Silicon monoxide (SiO) as a promising silicon-based anode electrode of lithium-ion batteries (LIBs) has been the subject of many recent investigations. However, the complex microstructural features of SiO hinder attempts to link the microstructure changes in SiO with its electrochemical performances upon electrochemical cycling. This study employs X-ray pair distribution function (PDF), with a high-resolution transmission electron microscope (HRTEM), to investigate the microstructure of Si nanodomains in SiO and its structural evolution over the electrochemical cycling process. The experiment results reveal the size evolution of Si nanodomains in SiO during the electrochemical cycling and find it highly dependent on the initial Si domain size in SiO. If the initial Si domain size is too large, the average size of Si nanodomains would increase at first and then decrease after a certain number of cycles, which indicates the pulverization of Si domains after the electrochemical-driven growth of Si nanodomains reaches a critical point. These results suggest that an optimal initial Si nanodomain size of 4–6 nm for SiO anode materials is essential to retard the growth and subsequent pulverization process of Si nanodomains and thus to improve the cyclability of SiO during long-term cycling.

一氧化硅（SiO）作为锂离子电池（LIB）的有希望的硅基阳极电极已成为许多近期研究的主题。然而，SiO的复杂的微结构特征阻碍了试图将SiO的微结构变化与其在电化学循环时的电化学性能联系起来。这项研究利用X射线对分布函数（PDF）和高分辨率透射电子显微镜（HRTEM），研究了SiO中Si纳米域的微观结构及其在电化学循环过程中的结构演变。实验结果揭示了在电化学循环过程中SiO中Si纳米域的尺寸演变，发现它高度依赖于SiO中的初始Si域尺寸。如果初始Si区域太大，Si纳米域的平均尺寸首先增加，然后经过一定数量的循环后减小，这表明在电化学驱动的Si纳米域生长达到临界点后，Si域被粉碎。这些结果表明，对于SiO阳极材料而言，最佳的初始Si纳米域尺寸为4–6 nm对于延缓Si纳米域的生长和随后的粉碎过程，从而改善SiO在长期循环过程中的可循环性至关重要。