Battery and Electrochemistry Laboratory, Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
ACS Appl Mater Interfaces. 2013 Aug 14;5(15):7299-307. doi: 10.1021/am401642c. Epub 2013 Aug 1.
Silicon is widely regarded as one of the most promising anode materials for lithium ion and next-generation lithium batteries because of its high theoretical specific capacity. However, major issues arise from the large volume changes during alloying with lithium. In recent years, much effort has been spent on preparing nanostructured silicon and optimizing various aspects of material processing with the goal of preserving the electrode integrity upon lithiation/delithiation. The performance of silicon anodes is known to depend on a large number of parameters and, thus, the general definition of a "standard" is virtually impossible. In this work, we conduct a comparative performance study of silicon anode tapes prepared from commercially available materials while using both a well-defined electrode configuration and cycling method. Our results demonstrate that the polymer binder has a profound effect on the cell performance. Furthermore, we show that key parameters such as specific capacity, capacity retention, rate capability, and so forth can be strongly affected by the choice of silicon material, polymer binder and electrolyte system - even the formation of metastable crystalline Li15Si4 is found to depend on the electrode composition and low potential exposure time. Overall, the use of either poly(acrylic acid) with a viscosity-average molecular weight of 450.000 or poly(vinyl alcohol) Selvol 425 in combination with both silicon nanopowder containing a native oxide surface layer of ∼1 nm in diameter and with a monofluoroethylene carbonate-based electrolyte led to improved cycling stability at high loadings.
硅被广泛认为是最有前途的锂离子和下一代锂电池的阳极材料之一，因为其具有高的理论比容量。然而，在与锂合金化过程中会出现体积膨胀的大问题。近年来，人们致力于制备纳米结构硅，并优化材料处理的各个方面，以在锂化/脱锂过程中保持电极的完整性。硅阳极的性能取决于许多参数，因此，实际上不可能定义一个“标准”。在这项工作中，我们使用了明确的电极配置和循环方法，对来自市售材料的硅阳极带进行了比较性能研究。我们的结果表明，聚合物粘结剂对电池性能有深远的影响。此外，我们还表明，比容量、容量保持率、倍率性能等关键参数可能会受到硅材料、聚合物粘结剂和电解质体系的选择的强烈影响——甚至发现亚稳晶 Li15Si4 的形成也取决于电极组成和低电位暴露时间。总的来说，使用分子量为 450.000 的聚（丙烯酸）或 Selvol 425 的聚乙烯醇与直径约为 1nm 的具有天然氧化层的硅纳米粉末以及基于一氟代碳酸乙烯酯的电解质结合使用，可提高高负荷下的循环稳定性。
