Silicon-Integrated Acid-Etched SnO₂/N-CNT Composite as a High-Capacity Anode for Lithium-Ion Batteries

Herein, we report the rational design of an A-SnO₂/Si@N-CNT nanocomposite, fabricated via facile ball milling followed by high-temperature annealing. In this design, surface-modified SnO₂ (A-SnO₂) serves as the primary active framework, silicon nanoparticles are introduced to enhance overall capacity, and nitrogen-doped carbon nanotubes (N-CNTs) provide a conductive and mechanically resilient network. The incorporation of silicon nanoparticles and N-CNTs into A-SnO₂ facilitated the formation of strong Si-C and Si-O-Sn bonds, thereby improving electrical conductivity and structural stability and reinforcing interfacial interactions between the active materials and the conductive CNT matrix, resulting in superior electrochemical performance. Morphological analysis confirmed that the composite maintained structural stability without severe cracking after 100 cycles at 100 mAh g^-1. The electrode delivered reversible capacities of 1002 and 622 mAh g^-1 at 0.1 and 0.5 A g^-1, with capacity retentions of 78.7% and 73.17%, respectively. Even at 1.0 A g^-1, a stable capacity of 441 mAh g^-1 with 80.96% retention was achieved. These findings demonstrate the effectiveness of coupling surface-modified SnO₂ with Si- and N-doped carbon frameworks for advanced lithium-ion battery anodes.