Lithium-ion cells are currently the most promising electrochemical power sources. New high-capacity electrodes made of silicon are presently under intensive study. Besides its high capacity, silicon undergoes a significant volume increase (up to 300%) during lithiation. The main research on the silicon-based electrodes is focused on the nanostructure development and capacity/life cycle measurements. Variations in other electrochemical parameters, SEI layer resistance and charge transfer resistance, are also important and give the information about structural changes and mechanisms of side processes that occur during an electrode lithiation/delithiation. This work presents electrochemical impedance spectroscopy measurements of three silicon–graphite composite electrodes, containing various silicon contents. A clear correlation between the SEI and charge transfer resistances and the active material lithiation level is presented. The effect of the cycle number on the measured parameters is also visible. We present possible mechanisms that lead to observed changes and highlight the requirement of the proper Si-based electrode formation and the correct estimation of operational parameters.

中文翻译：

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锂离子电池硅基电极的电化学阻抗谱表征

锂离子电池目前是最有前途的电化学电源。目前正在对由硅制成的新型大容量电极进行深入研究。除了其高容量外，硅在锂化过程中还经历了体积的显着增加（高达300％）。对硅基电极的主要研究集中在纳米结构的发展和容量/寿命周期的测量上。其他电化学参数（SEI层电阻和电荷转移电阻）的变化也很重要，它们可提供有关在电极锂化/去锂化过程中发生的结构变化和副过程机理的信息。这项工作介绍了三个含硅含量不同的硅-石墨复合电极的电化学阻抗谱测量。提出了SEI和电荷转移电阻与活性材料锂化程度之间的明确关联。循环数对测量参数的影响也是可见的。我们提出了可能导致观察到的变化的机制，并强调了适当的硅基电极形成的要求以及对运行参数的正确估计。