Layered sodium titanate nanostructures as a new electrode for high energy density supercapacitors

A flower-shaped hydrated layered sodium titanate material, Na2Ti2O4(OH)(2), have been synthesized through a facile hydrothermal method and subsequently converted into sodium free titania (anatase). Potential application of the Na2Ti2O4(OH)(2) as an electrode for supercapacitors under pseudo-capacitance storage mode is evaluated. The Na2Ti2O4(OH)(2) showed sixfold higher specific capacitance (C-S similar to 300 Fg(-1)) in an aqueous electrolyte than the anatase and demonstrated stable electrochemical cycling. This high C-S is originated from a combination of electrochemical double layer and pseudo-capacitance storage mechanisms. The presence of hydrated layered within some loose interlayer plays an important role in assisting the diffusion process of ions as confirmed in electrical impedance spectroscopy analysis. (C) 2013 Elsevier Ltd. All rights reserved.