Enhancement Mechanism of Photo-Induced Artificial Boundary on Ultrastable Hybrid Solid-electrolyte Interphase of Si Anodes

Abstract

Unstable solid-electrolyte interphase (SEI) film resulting from chemically active surface state and huge volume fluctuation limits the development of Si-based anode materials in lithium-ion batteries. Herein, a photo-initiated polypyrrole (PPy) coating is manufactured on Si nanoparticles to guide the in situ generation of PPy-integrated hybrid SEI film (hSEI). The hSEI film shows excellent structure stability and optimized component composition for lithium storage. More promisingly, the photo-initiated hSEI precursor with more uniform thickness, stronger interaction with inner particles, and higher mechanical strength further enables the structural integrity of the hSEI film. The highly ordered interchain structure of photo-initiated hSEI precursor can maintain effective Li⁺ transport during the electrochemical cycling. Consequently, SiNPs@hSEI-L anode maintains a reversible capacity of 1044.7 mAh g⁻¹ after 500 cycles at 2 A g⁻¹, manifesting superior electrochemical lithium storage. This work proposes a novel polymer-integrated hSEI formation and provides an effective reference for the optimization of semiconductor materials.