3D ordered Mesoporous Si/C Sphere Arrays as High-Volumetric-Capacity and Durable Anode for Lithium-ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Micro-nanostructured Si/C composites are promising anode materials for high-performance lithium-ion batteries (LIBs).
• Existing Si/C anodes often suffer from suboptimal volumetric capacities due to silicon's volume expansion during cycling.
• Efficient electrolyte and ion diffusion pathways are crucial for battery performance.

Purpose of the Study:

• To introduce a novel 3D ordered mesoporous Si/N-doped carbon (Si/NC) sphere array (M-Si/NC-SA) as an anode material for LIBs.
• To enhance volumetric capacity and cycling stability of silicon-based anodes.
• To provide efficient pathways for electrolyte and Li+ diffusion while accommodating silicon's volume expansion.

Main Methods:

• Fabrication of 3D ordered mesoporous Si/NC sphere arrays (M-Si/NC-SA).
• Characterization of the material's structure, including mesopores and macropores.
• Electrochemical testing of the M-Si/NC-SA anode in LIBs, including capacity, rate performance, and cycling stability.

Main Results:

• The optimal M-Si/NC-SA anode achieved a high compacted density of 0.78 mg cm⁻³.
• An impressive volumetric capacity of 2275 mAh cm⁻³ at 0.1 A g⁻¹ and 1011 mAh g⁻¹ at 1 A g⁻¹ after 1000 cycles were delivered.
• Full cells demonstrated practically relevant attributes when paired with lithium iron phosphate cathodes.

Conclusions:

• The M-Si/NC-SA structure effectively accommodates silicon volume expansion, preventing pulverization and enhancing cycling stability.
• This novel anode design significantly boosts volumetric capacity, addressing a critical limitation of Si/C anodes.
• A kilogram-scale production method was established, paving the way for practical application in next-generation LIBs.