Shi Wenyue, Wu Hao Bin, Baucom Jesse, Li Xianyang, Ma Shengxiang, Chen Gen, Lu Yunfeng
Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States.
School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, Zhejiang, China.
ACS Appl Mater Interfaces. 2020 Sep 2;12(35):39127-39134. doi: 10.1021/acsami.0c09938. Epub 2020 Aug 19.
Silicon is one of the most promising anode materials for lithium-ion batteries due to its high theoretical capacity and low cost. However, significant capacity fading caused by severe structural degradation during cycling limits its practical implication. To overcome this barrier, we design a covalently bonded nanocomposite of silicon and poly(vinyl alcohol) (Si-PVA) by high-energy ball-milling of a mixture of micron-sized Si and PVA. The obtained Si nanoparticles are wrapped by resilient PVA coatings that covalently bond to the Si particles. In such nanostructures, the soft PVA coatings can accommodate the volume change of the Si particles during repeated lithiation and delithiation. Simultaneously, as formed covalent bonds enhance the mechanical strength of the coatings. Due to the significantly improved structural stability, the Si-PVA composite delivers a lifespan of 100 cycles with a high capacity of 1526 mAh g. In addition, a high initial Coulombic efficiency of over 86% and an average value of 99.2% in subsequent cycles can be achieved. This reactive ball-milling strategy provides a low-cost and scalable route to fabricate high-performance anode materials.
硅因其高理论容量和低成本，是锂离子电池最具前景的负极材料之一。然而，循环过程中严重的结构退化导致显著的容量衰减，限制了其实际应用。为克服这一障碍，我们通过对微米级硅和聚乙烯醇（PVA）的混合物进行高能球磨，设计了一种硅与聚乙烯醇的共价键合纳米复合材料（Si-PVA）。所制备的硅纳米颗粒被弹性的PVA涂层包裹，该涂层与硅颗粒共价键合。在这种纳米结构中，柔软的PVA涂层能够在反复锂化和脱锂过程中适应硅颗粒的体积变化。同时，形成的共价键增强了涂层的机械强度。由于结构稳定性显著提高，Si-PVA复合材料具有100次循环的寿命，高容量为1526 mAh g。此外，初始库仑效率超过86%，后续循环的平均值为99.2%。这种反应性球磨策略为制备高性能负极材料提供了一种低成本且可扩展的途径。
