Mg2SiO4/Si-Coated Disproportionated SiO Composite Anodes with High Initial Coulombic Efficiency for Lithium Ion Batteries

Silicon monoxide (SiO) is considered as one of the most promising anode material candidates for next-generation high-energy-density lithium ion batteries (LIBs) due to its high specific capacity and relatively lower volume expansion than that of Si. However, a large number of irreversible products are formed during the first charging and discharging process, resulting in a low initial Coulombic efficiency (ICE) of SiO. Herein, we report an economical and convenient method to increase the ICE of SiO without sacrificing its specific capacity by a solid reaction between magnesium silicide (Mg2Si) and micron-sized SiO. The reaction product (named MSO) exhibits a unique core-shell structure with uniformly distributed Mg2SiO4 and Si as the shell and disproportionated SiO as the core. MSO exhibits a superior ICE and a high reversible capacity of 81.7% and 1306.1 mAh g(-1), respectively, which can be further increased to 88.7% and 1446.4 mAh g(-1) after carbon coating, and improved cyclic stability compared to bare SiO. This work provides a simple yet effective strategy to address the low ICE issue of SiO anode materials to promote the practical application of SiO.

Automated summary

This study reports an economical and convenient method to increase the initial Coulombic efficiency (ICE) of silicon monoxide (SiO) anode material and successfully synthesizes a reaction product (MSO) with a core-shell structure. The MSO exhibits superior ICE, reversible capacity, and improved cyclic stability.