Electrochemical Performance Of Biomass Organosulfur In Lithium Battery

With the progress of science and the development of society,high-energy storage devices play an increasingly important role in many fields such as portable electronic devices and electric vehicles.Lithium-ion batteries have the advantage of high energy density,but their applications are increasingly challenged by resources and costs;at the same time,the oxide cathode materials of lithium-ion batteries are widely dependent on non-ferrous metals such as cobalt and nickel,and the import dependence is high,which seriously affects the national energy safety.Therefore,the development of alternative cathode materials with high capacity and energy density has been an actively pursued direction in the battery community.Organosulfides are regarded as ideal cathode materials due to their advantages of more precise structure and more controllable redox mechanism.Biomass Organosulfur have the advantages of versatility,low cost,reproducibility and environmental protection,and have attracted the attention of many researchers in recent years.In this paper,the electrochemical properties of two biomass-based organosulfurs as cathode active materials were mainly studied,and the symmetric organodisulfides were tuned to make them have better electrochemical performance and cycle stability.1)Linear organosulfides are mainly studied in most of the current studies.But due to the linear molecular structure is not a minimalist structure,it cannot provide the optimal ratio of effective atoms(S)to inefficient atoms(C,H,etc.).In this study,a cyclic organosulfides,lenthionine,was used as a cathode material for rechargeable lithium batteries.Due to its capacity fading problem,a sulfur fragment acceptor,diphenyl disulfide(PDS),was introduced.It can truncate subsequent transformations directly from the source via covalent bonds to generate a series of linear molecules.This strategy increases the discharge capacity,suppresses the capacity fading,accelerates the reaction kinetics,and improves the cycling stability.2)Through the study of lithium allyl disulfide battery,it was explored whether organodisulfides also have a positive effect on other biomass-derived organosulfides.After a series of investigations,it was found that the biomass-derived organosulfide allyl disulfide(DADS)containing S-S can be used as a cathode active material in lithium-sulfur batteries.However,lithium allyl disulfide batteries have slow reaction kinetics,poor cycle stability and low coulombic efficiency during charge-discharge cycles.Through electrochemical reaction,the alkyl group in symmetric diphenyl disulfide(PDS)is substituted by allyl to form asymmetric organosulfide,and its reaction path is changed to improve the cycle stability of lithium allyl disulfide battery.The combination of two disulfides that can maximize the capacity of the base disulfide improves the utilization rate of S and maximizes the capacity to the greatest extent.