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

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Microscale silicon suboxide (SiOₓ) is a promising anode material for lithium-ion batteries.
• Elemental doping enhances SiOₓ performance by creating a silicate-buffering matrix.
• The influence of the silicate-buffering matrix's modulus on electrochemical properties remains unclear.

Purpose of the Study:

• To investigate the crucial role of the silicate-buffering matrix modulus in microscale SiOₓ anodes.
• To understand how matrix modulus affects structural integrity and electrochemical performance during cycling.
• To identify an optimal silicate-buffering matrix for enhanced battery performance.

Main Methods:

• Doping microscale SiOₓ with elements to form different silicate-buffering matrices (Li₂SiO₃, MgSiO₃, Mg₂SiO₄).
• Characterizing the mechanical properties (modulus, yield stress) of the silicate matrices.
• Evaluating electrochemical properties including initial coulombic efficiency (ICE), cycle stability, and electrode expansion.

Main Results:

• Mg₂SiO₄ exhibits a higher modulus and yield stress compared to Li₂SiO₃ and MgSiO₃, effectively restraining internal cracks.
• The Mg₂SiO₄ matrix shows a lower Li⁺ diffusion energy barrier.
• Microscale Mg-doped SiOₓ with a Mg₂SiO₄ matrix demonstrates high ICE, excellent structural integrity, and minimal electrode expansion.

Conclusions:

• The modulus of the silicate-buffering matrix is critical for improving the electrochemical properties and structural stability of microscale SiOₓ anodes.
• Mg₂SiO₄ is identified as a superior buffering matrix due to its mechanical strength and favorable Li⁺ diffusion kinetics.
• Optimizing the silicate-buffering matrix offers a pathway for designing advanced anode materials for high-energy lithium-ion batteries.