Hu Shan, Chen Wen, Uchaker Evan, Zhou Jing, Cao Guozhong
State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, School of Materials Science and Engineering, Wuhan University of Technology, Wuhan, 430070 (P. R. China), Fax: (+86)27-87760129.
Department of Materials Science and Engineering, University of Washington, Seattle, Washington, 98195 (USA).
Chemistry. 2015 Dec 7;21(50):18248-57. doi: 10.1002/chem.201503356. Epub 2015 Oct 30.
MoS2 nanocrystals embedded in mesoporous carbon nanofibers are synthesized through an electrospinning process followed by calcination. The resultant nanofibers are 100-150 nm in diameter and constructed from MoS2 nanocrystals with a lateral diameter of around 7 nm with specific surface areas of 135.9 m(2) g(-1) . The MoS2 @C nanofibers are treated at 450 °C in H2 and comparison samples annealed at 800 °C in N2 . The heat treatments are designed to achieve good crystallinity and desired mesoporous microstructure, resulting in enhanced electrochemical performance. The small amount of oxygen in the nanofibers annealed in H2 contributes to obtaining a lower internal resistance, and thus, improving the conductivity. The results show that the nanofibers obtained at 450 °C in H2 deliver an extraordinary capacity of 1022 mA h g(-1) and improved cyclic stability, with only 2.3 % capacity loss after 165 cycles at a current density of 100 mA g(-1) , as well as an outstanding rate capability. The greatly improved kinetics and cycling stability of the mesoporous MoS2 @C nanofibers can be attributed to the crosslinked conductive carbon nanofibers, the large specific surface area, the good crystallinity of MoS2 , and the robust mesoporous microstructure. The resulting nanofiber electrodes, with short mass- and charge-transport pathways, improved electrical conductivity, and large contact area exposed to electrolyte, permitting fast diffusional flux of Li ions, explains the improved kinetics of the interfacial charge-transfer reaction and the diffusivity of the MoS2 @C mesoporous nanofibers. It is believed that the integration of MoS2 nanocrystals and mesoporous carbon nanofibers may have a synergistic effect, giving a promising anode, and widening the applicability range into high performance and mass production in the Li-ion battery market.
通过静电纺丝工艺随后进行煅烧，合成了嵌入介孔碳纳米纤维中的二硫化钼（MoS₂）纳米晶体。所得纳米纤维直径为100 - 150纳米，由横向直径约为7纳米的MoS₂纳米晶体构成，比表面积为135.9平方米每克。将MoS₂@C纳米纤维在450℃的氢气中进行处理，并将对比样品在800℃的氮气中退火。这些热处理旨在实现良好的结晶度和所需的介孔微观结构，从而提高电化学性能。在氢气中退火的纳米纤维中少量的氧有助于获得较低的内阻，进而提高导电性。结果表明，在450℃氢气中获得的纳米纤维具有1022毫安时每克的非凡容量和改善的循环稳定性，在100毫安每克的电流密度下经过165次循环后容量损失仅为2.3%，以及出色的倍率性能。介孔MoS₂@C纳米纤维动力学和循环稳定性的大幅改善可归因于交联的导电碳纳米纤维、大比表面积、MoS₂的良好结晶度以及坚固的介孔微观结构。所得的纳米纤维电极具有短的质量和电荷传输路径、改善的导电性以及暴露于电解质的大接触面积，允许锂离子快速扩散通量，这解释了界面电荷转移反应动力学和MoS₂@C介孔纳米纤维扩散率的改善。据信，MoS₂纳米晶体和介孔碳纳米纤维的整合可能具有协同效应，提供一种有前景的负极，并扩大在锂离子电池市场中高性能和大规模生产的适用范围。
