聚吡咯/氧化钒@硫正极材料制备及其在锂硫电池中的应用

Preparation of Polypyrrole/Vanadium Oxide@Sulfur Cathode Materials and Its Application in Lithium-sulfur Batteries

采用聚吡咯/中空氧化钒@硫(PPy/H-V2O5@S)作为锂硫电池正极,其中间层极性V2O5中空球壳为硫的体积膨胀提供足够的空间并通过化学键固定多硫化物,外层聚吡咯对多硫化物的扩散起双重固定作用,并作为导电骨架提高正极导电性,共同提高正极对硫化物的固定作用,提高电池循环稳定性。PPy/H-V2O5@S正极在0. 5 C、1 C、2 C、4 C电流密度300次循环后,放电容量分别保持在825. 6 m A·h·g-1、673. 6 m A·h·g-1、625. 1 m A·h·g-1、583. 3 m A·h·g-1,库伦效率保持在98%以上,展现出极好的循环稳定性。

A polypyrrole/hollow-vanadium oxide@sulfur(PPy/H-V 2O 5/S)cathode with dual core-shell structure is designed and synthesized,which is supposed to chemically trap polysulfide by introducing polar V 2O 5,and improve the cycling stability.The middle layer polar H-V 2O 5 spheres can not only provide enough inner space for alleviating the volume expansion for sulfur,but also effectively moderate the dissolution of polysulfides by synergistic effect of structural restriction and chemical adsorption.Additionally,outside PPy shell serves as conductive frameworks and generates sufficient electrical conduction paths.Surprisingly,the discharge capacities of PPy/H-V 2O 5@S cathode are 825.6 mA·h·g-1,673.6 mA·h·g-1,625.1 mA·h·g-1 and 583.3 mA·h·g-1 at 0.5 C,1 C,2 C and 4 C respectively even after 300 cycles with the coulombic efficiencies over 98%exhibiting an excellent cycle stability.