superior electrochemical stability,rate capability, and cyclability in lithium-ion batteries. This composite has asulfur content of70.0wt.%, and has a good electrochemical performance.Charged and discharged at200.0mA/g, and cycled for50cycles, it can maintaina capacity of855.0mAh/g; Charged and discharged at1000.0mA/g, and cycledfor100cycles, the capacity can still maintain at855.0mAh/g. And the authorhas proved the structure through TEM, SEM, XRD ect. test.（2） The author combined grapheme, porous carbon, acetylene black with sulfurand had done a lot of works. The author had study the different methods of thecombination of sulfur and those materials. The composite of grapheme combinedwith sulfur performance well, with a first discharge capacity of1550.0mAh/g.The electrochemical results show that Charged and discharged under1000.0mA/g, cycled for100times, its capacity can still remained at764.0mAh/g, and577.0mAh/g under2000.0mA/g, also with good rate performance. The porouscarbon and sulfur composite with82.0wt.%S, behaved bad and it can beattributed to the high sulfur content, exceed the maximal capacity of loadingsulfur, leading to the ineffective utilization of sulfur and its electrochemicalperformance need to be improved. A nanostructured sulfur/acetylene blackcomposite showed a good coating with sulfur, and proved that the method ofloading sulfur into acetylene black is very suit to this material, but theelectrochemical performance is very poor, and need further research. |
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