Du Juntao, Ma Jiangkai, Liu Zetao, Wang Wenchao, Jia Huina, Zhang Minxin, Nie Yi
Zhengzhou Institute of Emerging Industrial Technology Zhengzhou 450000 China
Zhengzhou University Zhengzhou 450000 China.
RSC Adv. 2022 Jul 19;12(32):20672-20678. doi: 10.1039/d2ra01997c. eCollection 2022 Jul 14.
It is essential to consider the controllable microstructure of soft carbon and its enhancement effect on the electrochemical performance of silicon (Si) active materials. In this study, a series of Si@mesocarbon microbead (Si@MCMB) composites were prepared using mesophase pitch as the soft carbon source to coat nano-Si. The results showed that the ordered carbon layer stacking of soft carbon increased slightly with increasing heat treatment temperature in the range of 800-1400 °C. The Si@MCMB composites at higher temperature had a turbostratic carbon layer texture with rich porosity and smaller specific surface area, and had good cycle stability and high rate performance. These results highlighted that the co-existing structure of turbostratic carbon arrays with abundant porosity from soft carbon, provided the electron/ion transfer channels, underwent Si alloy volume change and enhanced the mechanical stability. Importantly, the relationship between the capacity retention rate of the Si@MCMB anodes and the microstructural characteristics (carbon layer and porosity) of soft carbon was established, which provided effective guidance for the design of high-performance silicon/carbon (Si/C) anode materials.
考虑软碳的可控微观结构及其对硅（Si）活性材料电化学性能的增强作用至关重要。在本研究中，以中间相沥青为软碳源制备了一系列用于包覆纳米硅的硅@中间相碳微球（Si@MCMB）复合材料。结果表明，在800 - 1400℃范围内，随着热处理温度的升高，软碳的有序碳层堆积略有增加。较高温度下的Si@MCMB复合材料具有富含孔隙且比表面积较小的乱层碳层结构，具有良好的循环稳定性和高倍率性能。这些结果表明，来自软碳的具有丰富孔隙的乱层碳阵列共存结构提供了电子/离子传输通道，承受了硅合金的体积变化并增强了机械稳定性。重要的是，建立了Si@MCMB负极的容量保持率与软碳微观结构特征（碳层和孔隙率）之间的关系，这为高性能硅/碳（Si/C）负极材料的设计提供了有效指导。
