Surface halogenation engineering for reversible silicon-based solid-state batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Silicon-based solid-state batteries offer high energy density but face challenges with interfacial compatibility and kinetics.
• Poor electrochemical compatibility between silicon anodes and solid electrolytes like Li6PS5Cl limits battery reversibility and efficiency.

Purpose of the Study:

• To develop a surface modification strategy for silicon negative electrodes to enhance interfacial compatibility and electrochemical performance.
• To address sluggish interfacial kinetics and irreversible lithium loss in silicon-based solid-state batteries.

Main Methods:

• A surface halogenation strategy was employed, reacting the native SiO2 layer on silicon particles with AlCl3.
• This created a functional Al(Si)OCl composite interphase, improving ionic and electronic transport.

Main Results:

• The modified silicon electrode achieved high initial Coulombic efficiency (94.3% in half-cells, 85.6% in full cells).
• Long-term cycling showed 86% capacity retention over 200 cycles with 99.998% average Coulombic efficiency.
• High-loading electrodes retained 72% capacity after 500 cycles, and full cells maintained 80% capacity after 200 cycles at 1C.

Conclusions:

• The surface halogenation strategy effectively reconciles interfacial incompatibility in silicon-based solid-state batteries.
• This approach enables fast transport, suppresses irreversible lithium loss, and significantly enhances reversibility and cyclability.
• Halide chemistry presents a versatile pathway for advancing high-performance, reversible silicon-based solid-state batteries.