The Preparation Of Polyaniline Nano Fiber-based Carbon Composites And Its Application In Lithium Sulfur Batteries

At present,electric vehicles,a variety of portable electronic products and other industries on the power supply safety,capacity and other requirements are getting higher and higher,the demand for the development of excellent performance,green environmental protection of the secondary battery is urgent.Lithium-sulfur batteries with theoretical capacity,low toxicity,low cost,is considered one of the most development potential of the secondary battery of the future.However,the lithium-sulfur battery presence series of problems,such as the use of low active substance reunion,shuttle effect,capacity fading fast,which restrict its practical application.In view of many problems existing in the application of lithium sulfur battery,polyaniline nano fiber based carbon/sulfur composites were prepared,and their preparation methods and electrochemical properties were studied.The experimental results show that the sulfur carbon composite has excellent electrochemical performance,the main content includes the following aspects:1.The use of solution polymerization,doped with hydrochloric acid,ammonium persulfate(APS)as initiator,synthesized polyaniline nanofibers,by optimizing the reaction conditions:aniline(ANI)concentration,aniline and APS molar ratio([ANI][APS]),were successfully prepared the excellent electrochemical performance of hydrochloride doped nano fibrous polyaniline,The results of SEM test showed that the morphology of the product was fibrous,and the distribution was more uniform.2.Treating the nano fibrous polyaniline through high temperature carbonization prepared polyaniline nano fiber based carbon(PANI(c),the effect of different carbonization temperature(700 ??800 ? 900?)on composite material properties was discussed.In this paper,by means of SEM,XRD,electrochemical workstation test method,the materials were characterized and researched.The test results showed when the carbonization temperature is 800 ?,the synthesis of PANI(c)has better fiber morphology,and in lmv/s scan rate,the maximum specific capacitance is 26.003 F·g-1.3.Sodium thiosulfate and hydrochloric acid are on a polyaniline-based carbon nanofibers by liquid phase deposition sulfur,it generated carbon coated sulfur carbon composite materials,Using SEM,TG,SEM and other testing methods to characterize and study its morphology,composition and structure,Test results show that in the three kinds of sulfur carbon composite,the S-PANI(c)60%is mixed evenly,nano sulfur is tightly packed in PANI based carbon fiber,sulphur is wrapped with by carbon fiber net,two kinds of materials achieve the close contact,provide favorable reaction conditions for the electrochemical.Through the electrochemical workstation and the electrochemical performance test system test the electrochemical performance of lithium sulfur battery assembled by the composite materials.AC impedance measurements showed that the composite sulfur content is less,the battery interface impedance is small,can show the good performance of the battery,charge and discharge,cycling performance and cyclic voltammetry showed that composite has good electrochemical reversible and coulombic efficiency.The cycle performance of the battery is related to the pore structure of the carbon material,which indicates that the carbon nano fiber has a porous structure,which can effectively contain lithium.S-PANI(C)60%showed the best electrochemical performance in the three kinds of sulfur carbon composites.In 1C,2C rate conditions,the initial discharge capacity was 917.2,761.0 mAh·g-1.After 100 cycles,the capacity retention rate was 65%,59%,respectively,which shows good electrochemical performance.