| As global energy demand continues to grow,it is critical to replace traditional lithium-ion batteries by high energy density and low cost energy storage systems replace.Lithium-sulfur battery has excellent research and development value due to its high theoretical specific capacity(1675 mA h g-1)and energy density(2600 Wh Kg-1).What’s more,sulfur is low-cost,environmentally friendly,non-toxic and widely available.Therefore,lithium-sulfur batteries are expected to be the next generation of highly promising energy storage systems.Although lithium-sulfur batteries have great potential,they were hindered by the"shuttle effect"caused by the dissolution of polysulfides（PSs）in organic electrolytes.Elemental sulfur is reduced to polysulfides in the discharge process,the soluble polysulfides will dissolve in the electrolyte and arrive to the negative electrode through the membrane undergoing a series of side reactions with the negative lithium.This shuttle phenomenon results in a loss of sulfur active material,high battery impedance,a sharp decline in battery capacity,limited rate performance and low sulfur utilization.This paper analyzes and summarizes the research status and development of lithium-sulfur batteries,and solves the"shuttle effect"problem of polysulfides simultaneously ensuring excellent lithium ion mobility,thereby improving the overall performance of the battery.（1）Amino-functionalized mesoporous silica nanosheets（FMSiNP）interlayer material:Mesoporous silica nanosheets（MSiNP）were synthesized using graphite oxide（GO）as a template.Amino-functionalized silane coupling agent was reacted with MSiNP to obtain FMSiNP.By simple blade coating,the two-dimensional nanosheets can be stacked closely between them on the positive electrode.Introducing N atoms and mesoporous structures in FMSiNP simultaneously leads to the resultant interlayere possess chemically absorb and physically block.In addition,the FMSiNP has excellent chemical stability and rich mesoporous structure ensuring the interlayer with good ionic conductivity.The lithium-sulfur battery coated with the functional interlayer exhibited good cycle stability,high coulombic efficiency and excellent rate performance.At a current rate of 1.0 C,the initial discharge capacity of the battery is 1080 mA h g-1.After 1500 cycles,the discharge capacity is 486 mA h g-1,the capacity decay rate is 0.038%per cycle,the Coulomb efficiency is 99%,and the capacity is 574 mA h g-1 at a current rate of 4.0 C.（2）Polyethyleneimine（PEI）modified reduced graphite oxide（RGO）（PEI-RGO）interlayer material:The PEI-RGO was obtained through modifying the GO with PEI through electrostatic attraction and subsquently reduced by hydrazine hydrate.RGO has good electrical conductivity,can be used as a secondary current collector.The amino-functional group has a strong chemical interaction with the polysulfides.The PEI-RGO was bladed onto the positive electrode by using carboxymethyl cellulose（CMC）as binder.The lithium sulfur battery with the PEI-RGO functional interlayer exhibits good cycle stability,high coulombic efficiency and excellent rate performance.At a current rate of 1.0 C,the initial discharge capacity of the battery is 1121 mA h g-1.After 300 cycles,the discharge capacity is812 mA h g-1,the capacity decay rate is 0.091%per cycle. |
