硅灰制备硅/碳化硅纳米复合材料及其储锂性能研究

Synthesis of Silicon/Silicon Carbide Nanocomposites from Silica Fumeand Investigation of Its Lithium Storage Performance

硅负极的体积效应导致锂离子电池的循环寿命短且容量迅速衰减,如何提高硅负极材料的循环稳定性至关重要。采用了熔盐辅助镁热还原法,通过使用含有单质碳的工业固体废弃物硅灰,成功设计了一种碳化硅增强的硅纳米材料(SF-Si),所制备的SF-Si样品不仅保留了SF本身存在的SiC,还将单质碳转化为SiC,使样品中的SiC含量达到了16.4%(质量分数)。与经过热处理去除单质碳的硅灰制备的硅材料(H-SF-Si)相比,SF-Si负极材料表现出更好的循环性能和倍率性能,即第1圈2584.76 mAh·g^(-1)的高比容量和第100圈时具有83%的容量保持率,并且在高电流密度5 A·g^(-1)下的平均容量仍为877.28 mAh·g^(-1),这主要归因于更高的SiC含量。研究表明,硅灰在锂离子电池硅负极领域具有应用潜力,其碳元素在制备硅基纳米材料时发挥积极的作用。

The volumetric expansion of silicon anodes in lithium-ion batteries leads to a shortened cycling life and rapid capacity decay.Consequently,it is imperative to enhance the cyclic stability of silicon anode materials.In this study,we employed a molten salt-assisted magnesiothermic reduction method and successfully devised a silicon nanomaterial reinforced with silicon carbide(SF-Si)by utilizing silica fume containing elemental carbon,which is an industrial solid waste.The resulting SF-Si sample not only retained the SiC present in the silica fume but also converted the elemental carbon into SiC,achieving a SiC content of 16.4%(mass fraction).Comparative analysis with silicon material prepared from heat-treated silica fume without elemental carbon removal(H-SF-Si)revealed that SF-Si exhibited superior cyclic and rate performance.It attained a high specific capacity of 2584.76 mAh·g^(-1) in the first cycle,maintained an 83%capacity retention after 100 cycles,and even at a high current density of 5 A·g^(-1),the average capacity remained at 877.28 mAh·g^(-1).These enhancements were primarily attributed to the higher SiC content.The study underscores the potential application of silica fume in the domain of silicon anodes for lithium-ion batteries,with its carbon element playing a constructive role in the preparation of silicon-based nanomaterials.