Tailored Synthesis of Conformal Si–Al Coatings on TiO2 Nanotubes for Hybrid Negative Electrodes of Lithium-Ion Batteries

An original synthesis route has been developed to optimize silicon's utility in replacing graphite as anode material in Li-ion batteries. This involves blending silicon with aluminum to enhance its conductivity. The silicon–aluminum is codeposited on a nanoporous titanium dioxide nanotube matrix, which serves as an active current collector, thereby eliminating the need for inactive binders and ensuring robust mechanical stability during cycling. The nanostructured negative electrode is fabricated through two electrochemical synthesis steps: first, the anodization of a titanium foil, followed by the coelectrodeposition of silicon and aluminum using a room temperature ionic liquid electrolyte. This coelectrodeposition enables the in situ integration of aluminum into the silicon deposit. The resulting Si–Al/TiO₂ nanotube nanocomposite anode exhibits improved cyclic stability and enhanced rate capability. The observed enhancement in battery electrochemical performance underscores the significance of this electrochemical process in fabricating such nanostructured silicon negative composite electrodes.