The cyclic stability of Si anodes is still a great challenge for high-performance lithium-ion batteries due to the huge volume change. In this work, the continuous volume expansion of the Si anode and individual nanoparticles during cycling is deeply investigated by various visualization observations, and it is effectively suppressed by an artificial solid electrolyte interphase (SEI) consisting of inner polydopamine and outer natural SEI. Visualization characterization unveils the mechanism of action of the artificial SEI in Si nanoparticles. Specifically, repeated plastic deformation causes the transformation from amorphous Si into clusters accompanied by interstitial space, which induces continuous volume expansion, and the high-modulus artificial SEI accommodates plastic deformation of Si clusters during cycling, holding the structural integrity of Si nanoparticles. The anode of Si nanoparticles anchored on expanded graphite with such artificial SEI achieves its theoretical specific capacity and maintains a discharge capacity close to 80% of the maximum (983 mAh g^–1), with little fading after 500 cycles. This work not only expands upon the understanding of plastic deformation and SEI but also provides some valuable information for the rational design of Si-based active materials.

中文翻译：

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用于高性能锂离子电池的人工固体电解质中间相抑制 Si 纳米颗粒的连续体积膨胀

由于巨大的体积变化，Si负极的循环稳定性对于高性能锂离子电池来说仍然是一个巨大的挑战。在这项工作中，通过各种可视化观察深入研究了循环过程中 Si 负极和单个纳米颗粒的连续体积膨胀，并且它被由内部聚多巴胺和外部天然 SEI 组成的人工固体电解质中间相 (SEI) 有效抑制。可视化表征揭示了人工 SEI 在 Si 纳米粒子中的作用机制。具体而言，反复塑性变形导致非晶态 Si 转变为伴随间隙空间的团簇，从而引起连续的体积膨胀，并且高模量人工 SEI 适应循环过程中 Si 团簇的塑性变形，保持Si纳米颗粒的结构完整性。用这种人造 SEI 锚定在膨胀石墨上的 Si 纳米颗粒的阳极达到了其理论比容量，并保持了接近最大值 (983 mAh g) 的 80% 的放电容量。^–1 )，500 次循环后几乎没有褪色。这项工作不仅扩展了对塑性变形和 SEI 的理解，而且为硅基活性材料的合理设计提供了一些有价值的信息。