多壁纳米碳管约束二硫化锡作为锂离子电池负极的电化学行为

通过两步法制备多壁纳米碳管约束SnS_2纳米材料(SnS_2@MWCNT)。采用直流电弧等离子体法在甲烷气氛下制备多壁纳米碳管约束金属锡纳米结构(Sn@MWCNT)作为前驱体,再通过硫化反应获得SnS_2@MWCNT纳米结构。对材料进行Raman、X射线衍射(XRD)、透射电镜(TEM)等物理表征的结果显示多壁纳米碳管长约400nm,表面碳层晶化程度良好,碳层厚度约10 nm。以Sn S2@MWCNT纳米结构作为负极材料的锂离子电池显示出较为良好的电化学性能。其首次充放电库伦效率为71%,循环50次后,容量仍保持703 mAh?g~(-1)。SnS_2@MWCNT纳米结构电极的高容量特性源于多种活性物质共同提供容量,且各物质反应平台不同。平台呈现明显阶梯型,缓解了体积膨胀效应对电极材料的破坏。

Electrochemical Behavior of MWCNT-Constraint SnS2 Nanostructure as the Anode for Lithium-Ion Batteries

Multi-walled carbon nanotube constrained SnS₂ (SnS₂@MWCNT) nanostructure is successfully realized through a facile 2-step process. Firstly, DC arc-discharge method is applied to fabricate Sn@MWCNT nanoparticles as the precursor that is subsequently converted into SnS₂@MWCNT through low-temperature vulcanization. Various analytical methods, including powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy, are used to ascertain the microstructure and morphology of the SnS₂@MWCNT nanoparticles. The results show that the SnS₂@MWCNT nanoparticles have a uniform structure of SnS₂ half-filled MWCNTs with average thickness of 10 nm and average length of ~400 nm. The electrochemical properties of the as-prepared SnS₂@MWCNT nanoparticles are studied using the nanoparticles as anode materials in Li-ion batteries. The SnS₂@MWCNT electrode presents high initial Coulombic efficiency of 71% and maintains a capacity of 703 mAh·g^-1 after 50 cycles. Excellent performance of the batteries benefits from the active electrochemical reactions of various chemical components, multi-step lithiation/delithiation behaviors, and the structural constraint from the MWCNTs.