Study On Synthesis Process Of Core-shell S@PANi-C As Cathode Materials For Lithium-sulfur Batteries

In view of the S@PANi-C composite cathode materials synthesis process of liquid phase method is complex,inefficient and it s difficult to industrialize,the technological route of the ball milling method for direct synthesis of core-shell structured S@PANi-C composite cathode materials with high sulfur content was studied firstly,based on the step-by-step method of liquid phase reported in papers and the electrochemical performance of S?PANi and S@PANi-C cathode materials,including the discharge-charge cycle performance,AC impedance and cyclic voltammograms.Next,the micron sulfur synthesis process and its application in core-shell S@PANi-C composite cathode materials synthesized by the ball milling method was studied.The main results are as follows:(1)The direct synthesis process of core-shell structured S@PANi-C by the ball milling method was studied,it has advantages of simple process,high efficiency,short cycle and low cost and high industrial application characteristics compared with the step-by-step method.The synthesis technological route of S@PANi-C is as follows:disperse the sulfur particles and Super P in HCl solution with the concentration of?0.065g/mL,ball milling with 220rpm for 2h,add 3.5%?5%Aniline monom er to the reaction system and ball milling at the speed of 220rpm for 2h continuely,add(NH4)2S2O8 with the ratio of(NHa)2S2O8:Aniline=1.2:1(mol),adjust the speed of ball milling to 60rpm and keep polyreaction more than 6h?take out the composites after reaction,wash,filter,dry for 12h in vacuum,heat treatment at 200 ? for 6h finally.At 1C rate,the S@PANi-C2.0 cathode materials synthesized by the ball milling method showed discharge specific capacities are 781.9mAhlg after 11th cycles and 585.4mAh/g after 150th cycles,the total resistances is 123.47?,and the average capacity decay is 0.179%per cycle.(2)The sublimation and atomization condensation process for micron sulfur synthesis was studied,micron sulfur(7?10?m)replaced commercial sulfur,and was ap plied in the ball milling synthesis process of core-shell structurecd S@PANi-C composite cathode materials,discussed the synthetic process parameters such as PANi-C coating and Super P proportion emphatically,obtained the synthetic route that core-sheil structured S@PANi-C composites synthesized b y the ball milling method and from micron sulphur.The electrochemical performance of S@PANi-C cathode materials synthesized from micron sulfur were tested at different conditions.At temperatures of 0?50?,the S@PANi3-C1.0 cathode materials showed stable rate and cycle performance.At 1C and 2C rate,the discharge specific capacities of S@PANi3-C1.0 are 564.1mAh/g and 442.5mAh/g after 300 cycles respectively,the average capacity decay less than 0.1%per cycle,showed high discharge specific capacities and good cycle stability.