High pseudocapacitance boosts the performance of monolithic porous carbon cloth/closely packed TiO2 nanodots as an anode of an all-flexible sodium-ion battery

Abstract

Fabrication of a flexible electrode with high mass loading, excellent sodium storage properties and long cycling life is important to enable the commercial use of sodium-ion batteries in portable electronic devices. In this study, a monolithic porous carbon cloth/closely packed TiO₂ nanodot electrode was prepared as an anode for sodium-ion batteries by a one-pot hydrothermal method followed by calcination in air. The sufficient electrolyte transfer channel, resulting in an enhanced Na⁺ ion diffusion coefficient, and high pseudocapacitance of the TiO₂ nanodots prompt rapid sodium ion storage and confine the volume variation during cycling. Moreover, due to high sodium storage capacity of the porous carbon cloth and the excellent combination of the porous carbon cloth and the TiO₂ nanodots, the optimized electrode with a mass loading of 5.0 mg cm⁻² exhibits a high energy density (2.20 mA h cm⁻² at 0.2 mA cm⁻²) and long cycling stability (72.8% capacity retention after 2000 cycles). In addition, an all-flexible sodium-ion battery based on the optimized electrode as an anode and CC-Na₃V₂(PO₄)₃ as a cathode was fabricated, and it showed outstanding flexibility with negligible capacity fading at different bending states. This study offers new insight into the design of flexible electrodes with high mass loading and excellent electrochemical performance.