Fluorinated MXene-engineered LiF-rich solid electrolyte interphase and hierarchical confinement strategy enabling high performance micro-sized silicon anodes

Abstract

Silicon (Si) anodes, despite their exceptional theoretical capacity (~4200 mAh g^-1), face critical challenges including severe volumetric expansion (>300%) during lithiation and poor intrinsic conductivity, resulting in structural pulverization and unstable solid-electrolyte interphase (SEI) formation. This work demonstrates a hierarchical confinement strategy integrating self-assembly and chemical vapor deposition (CVD) to construct microporous silicon-based composite anodes (mpSi-MGC) synergistically encapsulated by few-layer Ti₃C₂T_x MXene, reduced graphene oxide (rGO), and CVD carbon coating. The multi-confinement architecture not only enhances mechanical stability but also optimizes electron (e^-)/ lithium ions (Li⁺) transport kinetics. Systematic ex situ analysis reveals that fluorine-functionalized groups in Ti₃C₂T_x significantly boost Li⁺ diffusion coefficients by promoting LiF-rich SEI formation, while the exterior CVD-carbon coating further stabilizes the hybrid structure. The optimized mpSi-MGC delivers exceptional Li storage performance: a high reversible initial capacity of 1800 mAh g^-1 at 0.2 A g^-1, remarkable cyclability with 992 mAh g^-1 retained after 200 cycles at 1.0 A g^-1, and superior rate capability (818 mAh g^-1 at 3 A g^-1). This multi-scale confinement design effectively mitigates volume expansion in micron-sized Si while enhancing e^-/Li⁺ conductivity, offering a promising paradigm for developing high-energy-density lithium-ion batteries (LIBs) through rational structural engineering and interfacial optimization.

Topics & Concepts