Modulus-Engineered Silicates-Buffering Matrix for Enhanced Lithium Storage of Micro-Sized SiO Anodes.

Microscale Silicon suboxide (SiO) is a promising anode material and elemental doping is an effective strategy to enhance the initial coulombic efficiency (ICE) and cycle stability of SiO by converting SiO into the electrochemically inert silicates-buffering matrix. However, the impact of the silicates-buffering modulus on the electrochemical properties is not well understood. Herein, the modulus of the silicate-buffering matrix is found to be crucial to restraining internal cracks and improving the electrochemical properties of microscale SiO during cycling. Compared with the LiSiO and MgSiO buffering matrixes, MgSiO has a higher modulus and yield stress resulting in better resistance to Si expansion-induced cracks during cycling. Moreover, MgSiO has a smaller Li diffusion energy barrier than LiSiO and MgSiO. Consequently, the microscale Mg-doped SiO with the MgSiO buffering matrix has a high ICE, excellent structural integrity, and small electrode expansion during cycling. The results provide insights into the design of microscale SiO anode materials by optimizing the silicates-buffering matrix for high-energy Li-ion batteries.