Covalently Anchored MXene-Infiltrated Porous Silicon for Mechanically Resilient Lithium-Ion Battery Anodes

Silicon is among the most promising anodes for high-energy lithium-ion batteries due to its ultrahigh theoretical capacity; however, its catastrophic volume fluctuations and interfacial instability remain the primary obstacles to practical application. Here, we report a covalently integrated MXene-infiltrated porous silicon (MPSi) architecture that simultaneously delivers mechanical resilience, electronic continuity, and interfacial stability. Distinct from conventional surface-coating designs, few-layer Ti3C2Tx MXene nanosheets are driven deep into micron-scale porous silicon via ethanol-assisted wetting and vacuum-impregnation, forming a three-dimensional conductive network throughout the entire particle interior. Subsequent mild annealing induces dehydration condensation between Si-OH and Ti-OH groups, creating robust Si-O-Ti bonds that chemically anchor MXene to the silicon framework. This confinement-induced interfacial chemistry effectively suppresses MXene delamination, regulates solid electrolyte interphase evolution, and ensures long-range charge transport even under repeated volumetric expansion. Benefiting from the synergistic contributions of hierarchical internal voids, embedded MXene pathways, and covalent interfacial adhesion, the MPSi anode achieves high reversible capacity (906.3 mAh g-1 after 300 cycles at 1 A g-1), excellent rate capability (543.3 mAh g-1 at 5 A g-1), and improved initial Coulombic efficiency. Furthermore, the practical viability of this architecture is validated in full cells paired with NCM811 cathodes, which exhibit stable cycling with 80.2% capacity retention after 200 cycles. Detailed kinetic analysis further reveals dominant pseudocapacitive behavior enabled by the MXene-reinforced porous network. This work establishes an infiltration-driven, covalently bonded MXene-Si architecture that addresses both mechanical and electrochemical degradation of silicon anodes, offering a scalable strategy toward next-generation high-energy lithium-ion batteries.