多级结构硅基负极材料的制备及电化学性能

Preparation and Electrochemical Performance of Silicon-Based Anode Materials with Hierarchical Structure

高比容量、最高体积容量、高储量使硅基材料倍受关注。硅低导电性以及在充放电过程中体积效应大、固态电解质界面(SEI)膜不稳定等问题,导致循环性能较差,制约硅基负极材料的高性能应用。本文通过三层同轴静电纺丝技术将ZIF-67、聚甲基丙烯酸甲酯(PMMA)、聚丙烯腈(PAN)、Si制备出多级结构的纳米纤维,以解决硅基负极材料的缺陷问题。由于ZIF-67和PMMA的加入,提高了复合材料的石墨化程度(ID/IG值降至0.96),导电性得以提高。同时也提高了离子扩散速率和电荷转移效率。经过优化,[Si/C]@[ZIF-67/C]负极材料在0.2 A∙g−1的电流密度下,初始放电比容量达到1303.7 mAh∙g−1,且在100次循环后仍具有882.8 mAh∙g−1的可逆容量,比容量保留率达到64%。

The high specific capacity, the highest volume capacity, and the rich content of the earth, have made silicon-based materials attract more attention. However, low conductivity of silicon itself, the large volume effect during charging and discharging, and the instability of the SEI film result in poor cycle performance and restrict the high-performance application of silicon-based anode materials. In this paper, ZIF-67, Polymethyl Methacrylate (PMMA), Polyacrylonitrile (PAN), and Si were used to prepare multi-level nanofibers through three-layer coaxial electrospinning technology to solve the defects of silicon-based anode materials. Due to the addition of ZIF-67 and PMMA, the graphitization degree of the composite material is increased (the value of ID/IG decreases to 0.96), and the conductivity is improved. At the same time, the ion diffusion rate and charge transfer efficiency are improved. The initial discharge specific capacity reaches 1303.7 mAh∙g−1 at the current density of 0.2 A∙g−1. There is still a reversible capacity of 882.8 mAh∙g−1 after 100 cycles, and the specific capacity retention rate is 64%.