Si/C composites represent one promising class of anode materials for next‐generation lithium‐ion batteries. To achieve high performances of Si‐based anodes, it is critical to control the surface oxide of Si particles, so as to harness the chemomechanical confinement effect of surface oxide on the large volume changes of Si particles during lithiation/delithiation. Here a systematic study of Si@SiO_x/C nanocomposite electrodes consisting of Si nanoparticles covered by a thin layer of surface oxide with a tunable thickness in the range of 1–10 nm is reported. It is shown that the oxidation temperature and time not only control the thickness of the surface oxide, but also change the structure and valence state of Si in the surface oxide. These factors can have a strong influence on the lithiation/delithiation behavior of Si nanoparticles, leading to different electrochemical performances. By combining experimental and modeling studies, an optimal thickness of about 5 nm for the surface oxide layer of Si nanoparticles is identified, which enables a combination of high capacity and long cycle stability of the Si@SiO_x/C nanocomposite anodes. This work provides an in‐depth understanding of the effects of surface oxide on the Si/C nanocomposite electrodes. Insights gained are important for the design of high‐performance Si/C composite electrodes.

中文翻译：

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控制高性能锂离子电池的Si / C纳米复合阳极中的表面氧化物

Si / C复合材料代表了下一代锂离子电池的一类很有前景的负极材料。为了获得高性能的硅基阳极，控制硅颗粒的表面氧化物至关重要，以便在锂化/脱锂过程中利用表面氧化物对硅颗粒的大体积变化的化学机械限制作用。这里对Si @ SiO _x进行了系统的研究报道了由硅纳米颗粒组成的/ C纳米复合电极，该纳米颗粒被表面氧化物薄层覆盖，其厚度可调范围为1-10 nm。结果表明，氧化温度和时间不仅控制着表面氧化物的厚度，而且改变了表面氧化物中Si的结构和价态。这些因素可能会对Si纳米粒子的锂化/脱锂行为产生重大影响，从而导致不同的电化学性能。通过实验和模型研究相结合，确定了Si纳米颗粒表面氧化物层的最佳厚度约为5 nm，从而实现了Si @ SiO _x的高容量和长循环稳定性的组合/ C纳米复合阳极。这项工作提供了对表面氧化物对Si / C纳米复合电极的影响的深入理解。获得的见解对于高性能Si / C复合电极的设计非常重要。