Mechanically Adaptive Dense Multiscale Silicon-Carbon Architectures for Stable High-Capacity Lithium-Ion Batteries

Achieving high-energy-density lithium-ion batteries (LIBs) requires silicon (Si) anodes that can operate reliably under the high compaction densities demanded by practical cells. However, severe volume fluctuations and unstable interfacial chemistry continue to induce mechanical failure and rapid performance decay. Here, we introduce a hierarchically engineered composite anode (NSi₅₀/PSi@C) that integrates a porous silicon scaffold, infiltrated nano-silicon (NSi), and a conformal carbon coating. This architecture creates a continuous electron-conducting network, homogenizes stress distribution through nanoscale Si buffering, and preserves ion diffusion channels by preventing pore collapse. Coupled with a mechanically compliant carbon shell that stabilizes the solid electrolyte interphase (SEI) and maintains interfacial integrity, the electrode exhibits significantly improved charge-transfer kinetics and structural robustness. Benefiting from this multi-level design, NSi₅₀/PSi@C achieves a high compaction density of 1.38 g cm^-3 while delivering 1316.6 mAh g^-1 after 300 cycles with only 38% thickness expansion. The anode maintains >600 mAh g^-1 at 5 A g^-1 and demonstrates stable operation at elevated areal loadings. These results validate an effective design principle that simultaneously addresses mechanical, interfacial, and kinetic limitations, offering a scalable pathway toward practical, high-density silicon anodes for next-generation LIBs.