Tuning Diffusion Preferences in Silicon-Based Anodes for Enhanced Rapid and Homogeneous Lithiation

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Silicon (Si) anodes suffer from sluggish lithiation kinetics and significant volume expansion, leading to performance degradation.
• Existing Si-based anodes face challenges with lithiation retardation and structural instability.
• Commercial photovoltaic silicon waste (Si_pv) presents a potential but underutilized anode material.

Purpose of the Study:

• To propose and validate a Li⁺-diffusion-preference tuning strategy for homogeneous lithiation of silicon.
• To enhance the electrochemical performance and structural stability of silicon anodes.
• To utilize recycled photovoltaic silicon waste as an anode material.

Main Methods:

• Developed a strategy to guide Li⁺ diffusion preferentially along grain boundaries (GBs) in Si particles.
• Validated the strategy through computational simulations and experimental testing.
• Fabricated and tested Si_pv/graphite (Si_pv/g) composite anodes.

Main Results:

• Achieved rapid and homogeneous lithiation throughout Si particles by preferential Li⁺ diffusion along GBs.
• Demonstrated enhanced structural stability of Si_pv due to isotropic lithiation and grain strengthening effects.
• Si_pv/g anodes exhibited 93.8% capacity retention after 1000 cycles and a 136.2% capacity increase at -20 °C compared to commercial Si anodes.

Conclusions:

• The Li⁺-diffusion-preference tuning strategy effectively overcomes lithiation retardation in silicon anodes.
• Utilizing Si_pv with enhanced structural integrity leads to superior electrochemical performance and stability.
• This approach offers a viable method for improving silicon-based anodes for next-generation batteries.