The direct growth of SnO2 on vertically aligned carbon nanotube arrays as high-performance anode for lithium ion batteries.

SnO2-based anodes offer a higher theoretical capacity than conventional graphite, positioning them as a promising alternative for lithium-ion batteries. Nevertheless, poor conductivity and substantial volume changes during cycling restrict their widespread implementation. We hypothesize that combining vertically aligned carbon nanotube arrays (VACNTs), which serve as a conductive scaffold, with a citric-acid-derived carbon coating creates a dual‑carbon architecture that improves the cycling stability and charge transport of SnO2, thereby enhancing lithium storage performance. To verify this hypothesis, we employ a single-step interfacial functionalization strategy. This approach involves the in situ growth of SnO2 from a SnCl4·5H2O precursor on VACNTs, followed by in situ carbon coating using citric acid as the carbon source, ultimately constructing a dual‑carbon-structured SnO2/VACNTs@C composite. Within this structure, SnO2 nanoparticles are uniformly embedded in the VACNTs scaffold. This confined geometry effectively accommodates volume changes during lithiation/ delithiation, and the strong SnO2/VACNTs interfacial bonding enhances mechanical integrity and electrical conductivity. As a result, the SnO2/VACNTs@C anode demonstrates superior reversible capacity and rate performance compared to both pure SnO2 and uncoated SnO2/VACNTs electrodes. Compared with pristine SnO2, the material achieves a substantial improvement in lithium-ion diffusion coefficient. Paired with a LiFePO4 cathode in a full-cell configuration, it further delivers robust cycling stability, notable capacity retention, and competitive energy and power densities. This synthesis route offers a scalable method for the mass production of this high-performance composite.