Ultrathin Na2Ti2O4(OH)2 nanowall for boosting sodium storage

Abstract

A hydrated layered sodium titanate nanowall has been realized through a facile hydrothermal process. Such Na2Ti2O4(OH)2 (NTOH) nanowall consists of ultrathin nanosheets vertically aligned on the Ti foil, delivers a reversible capacity of 191 mAh g−1 at 50 mA g−1 after 200 cycles. At a high charge/discharge rate of 2000 mA g−1, 92 mAh g−1 can be obtained after 1000 cycles. The structure features offer multiple superiorities for optimizing sodium storage. The presence of loose ultrathin nanosheets with open framework plays an important role on assisting the contact of ions in electrolyte. Additionally, the vertically oriented nanosheets can provide direct and independent paths for electron movement to fasten reaction kinetics, leading to excellent rate performance. Our method provides a new insight to design advanced titanate-based layered materials anodes for energy storage devices.