Functionally Gradient Silicon/Graphite Composite Electrodes Enabling Stable Cycling and High Capacity for Lithium-Ion...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Silicon (Si) is a promising anode material for high-energy-density lithium-ion batteries (LIBs).
• The primary challenge for Si anodes is the significant volume change during lithium insertion/extraction, causing electrode degradation and capacity fade.

Purpose of the Study:

• To develop a scalable method for fabricating functionally gradient Si/graphite (Si/Gr) composite electrodes.
• To mitigate structural degradation caused by volume changes and enhance the capacity of Si-based anodes.

Main Methods:

• A facile and scalable multilayer coating approach was employed to create Si/Gr composite electrodes with a parabolic gradient (PG) distribution of Si.
• Experimental characterizations and chemomechanical simulations were used to analyze electrode structure and performance.
• Electrochemical testing of Si/Gr anodes and Si/Gr||NCM532 full cells under various conditions.

Main Results:

• The PG-Si/Gr electrode demonstrated improved structural stability and high capacity due to the optimized spatial distribution of Si and graphite particles.
• High mass loading electrodes (3.15 mg cm^-2 and 8.45 mg cm^-2) exhibited excellent reversible capacities (579.2 mAh g^-1 and 4.04 mAh cm^-2, respectively) with sustained cycling stability.
• The full cell achieved an initial reversible areal capacity of 1.64 mAh cm^-2, maintaining 0.94 mAh cm^-2 after 100 cycles.

Conclusions:

• The proposed parabolic gradient distribution effectively addresses the volume expansion issue in Si anodes.
• The developed Si/Gr composite electrodes offer a viable solution for high-energy-density and stable lithium-ion batteries.
• This scalable fabrication method paves the way for practical applications of advanced Si-based anodes.