Synthesis And Electrochemical Properties Of Disulfide/Carbon Composites

The development in new types of cathodes and anodes of low-cost,environmental friendly and high-capacity,has become a hotspot and focus for the advancement of clean-energy commercialization.However,the graphite anode widely used has its disadvantages such as overcharge poor stability,low specific capacity and low safety.While the commercial cathode has disadvantages of low tap density,poor conductivity etc..Therefore,we combine disulfides?FeS2,MoS₂?of high capacity with carbon of high conductivity.Composites with remarkable electrochemical properties were successfully fabricated.The main contents are as below:1)Cotton T-shirts were used as both the bio-templates and the carbon resources to fabricate FeS₂@S-C composite.Effect of different Fe2+ concentrations on the composite structure and electrochemical performance was investigated.Results showed that the FeS₂ nanoparticles fabricated using 0.2 M FeSO₄ formed more uniform morphology and possessed smaller size,as well as the best electrochemical properties.It retained a high reversible specific capacity of 689 mAh g^-1 after 100 cycles at current density of 0.1 A g^-1,and even at 2 A g^-1,the reversible capacity was still as high as 400 mAh g^-1,suggesting excellent cycling stability and rate capability.2)GO was synthesized via modified Hummers method.Afterwards,MoS₂ @GO was integrated via a hydrothermal process using ammonium molybdate and thioacetamide as precursors followed by heat treatment.The effect of different mole ratios of MoS₂ and Graphene on the structure and electrochemical performance was studied.It showed that when the mole ratio of MoS₂ and Graphene is 1:1,the composite with three-dimensional flocculent structure exhibited the best electrochemical properties.As an anode,it delivered the specific capacity of 879 mAh g^-1 at 0.1 A g^-1 after 50 cycles with almost no degradation.Moreover,it also showed a reversible capacity of ⁵30 mAh g^-1 even at 2 A g^-1.When the current density returned to 0.1 A g^-1,the capacity recovered to the original value,showing a superior rate capability.3)When MoS₂ @GO was integrated with sulfur,we studied the electrochemical performance of the composite as the cathode for lithium-sulfur battery.Compared to pure sulfur electrode,the cycling stability of MG1@S was much enhanced.It delivered the discharge/charge capacity of 534.1/535.5 mAh g^-1 after 50 cycles,and its columbic efficiency was about 100%,capacity retention rate was 92.9% comparing to the second cycle.