Facile fabrication of SiO2 nanotubes coated with nitrogen-doped carbon layers as high-performance anodes for lithium-ion batteries

Silica-based anodes have attracted considerable attention because of their low discharge potential and high theoretical specific capacity. Herein, SiO2 nanotubes (SNTs) were prepared via the sol-gel method with an ammonium DL-tartrate template, followed by the coating of N-doped carbon layers on their surface through a simple dopamine self-polymerization. The unique hollow tubular structure can accommodate large volume expansions. Notably, N-doped carbon layers play a crucial role in enhancing the SiO2 conductivity and increasing the Li+ diffusion rate. Furthermore, SNTs with high specific surface areas provide numerous sites for electron and Li+ insertion during lithiation. Hence, under the combined effect of the above-mentioned properties, N-doped carbon-coated SNTs (SNTs@NC) composites exhibited excellent cycling and rate performances. At a current density of 100 mA g(-1), SNTs@NC composites delivered a reversible specific capacity of 781 mA h g(-1) after the 200th cycle. Even at 1 A g(-1), the composites achieved a value of 522 mA h g(-1). With such excellent electrochemical properties, SNTs@NC composite material can serve as the next-generation anode for lithium-ion batteries.