Modulus‐Engineered Silicates‐Buffering Matrix for Enhanced Lithium Storage of Micro‐Sized SiOx Anodes

Abstract Microscale Silicon suboxide (SiO x ) is a promising anode material and elemental doping is an effective strategy to enhance the initial coulombic efficiency (ICE) and cycle stability of SiO x by converting SiO 2 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 x during cycling. Compared with the Li 2 SiO 3 and MgSiO 3 buffering matrixes, Mg 2 SiO 4 has a higher modulus and yield stress resulting in better resistance to Si expansion‐induced cracks during cycling. Moreover, Mg 2 SiO 4 has a smaller Li + diffusion energy barrier than Li 2 SiO 3 and MgSiO 3 . Consequently, the microscale Mg‐doped SiO x with the Mg 2 SiO 4 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 x anode materials by optimizing the silicates‐buffering matrix for high‐energy Li‐ion batteries.