碗状C@FeS2@NC复合材料的制备及其电化学性能

在二氧化硅微球表面包覆一层酚醛树脂并在高温下将其转化为碳壳，然后进行溶剂热反应、多巴胺包覆、高温硫化以及氢氧化钠刻蚀，制备出碗状C@FeS₂@NC(氮掺杂碳层)复合材料。这种复合材料具有开放性三维碗状结构，能释放体积变化产生的应力，其较大的比表面积(70.67 m²·g^-1)有很多的活性点位。内外双层碳壳提高了这种复合材料的导电性并提供了稳定的机械结构，外层NC具有很好的保护作用。将这种复合材料用作锂离子电池负极，在0.2 A·g^-1电流密度下首圈放电比容量和充电比容量分别为954.3 mAh·g^-1和847.2 mAh·g^-1，对应的首圈库伦效率为88.78%。循环100圈后，其放电比容量稳定在793.8 mAh·g^-1。

Preparation and Electrochemical Properties of Bowl-shaped C@FeS2@NC Composites

The bowl-like C@FeS₂@NC (nitrogen doped carbon layer) composites were prepared via a multi-step process, namely the silicon dioxide microspheres were firstly coated with phenolic resin and then converted into carbon shell at high temperature, soon after which were subjected to solvothermal reaction, dopamine coating, high temperature vulcanization and sodium hydroxide etching. This composite material has an open three-dimensional bowl-like structure, which can well release the stress caused by volume change. Its large specific surface area (70.67 m²·g^-1) has a lot of active sites. The double carbon shell composite consisted of an inner and an outer carbon shells, as a stable mechanical framework, can enhance the electrical conductivity, while the outer NC has a good protective effect. When this composite material is used as the negative electrode of lithium-ion battery, the discharge specific capacity and charge specific capacity of the first turn are 954.3 mAh·g^-1 and 847.2 mAh·g^-1, respectively at the current density of 0.2 A·g^-1, and the corresponding Coulomb efficiency of the first turn is 88.78%. After 100 cycles, the discharge specific capacity is stable at 793.8 mAh·g^-1.