Rigid‐Flexible Synergistic Buffer Layer Design in Mn/Co Bimetallic MOF‐Derived Core–Shell Silicon‐Based Anodes for Enhanced Lithium Storage Performance

Silicon-based anode materials emerge as pivotal candidates for next-generation high-energy-density lithium-ion batteries owing to their ultrahigh theoretical capacity (4200 mAh g- 1). Nevertheless, their practical application faces substantial challenges from rapid capacity fading caused by severe volume expansion (>300%). Herein, an in situ solvothermal strategy is proposed to grow Mn/Co bimetallic MOF (MC-BTC) precursors on silicon nanoparticles, which is then transformed into carbon/MnO/CoO composite buffer layers through controlled pyrolysis. The results reveal the formation of spherical shell architectures encapsulating silicon cores, establishing a rigid support framework between core and shell domains. This hierarchical configuration effectively mitigates the particle expansion while preserving electrode integrity through synergistic rigid-flexible interactions. The optimized Si@MC-BTC-C composite demonstrates remarkable electrochemical performance, delivering 1270 mAh g- 1 at 2 C and maintaining 806 mAh g- 1 after 1000 cycles at 10 C with an ultralow decay rate of 0.06% per cycle, representing a significant enhancement of cycling stability compared to the original silicon systems. This work presents an innovative interfacial engineering design to alleviate the severe volume expansion in silicon anodes, providing a potential pathway for their scale-up deployment in advanced energy storage systems.