Silicon-Based Composite Anodes for All-Solid-State Lithium-Ion Batteries Conceived by a Mixture Design Approach

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Silicon anodes offer high theoretical capacity for lithium-ion batteries but suffer from volume expansion and poor cycling stability.
• Developing stable solid-state electrolytes is critical for enhancing battery safety and energy density.

Purpose of the Study:

• To investigate the composition-performance relationship of silicon-based anodes incorporating a LiI-Li3 PS4 solid electrolyte (LPSI).
• To optimize anode formulations for improved capacity and cycling stability in bulk-type all-solid-state batteries.

Main Methods:

• Utilized a mixture design approach to systematically vary the proportions of silicon (Si), graphite (MAG), and LPSI in the anode composite.
• Incorporated carbon nanofiber (CNF) as a conductive additive.
• Fabricated and tested bulk-type all-solid-state batteries with LPSI as the solid electrolyte.
• Employed Scanning Electron Microscopy (SEM) to analyze anode microstructure.

Main Results:

• Increasing the fraction of LPSI in the anode composite improved electrode capacity.
• The optimal Si/MAG/LPSI ratio of 15:15:70, with 5 wt% CNF, achieved a capacity exceeding 1200 mAh/g over 50 cycles.
• SEM analysis revealed that LPSI addition effectively suppressed Si aggregation and enhanced Si utilization during electrochemical cycling.

Conclusions:

• A straightforward manual grinding method can produce high-performance silicon-based anodes.
• The optimized anode composition demonstrates significant potential for high-capacity and stable cycling in all-solid-state batteries.
• LPSI plays a crucial role in stabilizing silicon anodes by preventing aggregation and improving lithium-ion transport.