A Dual-Layer Carbon Encapsulation Strategy for Stable Silicon Anodes: Inner Volume Expansion Buffer and Outer...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Silicon anodes offer high theoretical capacity for advanced lithium-ion batteries (LIBs).
• Significant volume expansion during cycling leads to particle pulverization and unstable solid electrolyte interphase (SEI) formation.
• These issues hinder the practical application of silicon anodes in LIBs.

Purpose of the Study:

• To develop a silicon-carbon composite anode (Si@NPC@NC) with a dual-layer carbon architecture.
• To address the volume expansion and SEI instability challenges of silicon anodes.
• To enhance the electrochemical performance and cycle stability of LIBs.

Main Methods:

• Fabrication of a Si@NPC@NC composite anode with differentiated inner porous and outer dense carbon layers.
• Utilizing ZIF-67 and polydopamine (PDA) for constructing the dual-layer carbon architecture.
• Electrochemical testing including cycling performance, coulombic efficiency, and capacity retention measurements.

Main Results:

• The Si@NPC@NC anode exhibited an initial coulombic efficiency of 82%.
• Achieved a specific capacity of 1183 mAh g^-1 after 200 cycles at 0.2 A g^-1 with 88.2% capacity retention.
• Demonstrated superior performance compared to unmodified silicon and single-layer carbon-coated anodes.

Conclusions:

• The dual-layer carbon architecture effectively accommodates volume changes and stabilizes the electrode/electrolyte interface.
• The Si@NPC@NC anode presents a viable strategy for developing high-performance and stable silicon anodes for LIBs.
• This design approach offers insights for improving other high-volume-change anode materials.