Formation Processes of a Solid Electrolyte Interphase at a Silicon/Sulfide Electrolyte Interface in a Model...

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Silicon anodes offer high capacity for next-generation batteries but suffer from poor cycle stability.
• Understanding interfacial reactions is key to improving silicon anode performance in all-solid-state batteries (ASSBs).

Purpose of the Study:

• To investigate the electrochemical reactions at the silicon/solid sulfide electrolyte interface in ASSBs.
• To characterize the formation and properties of the solid electrolyte interphase (SEI) on silicon anodes.

Main Methods:

• Fabrication of a model Si/sulfide electrolyte interface using cathodic arc plasma deposition.
• Analysis using hard X-ray photoelectron spectroscopy and neutron reflectometry.

Main Results:

• A dense silicon film with <1 nm roughness was prepared.
• Initial Li (de)alloying was limited, but stable cycling occurred subsequently.
• An interfacial layer composed of Li₂S, SiS₂, and P₂S₅ glasses formed during the first cycle.
• This layer acted as a Li-conductive, electron-insulating SEI, enabling reversible cycling.

Conclusions:

• The study elucidates the electrochemical processes at the Si/Li₃PS₄ interface.
• The formed SEI layer is critical for activating and stabilizing silicon anodes in ASSBs.
• Insights into SEI structure and properties can guide the development of high-performance ASSBs.