Silicon-based all-solid-state batteries operating free from external pressure

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Silicon-based all-solid-state batteries (ASSBs) promise high energy density and safety.
• A major challenge for ASSBs is the requirement for high external pressure to ensure proper electrode contact and ionic conductivity.
• This pressure requirement hinders practical application and scalability.

Purpose of the Study:

• To develop a novel anode for ASSBs that operates without external pressure.
• To enhance lithium-ion flux and stability at the anode interface.
• To improve the cycling performance and safety of silicon-based ASSBs.

Main Methods:

• Fabrication of a Li21Si5/Si-Li21Si5 double-layered anode using cold-pressed sintering of Li21Si5 alloys.
• Characterization of the anode's layered structure, ionic/electronic conduction, and conductive network.
• Electrochemical testing of the anode in ASSBs, including galvanostatic cycling and performance evaluation under various conditions.

Main Results:

• The double-layered anode exhibits a top Li21Si5 layer with mixed ionic/electronic conduction and a bottom Si-Li21Si5 layer with a 3D continuous conductive network.
• The anode enables operation free from external pressure by creating a uniform electric field at the anode|solid-state electrolyte interface.
• Achieved a critical current density of 10 mA cm⁻² at 45°C with 10 mAh cm⁻² capacity, and a cell demonstrated 97% initial Coulombic efficiency and low expansion after 1000 cycles.

Conclusions:

• The developed Li21Si5/Si-Li21Si5 anode effectively addresses the external pressure challenge in silicon-based ASSBs.
• The unique anode structure facilitates efficient ionic and electronic transport, leading to improved lithium-ion flux and stress dissipation.
• This advancement contributes to the development of safer, high-performance ASSBs for future energy storage applications.