Constructing Densely Compacted Graphite/Si/SiO₂ Ternary Composite Anodes for High-Performance Li-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Graphite is the dominant anode material for lithium-ion batteries (LIBs) but is nearing its theoretical capacity limits.
• Enhancing anode capacity often involves blending silicon (Si) with graphite, but this can reduce areal capacity due to void spaces and poor particle distribution.
• Developing advanced anode materials is crucial for next-generation LIBs in electric vehicles and consumer electronics.

Purpose of the Study:

• To design and investigate compact ternary composite anodes of graphite/Si/SiO2 for enhanced areal capacity in LIBs.
• To address the issue of reduced areal capacity in graphite-Si composite anodes caused by void spaces and incompatible particle sizes.
• To establish a packing model for densely compacted anodes and verify its effectiveness through experimental validation.

Main Methods:

• Fabrication of graphite/Si/SiO2 ternary composite anodes with homogeneously dispersed Si/SiO2 clusters in graphite interstitial spaces.
• Electrochemical performance testing, including capacity, cycle life, coulombic efficiency, and areal capacity measurements.
• Development and experimental verification of a packing model to guide the design of densely compacted anodes.

Main Results:

• The graphite/Si/SiO2 composite electrodes achieved a high gravimetric capacity of 553.6 mAh g-1 after 700 cycles with 95.2% capacity retention.
• Demonstrated high coulombic efficiency (average 99.68% from 2nd to 200th cycles) and sustained areal capacities over 1.75 mAh cm-2 at a high loading of 4.04 mg cm-2.
• The Si/SiO2 clusters effectively filled void spaces, significantly increasing packing density and areal capacity compared to pure graphite.

Conclusions:

• The rational design of compact graphite/Si/SiO2 ternary composites offers a viable strategy to overcome the limitations of traditional graphite anodes.
• Optimized dispersion of Si/SiO2 clusters within graphite interstitial spaces enhances packing density, leading to superior areal capacity and long-term stability.
• This approach provides an effective solution for developing high-performance graphite-Si composite anodes for advanced lithium-ion cells.