Enhanced capacitance performance of Al2O3–TiO2 composite thin film via sol–gel using double chelators

[Display omitted] •A facile route is developed to synthesize TiO2 nanocrystal at room temperature.•Lactic acid and acetylacetone are used as double chelators.•Possible formation mechanism for TiO2 nanocrystal is proposed.•TiO2 hydrosol using double chelators possesses better wettability.•Obtained TiO2 enhanced capacitance performance of Al2O3–TiO2 composite thin film. Titanium dioxide (TiO2) is usually introduced into dielectric layer of aluminum electrolytic capacitor to enhance capacitance performance via forming Al2O3–TiO2 composite film. However, there is a big obstacle caused by high crystallization temperature of TiO2 to capacitance enhancement. In present work, a facile route was proposed to synthesize crystalline TiO2 with the size of 3–10nm at room temperature using lactic acid (LA) and acetylacetone (Acac) as double chelators. After being introduced into the surface of etched aluminum foils as dielectric layer, TiO2 boosted the specific capacitance by about 24% compared to that without TiO2, and about 11% compared to that with TiO2 using lactic acid as only chelator.