Overcoming the Limitation of Low Electrical Conductivity of LiF‐Rich SEI Toward Fast‐Charging and High‐Stability Silicon Anodes

Studies on the solid electrolyte interphase (SEI) formed via selective electrocatalysis often pay too much attention to LiF content while neglecting that the continuous accumulation of LiF severely limits fast‐charging capability due to its inherently low electrical conductivity. Herein, we propose a tailored core‐shell composite (Si@Fe 3 C‐NC) comprising Si nanoparticle cores encapsulated by a partially graphitized nitrogen (N)‐doped carbon shell embedded with uniform Fe 3 C nanoparticles. The synergistic effect of N‐doping and Fe‐induced partial graphitization of the carbon layer constructs efficient electron/ion transport pathways. Additionally, self‐encapsulated Fe 3 C nanoparticles not only selectively catalyze the formation of a thin and LiF‐rich SEI but also mitigate the conductivity loss caused by LiF accumulation. Consequently, the Si@Fe 3 C‐NC anode exhibits outstanding electrochemical performance, delivering an ICE of 90.2%, a high specific capacity of 1750.8 mAh g −1 after 300 cycles at 1 A g −1 , and excellent fast‐charging durability (858.8/539.2 mAh g −1 after 500/2000 cycles at 5 A g −1 ). Moreover, the 1 Ah pouch cells assembled with the Si@Fe 3 C‐NC anode and LFP/NCM811 commercial cathodes exhibit excellent fast‐charging performance and cycling stability over 200 cycles at 2 C. This study reveals the “dual role” of a LiF‐rich SEI and presents a promising strategy for its formation on Si anodes.