Research On Inhibition Strategy Of Sulfur Electrode Dissolution And Shuttle Effect In Sulfur-based Batteries

In recent years,sulfur-based batteries with multi-electron transfer reaction mechanisms have been highly anticipated as a potential alternative to traditional lithium-ion batteries due to their high specific capacity,abundant resource,and low cost.Despite their advantages,sulfur-based batteries still face several unresolved issues,including the "shuttle effect" during the redox reaction,dissolution of sulfur during the electrochemical reaction,and poor conductivity of sulfur and its discharge intermediates.To provide a reasonable solution to these problems and construct a high-energy-density sulfur-based secondary battery,this dissertation focuses on optimizing and modifying the positive electrode material,electrolyte,and separator to suppress the dissolution and shuttle effect of the sulfur electrode and improve the conductivity of the battery system.The main research contents of this dissertation are as follows:(1)Carbon felt(CF)intermediate layer was prepared by simply carbonizating the Xuan paper and placed between the sulfur electrode and separator.This layer effectively slows down the dissolution of the sulfur electrode,prevents the shuttle effect of polysulfides(Li PSs)from damaging the negative electrode and separator,and reduces the polarization effect inside the battery,thus improving the electrochemical performance of the lithium-sulfur battery.Experimental results show that introducing the CF intermediate layer can significantly improve the electrochemical performance of the lithium-sulfur battery.At a current density of1667 m A/g,the initial discharge specific capacity of the sulfur electrode can reach 1016.7m Ah/g.After 300 cycles,the discharge specific capacity can still remain at 850.7 m Ah/g with a capacity retention rate of 84.6%.Thw capacity decay rate was only 0.054% per cycle.(2)High-concentration dual-salt-in-water(Wi BS)electrolyte was prepared to significantly suppress the generation and shuttle of Li PSs and thus delay the dissolution of the sulfur electrode.On the basis of solidifying and inhibiting Li PSs with the Wi BS electrolyte,chitosan(CS)was introduced to form a hydrogel electrolyte,further optimizing the electrochemical performance of the aqueous lithium-sulfur battery.In the Wi BS-CS electrolyte,the initial discharge specific capacity of the aqueous lithium-sulfur full battery can reach 121.88 m Ah/g at a current density of 334 m A/g,and after 200 cycles,it can still retain96.28 m Ah/g of discharge specific capacity,with a capacity retention rate of 79.9% and a capacity decay rate of only 0.103% per cycle.(3)Zn S nanoparticles were prepared by a solvothermal method and then coated with a carbon shell to form Zn S@C nanomaterials.The addition of CF effectively suppressed the dissolution of the sulfur electrode.The first discharge specific capacity of the CF-added zinc-sulfur battery at a current density of 1000 m A/g could reach as high as 1403.13 m Ah/g.As an emerging secondary battery system,the energy density of the zinc-sulfur battery can reach up to 976.5 Wh/kg,and the cost is low.The results of this dissertation provides a new research direction for the application of sulfur-based materials in the field of batteries.