Direct fabrication of SnO2- and MoO3-modified nanoporous TiO2–TiO–TiN composite films by hybrid anodization for high-safety lithium-ion battery anodes

Abstract

Although modification with SnO2 or MoO3 is known to improve the properties of TiO2-based anode materials for lithium-ion batteries (LIBs), simple fabrication methods are required to realize practical applications. Herein, we report a novel approach to fabricate SnO2- or MoO3-modified nanoporous TiO2–TiO–TiN composite films by a hybrid anodization process in nitric-based aqueous solutions containing SnO32− or Mo7O246− ions. Concurrent anodic reactions resulted in Ti anodization to produce a composite film and the electrophoretic deposition of SnO2 or MoO3 colloids in the nanopores of the matrix film. Both TiO2–TiO–TiN@SnO2 and TiO2–TiO–TiN@MoO3 composite films exhibited enhanced discharge capacities (~5- and 3-fold higher than that of the bare matrix film). This enhanced performance was attributed to the synergic effect of improved charge-transfer and additional capacity by depositing nanocrystalline SnO2 and MoO3 nanoparticles in the TiO2–TiO–TiN films, and the presence of nanoporous structures, which provided suitable Li+ transfer paths and reaction sites. The hybridization of nanoporous TiO2 films with SnO2 and MoO3 nanoparticles can simultaneously enhance the discharge capacity and address structural degradation issues in Sn- and MoO3-based electrodes. This simple hybrid anodization approach provides a promising strategy for designing high-power-density and high-safety anode materials for future LIBs.