A Novel Structured Si-Based Composite with 2D Structured Graphite for High-Performance Lithium-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Silicon anodes offer high theoretical capacity for lithium-ion batteries (LIBs).
• Key challenges for silicon anodes include significant volume expansion and poor electronic conductivity.
• Composite materials are explored to mitigate silicon's intrinsic drawbacks.

Purpose of the Study:

• To synthesize and characterize a micro-sized spherical graphite@silicon@carbon (Gr@Si@C) anode composite.
• To evaluate the electrochemical performance of the Gr@Si@C composite as an anode for LIBs.
• To demonstrate the potential of Gr@Si@C in high-energy-density LIB applications.

Main Methods:

• Mechanofusion process for synthesizing the Gr@Si@C spherical composite.
• Characterization of the composite's unique core-shell structure formed by capillary forces.
• Electrochemical testing including capacity, cycling stability, and energy density measurements.

Main Results:

• The Gr@Si@C composite demonstrated a high capacity of 1622 mAh g^-1 and 72.2% capacity retention after 100 cycles.
• A high areal capacity of 4.2 mAh cm^-2 was achieved.
• Blended electrodes with commercial graphite showed excellent capacity retention and Coulombic efficiency.

Conclusions:

• The Gr@Si@C composite structure effectively overcomes silicon's inherent limitations.
• The Gr@Si@C anode enables high energy density (820 Wh L^-1) in LIBs with practical Si content.
• This composite material shows significant promise for commercializing high-performance LIBs.