Unveiling the Effect of Surface and Bulk Structure on Electrochemical Properties of Disproportionated SiOx Anodes

Abstract

AbstractAs a promising lithium‐ion battery anode materials, silicon suboxides (SiOx) exhibit elusive microstructure with atomic‐scale disproportionation which reveals a strong relation to performance. Generally, the structure of SiOx could be tuned via high‐temperature treatment. In this work, disproportionated SiOx are prepared to systematically discuss the internal relationship among microstructure, physicochemical properties and electrochemical performance. After annealing, amorphous SiO2 and nanocrystalline Si appear, and the SiO2 accumulating on the surface results in large resistance and low Li‐ion diffusivity, which leads to large overpotential and poor performance. If mechanical milling is employed followed by annealing, the SiO2 layer can be crushed, SiOx and Si with electrochemical activity are uncovered. Further research on the SiOx with diverse degrees of disproportionation indicates that proper amount of Si and SiO2 determines the optimal electrochemical performance. This result gives an in‐depth understanding and probable guidance to the modification investigation of SiOx anode for Li‐ion batteries.