硫掺杂二氧化钛/碳化钛复合材料的制备及储锂性能

通过二维层状Ti_3C_2的原位水热氧化和气相硫化反应,制备了硫掺杂二氧化钛/碳化钛(S-TiO_2/Ti_3C_2)复合材料,并用于电化学储锂。结果表明,二氧化钛纳米颗粒原位生长在碳化钛片层上,且硫成功掺杂到二氧化钛中。这种S-TiO_2/Ti_3C_2复合结构作为锂离子电池的负极材料,表现出较好的电化学性能。在0.2 A/g的电流密度下循环100圈后,放电比容量稳定在288 m A·h/g,远高于纯Ti_3C_2和TiO_2/Ti_3C_2电极的放电比容量。S-TiO_2/Ti_3C_2复合材料表现出的较高比容量和良好的循环性能,主要归因于复合材料的特殊纳米结构优势:二氧化钛原位生长在碳化钛上,使复合材料具有稳定良好的接触界面,能够促进电子的快速转移,同时可以有效避免循环过程中两种组分的分离;硫在二氧化钛中的掺杂可以提高二氧化钛的导电性,并引入缺陷,提高反应活性。此研究工作为二维材料的原位转化及复合提供了新的思路和研究方法。

Preparation and Lithium Ion Storage Performance of Sulfur-Doped Titanium Dioxide/Titanium Carbide Composite

Sulfur-doped titanium dioxide/titanium carbide(S-TiO₂/Ti₃C₂)composites were prepared via in-situ hydrothermal oxidation and chemical vapor phase sulfurization using two-dimensional layered Ti₃C₂ as the raw material. The results show that the TiO₂ nanoparticles in situ grew on the Ti₃C₂ nanosheets and sulphur was successfully doped into titanium dioxide. The S-TiO₂/Ti₃C₂ composite as anode material for lithium ion batteries exhibits superior electrochemical performance. A discharge specific capacity of 288 mA·h/g can be obtained after 100 cycles at a current density of 0.2 A/g, which is much higher than those of TiO₂/Ti₃C₂ and pure Ti₃C₂ electrodes. The outstanding cycle stability and discharge specific capacity of the S-TiO₂/Ti₃C₂ electrode are attributed to following reasons:TiO₂ nanoparticles electrically contacting Ti₃C₂ nanosheets can facilitate the interfacial electron transfer and effectively avoid the separation of the two components during the cycle. In addition, S-TiO₂ can improve the conductivity of the TiO₂ and produce some defects to enhance the reactivity. This work provides a new strategy for the preparation of two-dimensional composite materials through an in-situ transformation.