The Construction Of The Efficient Cathode Material Of Lithiun-sulfur Battery Based On The Mental Organic Framework Consthructure Of ZIF-8 And MIL-47(V)

Lithium sulfur battery is one of the ideal choices for the next generation of energy storage system,due to the advantages of high specific capacity(1675 m A h g^-1),low toxicity,abundant sulfur reserves.However,problems caused by the characteristics of lithium sulfur batteries,such as poor conductivity of reactants and products,large volume changes during charging and discharging,and "shuttle effect" formed by dissolution of intermediates,have greatly limited the commercialization step of such batteries.In order to solve the above problems,in this study,ZIF-8 and VO?acac?₂ were respectively used as carbon sources and vanadium sources,which were combined by the impregnation method.After calcination progress,vanadium dioxide@porous nanocarbon?VO₂@NC?host material with porous structure were obtained.The vanadium dioxide@porous nanocarbon/sulfur?VO₂@NC/S?composite material obtained by compositing with sulfur retains great cyclic stability(482 m A h g^-1 after 1000 cycles at 1 C),and the rate performance(504 m A h g^-1 released at 2 C).In addition,in order to avoid the morphology distortion caused by the impregnation process,MIL-47?V?was used as the direct source of carbon and vanadium for the first time in this study,and vanadium trioxide@amorphous carbon?V₂O₃@C?host material with the quasi-layer cake structure were obtained by simple carbonization in one step.The sulfur-loaded vanadium trioxide@amorphous carbon/sulfur?V₂O₃@C/S?composite exhibited good cyclic stability?the capacity loss rate per cycle is only 0.0377 % after 1 C cycle 1000 times after?and the rate performance(663 m A h g^-1 released at 2 C)under high sulfur conditions(3.7 mg cm^-2).Combined with physical characterization,electrochemical measurement and energy storage mechanism experiment,the composite prepared has similar energy storage mechanism.Both materials take vanadium oxide as the source of polar adsorption,and cooperate with the inherent non-polar adsorption characteristics of carbon matrix to limit the occurrence of "shuttle effect" in the reaction process.The carbon matrix with high specific surface area not only enhanced the electrical conductivity of the composite,but also promoted the dispersion of polar adsorption media in the matrix,improved the overall polar adsorption capacity of the material,and further increased the utilization rate of the active material.At the same time,the dispersive composite structure accelerates the reaction kinetics in the cycling process,and finally gets great electrochemical performance.