Gradient-Interlocked Solid Electrolyte Interphase via Spatial Reconfiguration for Stable Silicon Anodes in...

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Silicon anodes offer high energy density for solid-state batteries (SSBs).
• Volume expansion of silicon anodes causes solid electrolyte interphase (SEI) fracture and interface instability.
• Rigid interfaces in SSBs lack mechanical buffering for volume changes.

Purpose of the Study:

• To develop a stable SEI structure for silicon anodes in SSBs.
• To address the challenge of SEI fracture and electrode instability during cycling.
• To enhance the performance and cycle life of silicon-based SSBs.

Main Methods:

• Introduced cyclotetrasiloxane into polymer electrolytes to create a "mortise-tenon" SEI structure.
• Achieved interlock between cyclotetrasiloxane and LiF-rich inorganic phase for SEI stability.
• Fabricated and tested Si||Li half cells and NCM811||Si and LFP||Si full cells.

Main Results:

• The "mortise-tenon" SEI demonstrated robust adhesion and structural stability under large volume changes.
• Si||Li half cells achieved a high capacity of 1553.6 mAh g^-1 at 12 A g^-1.
• Full cells exhibited excellent capacity retention (97.6% over 300 cycles for NCM811||Si) and low decay rates (0.07‰ per cycle for LFP||Si over 700 cycles).

Conclusions:

• The developed SEI engineering strategy effectively stabilizes silicon anodes in SSBs.
• This approach enables the practical application of high-energy-density silicon-based SSBs.
• The "mortise-tenon" SEI provides a pathway for durable and high-performance energy storage solutions.