Application Of Bimetal Chalcogenide Compound As Cathode In Lithium-sulfur Batteries

Shuttle effect has always been a thorny problem in lithium-sulfur batteries.This paper has made corresponding improvements to it.FeSb₂S₄、Mn₂Sb₂O₇、FeSbO₄ series of bimetallic chalcogenides are added to the positive electrode material to form strong chemical bonds to capture more Sulfides,thereby inhibiting the migration behavior of polysulfides;in turn,can significantly improve electrochemical performance,so they are used as active sulfur storage substrates for lithium-sulfur battery cathodes for research.With FeSb₂S₄ as the positive electrode carrier adsorbent,we prepared FeSb₂S₄ and studied its application in lithium-sulfur batteries.The analysis of ultraviolet-visible absorption spectroscopy shows that Mn₂Sb₂O₇ is adsorbed by FeSb₂S₄.The test results show that FeSb₂S₄ has a strong affinity for polysulfides.Combined with the results of visual adsorption experiments and XPS research and analysis,it is proved that FeSb₂S₄ not only has physical adsorption with polysulfides,but also has chemical adsorption.Through cyclic voltammetry test and analysis,it can reach 1287.4 m Ah g^-1at a rate of 0.5C,and after a long cycle of 1000 cycles,the S/FeSb₂S₄/CNTs electrode can still maintain a high capacity.In the experimental section of Mn₂Sb₂O₇,the S/Mn₂Sb₂O₇/CNTs electrode showed good adsorption and cycle stability.UV-vis spectroscopy shows that Li₂S₆is adsorbed by Mn₂Sb₂O₇,and XPS shows that Mn₂Sb₂O₇and Li₂S₆are chemically adsorbed and shifted.These test results show that Mn₂Sb₂O₇has a strong affinity for polysulfides.Further through the electrochemical performance test,through the step cycle performance,the discharge capacity of the S/Mn₂Sb₂O₇/CNTs electrode reached1057.5 m Ah g^-1under the 2C rate long cycle,reflecting its excellent discharge performance,even at 0.1C-2C In the stepped cycle test,it can show good capacity under different magnifications.In the last experimental chapter,FeSbO₄can increase the force with soluble polysulfides and improve the shuttle effect,which strongly shows that the composite electrode S/FeSbO₄/CNTs improves the electrochemical performance of lithium-sulfur batteries.The material has excellent expressive power and can still reach a high capacity of 1070.8 m Ah g^-1after 800 cycles of 2C.The experimental procedure for the synthesis of FeSbO₄is simple,with practicality and potential for large-scale applications.And unlike the previous strategy of capturing polysulfides through physical barriers or simple surface interactions,this chemical adsorption is very effective.