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

As a promising lithium-ion battery anode materials, silicon suboxides (SiO x ) exhibit elusive microstructure with atomic-scale disproportionation which reveals a strong relation to performance. Generally, the structure of SiO x could be tuned via high-temperature treatment. In this work, disproportionated SiO x are prepared to systematically discuss the internal relationship among microstructure, physicochemical properties and electrochemical performance. After annealing, amorphous SiO 2 and nanocrystalline Si appear, and the SiO 2 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 SiO 2 layer can be crushed, SiO x and Si with electrochemical activity are uncovered. Further research on the SiO x with diverse degrees of disproportionation indicates that proper amount of Si and SiO 2 determines the optimal electrochemical performance. This result gives an in-depth understanding and probable guidance to the modification investigation of SiO x anode for Li-ion batteries.