Extending Si/C Anode Longevity through the Electrode Structure and Composition Design for All-Solid-State Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Silicon anodes face challenges in all-solid-state batteries (ASSBs) due to volume changes and lithium trapping, leading to capacity fade.
• Carbon-silicon composites improve electronic transport but do not fully resolve lithium trapping issues.

Purpose of the Study:

• To mitigate lithium trapping and enhance the performance of silicon-based anodes in ASSBs.
• To investigate the effects of incorporating a Li$_{3.75}$Si alloy into Si/C composites using bilayer and blended electrode architectures.

Main Methods:

• Fabrication of bilayer and blended electrodes incorporating a Li$_{3.75}$Si alloy into a Si/C composite.
• Electrochemical cycling and performance evaluation of the fabricated electrodes in ASSBs.
• Measurement of electrode critical current density (CCD) using a custom three-electrode cell setup.
• Addition of solid electrolyte (SE) to blended electrodes to assess its impact on ionic and electronic conductivity.

Main Results:

• The bilayer electrode showed better cycling performance but was prone to soft shorting at high current densities.
• The blended electrode exhibited a three-fold increase in CCD but had limited cycling stability.
• Adding solid electrolyte to the blended electrode significantly improved cycling performance, achieving 500 cycles at 0.8 mA/cm$^2$ and 183 cycles at 3 mA/cm$^2$ when paired with Ni-rich cathodes.

Conclusions:

• Regulating electrode structure and composition by incorporating Li$_{3.75}$Si alloy and solid electrolyte is effective in enhancing the performance of silicon-based anodes.
• The developed electrode strategies offer insights for creating long-lasting, high-rate, and dendrite-free Si-based ASSBs.