Iron‐Driven Internal Percolation Enables Topological Construction of 3D Interconnected Porous Si@C Anodes

ABSTRACT Constructing internal voids is an effective strategy to mitigate the severe lithiation‐induced volume expansion of Si anodes for lithium‐ion batteries. Nevertheless, porous Si prepared via conventional reduction methods commonly undergoes structural shrinkage and uncontrollable pore configuration. Herein, a novel iron‐driven internal percolation mechanism is proposed to fabricate porous Si@C composites (p‐Si@C) through the ion exchange between Fe‐based Prussian blue templates and silicate anions, followed by low‐temperature molten‐salt aluminothermic reduction. The in‐situ formed Fe network acts as an electronic highway to accelerate the reduction of SiO 2 , while functioning as a sacrificial template to maintain a non‐shrinking topological framework with interconnected pores. Moreover, iron species catalyze the growth of graphitized carbon shells, inducing the formation of a LiF‐rich solid electrolyte interphase. Benefiting from the optimized structure, the p‐Si@C anode delivers a high reversible capacity of 605 mAh g −1 at 8 A g −1 , and the full cell paired with LiFePO 4 retains 95% of its capacity after 550 cycles. This work develops an innovative fabrication strategy for controllable porous Si based on the metal‐driven internal percolation mechanism, which can be extended to the rational design of other porous electrode materials.