Electrospinning Prepared Tungsten Oxide/nitrogen-sulfur Co-doped Carbon Fiber For The Research Of Functional Interlayer Of Lithium-sulfur Battery

Reliable energy storage devices with high energy density are urgently required to meet the demands of thriving portable electronic devices and electric vehicles.Compared to lithium-ion batteries,lithium-sulfur batteries?LSBs?are attracting increasing attention due to their high theoretical specific capacity?1675 mA h/g?,high energy density(2600 W h kg^-1),natural abundant of sulfur,as well as environmental friendliness.However,LSBs still face great challenges:poor co nductivity of the sulfur electrode,severe shuttle effect,unstable electrode structure caused by volume expansion and the generation of lithium dendrites.Among them,the shuttle effect is one of the most important factors limiting the wide use of lithium-sulfur batteries.The intermediate discharge product polysulfides?LPSs?are highly soluble in the ether electrolyte which causes the occurrence of“shuttle effect”,leading to rapid capacity decay,poor cycling performance and low coulombic efficiency?CE?.In this work,we report on a novel tungsten oxide-decorated N,S co-doped carbon nanofibers?WO₃@NS-CNFs?interlayer fabricated by a simple electrospinning technique coupled with heat treatment process to effectively hinder the shuttle effect of LPSs and achieve stable cycling performance of LSBs.The main research content are as follows:?1?NS-CNFs and WO₃@NS-CNFs interlayer were fabricated through a conventional electrospinning technique followed by heat treatment.By placing the functional interlayer between cathode and separator,the LSBs with WO₃@NS-CNFs-0.1 interlayer exhibit more excellent performance than the LSBs with NS-CNFs-0.1 interlayer,which can be ascribed to synergistic effect of NS-CNFs and WO₃.On the one hand,the NS-CNFs can facilitate fast electrons and ions transfer,and also serve as the polysulfide trappers.On the other hand,uniformly distributed polar WO₃ can provide strong chemical anchoring sites for binding the LPSs and enhance the redox reaction kinetics,and thus significantly improve the electrochemical performance.The LSBs with WO₃@NS-CNFs interlayer exhibit excellent cycling stability with a high reversible capacity of 1080 mA h g^-1 after 100cycles at 0.2 C;a high reversible capacity of 870 mA h g^-1 at 0.5 C after 200 cycles with a low capacity decay of 0.1%per cycle.?2?In order to further explore the influence of the contents of WO₃ on the electrochemical performance of LSBs,different interlayers?WO₃@NS-CNFs-0.05interlayer,WO₃@NS-CNFs-0.1 interlayer and WO₃@NS-CNFs-0.2 interlayer?were prepared by changing the mass radio of tungsten salt.Among them,the LSBs with WO₃@NS-CNFs-0.1 interlayer show the best electrochemical performance.Through systematic characterization and analysis,the reason is proposed.The concentration of WO₃ in WO₃@NS-CNFs-0.05 interlayer is small and the adsorption sites are not enough,so the adsorption capacity of LPSs is limited.The large concentration of WO₃in WO₃@NS-CNFs-0.2 interlayer cause the formation of granular mixture in the carbon nanofibers,which is not conducive to the adsorption of LPSs.The LSBs with optimal WO₃@NS-CNFs-0.1 interlayer show the best electrochemical performance:even at high sulfur loading of 3.2 mg cm^-2,the LSBs with WO₃@NS-CNFs-0.1interlayer still maintains at 740 mA h g^-1 at 0.5 C after 100 cycles.