Rambutan-inspired tri-layer architecture with regulated strain and lithium transport for high-capacity and stable...

The stable cycling of high-capacity electrode materials with substantial volume variations presents a persistent challenge, primarily attributed to structural instability and inefficient charge transport. Herein, inspired by the rambutan fruit's hierarchical structure, we propose a tri-layer composite architecture that synergistically optimizes strain relaxation and Li⁺ transport. The inner layer, typically vulnerable to severe strain and prolonged Li⁺ diffusion pathways, is composed of a Sn/Cr₂O₃/C nanocomposite with rapid (de)lithiation kinetics and moderate volume expansion. The intermediate layer, strategically designed for intrinsic strain accommodation and minimized lithium diffusion distance, features Si nanoparticles homogeneously dispersed within a conductive carbon matrix. The outmost layer comprises core-sheath-structured Sn@carbon nanotubes, establishing dual conductive pathways for both lithium ions and electrons. This design elegantly reconciles the high capacity of Si with large volume effect through strain relaxation. The resulting composite achieves an optimized equilibrium among strain accommodation, ion transport, and interfacial stability, ultimately leading to high capacity (1089 mAh g^-1 at 0.1 A g^-1) and stable cycling (580 mAh g^-1 after 700 cycles at 0.5 A g^-1).