中孔炭微球/MoS2/S复合正极材料的制备及其电化学性能

Synthesis and electrochemical performance of S/mesoporous carbon microsphere-MoS2 cathode materials

  • 摘要: 目前锂硫电池的应用仍受活性物质硫和放电产物的绝缘性、中间产物聚硫化物的穿梭以及硫正极在循环过程中较大的体积变化等问题限制。本文以导电中孔炭微球(MCM)为载体材料,将极性的MoS2均匀地负载于MCM框架中,作为高效的硫正极载体材料。结果表明,与MCM/S正极相比,添加了MoS2的MCM/MoS2/S复合正极表现出更高的容量、更好的循环稳定性和倍率性能,其中添加12.4 wt.%的MoS2表现最优异的电化学性能。此外,MoS2在硫正极的工作电压窗口内具有电化学活性,可以提供附加容量,且能在醚系电解液中保持稳定的放电容量。当用MoS2替代部分非电化学活性的载体时,可以提高硫正极的整体容量。这种利用电化学活性的载体提高电极整体容量的思路为进一步提高硫正极的电化学性能提供了参考。

     

    Abstract: The commercial uses of Li-S batteries are still greatly limited by a number of obstacles such as the insulating nature of sulfur and its discharge products, the shuttling of intermediate polysulfides and the large volume change of sulfur during cycling. Here, we attached polar MoS2 to a well-developed mesoporous carbon microsphere (MCM) framework and used this as a highly efficient host for the sulfur cathode. Compared with a S/MCM cathode, the S/MCM-MoS2 cathode provided a higher discharge capacity, improved cycling stability and rate performance with an optimum MoS2 content of 12.4 wt.%. MoS2 is electrochemically active within the working voltage range of the sulfur cathode, which contributes extra capacity to the sulfur cathode with a stable cycling performance without loss of capacity in a 1 M LiTFSI electrolyte. The replacement of some of the electrochemically inactive carbon with MoS2 also increases the overall energy density. The exploration of such an electrochemically active host material may provide a new possibility for improving the electrochemical performance of Li-S batteries.

     

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