自组装二氧化锰纳米片包覆嵌硫多通道碳纳米纤维复合物在锂硫电池阴极中的应用

由于可充电锂硫电池在能量密度方面具有显著的优势,因此被认为是很有前途的下一代储能体系.然而,多硫化物的穿梭和硫的绝缘特性,导致了锂硫电池严重的容量衰减和低硫利用率,阻碍了它们的实际应用.因此,本研究合理设计制备了一种二氧化锰纳米片包覆嵌硫多通道碳纳米纤维复合物用于锂硫电池阴极.多孔多通道碳纳米纤维的高导电性促进了电极中电子和离子的传输动力学,多孔结构将硫包裹并隔离在其内部空隙中,在物理上延缓了高阶多硫化物的溶解.此外,二氧化锰壳层对高阶多硫化物的物理限制和化学吸附相结合,可以隔离长时间充放电循环后从碳基体中泄漏的多硫化物,从而进一步提高电极的电化学性能.

In situ assembly of MnO2 nanosheets on sulfur-embedded multichannel carbon nanofiber composites as cathodes for lithium-sulfur batteries

Rechargeable lithium-sulfur batteries have been regarded as the promising next generation energy storage system due to their overwhelming advantages in energy density.However,their practical implementations are hindered by severe capacity fading and low sulfur utilization,which are caused by polysulfide shuttling and the insulating nature of sulfur.Herein,sulfur-embedded porous multichannel carbon nanofibers coated with MnO2 nanosheets(CNFs@S/MnO2)are rationally designed and fabricated as cathode for lithiumsulfur battery.The high conductivity of porous multichannel carbon nanofibers facilitates the kinetics of electron and ion transport in the electrodes,and the porous structure encapsulates and sequesters sulfur in its interior void space to physically retard the dissolution of high-order polysulfides.Moreover,the MnO2 shell exhibits a combination of physical and chemical adsorption for high-order polysulfides,which could sequester polysulfides leaked from the carbon matrix after long-time charge/discharge cycles,resulting in enhanced cyclic stability.As a result,the electrode delivers a specific capacity of 1286 m A h g^-1 at 0.1 C and 728 m A h g^-1 at 3 C.And the capacity could remain 774 m A h g^-1 after 600 cycles at 1 C.